Counter-Rotating Props

I was reading Kai Petri's interesting and informative 'FW 190' thread (have you ever noticed that all of Kai's threads seem to be interesting and informative? How does he DO that??) Anyhoo, it got me to thinking, and, like most mavens of WWII aviation, I am aware that the Lockheed P-38 Lightning was a twin-engined fighter that was provided with counter-rotating props - ie the left one rotated Clockwise, and the right one rotated Counter-Clockwise (NOTE: evidently, they made some kind of adjustment to the Lightnings supplied to the British so that the right one rotated Anti-Clockwise instead of Counter-Clockwise - those Brits! They always want it their way! ...but I digress)

I'm not aware of ANY other twin-engined aircraft of the period that was fitted with counter-rotating props - B-25, Mossie, Beaufighter, Ju-88, Bf-110, B-26, PBY, A-20 and I'm sure there are a host of others - none, to my knowledge, were fitted with counter-rotating props - only the P-38. So, assuming that I am correct in my understanding, WHY was the P-38 fitted with counter-rotating props? Did it have to do with the unusual 'twin-boom' planform?

And, as a final adjunct to the original question.......



















..... why are the Brits so pissy?



-whatever

-Lou

 

How about the Do-335? Did that interesting airplane have counter-rotating props?

Are counter rotating props even desirable in a tactor/pusher configuration?

I know so little.

-whatever

-Lou

 

The proper term for what you are asking are "handed" props. Counter rotating props are props on the same engine going in different directions such as on some Griffin powered Spitfires with 6 blades. Three turn counter clockwise and three turn clockwise. Also the aircraft Howard Hughes nearly got killed in was an aircraft with counter rotating props. I can't recall the aircraft name but one set of props messed up while he was flying and he was injured pretty good.

I think the answer is that building different engines that turned the props in different directions to counter act the torque was not deemed worth the extra effort for war production and supply at the front. They thought it better to train the pilot to deal with the torque on take off using the rudder. Sometimes it worked and sometimes it did not. On a twin engined aircraft full of fuel and ammo and bombs, you lose an engine on take off you lose your life.

 

OK - you're probably correct regarding the 'counter-rotating' vs 'handed' nomenclature - I don't really know -

But, when it comes to which direction the engine/prop is rotating, it doesn't seem to me it would really matter WHICH way it was turning if it quit! I mean, you're still stuck with one engine rotating in a given direction - whether you've got right-handed torque or left-handed torque....


...but, I may be wrong.... probably am....

-whatever

-Lou

EDIT: In rereading your response, I think I misunderstood your point - you were speaking of counteracting the torque with both engines turning - I think you just made the comment about losing power as an aside... anyway, why was the Lighting the only plane equipped with 'handed' propellers - I mean, every other twin-engine airplane seemed to do just fine with matching engines - why go to the trouble on the P-38? And if it made a difference, why didn't everyone else follow suit?

 

You will have to wait to TA Gardner to see the post. He will have the answer or make a good one up !

 

The trouble with handed props is that it means different two terminal reduction gears in the same plane, in fact two diferent power eggs in the same plane. All engines are created equal (wow!), only they turn the prop this or another way depending on reduction gear - a prop turns at much lower RPM than the engine. So if in a say B-25 you need to change engines you just pick one from maintenance stocks, in case of a P-38 you have to have right- and left-handed engines in stock, two different sets of gears, etc.

A complication for little benefit, something that is easily corrected by application of some rudder pedal on take off.

 

The Lightning wasn't the only twin-engined aircraft with "handed" engines during the war, but I'm damned if I can remember them at the moment.

 

See - THIS response demonstrates two different things simultaneously

1) How cool this forum is
2) How stupid I am - I thought they were completely different engines, and that one of them just turned the other way

So, they were identical engines on each wing, and the difference was in the reduction gearing, which would make for a lot more commonality amongst the parts bins.

So, I'm gathering two main bits of information from this thread.

1) 'Handed' reduction gears were used on the P-38 (and probably few other aircraft), but the results weren't deemed worth the added complexity.

2) Judging by the lack of response from across the pond, the Brits seem to agree that they truly ARE pissy!

-whatever

-Lou

 

You're right, I'm damned too as I can't think of any other, the P-38 is the only one I heard of

Clearly they're not rising to the bait. If you really want to piss them off call them English, it works at all times.

 

Lou, If I was you I'd watch your back from now on...

...And you too Za for encouraging him!

 

How about the Do-335? Does anyone know what the rotation on it's props were? For those not familiar with the Dornier Do-335, it was a late war design that incorporated twin enginers, but instead of on the wings, one was on the front 'pulling' and the other was on the rear 'pushing' (for the Brits, one of the 'motors' was in the 'boot'!)





-whatever

-Lou

NOTE: Just to keep the pissy-Brits happy, one of my favorite Churchill quotes:

"The Yanks will do the right thing............after they've tried everything else."

 

I see your thought but no I amn't (or ain't). With one short sentence I manage to offend English, Scots, Welsh, Northern Irish, Islanders various. Not so bad considering

 

Well, I don't know.....


.... I keep waiting for our 'Brethren of the Isles' to show up and slap my a$$ down (as I so richly deserve) .... but, darn it all, they just seem to refuse to sink to my level of depravity.....





..... frustrating as hell, it is.

-whatever


-Lou

EDIT: It seems that about all the $ is good for these days is maintaining a minimum level of decorum on the forums!

 

Oh yeah, that would do it.

 

Here is everything you wanted to know about handed props. Scarface you can send me your thank you on the back of a $20 bill.

Contra-rotating Props — Tech Ops Forum | Airliners.net

 

Hey.... this is a free forum.....



.... I wouldn't THINK of billing you $20 for joining in!


...but 'Thanks' just the same!


-whatever

-Lou

EDIT: Actually, the link that TA152 provided is a very interesting technical discussion of the various merits and pitfalls of not only 'handed' props, but 'contra-rotating' props as well. Definitely worth a look (just not worth $20!).

-w/e
-L

 

The front and rear engines are the same rotation, but having one engine fiited in reverse, you will automatically get opposite rotation without the complication of reverse gearing.
Ken