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Outdoor Free Flight Forum => P-30 Class Sport and Competition => Topic started by: calgoddard on June 07, 2020, 02:52:11 PM



Title: Flat Wing P-30
Post by: calgoddard on June 07, 2020, 02:52:11 PM
I am a member of the San Diego Orbiteers free flight club.  That club was responsible for originating the P-30 event in the late 1970’s. I have seven (7) built P-30 models and two (2) un-built P-30 kits.  My P-30 models range from John Oldenkamp’s low-tech HOT BOX P-30 to Burdov’s high-tech Pirate P-30. Obviously, I like the P-30 class.

Tomorrow marks the beginning of my fourth month of stay-at-home. I have started to build a different P-30 wing just for fun.  I want it to incorporate a design that looks different, is relatively easy to build, resists warping, and hopefully provides good performance. My plan is to use it as a substitute for the existing wing of my Air Shark P-30.  The wing of that model has a large 5-inch chord and a difficult geodetic rib construction.  It has dihedral wing tip sections.  The ribs of my Air Shark wing have under camber.  I am attaching a picture of my Air Shark P-30 which is an excellent flier, particularly in the glide.  I fly it with a 10 x 1/16-inch rubber motor that weighs 9.8 grams prior to lubing.

The Air Shark P-30 was designed by Stan Buddenbohm and has been around since at least the early 1990’s. Most people know Stan as a world class designer and flier of HLG and CLG models.  However, he has flown rubber powered models for many years and is pretty much unbeatable in any class of rubber powered models that he flies.  However, I have not seen him fly F1B models.

I have never seen a P-30 wing that is flat with vertical tip plates.  DerekMc please confirm that you are not aware of a P-30 with such a wing configuration. As pretty much everyone in our hobby knows, tip plates provide effective dihedral that gives roll stability.  I have used them with great success in my indoor LLP and A-6 models where they greatly simplify wing construction. My plan is to use the NACA 6409 airfoil in my P-30 “flat wing” to hopefully get a floaty glide.  This airfoil has a slight under camber.  My outdoor flat wing will have a 5-inch chord and will use carbon fiber (CF) composite tube for the wing spar as is common practice in modern F1G models and some P-30 models like Berdov’s Pirate.  I plan to cover my P-30 flat wing with ¼-mil Mylar film or MicroLite film.  The ribs, leading edge, and trailing edge of the flat wing will be made of balsa wood. I am just planning to use my Air Shark fuselage, prop assembly and tail feathers as a convenient test bed for my P-30 flat wing.

I understand that the use of a carbon fiber spar will provide torsional stability and resist wing warping. Therefore, I can use simple parallel ribs made of 1/16-inch sheet balsa wood and avoid the complex geodetic rib wing construction of my Air Shark wing.  I plan to include false ribs, i.e. short “partial” ribs that extend in parallel fashion from the leading edge to the spar, between the full-size ribs.  During construction I will shim the rear wing tips to provide about 1/8-inch of wash-out to improve roll stability and impede any tendency for the model to spiral into the ground if upset by turbulence. The tip plates will be made of light 1/16-inch sheet balsa wood.

The current wing on my Air Shark P-30 weighs 16.97 grams.  The wing of my Pirate P-30 weighs only 11.52 grams, but it has a much narrower chord yielding a much higher aspect ratio than my current Air Shark wing.  I’d like my P-30 flat wing to weigh somewhere between these two sample weights. I want my modified Air Shark P-30 to have a weight near the 40-gram minimum allowed under the P-30 rules followed in the United States.
 
I am wondering if I should cap the tops of the full-size balsa wood ribs with CF material?  If so, what CF material?  With this capped construction the ribs could be made of 6# density balsa wood.  More specifically, what CF material should I purchase from www.cstsales.com? I assume it should be very lightweight unidirectional CF material.  Do I just cut it to length and width and glue it to the top edges of the full-size ribs with CA? How do I keep the un-woven fibers together when cutting and prior to gluing?

I don’t know how to build a D-box wing such as that used in Don DeLoach’s Polecat MK. X P-30. That’s a challenge for some future P-30 project.

There are some who post on HPA that feel very strongly that since P-30 is a beginner’s class, that construction of P-30s should be kept simple to stay true to the spirit of the rules.  But I sometimes compete against world class fliers like Stan Buddenbohm, Don DeLoach and Clint Brooks. You need a strong P-30 with a good design that is well-trimmed and near minimum weight in order to have any chance of getting into a fly-off with these fliers.  They are masters at picking good air.  In addition, I know that Stan winds to very high torque. Don and Clint probably do the same.  I am not yet to the point of including VIT into a P-30 as these world class fliers don’t do that.  However, Tapio Linkosalo has indicated that I may gain an advantage by keeping the stab at zero degrees incidence for the first four seconds after launch. Maybe someday I will experiment with VIT on a P-30 but I would need a good, lightweight timer that can activate both the VIT and the DT in a consistent and reliable manner.

I apologize in advance if I have offended any of the P-30 purists.  In their defense, I admit that flying a simple P-30 model, I did win the very first P-30 contest I entered.  In that contest I flew my rudimentary Square Eagle P-30 against very experienced P-30 competitors.  It seems to me that there is room for both types of P-30 enthusiasts in our hobby - those who like simple models and those who want to take advantage of high-tech materials and more advanced mechanisms.  A P-30 constructed with carbon fiber and plastic film is stronger and less prone to warping than a stick and tissue P-30.  I do like the appearance and nostalgia of the latter type of P-30 which can still be very competitive in the right hands.

Your thoughts and comments would be appreciated.


Title: Re: Flat Wing P-30
Post by: TimWescott on June 07, 2020, 03:18:12 PM
... As pretty much everyone in our hobby knows, tip plates provide effective dihedral that gives roll stability.  I have used them with great success in my indoor LLP and A-6 models where they greatly simplify wing construction.

Not me, and I've been flying for about 40 years.  But my rank in FF is "piker".  Are you sure this isn't just something that only applies to super-low Reynolds numbers, like indoor?

... My outdoor flat wing will have a 5-inch chord and will use carbon fiber (CF) composite tube for the wing spar as is common practice in modern F1G models and some P-30 models like Berdov’s Pirate. ... I plan to cover my P-30 flat wing with ¼-mil Mylar film or MicroLite film.

That sounds like a lot more added complication than anything you're subtracting by having a dead flat wing, particularly because you're signing up to those big tip plates.

I'll be interested in seeing how it all works out, particularly if your tip plates = dihedral notion works at P-30 Reynolds numbers.


Title: Re: Flat Wing P-30
Post by: RalphS on June 07, 2020, 03:58:46 PM
Geat class, like Coupes.  Simple and easy to experiment.  I would be worried that the large upright tip plates would easily break off in bad/windy landings but, on the other hand, easy to try.

Just one more thing - why P30?  I understand the 30, being the dimensions, but what is the meaning of the "P"? 


Title: Re: Flat Wing P-30
Post by: flydean1 on June 07, 2020, 04:13:50 PM
Ralph, the "P" stands for the plastic prop.

Someone on this Forum has built an end plate flat wing P30.  Hopefully he will chime in.

Darcy Whyte's beginner model called "Squirrel" has a flat wing with end plates.  I think his web site is called "Endless Lift" or something like that.


Title: Re: Flat Wing P-30
Post by: flydean1 on June 07, 2020, 04:38:13 PM
I knew I had it somewhere.  The builder was Ding Zuarte from somewhere on the West Coast.  We corresponded briefly via PM on the Forum.  At the time (2012) he was actively flying it in his club's monthly meets.  It flew OK, but could not recover from a death spiral which occurred after a major upset.  The wing was flat except for some washin on the left tip.


Title: Re: Flat Wing P-30
Post by: DerekMc on June 07, 2020, 05:16:08 PM
Calgoddard, I haven't seen a plan for a P30 wing like what you are describing. I look forward to flight reports! 


Title: Re: Flat Wing P-30
Post by: flydean1 on June 07, 2020, 06:34:18 PM
Went back to the correspondence.  Ding was flying with a club in the Sacramento area.  Searched the Endless Lift site.  No picture of the P30.


Title: Re: Flat Wing P-30
Post by: randoloid on June 07, 2020, 08:42:03 PM
I too will be following and hope to hear progress reports. 


I'm fairly new the the hobby and have only built three P-30's. The first two were Majestyk's by Thom Greenhalge. My first flew OOS due to a fuse malfunction on a test flight before my first planned competition. The second actually made it there... I dearly love that plane.

My second build is the above mentioned Don DeLoach Polecat X.  I chose it because I was attracted by the wing construction and the use of carbon caps. 

Quote
I am wondering if I should cap the tops of the full-size balsa wood ribs with CF material?  If so, what CF material?


The carbon is 1/16 strips 36"L. I purchased mine from Mike Woodhouse also the short kit of the Polecat as well as Mylar.  Don's wing construction is super rigid and the carbon caps add a lot of strength and rigidity with very little weight. While I could have built it lighter, I'm very pleased with the all up weight of around 51g.  I have just finished the build and only glided the model but hope to log powered flights very soon.



Title: Re: Flat Wing P-30
Post by: lincoln on June 07, 2020, 11:38:38 PM
I think pre cured, unidirectional carbon fiber laminates would be the right thing for reinforcing the ribs. I suspect that the .005" thickness that CST sells is overkill. This stuff is easily stripped with a knife, but watch out for splinters any time you are handling it.

A carbon tube is far from the lightest way to add torsional stiffness to a wing. Fiber orientation is important. If all the fibers run parallel to the axis, it won't be very stiff. The lightest way may be carbon capped diagonal ribs. However, there may be some kind of covering that will also do a good job, assuming it doesn't shrink so hard it bends the leading and trailing edges or crush the ribs.


Title: Re: Flat Wing P-30
Post by: Tapio Linkosalo on June 08, 2020, 12:31:42 AM

I do my carbon capped ribs (for larger FAI model tailplanes and E-36) by carving a rib block from balsa, laminating uni-directional carbon over it and then cutting the individual ribs out of the block with a miniature tabletop circular saw and a diamond cutting disk. Not for P-30 though, for that I use conventional ribs and only a short length of carbon capping at the trailing edge, to strengthen that thin and weak part, and to solidly glue the carbon strip trailing edge to the wing (too little surface area to glue to balsa rib only).

For spars, the russian thin-walled non-tapering carbon tubes (if I understand correctly made by Burdov, I buy then from Mike Woodouse in the UK) make superior spars. 5.5mm diameter for the center sections and 3.5mm for the tips. No more weight than balsa spars, and super solid and stiff wings. Much recommended.



Title: Re: Flat Wing P-30
Post by: lincoln on June 08, 2020, 01:52:13 AM
BTW, the 6409 isn't so great for small, light models. If we can trust Profili, which uses Xfoil, you can do slightly better with a Neelmeyer airfoil, which is also about 9 percent thick, but flat bottomed, which would make it easier to build. This is based on a Reynods number of 30,000/sqrrtCl and a turbulator at 40 percent. If you want to get fancy, there are free flight airfoils which will perform somewhat better, with higher maximum lift and lower profile drag. They'll be a little harder to build, though. The Archer A-18 doesn't look too bad. However, with an open structure wing, you will only get the nominal Cl at the ribs, with an infinite number of other airfoils in between. A moderate Jedelsky airfoil doesn't have this problem, though I don't know if one could be made light enough unless you used foam, and in that case you could just hot wire a suitable section. At least Profili likes it. An advantage of the 6409 and the Jedelsky is that they develop a lot of drag at low lift coefficients. Maybe, particularly in P-30, they could be dethermalized with down elevator? I suppose with a lot of down elevator, the model would try to fly inverted, which might come down even faster, though it would probably flop around. Anyone ever experiment with this?


Title: Re: Flat Wing P-30
Post by: lincoln on June 08, 2020, 01:58:12 AM
Here's a rough picture of the Jedelsky airfoil I analyzed, plus a picture of the Neelmeyer, if I can find it.


Title: Re: Flat Wing P-30
Post by: TimWescott on June 08, 2020, 11:03:55 AM
... However, with an open structure wing, you will only get the nominal Cl at the ribs, with an infinite number of other airfoils in between. ...

There's a couple of Selig airfoils that are designed for this -- i.e., the published airfoil is a rib pattern, with sag expected between ribs.  The calculations and measurements are then done taking this into account. 

But I think they're for RC gliders; this would mean that the design Reynolds number would be at least 10 times greater.


Title: Re: Flat Wing P-30
Post by: cvasecuk on June 08, 2020, 11:40:09 AM
  But I sometimes compete against world class fliers like Stan Buddenbohm, Don DeLoach and Clint Brooks. ......  They are masters at picking good air. 
Surely that is the most important part of flying P30's!
Ron


Title: Re: Flat Wing P-30
Post by: lincoln on June 08, 2020, 02:42:05 PM
... However, with an open structure wing, you will only get the nominal airfoil at the ribs, with an infinite number of other airfoils in between. ...

There's a couple of Selig airfoils that are designed for this -- i.e., the published airfoil is a rib pattern, with sag expected between ribs.  The calculations and measurements are then done taking this into account. 

But I think they're for RC gliders; this would mean that the design Reynolds number would be at least 10 times greater.
I knew that there had been a couple of Drela airfoils that had flat segments behind the d-tube, but I hadn't heard of Selig airfoils that take sag into account. Do you remember,the names or a link? DJ Aerotech designs are supposed to account for sag, but they're proprietary and probably don't have enough camber for a P-30.

RC glider Reynolds numbers aren't all that much higher, except for slope soaring and dynamic,soaring. The latter can be so fast that the Mach number matters. The wing tip of a 1.5 meter glider in slow flight might have a Reynolds number of 60,000, but it would be much higher during a launch. I guess a big glider might have double that. Center sections will be somewhat higher.


Title: Re: Flat Wing P-30
Post by: TimWescott on June 09, 2020, 12:14:14 PM
... However, with an open structure wing, you will only get the nominal airfoil at the ribs, with an infinite number of other airfoils in between. ...

There's a couple of Selig airfoils that are designed for this -- i.e., the published airfoil is a rib pattern, with sag expected between ribs.  The calculations and measurements are then done taking this into account. 

But I think they're for RC gliders; this would mean that the design Reynolds number would be at least 10 times greater.
I knew that there had been a couple of Drela airfoils that had flat segments behind the d-tube, but I hadn't heard of Selig airfoils that take sag into account. Do you remember,the names or a link? DJ Aerotech designs are supposed to account for sag, but they're proprietary and probably don't have enough camber for a P-30.

RC glider Reynolds numbers aren't all that much higher, except for slope soaring and dynamic,soaring. The latter can be so fast that the Mach number matters. The wing tip of a 1.5 meter glider in slow flight might have a Reynolds number of 60,000, but it would be much higher during a launch. I guess a big glider might have double that. Center sections will be somewhat higher.


Gaa!  I just looked, and I think I was wrong -- Selig does mention sagging in a couple of articles, but only to the extent that "oh, it's not much".


Title: Re: Flat Wing P-30
Post by: calgoddard on June 10, 2020, 08:44:50 PM
Thanks everyone for your input.

In theory, tip plates on the wing should reduce wing tip vortices and drag. I am attaching a picture of a Science Olympiad Wright Stuff airplane with vertical tip plates (red in color) in case someone is not familiar with this type of wing configuration.

Tip plates of suitable size on the “flat wing” of a P-30 should effectively impart enough dihedral to yield sufficient lateral (roll) stability, during the climb, cruise and glide portions of its flight. Roll stability would be enhanced if 1/8-inch wash-out were incorporated into the wing tips.

The tip plates should extend from the LE to the TE of the wing, have a curved LE, and probably have a height of about ½ to ¾ of the wing chord.

It’s not likely that 1/16-inch sheet balsa wood tip plates on a P-30 wing would be damaged on landing, but they could be easily replaced if this happens.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 10, 2020, 08:46:13 PM
In recently reviewing the 2010 P-30 Summary published by Free Flight Quarterly (FFQ), I have so far not come across a “flat wing” P-30, i.e. one with a having tip plates instead of angled wing sections. Someone on this thread questioned whether tip plates will work with outdoor models since the wings have higher Reynolds numbers than those of indoor duration models like Limited Penny Planes. 

The Big Cat Embryo that is sold in kit form by Volare Products has vertical tip plates and is an excellent flier. See the attached picture of the Big Cat Embryo. This Embryo model probably flies in a speed range comparable to that of a P-30. I guess I will eventually find out through experimentation whether tip plates work on a P-30 wing. 


Title: Re: Flat Wing P-30
Post by: calgoddard on June 10, 2020, 08:47:50 PM
After scanning through the 2010 P-30 Summary published by FFQ, I have come to the realization that it is very unlikely that any P-30 design I might conceive and perfect would give me any advantage in a contest over the best of the proven designs like the Air Shark,  Polecat MK X, Pirate, and Boomer  MK III. Therefore, I have decided to shift my focus and try to develop a simple P-30 design for the beginner.  

A tissue-covered flat wing with no under camber in the ribs, and with sheet balsa wood tip plates instead of angled wing sections might be the simplest wing to construct for a P-30. It could be married with a balsa wood sheet-sided box fuselage, a flat stick and tissue stab, and a sheet balsa wood fin. Much of the fuselage could have large oval-shaped laser cut-outs to reduce weight and it could be covered with tissue to impart increased torsional stiffness (and color).  The edges of the sheet balsa wood sides could have laser cut interlocking tabs for ease of assembly and to ensure squareness and straightness of the completed box fuselage.  The holes for the motor peg could be located to provide a 19-inch hook-to-peg distance, which is the length of an unbraided conventional 6 x 1/8-inch 9.8-gram rubber motor made of Tan Super Sport rubber.

While I am a big fan of the Gizmo Geezer prop assembly, its installation, adjustment and clutch operation are probably a bit much for a novice.  I might include a simple thrust line adjustment mechanism similar to the single plastic screw design used by John McGrath in his Rocket Man P-20 kit. Perhaps laser cutting the front ends of the fuselage sides to provide 5 degrees of down thrust and 2 degrees of right thrust would be satisfactory, along with instructions to add shims for fine tuning.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 10, 2020, 08:48:54 PM
My beginner’s P-30 could include a flat wing frame measuring 29 ¾-inches x 4 1/8-inches to yield a wing area within the 120 - 124 square inch wing area sweet spot recommended by P-30 legend John Oldenkamp. These dimensions result in an aspect ratio of 7.2 to 1. The 1/16-inch sheet balsa wood vertical tip plates would be glued to the outer sides of the outermost wing ribs.

I would test stability of my beginner’s P-30 without any wash-out because building in wash-out, or warping it in after construction, may be too much of a challenge for many beginners.  If necessary, I could try adding simple balsa wood wedges or Gurney flaps to simulate wash-out. I would recommend trimming my beginner’s P-30 to fly in a right-right flight pattern due to the forces generated by the free-wheeling plastic prop during the glide. A wedge glued to the underside of the TE of the right inner portion of the wing to simulate wash-in might therefore be beneficial.

A DT would not be included in my beginner’s P-30 design as it would be too complex for beginners to install and rig.  At a projected 45-50 grams (without the rubber motor), a DT would not be necessary for recovering the model unless it encountered a boomer thermal. If the model were to fly away in a boomer thermal, and not be recovered, a replacement could be quickly assembled.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 10, 2020, 08:49:46 PM
If test flights validate the design of my beginner’s P-30, then I would offer the design free of charge to a friend who is in the business of making and selling laser-cut kits. Hopefully it would spur participation in the free flight hobby. I am thinking of calling my beginner’s model the THREE NITE P-30. This same suggests that a novice could construct my beginner’s P-30 in three evenings.

Thanks for reading my last five posts.  I am interested in your feedback.


Title: Re: Flat Wing P-30
Post by: flydean1 on June 10, 2020, 09:08:27 PM
I agree with everything except the lack of a DT.  Nothing would turn off today's kids like putting in all the effort and seeing it fly away.  It doesn't take a boomer to grab even a 55 - 60 gram P30.  A simple viscous damper is easy to set up and operate.  An instructional video on a DVD included would be helpful.


Title: Re: Flat Wing P-30
Post by: lincoln on June 10, 2020, 09:42:37 PM
Sounds like it would work. I haven't seen stick fuselage P-30's, with the rubber outside, with the exception of a design called Lazybones, which also has sheet balsa flying surfaces. Is there a reason such fuselages won't work? I've been thinking of building an Easy Built Ritz for P-30.


Title: Re: Flat Wing P-30
Post by: flydean1 on June 10, 2020, 10:18:29 PM
There's nothing in the rules outlawing an external rubber motor.  Probably torsional and possibly bending stiffness with a wound motor might be the issue.  It would greatly simplify the model. 

A "T" section fuselage would be simple to make, especially with interlocking tabs, and may address the torsion and bending stress.

The DT could be of the pop-up wing variety which would eliminate running a DT line back to the tail and routing it to avoid snags.

Another consideration on the flat wing concept:  Walt Mooney published a Ford Flivver peanut which was a low wing with zero dihedral.  He added a post forward of the cockpit which went vertically several inches and sported a large American Flag made of 1/16 sheet.  It flew very well according to Walt and several others outdoors as well as indoors.


Title: Re: Flat Wing P-30
Post by: lincoln on June 10, 2020, 10:39:31 PM
I have seen a paper bag and a P-30 wing get carried up from the ground by a dust devil. Once made 3 landing attempts witn an unpowered RC glider in a dust devil. Dust devils can be thought of as extreme thermals. If a DT were provided, some thought to make it as easy as possible to use.

Torsional stiffness might be enhanced by a spiral wrap of fiberglass or carbon tow. Just one or two tows, or maybe high tech fishing line. The latter wouldn't be stiff in compression, so at least one wrap in each direction would be required. An enclosd box would be much stiffer than a tee unless it was spiral wrapped with something.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 12, 2020, 08:19:22 PM
I have attached a picture of a prototype "flat wing" that I quickly built.  The soup can was included in the picture to give the viewer a better idea of the size of the wing. It measures 29 7/8-inches by 4 1/8-inches.  The tip plates have been tack glued on with generic glue similar to that sold under the Duco brand. They will later be easily removed with acetone before covering the wing with Esaki tissue.  When shrunk, that tissue will add a lot of torsional strength. I usually cover wings with the grain of the tissue extending span-wise.

The weight of the flat wing frame as shown is 10.40 grams.  That’s descent considering the heavy balsa wood I used to build it.
  
I purposefully used heavy balsa wood for durability and resistance to warps.  This wing will be a component of a beginner’s P-30 so there is no need to try to build near the 40-gram minimum set forth in the P-30 rules followed in the United States.  I used 9# wood for the 1/8-inch square leading edge (later rounded), and 12# wood for the 1/8-inch square main spar.  The two 1/16-inch square stringers were made of light balsa wood because that is all I had access to during my stay-at-home.  I am running low on 36-inch long sheets of 1/16-inch thick balsa wood. The ribs were cut from a sheet of 1/16-inch sheet balsa wood that had an overall density of 10#. Some of the individual ribs felt like they came from a lighter part of the sheet.

The tip plates measure 4 1/8-inches in length and have a maximum height of 2 5/8-inches.  They might be a bit tall. If test flights show that my beginner's P-30 exhibits good lateral stability, I may progressively cut down the tip plates with scissors at the flying field to see if they can be reduced in height without impairing roll stability and recovery from turbulence.  The tip plates weigh a combined 3.15 grams.  Reducing their height would reduce weight and drag.

The wing ribs have a Neelmeyer airfoil with a flat bottom.  Cutting, sanding and notching fourteen uniform ribs was time consuming.  A novice could easily assemble this wing frame in less than an hour with laser cut ribs. I purposefully did not build in any wash-out as I want to see if adequate lateral stability can be achieved without adding this complication for a novice.
 
For those who have been following this thread, you know my reason for using a flat wing on a beginner’s P-30 model.  To reiterate, novice builders often have difficulties properly inclining and joining built-up angled wing sections.  A flat wing with vertical tip plates is the easiest built-up wing to construct that can provide sufficient lateral (roll) stability.  The tip plates effectively provide the flat wing with dihedral.

As usual, your comments and suggestions are welcome.


Title: Re: Flat Wing P-30
Post by: applehoney on June 12, 2020, 08:41:02 PM
Cal, my only exposure to a 'flat wing' model was, decades ago, witnessing flights of a glider with this configuration - as published in a British magazine of the time.

It flew quite well in near calm conditions, was a little unhappy when towed quite fast in little wind; from what I remember of that far-off day  its stability was marginal and glide pattern easily upset.

With no more personal experience than this I would, with the greatest respect, not consider such a wing for a  P30 .. least of all for a beginner's design.  Had a flat wing have an advantage over dihedral/polyhedral then such would have long been seen in numbers on the flying field.  Other than general structural simplicity, stability is essential and I do not see a borderline level of such as fulfilling the requirement of intended  purpose.

Ultimate performance is not a requirement of a model proposed for youngsters, in particular. Easy to build, strong, easy to trim and fly proved ideal for my boys  (when they were boys!)  ... a robust model which briefly out-climbed  Coupes of the time ... no freewheel so a fast descent quickly returned the airplane to the flyer's hands. Novices do not seek ultimate performance ...  a stimulating power pattern,  a fair but fast glide ..and not far to walk to retrieve and return to wind up and fly again ... and again.

A strong ... if overweight ... dihedralled P30 with no freewheel would likely be good for up to a minute; given successful flights an upgrade to a freewheel would add some performance.  Hopefully the builder/flyer would be hooked by then  !

Cal, please appreciate  I'm not trying to wet-blanket your thoughts and proposition.  I hope you'll build and fly your flatwing airplane and would be  very interested in the outcome; I love  P30 and an improvement in layout and performance would always be welcome.

Respectfully,

Jim


Title: Re: Flat Wing P-30
Post by: calgoddard on June 12, 2020, 08:55:06 PM
Jim -

Thanks for your input. Yes, I too have wondered why there are few outdoor models with tip plates.

My latest free flight endeavor could well be a waste of time.  But I currently have time to waste.

I really liked the Square Eagle as a beginner's P-30 but it is no longer being kitted.  The ONE NITE 28 has been re-named by the successor to Peck-Polymers but is currently out of stock.  Unfortunately that model did not accept a typical P-30 blast tube.

The old HOT BOX design by John Oldenkamp is a very good beginner's P-30 if you have to scratch-build. It uses a "Cracked Rib" design in the wing which eliminates the tedious job of cutting, sanding and notching wing ribs.

Jim - I really want to thank you for all your input on HPA over the years.  Among other things, I think you stressed the need to round the upper surface of the nose block plug on OTR models.  This tip probably saved my carved balsa wood props from breaking on a number of occasions.



Title: Re: Flat Wing P-30
Post by: calgoddard on June 18, 2020, 06:17:39 PM
I am attaching a picture of the fuselage frame of my beginner’s P-30 which I just completed building.  It borrows from the design of the Square Eagle P-30 fuselage.  I constructed the fuselage in the picture with two “slab sides” made of 1/16-inch sheet balsa wood.  As shown, the fuselage frame weighs 8.4 grams.  

Fabricating and joining the slab sides from scratch took a lot longer than building a conventional box frame or making a rolled tube for the fuselage.  However, if the parts were laser cut the assembly would take less time to build than the traditional P-30 fuselage designs.
 
The fuselage measures 28-inches long x 1 1/8 -inch wide x 1-inch tall.  It will easily accept a blast tube of sufficient internal diameter to accommodate a standard 6 x 1/8-inch P-30 rubber motor. The laminated nose block and 9 ½-inch plastic prop (not shown in the picture) will extend about 1-inch forward from the front end of the fuselage.  If a Gizmo Geezer prop assembly is used, two inches of length beyond the forward end of the fuselage will ensure that  the airplane does not exceed the 30-inch limit in the P-30 rules.
 
I cut the ¾-inch round holes in the slab sides to save weight using a segment of Aluminum tube filed to sharpen one end.  This tool is similar to a hole punch except that you do not ram it through the balsa wood. Instead, you manually spin it to cut out a circle of balsa wood. Filing one end of a segment of a Brass tube or a Copper tube would probably make a better cutting tool as the edge would stay sharp for a longer period of use.  I didn’t have Brass tube or a Copper tube of this size available.

The motor peg holes are located to achieve a 19-inch hook-to-peg distance. That’s the length of a conventional 6 x 1/8-inch 9.8-gram P-30 rubber motor.  The area on the inside of each slab side surrounding its motor peg hole is reinforced with a small vertical section of 1/16-inch sheet balsa wood and a small square of 1/64-inch plywood. A 1/8-inch hole was drilled in each vertical balsa wood section and plywood square to accommodate a segment of 1/8-inch outside diameter Aluminum tube which will serve as the motor peg.

¼-inch diameter holes were drilled in the tail section of each slab slide to reduce weight. 3-inch long tapered notches, 1/8-inch tall at their forward ends, were cut into the upper edges of the tail section that will provide negative stab incidence of 2.4 degrees.
 
The slab sides were joined with 3/32-inch square balsa wood cross-pieces.  The fuselage sides with all the holes and notches can be laser-cut if my beginner’s P-30 is ever kitted.
 
The 3 ½-inch long nose section is fully sheeted without holes in the sheeting. This is because the modeler will need to handle this portion of the fuselage while inserting the nose block. In the nose region the upper edges of the slab sides and the rectangular top and bottom pieces can have laser cut interlocking notches to facilitate assembly.  A beginner should easily be able to assemble this fuselage frame in less than one hour using laser cut slab sides, laser cut top and bottom nose pieces, along with pre-cut 3/32-inch cross pieces.
 
I will cover the fuselage frame with Esaki tissue with the grain extending perpendicular to the longitudinal axis of the fuselage.  This will add considerable torsional strength once the tissue is shrunk and doped.

Your comments and suggestions are welcome. P-30 is a great event! I am hoping my beginner's P-30 will inspire beginners to become involved in the free flight hobby. Test flights will be needed to validate that the flat wing provides sufficient roll stability.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 22, 2020, 05:17:07 PM
I built a stab for my beginner’s P-30 as shown in the attached photograph. It mimics that of the Square Eagle P-30 except that I opted for twin 1/16-inch sheet balsa fins attached to the ends of the stab instead of a single vertical fin aligned with the center of the fuselage. Securely mounting a single vertical fin to the rear portion of the fuselage (common P-30 configuration) or the center of a horizontal stab in proper alignment can be difficult for a beginner.  In constructing the tail feathers of my beginner’s P-30, each fin can be readily glued in a vertical position to a corresponding outermost rib. In the attached photograph the twin fins have been tack glued onto the outermost ribs, and will later be removed to facilitate covering the stab with Esaki tissue.

The rear ends of the stab ribs are glued in notches in the trailing edge, to increase strength at these critical joints. These notches can be laser cut if my beginner’s P-30 is ever kitted. The span and chord of the stab (including its twin fins) measure 12 3/4-inches and 3 inches, respectively. The fins measure 3-inches in length x 1 ¾-inches in height x 1/16-inch thick.  Their combined area is more than double that of a typical single P-30 fin and therefore the twin fins should have enough area to provide sufficient yaw stability. The weight of the uncovered tail feathers as shown in the attached photograph is 3.31 grams.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 24, 2020, 12:46:23 PM
I made a mistake in constructing the stab of my beginner’s P-30.  It was supposed to have a 3/32-inch square main spar and two 1/16-inch square stop spars.  I simultaneously sanded notches in the lower side of a bunch of 1/16-inch sheet ribs for receiving the main spar using my 3/32-inch notch sander.  Then I incorrectly used the same sander to sand notches into the upper side of the bunch of ribs.  I forgot to switch to my 1/16-inch notch sander. When I realized my mistake, I decided it was too much work to make all new ribs.  Rough calculations using John Barker’s 2005 SHEET AND STRIP WEIGHTS IN GRAMS chart indicate that this error resulted in about 0.2 grams of additional weight.  This is still bad because even a small amount of unneeded weight at the end of a long tail moment is undesirable.  However, the upside of my mistake is that the stab will be less prone to warping with larger top spars.
 
If my beginner’s P-30 model is ever kitted, it will probably use a 1/16-inch x 1/8-inch main spar in the stab, with the 1/8-inch dimension oriented vertically.  It will use 1/16-inch square balsa wood sticks for the top spars and 1/16-inch sheet ribs. If the stab used 1/32-inch sheet ribs I fear it would be too delicate and too prone to warping with tissue covering.  Such a light construction would probably be fine with Mylar film covering.


Title: Re: Flat Wing P-30
Post by: flydean1 on June 24, 2020, 01:01:59 PM
Just an observation not necessarily negative:  Mylar covering requires a heat source to attach and shrink.  Many beginners won't have this.  Even domestic tissue, with all its' defects, will be easier to handle.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 26, 2020, 09:58:45 AM
flydean1 -

Thanks for your input. I agree that covering with Mylar film requires tools and skills that are very unlikely to be available to novices.

I intend my beginner's P-30 to be covered solely with tissue.

The comment at the end of my prior post should have said the following. Using 1/32-inch sheet ribs in the stab would require the use of Mylar film covering to avoid warps.  Therefore 1/16-inch sheet ribs will be used in the stab to permit tissue covering.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 26, 2020, 10:01:18 AM
A pre-assembly picture of my beginner’s P-30 is attached.  The weight as shown is 25.02 grams. I was not careful with balsa wood selection. The nose block and prop assembly will add at least 10 grams.  Adding the weight of the tissue and dope on the wing and stab, and the weight of the wing saddle will surely push the all-up-weight (less rubber) of the finished model above the 40-gram minimum set forth in the US rules for the P-30 event.  The finished model should come out less than 50 grams, and perhaps close to 45 grams. Nominal amounts of down thrust and right thrust have been sanded into the forward end of the fuselage.


Title: Re: Flat Wing P-30
Post by: BG on June 27, 2020, 03:06:22 AM
Looks nice. I agree with Jim's analysis though. I think she will fly but may be tricky in turbulence etc. In the end I think even rank beginners can handle a simple V dihedral wing with little trouble and the discussion regarding the particular need for more dihedral on FF models is an instructive one to have with any beginner in the hobby. The last thing we want to do is to give folks the impression that dihedral is optional.

just my two cents.

BG


Title: Re: Flat Wing P-30
Post by: calgoddard on June 27, 2020, 02:20:19 PM
Bernard -

I have great respect for your opinions based on your vast knowledge and experience in the free flight hobby.

You and Jim are probably correct that a flat wing P-30 is not be the best configuration for a beginner.

Right now I have the time to conduct this experiment.

At this time, I don't have access to a flying field and my winder, stooge, blast tubes, etc.

I will go ahead and finish this model in the hopes that I can do some test flights with it in the coming months.

Thanks for your input Bernard.  It is welcome.



Title: Re: Flat Wing P-30
Post by: calgoddard on July 19, 2020, 05:59:56 PM
The weight of my completed beginner’s P-30 model as shown is 45.5 grams (without rubber).  I was not careful with balsa wood selection during the build. Better wood selection would achieve a weight closer to the 40-gram minimum under the P-30 rules followed in the United States. By way of example, lighter 1/16-inch sheet balsa wood could be used for the tip plates on the ends of the wing and the twin fins on the ends of the stab. This would probably save a couple of grams.

I set the CG at a conservative 57.5%.  The CG is located 2 3/8-inches aft of the LE of the wing, which has a 4 1/8-inch chord. Right now, the down thrust is about 6-degrees due to the generous decalage. The right thrust is slightly over 2 degrees.
 
Low power tests flights in my small local park yesterday showed that this model exhibits sufficient roll stability in relatively calm conditions.  I wore a mask and stayed away from other people who were exercising their dogs.
 
I cannot launch this model at more than 300 turns and 2 inch-ounces of torque in that small park without risking its loss.

When I can test fly my beginner’s P-30 at a large flying field, I will gradually increase to 1000+ turns and 5+ inch-ounces of torque. I need to confirm that the model exhibits sufficient roll stability in windier conditions.  This may not take place for several months due to the ongoing pandemic.

Thanks for reading this post.  Your input is welcome.


Title: Re: Flat Wing P-30
Post by: flydean1 on July 19, 2020, 08:24:00 PM
One way to test at higher torque levels without exceeding small field dimensions is to double the rubber cross section.  You will have to ballast the model to keep the CG the same as with the 10-gram motor.  If you double the cross section of your present motor, the 2 oz/in torque will come up at about 75 turns.  5 oz/in will probably require less than 200 turns.

This accomplishes several things.  First, the increased motor weight and CG ballast will inhibit the glide, shortening the flight.  The higher torque will bleed off very quickly.  Any dangerous tendencies will be revealed but will be of short duration; sort of like a short motor run at full power on a gas or electric model.

I used this to trim my Majestyk to be "safe" at 6 oz/in torque knowing it will be well able to handle the 10 gram motor (2-loops of 1/8).  Best flight was still less than 40 seconds, and well contained in the small field I had at my disposal.


Title: Re: Flat Wing P-30
Post by: atesus on July 19, 2020, 09:01:02 PM
Went back to the correspondence.  Ding was flying with a club in the Sacramento area.  Searched the Endless Lift site.  No picture of the P30.

Ding Zarate is a member of Oakland Cloud Dusters. I'll let him know of this thread.

Our web site has one of his designs with tip plates, but it's a more conventional setup.

http://www.oaklandclouddusters.org/Resources/Documents/Plans/Rubber/DingZarate_equilibrium_P30.pdf

--Ates


Title: Re: Flat Wing P-30
Post by: calgoddard on November 02, 2020, 01:46:40 PM
I was finally able to put in some higher power trim flights with my Three Nite P-30 at a beautiful free flight field in northern Nevada. It is about one square mile of flat grass land with no trees.  This flying site is located west of Washoe Lake roughly halfway between Reno and Carson City. It is a landing zone for hang gliders that take off at nearby Slide Mountain (9,000+ feet at its peak).  I can fly model airplanes there seven days a week and it is only a 45-minute drive from my home.  There are no cattle on the site - indeed the area is not properly fenced to keep them from wandering away.  My guess is that the land is owned by the State of Nevada or Washoe County. So hopefully it will not be developed into housing in the future.

I gradually ramped up the torque during the trim flights and added down and right thrust as appropriate.

It was relatively easy to achieve a 2-minute max with my Three Nite P-30 even though I was flying at an altitude of approximately 5,000 feet.  Flights would be longer at sea level due to the increased air density. The performance of my Three Nite P-30 exceeded my expectations. The model has no apparent roll instability issues as some might have thought with no wing dihedral. 

Here is a link to a video of the latter part of one of the flights:
 
https://www.youtube.com/watch?v=hhxdQG2ohJ8

Sorry for the lack of visibility of the model in the video.  It was taken with a cell phone camera.

This video shows some of the glide phase of the flight. I think it catches some down air during a segment of this video because overall the glide of this model was quite good for a 45 gram “stick and tissue” P-30.

I am pleased that I achieved my goal of designing P-30 that would be relatively easy for a novice to construct and still provide reasonably good performance. I am even happier to discover a really good CAT III outdoor flying site that is close by my home and unlikely to be made unavailable for free flight for a number of years. I was the only flier at the site and probably that will be the case most of the time. In fact, I believe I am probably the first person to ever fly a rubber powered free flight airplane at this site. It is apparently rarely used for flying RC gliders.


Title: Re: Flat Wing P-30
Post by: flydean1 on November 02, 2020, 03:04:36 PM
The video was certainly convincing.  Just wondering how it would do in some typical "contest" turbulence.

You're tempting me to do a flat one.


Title: Re: Flat Wing P-30
Post by: greybird on November 10, 2020, 09:37:30 PM
I flew a Carney "designed to spec" embryo for two seasons until I lost it to a flyaway. It has a wing with tip plates and a very long fuselage. an ungainly looking airplane ,but a flying machine! it handled all sorts of weather. I was experimenting with an 8 gram motor when I lost it,
yes 4/5 of a p30 motor on 50 square inches!  that gave it an unreal climb after it sorted it's self out. Stablity in the glide was never an issue.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 14, 2021, 12:37:19 PM
Volare Products is now selling a laser-cut short-kit for my Three Nite P-30 at www.volareproducts.com.  In the process of developing and refining the short kit, George Bredehoft had me build a second prototype using the laser cut parts which he meticulously laid out on five different sheets of 1/16-inch sheet balsa wood.  The laser-cut parts went together beautifully and the build took less than half the time it took me to build the first prototype from scratch. The picture attached to this post shows my second prototype.

The two prototypes have essentially the same air frame.  The only significant difference is that the single 1/8 x 1/8-inch main spar of the wing of the first prototype was replaced with vertically spaced upper and lower main spars each measuring 1/16 x 1/8-inches.  These two spars are connected by 1/16 thick sheer webs in the middle three bays of the wing.  While there were no problems encountered with the wing of the first prototype, I felt this design change would add significant strength for minimal (if any) weight gain. Details about test flights of the second prototype and the Volare Products short kit are set forth in the following post.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 14, 2021, 12:39:22 PM
This is a continuation of my previous post.

Test flights last week proved that just like my first prototype, the second prototype of my Three Nite P-30 was easy to trim, had plenty of roll stability, and was more than capable of achieving a two-minute max. The picture attached to this post shows me launching my second prototype at Washoe Valley, Nevada, on March 7, 2021.

The glide of each of my two prototypes is surprisingly good for a P-30. This may be because the tip plates on the wing are reducing drag-generating wing tip vortices. The tip plates also apparently eliminate any need for wash-out in the wing tips. The use of the Neelmeyer airfoil may also be enhancing the glide. I understand that a 10% Neelmeyer airfoil was a favorite of Bill Henn who was very successful at SAM competitions, and later at FAC competitions.

In my exhaustive research I have yet to locate any P-30 design with a flat wing and tip plates that has previously been published and/or kitted. I am very surprised by this in view of the very good flight performance of my two prototypes.

The Volare Products short kit that is available for purchase at www.volareproducts.com includes five sheets of laser-cut parts, a very clearly laid-out full-size plan with helpful legends, and eight-pages of detailed building instructions and flying tips. The plan shows how to incorporate a simple and reliable fuse DT. There are two purchase options: $22 for the plan and laser-cut parts, and $40 for the plan, laser-cut parts, beginner’s parts (dowels, Aluminum tube motor peg, and rubber for one motor), and 9 ½-inch Gizmo Geezer prop assembly.

Look for an article about the development and details of my Three Nite P-30 in an upcoming edition of the NFFS digest.

Beginners now have a P-30 kit commercially available to them which is easier to build than any other P-30 kit or published design yet still yields a competitive rubber powered model airplane.  Accomplished fliers may enjoy the quick build of the Three Nite P-30 that will add a uniquely configured good performer to their fleets.

I hereby state for the record that I have no financial interest in sales of the Volare Products short kit for my Three Nite P-30.  My only hope is that my simple P-30 will provide another vehicle to encourage people to join our free flight hobby.

Thanks for reading my two posts today.  Your comments and feedback are welcome.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 14, 2021, 05:24:30 PM
The attached picture shows the slab sides of the fuselage constructed from the Volare Products short kit.  See Reply #42 and Reply #43 for a description of this new Volare Products short kit.

Each side is constructed from two sections that have been laser-cut from 1/16-inch sheet balsa wood. The sections are glued end-to-end with an interlocking joint and the joint is reinforced with a doubler.  Another doubler is glued over the motor peg location.

The laser-cut oval apertures save about 2 grams in weight.

The front 4-inches of the fuselage have no apertures laser-cut in the same for ease of handling the model and to provide a location for a viscous timer for the DT if that option is utilized.

The fuselage sides have been vertically oriented with their top edges held in a straight line by pressing them against and underlying section of sheet metal sheet with pairs of magnets.  I have long used this Magna-Board XL system from Easy Built Models.

Note the laser-cut notches in the upper and lower edges of the slab sides of the fuselage.  These are mounting locations for the cross-pieces.  Each laser-cut cross-piece has integral gussets at each end that are glued against the inner sides of the fuselage sides to properly space the sides apart from each other and add strength.

The laser-cut parts allow for rapid and accurate construction of the fuselage.

I'll post more pictures as this build of my third Three Nite P-30 progresses.


Title: Re: Flat Wing P-30
Post by: OZPAF on March 14, 2021, 07:47:43 PM
Interesting approach Cal. I haven't tried anything large but I have built and flown modified Darcy Whyte Squirrel's and they have surprised me with their ability to handle a 51/2" prop on a 12" WS.

I was able to trim them to get very fast and steep climbs with a decent glide.

I must admit I was surprised and originally only selected them for their simplicity when working with kids.

Best of luck with your nice looking P30.

John


Title: Re: Flat Wing P-30
Post by: calgoddard on March 14, 2021, 08:54:29 PM
John -

Thanks for the complement. I have long enjoyed your thoughtful and gracious posts on HPA that are very encouraging.

I currently have ten flyable P-30 models. What surprises me is that the glide on my Three Nite P-30 appears to be competitive with the glide of my high-tech P-30s that have high aspect ratio, under cambered wings. Those thin wings are tedious to build with CF reinforced balsa wood parts and it is not easy to cover them with Mylar film. However they do have the advantages of being very strong, very light, and basically impervious to unintended warps.

My eventual goal of this project was not to come up with a model that could challenge Buddenbohm's Air Shark, DeLoach's Polecat MK 10, Brooks' Boomer MK III, or Berdov's Pirate.

I wanted to come up with a quick-building laser-cut kit for a beginner that would be a good flier. But I now think my Three Nite P-30 would be competitive in the hands of an experienced flier. Plus I think a 9-hour build for a good flier is an attribute.  By way of example, it probably took me twice as long to scratch-build my HOT BOX P-30 (picture attached) which is another entry level P-30. I don't think my HOT BOX P-30 flies as well as either of my Three Nite P-30s. The HOT BOX has a wing with conventional V-dihedral and a flat bottom air foil.  Its wing uses cracked ribs to approximate a traditional air foil shape.

Currently I am building a third Three Nite P-30 with lighter balsa wood so that it can carry one of my RF locators without a serious weight penalty.


Title: Re: Flat Wing P-30
Post by: flydean1 on March 14, 2021, 10:19:17 PM
Ding Zarate's quote below:  I was asking him about his experience with end plates only.

Hi Dean,

Yes I have been flying a Squirrel Type P-30s since 10-10-2010 (see Endlesslift.com) and I'm still fascinated with the idea.  In one of the videos of Endlesslift I had noted a stall in that short flight.  In that stall the model came to a stop at a slant to the right.  On the downward movement after the stall the model seemed to straighten itself up to vertical again and it continued into a complete 360 and into the ground.  Now was that the effect of the wing tip  endplates or not?  Maybe?

I think Darcy Whyte has discovered something.

Ding Zarate


So Cal, you  have confirmed the concept is a valid one.  I have some garage/shop cleaning, and renewing my Instructor's Certificate.  After that, I plan a P30 from the Boomer III kit and will build it with no dihedral and end-plated.

When we see the Wakefield...er F1B gang using them you, Ding, and Darcy will be hailed ad pioneers.


Title: Re: Flat Wing P-30
Post by: Kevin M on March 15, 2021, 02:22:12 PM
I'm very interested in this. Nice design, looks good and appears very well engineered, should be a popular kit. I'm looking forward to more reports as you get to fly it more in varying conditions.


Title: Re: Flat Wing P-30
Post by: Indoorflyer on March 15, 2021, 02:51:35 PM
Looks like a nice design.  Could not find it (yet) on the Volare site.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 15, 2021, 03:06:00 PM
Dean, Kevin and Indoorflyer - Thanks for your interest and support.

George Bredehoft has been very busy filling orders lately so I guess he is a little behind getting the new Three Nite P-30 short kit listed on his Volare Products website.

I am continuing the build of my third prototype of my Three Nite P-30.  I am building my second version of the Volare Products short kit, this time using lighter balsa wood.  

The attached picture shows the completed fuselage. It weighs 7 grams.  It is probably one of the straightest box fuselages I have ever built. And no, I don't have a second gear-shaped coffee table that meshes with the one shown in the picture.

The slab sides of the fuselage are laser-cut in two sections so that the short kit is easier to ship. As shown in the attached picture, the stab platform is one triangular piece with tabs that interlock with tabs on the tail end of the fuselage sides. This makes for good alignment and helps avoid a "banana boat" fuselage.

As shown in the third picture, each laser-cut cross-piece has integral gussets at each end that serve as stops when they are glued in notches and to the inside walls of the fuselage sides. This keeps the fuselage sides a uniform distance apart.

It would simply be impractical to try to cut fuselage sides, cross-pieces and a stab platform like those in the short kit by hand. Even if you could, it would not be possible to obtain the dimensional precision yielded by laser cutting. The large ovals laser cut in the sides of the fuselage save 2 grams.  That might not sound like much, but every little bit helps in building near the 40 gram minimum weight set forth in the rules for the P-30 event as adopted by the AMA.

I will build the nose assembly and wing saddle next.  I ordered some medium density balsa wood last week so that I can strip the sticks for the LE, TE and spars. The shipment from the supplier is supposed to arrive this week. The balsa wood in my current inventory is either too light (7# or less) or too heavy (12# or more).

Thanks for following this third build.


Title: Re: Flat Wing P-30
Post by: Bredehoft on March 16, 2021, 12:56:39 PM
It is online now  :)

--george


Title: Re: Flat Wing P-30
Post by: calgoddard on March 17, 2021, 03:59:13 PM
The attached picture shows the frame of the wing of my third Three Nite P-30.  My shipment of balsa wood arrived early. The weight as shown is 6.7 grams. Note the three sheer webs connecting the upper and lower main spars in the three center bays of the wing.

I have been using the term "prototype" too loosely.

My original scratch-built Three Nite P-30 was a prototype. That model is shown in an earlier post in this topic.  It blue, yellow and red.

My second build was a test build of the Volare Products laser-cut short kit. That blue and yellow model flew OOS on its fourth trim flight. The DT was operating and was set for a little over two minutes.  2 1/2 hours of searching by me and my wife were not successful in locating that model.

I am currently building a third Three Nite P-30 using a Volare Products short kit to replace my recently lost model.  It is being built with lighter wood.

Technically the second and third Three Nite P-30s are not prototypes since they have the same basic design as the first one that proved the concept.


Title: Re: Flat Wing P-30
Post by: billdennis747 on March 17, 2021, 05:19:52 PM
I like the geared table. Are there several interlocking across the room? You could sit at one end and rotate the soup at the other


Title: Re: Flat Wing P-30
Post by: PeeTee on March 17, 2021, 05:48:59 PM
 ;D ;D

Cheers!


Title: Re: Flat Wing P-30
Post by: flydean1 on March 17, 2021, 09:08:26 PM
Trackers!!!


Title: Re: Flat Wing P-30
Post by: calgoddard on March 18, 2021, 03:22:56 PM
I have owned and used the Walston RF tracking system successfully for many years.

I have a frequency A transmitter and a frequency B transmitter in case someone else is flying at the field with a similar system.

Unfortunately, I did not mount one of my RF transmitters onboard my second Three Nite P-30 that flew OOS on March 7, 2021.

That model weighed 45 grams and I wanted to observe its performance without the additional 3-4 grams represented by a Walston RF transmitter and batteries.

I am building a third Three Nite P-30 that will be lighter.  I won't fly it without an RF transmitter on board.


Title: Re: Flat Wing P-30
Post by: flydean1 on March 18, 2021, 06:10:11 PM
Not meaning to seem like a jerk re: trackers.  I won't test glide without one!  One question:  What type of DT?  Tip up tail, tip up wing, or wing pop-off?  The only genuinely successful DT I have used on a P30 is the pop-off wing.  There is a down side of potential front end damage if it hits on a road or rock, and sometimes the line retaining the wing gets badly hung-up in foliage. 

Clint Brooks has worked out a combo system of pop-up wing and tail, which seems to work well.  It would defeat your purpose of a simple-to-build model.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 18, 2021, 07:11:21 PM
flydean1 -

No worries. I appreciate you following along and making helpful comments.  I have learned my lesson now and will always load one of my RF transmitters on board any model large enough to endure the weight penalty.  I have a brand new scratch-built coupe that has a nice little box built right over the CG inside the fuselage that will accept one of my Walston RF transmitters.  The box has plenty of clearance relative to the wound 12 x 1/8 rubber motor. It has not yet been flown but I will absolutely install and RF transmitter in it before its first trim flights. I have a standard practice of checking the batteries in a battery checker before installing them in the RF transmitter.  I then hook up the antenna to the receiver and confirm that I am getting a beep-beep-beep before I launch.

My second Three Nite P-30 had a pop-up stab DT. I know that this will sometimes not prevent a P-30 from being carried away by a strong thermal.

I have combination pop-up wing and pop-up stab DTs on my two "high-tech" P-30s shown in the attached pictures. They are my own design. These DTs are too complicated for a beginner.  But these P-30s are at or slightly below the 40 gram minimum and need protection from strong thermals. The weight of the RF transmitter counts toward the 40-gram minimum in the rules so they are both legal if flown with an RF transmitter on board.

If you use a combination pop-up wing and pop-up stab DT the model descends gently in horizontal orientation with no risk of damage to the prop or front end of the fuselage.

I have one P-30 with a pop-off wing DT.  I am not a big fan of that arrangement because of the rapid nose-down descent and the risk of a bent prop shaft.

The Volare Products plan for my Three Nite P-30 shows a pop-up stab DT activated by a fuse. This is the simplest DT to implement and is very reliable so long as you remember to light the fuse.


Title: Re: Flat Wing P-30
Post by: DerekMc on March 18, 2021, 07:35:48 PM
flydean1 -

I have one P-30 with a pop-off wing DT.  I am not a big fan of that arrangement because of the rapid nose-down descent and the risk of a bent prop shaft.


Has the bent prop wire happened? I've had 50+ flights with a pop off wing dt without a bent prop wire. Many of the dt's were on hard ground.


Title: Re: Flat Wing P-30
Post by: flydean1 on March 18, 2021, 10:30:36 PM
Cal, I know about the unlit fuse.  Lost a Viking as a kid by forgetting to light it.

I go through the same drill pre-flighting my Walston system.  One difference;  I do the initial check with no antenna, just the receiver only and with the attenuator ON.  Jim Walston gave me that suggestion just as I was first using his system (I miss that guy).  He said that at very close range you should get the beeps.

Another trick Joe Clawson showed me after I dropped one of my transmitters in tall grass.  I use yellow balloon sections to hold the batteries in.  Still disappeared.  Joe told me to disconnect the antenna and use the wire sort of as a sounding tool.  It got me within a couple feet.  Believe it or not, I spotted the antenna wire first.  Looked like a grass stem out of place.

If I could afford it, I would go to the newfangled GPS systems.  However, with a good compass line, county road map, and my Walston I do pretty well.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 19, 2021, 11:32:58 AM
Derek -

No, I have not suffered a bent prop shaft on my P-30 with a pop-off wing DT.

I have attached a picture of that model.  I named it my Holiday P-30 as it was quickly built about five years ago during the Christmas holiday to test how the pop-off wing DT works.  It is my own design except that I did use the wing ribs and wing plan from a One Nite 28 kit.

I have not flown my Holiday P-30 very much but the pop-off wing DT seemed to work fine.  The straight down rapid descent concerned me because of the hard pack dirt around the flight line in Perris, CA. I now prefer the pop-up wing and pop-up stab DT.

My Three Nite P-30 is intended to be a quick build for both beginners and experienced fliers.  The fuse activated tip-up stab DT shown on the Volare Products plan is the simplest and most reliable DT around.  Yes it is inadequate if the model encounters a strong thermal.  However, I don't want to present a beginner with the challenge of implementing a pop-off wing DT.  Securely anchoring rotating fishing lures mid-chord on one wing tip and to the tail end of the fuselage, and with the proper length of fishing line strung over the top of the horizontal stabilizer may be daunting tasks for a beginner.

I wish to take this opportunity to thank you for creating and updating your P-30 website.  It is a very nice resource.  Do you think you could add the Three Nite P-30 to your P30 Page? I will fill out and submit your contact form. Thanks in advance.

_____________________________________


flydean1 - Thanks for those excellent tips about use of the Walston retrieval system. I was not aware of them and they could come in handy.


Title: Re: Flat Wing P-30
Post by: DerekMc on March 19, 2021, 06:12:33 PM
Derek -

I wish to take this opportunity to thank you for creating and updating your P-30 website.  It is a very nice resource.  Do you think you could add the Three Nite P-30 to your P30 Page? I will fill out and submit your contact form. Thanks in advance.

Your welcome. Yes, lets set up a page for your new P30. It's a cool plane. I plan on ordering one soon. I'll respond to your email shortly!


Title: Re: Flat Wing P-30
Post by: DerekMc on March 20, 2021, 05:04:05 PM
Here's a link to Calgoddard's Three-Night P30 on The P30 Page.    Cool Plane Mike!

http://p30page.weebly.com/three-night-p30.html (http://p30page.weebly.com/three-night-p30.html)


Title: Re: Flat Wing P-30
Post by: DerekMc on March 20, 2021, 07:23:43 PM
I did a bit of editing on the Three Nite P30 page so the link shared above doesn't work any more.  Here's a link that works-

http://p30page.weebly.com/three-nite-p30.html (http://p30page.weebly.com/three-nite-p30.html)


Title: Re: Flat Wing P-30
Post by: Indoorflyer on March 20, 2021, 07:54:31 PM


I hope to fly a P-30 at Lost Hills this year.  Kind of a bucket list thing I want to check off.  The "Three Night" really appeals to this P-30 newbie...


Title: Re: Flat Wing P-30
Post by: flydean1 on March 20, 2021, 09:37:46 PM
Well, I took the bait.  Despite having 2-1/2 P30 kits (Built Majestyk wing and tail counts for 1/2), I ordered myself a 3-Night P30 Kit from Volare.  Just felt like supporting the effort and I have someone in mind that it would be a good starter model.


Title: Re: Flat Wing P-30
Post by: lincoln on March 21, 2021, 12:59:35 AM
That gear table looks like it could use string as a clamp for something that needs to be held down, though maybe something larger. Maybe a smaller, rectangular one would be good for fuselages.

My Walston was easy to find when it had a fresh battery and was secured in a model. However, without the battery and outside of a model, I can't find it. It might be someplace in my car. Who knows?


Title: Re: Flat Wing P-30
Post by: calgoddard on March 21, 2021, 06:13:52 PM
There is a reduced copy of the Volare Products plan for the Three Nite P-30 in Derek's excellent P30 Page website. The link that will take you there is set forth in Reply #64. You will need to scroll down a bit.

If you scroll down in the article you can see a photo of the scratch-built prototype.  It has a red 9 1/2-inch Czech (Igra) prop instead of a 9 1/2-inch Gizmo Geezer prop assembly.  The latter is recommended for beginners.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 22, 2021, 04:25:11 PM
Here is a picture of the completed frame of the horizontal stabilizer. It was built with the laser-cut ribs from the Volare Products short kit.

The weight as shown is 1.92 grams.  I like the covered stab of a P-30 to be around 3 grams. We'll see what this one weighs after covering with Esaki tissue.

The dimensions of the stab are 12 3/4-inches x 3 inches.  That includes the sheet balsa wood fins which are laser-cut from 1/16-inch sheet balsa wood.

The fins will be glued to the outermost ribs after the stab is covered.

The can of chicken gravy was included in the picture to give you an idea of the scale of the stab.


Title: Re: Flat Wing P-30
Post by: calgoddard on March 24, 2021, 05:21:03 PM
Here is a picture of the completed bones of my 2nd build of the Volare Products short kit for my Three Nite P-30.

The weight as shown is 31.40 grams. That includes the weight of two # 16 office rubber bands that are temporarily holding the wing saddle to the fuselage.  When the model is completed, the longitudinal position of the wing saddle will be adjusted (with a rubber motor installed) to set the CG at the optimum location.  The wing saddle will then be glued in place.

The tip plates have been tack glued to the outer wing ribs for illustration purposes.  The tail fins have been tack glued to the outer stab ribs for illustration purposes. The tip plates and tail fins will be removed to make it easier to cover the wing and stab with tissue.

I will paint the tip plates and tail fins with flat black Design Master floral spray paint. It is very light weight and gives a moisture-proof coating.  Plus, I like the way black tip plates and tail fins look on the model when it has been covered with tissue.


Title: Re: Flat Wing P-30
Post by: duration on March 25, 2021, 05:55:37 AM
Don't use black for rudders, or, in this case the tip plates. White shows up much better against a dark tree line. (If you fly in California you can ignore this.)

Black is great on the underside of the wing since it offers a strong contrast against a light sky.  A bit of day glow red, orange, or pink on the upper wing tips really helps visibility in tall grass.

I try to use the same color scheme for all my models so I can easily recognize them at a distance.

Louis



Title: Re: Flat Wing P-30
Post by: calgoddard on April 02, 2021, 03:27:34 PM
I finished the build of my third Three Nite P-30.  I have been busy with other projects.

This model was built from the Volare Products short kit and replaces my blue and yellow version that flew OOS. See Reply #42. That model was also built from the Volare Products short kit.

I took the advice from Louis and painted the tip plates and tail fins red.

The weight is of this build is 40.2 grams.  The short kit I used in building my third Three Nite P-30 included lighter sheet wood. The Walston RF transmitter and its batteries will add about 3 grams.

This model has a tilt up stab DT, like its two predecessors.  I know that it will not come down in a strong thermal.  This is a beginner's design and I don't want the complexity of a pop-up or pop-off wing DT.

I will have to wait at least another week for the winds to decline at my local flying site.  I want the winds to be under 4 mph for trimming.

While my goal was simplicity in the build, flights of my prior two Three Nite P-30 models showed that this design is easily capable of achieving a two-minute max under the P-30 rules.

I have screwed in 5 degrees of down thrust and 2 degrees of right thrust into the Gizmo Geezer prop assembly and will make further thrust line adjustments during trim flights, if needed.





Title: Re: Flat Wing P-30
Post by: Olbill on April 02, 2021, 04:58:29 PM
I think you should call it the Finny-30 b/c it looks so much like the early Finny planes.


Title: Re: Flat Wing P-30
Post by: USch on April 02, 2021, 05:09:55 PM
Beautiful plane and beautiful lake.
Why not fit a pair of float's and try a ROW ?

A good example that sometimes experimenting is more worth than long discussion. You did a great job Calgoddard, compliments.

Urs


Title: Re: Flat Wing P-30
Post by: OZPAF on April 03, 2021, 01:26:14 AM
Definitely agree! What a beautiful setting and I would think you have achieved your goal!

John


Title: Re: Flat Wing P-30
Post by: calgoddard on May 02, 2021, 08:54:59 PM
Thank you John and Urs for your kind words.

There was a calm morning at Washoe Lake, Nevada, On April 19, 2021.  So I went flying.

I flew my third Three Nite P-30 (red and yellow) for the first time.  This is the second one I built from the Volare Products short kit.  As you know, my first build of the Volare Products short kit (blue and yellow) flew OOS and was lost.

After a few trim flights, I wound the 12 x 1/16-inch motor to 1200 turns and 7 inch-ounces of torque.  The model rolled a bit to the left shortly after being launched due to the high torque, but recovered.  It DTed at 3 minutes and twelve seconds about 75 feet above the ground.  It could have been a flight close to four minutes but for the DT.  It may have caught some good air way up high.  On the other hand, the torque roll at the beginning of the launch surely cost the model some significant altitude.

See the attached pics.

This time the model was carrying one of my Walston RF transmitters - so the AUW was probably around 45 grams (not counting the rubber).  Naturally, the RF transmitter was not needed as the chases were short and the model easily retrieved by sight. This was the fifth wind of the rubber motor but the prior winds were something like 100, 300, 500 and 850.  I had taken out a slight amount of right thrust (maybe 1/2 degree) prior to the last flight because the model had been turning a bit tight to the right in the power phase.  I can either put that right thrust back in, or fly with a 10 x 1/16-inch rubber motor which can't take much more than 6 inch-ounces of torque but gives you a longer motor run.

Again, no lateral instability issues with this design were detected. So, the tip plates apparently eliminate any need for conventional dihedral and wing tip wash out.

Thanks for all of you that have read my posts on the development of this model and given me your support. I have around ten P-30 models, some of which are very high-tech.  The rudimentary design of my Three Nite P-30 has proven to be a good performer in my flights of three of them that I have built.  For some reason the glide of this design seems particularly good for a P-30. I am guessing that the good glide performance has something to do with the tip plates reducing wing tip vortices that induce drag.



Title: Re: Flat Wing P-30
Post by: Olbill on May 03, 2021, 12:38:37 AM

 For some reason the glide of this design seems particularly good for a P-30. I am guessing that the good glide performance has something to do with the tip plates reducing wing tip vortices that induce drag.


I think there are a number of indoor duration classes that have benefited from this layout: LPP, F1M, Ministick, Wright Stuff. I'd like to build a competitive A6 like this. I actually started out in A6 with a flat wing/tip plates model, but the prop I was using then was inferior to current ones.


Title: Re: Flat Wing P-30
Post by: OZPAF on May 03, 2021, 09:13:50 PM
That's a rewarding result Cal. Perhaps a slight increase in the height of the wing tip plates would help to reduce the torque roll on launch with the more powerful rubber - effectively increasing the dihedral effect.

Anyway you certainly have developed an interesting model.

John


Title: Re: Flat Wing P-30
Post by: calgoddard on June 07, 2021, 04:49:24 PM
For those of you who are members of the National Free Flight Society (NFFS) the just published May - June 2021 edition of the NFFS digest contains a copy of an article I wrote about my Three Nite P-30 design.  The article includes a reduced view of the plan from the Volare Products laser-cut short kit.

I hope that NFFS members will suggest this kit to those interested in exploring our hobby for the first time.


Title: Re: Flat Wing P-30
Post by: calgoddard on June 14, 2021, 10:33:47 AM
On June 13, 2021 I flew my red and yellow Three Nite P-30 in the John Oldenkamp Memorial P-30 contest held at Taibi Field in Perris, California.  John was a co-originator of the P-30 event.  See the attached picture of me launching my model on one of my official flights in this contest.  My P-30 that is shown in this picture was built from the Volare Products short kit.

Thirteen experienced P-30 fliers flew in this event including two of the three very best P-30 fliers in the US. I chose to enter my red and yellow Three Nite P-30 to see how it would stack up against very stiff competition and, frankly, just to fly a different looking P-30 design.

Flying conditions were near perfect with 2-3 mph winds and lots of lift. After the initial round of official flights, five of the thirteen fliers had achieved three 120-second maxes under the AMA’s rules for the P-30 event, including me.
 
Per the AMA rules, a fly off ensued with increasing max times of 150, 180, and 210 seconds.

Two fliers made it to the third round of the fly off, including myself. I ended up being the winner of this memorial P30 event. I was only officially credited with a sixth flight time of 195 seconds as that is when my timer (my wife) lost sight of my model.  However, my daughter was chasing for me and she reported an official flight time via her cellular telephone of just short of five minutes.
 
On all of its official flights my red and yellow Three Nite P-30 was carrying one of my Walston RF transmitters with batteries. That was a weight penalty of around 5 grams. As is often the case, it turned out that the onboard RF transmitter was not needed to facilitate any of the long recoveries. Had my model not been carrying an RF transmitter it would have flown even better, but the odds of losing it would have probably gone up dramatically.

This is not to say that the design of my Three Nite P-30 is better than any other existing P-30 design.  In truth, by way of example, Stan Buddenbohm’s Air Shark and Clint Brooks’ Boomer MK III are probably superior P-30 designs in terms of performance. However, even a beginner’s P-30 design that is a quick build, like my Three Nite P-30, can be very competitive in the P-30 event. Of course, as in any flying contest, you need a bit of good luck on your side in order to prevail.  On another day, a different one of these fliers may have won the contest.


Title: Re: Flat Wing P-30
Post by: Olbill on June 14, 2021, 11:16:18 AM
Excellent results. Congratulations!


Title: Re: Flat Wing P-30
Post by: OZPAF on June 16, 2021, 08:43:39 PM
Congratulations Cal. Definitely the proof of the pudding.

John