I'm building this plane and i have never had a plane with flaps and i'm trying to decide if i should go ahead with the flaps or not.It's 52' w/s powered with a fox 35.looking for suggestions and opinions.Some pictures of the build.Still fitting and building.
http://pic100.picturetrail.com/VOL65.../383753473.jpg

http://pic100.picturetrail.com/VOL65.../383753470.jpg

http://pic100.picturetrail.com/VOL65.../383753466.jpg

You might make the flaps movable, but lock them in place. Fly the airplane and see how it goes, then hook up the flaps and see what the difference is. This will teach you a lot more than just building it with or without flaps.

Thanks for that thought.

Remember that flaps move in the opposite direction to the elevator.
Bob

Jay I like that

High aspect ratio and long elevator moment arm.
Appears to be light.

Looks a little short on area so I would go with the flaps and maybe do as Jim said.

If it was me I would double the spars(1/4) in center section to the 2nd rib out on each side and vertical grain shear web(1/16 or 3/32 balsa) out to the 5th or 6th rib each side.
OR cap the spars with thin x spar width carbon fiber.

High aspect ratio and long tail moments can turn really sharp and fast and break wings in 1/2 doing it.
My 56in span high aspect ratio combat design from the 70s had 6 spars 4 of them spruce and still showed signs of failure, they did last until contest andwell you know how that goes.

is this your own design or????

David

I do plan on beefing up the center section of the wing, the main spars are basswood. I have a dumb question, you speak of a high aspect ratio. Can you explain this to me?And Yes it is my design.
Jim

Aspect Ratio (AR) is span/mean cord. Most stunt airplanes have an AR in the neighborhood of 5 to 5.5. So an AR larger than that is considered high. On the other hand that would be low for sailplanes which usually have much higher AR's (20, maybe?). There are other definitions of AR which are algebraic manipulations of what I wrote.

Jim, when you think of a wing, you usually think of a rectangle shape where the span is greater than the chord. In most cases this is true. the ratio is the difference between the span and the chord. A low aspect ratio wing will still have a longer span that the chord but the differece is not as great To be honest I could not tell you where the cut off point where the high aspect ratio ends and the low aspect ratio starts.

in street talk a high aspect ratio wing, sometimes only referred to as a high aspect wing is one that is relatively long span with a short chord. You might call it long and slender.
A low aspect wing is shorter in span with a wider chord. You might call it a stubby wing
The there are extremes where you would say a very high or very low aspect ratio.
A very high aspect would be likw a sailplane.
A very low aspect wing would be one that for instance the chord was as great or greater than span!
Without pictures it is a little hard to understand so I am providing a link that explains in more technical detail.
http://en.wikipedia.org/wiki/Aspect_ratio_(wing) This link will provide some pictures that will help you to understand.

In the first picture below the red plane is a high aspect wing compared to the other plane. In the second picture below shows what would be a very low aspect ratio wing.
I hope this helps some, LT

Got it.

Jayseas, I really like your prototype. I have a personal design that grew from the sig Banshe/Twister. As for the size of the flaps, I would cut your solid stock 2 rib bays from the tip. 2 Benifits, the tip would be hooking everything, for what the last 6inches does it isn't worth it. Also the hindge line disrupts the airflow, it's nice to keep the outside 6' flying as smooth as possible.
Please take this as a possitive suggestion, it is your design. And it looks great.
-Snuts-

jayseas

Scan and post the plans to your interesting design!
(seriouslyI collect plans)

What snuts said. This will help keep the tips from stalling as well and that is a good thing.

David

One thing that nobody's mentioned in this yet, and this is coming from a VERY LONG TIME C/L flier and RC Glider pilot - - you might want to web in the first 3-4 spaces outside (right side) the fuselage to help in the strength dept. Your design is definitely going to be a good flier, I have no doubt about that at all - but it's possible (probable) that maneuvers are going to put a huge stress on that outside wing. Wouldn't take much more than 1/16 sheeting (placed grain-VERTICAL) between the ribs.

Another approach would be carbon strips epoxied to both spars (outside surface) to help with the strength dept instead of the webbing, but that's a bit more expensive.

Personally, I don't think flaps on this bird would be all that much more effective than just a plain wing - that high AR will definitely rotate in a maneuver - - oh BOY, will it rotate!!!! I'm a long-time fan of the old Sterling Skylark, have built them stock, twin-engine, and with 50% extra wing (definitely a high AR wing with that type of set-up) and the biggest thing I found with that 50% extra was that you MUST fly it all the way to the ground when landing - she floats like a glider, doesn't want to set down until she's nearly at a walking speed.

Definitely interested in hearing how she flies. Good luck!!

Dave

SNUTS,
Can you elaberate on this? (I would cut your solid stock 2 rib bays from the tip) not quite sure what you mean.
Jim

What he means is to make your flaps so they stop about 6" (~two rib bays) from the tips instead of having full span flaps. The idea behind this is that the unflapped 6" of tips flies at a much smaller angle of attack when the flaps are being used so it's far less likely for the tips to stall. Too much flap movement is bad because after about 20 degrees they don't give much more lift and they start acting like speed brakes just where you don't want the model to lose air speed (like a square corner).

IMHO adding flaps and the complications involved like adding strength plus trimming is not worth the effort. You already have what appears to be a light structure which will produce a light model so the extra lift for maneuvers is not needed.

Your choice.

George

Hey guy's, appreciate all the tips and thoughts, i have taken your thoughts and i'm useing them to finish up this bird.Elected not go with flaps, will secure them so if i wanted to try it with flaps in the future it won't be a big deal.I will post back when she looks more complete.Oh another question, do ya think i need .018 lines for this? At the moment i don't have away to weigh her.
Thanks Jim

Take the plane to the post office to weigh it.

.015" lines will be more than adequate for your model. This is all I've ever used with .60 powered comp stunters seeing I fly under FAI rules and we were never encumbered with line sizes.

If you are going to try different line lengths and diameters you might consider adding adjustable tip weight and adjustable leadouts.

George

Ditto George's post.

AMA(just for range we are working in)
under 4lb=.015
over 4lb=.018

If you hit 4lb with that airplane then it will have 2lbs or so of paint on it!

Well i have an update not quite done have had other more pressing things to get done.But here are a few pictures on how its coming.











Jim

Very nice job!! If it flys like it looks you have a real winner!

Ok guys, plane is ready fox 35 installed, tried some ground test runs, and i have a problem,After about 1 1/2 minutes she stops running, did this every time i tried her, but she will fire right back up by just hooking glow clip and a flip of the prop, runs for about a 1 1/2 minutes and stops again.Is it foaming problems or something like that.I really want to take her out this weekend.[:-]

How much run time does your Fox 35 have? Maybe it is heating up and stopping. I presume you are holding the outside wing straight down while running your engine.

When i think of it i really don't know how much run time is on it.Plane was tied down and just sitting on the ground.Setup is no pressure unflow tank.

Question, what causes it to stop from heat? HOW WOULD I KNOW IF THIS IS THE PROBLEM?