(800) 853-2651
SHOP NOW

OT: Turbine Engine Photos

K

KIP in MX

Member
My weekend in Trindad, West Indies has been removing and installing a Pratt & Whitney Twin-Pac engine in a Bell 412. The power sections are 900 shp ea connected to a combining reduction gearbox dropping turbine rpm from 36,000 to 6600 at the output shaft to the helicopter's planetary transmission where rpm is further reduced to 324 rpm at the main rotor. Although the Twin-Pac has 1800 shp output, the transmission is limited to 1400. Cost for the complete Twin-Pac is close to 1 million US.
a55407.jpg

a55409.jpg

a55413.jpg

a55414.jpg

a55416.jpg
 
At the risk of sounding dumb, What kind of coupling does a setup like that have? I mean does it have some kind of clutch or fluid coupling? It surely isn't direct drive to the rotors....What way does it have to engage the rotor(s) gradually?
 
The T400 Twin Pack is used on the USMC/Navy Hueys, and was used on the J and T model Cobras as well. Not enough power at high density altitude for a Cobra loaded down with ordnance, so they retrofitted the AH-1Ts with GE T700s, the same engines used in the AH-64 Apache. As I recall, they beefed up the transmissions to handle 2000 shaft horsepower as well. The resulting Whiskey model Cobra is a whole 'nother aircraft, and performs nearly as well with one engine out as the T model did on both engines.
 
I'm told there are overriding clutches on each engine, so either engine can be shut down. A Bell rep told me (back in the 80s) that this simple arrangement had never experienced a failure.
 
Yes, same engines as the UH1-N and the two Cobras you mentioned. Also installed in modified Sikorsky S-58s that originally had a radial engine, and another version of the Twin-Pac used as a power unit (ST series). The military T400 version uses PT6T-6 insteaad of the commercial PT6T-3 series.

The AH1-W and UH1-Y are complete upgrades including the GE CT-7 engines and Bell 214 type drivetrain, close to doubling the power of the Pratts and drivetrains of the UH1-N and AH1-T.
 
Each power section has a free turbine (compressor coupled to turbine wheel) to generate the high heat gas that powers a seperate power turbine wheel which drives the combining gearbox. This arrangement is the "fluid clutch". Also, inside the combining gearbox at each power section is a freewheeling unit (Sprage clutch) that disengages a power section power turbine wheel in the event of power section failure. Not common, but unfortunatly, it does happen. With one power section inop, the other can put out 1050 shp for a short period, but will not sustain level flight with a high gross weight.
 
As an HVAC engineer, my projects aren"t supposed to move. But a machine that moves is better, and if it has ordinance hanging from it, that"s the BEST!
 
By the way, one long driveshaft that runs between the power sections connects the combining gearbox to the transmission. It's not installed in the last photo, but you can see the flanges it mounts to in the last two photos.
 
Is that a hydraulic coupling between the turbine and the reduction gear? In your top pic, which bleed air stage is flanged off in yellow?
 
You must log in or register to reply here.
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top