Ratio of fuselage and wing

I am trying to scratch built an A-1 Skyraider from internet plans and sources. I have a lot of information already. I would like the wingspan to be 52 ins., and plan to use a fox 40. Can anyone enlighten me as to what would be a good length for the fuselage, in order to make it a satisfactory stunter? How about the tail wing? Are there any rules of thumb for ratios in stunters?

>I am trying to scratch built an A-1 Skyraider from internet
>plans and sources. I have a lot of information already. I
>would like the wingspan to be 52 ins., and plan to use a fox
>40. Can anyone enlighten me as to what would be a good
>length for the fuselage, in order to make it a satisfactory
>stunter? How about the tail wing? Are there any rules of
>thumb for ratios in stunters?

What is the cord of the wing?

The first step in designing any kind of model airplane is to have a look at a bunch of designs that already exist, especially ones that are close to what you want to achieve. Then you can use the basic dimensions and moments, and change the outlines to make it look like what you want it to look like. If you build to the same size and weight, and keep the moments, airfoils and control surface sizes, it should fly approximately the same as the one you copied, with the same engine and prop.

For instance, if you don't mind a faux Skyraider with a huge tail that will work at top levels of CLPA competition, use one of the current top CLPA stunters as a take-off point. If you want something smaller for a Fox .35, look at a Nobler. if you want a small profile Skyraider, base it on a Flite Streak. If you want a very scale looking one, have a close look at Al Rabe's Bearcats or Sea Furies and copy his techniques.

There was a Skyraider stunt model construction article published in Flying Models magazine back in the 70s. The plan may still be available. Email me privately if you need the article.

Eggy,
That was a very good looking ship! Don Typond from HobbyPoxy was the builder if I'm not mistaken.
Bill <><

Thanks everyone. Eggy I sent you an e-mail.

fernando, a really usefull way to look at tail length is to use the tail volume coefficent. Take the area of the tail times the tail moment WRT to MAC. I know a coeficient should usually be dimensionless, but in this case we need units.

You multiply the tail area times the moment and it gives you a length X area, or a volume. So, if you want a shorter fuse you use a bigger tail, but keep the volume constant.

Look at stunt ships you like. Figure the tail volume, and divide by the wing area. Now,you can scale that wing area up or down and keep the tail volume/wing area the same. You figure the ratio you want for stability and control (which, of course is the hard part!) and then you can pick either a tail moment and compute the required tail area or pick an area and compute the tail moment.

All of this will work good for stuff that doesn't get into wacky world. As the tail area gets bigger, the drag from it goes up. But- the weight of the fuselage to support it may go down. Suppose I wanted a low drag tail. Well if I made it infinitely long it would require an infinitely small tail area with virtually no drag, right?

Well, I'd have an infinite mass fuselage with infinite surface drag. Oops!

What did you say? What the hell is tail volume? What the hell is WRT? DO you think a guy who doesn't know a plane doesn't have a "tail wing" would know what you're talking about? I've only been designing airplanes for near 50 years, and I don't know what your talkiing about!!
Bare

>fernando, a really usefull way to look at tail length is to
>use the tail volume coefficent. Take the area of the tail
>times the tail moment WRT to MAC. I know a coeficient should
> usually be dimensionless, but in this case we need units.
>
>You multiply the tail area times the moment and it gives you
>a length X area, or a volume. So, if you want a shorter
>fuse you use a bigger tail, but keep the volume constant.
>
>Look at stunt ships you like. Figure the tail volume, and
>divide by the wing area. Now,you can scale that wing area up
>or down and keep the tail volume/wing area the same. You
>figure the ratio you want for stability and control (which,
>of course is the hard part!) and then you can pick either a
>tail moment and compute the required tail area or pick an
>area and compute the tail moment.
>
>All of this will work good for stuff that doesn't get into
>wacky world. As the tail area gets bigger, the drag from it
>goes up. But- the weight of the fuselage to support it may
>go down. Suppose I wanted a low drag tail. Well if I made it
>infinitely long it would require an infinitely small tail
>area with virtually no drag, right?
>
>Well, I'd have an infinite mass fuselage with infinite
>surface drag. Oops!