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# What is a spin

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i know many of you know but im not 100% althou i have a few theorys

the spin im talking about is the one refered to with regards to stall

is it a roll or more a spiraling dive ???

Thanks Troy

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Spin- what is it .

Why are you up so late disperse? This subject has been on this forum at great length before. Rather than dig those posts out , I would suggest that you look up all the excellent training material on the RAAus. site ,as a first step, and we can take it from there if you have any further queries . I mean this in the kindest way, not as a put-off. Regards ..Nev..

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Hi Troy,

Firstly you're right that a spin has something to do with a stall. Unless the wings are stalled you can't get a spin.

Imagine that you are stalling the aircraft and that at the point of stalling you suddenly kick in full left rudder. The aircraft, with its wings stalled, will yaw suddenly to the left. This will reduce the angle of attack of the right wing and increase the angle of attack of the left wing. The left wing is therefore more deeply stalled and so two things happen. The left wing drops - it is generating less lift than the right; and in so doing it increases its angle of attack (AOA) further. Because it is at a higher AOA than the right wing it is generating more induced drag than the right wing and so the aircraft will tend to yaw to the left, continuing the process that you started when you gave it a boot full of rudder.

You are now in what is called autorotation and after a turn or two this becomes a quite stable situation. The nose of the aircraft is pitched down - how much varies by aircraft and circumstance, the aircraft is rolling somewhat and yawing substantially. The critical thing is that the airspeed is lowish and does not increase. Often the ASI fluctuates in a spin. Height loss is considerable.

Many aircraft will not remain in a spin unless encouraged to do so. Others will require specific and vigorous actions to stop them spinning. Recovery is about unstalling the wings and stopping the yaw. You should speak with your instructor about specific recovery techniques as these need to be a clear and deeply understood response to the situation.

Now for clarity I spoke about spin entry by using sharp rudder input to aggravate a stall. Inadvertent spin entry can come about by stalling the aircraft in a turn or by stalling the aircraft in an unbalanced state. Imagine you are turning final, you are slow and you overshoot. Instead of turning in a balanced way like you should you kick in more rudder to get back on line and you pull harder. The aircraft stalls and enters an incipient spin (the first stage of a spin before it is stabilised). You have insufficient height for recovery and so you become a statistic.

Just an aside - often spin entry sees the aircraft flipping onto its back, with the nose dropping through before it stabilises. Considerable height is lost in this process and it's why stall/spin in the circuit is so dangerous - the aircraft hits the ground in an extreme nose down - sometimes semi-inverted - attitude that puts a lot of force directly into the cockpit area. Not good for pilots.

Further trivia aircraft can also be induced to spin inverted and spins can be flat or steeper in both upright and inverted spins.

Now a note of warning: As far as I know spins are not permitted in RAAus aircraft; our aircraft are not approved or flight tested for spins; spinning doesn't form part of our training syllabus; and aircraft recovery varies with aircraft type and with CofG. Some CofG positions can make spins unrecoverable.

Kind regards

Mike

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Hi Troy,

I expect you'll get a lot of responses to this one. The other thing to consider in looking at stalls & spins is spiral dives (which are often confused with spins).

There's some great reading on the RA-Aus website which covers all of this, check it out: http://www.auf.asn.au/groundschool/umodule8.html.

Cheers,

Matt

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Hi Troy,

You'll find oodles of videos of stalls and spins on YouTube, one of my favourites is this one (

) as you get to see it from the outside.Cheers,

Tony

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The spin can be good fun when done in an aerobatic plane and was a required part of the training when I learnt to fly. Beware of the spiral dive which is in my opinion much more dangerous. If you fly in cloud and get disorientated you usually get into a spiral dive and in that state you have an out of balance plane, the ball is over to one side and the altimeter is unwinding. This usually means that you pull back on the stick to reduce the descent rate but in fact it just steepens the turn, resulting in more "G' pulled. The end comes when the wings fall off if you are really unlucky. I have been there years ago in instrument training and the instructor asked me where I was and when I didn't know she flipped up the hood and the horizon was at a very steep angle disappearing above the wing of the C172. It taught me what I didn't know, but I still hear pilots say they can fly in cloud safely even if they have no IFR instruments or training.

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By John S. Denken

This is what I found very illustrative and important:

".......One fine spring day I was instructing a student who had about 5 hours experience. This was her first lesson in SLOW flight, but she was doing really well: she was maintaining the assigned altitude, the assigned heading, and the assigned airspeed (a couple of knots above the stalling speed). She was also doing a good job of keeping the inclinometer ball in the center, which required considerable pressure on the right rudder pedal because of the high power and low airspeed. I was really enjoying the flight, but suddenly I developed a feeling that there was something wrong. Gradually it dawned on me what the problem was. The problem was that the airplane was upside down.

Here’s what had happened: her right foot had gotten tired, so she JUST REMOVED it from the pedal — all at once. This produced a sudden yaw to the left. Naturally the left wing dropped, so she applied full right aileron. The nose was dropping, too, so she pulled back sharply on the yoke. The next thing anybody knew, we were upside down.

I took the controls and rolled the plane right-side-up. (See section 16.21 for more about this.) We lost about 500 feet of altitude during the maneuver. The student asked “What was THAT?” and I said “That was a pretty nice snap roll”.

This is indeed the recipe for a snap roll: starting from a speed slightly above the stall, apply a sudden yaw with the rudder, apply opposite aileron, and pull back on the yoke. SNAP! — One wing stalls and the plane rolls over. In our case, we didn’t roll exactly 180 degrees — “only” about 135 degrees — but that’s upside down enough for most people. It took a fraction of a second......."

Good reading, hey....?

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this is great thanks everyone.......the youtube video realy helps confirm it (yah youtube) anyway thanks to all that imput to this thread i will keep following it for more info Troy

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Spins/spirals/flicks.

Tony, what is the reference to an inclinometer? The understanding I have of that instrument is that it is a simple pendulous device that will give an approximation of pitch attitude in unaccellerated flight. The DH 82 had a glass tube with coloured fluid in it, in the shape of a triangle ,when viewed from the side. They must be refering to the SKID ball.The flick is a horizontal spin ( one way of looking at it . Nev

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I think Mr. John S. Denken is an american and a scientist.

To me he is referring to a normal ball.

What I found PARTICULARY important in this example is if my FOOT SLIPS I am in danger to go into a spiral dive after that 'snap roll'.

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I think Mr. John S. Denken is an american and a scientist.To me he is referring to a normal ball.

What I found PARTICULARY important in this example is if my FOOT SLIPS I am in danger to go into a spiral dive after that 'snap roll'.

G'day Tony,

That's a good site www.av8n.com

I think that it's better to worry about other things than that. :) Firstly a spiral dive is not really on the cards in that situation. A spiral dive is a nose down turning dive with increasing speed and g. It is not going to turn into a snap roll or a flick roll. It is A Very Bad Thing if not controlled.

A flick roll is as has been said elsewhere a form of horizontal spin.

If I had to take away any message from all of this stuff it would be:

1. For each aircraft type you fly you should understand the slow flight regime and be aware of the aerodynamic warnings of impending stall. Go to 3500' and fly the a/c slowly. Stall it, stall it with flaps (if it has them), with power on and with power off. Watch the a/c behaviour, understand what you are feeling through the controls. Fly the aircraft whilst nibbling at the stall and understand how the controls feel and how the aircraft performs. You need to understand instinctively what it is that you are feeling when, potentially at high workload, you approach the stall. Without a stall spins, flicks and other associated delights can't occur;

2. Always fly balanced. Make sure that the little black ball is where it should be - the only time it should be non-centred is when you are deliberately cross controlled. In that circumstance you need to be very aware of staying away from the critical AOA. If you always fly balanced the a/c performs better anyway;

3. Understand and practice the stall recovery procedure so that it becomes automatic. When you are in a stalled or nearly stalled situation you need to respond instinctively to the warnings and recover with minimum loss of height.

Do that and all is well. Flicks and spins are not part of our operating envelope. Understand how to operate in a flight envelope that avoids the likelihood of getting into that kind of situation.

Regards

Mike

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Thanks Mike,

Good to read it. So far I have only 14 hours on Thruster T500, so it is all in front of me. One thing is still missing in my circuits - the ROUNDING of this taildragger in my final steep approach at 50 Kts. I can fly it just fine to the point of rounding and there my instructor takes over.

To narrow the question: WHEN to start rounding and how while doing a steep approach.

My instructor encourages me to take over at the and of skimming after he touches down, so I am not missing that taildragger speed fun on ground, I actually do enjoy it. But that rounding and consequent skimming is still missing in my inputs.

Tony

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Tony, I don't know if this will help you, but I find trying not to land can work - holding off.

Disperse, here are some links to have a look at spins from the inside.

normal spin

flat spin

accelerated spin

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Landing Thruster.

Tony,

If you are seriously into analysing all this relating to thrusters, may I suggest that you avail yourself of some of the material from Tony Hayes. TOSG Central on this forum. Nev...

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Hey Troy, chill out from all the theory. Check out these spins......lots of fun, even if I do say so myself ;)

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Spins.

There's a related video there. "10 turn spin in a Super Decathlon ".Gives you an internal/ external view of it , Actual video.. You will see that it has nothing to do with a Spiral . Nev

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