old crash testing of wider chord rotor blade thread?

GrantR

Senior Member
Joined
Jul 16, 2007
Messages
1,329
Location
Plains, GA
Aircraft
Kolb MarkIII and a "Jake" Gyroplane
Total Flight Time
About 85 fixed wing 3 gyro
I have seen reference to a fatal crash involving the testing of wider chord dragon wing rotor blades. I can not find a link to this thread. I search the entire accident forum and didn’t see it. I wanted to read about it and see what cause the blades to fail. The only bits I remember are the Rotor blades had a larger chord maybe 8” and something happened causing the gyro to enter a dive and the pilot could not pull back on the stick.
 
What you are decribing is a merging of two different accidents involving those blades. Incorrect information Grant. If you would like the truth and not some hog wash spread by the ignorant call me 813-843-2833.
 
Will do Mike.
 
Won't be off till 7 Pm I will call you back after if you leave me a message. My AT&T cell phone doesn't work in this Verizon building. LOL
 
Mike,

Rather than explain what happened in a private phone conversation that only Grant will hear, why not post your side of the story here on the forum so we all can understand what happened.

Now, my curiosity is peaked and I want to know and I'll bet lots of others would too. I suppose you don't have the time to talk to everyone individually so posting it here on this thread makes a lot of sense to me.
 
Mike,

Rather than explain what happened in a private phone conversation that only Grant will hear, why not post your side of the story here on the forum so we all can understand what happened.

Now, my curiosity is peaked and I want to know and I'll bet lots of others would too. I suppose you don't have the time to talk to everyone individually so posting it here on this thread makes a lot of sense to me.

I take the opposite position. An open forum such as this this is NOT the place to discuss an incident of this nature. There were some rather complex issues involved, both human and mechanical. Considering the wide spectrum of personalities and levels of technical understanding here, it could serve no constructive purpose, only confusion.

Mike, I stand behind you in this. Anyone who would care to discuss it with me one on one, may call me at area code (787) 869-0692.
 
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I recall this crash, I believe it was ~11-12 years ago. At the time I was active on the old forum and I remember participating in the online conversation about the crash. From memory some guy (who's name escapes me) was flying a two place (I think a Parsons, but not sure) and experimenting with aluminum wide chord blades (as a way of carrying heavier payloads). He had flown the aircraft successfully by himself, but I believe it exhibited a slight reluctance to recover from a dive. The stick was heavy and had to pulled all the way back before it would respond and recover from a steep descent. At some point the "test pilot" landed and rather hurriedly grabbed what amounted to an innocent bystander (i.e. a person who did not really understand the risk he was taking by participating in test flights) and asked him to go for a ride (presumably to fully load the aircraft). They took off, gained a decent measure of altitude, started a turn (I think to the left?) and then were observed to go into a steep nose down descent. The descent was rapid and unabated until contact with the ground. I think the pilot was observed trying to pull back on the stick(?) during the fatal descent. The aircraft might have slightly corrected from the initial dive but then went in after that(?).

I recall myself and others speculating on possible causes (which an emphasis on speculate). Too much flexibility in the pitch axis and/or insufficient airfoil reflexion for the blade loading were possible suspects. Abrubt changes in pitching moments at the tips as a result of compressibility effects (i.e. mach tuck) were also discussed. I don't know what was determined afterwards by the people directly involved. It would be interesting to hear the story again and whatever came out of the whole thing.
 
Once again the two crashes are getting merged. The Air Command was Bill Parsons and he had an aluminum stick that was on 5 or 6 machines prior that were crashed. He considered it his lucky stick. Dad did not like the idea of an aluminum stick on a 1500 lb machine so while it was at the shop he made Bill a 4130 stick. When witnesses saw the machine in Bill's hangar it had the old stick back on it. The day of the accident he had moved some things around which resulted in it being out of CG. This is the reason for unstable flight that was reported not the blades. He was bragging to people who were there how well the new blades flew. He moved the battery and was seen putting his lucky stick in a vise and bending it so it would clear the battery in it's new location. He then test flew said it was fine. He then took a passenger for a ride who had no flight time. The witnesses said he was over the trees and went into a dive and never pulled out. They crashed into a stand of pine trees and were both ejected from the machine. Bill died instantly and his passenger a few days later. Dad was asked by the NTSB and FAA to help with the invetigation. He arrived a few hours after the accident and found the cause pretty quickly. The aluminum stick was on the machine and was broken. The aluminum was torn in the front where and tool marks were present from the jaws of the vise. The investigators determined that the stick broke in flight. Bill was trying to pull back but had no control in pitch. The passenger had no flight time so he did not grab the rear stick to save them. As for the blades on the Marchetti the exact same blades flew on another Machetti for over ten years until recently when a roll over accident destoyed them. Dad has a set he continues to fly on his two place today. He decided to not produce these blades because when something new is put on a gyro and an accident happens the new thing is automatically blamed. He decided the tooling costs were not worth producing them and only ten to twelve sets were ever made.
 
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Mike, you're right it was the accident with Jamie Bodie I was thinking of. The two crashes happened around the same time frame, sorry for the confusion. Reading the above reference brought it back. Too bad the original thread on the old forum is not available to read.
 
After Bill Parsons accident some other gyro manuf sent the following
Emergency Bulletin.

WARNING - WARNING - WARNING - WARNING - WARNING


This bulletin is recommended as an immediate correction to a potential flight safety problem concerning the joystick on two place ...........Gyroplanes. The aluminum joysticks should be removed and discarded, and a new joystick fabricated from 4130 steel tubing with a wall thickness of 0.058". The reason for this action is the heavier machines import heavier control system loads, and there is potential to exceed the safe life of aluminum 6061-T6 joysticks. A note should be entered in the aircraft records that this bulletin has been completed when the joystick is changed to 4130. Owners and operators not having access to 4130 steel tubing with a 0.058" wall, may order raw material or a finished replacement part from ........... Future production kits will incorporate this change.

Giorgos.
 
The reason the stick on Bills tandem failed, was because he tried to bend the stick forward while on the aircraft for more clearance, and put a slight kink in the metal. The people there when he did it told him to replace it, but he said it would be OK. A few flights later, it failed.
 
It was not an Air Command. It was a Parsons tandem Trainer, which is a stretched Bensen.

Dennis,
Did you ever see the machine he crashed? I did. It was an Air Command tandem not a Parsons. He may have re-used the N-numbers but it was most certainly a Mazda powered Air Command tandem. It was in my dad's shop a few days before that. Bill wanted to test fly the four bladed system that dad just built. Dad would not let Bill fly it until he built him a new stick. Bill did not like the four bladed system but eyed a set of the 8" blades on the rack and wanted to test fly them. We mounted and balanced a set, dad test flew them on his own machine, and then Bill flew them on his machine. Bill loved them and asked dad to let him test them some more and he would pay for them later.
 
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I think maybe a THIRD accident pattern is being mixed in here, too. There were some accidents in SxS Air Commands in Engalnd the late 80's. These were almost certainly PPOs, but the concept of PPO was locked inside just a few people's heads at the time.

The investigators (incorrectly, I think) blamed "pump handle" joysticks (those with a pitch pivot at the rear of the seat), among other things. The Florida owners of Air Command at the time came out with an "A.D." requiring a swap-out of the original aluminum pump-handle Air Command joystick for a Brock-style steel, walking-beam stick assembly designed (I believe) by Bill Parsons.

The PRA gyro design guidelines followed suit. For many years, they recommended avoiding pump sticks. They may still say that. It's a silly distraction from the real causes of PPO, which are mainly airframe and tail-feather layout.

As for aluminum sticks a la the original Air Command, I see nothing wrong with a properly-designed one on a light single-place gyro. Both Bensen's original overhead stick and his later, B-80 series joysticks, were built this way. I agree that one does not belong on a 1500 lb. machine unless the stick is much more heavily built that the typical 1" x.058-wall 6061-T6 tube used on light machines.

Back to topic: Some early Dragon Wings blades had just about no reflex (up-turned trailing edge) at all. Since their particular airfoil shape places the camber back from the leading edge compared to flat-bottomed foils, they have less need for reflex than the flat jobs. In most cases, the structural stiffness of the blades themselves is sufficent to resist twisting, even without any reflex.

The twisting moment is variable, though (it's a function of the square of the blade's airspeed, and that in turn is a function of both the gyro's own airspeed and RRPM). If the blades develop too much twisting moment on the advancing side (where their airspeed is the highest), the blades will de-pitch themselves in that sector of the rotor. The rotor's AOA will start to flatten out on its own. The effect is similar to hard forward stick -- a dive. That's likely what happened to Jamie Bodie and Sy Smith in the heavy Marchetti at Mentone.
 
Dennis,
He may have re-used the N-numbers but it was most certainly a Mazda powered Air Command tandem.

Hello Mike,

I am not familiar with the procedure for reusing an N number.

How does that work?

Was this crash in Dunnellon, Florida in 1985?

I was trying to identify it on the NTSB reports.

Thank you, Vance
 
Vance,
It's when someone crashes a gyro and the put the N-number on a new gyro and notates in their log book as engine change or something like that. This has been done by many, although not exactly legal. This crash was in 1997.It occured at Flagler County Airport near Daytona.
Doug,
I am not confusing Parson's accident with the accidents in England. I have a very good memory when it comes to this stuff. The 8" blades had a reflex in them. Once again the exact same blades were flown on Rick Martin's Marchetti for over ten years. They were wrecked recently during an accident in which Rick's student let the gyro get out of control and it rolled in to a canal after touchdown. My Dad is flying the same blades on his Subaru powered tandem and has had no problems. Don't you think these pitching problems you therorize about would have manfested themselves again?
 
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