Abid
AR-1 gyro manufacturer
- Joined
- Oct 31, 2011
- Messages
- 6,276
- Location
- Tampa, FL
- Aircraft
- AR-1
- Total Flight Time
- 4000+ 560 gyroplanes. Sport CFI Gyro and Trikes. Pilot Airplane
Center Line Thrust is always good and ideal because its the most efficient push you can give a body in the air.
But many things are not CLT in aviation. Tons.
The main issue is unloading the rotor and its common to both 2 bladed semi-rigid or teetering gyroplanes and helicopters like Robinsons, some Hillers, Heuy etc. are all susceptible to not having loading and they are powered rotors.
Cierva developed fully articulated rotors and was not using teetering 2 blade rotors (except some secret research of his autodynamic 2 blade rotors for jump takeoff). Its a point to note. It was not that he was CLT, had differential HS for torque. He did not have 2 bladed teetering rotor. Much more fundamental difference IMO.
I don't think that CLT competitors were peddling their ideas to make a quick buck Dennis. I think they truly were trying to make 2 blade gyroplanes safer to the best of their knowledge and ability. I do not doubt their intentions and in absence of a horizontal stab, CLT does make things better. No one questions that. Your gyro was without HS and was high thrust line and Glasgow University found your gyro stability similar to that of a certified 2 bladed heli. Except heli pilots train 80 hours on average with an established syllabus and testing requirements and gyro pilots cough at training 25 hours and in your days in the UK they trained 5 hours it seems. Well duh, what would one expect.
The study from Glasgow university claimed 4 things. Two of them were that presence of horizontal stabilizer is not a significant difference in long mode stability of the gyroplane and that the only thing that mattered was CLT (+ or - 2 inches of CG for thrust line). However in in-flight testing, their claim comes out to not stand completely correct in reference to horizontal stabilizer. Obviously this needs more work to reconcile but given that it took them 17 full years just to get to those conclusions is a bit depressing. Obviously capable but slow moving. May be the CAA funding was very slow to come and minor.
Certified Part 27 helicopters with teetering rotors do not have to prove all the things people are asking gyroplanes to prove. The bottom line with 2 bladed teetering rotors is that if you unload them you are going to be chopped meat. Helicopters or gyroplanes. They are not forgiving of such a mistake much. Having high thrust line at that point results usually in a PPO but that is a symptom. The problem is you have unloaded rotors and you have lost control of the aircraft already. The recovery is chopping power immediately and smoothly pulling back the stick just past neutral to gain rotor control back before making any roll correction
ON 7/27/83, MILD MAST BUMPING OCCURRED DURING A PUSHOVER MANEUVER WHILE A HILLER FH-1100 WAS ON A FLT TO CERTIFY NEW ROTOR BLADES. PRIOR TO THE INCIDENT, THE HELICOPTER WAS ACCELERATED TO 90 MPH. THIS WAS FOLLOWED BY A PULL-UP & DECELERATION TO 80 MPH, THEN THE PUSHOVER WAS INITIATED. THE HELICOPTER REPORTEDLY ROLLED SHARPLY TO THE RIGHT & PITCHEDNOSE DOWN WITH SOME YAW TO THE RIGHT. RECOVERY WAS MADE WITH LEFT CYCLIC; HOWEVER, DIRECTIONAL CONTROL WAS LOST BEFORE RECOVERY & MILD MAST BUMPING. ON 7/28/83, FH-1100, N450FH, A STANDARD PRODUCTION MODEL, WAS FLOWN TO EXPLORE THE PHENOMENON. AFTER 2 PUSHOVERS WITH INCREASING SEVERITY, IN WHICH CONTROL WAS RETAINED, THE PLT ATTEMPTED A REPETITION OF THE PREVIOUS DAY'S MANEUVER. WITNESSES OBSERVERVED THE HELICOPTER ROLL & YAW TO THE RIGHT & PITCH DOWN AS IT BEGAN TO BREAK UP, THEN BURN & CRASH. AN EXAM REVEALED THE MAIN ROTOR BLADES SEPARATED AFTER MAST BUMPING & MAST FAILURE OCCURRED. THERE WAS EVIDENCE THE PLT MIGHT NOT HAVE BEEN CURRENT IN TEETERING ROTOR SYSTEMS & RECOVERY FROM LOW G ROLLS.
But many things are not CLT in aviation. Tons.
The main issue is unloading the rotor and its common to both 2 bladed semi-rigid or teetering gyroplanes and helicopters like Robinsons, some Hillers, Heuy etc. are all susceptible to not having loading and they are powered rotors.
Cierva developed fully articulated rotors and was not using teetering 2 blade rotors (except some secret research of his autodynamic 2 blade rotors for jump takeoff). Its a point to note. It was not that he was CLT, had differential HS for torque. He did not have 2 bladed teetering rotor. Much more fundamental difference IMO.
I don't think that CLT competitors were peddling their ideas to make a quick buck Dennis. I think they truly were trying to make 2 blade gyroplanes safer to the best of their knowledge and ability. I do not doubt their intentions and in absence of a horizontal stab, CLT does make things better. No one questions that. Your gyro was without HS and was high thrust line and Glasgow University found your gyro stability similar to that of a certified 2 bladed heli. Except heli pilots train 80 hours on average with an established syllabus and testing requirements and gyro pilots cough at training 25 hours and in your days in the UK they trained 5 hours it seems. Well duh, what would one expect.
The study from Glasgow university claimed 4 things. Two of them were that presence of horizontal stabilizer is not a significant difference in long mode stability of the gyroplane and that the only thing that mattered was CLT (+ or - 2 inches of CG for thrust line). However in in-flight testing, their claim comes out to not stand completely correct in reference to horizontal stabilizer. Obviously this needs more work to reconcile but given that it took them 17 full years just to get to those conclusions is a bit depressing. Obviously capable but slow moving. May be the CAA funding was very slow to come and minor.
Certified Part 27 helicopters with teetering rotors do not have to prove all the things people are asking gyroplanes to prove. The bottom line with 2 bladed teetering rotors is that if you unload them you are going to be chopped meat. Helicopters or gyroplanes. They are not forgiving of such a mistake much. Having high thrust line at that point results usually in a PPO but that is a symptom. The problem is you have unloaded rotors and you have lost control of the aircraft already. The recovery is chopping power immediately and smoothly pulling back the stick just past neutral to gain rotor control back before making any roll correction
ON 7/27/83, MILD MAST BUMPING OCCURRED DURING A PUSHOVER MANEUVER WHILE A HILLER FH-1100 WAS ON A FLT TO CERTIFY NEW ROTOR BLADES. PRIOR TO THE INCIDENT, THE HELICOPTER WAS ACCELERATED TO 90 MPH. THIS WAS FOLLOWED BY A PULL-UP & DECELERATION TO 80 MPH, THEN THE PUSHOVER WAS INITIATED. THE HELICOPTER REPORTEDLY ROLLED SHARPLY TO THE RIGHT & PITCHEDNOSE DOWN WITH SOME YAW TO THE RIGHT. RECOVERY WAS MADE WITH LEFT CYCLIC; HOWEVER, DIRECTIONAL CONTROL WAS LOST BEFORE RECOVERY & MILD MAST BUMPING. ON 7/28/83, FH-1100, N450FH, A STANDARD PRODUCTION MODEL, WAS FLOWN TO EXPLORE THE PHENOMENON. AFTER 2 PUSHOVERS WITH INCREASING SEVERITY, IN WHICH CONTROL WAS RETAINED, THE PLT ATTEMPTED A REPETITION OF THE PREVIOUS DAY'S MANEUVER. WITNESSES OBSERVERVED THE HELICOPTER ROLL & YAW TO THE RIGHT & PITCH DOWN AS IT BEGAN TO BREAK UP, THEN BURN & CRASH. AN EXAM REVEALED THE MAIN ROTOR BLADES SEPARATED AFTER MAST BUMPING & MAST FAILURE OCCURRED. THERE WAS EVIDENCE THE PLT MIGHT NOT HAVE BEEN CURRENT IN TEETERING ROTOR SYSTEMS & RECOVERY FROM LOW G ROLLS.
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