MY FIRST DESIGN AT A HOMEBUILT

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Harley

Member
Joined
May 20, 2011
Messages
20
Location
Burlington, WI
Hey Guys,:ban:

First off don't laugh I didn't spend alot of time drawing these up, there more for getting an idea on a page.

The 3 images are different ideas of the same project, and I am looking for your corrective criticism for scale and size of different parts. Of course there are no weight or balance dimensions yet but they will be coming.

I wasn't sure if I am going to be making it out of wood or metal. I am trying to keep weight and size down, I want this to be a small sleek little craft. No wasted space or length.

The width of the aircraft should be no wider then shoulder width (tight fit!)

What sort of engine do you think would be a good choice?

Do you think its possible to make this an ultralight?

Does this design resemble other ultralights or homebuilts or light sport planes?

If you have a similar design please show me!

I think of this as a micro version of a P-40. to give you a visual.

Thanks guys!:ban:
Plane1 001.jpgplane2 001.jpgplane3 001.jpg
 

rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,233
Location
Brisbane, Australia
Hi,
I like the design, even though it is still in the rough and early stage. I'd drop the last design concept, however. You don't want the fuse bottom to step up at the wing trailing edge. Air from the wing is going down, and you'll be forcing air under the fuse at that point to go up. Not good. Separation of air streams will cause significant drag.

Your middle sketches (especially the top one, looks good.

Question: why do you want to sweep the wings forward? Aesthetics? And don't go for the low aspect ratio version. I'd definitely look at increasing the AR for better Lift/Drag ratio, better climb.

Nice work. Keep the sketches coming.

Others may differ in their opinions, of course.

Duncan
 

Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
9,262
Location
CT, USA
Looks more or less OK. Sort of like a Volksplane with tapered wings. Tail might need to be increased. Making an ultralight not easy but not impossible... take a look at the Hummel Ultracruiser and the MiniMax.

-Dana

"The world that we have made as a result of the level of thinking we have done this far creates problems we cannot solve at the same level of thinking at which we created them." -- Albert Einstein
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
1,915
Location
Clatsop, Or
Making an ultralight is not particularly hard. Making an ultralight that doesn't sacrifice a lot to be an ultralight is. This has been covered succinctly and at length here in the past. I second Dana's tail suggestion. Very few pilots complain their tail is too big. More importantly tail arm is helpful in dynamic stability.

Personally, I disagree with the comment about forward sweep-but it's highly construction dependent. Wing divergence can occure with sweep, but more likely to cause problems in a sailplane which can bend quite visably at their tips.

However, I fully agree with the aspect ratio notion. Everything below 6 looks stubby to me, and the numbers back me up.
If you want an ultralight, you'll have to have a minimum of 100ft^2 ~ 9M^2 and there's some regulation to meet. Most ultralights are high wings, but can anyone really say why?

Start looking for a lightweight reliable engine. It's easier to design knowing exactly what's going under the hood.

And so it begines!

Wonderous Mountain
 
L

LongEazyMan

Guest
I like it, it looks like a VP-1 with a VW engine. I do agree with everyone else and what there saying, but cool.




*It's not how you fly the plane, it's how you fly the plane in that situation*

"Leroy" CFI
 

flying2bill

Member
Joined
May 8, 2010
Messages
9
Location
Cedar Rapids Iowa
it's a good start but to go further some things need to be decided, ultralight, experimental, experimental (light sport eligable). A short tail moment makes for twitchy flying, taper wings require more building (more different ribs). Have you tried drawing in cad. You can download a demo version of Deltacad for free, easy to use (speciallee for us non collegiants, seat of the pants injunears). This is what I have been playing around with, mixed elements of 3 different planes
2seat.jpg
 

Harley

Member
Joined
May 20, 2011
Messages
20
Location
Burlington, WI
it's a good start but to go further some things need to be decided, ultralight, experimental, experimental (light sport eligable). A short tail moment makes for twitchy flying, taper wings require more building (more different ribs). Have you tried drawing in cad. You can download a demo version of Deltacad for free, easy to use (speciallee for us non collegiants, seat of the pants injunears). This is what I have been playing around with, mixed elements of 3 different planes
View attachment 12883
Awesome thank you for the updates and tips ! these are the things I am talking about when I need advice. I was hoping to make it an ultralight, but it might be to hard with the weight limit so prob experimental. I will download that demo tonight, also is the CAD program "Rhino" a good software?

Please keep the updates and tips coming and your plane looks great keep the creative juices flowin!
 

D Hillberg

Well-Known Member
Joined
Nov 23, 2010
Messages
1,280
Location
very low low low earth orbit
Never,Never,Never design a cockpit for a "tight fit" 1. in a crash the cockpit may deform and screw you up & 2. The most improtant, Make future plans to get FATTER and
Balder with age.
 

rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,233
Location
Brisbane, Australia
Hi,
For a single seater, go for 24 or possibly 26 inches of shoulder width. A two-seater, 42 inches, or even 44, or 46. The truth is, you will be completely unable to notice the difference of a couple of inches width difference. So go with the more portly. You soon will be...

Duncan
 

Harley

Member
Joined
May 20, 2011
Messages
20
Location
Burlington, WI
Hey Guys,

I really don't get the reasons of keeping a cockpit larger due to getting "Fatter" I think thats a really poor reason. The reason due to crashing is a much better arguement in my opinion. Thanks for the all the info guys!
 
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