Which helicopter has the most peculiar flight characteristics?
Joined: Oct 2006
Posts: 5,174
Likes: 7
From: UK
It’s got to be the Sycamore, especially the HAR14 version. This was the basic training helicopter for the RAF until 1965 when they changed to the Sioux because they were crashing so many. It didn’t have a squash plate. The rotor was controlled (????) by a rod that went stuck out of the top of the rotor shaft and bent metal guided the blades. Skeeter and Scout similar, I believe.
It had wooden blades, not interchangeable, they came as a set. A replica of a 20mm cannon shell was the mass balance which stuck out of the tip. You couldn’t hover for very long. 23 inches MAP was the 30 min rating for the Leonides engine, 30 inches for 5 and you were at 27-28 all the time.
Control authority was chronic, No hydraulics, dual controls but only one collective so if you were in the left hand seat it was left hand for cyclic and right hand for collective. You had aeroplane type trim wheels to put Q force onto the stick and you had to anticipate it before a maneuver so that you did not have to re-trim it with you hands full. The collective/throttle cam for the engine was way out of sequence so when you lifted of you had to open the throttle and as you got airborne you had to roll it off. The hand throttle was horizontal like a motorbike but it went the wrong way. You rolled the top forward to increase and vice versa. Right hand seat you had you hand on top if the throttle, left hand seat you had your hand underneath it.
There was 62 pints of water meth in two tanks. One underneath the cabin and a smaller one in the pylon. When you started running out of fore or aft cyclic you pumped water from one end of the aircraft to the other.
Despite this it would cruise at 110 knots, trimmed out, hands off, in perfect comfort.
Practice engine offs were something else. You rolled back the engine, dumped the lever, pulled it up 2 notches, (a collective pitch indicator) set the engine to 1500rpm and went for you landing site, always an airfield. When you were certain you were going to reach it you pulled the throttle back and pulled the slow running cut out. (The 1500 rpm was to stabilize the cylinder head temps before shutdown) At about 100 ft you would fully flare and when it stopped you added another 2 notches and descended vertically. When the ground was just about to swallow you you wacked in all your collective and a bit of forward cyclic to get a couple of knots of groundspeed. You had to do this because at zero speed the undercarriage would splay and roll the tyres off the rims.
You then had to restart the engine. Droop stops on the Sycamore were horrendously unreliable and the blades would punch holes in the boom so you had to get the engine cranked up before the rotor RPM went critical. I never did an engine off during my training, the instructor had his hands on the controls all the time leading me.
Shutting down after a flight you had a mirror so you could check the soldiers (droop stops) on shutdown. Should one not go in than you rev the rotor up and down to persuade it. If that didn’t work you called out the fire crew.
One of them would kneel down with a big hose aiming it just over the top of the boom near the pylon. As you shut the engine down the blades would bounce off this jet of water and wouldn’t hit the boom. The blades had then had it. Being wooden and full of water they would warp and have to be replaced.
It was probably the best helicopter trainer ever used. If you could fly it you could fly anything.
Before any Knowall jumps on me saying they have seen a Sycamore with twin collectives etc there were versions produced with this but the HAR 14 was the standard RAF Sycamore.
It had wooden blades, not interchangeable, they came as a set. A replica of a 20mm cannon shell was the mass balance which stuck out of the tip. You couldn’t hover for very long. 23 inches MAP was the 30 min rating for the Leonides engine, 30 inches for 5 and you were at 27-28 all the time.
Control authority was chronic, No hydraulics, dual controls but only one collective so if you were in the left hand seat it was left hand for cyclic and right hand for collective. You had aeroplane type trim wheels to put Q force onto the stick and you had to anticipate it before a maneuver so that you did not have to re-trim it with you hands full. The collective/throttle cam for the engine was way out of sequence so when you lifted of you had to open the throttle and as you got airborne you had to roll it off. The hand throttle was horizontal like a motorbike but it went the wrong way. You rolled the top forward to increase and vice versa. Right hand seat you had you hand on top if the throttle, left hand seat you had your hand underneath it.
There was 62 pints of water meth in two tanks. One underneath the cabin and a smaller one in the pylon. When you started running out of fore or aft cyclic you pumped water from one end of the aircraft to the other.
Despite this it would cruise at 110 knots, trimmed out, hands off, in perfect comfort.
Practice engine offs were something else. You rolled back the engine, dumped the lever, pulled it up 2 notches, (a collective pitch indicator) set the engine to 1500rpm and went for you landing site, always an airfield. When you were certain you were going to reach it you pulled the throttle back and pulled the slow running cut out. (The 1500 rpm was to stabilize the cylinder head temps before shutdown) At about 100 ft you would fully flare and when it stopped you added another 2 notches and descended vertically. When the ground was just about to swallow you you wacked in all your collective and a bit of forward cyclic to get a couple of knots of groundspeed. You had to do this because at zero speed the undercarriage would splay and roll the tyres off the rims.
You then had to restart the engine. Droop stops on the Sycamore were horrendously unreliable and the blades would punch holes in the boom so you had to get the engine cranked up before the rotor RPM went critical. I never did an engine off during my training, the instructor had his hands on the controls all the time leading me.
Shutting down after a flight you had a mirror so you could check the soldiers (droop stops) on shutdown. Should one not go in than you rev the rotor up and down to persuade it. If that didn’t work you called out the fire crew.
One of them would kneel down with a big hose aiming it just over the top of the boom near the pylon. As you shut the engine down the blades would bounce off this jet of water and wouldn’t hit the boom. The blades had then had it. Being wooden and full of water they would warp and have to be replaced.
It was probably the best helicopter trainer ever used. If you could fly it you could fly anything.
Before any Knowall jumps on me saying they have seen a Sycamore with twin collectives etc there were versions produced with this but the HAR 14 was the standard RAF Sycamore.
Last edited by Fareastdriver; 2nd December 2007 at 14:11.
That's Life!!
Joined: Feb 2004
Posts: 396
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From: Out of the sand pit, carving a path through our jungle.
Collective bounce?
The S-61 had
The S-61 had
Joined: Dec 2006
Posts: 431
Likes: 41
From: yes
Ever land an Astar without the spring steel extensions touching?
>
Perhaps another thing to look at are - what are the strangest types of flying that you've heard of being done in a helicopter? For me, the two most interesting from a flying qualities point of view are:
<
Flying an ADS-33 course in an EC-120.
>
Perhaps another thing to look at are - what are the strangest types of flying that you've heard of being done in a helicopter? For me, the two most interesting from a flying qualities point of view are:
<
Flying an ADS-33 course in an EC-120.
Joined: Oct 2006
Posts: 5,174
Likes: 7
From: UK
Pumas rolling over after an EOL was due to the mechanical collective/yaw interconnect especially when close to zero speed. After the flare and whilst cushioning the collective would inpart a strong anti torque (Right pedal for Americans benefit) to the tail rotor that would be counterbalanced by the autopilot heading hold. When the alternators dropped off so did the autopilot so it yawed to the right.
The only way to counteract this was to banging on full left pedal this instant the alternators tripped. If you thought about it you were too late, if it had started yawing to the right you would never get it back but if you put too much on that was correctable.
I was shown how to and would demonstrate this in the mid 70s with two tanks in the back to ensure a proper needle split equivalent. Was not allowed to land it but without anticipators it would do the whole thing to a 3 foot sloppy hover with about 200 Rrpm.
THEN THE ENGINES WOULD WAKE UP.
On the yaw/roll divergence it was never noticed on pre polivalent aircraft. When we collected XW 209, the first one, we received concerned comments from Boscombe who were worried about it's aerodynamic stability with the increased area above the cockpit. We had other problems at the time so we didn't investigate it. The 332L has a forward plug in the fuselage and compared with an early 330 is is a pig to fly. The 332L has an extra fin forward of the skid to correct for the plug, maybe a Puma could do with the same.
The only way to counteract this was to banging on full left pedal this instant the alternators tripped. If you thought about it you were too late, if it had started yawing to the right you would never get it back but if you put too much on that was correctable.
I was shown how to and would demonstrate this in the mid 70s with two tanks in the back to ensure a proper needle split equivalent. Was not allowed to land it but without anticipators it would do the whole thing to a 3 foot sloppy hover with about 200 Rrpm.
THEN THE ENGINES WOULD WAKE UP.
On the yaw/roll divergence it was never noticed on pre polivalent aircraft. When we collected XW 209, the first one, we received concerned comments from Boscombe who were worried about it's aerodynamic stability with the increased area above the cockpit. We had other problems at the time so we didn't investigate it. The 332L has a forward plug in the fuselage and compared with an early 330 is is a pig to fly. The 332L has an extra fin forward of the skid to correct for the plug, maybe a Puma could do with the same.
Last edited by Fareastdriver; 3rd December 2007 at 01:44.
Joined: Dec 2001
Posts: 1,835
Likes: 3
From: Philadelphia PA
Although I only got 1.5 hrs on the Puma, and never did experience the roll/yaw divergence, one of my mates did on his ETPS preview, with an experienced Puma QHI. It happened when they rolled into a turn and added some pedal to keep the ball in the middle - surprised them all.
Evidently it only happens with a rear CG- lots of surface area ahead of / above the CG, and the pedal input added the necessary sideslip to cause the machine to roll pretty smartly.
That's why the later versions have the added area at the fin at the back.
Evidently it only happens with a rear CG- lots of surface area ahead of / above the CG, and the pedal input added the necessary sideslip to cause the machine to roll pretty smartly.
That's why the later versions have the added area at the fin at the back.
Joined: Aug 2000
Posts: 497
Likes: 31
From: A very long way North
The result was usually: pause two three WOO!! - the old girl would rapidly roll on a whole $#1t load more bank, all by herself. The student seldom asked for the demo to be repeated
Joined: Oct 2007
Posts: 147
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From: USA
Of all the things you guys talk about that can bite you in the ass with your various helos, I can think of more than one occasion in my limited 700 hours in the hawk that I've done the same thing or likewise ham-fisted and stupid, and she takes it in stride. Even flying around at max gross almost all the time, the 60 seems to have no bad habits at all. I'm inclined to think NickLappos really does know what he's talking about.....
Joined: Dec 2001
Posts: 1,835
Likes: 3
From: Philadelphia PA
The Blackhawk is proof positive that pilots care more about performance and power than handling qualities.
I don't know what's been changed in the newer versions, but the A model definitely had some unusual features -
Like a heading hold that required you to take your feet off the pedals.
A beeper trim system for the stick that was of no use (and no-one ever used it to change anything when the trim release worked much better).
Running out of collective in forward flight
Droop stops that couldn't stand a tailwind start up.
A tailwheel lock that could be nearly impossible to get in.
But performance wise - very nice. And having said some bad things about it, if I had to go to war in a utility helicopter, I'd want it to be a Blackhawk.
I don't know what's been changed in the newer versions, but the A model definitely had some unusual features -
Like a heading hold that required you to take your feet off the pedals.
A beeper trim system for the stick that was of no use (and no-one ever used it to change anything when the trim release worked much better).
Running out of collective in forward flight
Droop stops that couldn't stand a tailwind start up.
A tailwheel lock that could be nearly impossible to get in.
But performance wise - very nice. And having said some bad things about it, if I had to go to war in a utility helicopter, I'd want it to be a Blackhawk.
Joined: Dec 2006
Posts: 431
Likes: 41
From: yes
Why stop there?
1. Uncomfortable nose high hover attitude.
2. Limited forward/down cockpit visibility (which makes most new pilots fly approaches out of trim).
3. A stabilator that for years, scared the bejesus out of many pilots.
4. A rotor system that refuses to smooth (I swear somebody walked out of the plant with the master blade).
5. Transient rotor droop like a mother (A model).
6. It leaks like a sieve and the heater works intermittently at best.
But you can’t have mine.
1. Uncomfortable nose high hover attitude.
2. Limited forward/down cockpit visibility (which makes most new pilots fly approaches out of trim).
3. A stabilator that for years, scared the bejesus out of many pilots.
4. A rotor system that refuses to smooth (I swear somebody walked out of the plant with the master blade).
5. Transient rotor droop like a mother (A model).
6. It leaks like a sieve and the heater works intermittently at best.
But you can’t have mine.
Joined: Jul 2002
Posts: 221
Likes: 18
From: Somewhere, Over the Rainbow
100% agree on all the Blackhawk topics, except:
"A beeper trim system for the stick that was of no use (and no-one ever used it to change anything when the trim release worked much better)."
Our guys use that to good effect on instrument holding! Works far better than fighting the trim or releasing it alltogether. The new guys don't use the bleeper, but the old guys do, so it just adds more distance between the good old guys and the youngin's!
Mike
"A beeper trim system for the stick that was of no use (and no-one ever used it to change anything when the trim release worked much better)."
Our guys use that to good effect on instrument holding! Works far better than fighting the trim or releasing it alltogether. The new guys don't use the bleeper, but the old guys do, so it just adds more distance between the good old guys and the youngin's!
Mike
Thread Starter
Joined: Nov 2004
Posts: 1,334
Likes: 0
From: Cambridgeshire, UK
I'm learning a lot from all these posts! 
The Sycamore makes me appreciate how much development has gone into the R22, which seems to have no suprises (outside of what you would expect for such a nice simple machine). Has anyone ever considered the R22 as a trainer?
What causes the Puma to have it's WOO moment? Is this the beginnings of dutch roll, or is it just the amount of cyclic needed to hold it in the heading hold side slip?
I'm actually amazed the S-70 is not as vice proof as i thought. I'd like to hear more about how that stabilator, and the beeper trim, catches youngin's (and us wannabe's) out.
I'm sure i'll have many more questions - i'm just enjoying all the input..
The Sycamore makes me appreciate how much development has gone into the R22, which seems to have no suprises (outside of what you would expect for such a nice simple machine). Has anyone ever considered the R22 as a trainer?
What causes the Puma to have it's WOO moment? Is this the beginnings of dutch roll, or is it just the amount of cyclic needed to hold it in the heading hold side slip?
I'm actually amazed the S-70 is not as vice proof as i thought. I'd like to hear more about how that stabilator, and the beeper trim, catches youngin's (and us wannabe's) out.
I'm sure i'll have many more questions - i'm just enjoying all the input..
Joined: Oct 2006
Posts: 236
Likes: 0
From: cornwall UK
WG30
I flew about four hours on the Westland 30 back in the 80's- BAH had two or three of them. I was told, although I never had it confirmed, that as a throwback to the naval Lynx, the W30 had a collective input on cyclic so that when you pulled full power for a takeoff from the back of the frigate it made a rear cyclic input to ensure the aircraft didn't hit the frigate hangar. This input was evident throughout the speed range so that trying to get it to fly at the cruise speed for the day, typically 115 knots, meant endless trimming.
The engines had individual speed levers in the ceiling and, instead of a collective mounted beeper trim, a torque balancing control between them. Pulling to the hover almost always produced a large torque split which required taking your left hand from the collective, twisting the balance lever toward, as I remember it, the high engine, before grabbing the collective again. The SAS was a bag of nails involving 'half-lane switches' for each control axis which had to be activated in the event of a control malfunction. The height hold could not be used below 400 ft. Range with full pax was about 32nm.
On the plus side it had an enormous power reserve, an excellent gear box and a cabin section second, in those days, to none. The half dozen or so regular pilots swore by it and it performed very well operating the Penzance- Scillies service for a while.
Finally, I can remember a colleague converting unwillingly from the S61 to the first Puma's the company bought. "B-----y" thing, he said. "One day you pull collective and the nose goes up, the next day, you pull and it goes down!!"
The engines had individual speed levers in the ceiling and, instead of a collective mounted beeper trim, a torque balancing control between them. Pulling to the hover almost always produced a large torque split which required taking your left hand from the collective, twisting the balance lever toward, as I remember it, the high engine, before grabbing the collective again. The SAS was a bag of nails involving 'half-lane switches' for each control axis which had to be activated in the event of a control malfunction. The height hold could not be used below 400 ft. Range with full pax was about 32nm.
On the plus side it had an enormous power reserve, an excellent gear box and a cabin section second, in those days, to none. The half dozen or so regular pilots swore by it and it performed very well operating the Penzance- Scillies service for a while.
Finally, I can remember a colleague converting unwillingly from the S61 to the first Puma's the company bought. "B-----y" thing, he said. "One day you pull collective and the nose goes up, the next day, you pull and it goes down!!"
Last edited by Boslandew; 4th December 2007 at 12:45.
Joined: Oct 2006
Posts: 236
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From: cornwall UK
BV234
The commercial Chinook Flight Manual contained some very ambitious claims for operating speeds. At MAUW, rarely WAT limited, the book might say 130-135 knots. The aircraft vibrated a lot and each pilot seat and the entire 44 pax cabin were mounted on vibration absorbers, the left-hand seat being the worst for vibration.
With each flight from Aberdeen scheduled for 5-6 hours, on occasion 8.50hrs, one didn't wish to tarry so sought the maximum practical cruise. This meant accelerating once level using the 'cocked hat' until the co-pilot began to look blurred then reducing speed by a few knots until he came back into focus and stopped complaining produced the cruise speed, typically 115 knots.
With each flight from Aberdeen scheduled for 5-6 hours, on occasion 8.50hrs, one didn't wish to tarry so sought the maximum practical cruise. This meant accelerating once level using the 'cocked hat' until the co-pilot began to look blurred then reducing speed by a few knots until he came back into focus and stopped complaining produced the cruise speed, typically 115 knots.
Joined: Jul 2007
Posts: 7
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From: Berkshire
Laughed out loud at the Chinny cruise speed setting method. Of course the Hughes 300 is vastly superior to any of this mil tin-pannery - it cruises at a speed only fractionally lower than that at which it falls gracelessly out of the sky. Also is less accepting of rear-quartering breezes in the hover than Heather Mills of a divorce settlement. The thing will routinely throw the unwary into a right pirhouette with only a 3-5kt gust on take-off.
Joined: Jan 2006
Posts: 90
Likes: 2
From: USA
While Chinooks definitely vibrate, I find it odd that you were having as much as you decribed at those rather low cruise speeds - we used to cruise at 120-130 kts regularly in CH-47C & D models, and faster if in a hurry & light.
Didn't start getting annoying until 140+ kts in most with the current composite blades if a decent track & balance was done, the C models when they still had metal blades were even smoother.
Wonder what the differences were between the military & civilian models were that could account for that, or was it just poor track & balance?
Didn't start getting annoying until 140+ kts in most with the current composite blades if a decent track & balance was done, the C models when they still had metal blades were even smoother.
Wonder what the differences were between the military & civilian models were that could account for that, or was it just poor track & balance?
Joined: Jun 2002
Posts: 4
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From: Michigan
Common design feature
The Hughes 500 and the r22 also have the collective assist spring, because of the lack of hydraulics. Not a good idea to get out with the aircraft running in any of these aircraft.