L Edge
Legendary member
While doing experiments of NYGAD stealth models and exhaust nozzles, I noticed one of the stealth exhaust designs represented looks very much like the F-22 setup.
Lacking equipment, the only way I approach problems, is to build and study what happens in the flight and then look for solutions. Can I tell you the %, no, only the cause and how bad it is by gut feeling.
I use Oatmeal containers for they are light, strong and can easily be shaped and taped. Reset battery to same hundredth volt to compare. For this presentation, will evaluate the F-22 config.
1st flight tried round as reference point, all trimmed out, then went from round to rectangular shape exhaust. Used balsa wood superglued on outside so inside did not have any sharp or protruding edges.
Took flight and did notice it was a lot slower at full throttle and now noticed a slight pitch up.
Second flight, I made a circle to rectangular plus the saw tooth pattern(like the F-22) top and bottom.
Took the flight and immediate noticed a pitch down and recovered enough to get it up and flying. Speed was less than before and even after trimming i changed the throttle setting and sure enough the down pitch changed.
Recharged battery, took a second flight where I went I checked it out vertically and sure enough, Houston, there is a problem.
Result is that this exit shape is causing a pitch problem that needs to be resolved.
If you are dealing with a F-22 with this type of exhaust shape, you will deal with a reduction in thrust and causing a nose down pitch problem, it is not a stable environment. Sure you can move your battery back to stabilize it at one setting, but it will make your flight environment a living beast if you make it into the air.
This is the plane I did the testing. Gets even worse with a saw tooth pattern is in the exhaust flow.
Lacking equipment, the only way I approach problems, is to build and study what happens in the flight and then look for solutions. Can I tell you the %, no, only the cause and how bad it is by gut feeling.
I use Oatmeal containers for they are light, strong and can easily be shaped and taped. Reset battery to same hundredth volt to compare. For this presentation, will evaluate the F-22 config.
1st flight tried round as reference point, all trimmed out, then went from round to rectangular shape exhaust. Used balsa wood superglued on outside so inside did not have any sharp or protruding edges.
Took flight and did notice it was a lot slower at full throttle and now noticed a slight pitch up.
Second flight, I made a circle to rectangular plus the saw tooth pattern(like the F-22) top and bottom.
Took the flight and immediate noticed a pitch down and recovered enough to get it up and flying. Speed was less than before and even after trimming i changed the throttle setting and sure enough the down pitch changed.
Recharged battery, took a second flight where I went I checked it out vertically and sure enough, Houston, there is a problem.
Result is that this exit shape is causing a pitch problem that needs to be resolved.
If you are dealing with a F-22 with this type of exhaust shape, you will deal with a reduction in thrust and causing a nose down pitch problem, it is not a stable environment. Sure you can move your battery back to stabilize it at one setting, but it will make your flight environment a living beast if you make it into the air.
This is the plane I did the testing. Gets even worse with a saw tooth pattern is in the exhaust flow.
