Hey Guys
I'm currently building a competition 0-1. I have a practice plane also. Both planes are from vailley plans. Practice plane weighs 27lbs. Power for both is a 3.6 moki twin. Alternate firing so it sounds like a little harley. I'm also laying up out of unidirectional carbon an exact scale landing gear. I'm hoping to have the gear done next week. Then we'll start testing it's ability to take the load. 27 pounds makes for very nice flying combo with the moki. Handles the crosswinds very well. Dead calm competition weather rarely happens, for me anyway.

Paul - Could you provide the dimensions for the landing gear? I would like to make mine closer to scale that what's available.
Thanks!

I'm very interested in how your gear turns out, and how well it "springs" and supports the plane, and how much it weighs. If they work well and to your satisfaction, would you consider making a set (or two) to sell? I don't have any experience in laying up carbon fiber.

Hey guys
Just made the blocks that will shape the gear from the front view. Yesterday I visited a dog thats currently undergoing restoration. I measured the gear. The first lay-ups will be .250 at the fuse attachpoints and about .375 at wheel attach points. The real gear is only about .800 thick everywhere. I'll try these dimensions which should be a lot closer than any other gear available. Of course if these dimensions turn out to be thicker than neccesary I"ll reduce. I can lay several sets once we know they'll work for cost of the uni. I learned a tremendous amount about this airplane by just shooting 100 photos. Which 3-views are you guys using for the vailley kit?

I don't have a set of 3-view drawings, per se. I have several hundred photos at differing angles plus many diagrams and specific measurements, all in Minard Thompson's wonderful source, "The Lovable One-Niner". I also have about a hundred photos and close-up detail shots of two local 'Dogs that have undergone fairly recent restoration. I use proportional calipers to take measurements from the photos and translate to the plans to get the details and scale I need.

I've been in communication with the owner of one of these planes, as soon as we can get a time mutually convenient, I'm going out to take more pictures and detailed measurements, from the prop hub to the rudder light.

You guys have got to get a grip!

To begin with, you may, or may not, be aware of the fact that Paul MacReady designed, built and, had flown successfully, a 90' wingspan aircraft that weighed 60 lbs., minus the pilot...a guy who could pedal lak krazy!!

Secondly, in this age of techology, why, oh why, would you not utilize some of these wonderful materials we have that are so incredibly strong, lightweight, inexpensive and easy to work with?

And lastly, do you know of any, full-scale, aircraft being made with wood and fiberglass? Gee!!!...wonder why.

From that great line in "The Graduate", "...plastics, young man, plastics."

Mylar's tensile strength is 32,000 p.s.i. tensile strength whereas medium grade balsa is around 2890 p.s.i. Doesn't it stand to reason that you're replicating a stressed-skin aircraft (Alclad tensile strength is 28000-34,000 p.s.i.) and, instead, you're building what would easily quailfy as a marine (Boat) structure with the attendant weight penalty?

In aeronautical design, you first establish what you want for a wing and power loading. If you begin by saying it's going to weigh 25 lbs., it will indeed if you have to put a pound of lead in the nose to balance it, Damnit!!! If, on the other hand, your desired weight is 10 lbs., that's what you strive for. There's and upward (lighter) design cycle as well as the downward (heavier) design cycle. An aircraft that's designed to weigh 10 lbs. will need less strength (READ: WEIGHT) for virtually everything! The flying/landing loads are 40% so the weight, if you did it right, can be 40%. IT WILL FLY SLOWER, MORE SCALE LIKE!

Nuff said...learning is a wonderful thing, isn't it?

I can walk the walk, also. Attached are photos of a 36" wingspan P-51A I designed and am in the process of finishing up. Target weight is 16 oz. RTF. Fully aluminum skinned, full, animated pilot moves with controls, detailed full cockpit/radio compartment, functional canopy, (Wheels are for static displaly only.) Aluminum over Mylar wing skinning, aluminum over 1/32" balsa fuse w/built up empennage. Now, about the impossible, 15 lbs. scale detailed 1/4 scale Birddog...hmmm a 1/4 scale pilot with full rudder/stick animated pilot...spotter!? Yeah, and make the pilot's throttle hand move, too!! Yeah!!! COOL!

This is what's possible when you stop accepting what's been done and explore what could be.

Okay, my turn for stupid questions. Since one can use two pieces of, say 1/4", music wire soldered together for this why would you want to try an FRP? The spring coefficient of the music wire's a known and there's no STINKY!!!

I realize one could sell these FRP gear but at what price compared to music wire. (Sorry, I like innovation but why reinvent a wheel with unkown results

Incidentally, straight carbon's a bad idea I've done so and the downside of carbon is it has a terrible elasticity modulus. The first hard landing and you'll have an extra piece with real sharp stickers. If you're really dedicated, I'd recommend you lay it up witht Kevlar on the lower surface. It has a much better tensile modulus and the carbon has a good compression modulus.

Themadmax
I'm sure your ideas are sound and don't doubt that all of what you say can be done. At this moment I'm dealing in the reality that I need this plane done soon so..... Gotta compete this spring with it. No time to re-invent the wheel. Jeff Foley 3 times topgun winner and several times nats winner also nasa wind tunnel model builder is advising me on the gear. Were working to come up with the most scale like and funtional gear possible. Again I need to compete in the next months no time to try what I don't know. I'm just a humble model builder who truly loves the heat of competition. Havent done so well yet but I will.

khodges
sounds like aplan on the photos. I ordered all the 3-views that banka has should be here tomorrow. I'll keep you posted on which most closely matches the vailley design. Going to document the wings 2morrow on our local restoration project. Should have a disc that will contain enough photos to be useful to you. Will be glad to e-mail anyone with what I have. again I should have some preliminary gear next week. I will the start some drop testing . I'll try to prove whether it'll withstand my occasional arrival rather than landing. LOL!

A very interesting thread. I'm about to start building a 1/5th scale Bird Dog from a Marutaka plan (Can't find a kit here in the UK). I'm keen to reduce weight, hopefully below 10lbs, in order to use my Saito 90ts flat twin. Lovely smooth engine with a great sound, but not the most powerful 90 size engine at only 1.2bhp. Marutaka used a lot of fairly heavy ply, and much of this could be replaced by balsa or laminated ply balsa or balsa/gf. Lighter models need less power and fly more slowly so look more scale-like. I take the point too about devitions from scale, and like some of you, feel the alloy plate u/c looks particularly naff. I will follow the moulded u/c idea with interest. I had intended to mould something to scale dimensions from carbon fibre to allow some flexibilty and "spring". Of course, keeping the weight down makes this a bit easier.
David

dauntlessuk-

Since this thread started (and the most recent post up to yours was back in Jan), I have arrived at about the 1/3 point in my construction of the Vaillancourt 1/4 scale 'Dawg. I have a build thread in the Warbirds and Warplanes forum, check it out. (25% Cessna L-19/0-1 BirdDog build) There are several builders contributing and some great info. Although I haven't done anything in a month and a half, I am at the point where all structures (fuse, tail, wings, and control surfaces) are built and skinned and initial fitting has been done, servos mounted and controls routed. Engine (G-45 Zenoah) is mounted and many details have been roughed in. I haven't started the interior details yet, but all electronics have a "home" in the fuse.

Some of the scale deviations have been addressed. All the wing control linkages are concealed, but I can achieve the full 60 degree flap deflection of the fullscale, whereas the plans only allow for 45. The inner end of the flaps is correct to the full scale, which required alteration of a couple of fuse formers which also made the fuselage true to the fullscale's. The one scale deviation I can't correct is the H stab incidence, which is modified "so the model will fly.....period" to put it in Roy Vaillancourt's own words.

Some of the details I have included is all nav lights, including the tail strobe and Mars beacon, operating landing lights, which operate from a micro switch when the flaps begin to deploy.

The one thing I still can't figure out is how to build this plane and achieve a weight anywhere near the one that madmax purports is possible. Sure, I could build it like the Gossamer Albatros and use lighter material with tensile strengths thousands of time greater than balsa, but I want to be able to pick it up without putting my fingers through the skin, and would rather not have to take out a mortgage to afford the materials. Right now, my projected weight is in the 25-27 pound range, which I hear from owners of this model is typical, and the performance at this weight with this engine is very good. I am still looking at alternatives to the aluminum LG, even some spring steel alloy, which could be much thinner than the aluminum, but stronger and only minimally heavier, if at all.

Good luck with your Marutaka build, please feel free to use anything from my thread that is helpful or pertinent to your plans.

Hey Max,

Great thread and corrections pointed out by yourself, i like doing my models similar to how you like to do yours. "Birddog" is on my future list to do but currently looking to get all framed up 1/4 scale Unionville Beaver very soon. I have sent you detailed email on the subject. Waiting to hear back from you.

Cheers,
Sam

Khodges,
I'm glad to see you chose to pursue "true-scaling" your Birddog. It's well worth the effort and it's something you can be quite proud of. The Mylar you refer to as expensive is far from it. In fact, it's less expensive when one considers the time necessary to glue, sand, fill and sand balsa sheeting. It's also substantially lighter and can be bent around things like the leading edge without cracking along the grain. Solid leading edges are fine for running into things but we're building an airplane, not a bumper car. Obviously, it's a labor of love but I still like to make short work of whatever I do. Mylar skinning allows more time for detailing and that's the area that really makes a "scale" model standout from the "sorta-scale" renditions. Your fear of punching your fingers through your wings is unfounded...try putting your finger through a material with 32,000 psi as opposed to 2890 psi and you'll understand the folly of that statement. Also, Mylar can be glued on in panels, per the full scale aircraft, so the panel lines are already there, not just grooves in overly thick filler. (READ: LIGHTER!) If I was you, I'd take a paper punch to all those solid wing ribs. It's possible to trim up to 40% of the weight of your ribs with judiciously punched holes. Try it on a scrap piece of balsa and weigh it...you'll be surprised how little strength you lose for the lightness you gain. I hole all my structural members, (JUST LIKE THE REAL ONES!) and I've yet to have a failure due to the holes. Now, that said, when you crash, all bets are off. If it can survive a crash you built it too heavy which is probably why it crashed in the first place. Airplanes should be designed for flying, not crashing. We're supposed to be competent enough when we get into building scale models that we don't build them with crashworthiness as a priority. Trainers are for crashing. I'm interested in seeing what your realized RTF weight is. Per the LG, solder up some music wire units...this type of gear construction has served modellers well for the past 60 years, at least. The LG can be scale, dimensionally, as well as in function...far better than aluminum and easier than FRP.

Nice Job! I hope I provided some inspiration for your efforts.

Upper/Rear Window alum. and rivet detail photo thought you'd appreciate. The "jog" in the wing root area is quite evident in this photo.

I've got about 15 pics of this area alone, from several angles, and have rivet detail of the entire skin, top to bottom, front to rear. It is different in places from variant to variant, depending on whether it is the "standard" or "heavyweight" airframe. The narrowed rear window is one of the details I immediately addressed when I started building, as it is probably the most glaring departure from the true scale lines.

It may not have shown in any of my pics, but I did lighten the ribs prior to skinning the wings, by the method you describe. I still build for crashworthiness, as my building skills remain better than my flying ones, and I hate repairs, and want to keep my 'Dawg flying as long as possible. There's always the accumulation of hangar rash and transport dings, and edges seem to be what takes the greatest amount of hits. Traditional methods are what I know best, so I'll stick with them for the most part, they've worked well for a long time.