Why wont my "jet" work

[johnzigger1]

The jet takes off just fine, but when i try to turn it, it starts yawing and pitching uncontrollably and crashes into the sea A picture of the jet with centers visible

[numerobis]

You don't seem to have any vertical stabilizer, so you'll have trouble controlling slip. Looks to me like for yaw, your center of pressure may well be ahead of center of mass.

For pitch, are those wings set up to control roll? If so, and you're trying to control both roll and pitch at the same time, your controls might not do what you really want.

[drtricky]

I'm not a professional in this area, but I've personally flown a few aircrafts of a similar design; designs that have very small, narrow wings relative to the overall size of the craft (High wing loading). I've noticed that all of them had that same issue too when turning, so I think the wing area of your jet is too small to provide a stable turn.

In addition, your aircraft does not have a vertical stabilizer, which also contributes to its lack of stability in a turn.

Edited March 15, 2016 by drtricky

[Nich]

You reaction wheel might be fighting your control surfaces too

I made a version of your craft and it flew just fine but I cant land it as if you power down the wheelsely battery dies too quickly Are you flying with SAS on?  If you get too far off prograde it will flip quickly

Edited March 15, 2016 by Nich

[FullMetalMachinist]

I'm no expert, so I don't know if I can explain the "why's" very well, so I'll just show you instead.  I took your design and modified it slightly.  The main difference is that I added another fuel tank to give the body some more room to work with, and moved the deluxe winglets up some, and added control surfaces at the back (most notably a vertical stabilizer/control surface). It's very important that each control surface only has one job. So the elevators at the back control pitch, the winglets control roll, and the rudder controls only yaw.  

Also, I'm not sure if you're playing career or not, but I tried a version that uses an Engine Precooler instead of the radial intake. It has less drag but still provides enough intake air, so it's generally better. But if you're in career and don't have it unlocked yet, the radial intake works fine. 

I actually had a lot of fun with this little plane, it's really fun to fly. The only thing is those wheels are really short, so be careful you don't hit the engine when you take off or land.  You had a good start with the design, just needed a little tweaking.  

Here's the craft file if you want to look more closely at what I did.  Hope this helps, and happy flying!

[johnzigger1]

17 hours ago, FullMetalMachinist said:

I'm no expert, so I don't know if I can explain the "why's" very well, so I'll just show you instead.  I took your design and modified it slightly.  The main difference is that I added another fuel tank to give the body some more room to work with, and moved the deluxe winglets up some, and added control surfaces at the back (most notably a vertical stabilizer/control surface). It's very important that each control surface only has one job. So the elevators at the back control pitch, the winglets control roll, and the rudder controls only yaw.  

Also, I'm not sure if you're playing career or not, but I tried a version that uses an Engine Precooler instead of the radial intake. It has less drag but still provides enough intake air, so it's generally better. But if you're in career and don't have it unlocked yet, the radial intake works fine. 

I actually had a lot of fun with this little plane, it's really fun to fly. The only thing is those wheels are really short, so be careful you don't hit the engine when you take off or land.  You had a good start with the design, just needed a little tweaking.  

Here's the craft file if you want to look more closely at what I did.  Hope this helps, and happy flying!

Many thanks. However, I am indeed in career mode, so if you could possibly send me the craft file for the one with the radial intake that would be great

[FullMetalMachinist]

7 hours ago, johnzigger1 said:

Many thanks. However, I am indeed in career mode, so if you could possibly send me the craft file for the one with the radial intake that would be great

I thought I did? Dang, must have uploaded the wrong one, sorry about that. I can upload the correct one in a few hours when I get home from work. 

Or, if you're feeling a bit adventurous, you can download the one I did upload and modify it. You'll have to start a sandbox game, and put my craft file in that save's SPH folder. Then take off the precooler and put on another fuel tank in it's place, and add a radial intake. Then save it and copy it over to the SPH folder for your career game. 

Edit: @Johnzigger here is the correct .craft file. Sorry about the mix up (it also took longer than just a few hours, sorry again).  A couple notes about flying it. Because the back wheels are so close together, it's pretty unstable on the ground, so be extra careful on takeoff/landing.  Also, the roll response is pretty slow, if you want you could use bigger main wings/better control surfaces.  And because the wings are so small it has a high wing loading (craft mass to wing area ratio), which means that it's stall speed is fairly high, around 70-80 m/s.  The few times I was able to successfully land I had to come in pretty steep, and as slow as I could, then do a big flare right at the end to kill my vertical speed (kinda like the Space Shuttle).

Have fun with it, I did!

Edited March 17, 2016 by FullMetalMachinist
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