Hip Pocket Builders' Forum

Indoor Free Flight Forum => A-6, P-24 => Topic started by: Wout Moerman on February 23, 2015, 08:04:14 AM



Title: A6 rules?
Post by: Wout Moerman on February 23, 2015, 08:04:14 AM
Hi all,

Is it true that A6 now accepts film covering? I have the rules I've found quoted beneath, are these the most recent? I ask this because I want to introduce this class in the Netherlands as beginners class and want to have a proper start.
And is there a definition af "stabilizer" somewhere? I can see a canard in which I define the canard wing as wing and the rear wing as stabilizer, but I think this is not allowed.... But how is this excluded?

Quote
26. A-6. For event (222 )
26.1. General. Except for the specific rules which apply directly to A-6, the rules for Free Flight Indoor Rubber, Hand Launched Stick model shall apply.
26.2. The model shall be rubber powered and covered with paper or commercially available plastic; no microfilm allowed.
26.3. The total maximum projected wing area shall be 30 square inches. There is no restriction on the stabilizer area.
26.4. All wing, stabilizer and rudder wood including wing posts shall be 1/16” square wood minimum, except ribs shall be 1/32” X 1/16” minimum. Posts may be rounded in the area of the mounting tubes.
26.5. The motor stick shall be from solid wood of 6” maximum length measured from the front thrust bearing face to the front of the rear hook.
26.6. The propeller shall be 6” maximum diameter with flat blades from balsa no thinner than 1/32”.
26.7. The minimum weight of the model shall be 1.2 grams without rubber motor.
26.8. No special materials such as boron, carbon fiber or foam are to be used.


Title: Re: A6 rules?
Post by: adanjo on February 23, 2015, 08:52:20 AM
Hi all,

Is it true that A6 now accepts film covering? I have the rules I've found quoted beneath, are these the most recent? I ask this because I want to introduce this class in the Netherlands as beginners class and want to have a proper start.
And is there a definition af "stabilizer" somewhere? I can see a canard in which I define the canard wing as wing and the rear wing as stabilizer, but I think this is not allowed.... But how is this excluded?

Visit AMA website.
http://www.modelaircraft.org/events/compreg.aspx

As a rule of thumb, larger wing is wing and smaller one is stabilizer.

Aki


Title: Re: A6 rules?
Post by: Wout Moerman on February 23, 2015, 09:02:02 AM
Aki,

Thanks. I think I found the definition of wing here:
3. Area of Supporting Surface(s).
The projected area of a supporting or stabilizing surface is the area seen when looking directly down on the surface. Supporting surface area enclosed in a fuselage or stick shall not be considered as wing area. Projected area of horizontal stabilizing surface(s) in excess of 50 percent of the projected area of the supporting surface (wing area) shall be considered as wing area.


Title: Re: A6 rules?
Post by: Hepcat on February 23, 2015, 09:23:07 AM
Wout,
I was just going to quote to you what you have shewn in reply #2.  Can I assume that you have noticed that the A6 rules (presumably) override this rule and allow unlimited stabilizer area.  So, as you say, in a Canard, where the foreplane is the stabilizer the foreplane can apparently be of any size and the rear (or tail) plane is limited to 30 square inches.

I suppose I had better give the rules another read!

John


Title: Re: A6 rules?
Post by: Olbill on February 23, 2015, 10:14:38 AM
The specific rule for the stabilizer in the AMA A6 rules allows unlimited stabilizer area. This overrides the general rule about stab area in excess of 50% counting as wing area. The canard question is a little murky and would be up to the CD of an event. If I were CD I would count the larger surface as the wing.

And yes, plastic film is at long last legal for A6. For my recent builds I used 6# wood for my wing and tail spars.


Title: Re: A6 rules?
Post by: Wout Moerman on February 24, 2015, 03:15:11 AM
I'm not really planning to build an A6 with a stabilizer bigger than the wing. But in my work I often have to interpret legislation and try to spot and repair loopholes. So therefore I noticed this vague area in the rules.
I will translate these rules into Dutch and probably will add something like "the biggest lifting area will be considered to be the wing"

The good thing about using film covering is that we can use plastic sandwich bags as covering, which is so much easier to buy than condenser paper or Esaki.


Title: Re: A6 rules?
Post by: Tapio Linkosalo on February 24, 2015, 05:36:29 AM
Instead of sandwich bags, you might try the thin plastic sheet sold on hardware stores used to protect objects while painting. The funny thing is that the cheaper variety you pick the thinner is the material, so here actually (for our purposes) the cheaper is the better! The plastic is lighter than Esaki tissue, maybe 6 to 8 grams per sq meter.



 


Title: Re: A6 rules?
Post by: Olbill on February 24, 2015, 09:45:37 AM
I'm not sure what's available in other areas but here in the states the lightest film (other than specialty film made for models) I found was veggie bags from Kroger stores. These were only slightly heavier than the very best condenser paper. I have them listed at 4mg per square inch which I believe converts to 6.2 g/sq meter.


Title: Re: A6 rules?
Post by: Tapio Linkosalo on February 26, 2015, 09:28:21 AM

The protective plastic sheet that I bought from the "Bauhaus" hardware store (a major chain in Europe) has 10 square meters of plastic, weights 58 grams and costs one euro (!). I calculated that it makes 3.7 mg per square in?


Title: Re: A6 rules?
Post by: Wout Moerman on February 26, 2015, 04:03:12 PM
I now have a sandwichbag that weighs 10 grams per square meter. That is 0.3 gram on the A6 I'm designing. Tapio, that means your sheet is only 5.8 grams per square meter! I'll look around in our building supply shops.


Title: Re: A6 rules?
Post by: Olbill on February 26, 2015, 07:03:29 PM
The best CP I've ever had is 3.6mg/si. Either of the films mentioned should work well. They won't solve the problem of needing really light wood to make the minimum weight but they will solve the former problem of finding light condenser paper. The ultimate covering material for A6 is OS film. My new ones made the minimum weight even with 6# balsa for spars.


Title: Re: A6 rules?
Post by: Wout Moerman on March 01, 2015, 04:11:01 PM
I am on my way building my A-6 design. i have the wing, stab, rudder and motorstick finished, together it weighs 0.48 gram. Still need the tailboom, prop and prophanger and covering. If the covering weighs 0.3 gram I still have 0.42 grams to spend on the prop&hanger and tailboom. No idea if I can make it that light. What are usual weights for an A-6 prop?


Title: Re: A6 rules?
Post by: Olbill on March 01, 2015, 07:12:45 PM
Mine average about 200mg.


Title: Re: A6 rules?
Post by: cglynn on March 23, 2015, 09:58:17 PM
Bill, that is an impressive weight for the prop.  This past weekend I built my first A6 and found the prop to be the biggest PIA of the whole build.  I am simply not used to making a prop out of thick sheet balsa.  When it was all said and done, my prop ended up around 240mg, including the two repairs to the prop spars required after a few test flight bumps.  While I much prefer formed props for F1L and LPP, I am looking forward to flying A6.  My first one came out to 1.250 g and I know where I can save for the next one.  My current tailboom is a bit on the heavy side.  Other than that, I am happy with how it turned out.  I cannot thank enough those who pushed for plastic in A6.  It makes building to weight so much more accessible to those with lesser materials.  Light wood is easy enough to find, but light C paper, not so much.  With the ability to use plastic covering, anyone who has built a few indoor models before ought to have light enough wood to make weight.

Anyone who has been thinking of getting into A6 but hasn't because of the C paper requirement, time to get building.  The 1/16 sq sticks make building about as easy as it gets.  For my model, I honestly didn't weigh any of the pieces until I got to the prop.  By that time, I realized my prop was too heavy, but I used the lightest 1/32 I had, so wouldn't really be able to get too much lighter.  I can live with an extra 50mg on this one.  Bottom line, if you are looking for another event to challenge yourself with, that isn't exhausting or too time consuming to build, give A6 a try.

Chris


Title: Re: A6 rules?
Post by: Wout Moerman on March 25, 2015, 04:33:15 PM
Here is my A-6 design, which is based on the "Wortel". This is a famous Dutch design which is also translated into English under the name Flooper. Wortel is Dutch for root and can be either a carrot or a square root. I don't know which root the designers originally had in mind. Someday I'll ask them. It is based on the Dart but was sized up and made to perform more like a contest indoor model. Mine is scaled down to about 2/3 of the original size but the dimensions are somewhat altered to comply with the A-6 rules. Mine came out 0.1 gram underweight and was covered in sandwich bag plastic of 6.7 g/sq.m.

The first version didn't fly well. It cruised reasonably well but I wasn't able to get it to climb. I blamed this on the small amount of dihedral of the Original Wortel combined with the large flaring prop of the better A-6 designs. I increased the dihedral and made a new prop. This prop is not flaring, has a smaller blade area and a 35 degrees blade incidence. Now it climbs nicely in my too small living room. Coming Saturday I'll be flying in a big hall and will see what it does now.



Title: Re: A6 rules?
Post by: julio on March 27, 2015, 01:52:47 PM
Wout

I googled “Wortel” looking for images of the original design. Found a lot of images of non-flying designs, all of them in a nice orange color.
I finally refined the search looking for the “Flopper” and found the model you based your A-6. It’s interesting to see you choose a different path from the usual designs in your particular A-6. It has the beauty of the simple. It’s also interesting the little change from the “standard(s)” A-6 props, as you mentioned, after the test flights of your first model version and how you improved the model behavior since then.
I hope you have good results this Saturday or the day you can test fly the model. Maybe you have a just for fun model or a competitive one. Please, post your results :).

Julio


Title: Re: A6 rules?
Post by: craig h on March 27, 2015, 09:06:51 PM
What size (thickness) of rubber is usually used and size of prop hanger...I would like to try to build one of these.
I assume you can get supplies from indoor model supplies .

Thank you..


Title: Re: A6 rules?
Post by: cglynn on March 28, 2015, 02:44:55 PM
Craig, I used an EZB/F1D Harlan bearing for my prop hanger.  Rubber sizes I have seen range from around .035" to .050".  I know Harlan's Indoor Model Specialties has the bearings, and you may check out www.donsrc.com for custom stripped rubber.  It is run by Don Slusarczyc, a Cleveland area free flighter and frequent poster to the forums.  He will get you what you need.

Hope that helps.
Chris


Title: Re: A6 rules?
Post by: Wout Moerman on March 29, 2015, 11:09:30 AM
I have flown my Wortel yesterday and it flew very well. It has a nice stable climb, a good recovery after bumping into the rafters and a good glide down. That glide is an indication that the 1.36 g/m rubber is a bit too much and next time I will use a 1.2 g/m motor, 0.5 gram motor weight. Flight times were around 2 minutes.

The pictures show a flight shot and a picure of my A-6 model and an original wortel.


Title: Re: A6 rules?
Post by: calgoddard on February 20, 2017, 10:34:37 PM
Assume that an A-6 has truly vertical tip plates.

It is my opinion that under the A-6 rules, the area of these tip plates does not count toward the 30 square inch max wing area (projected).

Clearly the tip plates provide effective dihderal for stability purposes and are not used for generating "lift."

Am I correct?

Olbill - this should be one you can answer. 

Thanks in advance. 


Title: Re: A6 rules?
Post by: Olbill on February 21, 2017, 11:01:36 AM
Only projected area counts in the 30 si maximum. Vertical tip plates wouldn't count. Tip plates tilted outwards would count but only for their effect on projected area.

The theory on use of tip plates is that they increase the effective wingspan by helping control tip vortices and other effects that I'm not qualified to comment on. So there should be an increase in L/D if everything is working as expected.


Title: Re: A6 rules?
Post by: calgoddard on February 21, 2017, 01:16:52 PM
Thanks Bill.  Here is a follow-up question.

Can the tip plates be made from 1/64 inch sheet balsa wood and the model still be legal under the current AMA rules for A-6?

Or must they be made of 1/16 inch square balsa wood sticks and covered in either tissue or commercial plastic film?

The A-6 rules do not seem to expressly cover this issue.

I have had very good success with tip plates on my LPP and WS models and on one of my A-6 models.  The latter provoked some consternation by my competitors at our most recent local A-6 contest. Ultimately it survived what in effect was a low level protest. I was allowed to win that contest based on my highest cumulative flight total.  That A6, which may have been a little over weight to begin with, has crept up in weight due to repairs. It is now time for me to build another A-6 as I just barely managed to win that contest. I was told by a mentor long ago something to the effect that "you wouldn't start the Boston Marathon with two bricks in your pockets." It may have been the late, grate Cezar Banks who gave me that sage advice. 

In my experience, I cannot say that tip plates provide any duration advantage over wing tip dihedral sections on indoor models, but they make the wing a lot easier to build. Similarly, in my experience I cannot say that tip plates result in any duration disadvantage. I do like the way they look.   

I will note, however, that I have only ever seen one F1D model with tip plates.  I have not had the fortitude and patience to take on the F1D event, but that is a whole other story.   


Title: Re: A6 rules?
Post by: calgoddard on February 21, 2017, 01:23:47 PM
Here is a picture of my A-6 mentioned in my previous post, namely, Reply #21.

This picture was taken a while ago, but I note I had a hard copy of the A-6 rules sitting next to my model at that time.


Title: Re: A6 rules?
Post by: calgoddard on February 21, 2017, 01:56:21 PM
Here is a link to a video of a trim flight of my A-6 referred to in my last post:

https://www.youtube.com/watch?v=g6sdcA-fYlM&feature=youtu.be

The small circle size is intentional as our contest venue (a different gym from the one in the video) has six foot high beams spaced about 10 feet apart. If you can fly between the beams, and around the lights, you can fly up to about 26 feet.

You can see two problems with my model in the video.  

First, my A-6 is flying too fast, which reflects its excessive weight.

Second, it has a tip stall.

Note that Kang Lee is on the other side of the gym. He was flying one of his F-1D models in the same gym with me that day.


Title: Re: A6 rules?
Post by: jakepF1D on February 21, 2017, 03:01:31 PM
Thanks Bill.  Here is a follow-up question.

Can the tip plates be made from 1/64 inch sheet balsa wood and the model still be legal under the current AMA rules for A-6?

Or must they be made of 1/16 inch square balsa wood sticks and covered in either tissue or commercial plastic film?

The A-6 rules do not seem to expressly cover this issue.

I think the rules are pretty clear on this issue.

"All wing, stabilizer and rudder wood including wing posts shall be 1/16” square wood minimum"

Tip plates are part of the wing, so they need to be 1/16" square.


Title: Re: A6 rules?
Post by: Olbill on February 21, 2017, 03:24:18 PM
Jake is correct. OTOH I think VERTICAL tip plates on the wing and stab SHOULD be allowed to be sheet wood. If a few people agree then I would be willing to put in a rules change proposal to that effect.

This is interesting b/c I had intended to add vertical sheet tip plates to my last A6 wing but screwed up the angle on the tip ribs. Now I'm glad I didn't do it!

(My A6 flies a lot slower than most because of the large stab.)


Title: Re: A6 rules?
Post by: calgoddard on February 21, 2017, 05:13:27 PM
Thanks Jake and Bill.  I am glad I asked about the tip plates on my A-6 that is currently under construction. So I will build them from 1/16 x 1/16 square balsa sticks and cover them with Ultrafilm, like the wing. Bill, I appreciate your offer to put in a rule change proposal relating to tip plates on an A-6 model.  Perhaps it can be dealt with on the next round of A-6 revisions (whenever that might be).  As the intent of the event is to have a simple, easy to construct model, allowing solid tip plates would be consistent with that goal.  


Title: Re: A6 rules?
Post by: dslusarc on February 21, 2017, 06:13:06 PM
I also read the rules to mean 1/16sq for the wing wood as well but also interestingly the rules state that only wood has to be that size. If one were to make winglets from multi layered tissue then they will be literally paper thin. I know on indoor scale models guys use to make turtle decks and parts by laying one layer of tissue on a form then applying white glue and another layer etc. It was rather strong and would hold shape. Kind of like a paper mache. Not sure how heavy that would be though on an A-6. Now playing devils advocate, the rules say ribs have to be 1/32 x 1/16 minimum, consequently one could argue the point that a 1/32" sheet wood tip plate is in actually a specialized wing rib that is used only at the end of the wing or stab.  ;D

Don    


Title: Re: A6 rules?
Post by: calgoddard on February 22, 2017, 10:50:16 AM
Don -

You make several good points, as usual. I appreciate the input from all the experts on the tip plate issue regarding A-6 models. I want to have a good performing model, but I also want it to be legal.

I remember seeing Gary Hodson fly his A-6 over ten minutes at Tustin in 2011. See the attached picture.  The fin on his "Wart" A-6 had an LE that was a curved piece of 1/16 x 1/16 balsa (2 inch radius). It had no balsa wood TE and was "covered" with tissue that was colored like an American flag.  He arranged for an AMA record trial at that venue and his A-6 apparently passed inspection from a structural standpoint.  Unfortunately, Gary was denied a new A-6 record because his model came out a tiny fraction under-weight upon official weighing after the conclusion of the flight. It turned out that this unfortunate misstep did not matter in the end as I recall that Bill Gowen soon set a new A-6 record at the same venue that bettered Gary's 10+ minute flight.

Anyway, I suppose I could make tip plates for the wing just like Gary constructed his fin. Leaving off the balsa TE would save a little weight but, more importantly, might reduce drag. Sometimes the tiniest changes improve the performance of our indoor models ever so slightly. 

Do you think tip plates constructed like Gary Hodson's fin would be legal under the current A-6 rules?


Title: Re: A6 rules?
Post by: Olbill on February 22, 2017, 02:35:00 PM
Definitely they would be legal.

To change the subject a little, last year at Kibbie I saw hands down the nicest version of my design I've run across. It was built by Kurt Schuler (hope I didn't butcher his name)

Kurt hated the square wing and stab ends so made his with curved LE's. My model has the wing and stab LE's turned 45 degrees so they are diamond shaped in cross section. Kurt's did also. I asked him how he did it and I think he said that he laminated the tips from several layers of wood that wound up 1/16" square in the diamond shape. It was an amazing and impeccable piece of work. The whole model was flawless.


Title: Re: A6 rules?
Post by: Flyguy on December 30, 2017, 12:16:06 PM
I never paid attention to A6 because I thought it required paper covering, but now that I see that plastic is allowed, it just seems like a great idea! Easily transportable and the 30 sq in wing limit leaves some room for design fun. I already drew one up and have building underway (there's some flying next week), goes together fast. Great for both beginners and older flyers (because of the bigger balsa sizes).

One comment on the rules - seems like there should be an explicit provision that no VP props or any gadgets are allowed, which would ruin the idea behind the event.

The rules already say that no special materials (boron, carbon fiber, foam) can be used, but maybe it should explicitly say that only balsa can be used for the structure?


Title: Re: A6 rules?
Post by: dslusarc on January 04, 2018, 10:11:54 PM
As of yet no one has built a VP for A6 however if it was to happen it would not last long as the rules would be changed in the next rule cycle so the "victory" would be short lived. As far as specifying balsa, that would invalidate some records and many models as many people use basswood for the prop spar to get flex/flare of the blades. Since A-6 has been adopted as an AMA event I have not seen people looking to push the boundaries of the written rules that would require a rule adjustment. My guess is that any "abuse" would just be corrected in the next rules cycle so people do not bother doing it in the first place. Plus the A-6 event was around for some time before being adopted so I think that plays into the mindset a little. 

Don     


Title: Re: A6 rules?
Post by: Flyguy on January 05, 2018, 06:19:54 AM
Thanks Don, it's good to know that the event will be protected from developments that have taken the fun out of other events! I think we can get several of our flyers to build one which would make for a fun contest.