Hand propping a turbo fan?

SkyHog

SkyHog

Touchdown! Greaser!
Joined
Feb 23, 2005
Messages
18,431
Location
Castle Rock, CO
Display Name
Display name:
Everything Offends Me
If it were left hot and ready, could one reach in and spin the fan, causing it to kick over?

I’m betting no. But curious...
 
No


Sent from my iPhone using Tapatalk
 
And the other question would be...would you want to be in that location when it does kick over? :)
 
Watching a guy at the local field spin up his MU2 all I can say is those blades are hauling ass before it “turns over”.
 
Turbofan:

LZJ59.jpg
 
Assuming you mean a turbo prop engine. Turbine engines don't kick over, they light off. And they need to be moving a certain minimal amount of air through the turbine before you light them or things get real expensive real quick.
 
Doubt you could spin it to 13%
I’d wager it would ether not work at all, or hit start.
 
SkyHog said:
Turbofan:
Click to expand...

Ok, now that I know we are on the same page, there is no way you can spin it fast enough by hand to light it off. You would need it to spin at about 30%, among other things, and you can't do that by hand.

What triggered the question?
 
SkyHog said:
If it were left hot and ready, could one reach in and spin the fan, causing it to kick over?
Click to expand...

By hand? Not realistically. But this is PoA, since when have we ever been realistic?

Looking in a CJ4 POH I have, the minimum speed for a "windmill" start is 250 KIAS. If you can spin the fan as fast as 250 knots of wind can, and get fuel and ignition introduced at the correct time, then sure, yeah.
 
flyingcheesehead said:
If you can spin the fan as fast as 250 knots of wind can, and get fuel and ignition introduced at the correct time, then sure, yeah.
Click to expand...
Let me eat at one of the local Mexican restaurants and I can take care of both the wind AND the fuel!
Gimme a bic lighter and I have all three covered!
 
I seem to recall an instance where someone got a jet engine running by pointing the exhaust of a running jet engine of another aircraft into the intake.

Might be an OWT, however b
 
Greg Bockelman said:
I seem to recall an instance where someone got a jet engine running by pointing the exhaust of a running jet engine of another aircraft into the intake.

Might be an OWT, however b
Click to expand...

Heard of that happening in the military.
 
Someone needs to learn about multi spool engines, concentric shafts, which spool turns the gearbox and fuel pump, etc.
 
Just to put some numbers to it...you'd need to get the core spinning at 8-10% at an absolute minimum...that's 8-10% of 30,000 RPM or so.

And of course, you can't reach the core, so you'd have to spin the fan fast enough to get enough airflow through the core to spin it that fast.
 
Greg Bockelman said:
I seem to recall an instance where someone got a jet engine running by pointing the exhaust of a running jet engine of another aircraft into the intake.

Might be an OWT, however b
Click to expand...
Chuck Yeager talks about it in one of his books.
 
Greg Bockelman said:
I seem to recall an instance where someone got a jet engine running by pointing the exhaust of a running jet engine of another aircraft into the intake.
Click to expand...

Is that with afterburner or without?
 
Greg Bockelman said:
I seem to recall an instance where someone got a jet engine running by pointing the exhaust of a running jet engine of another aircraft into the intake.

Might be an OWT, however b
Click to expand...
I've heard that they did that quite regularly with the prop blast of the ov-10 broncos to get other broncos started.
 
...and I was worried this was going to be another video!
 
And if the turbo prop in question is a PT6 or similar, the prop isn't actually connected to the turbine shaft. I don't know that you'd get the compressor blades to spin at all by moving the prop to say nothing of being able to get it to 10% N1 for light off.
 
And if it’s a turbine helo, you ain’t “hand propping” nothing but the freewheeling unit. Good excersize for building muscle but does nothing to spin the Ng / N1. ;)
 
Last edited:
OK. I'm thinking this whole "hand prop the turbo" thing could be the next big aviation gag to pull on the "new" guys.
 
Shepherd said:
OK. I'm thinking this whole "hand prop the turbo" thing could be the next big aviation gag to pull on the "new" guys.
Click to expand...
I dunno...many pilots don't seem to notice when a PT-6 prop starts turning the wrong way, even when it changes direction mid-start. o_O
 
You must log in or register to reply here.
Back
Top