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Author Topic: Flat Wing P-30  (Read 3623 times)
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OZPAF
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« Reply #75 on: April 03, 2021, 01:26:14 AM »

Definitely agree! What a beautiful setting and I would think you have achieved your goal!

John
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calgoddard
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« Reply #76 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.

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Re: Flat Wing P-30
« Last Edit: May 02, 2021, 09:07:37 PM by calgoddard » Logged
Olbill
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« Reply #77 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.
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OZPAF
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« Reply #78 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
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calgoddard
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« Reply #79 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.
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calgoddard
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« Reply #80 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.
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Re: Flat Wing P-30
« Last Edit: June 14, 2021, 11:58:21 AM by calgoddard » Logged
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« Reply #81 on: June 14, 2021, 11:16:18 AM »

Excellent results. Congratulations!
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OZPAF
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« Reply #82 on: June 16, 2021, 08:43:39 PM »

Congratulations Cal. Definitely the proof of the pudding.

John
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calgoddard
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« Reply #83 on: June 25, 2021, 07:19:51 PM »

Thanks Bill and John for your congratulations on my contest win.

Here is a close-up picture of my third Three Nite P-30. I won the John Oldenkamp Memorial P-30 contest on June 13, 2021 flying this model.  See Reply #80 for details of the contest. This picture is better than the pre-flight picture shown in Reply #72 because this picture shows the position of the wing that located the CG at 60%.  This position is significantly further forward than the position of the wing shown in the picture in Reply #72.  After adjusting the wing longitudinally on the fuselage, the longitudinal rails of the wing saddle were glued to the upper edges of the slab sides of the fuselage.
  
Note that the wire antenna of the onboard Walston RF transmitter is extending rearward from underneath the central bay of the wing. I thread the rearward end of this wire antenna through the rubber bands that tilt up the stab to hold the wire antenna in place. The transmitter fits snugly in a small balsa wood box is that is glued to the wing saddle.  The box is located so that the weight of the transmitter and its batteries is evenly distributed over the CG.  This allows me the option of flying the model without the transmitter onboard while not altering the trim.

The weight of this P-30, not counting the transmitter, batteries, transmitter box, and rubber motor, is 40.2 grams. This weight was achieved building the model from the Volare Products laser-cut short kit. The sticks that I used for the LE, TE and spars of the wing and stab were stripped from 1/16-inch and 3/32-inch - 7-8# density balsa wood sheets.

On all six of its official flights during the June 13, 2021 contest my red and yellow Three Nite P-30 was carrying a Walston RF transmitter and batteries. This resulted in a weight penalty of approximately 5-grams (counting the weight of the balsa wood box). Having permanently lost its blue and yellow predecessor OOS, I vowed not to fly my third Three Nite P-30 without an RF transmitter on board.

The wing of this P-30 has locating keys on the underside of its central bay to ensure that the tip plates maintain the same alignment from flight to flight. The stab also has keys located on its underside to ensure proper alignment of the twin fins.

The pulling force on the viscous timer of the DT and the pulling force on the TE of the stab are separated by use of a pivoting arm made of .031-inch music wire.  This “mouse trap” arrangement avoids stab creep and stalling that can occur if the same rubber band is used to hold down the stab and pull on the lever arm of the viscous timer. An article published in the December 2004 edition of the Scale Staffel FAC club newsletter credits the mouse trap design to John Oldenkamp. Here is a link to that article: https://freeflight.org/Library/TechLibrary/DTButtonMounting.pdf

I hope that these additional details are helpful.

Thank you for your continued interest in this topic.  It has been a fun journey.
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Re: Flat Wing P-30
« Last Edit: June 25, 2021, 07:35:15 PM by calgoddard » Logged
OZPAF
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« Reply #84 on: June 26, 2021, 02:18:44 AM »

That tail moment looks better to my  eyes Cal. Thanks for the extra info. The "mousetrap" approach looks interesting but I'm curious if it would be any better than a simple friction post to isolate the timer from the tail DT line?

John
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calgoddard
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« Reply #85 on: June 26, 2021, 11:23:27 AM »

John -

Your last post in this topic raises an excellent question.

I have, on many occasions, used a peg or "capstan" to isolate the pulling force on the viscous timer from the stab hold down force.

This article gives the details:

http://www.flyingacesclub.com/PFFT/DTSetupUsingButtonTimer.pdf

I have found the mouse trap arrangement to be superior.  

It is tedious to wrap the DT line around the capstan while ensuring that the TE of the stab is fully down. Then it is tricky to get the loop on the front end of the DT line over the lever arm of the viscous timer without the stab tilting up a tiny bit. Sometimes I have to tug on the DT line where it wraps around the capstan and pull down on the stab at the same time to ensure that the stab is fully seated and the decalage is what it should be.

The mouse trap arrangement allows the use of very robust force for tilting up the stab, and a very robust force for holding down the stab.  This ensures that the stab will be held down firmly, and will smartly pop-up when the DT triggers, even in very breezy conditions. I have found it difficult to mimic this dynamic using only a capstan, and therefore tend to only use that configuration on small models like Embryos and others with a wing span of 24-inches or less.  

Of course the mouse trap DT doesn't look good on a scale model so I would not use it there.  I don't build many scale models, and when I do, I now leave off a DT for aesthetic reasons.  Here is a picture of the 2X Walt Mooney Embraer Ipanema crop duster I built for WESTFAC VIII to be held in Buckeye, Arizona this October.  With the weight and drag of landing gear, flights of this model lasting over one minute will probably be rare. If this model catches a thermal and files OOS, maybe I can still recover it.  We will be flying over green alfalfa so this yellow colored model should be very visible. There is room for one of my Walston RF transmitters in the removable wing.  If this model flies well and thermals are present, I may insert an RF transmitter which will dramatically increase the odds of recovery.

I am a better flier than a builder because I am not an artist.  I lack the patience and skill necessary to build to museum quality. But from a distance I think my scale models look decent.  I fly a lot of P-30, F1G and OTR models, aiming for maxes. Their looks generally don’t matter although I like them to show a reasonable amount of good craftsmanship in case another flier sees them close up.
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Re: Flat Wing P-30
« Last Edit: June 26, 2021, 11:41:30 AM by calgoddard » Logged
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« Reply #86 on: June 27, 2021, 01:47:55 AM »

Thanks for the update Cal. Yes that all makes sense and your link is what I was referring to.

I am also not a museum quality builder - ie when I am known to build Smiley and actually I fly more RC F5J glider than anything else, but do have a interest in rubber duration and CLG and their trimming techniques.

Your Mooney Cropduster may surprise you!

Happy Flying.

John
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« Reply #87 on: July 23, 2021, 03:18:47 PM »

Attached is a picture of my red and yellow Three Nite P-30 shortly after it was launched at a recent fun fly in Nevada.

The model is climbing at an angle of slightly more than 45 degrees.

I recall reading a scholarly analysis in the FFQ digest that said that anything more than 70 degrees is not efficient for a rubber powered model (unless you use VIT in an F1B or F1G, for example).

I fly this P-30 with a 10 x 1/16-inch rubber motor so I have less torque to tame at near full turns. With this rubber motor cross section, I can achieve a significantly longer motor run than with the traditional 6 x 1/8-inch rubber motor often used with P-30 models. This Three Nite P-30 does not climb as steeply as the P-30s flown by some of my competitors who almost all seem to fly with a 6 x 1/8-inch rubber motor.

If my Three Nite P-30 encounters a downer it sometimes has enough turns left on the rubber motor to climb back to a reasonable altitude and still achieve a max.

Of course, in free flight the object is to get the model as high as you can and then get a good glide to maximize your flight time.  A steep corkscrew climb pattern is desirable.

Here is a link to a video taken the same day showing a max flight, seemingly without the aid of any thermal.  The video was taken with a cell phone camera so the model is a bit difficult to see in the latter stages of the glide.  Use the full screen mode on Youtube and you can see the model a little better.

https://www.youtube.com/watch?v=E0nvnJptVLU

My Three Nite P-30 in the video is being flown with around a 5-gram weight penalty (approximately 12 percent) due to the RF transmitter and batteries being carried on board.  As often seems to be the case, all the landings were easily located by sight during this partial day of flying and the RF locator was not needed.
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OZPAF
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« Reply #88 on: July 23, 2021, 09:50:12 PM »

You couldn't ask for much more than that Cal. Max flight and only 200yds or so to the landing. Magnificent scenery and even long grass to land in.

John
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« Reply #89 on: July 24, 2021, 10:12:15 AM »

Cal you sure know how to design, build , and fly . Congratulations on an amazing P-30.
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Kevin M
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« Reply #90 on: July 24, 2021, 01:55:39 PM »

Quote
You couldn't ask for much more than that Cal. Max flight and only 200yds or so to the landing. Magnificent scenery and even long grass to land in.

Absolutely, very nice to watch.
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