Flaps on smaller airplanes...

Hi guys,

I'm working on a design for a new small airplane (36" span, approx. 270 squares, .15 - .19) and was wondering if there were any opinions on the use of flaps on these little guys. (Opinions? On this forum?? Nah!)

A quick glance seems to indicate that "serious" small stunters are split about 50/50 flapped to non-flapped. While the primary mission of this plane is to be trunk-transportable in my little car so I can take advantage of "targets (fields) of opportunity" in my area, I do want it to be capable of flying a decent pattern (even if I can't! ).

Any thoughts?

The Akromaster is about the size you are talking about and it does great with out flaps.

Hi Mike,

Put flaps on a G.A Peacemaker (.15 powered). Made little or no difference. Mind you, I can't fly the pattern YET.

Regards Frank.

My 2nd ever C/L model was a Top Flite Jr. Nobler. I used a .19 (way too much motor) but the difference between a flapped built up .15-.19 fuse model vs. a non-flapped profile .35 ship was amazing. I was just a young teen and jammed full up for my loops. The Ringmaster would stall all over the sky but the JN tracked very well.

I've used them on a 1/2a profile. The plane flew the pattern without them but adding them improved the shape of the maneuvers. Read the article Ted Fancher did on his Imitation where he discusses his findings on different size flaps. You can find the article in the members section of the AMA website.

Mike. I'm thinking along the lines of 1/2-A stunt ships. They are so light that the boost from wing flaps doesn't seem necessary.

What do I have? It's a Joe Wagner Scout? (or something like that with a TD 049).

If you want a really slow stunter, it seems that you need to go larger, like 52" wingspan or larger. The smaller ones need to go fast. Remember combat ships have no flaps!

Floyd,
Do you find it way over-powered with the TD?
Mine has a Cub .049B, radial mounted with an external tank. I built it from plans I got from, I think, John Pond. The plans were somewhat incomplete. I got another set of plans from Joe Wagner and found that I had erred on the heavy side for some sheet parts. I plan to build another from Joe's plans one of these days using the correct sizes.
BTW, Joe's plans show rib patterns for both the prototype wing, using 1/4" sq. LE, and the kit version with the formed LE.

George

My own feeling is, if you want to fly it slow, then use flaps. If you want to fly it like a combat ship and keep it light, then who cares? Without flaps you will need to fly faster and build lighter.

But why reinvent the wheel? There are a number of good designs out there already. You building a profile or full fuselage? What size engine are you targeting? What size (length) of lines?

Hey, I am not going to let you get away with asking all the questions.

>My own feeling is, if you want to fly it slow, then use
>flaps. If you want to fly it like a combat ship and keep it
>light, then who cares? Without flaps you will need to fly
>faster and build lighter.

This is what I figured was the case, I just wondered if there was a point at which the difference on a small plane became insignificant. I definately want something that flies more like a stunter than a combat ship. This is just going to be a small airplane that I can put in the car and go fly at the ball field, but I want something that will fly more like a precision aerobatic model than like a moth .

>But why reinvent the wheel? There are a number of good
>designs out there already.

Well, just because I get a lot of enjoyment out of designing and building my own airplanes. I like building from plans and kits as well, but I think its fun to fly something that didn't exist until you "thunk it up"! I probably will end up building a couple of the existing designs too. Are there any that you would particularly reccomend?

>You building a profile or full
>fuselage? What size engine are you targeting? What size
>(length) of lines?

This one is going to be a profile with a .15. Figured it would fly on 52' lines, is that in the ballpark for a .15? (This is my first plane smaller than a .35 except for the inevitable 1/2As, so I'm having to re-adjust my sense of scale!)

Thanks again!

>the primary mission of this plane is to be
>trunk-transportable in my little car so I can take advantage
>of "targets (fields) of opportunity" in my area, I do want
>it to be capable of flying a decent pattern (even if I
>can't! ).

Mike,

If the above factors are the major considerations, and you are not interested in maximum "turn" for flying in competition, I think you are just fine without the flaps. Building your plane straight, reasonably light, and properly trimmed, are probably more important criteria at this stage of the game.

In a conversation about flaps with a past National Champion, he said the "...flaps only add about a 5% improvement in a planes' turning ability...." (paraphrased to the best of my memory...but you get the point).

By all means, look up the "Doctor" construction article by Ted Fancher in Stunt News, May/Jun 1998. (If I were your teacher, that article would be "required reading") <g>. You will learn all you need to know to answer your question.

Have fun.

Cheers,

Mike I got that question 2 years ago and I invested time to develop .15 and .25 size model with foam wing.

You can find details here:

http://www.netax.sk/hexoft/stunt/the_middle.htm

http://www.netax.sk/hexoft/stunt/thetiny.htm

Do not believe you not need flaps. Small model is exactly the same model as large model. If you want fly serious stunt pattern, do not omit them.

The difference of small model compared to large is only in level of line tension and feedback to handle, nothing else. I would say the small model with strong engine keeps “microscopic” but constant line tension over whole hemisphere even at slow speed. My feeling is that the small model has somehow “more space” while flying pattern. It means straight segments are relatively longer between corners.

However, on such small model I recommend following:

- do not try thick or airfoiled stab – you need thin, flat stab and elevator – the best is 4mm thick, carbon reinforced (at least in center) balsa
- do not go to 3” bellcrank – use seriouse 4” bellcrank – it brings signifficantly better properties

I built indentical Flite Streaks, with and without flaps. The flapped ship was smoother, IMO. (Remember, the Streak is a combat trainer, and a very sensitive ship..)

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"When you fall off a horse don't get back on because the horse probably doesn't like you."

I have built a number of small airplanes with and without flaps. They can be made to fly well either way. Light airplane, and reliab;e power, are more important than flaps or not. On 1/2A's a long time ago, for reasons I do not remember, I decided to not have more than 15=20 degrees of flap defelction either way.

A properly balanced Flite Streak, as per the Brodak plans, is a very smooth and stable airplane which will fly a quite respectable pattern.

No quarrel with the Flite Streak, Brodak or otherwise. The last one I built was in 1964, long before Brodak's.

I've seen them with an Fox .36X and 10x6 Top Flight nylon prop, roughly finished, a little tail heavy, and simply WICKED (particularly with a 5" EZ-Just handle). The Streak has a fairly small elevator, it's plenty!

The Top Flight kit was billed as a combat trainer. I suppose that by today's combat standards, it wouldn't qualify.

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"I could see that, if not actually disgruntled, he was far from being gruntled." -P.G. Wodehouse