Inverted Flight

[Thomasew]

Hi All,

 

 

Thoroughly enjoying the L-39 .. :thumbup:

 

One thing I did notice, .. is that I can only sustain inverted flight for about 35 secs, .. before the engines flames out :joystick:

 

Is this correct for this version of the L-39?, .. and, if so, .. are the ones that the Aerobatic Teams use, .. modified?, .. or, do they use a different version altogether?

 

 

Thanks .. :)

 

Cheers

Tom

[Agg]

In the manual it says that inverted flight should not be performed for more than 20 seconds, and then not for another 20 seconds after you have reverted back to level flight - to allow the tank to refill.

 

I don't think there's anything special about the L-39s used by aerobatic teams, can't remember seeing any of them inverted for more than 20 seconds...

[Thomasew]

Thanks Agg .. :)

 

Read the Manual, .. now, why didn't I think of that. :music_whistling:

 

Actually, I did read thru it, .. but, not in any depth.

 

.. and I didn't get as far as to read thru the specs/checklists etc..

 

Thanks for pointing it out. :thumbup:

 

 

Cheers

Tom

[WildBillKelsoe]

I guess they have special pumps that take just enough fuel to sustain for the show moves.

[vladd148]

To answer your question, virtually every single aircraft can only fly inverted for a brief period of time before potentially encountering the same issue. It is a fuel pump limitation. In our CT-155 Hawks that we fly, we are not to exceed 30 seconds flying inverted under zero/negative g conditions. Sustained inverted flight is rarely necessary in combat situations anyways - only brief periods of inverted flight are necessary to perform many of the offensive and defensive maneuvers used in air combat.

 

Hope this helps,

 

V

[vladd148]

I guess they have special pumps that take just enough fuel to sustain for the show moves.

 

The aircraft used for the air shows actually have extensive modifications to allow them to fly inverted for longer periods of time.

[bart]

Some jets have double ended booster pumps fitted in the collector tank, others have a negative g trap over the pump to extend the time that they can remain inverted, depending on what a/c it is of course. A/C fuel systems can be quite complicated with flapper valves between tanks of the same group, tank thermistors and capacitors etc, but most are designed so the collector tank (the one with the booster pump in it) shouldnt run dry unless very low on fuel, or in an inverted or negative g condition long enough to interrupt the flow of fuel to the collector tank from the others in the group. This would then cause a problem/flame out.

 

It seems most of our DCS stable have this limited inverted flight time attached to them which is a realistic limitation. However the MiG-21 though seems very (a bit too) sensitive to negative g and flame out conditions sometimes for a fighter...?

Edited October 8, 2015 by bart