Can you spin a multi-engine piston airplane with asymmetrical thrust?

N918KT

N918KT

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Hey guys, here is an interesting question to think about. Is it possible to spin a multi-engine airplane using asymmetrical thrust if the airplane is already stalled? Without using ailerons or rudders, if the engine thrust on one engine is greater than the other engine, would it be possible that the plane could spin if it is stalled already?
 
I don't see why not. Even B-17's spun during the war, at altitude. Sometimes due to flak / fighter damage, though. Often all the way to the ground. Seems that the Army Air Corps did not provide spin training at one time.
 
Absolutely.

To spin you need a stall and a yaw. You already have a stall and asymmetric thrust will create a yaw.
There is a chance you may be able to counteract it with the rudder until a certain point, but only until a certain point, because the engine is typically a lot more powerful than your rudder.
 
Wow, that's interesting! Has anyone tried spinning a multi-engine plane using asymmetrical thrust, if that plane is certified for spins?
 
N918KT said:
Wow, that's interesting! Has anyone tried spinning a multi-engine plane using asymmetrical thrust, if that plane is certified for spins?
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Don't know from the top of my head. You may want to search some of Matt Younkin's videos, I bet you he's done it on video.
 
I doubt you'd get a clean spin. Most likely would get a spiral as the thrust will create a lifting moment on the operative engine. If you've seen any videos of a ME lose it (usually close to ground) they progress this way. They are mislabeled as stall-spin accidents.

Just my hypothesis
 
N918KT said:
Wow, that's interesting! Has anyone tried spinning a multi-engine plane using asymmetrical thrust, if that plane is certified for spins?
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I am not aware of any twin certified for spins and twins as a rule are not required to be spin tested for certification.

Lots of people have spun twins. Most of them are dead.
 
MachFly said:
Don't know from the top of my head. You may want to search some of Matt Younkin's videos, I bet you he's done it on video.
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I am willing to bet he hasn't. I don't know of any twins that have been spin tested. Doesn't mean they haven't.
 
Fearless Tower said:
I am not aware of any twin certified for spins and twins as a rule are not required to be spin tested for certification.

Lots if people have spun twins. Most of them are dead.
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That's what I thought. I think just about all twins are not certified for spins.
 
Jaybird180 said:
I doubt you'd get a clean spin. Most likely would get a spiral as the thrust will create a lifting moment on the operative engine. If you've seen any videos of a ME lose it (usually close to ground) they progress this way. They are mislabeled as stall-spin accidents.

Just my hypothesis
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I don't think that's entirely correct. It's not hard to recover from a spiral, it can be hard to recover from a spin.
 
MachFly said:
I don't think that's entirely correct. It's not hard to recover from a spiral, it can be hard to recover from a spin.
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Wait, is there a difference between a spiral and a spin? I thought they are the same thing.
 
N918KT said:
Wait, is there a difference between a spiral and a spin? I thought they are the same thing.
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Spirals happen when you are not stalled and the speed is usually high. The procedure for recovering from that is cut power and roll level, then pitch up to level alt. Kinda looks like a descending steep turn from the side.
 
MachFly said:
Spirals happen when you are not stalled and the speed is usually high. The procedure for recovering from that is cut power and roll level, then pitch up to level alt. Kinda looks like a descending steep turn from the side.
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You know guys in NY , NJ area where it is possible to take spin training , thank you
 
MachFly said:
Spirals happen when you are not stalled and the speed is usually high. The procedure for recovering from that is cut power and roll level, then pitch up to level alt. Kinda looks like a descending steep turn from the side.
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There are many airplanes where pilots are attempting to spin and improper technique or designed spin resistance results in a spiral.
 
Vitaly said:
You know guys in NY , NJ area where it is possible to take spin training , thank you
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You can find a list of IAC (International Aerobatics Club) recommended schools here: http://www.iacusn.org/schools/. I'm sure they will all be able to provide you will good spin training.

I know a number of regular schools (that mainly teach primary students) say they do spin training. If you end up doing it with them find out how proficient the instructors are with spins. Also do not do it in old 152s or 172s, because with time the amount of Gs the aircraft can pull deteriorates and when you recover from a spin you will need to do a high speed pull up out of a dive, there is a chance an old aircraft may not handle it.

Overall I recommend you do it in an aerobatic aircraft with a qualified instructor.

If you tell me what's the closest airport to you there is a chance I may be able to recommend you a specific school.
 
It is absolutely possible to spin a ME plane due to asymmetrical thrust.

However, you tend to get a *flat* spin instead of a normal one when it happens. Flat spins suck.

For a real good example of spinning an ME plane (granted, not a piston; but still an ME) because of asymmetrical thrust, read up on the fatalities associated with the F-14A.
 
Jaybird180 said:
There are many airplanes where pilots are attempting to spin and improper technique or designed spin resistance results in a spiral.
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That's exactly how my first ever "spin" went. In my defense I had less than 40 hours at the time.
 
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I hesitate to ask. This may be a dumb question.

If you get a twin in a spin, could you not just throttle up the engine on the wing moving backwards and throttle down the wing moving forward?
 
SixPapaCharlie said:
I hesitate to ask. This may be a dumb question.

If you get a twin in a spin, could you not just throttle up the engine on the wing moving backwards and throttle down the wing moving forward?
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If it's a normal spin, yes. In a flat spin, you'll be more worried about getting the nose down than breaking the spin itself.
 
SixPapaCharlie said:
I hesitate to ask. This may be a dumb question.

If you get a twin in a spin, could you not just throttle up the engine on the wing moving backwards and throttle down the wing moving forward?
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That's one of the recommended procedures. But you should still be using the rudder.

I've seen spin recovery procedures written in POHs of only two twins before (that I can remember), C414 and P-38. Every other POH just says that spins are prohibited.

C414 POH says:
1. Cut power on both engine.
2. Apply full rudder opposite direct of rotation.
3. Approximately 1/2 turn after applying rudder, push control wheel forward briskly.
4. To expedite recovery, add power to the engine toward the inside of the direction of the turn.
5. Pull out of the resulting dive with smooth, steady control pressure.

Note that the procedure may slightly change depending on the aircraft.
 
warthog1984 said:
It is absolutely possible to spin a ME plane due to asymmetrical thrust.

However, you tend to get a *flat* spin instead of a normal one when it happens. Flat spins suck.

For a real good example of spinning an ME plane (granted, not a piston; but still an ME) because of asymmetrical thrust, read up on the fatalities associated with the F-14A.
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A flat spin is more of a characteristic of swept wing jets with significant aft CG. Shouldn't be a problem with a straight wing (especially light) twin, your CG will be in front.
Otherwise in a spin with left rotation, adding power will pitch the nose up and flatten the spin. In a spin with right rotation, adding power will pitch the nose down and accelerate the rotation. With a heavier prop these effects will be more significant. So with correct power applications a flat spin should not be possible.
 
MachFly said:
If you want to read more about it there is a good article here: http://www.flightlab.net/Flightlab.net/Download_Course_Notes_files/10_Spins.pdf. "Ctrl F" for "Spin or Spiral?"
That file was written by Flight Lab, it's a test pilot school. You can trust their information.
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Here's what I said, stated differently at page 16 from your reference:

Spin or Spiral?
Spin-reluctant aircraft will often reward you with a spiral departure, until you figure out the trick of getting them to spin (rudder timing, blast of power, rapid deceleration leading to a higher angle of attack). You’ll immediately recognize a spiral departure, because the roll-off happens slowly. A spin departure will roll you faster. Opposite aileron will recover a spiral, but the resulting adverse yaw may aggravate a spin departure. Airspeed and z-axis load factor will increase in a spiral, and the ball will respond to your feet in the normal ways, remaining centered if your feet are off the rudders.
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My Dad had one of the first Twin Comanches and leased it back for instruction. Student and instructor got it in a spin with one engine. went all the way in and of course killed them. Airplane only had about 150hrs on it. Insurance paid for a new one. Don
 
MachFly said:
A flat spin is more of a characteristic of swept wing jets with significant aft CG. Shouldn't be a problem with a straight wing (especially light) twin, your CG will be in front.
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Flat spins may be more of a problem for swept-wings, but that doesn't mean they can't happen to straight wing twins.

A few years ago a twin turboprop flat spinned into the ground near Prescott. The airplane landed like a pancake - completely intact with no ground scar.
 
Fearless Tower said:
A few years ago a twin turboprop flat spinned into the ground near Prescott. The airplane landed like a pancake - completely intact with no ground scar.
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Interesting. I tried searching the NTSB database for that crash, couldn't find anyone. Would you happen to know any more details?
 
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MachFly said:
Interesting. I tried searching the NTSB database for that crash, couldn't find anyone. Would you happen to know any more details?
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I'll see if I can find something. I think it was something like a Cheyenne. They were flying as a chase plane with a jet warbird and were in formation trying to check out a reported problem with the jet. At some point as they were passing behind/underneath they lost control and crashed.
 
Fearless Tower said:
I'll see if I can find something. I think it was something like a Cheyenne. They were flying as a chase plane with a jet warbird and were in formation trying to check out a reported problem with the jet. At some point as they were passing behind/underneath they lost control and crashed.
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I can't find anything using keywords "prescott," "prc," and "kprc" with "formation" or "spin." Could it have been closer to one of the nearby airports?
 
MachFly said:
I can't find anything using keywords "prescott," "prc," and "kprc" with "formation" or "spin." Could it have been closer to one of the nearby airports?
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I used a search by city (Prescott, AZ) and narrowed it down to Part 91 Piper twin turbo-props fatal accidents.

Here it is:
http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20061026X01561&ntsbno=LAX07FA012&akey=1

In this case the cause of the loss of control was the jet blast essentially taking the T-tail of the Cheyenne off and the airplane ended up in what appears to be an inverted flat spin. The flat spin itself is not specifically mentioned in the report, but if you saw the news photos of the wreckage at the time, I can't imagine any other situation the airplane could have been at the time of impact.
 
Cpt_Kirk said:
http://youtu.be/3cJkjk0hOU8

Someone embed this, please.
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Great video. Thanks.
I read in Flying Magazine once where Beechcraft put the Travel Air through spins in the 1950's when they were selling it to the Army. From what I remember it was said that it recovered most of the time but not all of the time. I have not been able to find any reference to this test. Perhaps they confused the Dutchess test.

I did once have an incipient spin in a PA-34. The student was doing power on stalls. During one recovery he rapidly pushed both throttles forward, but for some reason one engine did not produce power. We were below Vmc so it was... interesting.
 
Fearless Tower said:
I used a search by city (Prescott, AZ) and narrowed it down to Part 91 Piper twin turbo-props fatal accidents.

Here it is:
http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20061026X01561&ntsbno=LAX07FA012&akey=1

In this case the cause of the loss of control was the jet blast essentially taking the T-tail of the Cheyenne off and the airplane ended up in what appears to be an inverted flat spin. The flat spin itself is not specifically mentioned in the report, but if you saw the news photos of the wreckage at the time, I can't imagine any other situation the airplane could have been at the time of impact.
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Thanks for finding that, very interesting.
Note to self, if I ever fly with a Mig-21...keep my tail out of his thrust flow.

Regarding the original question, I don't think this crash qualifies as a regular flat spin because he was missing a rather large part of the airframe.

If anyone is interested a few small pictures of the crash site can be found here: http://www.baaa-acro.com/Fiches%20d%27accidents/2006/N121CS.htm
 
MachFly said:
Regarding the original question, I don't think this crash qualifies as a regular flat spin because he was missing a rather large part of the airframe.
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True, certainly not a spin due to asymmetrical thrust. I mentioned it primarily in reference to the comment that flat spins were a swept wing problem.
 
Fearless Tower said:
True, certainly not a spin due to asymmetrical thrust. I mentioned it primarily in reference to the comment that flat spins were a swept wing problem.
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Don't get me wrong, they are certainly possible in a straight wing aircraft. It's just that they are more of a problem in a swapped wing aircraft and rather rare in a straight wing.

This particular Cheyenne thought isn't a typical straight wing aircraft, it didn't have a tail so that changes all it's aerodynamics. But you don't need to provide me with another flat spin accident, I know if you search the NTSB database for "flat spin" you'll get a few straight wings. I've also done it myself in the Pitts so I know first hand that it's possible.

Normal spin recovery procedure (which everyone learns) is to cut power in a spin. If you cut power flat spin shouldn't happen (in a straight wing), so that's why I'm saying that they are unlikely.
 
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