Crossbleed start rpm too low?

[sLYFa]

If always wondered whether the max rpm under crossbleed cranking was too low. In the B, you barely get above 15% while in the A 10% is as fast as the TF30 will spin. OTOH, 18% is supposed to be where you move the throttles from Off to IDLE. Now I never experienced a hot start even in the A so I wonder if this is intended/correct behavior. 

[JupiterJoe]

When stationary on the ground, with no air-source connected, shouldn't it be possible to use bleed air from the idling engine to start its counterpart?  I switch air-source to whichever engine is running, select the engine I want to crank and nothing.  I've tried switching on air-start too and still nothing.   I get the feeling in real life this was possible to do.  After all, it's just a matter of using compressed air to generate sufficient engine rpm, isn't it?  Each engine generates plenty of compressed air, so it just seems logical that it can be used to start the other engine.  Am I wrong?

[sLYFa]

Its not just possible but was standard practice aboart aircraft carriers to start the second engine using bleed air from the running engine. Make sure to move the throttle of the running engine though, IIRC there is a switch that inhibits crossbleed starts when the throttle lever is at the idle stop.

[Airhunter]

There was an AFC for the 14A and B that allowed low RPM X-Bleed starts. Prior to that You have to advance the throttle to 87% RPM.

So yes, either HB did not model said AFC or the physics behind it are simply all wrong and not implemented, even though it was common procedure on the boat. I have used said 87% technique and never gotten close to 18% RPM, however, was able to start successfully. 

 

 

Edited September 28, 2021 by Airhunter

[JupiterJoe]

Thank you gents.  I've got it working, after applying a little throttle from the working engine.  The A seems to require a little more throttle than the B, almost to the point of overwhelming the wheel brakes.  I expect I just need to finesse it a little.  Thanks for the help. 

Edited September 28, 2021 by JupiterJoe

[Whiskey11]

7 hours ago, sLYFa said:

Its not just possible but was standard practice aboart aircraft carriers to start the second engine using bleed air from the running engine. Make sure to move the throttle of the running engine though, IIRC there is a switch that inhibits crossbleed starts when the throttle lever is at the idle stop.

Really?  In the Hornet NATOPS it specifically states that crossbleed starts are restricted unless otherwise authorized by the airboss due to the relatively high throttle positions and potential for FOD/Damage/Death to other aircraft and people on deck.  Haven't looked at the F-14 NATOPS that heavily, TBH.

[sLYFa]

Crossbleed starts were required due to the limited amount of airstart units on deck. Once the first engine was running, the huffer could be used to start another aircraft. Jet blast wasnt an issue since Tomcats were mostly spotted on the edge of the deck for startup. 

[Airhunter]

3 hours ago, Whiskey11 said:

Really?  In the Hornet NATOPS it specifically states that crossbleed starts are restricted unless otherwise authorized by the airboss due to the relatively high throttle positions and potential for FOD/Damage/Death to other aircraft and people on deck.  Haven't looked at the F-14 NATOPS that heavily, TBH.

Yeah but the Hornet has an APU.

[Whiskey11]

5 hours ago, sLYFa said:

Crossbleed starts were required due to the limited amount of airstart units on deck. Once the first engine was running, the huffer could be used to start another aircraft. Jet blast wasnt an issue since Tomcats were mostly spotted on the edge of the deck for startup. 

 

Good to know!  Thanks, now in going to modify my start procedure!

[IronMike]

On 9/28/2021 at 9:28 PM, Whiskey11 said:

Really?  In the Hornet NATOPS it specifically states that crossbleed starts are restricted unless otherwise authorized by the airboss due to the relatively high throttle positions and potential for FOD/Damage/Death to other aircraft and people on deck.  Haven't looked at the F-14 NATOPS that heavily, TBH.

 

For Hornet pilots everything is restricted. For Tomcat guys the cowboy years of yeehaaw and wooohaaw still applied.

JK JK

[Whiskey11]

6 minutes ago, IronMike said:

 

For Hornet pilots everything is restricted. For Tomcat guys the cowboy years of yeehaaw and wooohaaw still applied.

JK JK

 

Thank God too!  Wouldn't want it any other way!

 

TOMCATS!