Deciding on design

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Tamecat

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What I was looking at is the way the engine block runs from F-6 back to F-5. If it was continued all the up to lets say the inlets, there would be some sort of reinforcing beams to strengthen the fuse.
 

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Tamecat

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Oct 23, 2003
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Teaneck New Jersey
I know this isn't enough to go on buy I don't want to risk showing anymore of the plans because of copyrights. The plane is like building a plane within a plane. The outer side is ducting for cooling air. I was going to place the radiators in the duct to cool the engie. the fuel tank would go right over the C of G. The main problem is that everything is in the rear. the thing I like the most is the interlock construction of the plane. It looked like a fun project to build. But as stated before, just a dream plane. I don't know enough to pull something like this off successfully the first time around.

If it could be done, how? What are the problems with this design from what you see? As a model, I'm told it is rock steady and easy to fly. For a full scale, I'm not so sure. And yes, the gear is long on this one.
 

orion

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Well, with a lot of rework and custom work, there is a chance that the airplane could be built however, as I said above, having seen a number of these type of efforts over the past decade or two, it's pretty clear that it would take a lot of effort (not to mention, cash) on your part and on the part of the technical help you would need, in order to make it work.

The two biggest problems are CG and ground clearance. A secondary set of problems deal with the scaling effects of going from a model to a full sized airplane. And finally, you then have to have the whole thing engineered for the aero as well as the structural design. But given the willingness and drive to do this, yes there could be an approach developed to this so that you would end up with a flyable airplane.

One benefit is that in a recip powered airplance you don't need to carry as much fuel as you would need in a jet. As such, the fuel would most likely fit well within the wing.

To better control the CG aspects of the design, the wing would have to be placed a bit further aft on the fuselage (although a weight and balance analysis early in the program would tell you whether you need to do this or just shift a few components), the fuel would have to go in the wing, and the engine would have to be placed somewhere above the allowable CG range.

The propulsion assembly would then include a torsional feedback control system that coupled the engine to the drive shaft. The latter would most likely be a graphite wound unit in order to save weight and deliver a superior amount of stiffness. The shaft would then couple through an aft bearing set to the prop.

The prop would have to be designed specifically for this application so most likely it would be a constant speed prop with a smaller diameter than normal (the smaller the better for clearance) with three to five blades, turning of course at a somewhat higher rpm than normal. The take-off performance would most likely suffer a bit from the smaller diameter however if the the airplane had sufficient excess horsepower, the performance should still be pretty good.

The critical part of a buried engine configuration is of course cooling, especially with an air-cooled engine. If you went to a water cooled configuration though, that might be a bit easier.

Otherwise, in general, the wings would have to be smaller, the tail-volume coefficient would have to be matched for the anticipated CG envelope, and a very careful structural design would have to be a critical part of the program in order to keep the airplane within its performance and control parameters.

In short, quite a bit of work.
 

Tamecat

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Wow, :eek:

You're right!:p: That is a lot of work! But at least it is doable. :gig: I do agree that C/G and Ground clearance would be the ultimate problem for the plane. I don't believe the wing would have to be moved back, then again, I'm not the expert here. :whistle: As for the fuel tank, That would be in the fuse on the C/G and not in the wing. Reason for this is, the fuse has more than enough space in it to accommodate a nice sized tank. :ponder: If I was to actually lose my mind and build this plane, i would make a very large model to see how to construct the plane. (Flying would only give handling characteristics from what a friend told me.) :para:

As I said, this is just a dream plane. not to be taken seriously. :laugh: If any of the planes on the above page was to be built it would be the Sunbird. I am in the process of making the fuse plans for this plane. I will take another picture of it and place it here for you to see. THAT plane has a better chance of being built than any of them. :devious:
 

Tamecat

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Teaneck New Jersey
Now that we see what I am really up too, any comments on drawing plans? the measurements are based on 12" because I'm 72" tall. I'm guessing everything will be scaled by factor of 6. I am basing the design on the KRS homebuilt plans. As for the wing, I was thinking of buying a wing kit from another plane for this project. It may not keep costs down, but it would speed construction. :ban:
 

orion

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Just a quick reply here:

From a quick look at your sketches, your vertical tail area is too large, your aft fuselage may be too short and the angles of taper may be too sharp. You generally do not want to taper a fuselage more than about six to eight degrees, especially when you have sharp corners from the cockpit to the tailcone, otherwise you'll tend to get boundary layer separation. If this happens unsymmetrically, the flight could be quite awful since the airplane will yaw or pitch to the side where the flow isn't separated.

Your tail volume coefficient for the horizontal should be at least .5 or .55 for a single place. More places will require a slightly larger tail volume coefficient although that will be a function of several other variables such as airfoil selection, flap geometry and size and the foreseeable loading variables.

The tail volume coefficient for the vertical tail should be about .035, give aor take a bit.
 

Tamecat

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Teaneck New Jersey
Thanks for the observations. :D The tail isn't short, just that the picture is cut approxamatly in half. I tried to get the whole plane in the picture but it didn't show up well at all. The vertial stab is too large. I am in the process of redesigning it. I think I failed to mention that this is a two seater plane and not a single. :rolleyes: I haven;'t picked out a wing for the plane as of yet but keep watching this post. I'll get to it soon. But thanks for all your input and I hope you keep giving more. We all learn as we try to build our dream planes.
 

Tamecat

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Oct 23, 2003
Messages
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Location
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I now have a wing design and a vertical stab design that I will add to the plane. :lex: Now I have to incorporate them in my drawings then go from there.
 

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