Pubhi

My Feedback: (5)

I have been flying off and on for the past few years now and I am by no means a pro at this hobby but I can fly just fine. I have never actually built a kit plane, just ARF's and foamy gliders and electrics but i'm really taken by the idea of building something completely from scratch.

My question is to those who know a thing or two about scratch building. What is the first step, what kind of tools do I need, what kind of skills do I need. I studied mechanical engineering in college but we never really learned anything specific to building flying structures. I have all the scientifc knowlege that may be necessary but I lack any practical experience here. So, please feel free to give me some insight. Thanks in advance.

vicman

My Feedback: (10)

When I build the main tool is a band saw, and sanding block. Otherwise it is like any other repair you have done in the past. Oh yeah you will need a decent space to lay things out in order to glue them togeather, just like when you build from a kit.

When you take your labor of love to the field and it flies better than anything you ever bought... you will also need a bigger hat, cause your head will grow about 3 sizes.

Try it you will like it. I did.

Dr1Driver

Good knives and hand saws. I use Exacto. Change blades often. Good measuring devices. I use a 6", 18", and 36" rulers, all metal. Good alignment devices. Squares, triangles, adjustable protractors, etc. A good work table. I have an old library table topped with a solid core door. I cover that with ceiling tile with the backside up. Then cover that with 3/32" cork. Be sure it's flat and straight. Get your tools from Lowe's, Home Depot, Sears, or the like; not Big Lots or Harbor Freight.

Welcome to the world of scratch building. It's a LOT of fun!

Dr.1

LouW

If you have never built a kit, the jump from ARF to scratch built will be one giant step. I would suggest you build at least one kit before trying a scratch build. That way you can begin to see all the many little details that have to be worked out and the way things go together. After several kits you will have developed the skills as well as the understanding to complete a scratch built project. If you have a good detailed set of plans the scratch build will be a little easier, however if you intend to design and build from scratch without some kit experience it will be a very difficult undertaking.

vicman

My Feedback: (10)

Some day I need to try that kit thing.

R8893

My Feedback: (20)

Building a kit or reviewing plans will also give you a good idea of the size of structural components that have proven over time to be properly sized. As a mechanical engineer you can undoubtedly analyze the structure; I'm trained in chemical engineering so I don't try to numerically analyze models, but I do make logical choices using my experience. I have scratch built (as in designed and built) several models and they met my design objectives. If you don't stray too far from the norm your model will be ok. My limited experience with ARF's (they were presents) was not very reassuring. It looks like some of the ARF manufacturers are very close to the minimum airframe structures. At least at my flying field a whole lot more ARF's shed their wings than do kit built models. (I'm not trying to pick an ARF vs kit fight here, just describing a type of design philosophy)

Jim Thomerson

Actually, when you scratch build, you create your own kit and then build the kit. You would learn a lot from building someone else's kit. I'd suggest at least looking closely at kits or plans of several successful airplanes. One thing I have found very helpful in scratch building one of my own designs is to make a flow sheet. This keeps you from doing something that you have to tear up because it blocks something you should have done first. But also the flow sheet will break the build into a number of small components, and you can mark them off like marking off a shipping list. Gives you a real sense of progress.

Jim

former spad

Scratch building is easier if you get a good set of plans. A few months ago I spent $200 on a scroll saw with a disc sander on the side. Makes wood cutting faster, easier, more accurate. A drill press can help keep holes square. A Dremel tool is handy.
There are several good books on building tips available. If you want to actually design from scratch, "Basics of R/C Model Aircraft Design" from the publishers of Model Airplane News is very good, but complicated as it is filled with engineering formulas that cover just about everything.

former spad

Scratch building is easier if you get a good set of plans. A few months ago I spent $200 on a scroll saw with a disc sander on the side. Makes wood cutting faster, easier, more accurate. A drill press can help keep holes square. A Dremel tool is handy.
There are several good books on building tips available. If you want to actually design from scratch, "Basics of R/C Model Aircraft Design" from the publishers of Model Airplane News is very good, but complicated as it is filled with engineering formulas that cover just about everything.

mmcook

Hi, After you get a set of plans how is the best way to get the ribs, firewalls etc transfered to the wood without destroying them? I tried a copy machine but they came out distorted and that wasn't from the plans shifting in the machine either.

ptulmer

My Feedback: (5)

Carbon paper, or just poking holes through the plans into the wood. Connect the dots and cut.

BMatthews

Hard to find good carbon paper these days. I usually just poke holes through with a pin like pt suggested.

I would suggest you start with something very simple and medium sized and work from someone elses plans for now. You'll have enough to learn without tackling something complex or larger where structural concersn become important. Something for a 25 or so and very simple like a trainer or a funfly profile depending on your flying ability.

It's hard to detail all the steps in erecting a model but if you stop and think ahead often it'll help a lot. A large cieling tile you can push pins into helps alot. And don't be afraid to use lines drawn on the parts and a centerline on the bulding board to assist with lining stuff up. Triangles to ensure vertical components helps a lot too. Packing blocks and wedges can often be used to support parts in alignment or in position while the glue dries to ensure true shapes. Again the drawing triangles can be used to project the centerline up to parts in mid air to ensure they are held in the proper place in space.

Think ahead and never assume anything. If you can do that then you'll avoid banana'itis...

Dr1Driver

The cover doesn't have to be oil tight.

Use a GOOD copier. Try Kinko's or a drafting/copying house. Use the copied plans to guide you, and the originals to make your templates. Alternatively, buy two sets of plans.

Dr.1

ptulmer

My Feedback: (5)

Bruce, don't know what office supply stores you have up there, but carbon paper is available at Staples. It costs more than picture paper though!
Also, if there's a dollar store nearby, poke around for the school supplies and get a three or four pack of triangles for a dollar. When you need to alter one, it's no big loss.

former spad

Transfer the pattern to heavy construction paper/light cardboard, you may have to try 2 or 3 times to get it perfect. Then you can use the pattern to build multiple parts.

mmcook

Hey guys, After reading your ideas instead of tracing to carbon paper I think I will dig out a old light table and see if it works. Then see if I can trace the plans onto some paper and use some of that light glue in a spray can (cant think of the name) to tack the traced cut out plans to the wood to cut it out then use the plans for fit. I have acess to my brothers wood working shop that has just about everything I should need. I have built from 40 sized to 75 sized planes but thay were from kits that were pre-cut or punched out ribs etc. with very little left to do but shape a few pieces and glue together. Thanks for all the help as sometimes all you need is a little push to get the creative juices going.

BWooster

it helps to have a good razor plane. Not a cheap one. Your brother may have a small plane that would serve. If it's properly lapped and sharpened, you should be able to snick a transparent wafer of balsa from any piece of balsa wood, even end grain. I find using a plane is more precise than sanding, and minimizes dust. You only have to sand the final bit.

Also, make cutting and shaping templates from lite-ply from the hardware store (1/8" or 2.5 mm). It's cheap.

Good luck, and have fun.

Edwin

My Feedback: (2)

I use the tracing paper method. 3M 77 spray adhesive is what I use to stick it to the wood. Just a light dusting or it'll be too hard to get the paper off. If I have to do a stack, just spray all the pieces and stick em together. Works ok up to about 4 or 5 layers. Then I cut them out to within 1/16" of the line and finish sand to the line. Just my method, no better or worse than anybody else's.

The tool I use the most is my dremil. Also have a bandsaw, scroll saw, 1" verticle belt sander, drill press, mill and lathe. Tools accumilate over time. Been doing this awhile.
Edwin

dicknadine

I would suggest that you start asking your questions to the fellows at you flying field. there should be a couple of old time builders to help you. assume NOT every one flys ARF's. Kit building is really simple-- follow the instructions. SCRATCH building is a different matter. you have to be an engineer, not only of numbers but how things are done, what is strees and how to overcome it. on and on and on. dick

joetsunami

I think the most important tool you can have is YOU. I've built planes from scratch, using just a few hand tools. Life is much easier with a few power tools to speed up your build, but if you have the patience, even lite-ply can be cut with an Xacto to a tolerable finish.

Comments above about a good set of plans are VERY important also. I've seen plans that came with a Kit that I've later scratch-built a plane from (reason not to be revealed :-) ) where the ribs of the tapered wing are NOT EVEN CLOSE to the right outline. A wing built from them would not even have it's leading and trailing edges match up with the ribs at the proper locations (ribs are tool long or short, too tall or short).

If you are the 'type' to scratch-build, you should make it ok. The 'type' means: you know more glue is not necessarily better, you are aware that a tight joint is INFINITELY better than a loose joint, you strive to insure that the parts are warp-free, you can figure out ways to check the fuse and wing for proper alignment and decalage, you know that the firewall MUST be at the correct angle, you are ready to check and re-check the CG and can easily change the locations of radio and battery to make it correct, and lastly and most importantly, you must ENJOY doing all of this!

Many things to do with scratch building will come with time: better tools, a deeper understanding of the proper size and grade for important pieces of wood in the plane, where to add or remove excess wood, how to know when it's ok to 'fudge' a little, but with a normal build, you will do alright.

Good luck, and enjoy.

dicknadine

Just to reiterate and not start a fuss. True Scratch building is creating your own plans, you are the Stress engineer, the Detailer, the Carpenter, and the Proud owner of your own scratch built airplane. building from a set of plans is Plan building, you transer his lines to the wood. the next step is Kit building with some else's printed wood and all the required matl packaged for you. once you build from one of the above and show up at the field and fly it-- Your chest sure gets big. I suggest you start with a kit and gain experience and advance from there. there I said it again. the amout of tools we use to acheive the result varies so much with everyone that I can't comment, its the end item at the field and in the air. Dick Stamm