this is the first plane i have built. I have about $65 in it right now
Specs:
Wing span 98"
Length 74"
Weight 15.5 #
25cc gas engine
I am thinking of using a 16x6 prop
I would appreciate any suggestions. I am not looking for it to fly great, just want to see it get off the ground right now.
I will be happy to answer any questions.
Happy Easter.

The engine should be propped for about 7000 rpm. You are going the need more pitch to the prop. Something like a 16-10 should be about right for your Weed Eater 25 .

Keep that plane as light as you can for that is not much engine for that size plane

What would anyone be laughing about, that looks pretty good to me. 8 has the RPMs right for that engine, I would tach it with the 16X8 then work from there to keep it in the RPM/Torque range. My little RCS 22cc tends to over rev with the APC 16X8 and seemed to like the APC 17X6 out of the different props I tried. When that little engine finds a new home I will be trying some of the wooden Xoars on it too. Each engine will like something a little different. Good looking plane, only a non builder would wonder about the way it looks in the bones.

Looks good! I don't (yet) Have any WEEDIES. There has been an outbreak of weed eater motors at our club. Combatpilot in the motor section is largly the cause of it. He does some really nice machine work on 'em. I might even bite that bullet next year.

That looks pretty nice. I take it that is a scratch built plane from your own plans? Have you figured out the CG location yet?
If not, you may want to look at the calculator here... [link=http://www.geistware.com/rcmodeling/cg_super_calc.htm]CG Calculator[/link]
Good luck and keep us up to date on the progress.
Curtis

Now's your chance to jump in and convert some being as you have a resident Garu that can help you through the problems

That's awesome. I really like the tailwheel made from an office chair caster. As W8ye stated, keep it light since that engine is a little small for the size of the aircraft.

Saaaaaaawweeeeeeet!!!

Yes it is scratch built from leftover cabinet material in the shop. We had the engine so we designed the plane around that using a little research from the web. I'm not a member of any club and we dont have any one out here in the sticks that know anything about rc, so we are taking some educated guesses here. We did find a CG formula , but I think the wings ended up a little far back than I wanted. I think it is a little tail heavy. Thanks For the cg Link.

Obechie Obeche does pretty good on model airplanes

Not sure what obechie is.

I spelled it wrong it is Obeche

http://www.google.com/search?hl=en&r...he&btnG=Search

The ARf's have a lot of laser cut poplar plywood anymore

that looks like nice work so far. Once you get it together, you would do very well to contact a club and do the driving to get it checked over and maidened by an experienced pilot. Only about 1% of new pilots can fly an RC trainer successfully the first time, and that's an airplane design that's been refined ever since RC started to be easy to handle. Your plane will be more difficult than those, so I'd hate to see all of that nice work not pay off in at least one successful flight.

Northeast of you at Andersonville is one of the finest hobby shops in the country - Hodges Hobbies

http://www.hodgeshobbies.com/

Model clubs

AIRMASTERS MODEL AIRPLANE CLB

30.48 miles 222 67 FRANK MCCORMICK [email protected]
143 CYPRESS SPRINGS DR
OAKFIELD GA 31707
Phone: 229-535-6171
http://www.geocities.com/clubamac222/

SOUTHERN RADIO CONTROL FLYERS

46.32 miles 3065 40 ALLEN BOURLAND
605 COLLINGSWOOD DR
DOTHAN AL 36301
Phone: 334/793-9727
[email protected]

Looks like very nice workmanship. If this is your 1st attempt on flying though I would say it will probably be a handful with the size of control surfaces. Be sure to check out CG location and get experienced pilot to maiden it. Lots of luck.
You mentioned it being made of scrap material? That could make it pretty heavy if not balsa or liteply.

Yes it is 1/4 " birch plywood fuse. The ribs and tail section is lightweight white pine. I used some basswood on the leading edges. As is it weighs 15# 11 oz. Thats with full 14 Oz. tank of fuel. How much do you think I will add with servos and batteries?

Yes w8ye I have been to Hodges Its a great place. Dont know if I will join the club there though. I will check out the others thanks!

While I appreciate the work that you've put into this plane, I have a very serious doubt about. I'm not trying to stifle your enthusiasm about your project, but I feel this needs to be pointed out because it's very likely going to cause the plane structure to fail. I don't see any of the basic structures of a wing that supports the loads of a wing. By this I mean the spar structure of a wing. Wings are built to support the entire weight of the plane (in fact, when G-forces are factored in the wing is usually designed to support many times the basic weight of the aircraft). Wings are usually built around a "backbone" which is the main load carrying of the wing. This backbone of the wing is usually the spar. The materials that the spar is made from varies depending on the plane and the type of flying, but normally it's made from a stronger material such as hardwood, carbon fiber, or metal tubes. Most times a wing will have an upper and lower spar in which the wing is built on, although depending on the material being used a wing can be built on a single spar. I don't see any structure in this wing that can support of the weight of the wing.

Also missing in the wing are the supports that would prevent shear forces from causing wing failure. Especially on this size of a wing there are going to be forces trying to "flex" or shear the wing. Many planes will use shear webbing between the top and bottom spars in order to prevent these shear forces from causing the wing structure to fail.

If you look at the attached picture from a Top Flite Elder you can the top and bottom spars as well as the shear webbing used to strengthen the wing. The wing of any plane has two basic purposes, create lift and support the weight of the plane. These two roles are accomplished by the basic structures of the wing. The lift is created by the shape of the wings, which is created by the ribs in the wings. Ribs in a wing are not load bearing structures but rather are there to create the shape of the wing in order for lift to be created. The load support in a wing is accomplished by the spar structure in the wing, and as such needs to be strong enough to support many times over the weight of the plane.

With all the work that has been put into this plane I would hate to see that result in failure when the wing folds up on this plane. I would recommend taking the plane as it is in the pictures (not covered) to experienced plane builders and let them examine the structure and see if it's sound and will hold up in flight. I say this because it's possible that we can't see everything that you have put into the structure of a wing, and an experienced builder can see first hand what you have done. Plus, they will be able to determine if the wing will support weight or not.

Ken

I am still a little concerned about that too. The wing has ribs @ every 3 " It also has 3 spars that run the full length of the wing. 2 of which are on the top half of the rib and one that is on the bottom half these 3 spars are spread across the width of the wing. The wings leading edge is wrapped with 1/32 basswood and I have a 1/16 vertical strip that caps off the back of the wing.
I will be adding 2 carbon shafts thru the fuse and into the wing to give it some extra support
Thanks for your concern, let me know if that helps.

How exactly are the wings attached now?

You would need a Carbon fiber or aluminum tube close to the thickness of the wing that will travel at least 1/3 of the way out to the wingtip.

Think of it this way...

You should be able to pick up one wingtip, while a buddy picks up the other and you should be able to vigorously shake the plane up and down without doing any damage. If you can't, the wing will likely fail.

Looking closely at the first picture there seems to be wing braces from below so that might just be fine.
But it I think it would need an experienced pilot for the maiden...

That large aileron dose not seem to be attached to much wood.

It does have aluminum struts that extend out about 1/3 of the wing. The ailerons are attached to a single rib that has been doubled up at the pivot point.
I dont think I will be piloting the first time. I do have a mini super cub trainer and a flight sim program I have been practicing with. I know it wont be the same but atleast I will be used to the controls.

I saw the struts there, but I still do not think that there is enough structure in that wing. There no real spar structure that the wing is built on. As I said, because of G-forces the wing will need to support many times more than just the weight of the plane. I just don't see this wing doing that, even with that strut there. Planes that way much less than this plane weighs have more wing structure than you have here.

my dad owns a j3 piper cub and is awsome do not add any thing extra talk to your hobbie store

Done with the plane! I will be changing the main gear, so dont worry about that. I have done some high speed taxi, but no flight, will be looking for someone to maiden it this week.