What is "deep stall" and "dead spin", recovery chutes ?

Question

what is "deep stall" and "dead spin", recovery chutes ?

what is the concise definition of

"deep stall" and "dead spin" ?

speed altitude AoA etc ?

can it be recoverable ?

are there fighters today that include

built-in parachute to recover from

"deep stall" and/or "dead spin" ?

approximately, what's the weight/size of

those recovery chute ?

can recovery chute deployed at any kind of

"deep stall" and "dead spin" ?

can recovery chute deployed at any AoA,

altitude and/or speed ?

thanks a lot ;)

Answer 1

Just a 'PS' to the other answers, who have explained things to quite an extent.

In the French Mirage III E, you could deploy the drag chute, in case it went into a flat spin, though it was not designed for this purpose, but to stop the aircraft on the runway. During air combat this series could go into a flat spin, from which recovery otherwise was not possible.

Answer 2

Deep stall and dead spin are two conditons that are very difficult ,and sometimes impossible, to get a plane out of. A deep stall is usually a problem fo aircraft with a T-tail. When a plane's ings stall, the airflow separation causes a massive wake of turbulence behind the wings. In t-tail configurations, this turbulent airflow can interfere with the elevator orperation at high angle of attack. Recovery from a deep stall can be impossible, resulting in a crash. Some aircraft with such characteristics are fitted with safety devices in the controls to prevent the aircraft from achieving a high enog AoA to do this. One device like this is a stick pusher, which forces the nose of the aircraft down whenever it begins to stall. Here's a diagram illustrating this:

http://upload.wikimedia.org/wikipedia/co...

A deep stall can also be a rarer situation in which an aircrafts forward airspeed is essentially zero. This means the plane is falling belly-first. Most aircraft cannot do this, but some fighters and heavier planes have in the past. It's rare because it is so extreme that most pilots won't get themselves into such a situation. This kind of stall can be unrecoverable without a lot of altitude and can lead to a dead spin or a "flat spin". Flat spins are different from typical spins as the nose is low and the aicraft seems to spiral in a normal spin and high, typically above the horizon, and the plane spins around on its belly like a disk in a flat spin. A flat spin has sideways or even reversed airflow over most control surfaces, whic combined with low speeds, rensers a lot of recovery efforts innefective. Recovery paracutes can be used, but are heavy and aren't usually equipped on production aircraft. They are, however, equipped for safety in test flight programs where the pilot will be testing the stall and spin characteristics of a plane. This device extends a parachute behind the plane to generate drag to pull the plane into a more favorable attitude. Here's a page describing such a system with pictures of the aparatus:http://www.butlerparachutes.com/spin.htm

Here's a picture of a YF-22 with such a device attached. The chute is housed in a red canister extended between the vertical stabilizers: http://www.wingsoverkansas.com/photos/f-...

These devices can be deployed under most conditions except high speed, but spins and stalls are really only a problem at low speed.

Answer 3

I understand "deep stall" characteristics because I flew the F-16,  a "dead spin" I have never heard of... are there fighters that have parachute recovery systems??  none that I am familiar with...  they have been developed for a few light civilian aircraft and have been deployed successfully.

Can it be deployed at any AoA etc... ??, well.. you can pull the handle, whether or not it does you any good... is another question.

Deep Stall, essentially is a flight regime in which you are not supposed to find yourself either accidentally or on purpose unless you are at Edwards and some engineer wanted you to really press your luck.  Most aircraft have dynamic stability designed into them for safety. The F-16 was designed for superior maneuverability and requires computer input to flight control surfaces to constantly maintain controlled flight.

If you depart controlled flight, your aircraft will typically transition those areas related to deep stall characteristics and go on to do something else. If you dropped a model airplane, even a bad one.... from a 10 story building, it would try to fly, and would pitch and roll and stall etc. If you dropped a book, it would not try and fly, it would just go earthward. When the aircraft is in a "deep stall" condition.. it is more akin to a book.

The air is passing the machine in such a manner that the control surfaces are useless... which all but guarantees that you won't have an engine either, since in order to keep it running you need air going in the inlet at a high (volume) rate to maintain operation. The F-16 flight computer is designed to prevent you from entering such a flight regime, and will not allow the pilot to do so, even accidentally. Aircraft can get into and out of deep stall regimes, the recovery being something similar to a rocking motion, where you encourage the a/c towards either end of the envelope, anything is better than no control, a stall is something that can be dealt with.. so even forcing the the airplane back into a typical stalled condition from which it can then recover, is better than just plummeting straight down.

A "Flat spin" is a spin where the nose is not as far below the horizon (assuming you are not inverted) as on a typical spin and this causes the tail to blanket the wing more than in a regular spin as far the flight controls are concerned, making recovery more difficult.

Civilian aircraft are designed with safety in mind, so you essentially must force a single engine aircraft into a spin, and then hold the controls to maintain the spin. If you just release the controls on MOST single engine piston civilian family type airplanes, the plane will come out of the spin by itself because of the work that went into it on the designers table.

Non-centerline thrust  Multi-engine a/c are much more likely to spin because of asymetric thrust (one engine inop)  and those stall/spin accidents are common and usually fatal.

Answer 4

I can answer about the recovery chutes. The Cirrus which has them factory installed as a parachute bag attached to the airframe which is attached to a rocket which deploys it. I am not sure of the exact weight but it looks like the whole system woudl weigh less than 100 pounds. The parachute itself is very large (55 foot diameter). There is a limitation on deploying the chute which is 133 knots.  The test showed that the aircraft was recovered from a spin in about 900 feet, and recovered from straight and level flight within about 500 feet. The pilot's manual reccomends deploying prior to 2000 above the ground. Essentially the chute should recover you as long as you are within the above parameters. You then hit the ground at 1700 feet per minute vertically which is 17knots or the equivalent of dropping 11-13 feet without a parachute so it is still a hard hit but many have walked away from their deployment in which they porbably would have otherwise died.

Answer 5

In order to get out of a stall, the nose must be lowered ot gain airspeed.  In a deep stall or flat spin, you can't get the nose to come down, so the chute is deployed. The drag causes the nose to come down, airspeed increases and you have broken the stall. The chute should only be deployed when stalled as airspeed will be slow. All will come off automatically when an airspeed is reached that the chute will not arrest. Drag chutes on aircraft fitted with them will rip off if deployed at too great a speed.

Answer 6

I've been flying for a few years now, I've done a lot of different types of flying, including aerobatics, and I have never heard of those two terms.

I think you may be thinking of a steep spiral, which is a normal spin (uncoordinated stall) which has became unstalled, but is still spinning. It is basically following a cork s***w pattern downwards.  No parachute would be necessarry for a recovery, just opposite rudder, level the wings, and pull up. No big deal.

I have heard a flat spin called a "death spin" before.  I don't fly military planes so I can't speak for them, but in small aerobatic planes a flat spin is just a normal spin with a little bit of power added.  It is totally recoverable, opposite rudder and break the stall. Again, no big deal as long as the CG is within limits.

Like every good pilot, I have watched Top Gun. That spin Goose got into is what I believe is a form of a flat spin, but I'm really not familiar with it.  I do believe it is a real thing that can happen. I remember hearing about  test pilots spinning planes with the CG too far aft, and they not being able to recover.  I read somewhere that to prevent this from happening on test flights they would equip planes with weights on the tail that could be released if it was ever impossible to recover from a stall (or spin). A parachute could do the same trick.

Maybe someone else knows about deep stalls and dead spins, but those are two terms I have never heard used.

Answer 7

"Dead spin?  --You mean "graveyard spiral"?