prop driven aircraft

[rustychisel]

Just thinking out loud...

Do all prop driven aircraft have the prop going the same way, or do they vary? What happens if they go the wrong way, does the plane fall over?

Single engined?
Pusher prop?
Dual prop - I know the Luftwaffe had at least one prototype with dual props contra-rotating.
Multi engine prop: B17, Lancaster... 2 CW on one wing, 2 CCW on the other wing?

[Nooch]

not that i have any idea, but i'd have to imagine if a prop spun the reverse direction, the blades would have to be reversed as well...

[Bruce K]

They go the opposite way in Australia - just like the sinks and toilets!:rolleyes:

BK

[BumbleBeeDave]

. . . as long as the pitch of the prop blades is appropriate to provide forward thrust. If the plane has reversible pitch props, that's what is used to provide braking on landing by reversing thrust, but I would imagine there's a preferred pitch for forward thrust.

I'm not sure if you would have the two wings going different directions to solve torque problems, but I I know that idea has been used with some helicopters to solve the torque issue and eliminate the requirement for a tail rotor. The Sikorsky X2 does this and replaces the tail rotor with a pusher prop.

Pay no attention to BruceK . . . we are obtaining therapy for him. :rolleyes:

BBD

[dancinkozmo]

Can helicopters fly upside down ?

[oldpotatoe]

Just thinking out loud...

Do all prop driven aircraft have the prop going the same way, or do they vary? What happens if they go the wrong way, does the plane fall over?

Single engined?
Pusher prop?
Dual prop - I know the Luftwaffe had at least one prototype with dual props contra-rotating.
Multi engine prop: B17, Lancaster... 2 CW on one wing, 2 CCW on the other wing?

Depends on the design of the prop, which is just an airfoil, that rotates. It is designed to rotate, provide 'lift' which is thrust. If the prop is somehow mounted wrong(really not possible), then no thrust, no takeoff.

Pusher props do the same thing, just push rather than pull.

P38 had counter rotating props, makes for an easier takeoff with really big engines. Big bombers, all the props turned the same direction. That was mostly for ease of maintenance, supply, parts..4 identical engines rather than 2 specific types.

[Chance]

Do all prop driven aircraft have the prop going the same way, or do they vary?

Seems they vary.

The propellers on both engines of most conventional twin-engined aircraft spin clockwise (as viewed from the pilot seat). Counter-rotating propellers generally spin clockwise on the left engine and counter-clockwise on the right. The advantage of such designs is that counter-rotating propellers balance the effects of torque and p-factor, eliminating the problem of the critical engine.

http://en.wikipedia.org/wiki/Counter-rotating_propellers

[dogdriver]

Long answer, which boils down to , "It depends".

Most single engine airplanes made by western manufacturers have props which spin clockwise, which torques the airplane slightly to the left in a climb (like OldP said, the prop is actually creating lift by spinning and the right, or descending, half of the rotation creates more thrust due to the "angle of attack" of the airplane resulting in the prop blades being at a more efficient angle on the right half of the rotation than the left. But I digress...). To compensate for this torque, the pilot needs to press the right rudder in a climb so that the airplane flies in a "coordinated" manner (think a car in a skid going slightly sideways if he doesn't use the rudder).

To complicate matters, some former Eastern Block airplanes (the Yak 52 and Yak 55 come to mind) have radial engines with props that spin counter-clockwise. This requires the opposite pilot input, and will impress the h$!! out of you if you forget and push the wrong rudder when doing aerobatics (so I've heard...).

Back to the USA, most two engine airplanes have props which counter rotate so that the prop is rotating downward when closest to the fuselage. This positions the majority of the thrust closest to the centerline of the airplane, creating thrust more efficiently, making the airplane easier to control if one engine fails, producing symmetrical thrust if both engines are running (no rudder required in the climb) and avoiding a condition called a "critical engine"-- The old joke is that if your critical engine fails on a multi, the other engine will take you all the way to the crash site.

Kind of a Reader's Digest version, lots of good stuff about this on the Interwebs.

[dogdriver]

Can helicopters fly upside down ?

Once.

Another question:

Q: Do you need a parachute to skydive?

A: No. You need a parachute to skydive twice.

[thinpin]

Once.

Another question:

Q: Do you need a parachute to skydive?

A: No. You need a parachute to skydive twice.

I like a belly laugh at the end of my day.

[Bruce K]

All fixed wing pilots know that helicopters don't really fly at all.....

They're so ugly the Earth repels them.

:eek:

(rim shot please !)

BK

[Bruce K]

Seriously, helicopters can fly upside down with special modifications.

See the red Bull Eurocopter video from Oshkosh 2009:

http://www.youtube.com/watch?v=ug76TCVsvrA

Enjoy!

BK

[Chance]

Seriously, helicopters can fly upside down with special modifications.

See the red Bull Eurocopter video from Oshkosh 2009:

http://www.youtube.com/watch?v=ug76TCVsvrA

Enjoy!

BK

Cool video. To the casual observer it looks more like a controlled fall rather than flying. Doesn't look like he can get much if any lift while upside down like an airplane can.

[mvrider]

A little off-topic, but this reminds me of the Sopwith Camel, which took advantage of the torque-steer effect of its heavy radial engine to increase turning rate, in one direction.

"the crankshaft remained fixed while the cylinders and attached propeller rotated around it. The result of this torque was a significant "pull" to the right. In the hands of an experienced pilot, this characteristic could be exploited to give exceptional manoeuvrability in a dogfight. A 3/4 turn to the right could be done in the same time as a 1/4 turn to the left."


http://en.wikipedia.org/wiki/Sopwith_camel (http://en.wikipedia.org/wiki/Sopwith_camel)

[eddief]

for a bike related forum?

[Mark McM]

A little off-topic, but this reminds me of the Sopwith Camel, which took advantage of the torque-steer effect of its heavy radial engine to increase turning rate, in one direction.

I think you mean 'rotary engine'. A traditional radial engine has its block/cyliners fixed to the fuselage, and the rotating crankshift turns the propellor. On a rotary engine, the crankshaft is fixed to the fuselage, and the rotating block/cylinders turn the propellor.

[pdmtong]

for a bike related forum?

the forum seems to have become a place where any kind of discussion, save for politics, religon and the tiring hitler video are tolerated...

[Jaq]

Beware. Massive post follows.

Pretty much 99% of the world’s single-engine, reciprocating-engine aircraft (prop planes to you and me) have props that, when seated behind the engine, appear to rotate in a clock-wise direction. The main reason for this is that engines, since their invention, have turned in that direction. When people finally got around to bolting props to engines, it required far less gearing to keep the direction of the prop the same as the engine.
Out of that came uniformity and ease of maintenance. An engine that turns a prop in the opposite – widdershins – direction not only requires extra gearing, but counter-clockwise propellers have to be manufactured as such; you can’t just bolt a prop on backwards.

Well, you probably could, if it was what’s called a “fixed-pitch” prop, but it wouldn’t work as well. If it was a variable-pitch propeller, it wouldn’t work at all.

However, there are some multi-engine, piston and turbine engine aircraft that have what are called “counter-rotating” propellers (there are even some exotic single-engined aircraft with counter-rotating propellers, but they’re a rarity). The main reason for this is to balance out the tendency of twin engine aircraft to turn, or “yaw”, because of the forces created by the spinning propellers. Having two propellers on either side of the aircraft spinning in opposite directions balances out (or cancels) these forces while both engines are in operation. The Cessna 310, a twin-engine, piston aircraft, has a couple variants that have counter-rotating props.

(note: as an example of the forces of yaw, the P-51 Mustang swung such a massive propeller that, if over-revved too quickly on the ground, would turn the plane, lift the tail, and chew the pavement. Still more dangerous was the F4U Corsair; the prop at full speed created so much torque that, on carrier landings (which called for full-power the instant the wheels touch the deck in case of a go-around), a pilot had to almost literally stand on the opposite rudder pedal just to keep the plane from twisting out of control. Even after the Corsair was in the field, it took almost a year before they were certified for carrier operation. There’s even a story about a Texas millionaire back in the day who wanted to get rid of his wife but didn’t want to pay alimony. So he bought her a Corsair and she promptly killed herself.)

As for the big aircraft you mentioned, B-17s, Lancasters, B-29s, etc., they all had conventionally rotating engines; the aircraft are so huge, and their control surfaces so massive, particularly their empennage (rudder & elevators), that the yaw created by the spinning props wasn’t worth the extra headaches, especially in wartime when ease of maintenance was critical to mission success.

Pusher-props still rotate in a clockwise direction (as seen when sitting behind the engine); the difference being in the design of the propeller. As others have mentioned, props are just small wings that spin through the air and create lift (called thrust). As wings, their sections are those of airfoils (they look like elongated tear-drops when shown in cross-section) and have very precise camber (curvature) for the direction of spin.

There was, years ago, an interesting Cessna called the 337; there aren’t many flying today. It had two engines, one a “tractor” (or pulling) and the other a pusher mounted on the centerline of the fuselage. They made a unique sound and were really cool, but took a special rating to fly (multi-engine, centerline-thrust).

Lastly, we’ll talk about variable-pitch propellers. Most simple, single-engine aircraft have fixed-pitch propellers. But as aircraft get more complex, they have propellers that are adjustable by the pilot. This is for efficiency and, in the case of twin-engine planes, also for safety. A twin-engine plane that loses one engine can “feather” it’s props so that the blades are parallel to the slipstream, thus greatly reducing the drag and the tendency of the airplane to yaw (turn) toward the dead engine.

Some of these planes, particularly more modern, commercial versions, actually have the ability to change the pitch of the blades to the point that they will actually produce thrust in the opposite direction – thrust reversing – and slow the aircraft on the ground. However, there have been one or two accidents caused by flight crews accidentally reversing thrust too soon (while still in flight, though usually while on approach to landing (when the plane is already at lower airspeeds), causing the plane to stall and literally drop out of the sky.

[Jaq]

for a bike related forum?

Since the Wright Brothers were, in fact, bicycle makers, I would say that there's an almost holy connection between bikes and flying.

[Seramount]

for a bike related forum?

the subject header indicates that the contents are CLEARLY not bike-related, so
why did you even bother to read this thread?

if whining should become an Olympic sport, there's some potential medalists here.

[Jaq]

I think you mean 'rotary engine'. A traditional radial engine has its block/cyliners fixed to the fuselage, and the rotating crankshift turns the propellor. On a rotary engine, the crankshaft is fixed to the fuselage, and the rotating block/cylinders turn the propellor.

+1. Rotary engines, such as the Gnome, created relatively huge amounts of torque because of the sheer mass of the prop and the engine all rotating in the same direction. As a result, turns in the opposite direction could be lightning fast, while turns in the same direction (as the engine turned) could be more sluggish.

Not just the Sopwith Camel, but the Sopwith Pup, the 1 1/2 Strutter (the world's first carrier aircraft), the Sopwith Triplane, the Neiuport 17 & 28, the Fokker Eindekker, the Fokker DR1 (the triplane made famous by the Red Baron) and others all had rotary engines.

One of the problems, btw, with WWI aircraft is that they all tended to use Castor Oil as a lubricant. After a few hours of breathing in a bit of caster-oil exhaust, pilots would come back to Earth with a case of the screaming s--ts. Thus did cheese and currant juice become a staple of the mess table.

For those of you on the east coast, pay a visit to the Old Reinbeck Aerodrome in New York; he's got a fabulous collection of working WWI aircraft. On the west coast, there were a couple guys out at Paso Robles airport who had some WWI planes, and there used to be a fellow at Santa Maria airport that was building up something of a museum. Don't know if he's still around there.

[eddief]

just a little joke. you know prop, proper :). no reason to constrict on my account.

the subject header indicates that the contents are CLEARLY not bike-related, so
why did you even bother to read this thread?

if whining should become an Olympic sport, there's some potential medalists here.

[merlinmurph]

Can helicopters fly upside down ?

Not sure if there are any full-scale 'copters that can fly inverted, but you would not believe what a model helicopter can do with the right guy on the sticks. It called 3D flying. Search YouTube for "model helicopter aerobatics". Here's some I came up with - here (http://www.youtube.com/watch?v=NbezhpX4rC0)and here (http://www.youtube.com/watch?v=E_oE66MEYxQ).

[SoCalSteve]

just a little joke. you know prop, proper :). no reason to constrict on my account.

I got it!

[saab2000]

for a bike related forum?

The Wright Bros. were bike makers.

[Bruce K]

Saab!

Nice to see you back

My son was asking about you.

He has now completed single and multi instrument and commercial and has started CFI. He also going to get tail dragger cert and then get checked out in a Super Decathlon and an Extra

BK

[GregL]

The Cessna 310, a twin-engine, piston aircraft, has a couple variants that have counter-rotating props.

First off, my sincere "thanks" and respect to Jaq for an excellent post. As an aeronautic engineer and "retired" commercial pilot, I've very much enjoyed this thread. Jaq's post was so good I had (almost) zero need to respond. However, I'm also an amateur aviation historian, so I feel the need to make one minor correction. The Cessna 310 never had counter-rotating props. I believe you may be referring to the Piper Navajo, which had several varients (the C/R and Chieftain come to mind) which did in fact have counter-rotating props. I have around 1,000 hours in the Chieftain.

The Navajo Chieftain was a very capable light twin, but needed 100% effort on the part of the pilot if an engine quit. Indeed, my first chief pilot told me that the purpose of the second engine was to "take you to the scene of the crash" if one engine failed. It wasn't really that bad, but I was always very careful to stay within weight/balance limits and paid close attention to runway length and departure obstacles. In that regard, it was great training for the jets that followed in my career.

- Greg

[dave thompson]

for a bike related forum?

Yes, it's interesting.

[saab2000]

Saab!

Nice to see you back

My son was asking about you.

He has now completed single and multi instrument and commercial and has started CFI. He also going to get tail dragger cert and then get checked out in a Super Decathlon and an Extra

BK

The Extra would be cool. Believe it or not, I don't even have a single-engine commercial. I don't know if my ATP includes S/E privileges or not but I don't think so. Haven't flown that type of airplane in years.

Tell him to contact me if he has any questions. You know how to reach me by PM. Don't use the e-mail address attached to this forum. I never check it anymore.

Things are about to get interesting in the airline world what with the first guys and gals hitting 65 starting around Dec. 14 and the retirements are massive in the next couple years.

As to prop airplanes? This is the ultimate prop airplane ever.

http://www.youtube.com/watch?v=9xyag3Dx04Q

http://en.wikipedia.org/wiki/Tupolev_Tu-95

http://cdn-www.airliners.net/aviation-photos/photos/1/6/8/1660861.jpg

[Jaq]

First off, my sincere "thanks" and respect to Jaq for an excellent post. As an aeronautic engineer and "retired" commercial pilot, I've very much enjoyed this thread. Jaq's post was so good I had (almost) zero need to respond. However, I'm also an amateur aviation historian, so I feel the need to make one minor correction. The Cessna 310 never had counter-rotating props. I believe you may be referring to the Piper Navajo, which had several varients (the C/R and Chieftain come to mind) which did in fact have counter-rotating props. I have around 1,000 hours in the Chieftain.

The Navajo Chieftain was a very capable light twin, but needed 100% effort on the part of the pilot if an engine quit. Indeed, my first chief pilot told me that the purpose of the second engine was to "take you to the scene of the crash" if one engine failed. It wasn't really that bad, but I was always very careful to stay within weight/balance limits and paid close attention to runway length and departure obstacles. In that regard, it was great training for the jets that followed in my career.

- Greg

Golly. Thanks for the compliments. I think the 310 variants were after-market customizations. I remember a 310 sitting on the line when I was getting my license and my CFI explaining the counter-rotating props, and that it was silly-expensive to maintain.

Oh, and I forgot that the P-38 Lightning had counter-rotating props.

Here's one of my favorite strange a/c, the Shinden (Magnificent Lightning)

http://upload.wikimedia.org/wikipedia/commons/8/8e/J7w.png

[deanster]

Didn't some of the VTOL experimental planes use counter rotating props for neutrilizing torque while taking off and landing...not a big success in any case.

[Louis]

Didn't some of the VTOL experimental planes use counter rotating props for neutrilizing torque while taking off and landing...not a big success in any case.

Lockheed XFV-1

http://upload.wikimedia.org/wikipedia/commons/3/31/Lockheed_XFV-1_on_ground_bw.jpg

[deanster]

Lockheed XFV-1

http://upload.wikimedia.org/wikipedia/commons/3/31/Lockheed_XFV-1_on_ground_bw.jpg

Thanks. Haven't seen a photo of one of those in years. The props look like a hybrid between a WWII fighter and a chopper.

[Marburg]

If I recall correctly (and I probably don't), the one of the reasons for the counter-rotating two-prop schemes was because, in essence, they could make engines which were ``too torquey'' to efficiently drive a single prop. Even with many, many blades, the engines were capable of driving a prop so large (of such great diameter) that the tips would approach the speed of sound.

So the second row of blades is, in effect, an effort to scrape a bit more work from the engine with a practical sized prop.

(in addition to the torque reasons, of course)

Also, (and I believe others have corroborated this), in most multi-engine aircraft the engines all turn the same direction, no? If nothing else this avoids the need to build and maintain separate left-hand and right-hand engines.

[FlashUNC]

Helicopters don't fly. Rather they just beat the air into submission.

[oldpotatoe]

The Extra would be cool. Believe it or not, I don't even have a single-engine commercial. I don't know if my ATP includes S/E privileges or not but I don't think so. Haven't flown that type of airplane in years.

Tell him to contact me if he has any questions. You know how to reach me by PM. Don't use the e-mail address attached to this forum. I never check it anymore.

Things are about to get interesting in the airline world what with the first guys and gals hitting 65 starting around Dec. 14 and the retirements are massive in the next couple years.

As to prop airplanes? This is the ultimate prop airplane ever.

http://www.youtube.com/watch?v=9xyag3Dx04Q

http://en.wikipedia.org/wiki/Tupolev_Tu-95

http://cdn-www.airliners.net/aviation-photos/photos/1/6/8/1660861.jpg

Flew wing on more than a few Bears while on WestPac cruises. Very entertaining..as they found the ship and then proceeded to fly thru the pattern. Same for Badgers.

http://en.wikipedia.org/wiki/Tupolev_Tu-16

For SAAB, I got my private ticket, then Multiengine commercial, centerline thrust in the F-4 Phantom(just a FAA guy looking at my logbook), then Multiengine(non CL thrust) in the F-14...then my ATP but my license still says SE private privlidges(??)..

[oldpotatoe]

All fixed wing pilots know that helicopters don't really fly at all.....

They're so ugly the Earth repels them.

:eek:

(rim shot please !)

BK

They beat the air into submission...unnatural act, helicopters.

[guyintense]

One of the most amazing planes I've ever seen was the Red Baron, a highly modified P51 Mustang, it had a Rolls-Royce Griffon engine and contra-rotating propellers.
Unfortunately I was there when Steve Hinton stuffed it into a side of a mountain at the Reno air races in 79. A really, really bad way to end a great week of racing.

[mdeeds71]

Seems like this is a good ground school.

Nothing to add...all good.

As for the ATP...Most certificates will have a multi-engine on them for ATP as most are looking for airline or multi-engine applications. A candidate only tested in a SE will have ATP privileges limited to ASEL
So an average airline pilot license will have:

ATP: Airplane ME Land followed by type ratings such as 757 767 etc
then it would say commercial privileges ASEL.

If they were tested for ATP in both AMEL and ASEL then it would say:
ATP: Airplane ME Land, SE Land followed by type ratings etc.

[oldpotatoe]

Seems like this is a good ground school.

Nothing to add...all good.

As for the ATP...Most certificates will have a multi-engine on them for ATP as most are looking for airline or multi-engine applications. A candidate only tested in a SE will have ATP privileges limited to SE.

So an average airline pilot license will have:

ATP: Airplane ME Land followed by type ratings such as 757 767 etc
then it would say commercial privileges ASEL.

If they were tested for ATP in both AMEL and ASEL then it would say:
ATP: Airplane ME Land, SE Land followed by type ratings etc.

What I did, got an ATP in a Barron....required for United(busted Frasca, actually good news). Commericial privs, ASEL..

too bad I can't afford to fly anymore-rich man's sport. makes bicycles look like, well, like toys.

[saab2000]

What I did, got an ATP in a Barron....required for United(busted Frasca, actually good news). Commericial privs, ASEL..

too bad I can't afford to fly anymore-rich man's sport. makes bicycles look like, well, like toys.

I can't afford to fly either, which is why I work for an airline. We carry 'sponsors' who pay us to do it! Or as we call them, self-loading cargo... :D

[Jaq]

What I did, got an ATP in a Barron....required for United(busted Frasca, actually good news). Commericial privs, ASEL..

too bad I can't afford to fly anymore-rich man's sport. makes bicycles look like, well, like toys.

It's crazy these days. I got lucky years ago; a friend bought a 182 that he lets me fly for the cost of fuel + a little extra. Even so, I'm not putting in nearly the hours I used to. Just too damned expensive. I'm not sure what what rental prices are, though there's a fellow that runs an FBO down at Long Beach and they rent Cirruses for something like 250 an hour wet, with a 10-hour block-time discount at the low, low, low price of 245.

I thought all the military pilots came out of the service with a single & multi-engine land & instrument rating, but limited to jet engines, meaning you just had to get a sign-off to operate piston/prop a/c. Does anyone do basic with piston/prop planes in the military?

[saab2000]

I thought all the military pilots came out of the service with a single & multi-engine land & instrument rating, but limited to jet engines, meaning you just had to get a sign-off to operate piston/prop a/c. Does anyone do basic with piston/prop planes in the military?


Military folks still step to the front of the line for the best jobs. Thousands of hours of actual PIC time flying civilian jets with passengers is still not worth much (read: nothing) if you're up against a guy whose squadron buddy with possibly even several hundred hours flying jets is in the training dept. at a major airline.

[PanTerra]

just a little joke. you know prop, proper :). no reason to constrict on my account.Oh man! That flew right over my head. :banana:

[oldpotatoe]

It's crazy these days. I got lucky years ago; a friend bought a 182 that he lets me fly for the cost of fuel + a little extra. Even so, I'm not putting in nearly the hours I used to. Just too damned expensive. I'm not sure what what rental prices are, though there's a fellow that runs an FBO down at Long Beach and they rent Cirruses for something like 250 an hour wet, with a 10-hour block-time discount at the low, low, low price of 245.

I thought all the military pilots came out of the service with a single & multi-engine land & instrument rating, but limited to jet engines, meaning you just had to get a sign-off to operate piston/prop a/c. Does anyone do basic with piston/prop planes in the military?

You needed a NATOPS qual(essentially a type rating) and when I was in, an Instrument card(a actual card when I was in. (I had a green one, Special card, could take off in zero-zero-not sure why?/). Then a trip to the FAA with yer Natops and instrument card-Commercial and instrument ticket, plus some $. Not all military aviators did/does this. Not sure why, it's essentially a freebie...

Why my first was a CMEL, centerline thrust(F-4), then changed it to CMEL for the Turkey(F-14).