Chinook & other tandem rotors discussions
Iconoclast
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
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In response.
To: NickLappos
The following is taken from the CH-47D Airframe Drive/Rotor Systems H7-U-10-1
Volume 2 (Customer Training Manual published by Boeing Helicopters) (page 6-24).
FLIGHT CONTROLS
PITCH INPUT FORWARD
When the pilot moves the cyclic stick forward the 1st stage mixing unit will extend the output control of the aft head, and retract the output control to the forward head. This extension and retraction is called differential thrust between heads or differential collective pitch. The second stage mixing unit will extend the two outputs to the aft rotor system, and retract the outputs to the forward rotor system.
There is no aft cyclic input. Forward cyclic input is made by the retraction of the electric actuators attached to the forward and aft swashplates when the helicopter reaches around 60 knots. When the helicopter slows down below 60 knots the actuators extend removing forward cyclic input. Lateral cyclic is available at all times.
TO: SASless: Thanks for the correction however the movement of the cyclic stick fore and aft does not effect the fore and aft rotors cyclically it effects them collectively. This input either raises or lowers the swashplates it does not tilt them. Due to the design of the swashplates and their connection to the electric actuator there may be a very slight cyclic input but this is not intentionally input by the pilot.
The following is taken from the CH-47D Airframe Drive/Rotor Systems H7-U-10-1
Volume 2 (Customer Training Manual published by Boeing Helicopters) (page 6-24).
FLIGHT CONTROLS
PITCH INPUT FORWARD
When the pilot moves the cyclic stick forward the 1st stage mixing unit will extend the output control of the aft head, and retract the output control to the forward head. This extension and retraction is called differential thrust between heads or differential collective pitch. The second stage mixing unit will extend the two outputs to the aft rotor system, and retract the outputs to the forward rotor system.
There is no aft cyclic input. Forward cyclic input is made by the retraction of the electric actuators attached to the forward and aft swashplates when the helicopter reaches around 60 knots. When the helicopter slows down below 60 knots the actuators extend removing forward cyclic input. Lateral cyclic is available at all times.
TO: SASless: Thanks for the correction however the movement of the cyclic stick fore and aft does not effect the fore and aft rotors cyclically it effects them collectively. This input either raises or lowers the swashplates it does not tilt them. Due to the design of the swashplates and their connection to the electric actuator there may be a very slight cyclic input but this is not intentionally input by the pilot.
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After some great years flying the CH47 I have my annual company check tomorrow and I must say I am dreading (as ever) the scarry tail rotor failures I will have to do just for fun!! When will the rest of the world realise that tail rotors are just not cool!! I long to be flying with foot rests again, not moving foot pedals!!
Also miss not taking my car with me where ever I go.
Also miss not taking my car with me where ever I go.
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To clear up any confusion, the chinook transitions by applying more or less lift to the rear rotor. This can only be done 1 way collectively. When it gets to a point the pilot would then have to pull back slightly to maintain the transition at higher speeds without hitting the ground. To stop this the aircraft is fitted with DASH (Digital Airspeed Hold) This keep the floor level and stops the pilot having to make unconventional corrections.
Lu,
Lets clear up some of your misunderstanding of what you read.
Early on in this thread....I corrected one of your posts by clearly stating the concept was "differential collective pitch....DCP". You come late with that excerpt from the manual or what ever you are reading from.
You mix two systems up here...the normal hydraulic controlled and operated flight controls and the electrically operated Speed Trim System.
Lu, if you switch the Speed Trims off.....they do not operate....the speed trim system is inoperative...the aircraft is Vne limited...greatly limited. But Lu, the hydraulic flight controls continue working normally.
Two independent systems Lu....nothing to do with each other at all.
Lu...where do you come up with the idea that anyone said the two rotor heads moved cyclically in movements of the cyclic stick in a fore and aft direction. Are you not the one that stated "the pilot cannot input forward cyclic"?
Also Lu, when the speed trims function...there is no coorelation to Thrust Lever position....any reduction, if any of Thrust Lever position,is not noticeable and since the speed trim actuators are moving as the aircraft is accelerating...the only Thrust Lever reduction would be as a triming effort by the pilot to achieve a desired airspeed/altitude combination. Thrust Lever Lu is the correct nomenclature for the "collective lever" .
I know the Chinook is a bit more complicated than a Robinson...and according to several posters you had some problems with that rotorhead....but Lu....read and quote from all of the pertinent sections of the manual if you are going to do so. Be thorough in your submissions.
Lets clear up some of your misunderstanding of what you read.
Early on in this thread....I corrected one of your posts by clearly stating the concept was "differential collective pitch....DCP". You come late with that excerpt from the manual or what ever you are reading from.
You mix two systems up here...the normal hydraulic controlled and operated flight controls and the electrically operated Speed Trim System.
Lu, if you switch the Speed Trims off.....they do not operate....the speed trim system is inoperative...the aircraft is Vne limited...greatly limited. But Lu, the hydraulic flight controls continue working normally.
Two independent systems Lu....nothing to do with each other at all.
Lu...where do you come up with the idea that anyone said the two rotor heads moved cyclically in movements of the cyclic stick in a fore and aft direction. Are you not the one that stated "the pilot cannot input forward cyclic"?
Also Lu, when the speed trims function...there is no coorelation to Thrust Lever position....any reduction, if any of Thrust Lever position,is not noticeable and since the speed trim actuators are moving as the aircraft is accelerating...the only Thrust Lever reduction would be as a triming effort by the pilot to achieve a desired airspeed/altitude combination. Thrust Lever Lu is the correct nomenclature for the "collective lever" .
I know the Chinook is a bit more complicated than a Robinson...and according to several posters you had some problems with that rotorhead....but Lu....read and quote from all of the pertinent sections of the manual if you are going to do so. Be thorough in your submissions.
Last edited by SASless; 18th Jan 2005 at 12:37.
Mr Toad,
I take it you used to fly with BAH?
My father, a/c engineer, worked on BA's BV234s, and was never overly enthusiastic about the machine.
He once took me out to Longside airfield, to see one of them, which had diverted following engine problems. I got to spend a couple of hours looking over this fascinating machine - a pretty magical experience for a 10 year old. Can't quite believe it was 20 odd years ago though.
I remember the time a BV234 did a small flight display at the yearly fete at RAF Buchan. During a climbing spot turn (I don't know the correct term for the manoeuvre), they managed to quite literally blow away the cricket team in the adjoining playing field. I met the pilot in question a number of years later, when he was re-telling the story in the crewroom at Longside.
There is a BV234 related story that I've been told a number of times, when Max Bailey (sp?) and crew did a medivac from the East Shetland Basin with two critically injured person's, one of whom sadly passed away. I've never known if it was a semi-urban legend, but it was claimed that the machine they used was never quite the same afterwards, whether it was due to the effort of the crew to get to ABZ asap or what.
Does anyone know if Max Bailey is still around?
I take it you used to fly with BAH?
My father, a/c engineer, worked on BA's BV234s, and was never overly enthusiastic about the machine.
He once took me out to Longside airfield, to see one of them, which had diverted following engine problems. I got to spend a couple of hours looking over this fascinating machine - a pretty magical experience for a 10 year old. Can't quite believe it was 20 odd years ago though.
I remember the time a BV234 did a small flight display at the yearly fete at RAF Buchan. During a climbing spot turn (I don't know the correct term for the manoeuvre), they managed to quite literally blow away the cricket team in the adjoining playing field. I met the pilot in question a number of years later, when he was re-telling the story in the crewroom at Longside.
There is a BV234 related story that I've been told a number of times, when Max Bailey (sp?) and crew did a medivac from the East Shetland Basin with two critically injured person's, one of whom sadly passed away. I've never known if it was a semi-urban legend, but it was claimed that the machine they used was never quite the same afterwards, whether it was due to the effort of the crew to get to ABZ asap or what.
Does anyone know if Max Bailey is still around?
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Chinook Ground Resonance
There was a link to a video clip of a Chinook beating itself to death due ground resonance posted in a thread in the past.
Ive done a search but couldnt find it, anybody knows where it is?
thanks
Ive done a search but couldnt find it, anybody knows where it is?
thanks
Guest
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http://www.chinook-helicopter.com/hi.../84-24156.html
One quick google search for Chinook Ground Resonance.
This link gives you the rear and side video which the other link only gave you the rear view.
Awsome enjoy, humbling video.
One quick google search for Chinook Ground Resonance.
This link gives you the rear and side video which the other link only gave you the rear view.
Awsome enjoy, humbling video.
Worth noting that aircraft is tied down, and in a very non-standard way.
Yes, it's GR, but don't think your Chinook is going to do that to ya. You'll need to abuse her heavily first!
Yes, it's GR, but don't think your Chinook is going to do that to ya. You'll need to abuse her heavily first!
I read somewhere they were preparing for shooting the old girl to determine its resistance to hits by various weapons but never quite got to the scheduled tests due to the minor problem encountered as evidenced by the video.
Was there not a thread on this before?
Was there not a thread on this before?
Iconoclast
Join Date: Sep 2000
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Ground Resonnnnnnnance????
I went on the web site and was only able to download the rear view. The video lasted about 5 seconds and I saw no evidence of ground resonance. Did I do something wrong?
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I saw a video on Discovery Ch. once, a Chinook landing on water, and a SOF team in a Zodiac or simmilar embarked via the rear ramp. Looked kinda cool!
But landing the thing in slat water must raise a lot of questions about corrosion?
But landing the thing in slat water must raise a lot of questions about corrosion?
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As an old chinook pilot during training way back in 1969, we received training in landing in the water and taxing around on a fresh water lake. The aircraft handled very well.
For a short while the RAF tried using a professional Educator, instead of aircrew, to carry out some of the Groundschool classroom teaching on the Chinook course. It didn't last - poor bloke tried to convince us that the water-dam was there to hold water inside the fuselage so's it could be used for water bombing...
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Aussie Chinook D Model reunion
Hi all,
I am organising the reunion of all persons involved in the re-introduction and operation of D Model Chinooks in the Australian Army. A piss up will be held in Townsville at 5 Avn Regt on 20 May and a more genteel cocktail party to include partners the following day at Kissing Point in Townsville. (It's just a name... not a requirement).
If you have any questions, please contact me, Conway Bown, at [email protected].
Also, if you're interested in aviation and military art, visit my website at www.ipas.com.au
Safe flying.
CB
I am organising the reunion of all persons involved in the re-introduction and operation of D Model Chinooks in the Australian Army. A piss up will be held in Townsville at 5 Avn Regt on 20 May and a more genteel cocktail party to include partners the following day at Kissing Point in Townsville. (It's just a name... not a requirement).
If you have any questions, please contact me, Conway Bown, at [email protected].
Also, if you're interested in aviation and military art, visit my website at www.ipas.com.au
Safe flying.
CB
As a proud owner of some of Boner's artwork, I can say that he is a very talented artist with a unique point of view. The gallery is well worth a look.
he can't fly for nuts, though.....
he can't fly for nuts, though.....
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woops - Tricycle Chinook
woops - Tricycle Chinook
What happened at Abingdon Chinook chappies?
Looked like a benign landing (1502L) followed by a departure to Odiham with three wheels, having lost back right somewhere!
Was Odiham the nearest suitable landing site from Abingdon?
Seriously though, good display until then and it did not appear to be a "heavy" landing.
What happened at Abingdon Chinook chappies?
Looked like a benign landing (1502L) followed by a departure to Odiham with three wheels, having lost back right somewhere!
Was Odiham the nearest suitable landing site from Abingdon?
Seriously though, good display until then and it did not appear to be a "heavy" landing.