|
Gazelle had a clutch, Wessex, Sea King and Lynx have a selectable freewheel on the No 1 engine input.
|
So in these particular helicopters that have the ability to clutch the rotors in or out and run engines without them turning is this common practice? Can the engines be used in an APU mode while not driving the rotors, is this done ? Incidentally, do any helicopters have separate, dedicated APU’ s ? |
For the 3 I mentioned, a ramp and roller freewheel is incorporated in the drive from the No1 engine and this freewheel can be selected in or out.
The No 1 engine can therefore be started without the rotor to provide electrical and hydraulic power before rotor start - it also means you can refuel with the rotors stopped but with one engine still running. Plenty of larger helicopters have APUs. |
Originally Posted by [email protected]
(Post 10623493)
The No 1 engine can therefore be started without the rotor to provide electrical and hydraulic power before rotor start -.
skadi |
The Puma's accessory drive was invented to power the self-propelled undercarriage. This was a monstrosity that consisted of a tracked bogie with skids either side of the nosewheel. Engage accessory drive, start up No 1 and drive your Puma around the countryside and into cover etc.etc.. They flew it but it didn't retract or work very well so they built a rig consisting of the bogies and nosewheel with a pump for the hydraulics.
It would depart The hanger at Marignane and chatter off in the distance. There would be a GodAlmighty BANG and the staff at the hanger would check the time against a sweep they had held in the office. |
Incidentally, do any helicopters have separate, dedicated APU’ s ? |
BV234 does.
Mil Chinook too? |
S-92 has an APU. The engines use pneumatic starters. |
CH-53 also has an APU...
skadi |
AW169 has an APU "mode" with #1 engine electrically declutching and only running accessory section on MGB and engine generator at idle . Can't remember the logic behind engaging and disengaging with regards to engine starts etc...?
|
Originally Posted by Hughes500
(Post 10623190)
Gazelle ( Sa431/342) has a clutch so always start the engine then engage rotor system
As for the subject being discussed here, the first JetRanger I flew had a bum nicad battery.. You mostly only got one chance at the start, and if the engine had been recently run, the starts were pretty darn exciting. Similarly the 206L3 I currently fly is lead acid, and by the end of two years the starts would also start to get sporty until we would replace the battery. My friend's R66 is very nice... Also lead acid, but the starts are always cool and unexciting... Even if you have to motor a warm engine. I also much prefer the latching starter... You just hit the button, let go, and just control the fuel. No having to keep the button mashed down during the start like on the Bell. ( which is always interesting when teaching someone new to turbines... I mash their finger pretty hard to make sure they don't take their finger off the button during the start ) |
The gazelle has a clutch which allows you to start the blades and stop them whilst the engine is running , but this can not be used as an APU as the generator and alternator do not come on line until the rotor blades are nearly at full speed
Originally Posted by Paul Cantrell
(Post 10625090)
Never flown one so I could be wrong, but I believe Gazelle is not a free ( gas coupled) power turbine. So, without a clutch the starter motor would have to turn the rotor system as you cranked the engine.... ( I assume there is a single turbine that drives the compressor AND the output shaft, but that's just a guess on my part, please correct me if I'm wrong ) As for the subject being discussed here, the first JetRanger I flew had a bum nicad battery.. You mostly only got one chance at the start, and if the engine had been recently run, the starts were pretty darn exciting. Similarly the 206L3 I currently fly is lead acid, and by the end of two years the starts would also start to get sporty until we would replace the battery. My friend's R66 is very nice... Also lead acid, but the starts are always cool and unexciting... Even if you have to motor a warm engine. I also much prefer the latching starter... You just hit the button, let go, and just control the fuel. No having to keep the button mashed down during the start like on the Bell. ( which is always interesting when teaching someone new to turbines... I mash their finger pretty hard to make sure they don't take their finger off the button during the start ) |
| All times are GMT. The time now is 00:15. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.