MichaelP wrote:
You didn't ask me about buying one of these!
There were only so many things one could ask in limited time. I probably only had a chance to learn like 5% of the diamond questions I had anyway. Learning and knowledge take time, I have not found a way around this yet unfortunately. Thank you for your insights back then Michael.
Regarding the video, I'm surprised nobody noticed that on most of those recoveries, the pilot pushed the stick forward before applying opposite rudder. Obviously gets it done in this airplane, but bad technique in general. Some airplanes can get some rudder blanking going on if you push the stick forward before applying rudder, not to mention accelerating the spin as well if the rudder gets blanked and doesn't immediately stop the rotation. The recovery steps written out at the beginning of the video were right. The pilot didn't quite follow them as written, though.
Yeah, low-wing aircraft often use a scary amount of forward stick, early on, for spin recovery. Try that in a high wing or a biplane, and you're in for a wild ride.
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Last edited by Hedley on Mon Jan 24, 2011 3:35 pm, edited 1 time in total.
Don't know if it has anything to do with the T-tail, but the DA-20 is really easy to stop spinning. Neutralizing the rudder and pushing the stick forward alone unstalls the wing and it recovers has been my experience. The proper throttle back, rudder on the ball and stick forward (well before the rotation stops) unstalls it within the prescribed one turn. Too much stick forward just ends you up in completely noze down attitude when rotation stops. What do I know though
All Spencer does is relax the aft stick during a vanilla
upright spin, and watch the yaw rate.
Enthusiastic stick use can also result in a crossover spin,
which I doubt you really want to do accidentally. Most
people find it a wee bit confusing, which generally isn't
good for minimum altitude recovery.
Yes, you are right about the forward pressure and accelerated spin. I did experience that releasing the pressure on the stick made the plane rotate faster, it was actually fun. Because I did not know it was a special kind of a spin, I followed the same procedure of applying the opposite rudder. It did recover immediately. Now I understand that the proper way was to pull the stick back again to full deflection and then apply the opposite rudder. Thank you, will remember this.
I explain the increased rotation prior to spin recovery in this way.
We all know how lift increases with angle of attack until the wing reaches the critical angle beyond which a further increase of that angle causes a reduction of lift (stall).
Take it the other way.
Start with a wing with an angle of attack of 90 degrees... There's no lift! But at 80 degrees there's a little, 70 a bit more, 60, 50, 40, 30 degrees, all the time the lift is increasing.
As the wing approaches the critical angle from a higher angle of attack the amount of lift increases rapidly.
It's geometric and not linear.
If we believe that one wing is stalled more than the other in a spin then the less stalled wing's increase in lift is more rapid than the more stalled wing as the angle of attack is reduced.
So from a fully developed spin the less stalled wing's lift ratio increases relative to the more stalled wing until they both reach the same angle of attack when the rotation has stopped.
The increase in the difference of the lift between the less stalled and more stalled wing during recovery accounts for the increase in rotation speed as the aircraft recovers prior to the complete stop of rotation.
Three recoveries in the Katana:
1. Stick forward pause then opposite rudder.
An increase in rotation rate followed by a delayed recovery. Add a quarter to one turn or more.
2. Opposite rudder pause stick forward (standard)
Less increase in rotation rate (resisted by the rudder), minimum height loss, < 1 turn.
3. Opposite rudder at the same time as stick forward
No appreciable difference to #2
A friend of mine shocked himself with the increased rotation in the Citabria when he eased the stick forward during the spin with full rudder applied.
But,
We do this all the time when we do a flick roll (snap roll) when after initiating the manoeuvre with full aft stick and full rudder (and sometimes opposite aileron, erect flick!) the stick is centred and the roll rate increases.
We try to use abrupt anti spin control (opposite rudder at the same time as stick forward) to stop the flick where we want it... 'Takes a bit of practice to get it right.
In addition to reduced AOA there is also reduced radius of gyration. Think of what happens when a figure skater is spinning in one place, and pulls her arms and legs in. Same thing as the aircraft going more vertical - mass is centralizing.
We do this all the time when we do a flick roll (snap roll) when after initiating the manoeuvre with full aft stick and full rudder (and sometimes opposite aileron, erect flick!) the stick is centred and the roll rate increases.
We try to use abrupt anti spin control (opposite rudder at the same time as stick forward) to stop the flick where we want it... 'Takes a bit of practice to get it right.
You are understating it .. it takes a hell of a lot of practice to get it right ... well it took me a hell of a lot of practice and every winter I forget about 30% of it and have to relearn in the spring.
We do this all the time when we do a flick roll (snap roll) when after initiating the manoeuvre with full aft stick and full rudder (and sometimes opposite aileron, erect flick!) the stick is centred and the roll rate increases.
We try to use abrupt anti spin control (opposite rudder at the same time as stick forward) to stop the flick where we want it... 'Takes a bit of practice to get it right.
You are understating it .. it takes a hell of a lot of practice to get it right ... well it took me a hell of a lot of practice and every winter I forget about 30% of it and have to relearn in the spring.
I thought all the practice was in how to cheat with using the ailerons to get a perfectly flat recovery in a way that doesn't show
... well it took me a hell of a lot of practice and every winter I forget about 30% of it and have to relearn in the spring.
Sometimes I type too fast. My bad.