Restarting engines in flight

[555]

I have been reading throught the manual and I can't find any in flight engine restart procedure. I was experimenting with negative G manuevers and this tends to stop both engines and I have tried restarting them with the JFS starter but this doesn't seem to work. Any ideas on this?

[Tenkom]

If you right click the jfs handle it twists and you can use the second bottle. Then put the throttles to idle and start them normally.

[Rudel_chw]

3 hours ago, 555 said:

I have tried restarting them with the JFS starter but this doesn't seem to work. Any ideas on this?

 

I have not yet really tried to practice this on DCS, but here is a very helpful article that I found on the subject a while ago:

F-15 JFS AIRSTARTS.pdf

[555]

14 hours ago, Rudel_chw said:

 

I have not yet really tried to practice this on DCS, but here is a very helpful article that I found on the subject a while ago:

F-15 JFS AIRSTARTS.pdf 968.35 kB · 8 downloads

This helped a lot thanks - turns out my airspeed was too low. Also using the second bottle worked.

[H60MTI]

I just had a dual engine failure...JFS didn't help at all. JFS kicked on just fine but engines just spooled for about 10 secs then spooled done. 300kts IAS and everywhere from 25,000ft down to 2,000ft. No light off. Big splash...

[Erazor]

 

[tiengo]

Thx Erazor,

 

What is the details procedure ?

I try to understand through the video but I can't reproduce the air-start.

thx

 

tiengo

 

[Ramsay]

2 hours ago, tiengo said:

What is the details procedure ?

TL;DR:

AFAIK the same as a "normal" ground start.

Detail:

For JFS assisted restarts, Engine RPM needs be be below 30% or the shaft pawl (pin) will shear (simulated) and engine fail to start/need repair.
As with a "normal" start, go from engine cut off to idle at the appropriate time/rpm.

Windmill restarting isn't modelled yet.

Edited January 24, 2024 by Ramsay

[Erazor]

5 hours ago, tiengo said:

Thx Erazor,

 

What is the details procedure ?

I try to understand through the video but I can't reproduce the air-start.

thx

 

tiengo

 

Like @Ramsay said, its basically a cold start with the following differences:

• Need to switch to the second JFS bottle by rotating the JFS switch
• In my experience the throttle does not react until both engines are running again (you can observe this in the video)

Edited January 24, 2024 by Erazor

[Rainmaker]

2 hours ago, Erazor said:

Like @Ramsay said, its basically a cold start with the following differences:

• Need to switch to the second JFS bottle by rotating the JFS switch
• In my experience the throttle does not react until both engines are running again (you can observe this in the video)

 

Bottles recharge.  You ‘do not’ need to always use the second bottle. 

[Erazor]

4 hours ago, Rainmaker said:

Bottles recharge.  You ‘do not’ need to always use the second bottle. 

Thanks. Didn't know that.

[Dunska]

I did this by accident after a zoom climb and negative G's flamed out the engines.  I just put throttles to cut-off, hit the JFS (no change of bottle) and then finger lift to start the right engine and throttle to idle once RPM was 24%.  I was able to throttle the right engine up while then starting the left engine the same way.  Luckily I was at 35k feet, so plenty of time to do this.  Got the engines going again and landed.  Was quite fun and unexpected as I was not aware the F-15E engines flamed out like an F-14A