Interesting thread.
During 1998 Atlantic Aeroengineering at Coventry modified a DC-3 as a Radar flying test bed for the new Racal (now Thales) radar for the RAF Nimrod. This involved fitting a very large radome under the nose of the DC-3 making the front of the aircraft very reminiscent of the back end of a dog.
This extensive modification naturally had implications for handling and performance and required the aircraft to be flight tested to restore its type rating. This testing included full stalling trials. In such circumstances, elderly aeroplanes have to meet not today’s airworthiness standards, but those that applied at the time of the type’s initial certification. In this case as spelled out in an FAA document of 1932 vintage.
While planning the trials I noted that the 1932 requirements required stalls to be carried out in the landing configuration at up to 75% power. When I talked to Atlantic’s training captain on the DC-3 he said they restricted power-on stalls to 40% or less to avoid very large wing and nose drops. He felt we could finish up inverted if we tried them at 75%. Accordingly given this sage advice (I had not flown a DC-3) I asked the CAA for an exemption from meeting the 1932 paperwork. They said we could put whatever limits on the trials that we wanted but they (naturally) would not necessarily certificate the aircraft based on such restricted trials.
Off we went and at 40% I found that at the stall there was a slight tendency to drop the left wing, limited to about 10 deg. We went on to do the 75% stalls with no wing drop but a slight un-commanded nose up tendency.
Why so? Simply because the aircraft was flown to reduce speed very slowly at not more than one knot per second, and no attempt was made to control the rate of climb or descent while this speed reduction was going on. The wheel was used to trickle back the IAS, so as soon as any symptom developed a slight check forward was all it took to take the wing away from the onset of the stalled condition and put a stop to whatever was going to happen.
Clearly such a technique produces very different results from just pulling back and holding level flight until something uncontrollable happens. Flying like that the speed reduction is likely to be quite rapid and so the wing will penetrate to an angle of attack way beyond the start of the stall before you have a chance to do anything.
Once the boundary of the first stall symptoms have been established, it may be acceptable to deliberately continue the backpressure on subsequent runs to progressively investigate the likely effects should somebody penetrate way beyond the first stall symptoms.
Bottom line – IMHO the DC-3 is no different from any other aircraft, if you charge into a stall you may get quite a surprise. Tickle it gently with some feel for what you are doing and it will talk to you with the odd twitch of the ailerons, a bit of buffet, a slight nose up movement (knock it off at once if you get one of those) or a nose drop, or a gradual tendency for the nose to move out to one side or combinations of such things, depending on power and configuration.
When we plotted my stall speed results, they were 2 knots faster that the book for the unmodified aircraft. I explained to Atlantic’s chief pilot that if he flew the aircraft using my technique he would doubtless get two knots slower than me because he was younger, knew the aircraft very well and was very current. And low it was thus and it came to pass that the CAA were happy.
Off topic, I favour the flight test stall technique for instructional purposes as well, at least with apprehensive and inexperienced students who can easily develop a real concern about stalling if pitched in to a fully developed stall right from the start