ASpilot2be
Qbicle seat warmer
For the Garretts we have the SRL computer that does the magic for us. But we are on speed at 65%. That is when the generators come online. The starters kick off at 60%.
When starting a turbine engine, how do you know its started?
- Thread starter beasly
- Start date
inigo88
Composite-lover
I probably grammatically bungled that original post, but I meant to say 12% N1 -> Condition Low Idle, Prop Forward. On the TBMs is it prop forward before hitting the starter?
Autothrust Blue
Welcome aboard the Washington State Ferries
Yes. Mind you, I wasn't privy to all the details of that propeller system, since I only got about 10 hours in the things.
beasly
Well-Known Member
You are not a jerk and it was not taken that way
ProudPilot
Aeronautics Geek
Everyone is correct, and I'm just adding videos and quick summary:
Jets drive the intake compressors by turbine blades. We need the air to go in one direction, front to back. When it is up to speed, the inertia of the air and pressure forces air to go back, even when it's exploding. If you don't get enough air pressure or speed, the explosion in the combustion stage will force air from back to front, creating a compressor stall. Also, the temps in the turbine section are incredibly high and need special materials to work. If the explosion goes forward we will severely damage the engine. As such, we need to "spool" or spin the engine up so we have enough air coming in the front before we introduce a flame to the combustion and turbine section. To do this we either use an electrical starter (like piston aircraft, in sorts), air compressed from an external source (ground unit, or APU - which itself is started by an electrical starter), or by compressed air into an engine starter that spins a gearshaft to spin either the compressors, or the turbine section. Depends on the engine.
Jets drive the intake compressors by turbine blades. We need the air to go in one direction, front to back. When it is up to speed, the inertia of the air and pressure forces air to go back, even when it's exploding. If you don't get enough air pressure or speed, the explosion in the combustion stage will force air from back to front, creating a compressor stall. Also, the temps in the turbine section are incredibly high and need special materials to work. If the explosion goes forward we will severely damage the engine. As such, we need to "spool" or spin the engine up so we have enough air coming in the front before we introduce a flame to the combustion and turbine section. To do this we either use an electrical starter (like piston aircraft, in sorts), air compressed from an external source (ground unit, or APU - which itself is started by an electrical starter), or by compressed air into an engine starter that spins a gearshaft to spin either the compressors, or the turbine section. Depends on the engine.
dasleben
That's just, like, your opinion, man
GE CF6 start: Packs off, check duct pressure ~30 psi, open the start valve, at 20% N2, introduce fuel. Chugga chugga chugga. Rolls back to a stable idle, red start limit tick on the EGT display goes away. Rinse and repeat. Go fly! Easiest starting engine I've seen; lights off almost instantly. Now, the triple-spool Rolls RB211 is another story, but it's British, so 'nuff said. 
Boris Badenov
Fortis Leader
Hah! Sissy Garretts have SRL. Manly Garretts have "fuel enrich" button. Basically it's a button that squirts more fuel in to the burner. ALL THAT IS MAN.
Boris Badenov
Fortis Leader
Or, in the case of a PT-6...
ProudPilot
Aeronautics Geek
Fair enough, but still continous flow... nice try... nice try...
Are you asking about a turbo-prop at the end of you're question? Those are a different beast, and there are two fundamentally different design philosophies for them: Direct-Drive (Garrett) vs. Free Turbine (Pratt & Whitney PT-6). PT-6s are weird because they're mounted backwards, and are cut in half...
I was. I've spent many hours lying awake thinking about how 1000shp gets reduced enough to spin a propeller a couple (twenty) thousand RPMs, into a 250mph frenzy, without destroying itself....
Mmmmmmm.... TBM.... Tell me that thing flies as well as it looks.
Autothrust Blue
Welcome aboard the Washington State Ferries
Sweet R-2600 radial there, all 14 cylinders purring along, firing just right.
Autothrust Blue
Welcome aboard the Washington State Ferries
Haven't flown that TBM (yet, if any of them are still flying).
Haven't flown that TBM (yet, if any of them are still flying).
There's one flying at Falcon Field. Privately owned, but donated to the CAF in its off-time.
This. How does it work??? Honestly.
Via gear reduction gearing. In the UH-1H, the N2 power turbine output goes through a reduction gear, where the speed is reduced by 50% to that of the output shaft- the one connected to the transmission. The helo's transmission cant take an input speed of around 20,000 rpms that's being generated, so it gets reduced before that point. For the tail rotor, there are further gearboxes that have reduction ratios to them. N2 about 20,000 RPM, to the short shaft of around 6600 RPM, to the main rotor of 324 RPM.
Autothrust Blue
Welcome aboard the Washington State Ferries
On the ERJ, the ITT gauges display whatever the start limit was only when the engine isn't running - so it's regional pilot proofGE CF6 start: Packs off, check duct pressure ~30 psi, open the start valve, at 20% N2, introduce fuel. Chugga chugga chugga. Rolls back to a stable idle, red start limit tick on the EGT display goes away. Rinse and repeat. Go fly! Easiest starting engine I've seen; lights off almost instantly. Now, the triple-spool Rolls RB211 is another story, but it's British, so 'nuff said.
After start, the arc extends up to normal T/O-1/TO/ALT T/O-1.