Spit IIa

[Crumpp]

The best way to asses the Spit instability for everyone here and its uncomfortable 3/4 inch (2cm) stick travel would be to reconfigure your joystick to allow only that travel in the pitch zone.

Remember, size does matter......



A good simulation of the Spitfire will have the aircraft twitchy or skittish and hard to precisely control in the longitudinal axis. The higher the angle of attack, the more skittish the aircraft; the lower the angle of attack, the more stable the longitudinal axis. It will take skill and constant attention to maintain a set altitude and will require small precise stick inputs to keep it from overloading the airframe on dive recovery or reaching an accelerated stall in a turn. If it does experience an accelerated stall, the stall is extremely harsh and will require immediate application of the correct control inputs ( reduce the angle of attack and increase airspeed) to keep from spinning.

It will take about 2000 feet to stop the spin and then the pilot will have recover the aircraft to flight. The correct inputs are full rudder in the opposite direction until the spin is fully recovered; Stick neutral and then slowly brought forward. The nose will come down and the rotation speed will increase until enough dynamic pressure is built for the control to be effective and stop the rotation. The aircraft will be nose down in a dive which the pilot then recovers from. The book recommends 5,000 to 6,000 foot margin to ensure a recovery from an accidental spin. Deliberate spins are prohibited because the airframe can fail under certain conditions in a spin.

Remember that the Spitfire had poor control force harmony as well. The lateral control forces have a much steeper gradient than the longitudinal. That means the aileron forces increase much faster than the elevator forces. While your elevator is very light in control forces with only a 3/4 inch travel from cruise to stall point, the ailerons require much more force to induce a given roll rate. As the Operating Instructions relate, it would require the pilot to brace his elbow in order to apply the heavy aileron force required to reach maximum deflection while being careful not to induce any elevator input.

[TomcatViP]

Originally Posted by Crumpp

Remember, size does matter......



A good simulation of the Spitfire will have the aircraft twitchy or skittish and hard to precisely control in the longitudinal axis. The higher the angle of attack, the more skittish the aircraft; the lower the angle of attack, the more stable the longitudinal axis. It will take skill and constant attention to maintain a set altitude and will require small precise stick inputs to keep it from overloading the airframe on dive recovery or reaching an accelerated stall in a turn. If it does experience an accelerated stall, the stall is extremely harsh and will require immediate application of the correct control inputs ( reduce the angle of attack and increase airspeed) to keep from spinning.

It will take about 2000 feet to stop the spin and then the pilot will have recover the aircraft to flight. The correct inputs are full rudder in the opposite direction until the spin is fully recovered; Stick neutral and then slowly brought forward. The nose will come down and the rotation speed will increase until enough dynamic pressure is built for the control to be effective and stop the rotation. The aircraft will be nose down in a dive which the pilot then recovers from. The book recommends 5,000 to 6,000 foot margin to ensure a recovery from an accidental spin. Deliberate spins are prohibited because the airframe can fail under certain conditions in a spin.

Remember that the Spitfire had poor control force harmony as well. The lateral control forces have a much steeper gradient than the longitudinal. That means the aileron forces increase much faster than the elevator forces. While your elevator is very light in control forces with only a 3/4 inch travel from cruise to stall point, the ailerons require much more force to induce a given roll rate. As the Operating Instructions relate, it would require the pilot to brace his elbow in order to apply the heavy aileron force required to reach maximum deflection while being careful not to induce any elevator input.

All is said there.

But the 3/4inch value need to be assessed one more time. We can't only rely on a single NACA report. Even if NACA/NASA docs are among the most reliable sources available on the web.

If we put things back in the contest, at the time of the evaluation the US fighter industry was struggling to produce a viable pony capable to compete with Eu models.

[Crumpp]

If we put things back in the contest, at the time of the evaluation the US fighter industry was struggling to produce a viable pony capable to compete with Eu models.

Certainly.

Stability and control is one area the United States was ahead of other Allied Nations.

The United States pioneered stability and control research. It was the first to quantify the science.

In fact, both the Germans and the Japanese standards were based on Warner, Norton, and Allen's work at MIT as well as Gilruth's work at the NACA.

In 1942, an RAE engineer named Sydney B Gates made his famous (in stability and control engineering circles only, lol ) "dash around America" comparing NACA research to RAE at the time. It was primarily thru Gates efforts that the RAE eventually did adopt a standard but his efforts did not reach fruition until post war. That standard mirrored the NACA's standard.

[Skoshi Tiger]

Originally Posted by Crumpp

Remember, size does matter......



A good simulation of the Spitfire will have the aircraft twitchy or skittish and hard to precisely control in the longitudinal axis. The higher the angle of attack, the more skittish the aircraft; the lower the angle of attack, the more stable the longitudinal axis. It will take skill and constant attention to maintain a set altitude and will require small precise stick inputs to keep it from overloading the airframe on dive recovery or reaching an accelerated stall in a turn. If it does experience an accelerated stall, the stall is extremely harsh and will require immediate application of the correct control inputs ( reduce the angle of attack and increase airspeed) to keep from spinning.

It will take about 2000 feet to stop the spin and then the pilot will have recover the aircraft to flight. The correct inputs are full rudder in the opposite direction until the spin is fully recovered; Stick neutral and then slowly brought forward. The nose will come down and the rotation speed will increase until enough dynamic pressure is built for the control to be effective and stop the rotation. The aircraft will be nose down in a dive which the pilot then recovers from. The book recommends 5,000 to 6,000 foot margin to ensure a recovery from an accidental spin. Deliberate spins are prohibited because the airframe can fail under certain conditions in a spin.

That sound just like was happening with me at Hawkinge about 10 minutes ago. 2000 foot recovery sounds about right. Recovery fairly conventional as you describe. CoD must be a good sim.

[Crumpp]

2000 foot recovery sounds about right.

To stop the spin or to recover?

[Skoshi Tiger]

Originally Posted by Crumpp

To stop the spin or to recover?

For the plane to stop spinning and I jammed on the throttle. Though I don't profess to be an expert, I'm sure that would be a lot of better pilots around.

I'll have a go at recording a track and see how the numbers stack up on the guages.

Cheers!

[Skoshi Tiger]

Originally Posted by Skoshi Tiger

For the plane to stop spinning and I jammed on the throttle. Though I don't profess to be an expert, I'm sure that would be a lot of better pilots around.

I'll have a go at recording a track and see how the numbers stack up on the guages.

Cheers!

No end of problem trying to get a video, crashes etc wen trying to use fraps with playing a track..

Tried a few spins in a MkIIa (I remembered was in the Mk1a in the online mission I mentioned before)

With the MkIIa in a power on spin (2600rpm, full throttle pull the stick back until it spins) I was taking about 1000 feet to stop the autorotation, and around the 1500 feet before I got to the 150mph speed before recovering as stated in manual page in this thread.

This is less than the 2000 foot required to recover as quoted by you Crumpp.

The flick into the spin is very brutal and the plane is unstable at the high angle of attack required to enter the spin.

Will try the same with a conventional spin entry when I get some time.

Cheers!

[Crumpp]

Ok, sounds good.