F-15C can't hold orbit above 30'000

[NoJoy]

As title says the Eagle can't hold speed/altitude for an orbit at 32'000 ft. It bleeds off speed quickly.
If I did something wrong just give me a knock knock...f-15c_cant_hold_orbit_32k.trk

f-15c_cant_hold_orbit_32K.miz

[razo+r]

46 minutes ago, NoJoy said:

As title says the Eagle can't hold speed/altitude for an orbit at 32'000 ft. It bleeds off speed quickly.
If I did something wrong just give me a knock knock...f-15c_cant_hold_orbit_32k.trk

f-15c_cant_hold_orbit_32K.miz 29.41 kB · 2 downloads

Increase the speed. The orbit is set to 260kts (I guess ground speed) which is about 150kts Indicated, wayyy too slow.

Also note that when you increase it's speed, it will be able to hold the altitude but because of the steep bank it's doing and basically fully loaded, it will use it's afterburner to maintain altitude. Consider lightening it's load.

[NoJoy]

Ok the weight is too much. But still, 70% fuel has the same effect, speed will bleed off.

Isn't the speed in the advanced waypoint tab IAS? Which should then be roughly 420ish TAS.

Anyways, the bank angle in the orbit is too much, AI tries to maintain ~45°.

I will do some more testing...

Hear ya, thanks so far

[razo+r]

19 minutes ago, NoJoy said:

Isn't the speed in the advanced waypoint tab IAS? Which should then be roughly 420ish TAS.

I am not sure. I set it to 440kts in the orbit task and then it worked.

 

21 minutes ago, NoJoy said:

Ok the weight is too much. But still, 70% fuel has the same effect, speed will bleed off.

70% but still with 3 fuel tanks?

[Czar66]

26 minutes ago, NoJoy said:

Isn't the speed in the advanced waypoint tab IAS?

No. It is ground speed. Above 15,000ft is better to refer to Mach speed.

Try to set mach of .75 for high orbit. If the AI still sinks, try .79 to .82.

[NoJoy]

Well, GS doesn't make too much sense as it takes wind speed into account. I'd set the mach number but the advanced waypoint task only allows knots.

Here's what I found in the Mission Editor Wiki:

Optional Parameters: All other variables are optional.

...

speed: Speed in meters per second the AI will orbit at. If no speed is defined then the AI will orbit at 1.5 their stall speed.

...

I think the wiki is outdated here as the speed in the speed box is set in knots. Anyways when I reduce the fuel to 50% and remove the drop tanks AI maintains the orbit altitude but with oscillating bank angle between 40% - 60%.

So after all I think it's mainly due to the high bank angle. I will set a race-tack holding in my missions because an Eagle with 50% fuel doesn't have much time on station left.

Oh and I think the speed in the waypoint options is TAS. When I set it to 440 it keeps a solid 260 IAS.

Edited March 28 by NoJoy