Atmosphere edge plane

[Abel Military Services]

I want to build a plane that can fly up to 20, 000(even higher), just like the U-2 but kerbalized. I want it to be easy to control, and have a good high altitude performance. I've got an idea that uses NTRs. But the NTR is too long. 

Any ideas? 

[Echo__3]

The Whiplash and RAPIER can both be used at that altitude. 

[Coyote Foxtrot]

I can't imagine that the nuclear engines will be efficient enough still being that deep in the atmosphere. Whiplashes and RAPIERs will still operate at high altitudes and the Panther still can in afterburner mode. If you're going for a U-2 approach, thin but long wings are essential (albeit, the actual shape of the wing won't matter so it could have a long chord). The amount of air pressure decreases so the U-2 uses more wing surface to produce needed lift over flying faster like the SR-71 or A-12 which simply travel faster for more air pressure and lift.

When it comes to maneuverability, it will generally be bad. If relying on control surfaces, have more control surface area farther away from the center of mass to allow for more torque to be produced by them. Thrust vectoring will generally give the same amount of torque for control, though, there is reduction as thrust reduces with less air (unless using a closed cycle engine). This only deals with maneuvering in terms of the direction the craft is pointing.

If you want good maneuvering in terms of changing your direction of travel, you will have to settle with post stall maneuverability with vectoring engines as there is simply not enough air to allow for your wings to produce enough lift to effectively change the direction of travel quickly.

You say that the engine is too long. Is it because you are getting tail strikes on take off? If so, you can either wait till you get enough speed to pitch up to a lesser amount, or you can angle your wings up to introduce an angle of incidence so that even if your plane is level, the wings will already be generating lift with some speed. There is an added benefit that it will decrease body drag as less body lift is generated where a component of it acts against the forward movement of the plane.

Edited February 16, 2023 by Coyote Foxtrot

[magnemoe]

NTR is better than normal rocket engines once you get some kilometers up. But the high speed jet engines as whiplash and rapier, but think SR-71 not U2 and you want to go fast to cram more air into the intakes. You might also want larger wings. 
I like them because the low landing speed. 
One tricks is to tilt the edge of the wing a bit up it give more lift but don't increase the drag from the fuselage. 
I tend to add a set of landing legs at the rear, I retract before takeoff but they still can hep against tail strikes and is very nice then landing. 

[DeadJohn]

The way KSP aero and parts work, focus on speed rather than wing area. Use the Whiplash engine. It has good high altitude performance and becomes more efficient near its top speed.

For a test flight, try these in order from the nose: shock cone intake -> mk1 inline cockpit -> 2x mk1 fuel tank -> whiplash. Then add wings, landing gear, control surfaces as needed. Raise wing angle by 3-5 degrees; the extra drag from wings will be offset by less drag from the plane's body.

For good control, position wings so that total center of lift is behind center of mass. Consider using canards near the nose instead of or in addition to rear elevators.

 

 

 

 

[Abel Military Services]

Yeah I like the Whiplash but everytime when I goes  above 10,000m it won't work. 

RAPIER is a nice idea. I'm gonna test it. But it doesn't generate EC. 

Any other ideas? (Mod supported)

[18Watt]

Whiplash should work to 20,000 M.  I suspect it is not getting enough air.  A screenshot of your plane would help.

 

[jimmymcgoochie]

The U-2’s flights at 20km are equivalent to about 10km on Kerbin; 20km on Kerbin is like 40km on Earth, well above the altitude that any jet-powered aircraft ever made could reach.