Spit IIa

[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.