bluecruiser

I have built a couple of planes but never flown any of them. I have always been interested in adding that custom touch. So I was thinking that since I have all of the stuff that I need to cut bend and weld aluminum that I might try to build a plane. I might sound kind of half baked ( why mess with something that works as well as balsa). Or I may find that its been done and it does not work well. Anyhow any advise or criticism would be very appreciated.

skypupmut

Rivets loosen bolts slip welds crack !
let U guess how I found out ?
if U build strong enough to resist the problems it is also too heavy to fly
could work for electric power but again weight ????

I love working with al
I am also a home built plane nut

Tall Paul

ALuminum planes are rare, but not unknown. For the wing area they are generally too heavily loaded in the usual model sizes.
As the size gets closer to full-scale, the weight penalty drops.
But a flyable aluminum plane would be so close in size to one that could carry a man, and be way too large for flying as a model, the time and money is better spent on the full-scale.

MAJSteve

My Feedback: (-1)

I've thought of doing that too to make a tubular aluminum frame. I saw several problems:

1. Saddle joint - the 1/4 in tubing would have to be jigged and then each joint cut at the right angle and then relieved to make the saddle.

2. Thin wall aluminum tubing is pretty hard to get in long lengths around here.

3. Have to learn how to weld or braze aluminum quickly and neatly (I don't think I need to learn another trade!)

4. Each joint would have to be fitted, then taken apart and cleaned before welding/brazing to get the oxidation off (am I right on this?)

5. Any kink in the aluminum would seriously weaken the structure, so a hard landing could require a LOT of splices and repairs.


Sooooo - I'm building an 8' wingspan Stearman out of dowels (which I know how to work with). This is a Barron design, so it's almost true scale but with all the gussets etc., it won't look that way .

I am going to make aluminum sheet metal parts to cover the balsa, but that should be relatively easy with thin stock and the balsa backing it up. Might go with fiberglass and score the panel lines after priming to simulate the panels and screws/rivets.

I could see doing one out of aluminum rod stock and donating it to a museum for a MAJOR tax write off.

CoosBayLumber

My Feedback: (1)

There was an article way back in the 1950's in either A.M. or M.A.N. on how the William's Bros. did such a thing. They explained forming and attachment, and what you did not need. One item they mentioned, for model purposes, you do not need a framework back beyond the wing.


Wm.

bluecruiser

I have done a little more research on the idea. Weight is a bit of a problem. Even if i scale the formers down and use less of them, i think that the overall weight will be increased by at least 30%. MAJSteve, in order to get the most strength and nicest weld on each joint it should be as clean as possible. you may even have to rough up the tubing where it is to be welded. As far as kinking the alum on a hard landing I feel that it may be best to use thin walled very small rectangular tubing. If you kink that, it would be on a landing that would destroy a balsa plane. I have come up with a few advantages to building an alum plane.
1. I like to work with aluminum.
2. I have all of the necessary tools. If I don't have something it gives me a good reason to tell my wife why I bought a certain tool.
3. I can weld the servo horns to the plane rather than bolt or glue.
4. It will give people something to talk about.
5. I can weld an alum fuel tank into the wings.
6. If it doesn't ever get off the ground i can hang it in my shop with my balsa models which have old brittle glue anyway.

bluecruiser

Ok. I have decided to build an alum plane. Now I need plans. In order to get enough horse power I have to use a pretty big motor for the size of the plane. in order to make balance less of an issue I think that I will start with a Laker. Can anybody tell me where to look for drawings? Or does anybody know of a good design to try this on?

bluecruiser

By the way. How do I get the William's Bros. article? I'm going to need all of the help I can get in order to avoid having to make a trip to the re cycler.

Tall Paul

I recall that Williams Brothers article.. it's on how to build an aluminum Class B Team Racer.
Lots of metal working tips.. but it's a good 40 years old!
The magazine may have been "Air Trails", "American Hobbies for Young Men", "American Modeler".. or "Model Airplane News".

Tattoo

Because balsa, although lightweight and easily formed, is in my opinion the softest and least durable material on the planet for building airplanes. There is a reason modern airlanes are no longer made from wood (comment made respectfully and my opinion only). After 20 years of thinking balsa was what I was supposed to use for model airplanes, I gave up on it, and have been having a blast ever since. Plastic is now my #1 choice, and more recently I've just started experimenting with very simple aluminum fuselage "rail" structures. My first attempt is cronicled here:
http://www.rcuniverse.com/showthread...99&forumid=235
Yes the plane is very crude, but I have found the aluminum to be much stronger and MUCH lighter than I expected. Before you dismiss a plane such as this as being just downright ugly...which I will admit...it is...I think it may be the forunner to some interesting ideas. Although I haven't had the time to continue yet, my next ideas along these lines are to build the fuselage as a "chassie" very similar to a car, where the aluminum is the structural component...and then fashion a non structural fuselage "shell" very similar to how R/C car bodies are done. Also, I've been using close tolerance holes, and fiber lock nuts and bolts to put them together...I've wrung them out, and have had no problems with the bolts losening or slipping.



]

ngr1

My Feedback: (2)

I recently went through my pile of interesting RC articles and dug up one from Scale RC dated 1992. It featured a high wing plane built by Carlos Rangel, it was constructed entirely from thin sheet aluminum. The article does not provide any real details about the construction other than the fact that common full size techniques were used.

Carlos is on the web at http://www.stolaircraft.com/heliorc.htm, you can see a couple photos of him and his plane

banktoturn

Balsa actually has a very good strength to weight ratio. So does aluminum. The difference is that in order to take advantage of aluminum's good stength to weight ratio, you need to get it into the right shape, which is harder for us to do with our tools. This is why you see aluminum tubing and C-channels used, because they have already been shaped, using methods we don't have available, into useful forms. The other problem with aluminum is that getting really good joints is harder using the methods we have readily available. Balsa, on the other hand, delivers its favorable properties in 'bulk' form, so that it only needs to be cut to shape. Since it is so light, thick pieces of it can be used, so that good glue joints are fairly easy to attain. It is unlikely that most of us could take advantage of the inherent strength to weight advantages of aluminum, because we can't get it in the right shapes.

Modern aircraft that are built in garages are indeed built largely out of wood. Modern aircraft that are built in modern factories are built largely out of aluminum, or other, more exotic, metals.

Plastic, specifically coroplast, is somewhere in between. It has really good properties in terms of strength, weight, and joining methods, but it does not allow us to get exactly the shape we want, as we can with balsa. If you are OK with the shape you get when you bend coroplast around a curve, which is fine for most purposes, then it is a great choice. You probably won't see sailplanes that depend on a really accurate airfoil using coroplast. They will be built using materials and methods that allow much more precision.

banktoturn

Tattoo

Sorry for getting off topic, but I'm am continually amazed at what happens when guys who really love building get ahold of coroplast. As a scratchbuilding medium it's still rather new, and new ways to cut, bend, shape and form it are being thought up every day. Some of the planes on this page
http://www.spadtothebone.com/Showcase.html
are innovative but still pretty basic...but some of them are mind blowing. I will always hold guys who still work with balsa in very high regard, and respect them for being willing to do it (Heck...I did it for 20 years)...but my finances, building time, and flying activities (pushing my abilities and combat) don't get along with balsa very well. I also like designing and scratchbuilding airplanes. My planes are ready to fly the day I start building them...and if they are failures, I only lost a few hours in the shop and a few dollars...something else I could never do when I was building with balsa. It's great because I've learned a lot more about designing and aerodynamics in the last 5 years than the previous 20 years, and of my last 300 or so airplanes, I've only had a handful that didn't fly well.

Tattoo

This is where my mind is beginning to race, because I think we can use simple aluminum stock to come up with fuselages that are not only stronger, but lighter than ply reinforced balsa fuselages. The fuselage in the pic is 43" long, and along with 8 bolts and nuts, the weight of the substructure came out to 10 ounces, so your looking at the barebones fuselage ready to stuff and fly at a pound or so depending on what you use for landing gear. Not needing any further strength, any type of plane you want could be shaped around such a substructure or "chassie"...out of 2mm coroplast or foam or even balsa or a combination of them. Since the engine and landing gear are bolted to the aluminum...a cartwheel, hard landing, or even minor crash won't ruin your day.

bluecruiser

I like what I am seeing. The pic of the high wing alum. plane that Carlos Rangel built is a nice plane. I hope that I am building that well after I get a few under my belt.
So far I have been checking out the availibility of the specific size alum I would like to use. Having good luck so far. I am having bad luck finding plans that I can modify for this application. I want to try about a 34"-36" wing span first.

hack

Have you seen my hybrid, aluminum and plastic HOR. The sphor.

Has two aluminum "L" channels for the real stabs. Super light and strong.

http://momentoffame.com/snapshot.html?id=29791

MikeS

My Feedback: (37)

Been helping the local university aero engineers build entries for rc heavy lift competition. They have an aero engineer mentor who insists they use aluminum. He does not fly small scale, and all the expertise on small models advise these guys to give up on the aluminum. After several years and all failures to even fly, the group last year finally went to a combo or foam and aluminum. After every landing the rivets tore, structure buckled and something had to be replaced. This years it is back to all aluminum. The winners usually use foam and carbon fiber where appropriate. Aluminum is too weak when light enough to fly. Our local team's aluminum plane weighed in emtpy 12 pounds heavier than the foam and fiber plane that won. 12 pounds extra payload would have made our team contenders.

banktoturn

MikeS,

Good example. If they had the facilities to cast, forge & stamp exactly the shapes they need, and then connect them with better techniques than rivets, they might have been able to do better on the weight. Without those luxuries, I think that only a few specific, high-strength components ( tubes for spars, etc. ) make sense in aluminum.

banktoturn