Tail Rotor vs Twin Rotor (ie Chinook)
TT, you’ve been talking to some knowledgeable old heads, I think. The guy who finished checking me out in our 21 had recently returned from VN and taught that technique of gaining additional climb performance by swinging the rear rotor out to the side and away from the forward rotor’s downward flow field when taking off toward a tree line. One time and you get the idea.
You’re also on point re the SAS-off directional stability. We would practice that quite a bit, and it paid off one day when, returning from a trip out to Ft Bliss, the upper seal in the aft transmission failed in a quick, major league way, and the transmission lubricant came pouring down over the both AC generators in the back of that box, shorting both out, and along with it both SAS. The ship started out sideways very quickly indeed: blew in one window on the side that yawed into the wind.
You’re also on point re the SAS-off directional stability. We would practice that quite a bit, and it paid off one day when, returning from a trip out to Ft Bliss, the upper seal in the aft transmission failed in a quick, major league way, and the transmission lubricant came pouring down over the both AC generators in the back of that box, shorting both out, and along with it both SAS. The ship started out sideways very quickly indeed: blew in one window on the side that yawed into the wind.
Once upon a time, I talked to some of the Bell test pilots and engineers who worked on the HSL program, an early 1950s tandem powered by a P&W R-2800 engine for ASW. When I said HSL, their next sentence included the words “noise” and/or “vibration”. It was quite a learning curve for them, but the joint experience that resulted from solving all its problems forged them into the team that created the HU-1 (not a typo, nephews; that’s why its nickname is Huey).
the two tandems in the US military inventory history, the CH-21 and CH-47
Oops-you are correct SAS. Actually the guy I sat next to immediately upon joining SA, Rip Green, had flown the 25, and did not have much good to say about it, but I do not remember what his complaints were. Unfortunately, Rip left not too long after I signed in. But the 25 didn’t last very long at all in Army livery now that I recall. So, while it didn’t impress, the 21 did, and there were still healthy casual bar discussions involving whether it, or the H-34 was a better machine in the mid 60’s.
Last edited by JohnDixson; 10th Nov 2018 at 00:52. Reason: typo
Well, then there was the predecessor to the Mule, the HRP-1. 20 delivered between late 1947 and 1949, initially used by the Marine Corps (pay attention SASless) for developing vertical assault tactics, then passed on to the Coast Guard for SAR development. The remaining (attrition rate?) then went to the USN for dipping sonar and minesweeping development: talk about cutting edge!
OK, not US Army but still the lead in service machine to the H-25
And it was his great-uncle Gustav Piasecki Eiffel who also played with metal frameworks, and his nephew John Piasecki Bradfield did the Sydney Harbour Bridge. Another descendant created the Big Banana at Coffs Harbour, but it never took off...
Avoid imitations
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Thread Starter
Thanks for your inputs
Thankyou ladies and gentlemen for your insights. I guess I hadn’t really thought about it too much but I understand the role of the gear box on helicopters now.
So a tail rotor should keep spinning with the main rotor even in the result of an engine(s) failure allowing auto rotation. I guess both sets of blades will keep spinning on the Chinook allowing for the same.
A TR failure or blade collision on a Chinook are both clearly dramatic emergencies. One more so than the other depending on circumstances (apart from being on the ground I can’t really imagine a blade collision ever being surviveable).
So really cost is the main reason we don’t see more twin blade (I apologise if this is not the correct term) designs.
Again, thanks for your inputs. I think I’ll still avoid helicopters whenever possible though. They’re just not right.
BV😁
So a tail rotor should keep spinning with the main rotor even in the result of an engine(s) failure allowing auto rotation. I guess both sets of blades will keep spinning on the Chinook allowing for the same.
A TR failure or blade collision on a Chinook are both clearly dramatic emergencies. One more so than the other depending on circumstances (apart from being on the ground I can’t really imagine a blade collision ever being surviveable).
So really cost is the main reason we don’t see more twin blade (I apologise if this is not the correct term) designs.
Again, thanks for your inputs. I think I’ll still avoid helicopters whenever possible though. They’re just not right.
BV😁
Again, thanks for your inputs. I think I’ll still avoid helicopters whenever possible though. They’re just not right.
Bob, I really think you are a secret admirer of the helicopter fraternity,and should really get yourself on a cross-dresser...sorry,cross-over course at Valley...Enough of the mundane,flashing around you`ve done with your arse on fire,come and join the gang that really get down`n dirty...With your `ex-steely `good looks,golden locks and blue eyes ,you`d be an immediate `hit` with the `blue-rinse brigade`,stepping out of a camo or yellow helo at an airshow..Come on,you know it makes sense at your age...get on that skateboard,and seek new challenges.....!!
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Bob Viking
If your fixed wing ever drops you in the sea, you may be glad of a Helicopter being around.
I have to correct thread 23, the Belvedere was made by Bristol, not Westland. It has a bad reputation, not always justified. If you consider it was the late fifties, and you had a machine that had an AUW of 22,000 Lbs, could maintain altitude on one engine, had a cruise speed of 120 Knots, and a VNE of 140 Knots, (from Memory).
The starter system was high maintenance, but did work ok most of the time. Its an urban myth that some pilots tried to start the aircraft from outside of the cockpit as they were frightened of the starter, that would not be possible, as the rotor brake had to be off to start the aircraft. I flew several hundred hours as a crewman, and I never saw a pilot do this.
I only had one starter explosion on my time, and that was a low key event, I was in the left hand seat when the pilot pressed the button, there was a muted thump from the rear engine, and then the fire warning came on, we exited in an orderly fashion.
The main rotor heads were similar to the Sycamore, and were light weight, and low maintenance.
If you are interested, seek out a Belvedere in a museum, note the flush skin panels, the Shobert riveting, and the doors and window hatches that worked correctly, the build standard was better than either Westland, or Sikorsky could attain.
In my time as a Helicopter Engineer, I flew in about Nine Helicopter types, as Crewman, Flight Test Engineer, or passenger, and I can say that the Belvedere was the smoothest.
If your fixed wing ever drops you in the sea, you may be glad of a Helicopter being around.
I have to correct thread 23, the Belvedere was made by Bristol, not Westland. It has a bad reputation, not always justified. If you consider it was the late fifties, and you had a machine that had an AUW of 22,000 Lbs, could maintain altitude on one engine, had a cruise speed of 120 Knots, and a VNE of 140 Knots, (from Memory).
The starter system was high maintenance, but did work ok most of the time. Its an urban myth that some pilots tried to start the aircraft from outside of the cockpit as they were frightened of the starter, that would not be possible, as the rotor brake had to be off to start the aircraft. I flew several hundred hours as a crewman, and I never saw a pilot do this.
I only had one starter explosion on my time, and that was a low key event, I was in the left hand seat when the pilot pressed the button, there was a muted thump from the rear engine, and then the fire warning came on, we exited in an orderly fashion.
The main rotor heads were similar to the Sycamore, and were light weight, and low maintenance.
If you are interested, seek out a Belvedere in a museum, note the flush skin panels, the Shobert riveting, and the doors and window hatches that worked correctly, the build standard was better than either Westland, or Sikorsky could attain.
In my time as a Helicopter Engineer, I flew in about Nine Helicopter types, as Crewman, Flight Test Engineer, or passenger, and I can say that the Belvedere was the smoothest.
Thread Starter
sycamore
That is a very kind offer. I shall give it some thought.
For now though I have a joke for you. It’s not exactly politically correct but it’ll serve a purpose.
Whats the worst thing about being a rollerblader?
Having to tell your parents you’re gay.
Now of course, you could substitute rollerblader for all manner of things.
BV
For now though I have a joke for you. It’s not exactly politically correct but it’ll serve a purpose.
Whats the worst thing about being a rollerblader?
Having to tell your parents you’re gay.
Now of course, you could substitute rollerblader for all manner of things.
BV
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B V
Remember though autorotation can still be achieved with tail rotor not spinning!
So a tail rotor should keep spinning with the main rotor even in the result of an engine(s) failure allowing auto rotation.
Bob....ease up!
My whole Helicopter career my dear Mum always thought I played Piano in a Brothel......I never told her otherwise for fear the truth would kill the old girl!
My whole Helicopter career my dear Mum always thought I played Piano in a Brothel......I never told her otherwise for fear the truth would kill the old girl!
Dear Bob – you are very clearly of the fixed plank mindset – and that is fine – but I think we would all agree that birds are the finest flyers on the planet and most of them do zero speed landings from Eagles to Tits. (Calm down). You may also have noticed that the wings of birds are made up of hundreds and hundreds of moving parts that all seem to hinge in harmony to achieve both forward flight and all the uppy downy bits in between. I seem to recall that plank wings that you favour have all the sophistication of a slab of balsa with traily bits stuck on the rear.(Calm down sailor).
I will agree that the hundreds and hundreds of bits in a helicopter hardly seem to work in harmony but most of the time whatever they do is fine by me if it keeps me airborne. The less you know about how it works is a huge stress reliever!
I will agree that the hundreds and hundreds of bits in a helicopter hardly seem to work in harmony but most of the time whatever they do is fine by me if it keeps me airborne. The less you know about how it works is a huge stress reliever!
Thread Starter
Birds vs helicopters
I think your criteria for lumping birds in with helicopters is a little tenuous to say the least.
I have yet to see a bird with a giant spinning feather arrangement on his bonce. They have wings like an aeroplane. Admittedly they flap them which, thankfully, does not occur (often) on fixed wing aircraft.
The choice of birds to stop before landing is surely related to their lack of wheels and has nothing to do with a desire to look like a helicopter.
Maybe evolution could solve the wheels problem given another few million years.
BV
I have yet to see a bird with a giant spinning feather arrangement on his bonce. They have wings like an aeroplane. Admittedly they flap them which, thankfully, does not occur (often) on fixed wing aircraft.
The choice of birds to stop before landing is surely related to their lack of wheels and has nothing to do with a desire to look like a helicopter.
Maybe evolution could solve the wheels problem given another few million years.
BV
Come on, Bob, we all know that an aeroplane is designed to fly, and it is only the drongo pilot who interferes with the controls that makes it crash.
A helicopter is designed to crash, and it is only the brilliant, good-looking, articulate pilot who stops it from doing so by the delicate and deliberate manipulation of the controls, to make it look totally effortless.
And rescue the drongo plank pilot who crashed.
A helicopter is designed to crash, and it is only the brilliant, good-looking, articulate pilot who stops it from doing so by the delicate and deliberate manipulation of the controls, to make it look totally effortless.
And rescue the drongo plank pilot who crashed.