FLYBOYJ
"THE GREAT GAZOO"
OK - Just got off the phone with my father in law - just for the record he was a production test pilot on the F-15, F-5 and was the chief production test pilot on the B-1B. he also did other flight test work at Edwards...
"Dad" told me that Inertial Coupling usually happens at higher mach numbers on aircraft with wingspans matching or smaller than the fuselage length. Jet aircraft could experience this at lower speeds if an extremely high roll rate was induced at a very high angle of attack - he pointed out the F-16 and Mirage could be made to experience this, with the Mirage being a bit more unforgiving. He did state that in his experience with a recip or propeller driven aircraft, this condition would certainly have to be induced especially at lower speeds and high AoA as engine torque tends to prevent this from happening. With that said, one could INDUCE Inertial Coupling on a recip aircraft at lower speeds (He pointed out that aerobatic performers do this all the time in Pitts).
In the case of uncommanded Inertial Coupling on a recip aircraft, he stated he doubts it would be a factor unless the aircraft is at a high altitude and is configured to do so (small wings, long fuselage).
I brought up the 190D and his feelings is the aircraft would have to be close to a high mach number (high altitude). He did ask "didn't that thing have guns in the wings?" When I told him yes he went on to say that the weight in the wings would probably help in preventing Interial Coupling, even if induced. His feelings were that even though the 190D had a short wingspan when compared to its fuselage, uncommanded Inertial coupling would be unlikely.
BTW - he said he doesn't recall hearing about any recip, propeller driven or WW2 aircraft with any Inertial Coupling tendency, in fact he confirmed, in the test pilot community Inertial coupling is thought of as a "Post WW2" thing. The first theoretical publication addressing Inertial Coupling wasn't published until 1948 (William Phillips of NACA).
"Dad" told me that Inertial Coupling usually happens at higher mach numbers on aircraft with wingspans matching or smaller than the fuselage length. Jet aircraft could experience this at lower speeds if an extremely high roll rate was induced at a very high angle of attack - he pointed out the F-16 and Mirage could be made to experience this, with the Mirage being a bit more unforgiving. He did state that in his experience with a recip or propeller driven aircraft, this condition would certainly have to be induced especially at lower speeds and high AoA as engine torque tends to prevent this from happening. With that said, one could INDUCE Inertial Coupling on a recip aircraft at lower speeds (He pointed out that aerobatic performers do this all the time in Pitts).
In the case of uncommanded Inertial Coupling on a recip aircraft, he stated he doubts it would be a factor unless the aircraft is at a high altitude and is configured to do so (small wings, long fuselage).
I brought up the 190D and his feelings is the aircraft would have to be close to a high mach number (high altitude). He did ask "didn't that thing have guns in the wings?" When I told him yes he went on to say that the weight in the wings would probably help in preventing Interial Coupling, even if induced. His feelings were that even though the 190D had a short wingspan when compared to its fuselage, uncommanded Inertial coupling would be unlikely.
BTW - he said he doesn't recall hearing about any recip, propeller driven or WW2 aircraft with any Inertial Coupling tendency, in fact he confirmed, in the test pilot community Inertial coupling is thought of as a "Post WW2" thing. The first theoretical publication addressing Inertial Coupling wasn't published until 1948 (William Phillips of NACA).
