txaggie08

i want to start scratch building, but dont know what would be a good plane to start with


i have some p-51 plans, but i think they may be a bit much. what about a cub? any good suggestions?

txaggie08

some other questions in general on lookin at plans

the plans i have here are right to scale on wings. however the fuselage is to short. i have no reference on ho tall or wide this is supposed to be, so for all i know the sucker is right on the money except in length. any thoughts? should i assume EVERYTHING on that sheet is the same out of scale on all dimensions? does someone have a 101" wingspan mustang that would help me with dimensions?

txaggie08

can someone advise me on theat last wuestion especialy please?

tonyc

My Feedback: (4)

Hope I can help some.
I scratch build everything I fly. Scratch building is not for the faint at hart. But it is fun.

Some basic rules I follow, I start with a well known design that I know is a great flying MODEL airplane. Model airplanes have different dimensions then the real version of that airplane. As an example of what I did, I bought a Goldberg Ultimate kit which is a great flying model, I used the plans from this kit to increased the size and make it 1/4 scale. The result is a great flying Ultimate in 1/4 scale.

I am doing the same thing with a Cap 232, I bought the plans from D&L Design for their 1/4 scale Cap 232 and I increased the size to 1/3 scale and I am in the process of building it now.

the point of this is that I am taking a design that I know will fly well when finished and increasing it in size by just a little.

If I wanted to build a Mustang, which is a very complex airplane to build and fly, I would start out a set of plans in the exact size I needed, Ziroli is a designer that has great flying airplanes, and then I would get at it.

As a first scratch project I would pick something a little easier, Cub, Spacewalker, Taylorcraft, etc. These will build fast and fly great. Same rule, get a set of plans that you know will make a great flying airplane and build it.

A war bird is tough to build from scratch, I am building a Ziroli Stuka, but I am using a short kit from a kit cutter, way to many parts to cut by hand.

Just my thoughts, hope this helps

tonyc

Jim_McIntyre

I echo Tony's sentiments.

I have no idea of your skills but, as a first scratch build, I would treat this as a learning experience and stick to something smaller where you have less invested. OTOH, I do have a Nosen Mustang (102"?) but, I recently moved and may have difficulty relocating the plans (packed away somewhere).

DanSavage

My Feedback: (5)

First, find the scale of the model by using the winspan of the full-size as a gauge. The full-size P-51 had a wingspan of 37' 0" or 444". A model with a wingspan of 101" would make the model 1/4.4-scale (444" / 101" = 4.396).

The full-size fuselage length was 32' 3" or 387". If we divide 387" by 4.4 we get 87.95" or 88". So, in order to be scale, the fuselage should be 88" long. If you want to find out where it's out of scale, get a scale drawing of a side view of the P-51 and start measuring.

Measure the wingspan on the drawing and divide the wingspan of the model (101" ) by this measurement. This will give you a scaling factor. Now, multiply any measurement off the drawing by this factor and you'll know what it should be on the model. If it's different, you can use this factored measurement to make any corrections you desire to the plans, even up to and including re-drawing them.

Dan

txaggie08

what im confused about is weather the part patterns are off scale, or just th basic drawing(and plan) of the fuse. It has all the fuseformers drawn out but i dont know if there off.....

DanSavage

My Feedback: (5)

Welcome to the wonderful world of plans-building. This is why I rarely build from anyone else's plans. They will usually take liberties with the outlines (such as a shortened fuselage) that I do not. Who's plans are these? Have you tried contacting the designer?

All of this stuff is basic scratch-building techniques. It all starts with an accurate drawing. Without this, you're lost. A good 3-view should have cross-sections of the fuselage, wings and tail feathers. If it doesn't find another 3-view. Better than a 3-view (top, side, front) is a 6-view (top, bottom, left side, right side, front & back views)

Finding out whether a particular part of a model is accurate or not can be measured on the drawing.

For example, let's say you want to find out if a bulkhead is too tall or too wide. You go to the drawing and measure the height or width of the bulkhead, multiply the scaling factor, then measure the part on the plans. If it's too tall or too wide, you'll know and by how much. Same for any other part.

Dan

AmishWarlord

My Feedback: (5)

I think starting out on some small 40 size models from RCM or MAN plans would be good.

Here is a really good web page I found on the net on scratch building. This guy has some really good advice and a really well thought out web page.


[link=http://airfieldmodels.com/index.htm]Airfield Models[/link]

txaggie08

well I bought a set of plans that SHOULD be considerably easier to build.

there for a 1/4 scale cub(wich will take the gas motor i have just rebuilt), its all stick built from the looks of it(mostly anyway...), wich will be fine since ive already built a stick built fuselage(seniorita). looking at the plans, this will be a relativly simple one to start with(im not sitting here scratching my head going WTH?????, so im not as worried )he also includes a three view in it thats supposed to be scale... I'm hoping this will be my first scratch build(i have about 6 sets of plans, none of wich i think i could build), and wont take three years and my left leg to complete.

AmishWarlord

My Feedback: (5)

That sounds perfect! What size gas engine are you going to use? Cubs dont need alot of power and a 1/4 cub isn't that big. Friend of mine runs a OS 120 FS in his. That would be in the 25cc range for gas.

txaggie08

25cc homelite actualy. im considering clipping the wing and maybe going to a 32cc for a little more oomph in aerobatic type suff

AmishWarlord

My Feedback: (5)

Clipping the wing is OK but keep that 25cc engine. Just build a lite strong airframe. A lite airframe with a 25cc will fly better than a heavy beefed up airframe and a 32cc.

Pick a plane to build, then pick a motor then build the plane to the motor. Once you get to where you can design your own planes this will be really easy.


lets see I want to build a clipped wing cub. OK now I can pick a size or I can pick a motor.

1 We chose the plane's size. OK I want it to be just IMAA legal, 80". I know that a clipped wing cub has a 17% cord to span ratio. So our 80" span will have a 13.6" cord this gives us a wing area of 1088. For a 1088 high wing flat bottom sport plane we'd need a .75 glow two stroke engine. I'd use the Super Tigre 75.

Or.

2 We chose based on motor. I haven't learned how to do this for gas engines yet so I'll stick with glow. Lets say I pick up a good used OS 46 on ebay for $55. Now we want to use it in a clipped wing cub. For a high wing flat bottom sport plane we see that we have to design a clipped wing cub with a wing span of 57.5" and a cord of 10" 575 wing arrea and a target weight of 5 pounds at a 20oz wing loading.


Don't forget to do some research. On your 1/4 scale clipped wing cub this is easy because it's a popular plane. Sig makes one so we can take a look at their specs to give us an idea of what our scratch built one should be like. See as far a gas motors go they have a range of 9.8cc to 14.7cc. Their maximum two-stroke glow engine is only a .90 The weight is 15 pounds that's a 26.6oz wing loading. That's up in war bird range. I'd try and shoot for a 20oz wing loading That would be a 11.3 pound target weight. After I replace all of that crappy lite-ply Sig uses I think I could achieve it.


Wing Span: 86.0 in (218 cm)
Wing Area: 1300 sq in (8387 cm²)
Length: 67.0 in (170 cm)
Weight: 15.0 lbs (6.8 kg)
Engine: .60 - .90 2 - cycle
(9.8 cc - 14.7 cc 2 - cycle)
.90 - 1.20 4 - cycle
(14.7 cc - 19.7 cc 4 - cycle)

txaggie08

ive been reading a bit, and i think i will stick with the normal wing for my first build, sinc i would like to fly this(with some assistance) before it gets to cold and windy to fly(if its done....). its supposed to be a more docile plane with a regular wing

AmishWarlord

My Feedback: (5)

Yeah, the longer wing slows eveything down. Since your scratch building you could make both wings also. Use the long wing for easy flying and the short wing for fun.