I spotted this video posted elsewhere.
It’s a Panthera aircraft being spun (intentionally).
What I found interesting was that the attitude of the aircraft was very stable during the spin. It’s was always point down at roughly 60 degrees. This is shown from various angles on the aircraft.
However if you look at the EFIS you’ll see that it shows all sorts of rolls and inverted flight which never actually happens. I presume the same happens with analogue AIs (I remember being told that they were unreliable in a spin and shouldn’t be used in a spin).
I just thought it an interesting demonstration of how the AI could give you very misleading clues if you ever found yourself in a spin in IMC!
Poor frame rate? camera related? It could also be filtering being set too high for aerobatics. Mechanical gyros is normally locked during aerobatics. The small one in the middle seems to be working OK though. But it sure looks confusing.
Well, some work better than others. With these, it’s matter of software. I saw this a long time ago and how differently behaved the backup AI (it looks like an RC Allen unit, which is certified) and the PFD was interesting.
Good video, interesting that it achieves autorotation quite smoothly, but am I correct the pilot is holding in spin ailerons, implying there is pronounced washout on the wing? Also appears slightly more fuselage loaded than other GA types, hence a steeper pitch attitude?
Recovery appears to be pitch to unstall, the T-tail is not blanking the rudder, aileron and rudder. Not the P-A-R-E or Mueller technique.
In a spin to the right the propeller (right turning), would steepen the spin in theory, and with some forward CG, might potentially lead to a cross over into inverted if you lead recovery with pitch (too aggressively), then the T tail might be blanking the rudder.
Getting the spin recovery technique from the AFM would be useful.
Only a turn and bank will show spin rotation, not sure an AI can cope, and a turn co ordinator is unreliable in showing spin direction.
RobertL18C wrote:
Only a turn and bank will show spin rotation, not sure an AI can cope
It should, at least the ones with solid state gyro and accelerometer. I think it depends on other stuff as well. The attitude is correlated with the GPS to minimize drift, and that correlation is probably bananas in a spin. The backup AH is has no correlation? and shows correct attitude.
LeSving wrote:
t should, at least the ones with solid state gyro and accelerometer. I think it depends on other stuff as well. The attitude is correlated with the GPS to minimize drift, and that correlation is probably bananas in a spin. The backup AH is has no correlation? and shows correct attitude.
An EFIS such as the G1000 doesn’t have a turn indicator, but it has a heading trend indicator. In normal flight there is no practical difference, but would it show the correct yaw direction in a spin? I guess it would not in an inverted spin at least.
RobertL18C wrote:
Good video, interesting that it achieves autorotation quite smoothly, but am I correct the pilot is holding in spin ailerons, implying there is pronounced washout on the wing? Also appears slightly more fuselage loaded than other GA types, hence a steeper pitch attitude?Recovery appears to be pitch to unstall, the T-tail is not blanking the rudder, aileron and rudder. Not the P-A-R-E or Mueller technique.
I thought so too, but the second sequence from the outside makes the inputs a bit clearer
– he initiates with a sharp pull-back and left rudder
– ailerons are neutral throughout the spin (or slightly pro-spin, difficult to see)
– full pro-spin rudder is held throughout
– recovery is full anti-spin rudder, followed almost immediately by NEUTRAL elevator (or slight nose down input) (even before the rotation stops)
– also, on the inside video – he puts the stick roughly in the position where it later is for the level flight after recovery
… and in recovery, he almost gets 90 degrees nose down pitch – so if he had pushed a bit [more], he would have ended up slightly inverted…
I have spun several G1000 and one G500 equipped aircraft, and those systems seem to manage just fine. I won’t say they would be perfect for a recovery reference, but I have no recollection of their being way off either. It is rare for common GA artificial horizon instruments to be cagable. I have only once flown in an aircraft in which caging was even possible. Any “modern” AI I have flown could be toppled in a spin, but was not damaged. They are more likely damaged from being caged, when the caging mechanism actually tries to prevent the free motion of the gyroscope. The toppling of the AI is mostly related to the acute nose down attitude which can be achieved during recovery.
The attitude achieved during recovery can be type dependent, and very certainly C of G dependent. During spin testing I flew in an modified Cessna Caravan, the forward C of G spins were near vertical dive recovery (which is more favourable), while the aft C of G recoveries were alarming, in that getting the nose much below the horizon was difficult. It is often the spin recovery characteristics which determine the aft C of G limit for an aircraft – which is why it’s wise to fly within C of G limits! I have had a Cessna 206 go more than vertical for a moment during spin recovery.
Pilot_DAR wrote:
It is often the spin recovery characteristics which determine the aft C of G limit for an aircraft – which is why it’s wise to fly within C of G limits!
This would mean it is common to lose aircraft during spin testing, before establishing the rear CoG limit?
Isn’t a safety margin ahead of the neutral longitudinal stability point, that determines aft C of G?
Without a variable incidence tail plane (ie most GA aircraft except some bush planes like the Super Cub and Cessna 180/185 and the 182C), the elevator loses some effectiveness through the trim tab as C of G moves towards limits. Having said this the 180/185/182 is not approved for spins, and the Super Cub utility C of G limits are such, that practically they are only approved for spinning with only the pilot in the front seat, no student and half fuel.
One spin pre flight check, especially on old training hacks as the average forty year old, non virgin, 152, is to check for control cable play at full down elevator, not sure many schools do that. If there is play the elevator will trail in the not fully down position. Fortunately the 152 is so spin resistant that actually getting it into stable autorotation is an effort, however, like most spin resistant aircraft, once in a properly developed spin some of them can take several turns to recover – contrary to the impression given that it will normally recover by letting go of the controls. But as virtually no one actually gets them into the stable autorotation stage, their spin recovery appears quite benign.
