F-15 Eagle, who wants to build and test?

[TEAJR66]

I was playing around in Sketchup the other day and modeled an F-15. It quickly transformed into a DTFB model patterned after the FT-22.

I proofed the plans with a build of the airframe. It went together very well.

I have no opportunity to put electronics in it and test it out. I have not even worked out where everything would go. I did calculate a starting point for the CG. A test glide was ok but I could see I was a little nose heavy (that's a good starting point).

(UPDATE): I did some weighted glide testing this morning in larger space. Better starting place for the CG is 1 3/4" forward of where it is marked on the plans. In a bigger space, with longer glides, the original CG marks are too tail heavy. When the plane balanced on a point 1 3/4" forward of the current CG marks, it had a consistent glide that ended in a smooth, greased in, landing. (END UPDATE)


The plane was designed around Ailerons and Elevator (I hope to play with some mixing of those later). Simple bank and yank.

There are two versions here. A prop in slot that would require a 7" prop or smaller (faster motor because the plane is larger than the FT-22). Or, a pusher that will accept a power pod. I was leaning toward the power pod version as the better equipped because a 9x6 prop will fit pretty easily.

Here are some pics of the Prop-in-Slot version.



If anybody is interested in trying one of these out, I would appreciate it. I would like feedback on the plans as well as the plane. The plans are available below. Three separate PDF's for each of the versions. Each PDF is arranged to fit the parts on one sheet of DTFB. Three sheets required. No plans for power pod included (standard FT Power Pod) with the swappable pusher version. Enjoy

 

[Stape]

Man I'm gonna have to give this a try. Always liked the F-15. I'll let you know when I make some progress!

 

[Timmy P]

Only tip I can give that I learned from the F-22... I may suggest moving the motor forward. Reason being is, With the F-22 and a 2822 size motor (small medium motor) you have to hang a 1300mah battery so far out in the nose to hit the CG right.. well Because that battery hangs so far out in the nose in front of the wings that at slow flight the nose just wants to drop. Its an abrupt stall. A friend of mine put canards on his F-22 and could slow fly perfectly.. So if first test it drops the nose hard in a stall.. motor placement may be key.

 

[TEAJR66]

This one is intended to fly a little faster than the FT-22. Not so much on the high alpha side as smooth fast forward flight. This one is a bit larger than the FT-22. You will also notice that there is almost zero control surface in the prop wash. I think the trick with this one is going to be gross overpowering it and running it hot. But, that is only the theory as I have not tested anything accept the build.

Keep in mind, those CG marks are only a starting point. If someone had the time and skills, they might be able to calculate a more accurate CG before testing.

 

[TEAJR66]

Updated first post with better CG starting point.

 

[jayz 84]

Is there enough room to hold a 1800 4s in the nose?

 

[TEAJR66]

There is plenty of room in there. Large squirrels and small puppies could dance in there. 2" wide and 2 1/2"ish deep at the canopy (interior dimensions).

Tip to tail is 41 1/2". Its a pretty good sized model. I was wanting to put I high pitch, small diameter prop on a strong motor and make it fly like a missile. There is plenty of space to work out the balance.

 

[jayz 84]

Is there enough air flow to efficiently run a small prop on there(5x5). I bought a efx racer motor a few months ago for a pusher project that i desided not to do. So it need a home

 

[TEAJR66]

There would be enough airflow. A 5x5 might be a bit small. It would really depend on the finished weight. But the prop would be in pretty un obstructed air all the way through the airframe. Here are a couple pics that might help.

 

[TEAJR66]

Jayz84,

If you are just looking for something to put that set of electronics in, this might be suitable for that size. It might not be as sporty and sexy as you prefer. But if you tested this one, it would save me one less airframe to proof. Again, this was a plans design that has had the build proofed, but hasn't been flown. Designed to be swappable, but the pod is a tight fit. You could just as easily mount a firewall in it and save the pod hassle.

 

[TEAJR66]

Ok. I built one and it flew. It needs a faster power set up. But it fly's fine. Very stable.

The build was pretty easy and straight forward.

Used Elevons only, they should be bigger. The motor is an NTM 2826 1100kv with a 7x5 prop on a 4S 1300mah battery. It definitely needs a speedier power set up. It has almost no roll to it. For some reason it likes flat and happy. Bank and yank turning was fine but holding aileron only produced a very slow roll that resulted in a lot of altitude loss. Limited vertical and inverted is not possible, yet.

The next iteration will have a speedier power set up and increased control surface area and increased throws. I might make the next one with ailerons and elevator.

 

[Mid7night]

Awesome! This looks like a ton of fun ... I might have to go get some more foamboard....