Helicopter Aerodynamics

[themaniac]

Here is the situation.
A helicopter was performance tested at full power. The maximum velocity was recorded (accounting for atmospheric conditions).
The helicopter was then modified, adding a FLIR turrent to the nose. The post-mod helicopter was the performance tested.
The result was that the post-modification helicopter had greater performance than the pre-mod.

My question is this, what is the most likely reason for the performance improvement. Any references to past experiences or papers on this topic would be appreciated.

Cheers

"yesterday i couldn't spell engineer, now i is one!"

 

[GregLocock]

1) CG was in a better place leading to a more neutral trim

2) some subtle aerodynamic effect that reduced the Cd

3) Test to test variability - have you done a gauge R&R?



Cheers

Greg Locock

 

[Miper]

themaniac,
1. What is the helicopter?

2. How much did the speed increase?

3. What was removed from the helicopter when the FLIR was added?

4. What are the weight and exposed dimensions of the FLIR?

 

[davidjh]

"Performance" is typically plotted versus some measure of power/thrust. Power/thrust is computed from various engine parameters. This computation requires "characteristics" curves some of which are depenent on the specific engine configuration (ie;p/n's, part mod levels, areas, etc). IF the engine/powerplant installation was changed in any way between the baseline and mod'd testing that might account for it.