Flat spins

Mtns2Skies

Mtns2Skies

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Mtns2Skies
I know flat spins are the most dangerous type, but how would you enter one?
 
Load the aircraft with an aft CG, and stall uncoordinated is one way.
 
Bill Kershner did a lot of research on spins. In his Basic Aerobatic Manual, he discusses spin mechanics. There's also another book I have titled, Facts About Spins. It's tucked away in a box right now and I cannot recall the author's name.

You can learn much from both but have a good understanding of basic aerodynamics before you dig in further.
 
HawkEye007 said:
I know flat spins are the most dangerous type, but how would you enter one?
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Don't. Many airplanes won't recover from such a spin. Aft CG is one way that will do it, but some of the later Cessna 150s would also tend to go flat after several turns, even with CG where it was supposed to be. Cessna had to issue a POH supplement calling for abrupt, full down-elevator while holding opposite rudder. And they meant ABRUPT, FULL-DOWN. Like that. One of our instructors and a student got flat once, and no amount of recovery seemed to work until they used Cessna's brutal method, and they got out of it at 800 feet or so. Less than two turns to impact.
Airplanes that have a large moment of inertia will flatten out easily. The weight of the airplane ahead of the CG must balance the weight of the airplane behind the CG, and if those two weights are far from the CG the inertia is greater than if they're close. So an airplane that has its engine mounted farther forward to balance a tail-heavy condition has this larger inertia, and as it begins to rotate the two weights want to come into the same plane of rotation. The nose rises, the tail falls, and the spin is flat. Trouble ahead if the airplane wasn't approved for spins, see. My Jodel came out tail-heavy, the engine is a long ways farther forward than the design called for so that the CG is where it's supposed to be, so I never spin it. Ever. It will not respond like a stock Jodel, and I'm not going to research it. Not at my age.


Dan
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Dan Thomas said:
Don't. Many airplanes won't recover from such a spin. Aft CG is one way that will do it, but some of the later Cessna 150s would also tend to go flat after several turns, even with CG where it was supposed to be. Cessna had to issue a POH supplement calling for abrupt, full down-elevator while holding opposite rudder. And they meant ABRUPT, FULL-DOWN. Like that. One of our instructors and a student got flat once, and no amount of recovery seemed to work until they used Cessna's brutal method, and they got out of it at 800 feet or so. Less than two turns to impact.
Airplanes that have a large moment of inertia will flatten out easily. The weight of the airplane ahead of the CG must balance the weight of the airplane behind the CG, and if those two weights are far from the CG the inertia is greater than if they're close. So an airplane that has its engine mounted farther forward to balance a tail-heavy condition has this larger inertia, and as it begins to rotate the two weights want to come into the same plane of rotation. The nose rises, the tail falls, and the spin is flat. Trouble ahead if the airplane wasn't approved for spins, see. My Jodel came out tail-heavy, the engine is a long ways farther forward than the design called for so that the CG is where it's supposed to be, so I never spin it. Ever. It will not respond like a stock Jodel, and I'm not going to research it. Not at my age.


Dan
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Thank you very much!
 
Dan Thomas said:
Don't. Many airplanes won't recover from such a spin. Aft CG is one way that will do it, but some of the later Cessna 150s would also tend to go flat after several turns, even with CG where it was supposed to be. Cessna had to issue a POH supplement calling for abrupt, full down-elevator while holding opposite rudder. And they meant ABRUPT, FULL-DOWN. Like that. One of our instructors and a student got flat once, and no amount of recovery seemed to work until they used Cessna's brutal method, and they got out of it at 800 feet or so. Less than two turns to impact.
Airplanes that have a large moment of inertia will flatten out easily. The weight of the airplane ahead of the CG must balance the weight of the airplane behind the CG, and if those two weights are far from the CG the inertia is greater than if they're close. So an airplane that has its engine mounted farther forward to balance a tail-heavy condition has this larger inertia, and as it begins to rotate the two weights want to come into the same plane of rotation. The nose rises, the tail falls, and the spin is flat. Trouble ahead if the airplane wasn't approved for spins, see. My Jodel came out tail-heavy, the engine is a long ways farther forward than the design called for so that the CG is where it's supposed to be, so I never spin it. Ever. It will not respond like a stock Jodel, and I'm not going to research it. Not at my age.


Dan
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Outstanding response Dan!:yes:
 
HawkEye007 said:
I know flat spins are the most dangerous type, but how would you enter one?
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Depends on the aircraft, but in some cases, a good way is to screw up the recovery from a normal spin by putting the stick forward first before using the rudder to stop the rotation. Thay way (again, in some aircraft), you get to spin all the way into the ground thinking that you are attempting to recover...

At 1:20 into this video http://youtube.com/watch?v=7oP2H_H4_gc, you can see what happens when the stick goes forward in a spin - doesn't flatten out much in this example, but it does accelerate the rotation significantly.

Power is another way.

"Learn yourself aerobatics" is not a good idea.
 
Airplanes that have a large moment of inertia will flatten out easily.
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The Grumman AA1x series will flat spin if you let the spin get aggravated. The cure is to shove yourself against the windscreen as one test pilot found out spinning an AA1. The AA5 series (Traveller, Cheetah, Tiger) are not as prone to this probalby because their fuel tanks are close to the wing route vs. the AA1 fuel tanks being near the end of the wing.
 
HawkEye007 said:
I know flat spins are the most dangerous type, but how would you enter one?
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If you'e not quick to pull the power, the spin will flatten.

Several types are so marginal in this condition they require pro-spin aileron so that the outside wing is generating dynamic drag.
 
HawkEye007 said:
I know flat spins are the most dangerous type, but how would you enter one?
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The most dangerous type of spin is in an aircraft not approved for spins. So my question would be, why do you "know that flat spins are the most dangerous?" I do flat spins all the time in my Pitts and they're not any more dangerous than any other maneuver I do. It's just another maneuver that you should be familiar with if you're going to be doing spins.

In my experience, you know you've met a BS artist when they start talking about unrecoverable flat spins or especially the unrecoverable inverted flat spin. Uh huh - again, just another maneuver if you're flying an aircraft that's approved for the maneuver and it's loaded properly. If one or both of those conditions aren't met, then they're all dangerous. The next thing the BS artist will tell you after they start talking about the unrecoverable flat spin they got into will be that they "tried everything they could think of and it finally recovered just in time." My response to that is that there's a proper flat spin exit technique that I'm guessing wasn't anything "they thought of" and they accidently hit upon it before they became airplane pizza.

Spins are, for whatever reason, a subject with a high BS factor around the FBO coffee pot. My advice would be to forget the books recommended and just go get some dual from a really good aerobatic instructor in a machine really designed for the purpose. Enlightenment is yours for the price of a hour or two of dual...
 
Hawkeye, it's my understanding that you are 13 years old? Is that right? Can you fit into a parachute yet?
 
i guess you could always pass close behind an F15 but dang they retired them didnt they?
 
HawkEye, I wasn't trying to flame you or anything like that. To quote Ellen Degeneris "my point, and I do have one..." is that some pilots are fearful of spins specifically and aerobatic flying in general because of the stuff you hear around the coffee pot at most flight schools. I believe it's the #1 reason why more pilots don't explore aerobatic and spin training. It's a real shame too because I think there's a lot of pilots, even high time pilots, that have spent their time in the air living with some amount of fear of the unknown. All that fear could be effectively dealt with if there were less uninformed information spread around and more pilots felt safe in seeking out the dual training I referred to in my other post. Of course, if you're not flying age, then by all means get your hands on everything you can read. Allen Cassidy's "Better Aerobatics" and Bill Thomas' "Fly for Fun" are both great books that can be ordered from the EAA/IAC web sites.

Apologies to all if I came across heavy. You're going to hear a lot of stuff in flying that is said authoritatively but is far from it. It's always interesting to ask someone going on about "flat spins" for example, where they got their training and how many they've actually done themselves. Not to challenge them, but so you know if you should pay any heed to what you're hearing.
 
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Good morning Wes. :) Hey, are you going to OSH? If so I would love to get the chance to meet you.

PittsDriver said:
Apologies to all if I came across heavy.
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No worries. :)

PittsDriver said:
You're going to hear a lot of stuff in flying that is said authoritatively but is far from it.
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There is a LOT of that, seems like. It takes a while to figure out who REALLY knows what they are talking about. :yes:
 
PittsDriver said:
The most dangerous type of spin is in an aircraft not approved for spins. So my question would be, why do you "know that flat spins are the most dangerous?" I do flat spins all the time in my Pitts and they're not any more dangerous than any other maneuver I do. It's just another maneuver that you should be familiar with if you're going to be doing spins.
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Actually I believe the Jeppesen book said they are the most dangerous. But I don't know you may be right I've never been in a flat spin so...

Also you did not come across heavily at all I think that was the most polite way you could have put it
 
Anthony said:
LOL! However, I don't think the F-15 is far behind with the F-22 and F-35 hitting the inventory.
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Ahhhh, yup, but I just couldn't pass up the TG ref. "He's in a flat spin...He's headed out to sea."
 
Diana said:
Good morning Wes. :) Hey, are you going to OSH? If so I would love to get the chance to meet you.
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Alas, no. It seems like I'm destined to hit up the show about every two years. The only week that worked this year for our family vacation just happened to be the same week as AirVenture.

I'm seriously considering going to the Nationals this year though. Any chance you'll make the trek to Texas?

I think volunteering in the IAC pavilion would be an excellent use of an half day at the show. After all, what could be better than a place out of the sun and hanging out with acro folks?

Wes
 
PittsDriver said:
I'm seriously considering going to the Nationals this year though. Any chance you'll make the trek to Texas?
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I won't be going...don't even know if I well compete at KC again. Maybe if I can get some more instruction or critiquing. Have you been to Nationals before?

PittsDriver said:
I think volunteering in the IAC pavilion would be an excellent use of an half day at the show. After all, what could be better than a place out of the sun and hanging out with acro folks?
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Yea, now that you mention it....sounds like a great idea. I probably will. :yes:
 
Diana said:
I won't be going...don't even know if I well compete at KC again. Maybe if I can get some more instruction or critiquing. Have you been to Nationals before?

Yea, now that you mention it....sounds like a great idea. I probably will. :yes:
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Bob Stark, one of the top Unlimited pilots in the US told me at my first contest that if you want to fly better, you fly more, right? So, if you want to fly better contests, you have to fly more contests. Some of the best advice I ever got. Don't let the competitive Diana get in the way of the fun loving Diana and just go compete!
 
PittsDriver said:
Bob Stark, one of the top Unlimited pilots in the US told me at my first contest that if you want to fly better, you fly more, right? So, if you want to fly better contests, you have to fly more contests. Some of the best advice I ever got. Don't let the competitive Diana get in the way of the fun loving Diana and just go compete!
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Wes, you have a good point. :yes: I would probably have more fun if it wasn't likely that I will come in last again. :D Although, it will be great to see some of the people again. :yes:
 
Diana said:
Wes, you have a good point. :yes: I would probably have more fun if it wasn't likely that I will come in last again. :D Although, it will be great to see some of the people again. :yes:
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You just need to find a lower class of competitors. -lance
 
Diana, you just need to come to one of our east coast contests. Last place in primary will usually bring home the 3rd place trophy and sometimes the second place wood :) And, I will guarantee you that the fun you'll have will have no correlation on your standing at the end of the contest :)

Wes
 
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