Is it a 'thing' that Airbus produce helicopter rotor systems that rotate differently?

[Hueymeister]

Do Airbus build different rotor systems dependent on customer? I.e Clockwise for France, Counter-clockwise for Germany? I heard this today, never heard it before...

[albatross]

No...
use the pedals as required to maintain heading in the hover.

[skadi]

Do Airbus build different rotor systems dependent on customer? I.e Clockwise for France, Counter-clockwise for Germany? I heard this today, never heard it before...

No! But some types like H125, H225 ( the french ones ) turning clockwise, others like H135/H145 ( the german ones) turning the other direction.

skadi

[212man]

Do Airbus build different rotor systems dependent on customer? I.e Clockwise for France, Counter-clockwise for Germany? I heard this today, never heard it before...
Well it’s true that AH Germany aircraft rotate the opposite to AH France ones, but nothing to do with customers. Just heritage - AHD was originally MBB, and AHF was originally SA. Both chose different paths that have continued.

You don’t honestly believe that they would design different versions of the same model for customers?

[Hueymeister]

Just wanted to fact check something I'd been told....one never knows these days!

[Two's in]

I thought it was because Coriolis forces provide an additional rotational component to clockwise rotating systems in the northern hemisphere and vice versa. That's why helicopters aren't allowed to cross the equator without some nautical engineering ceremony performed by drunken sailors...perhaps I'm getting confused.

[Hueymeister]

:} very drole mon brave

[Wirbelsturm]

nautical engineering ceremony performed by drunken sailors...perhaps I'm getting confused.

Absolutely true, have to fly northern hemisphere choppers in the southern hemisphere for half their life and vice versa otherwise the MRGB gets tangled up......so I woz told! :}

Frighteningly half those blokes were dressed as women and looked better than some of the Pompi lasses! :eek:

[Phil Kemp]

The SA321 Super Frelon was the exception with a 6 bladed Sikorsky S61 derived Main Rotor system rotating counter-clockwise. Should have done the same thing for the S61, that would be a great lifter!

[Fareastdriver]

Rotors turn a different way for the same reasons that propellers vary their rotation. It all depends where the drive is taken off the engine.

All engines rotate clockwise looking from the front. If one attaches the propeller on to the crankshaft at the front of the engine the propeller will rotate clockwise looking from the front. In the USA the propeller drive is normally taken off the back of the engine where a clutch would be in an automobile so they turn the engine around so the propeller is in front therefore the propeller goes anti clockwise looking from the front.

Helicopter drives to the gearboxes using a similar speed reduction system will cause the rotors to go different ways according to the design of the piston engine. With gas turbines you arrange it so that it goes the same way as before.

An example is the Super Frelon. French designed and built but the only one with an anti clockwise rotation because the rotor system was licence built from Sikorsky.

[ShyTorque]

Good theory, but unfortunately it’s not true that all aero engines rotate in the same direction.

[sycamore]

Just make sure the t/r blades are fitted correctly for the rotation.......

[Peter Fanelli]

Rotors turn a different way for the same reasons that propellers vary their rotation. It all depends where the drive is taken off the engine.

All engines rotate clockwise looking from the front. If one attaches the propeller on to the crankshaft at the front of the engine the propeller will rotate clockwise looking from the front. In the USA the propeller drive is normally taken off the back of the engine where a clutch would be in an automobile so they turn the engine around so the propeller is in front therefore the propeller goes anti clockwise looking from the front.

Helicopter drives to the gearboxes using a similar speed reduction system will cause the rotors to go different ways according to the design of the piston engine. With gas turbines you arrange it so that it goes the same way as before.

An example is the Super Frelon. French designed and built but the only one with an anti clockwise rotation because the rotor system was licence built from Sikorsky.

Absolute drivel

[DOUBLE BOGEY]

It depends on which side of the road you drive on.

[Cornish Jack]

Just make sure the t/r blades are fitted correctly for the rotation.......
Sycamore - did you witness the TH incident as well? Amazing that it took so long to realise it was a possibility!

[ACW599]

All engines rotate clockwise looking from the front.

Really? I seem to recall Stanley Hooker mentioning in his book that Merlin and Griffon crankshafts rotate in different directions. And I'm sure I've hand-swung direct-drive light-aircraft propellers in different directions in my time.

[treadigraph]

I believe the P-38 Lightning had "handed" Allison engines, left hand engine crankshaft rotating clockwise, right hand anti-clockwise. Some Twin Comanches and Navajos had counter-rotating props which I think also used handed engines rather than gears to determine prop rotation.

[sycamore]

CJ, don`t know about TH,thinking about either a WX or S-K that had blades fitted incorrectly......

[Dave B]

I talked to a Sikorsky rep once about why they did not upgrade the S61 with more powerful engines, and composite rotor blades. He said that Sikorsky were quite willing to do it, but they wanted the operators to put up some money first.
No one would.

[sandiego89]

I talked to a Sikorsky rep once about why they did not upgrade the S61 with more powerful engines, and composite rotor blades. He said that Sikorsky were quite willing to do it, but they wanted the operators to put up some money first.
No one would.

That seems to be a common issue. Some operators with heavy maintenance expertise have had success improving upon the original design- and some like Erickson and Viking (Twotter) even buying the license. Seems like the Carson blades do the trick nicely. https://www.carsonhelicopters.com/s-61-crmb

[Apate]

I talked to a Sikorsky rep once about why they did not upgrade the S61 with more powerful engines, and composite rotor blades. He said that Sikorsky were quite willing to do it, but they wanted the operators to put up some money first.
No one would.

Not quite true though. Early 80s the major operators got together to look at an upgrade package: Helikopter Service, BAH, Bristow, Greenlandair ++. Bristow eventually pulled the plug as they'd done a deal to buy 332Ls instead.

[megan]

Confirming the Merlin and Griffon cranks rotated in opposite directions. The de Havilland Hornet had handed Merlins which was achieved by an idler gear in the prop reduction gear casing, done to reduce torque effects.

On the P-38 the engineering was some what different.To make a left hand engine from a right hand engine, you have to reverse the crankshaft, replace a regular gear with an "H" gear (this is a gear that skips over a gear that was used), and add a standard gear to reverse the prop rotation after you skip with the "H" gear. Every Allison engine has the ability to be reversed if you have an "H" gear and the added gear.

The right hand bank as viewed from the distributor end (rear of the engine) must have several spark plug leads interchanged because the cam lobes are backwards. It works out the same for the left-hand bank, somehow ... no left bank changes to the firing order

Basically, to make a left from a right, the engine must be almost disassembled because you must be able to get to the gear case in front and must split the case and disconnect all the rods to reverse the crankshaft.

However, if you are BUILDING a left or right from parts, the difference in build up is trivial, assuming you have an "H" gear, the new gear, and you know the plugs to interchange (this means rewiring the ignition harness on one side ... so it is MUCH easier to simply build a left or right wiring harness than it is to change one that is already wired).

The "H" gear:

A Standard gear is just a gear with a keyed center. An "H" gear looks like two standard gears joined by a small cylinder in the middle to skip over the gear that was formerly meshed by the standard gear. The new gear you add is to turn the skipped gear in the other direction. All gear cases have the ability to turn either way ... the gear bosses are in all of them, internally.

For both left and right engines, the cams turn the same direction and the crankshaft is reversed and turns backwards.

There is no other engine I know of from WWII that as so easy to make turn in either direction when being built up ... two gears, turn the crankshaft around, and change the right bank firing order ... that's it.
You need a starter that turns the other way, and you need an idler type gear to reverse the direction of the cam towers.

The reason for the prop rotation, and they tried all directions and combinations, was to reduce the pitching moment (trim change) power on/off so as to make a steadier gun platform.
https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/1304x1678/p_38001_b2f60e108c045e4bfb06cf187f1227d06d6e1511.jpg

[nonsense]

All engines rotate clockwise looking from the front.

How do you decide which end of the engine is the "front"? By checking the direction of rotation?

[Cornish Jack]

Sycamore - TH late 60s, Whirlwind (10, of course), discovered when rotor start went nasty. Quick shut down and, thereafter, pre-flt check that lower t/r blade matched tail pylon aerodynamics. Memory says George Kelson 'made the discovery', but memory frequently false nowadays!

[Two's in]

Not forgetting the Airbus A400 Atlas has "handed" props that rotate in different directions on each wing to minimize torque effect. Airbus realized that "handed" engines would be a problem from a logistics viewpoint, so one engine on each side has a reversing gearbox between the engine and the prop to produce a clockwise and counter-clockwise prop on each wing. All very clever.

[Saint Jack]

A very wise and long-time Bell employee once told me that main rotor blades advance "ideologically", Soviet helicopters on the left, American helicopters on the right and Europeans can't make their minds up.

[ShyTorque]

Sycamore - TH late 60s, Whirlwind (10, of course), discovered when rotor start went nasty. Quick shut down and, thereafter, pre-flt check that lower t/r blade matched tail pylon aerodynamics. Memory says George Kelson 'made the discovery', but memory frequently false nowadays!

George Kelson.....that’s a name from the distant past.....wonder where he is now?

[Cornish Jack]

Shy - Oddly, taking a lunchtime stroll in Crawley during my Virgin days, a bloke passing me sparked an instant GK recognition flash, but , by the time it had properly registered, he had disappeared. ... just realised, that was nearly 20 years ago!!:sad:

[SplineDrive]

A very wise and long-time Bell employee once told me that main rotor blades advance "ideologically", Soviet helicopters on the left, American helicopters on the right and Europeans can't make their minds up.

This is the clearest explanation and the one I learned. ☺️

[tigerfish]

212, You were very nearly correct regarding the AH (Previously Eurocopter) brand of Helicopters. Eurocopter was born out of an amalgamation of the German Manufacturer Messershmit Bolkow Blohm and the French Company Aerospatial. So AS not SA. Otherwise quite correct.

The EC (Now H) 135 was initially a derivative of the Military MB 105, the 108, later to become the EC135 Aimed at the Para Military market. Built in Donauworth Germany.

Aerospatial also built Military Aircraft, but tended to specialise in Civilian Helicopters like the AS350 and AS355. Mainly built in Marignan France.

TF

[Variable Load]

212, You were very nearly correct regarding the AH (Previously Eurocopter) brand of Helicopters. Eurocopter was born out of an amalgamation of the German Manufacturer Messershmit Bolkow Blohm and the French Company Aerospatial. So AS not SA. Otherwise quite correct.

The EC (Now H) 135 was initially a derivative of the Military MB 105, the 108, later to become the EC135 Aimed at the Para Military market. Built in Donauworth Germany.

Aerospatial also built Military Aircraft, but tended to specialise in Civilian Helicopters like the AS350 and AS355. Mainly built in Marignan France.

TF

212 is also correct, the French division of AH has it's roots in Sud-Aviation which became Aerospatiale in 1970.

[tigerfish]

Thanks VL Had forgotten that. I worked for EC 1999 -2011.

TF

[212man]

212 is also correct, the French division of AH has it's roots in Sud-Aviation which became Aerospatiale in 1970.
Hence it’s an SA330J But an AS332L

[MightyGem]

and the French Company Aerospatial
Which came from the amalgamation of Sud Aviation, Nord Aviation and Société d'études et de réalisation d'engins balistiques (SÉREB) in 1970.

Pumas and Gazelles before 1970 would have had the prefix SA.

[ericferret]

Which came from the amalgamation of Sud Aviation, Nord Aviation and Société d'études et de réalisation d'engins balistiques (SÉREB) in 1970.

Pumas and Gazelles before 1970 would have had the prefix SA.

Sud Aviation of course came from the amalgamation of Sud Est and Sud Ouest hence the early Alouettes are SE3130 and the Djinn SO 1221.

[Training Risky]

I always thought of it as French: clockwise (AS350 Squirrel), US: anti-clockwise (Bell-412EP and Chinook (Front main rotor head)).