Spins

[CARLOS RANGEL]

Hello forum!
How much affect, the mass distribution and wing planform of the airplane during the spins?
The Beggs Muller method and P.A.R.E method, work only for a propeller airplanes?
What about swept wing aircraft, like a jet fighter the spin recovery procedure is different?

Saludos

Carlos

[pransbury]

Hi Carlos,

Sorry for the late reply on this posting. Believe it or not, I'm actually getting away for vacation tomorrow for about 10 days so will need to keep this response relatively short simply due to time available.

It is important to emphasize that once you get out of normal/aerobatic category single engine, general aviation, light aircraft genre the design consideration of any amount of spin recoverability is non-existent in reference to a 'number of turns' of protection as an example. Specifically, multi-engine airplanes, as well as business jets and transport category airplanes, do not have any design features by certification that offer the operator any amount of recoverability from a developed spin. The GA Normal Category SE certification of '1-turn or 3 seconds, whichever is longer' does not apply any more despite many many many pilots believing it does. Generally speaking, the only spin-resistance consideration during certification for these large/ME aircraft is for them to not demonstrate any 'undue tendency to spin' during stall recovery testing. Simply put, there is no guarantee that any non-GA light SE Normal Category aircraft is going to be recoverable from any sustained Stall+Yaw flight condition.

It is critical for pilots of all category and types of aircraft not to allow an aircraft to sustain a stalled flight condition for any amount of time longer than it takes for the pilot to immediately respond with a reduction of angle of attack to below critical.

To your question on mass distribution, light SE GA aircraft tend to have relatively uniform distribution of mass between the fuselage and wing components generally giving these aircraft relatively steady-state spin characteristics. When you begin to assess the recoverability of fuselage-heavy aircraft (fighters for example) or wing-heavy aircraft (ie. any multi-engine wing-mounted aircraft) then the inertia of rotation of these localized masses in a spin can quickly put the airplane into an inertially locked spin mode. What I mean by inertially locked is that the pilot is unable, through the manipulation of controls and configuration, to generate sufficient anti-spin force to overcome the inertia of rotation. In such a case, even if the pilot knew exactly how to recover from a spin in that aircraft type earlier in the spin development, once the spin has been allowed to develop further, the aircraft will likely be unrecoverable no matter what the pilot does in the cockpit. As for fighters, many of them have some type of spin recovery published in there operating instructions and they ALL have a mandatory bailout altitude if it doesn't recover. For example, in the F/A-18 many of our pilots flew at APS, the spin recovery was simply to remove all inputs from the controls, wait for the system to display big arrows indicating the direction to move the ailerons (ie. in-spin) and wait while the computers optimized the control positions to maximize recoverability .... either the jet would recover or it wouldn't. If it wouldn't then it would be returned to the taxpayer at mandatory bailout altitude (so to speak).

Here is a article that discusses some important information related to spin recovery that you may find interesting:

Spin Recovery Training

Gotta run and I'm sorry for the brief reply. Please post any follow-up questions as I know this answer is somewhat vague in relation to your question.

[CARLOS RANGEL]

Hi BJ,

Talking about NASA Standard Spin Recovery ( P.A.R.E )
Power ( off )
Ailerons ( Neutral )
Rudder (Full opposite )
Elevator ( Push the elevator through neutral ,upright spin mode)

Rudder
elevator

Deflecting the aileron into the spin, Is it possible to use this input to produce an anti-spin force ( adverse yaw ) to help the rudder during the recovery??

Saludos

Carlos