Parlous State of Spin Knowledge and Training

[facthunter]

Anyhow if you get in a spin at circuit height you probably won't recover it in the height you have available. My experience of U/L instructing  at the end of my flying  is that the majority of students are $#!t scared of stalling which some may think of as a good thing but I don't, IF it's going to happen by accident or any significant likelihood of it.. Unfortunately even people with immense experience can stall a Wirraway on final. fatally. So what's the answer.?  Nev

Edited February 22 by facthunter
more content.

[RFguy]

Factory handling notes for the PA28 suggest not immediately jumping on the opposite rudder with a wing drop on a stall , just centralize the controls, power off if necessary......as   unnecessary use of full rudder may invite an 'undesirable aircraft state' ...   in the simulator , in a rather unhelpful pro-trouble aircraft configuration, I got a rollover and inverted half ?spin? to commence.... let go of everything, nose down dive and recovery.

Edited February 22 by RFguy

[RFguy]

but i might have bent the airframe on the recovery... hard in the sim to grasp everything.

Edited February 22 by RFguy

[facthunter]

You won't feel the "G" but with the choice of a plane that has one it should show what you pulled.  Nev

[djpacro]

22 hours ago, LoonyBob said:

The FAA flight test guide rests largely on RAeS/ARL and German data from pre-WW2; again, the FAA FTG is not a comprehensive first-principles study, but a guide for flight testing.

 

It is just this failure to distinguish between an incipient and full spin, that eroded the original Certification requirement to recover from a developed spin.

Not altogether, there's a wealth of information from NASA's GA spin research around the '70s which contributed significantly. 

 

I don't know what you mean about eroding "the original certification requirement"? 

I see some significant differences between CAR3 and FAR23 (the versions that applied to many aircraft around today). The latest FAR 23 is different again.

 

I'll have a look for that older spin material, thanks.

[Jabiru7252]

Back in the late 70s industry said 'give us a plane we can spin and stall' for flying training. Piper came up with the Tomahawk and Beechcraft with the Skipper. These planes are hard to tell apart. I did stalls, spins and spiral dives in the Tomahawk and one day I read that a Tomahawk lost its tail during a spin and so no more spinning the things. I have never really liked 'T' tails - they always look flimsy to me.

Edited February 23 by Jabiru7252

[facthunter]

"T" tails have very high Loads compared to a conventional tail,  Nev

[skippydiesel]

1 hour ago, facthunter said:

"T" tails have very high Loads compared to a conventional tail,  Nev

Please explain?? 

[skippydiesel]

T tails must be more than just a fashion statement - everything from gliders to big commercial jets have them. My last aircraft had one - seemed to me, to perform flawlessly.

[facthunter]

AS a good example the B 727 vertical fin had 5 FIVE times the strain anticipated by the design engineers when flight tested with Strain Gauges  on it, Many DC9's had the rear door and bulkhead removed and replaced as it was fatigued in high time planes. .The Piper Tomahawk is not a roaring success

 Rear engined JETS HAVE to have T tails. You just have  to ensure they are strong enough for the Job.  Nev

[Reynard]

The Traumahawk had a reputation for ‘wagging’ its tail which resulted in an AD to inspect the vertical fin attachment plate for cracks. 

[skippydiesel]

So Nev - my  interpretation of the above-:

 

The "Loads" are the same (T /low /cruciform) its how they are applied that differs.

 

In a low/cruciform (mid) horizontal stabiliser mounting position the loads on the stabiliser are transmitted to the fuselage tail cone. 

 

The tail cone being an inherently strong/stiff structure, relatively, to the vertical stabiliser/fin.

 

The T tails must have a more robust/larger vertical tail/fin structure, compared to the above, to accommodate the leverage exerted by the horizontal stabiliser - principle of moments/leverage.

 

Its likely the forces acting on the T tail vertical stabiliser, require more complex design construction than for a conventional lay out.

 

Clearly there are pros/cons to the T tail concept however they must confer significant advantage in certain designs, beyond the obvious jet engine application.

 

Seems to me that the T tail has an undeserved bad reputation, as the result of failures in certain aircraft, where the concept was poorly executed/constructed.

[facthunter]

Beefing up anything requires extra mass and you still have aeroelasticity if the structure is thin sectioned and not braced/strutted Get a structural Harmonic and the wing is gone. Example Lockheed Electra It wasn't engine vibration it was due to the thrust line changing when the engine mounts sagged.  Nev

[facthunter]

The BF 109 Had strutted tailfeathers. It must have needed it.  The B 707 wing tip would flex a distance of 27 feet without  permanent deformation.   Nev

[Roundsounds]

I would be interested to hear people’s thoughts in regards to the following quote…

 

“in a slipping turn you are providing anti spin rudder. In a skidding turn pro spin rudder.”

 

[Area-51]

2 hours ago, Roundsounds said:

I would be interested to hear people’s thoughts in regards to the following quote…

 

“in a slipping turn you are providing anti spin rudder. In a skidding turn pro spin rudder.”

 

That sounds perilously misleading

[facthunter]

Why do you think that?    Nev

[Blueadventures]

On 24/02/2024 at 8:28 AM, facthunter said:

"T" tails have very high Loads compared to a conventional tail,  Nev

A comparison example would be the Piper Arrow and I hear the conventional horizontal stabiliser setup is a better aircraft to fly than the 'T' tail version.  I have only flown in a "T" so unable to compare from experience just what I have heard.

[facthunter]

I don't think the average pilot would notice much difference.  Nev

[facthunter]

Getting back to Roundsounds question. In a slipping turn you have plenty of Bank and stop the nose dropping with TOP rudder (against the turn). In  a skidding turn you don't have enough bank for turn rate you want and you apply more rudder in the direction you are turning to make it turn faster but in a pro spin configuration.  Nev

[Area-51]

2 hours ago, facthunter said:

Why do you think that?    Nev

There's no such thing as "pro" or "anti" spin rudder in the above situation; when the contributing factor of elevator limit is crossed the aircraft will spin in what ever direction, toward which ever is the first wing tip to stall. It's either going to spin to the left or the right, before turning upright or inverted and autorotate. Until the aircraft starts entering to the time of exiting can there be termed "pro" or "anti" spin rudder; and it should be termed "positive" or "negative" spin rudder because using too much "anti" spin rudder is probably just going to send the untrained spinning again in the opposite way. To apply this terminology while in a slipping or skidding turn gives the untrained pilot a false sense of security that as long as they apply "anti" spin rudder they will be arriving home for tea that evening.... (its not going to work like "antilock braking")... If that is what is being presented in the training syllabus it would explain a lot of now dead pilots.

[facthunter]

The pilot CONTROLS the direction  of spin always if they know what they are doing by RUDDER..  Nev

[facthunter]

GEEZ nearly an hour and NO response??   Nev

[Area-51]

3 hours ago, facthunter said:

The pilot CONTROLS the direction  of spin always if they know what they are doing by RUDDER..  Nev

True

[LoonyBob]

On 23/02/2024 at 10:58 AM, djpacro said:

Not altogether, there's a wealth of information from NASA's GA spin research around the '70s which contributed significantly. 

 

I don't know what you mean about eroding "the original certification requirement"? 

I see some significant differences between CAR3 and FAR23 (the versions that applied to many aircraft around today). The latest FAR 23 is different again.

 

I'll have a look for that older spin material, thanks.

The Certification flight testing used to involve three turns of a developed spin; then it became three rotations after dropping a wing... the DCA started to have arguments with the FAA back in the '60s, according to my sources... I think NZ also had a disagreement on the topic.