24. THE LOSS OF THE GREEN HORNET

Every helicopter in existence must establish a Height/Velocity Diagram. It is probably the most dangerous part of a flight test program.  A number of aircraft have been lost and we were no exception. We used  to joke about this program because it is like trying to adjust the automatic release of a ski in case of a fall.  Keep tightening the release until you break your ankle then back off a half a turn and that’s it.

In the case of a single engine helicopter it’s a matter of establishing when you can successfully land the aircraft after an engine failure.  First from a hover, when the engine fails you are coming down, obviously, but how far can you fall using your rotor RPM to cushion your contact with the ground without damage.  Finding that point is the objective.

Doing the same thing at various airspeeds/altitudes, remember, that at some point auto-rotation is possible. All these points will vary with gross weight, temperature, elevation and wind. The same thing for twin engine except you are only required to do the test with one engine failure.

The end result is a diagram showing altitude and airspeed with a curved area in red indicating where you should not fly. A normal flight pattern would be lift off, hover 10-15 ft., proceed at that altitude to about 50 knots and climb out. 

The Green  Hornet was a company owned V-107 being used for FAA Certification. The Height/Velocity testing was being done at the Philadelphia Navy Base airport because so many landings and take-offs were required it was difficult at Philadelphia Airport with all the traffic

The aircraft was instrumented  so that when the test got to the dangerous point it could be cut off. The pilots were Vertol’s Phil Camerano and an FAA pilot whose name escapes me. One day of  tests were completed and were started the next day. On one of the landings the aircraft hit hard and collapsed the left main landing gear, dropping the stub wing/fuel tank to the ground, and caught fire. 

The Navy crash crew had been standing by in case something like this happened.  The crash crew’s normal procedure was to approach a fire up wind, which they did, unfortunately the fire was on the other side of the aircraft and their foam did no good.  As a result we lost the aircraft.  Some of us flew over in another aircraft.  It was a mess.

When we all arrived back at Flight Test there was a message for all Flight Test Engineering personnel to report to the Director of Engineering’s office immediately. That would be Norm Taylor.  We all arrived and were seated in his conference  room when he came in and announced that we all were fired.  He instructed us each to write him a letter and explain what part we played in this program, and a second letter explaining why he should  rehire us. 

When they took another look at the data from the previous day, it was evident that if they continued to the next test points a failure would occur. I think a couple of engineers were off for a few days, but all were rehired.