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Rolling take offs in a Helicopter

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Rolling take offs in a Helicopter

Old 26th Jun 2021, 12:49
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We use these because of incredible dust. Much easier with wheels! Also prevents pelting the fixed wings with rocks when we lift into hover!
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Old 26th Jun 2021, 13:19
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If it won't even get off the ground with full up collective, you should be staying ON the ground.There are some exceptions, however, and it usually involves high speed pieces of lead proceeding in your specific direction
As I described earlier it was also a procedure used in order to get to the scene of high speed lead coming in your direction. One C model gunship landed to pick up the crew of an aircraft shot down which then made them too heavy to take off, by pulling some power they were able to yaw the aircraft in order to aim the mini guns at the opposition and give them a dose of high speed lead. Once the opposition was placated a slick landed to pick up the crew.
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Old 27th Jun 2021, 16:15
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Winnie,

What prevents you from segregating helicopter and fixed wing operations to provide a safe distance that would eliminate the throwing of rocks?

As dust is a shallow and short radius issue at takeoff....why not do a Towering Takeoff as done for ages in the past with no hovering....do a quick very low hover to ascertain all is right with the aircraft....land back....then take off from the ground and climb out of the dust cloud on Instruments?

If there is no question of the aircraft being ready to fly.....skip the low hover and just do the ITO.
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Old 28th Jun 2021, 11:03
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.the one question I would pose to that is if that "demand for more power" is a product of attempting to accelerate too quickly which would not matter if you were into wind or "down wind"....and as I recall Doctor Lappos correctly what he opined is the takeoff distance downwind is far greater than when done into wind and that if the control inputs are done properly there is no difference in the power required for the takeoff but rather just a much longer distance.
I'm sure he is correct - the amount of power required seems the same as long as you use the same technique both ways and are reasonably gentle on the controls.

What I have seen catch pilots out is being in the downwind hover with ETL from behind at close to max Tq then convincing themselves they can transition downwind without further thought.

Then they get very close to max Tq in the zero airspeed condition having lost ETL and tilted the disc and actually overTq as they hit the rotor vortices just before gaining ETL
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Old 28th Jun 2021, 11:38
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I've used the 'running take off' technique a few times in the AEW MKII Seakings of 849 to get off the deck of the (now old) carriers. We would wait for a clear deck, line up right at the back, perform a 'running' take off and flop off the left hand side of the deck just prior to the ramp, around '2' spot. The idea was to slightly over pitch the blades for the initial 'flop' as to clear the deck then use the height to accelerate into the ground cushion and translational lift.

The 'Bag' often required a fair bit of help off the deck in hot and humid conditions when the fuel load necessitated a long fighter controller sortie.

Fun times!
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Old 28th Jun 2021, 13:30
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The idea was to slightly over pitch the blades for the initial 'flop' as to clear the deck then use the height to accelerate into the ground cushion and translational lift
Ground cushion? You must have only practised this dockside..
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Old 28th Jun 2021, 13:34
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Ground Cushion over open water?

Sounds like ground breaking news to me!

Darn tooting does not work for OH-58A's over Lake water!
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Old 28th Jun 2021, 15:35
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Sorry to say that you still achieved 'ground effect' over water.
Thankfully as it was pretty useful when conducting HIFR and Advanced single engine flight continued technique training.

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Old 28th Jun 2021, 16:49
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If you were 'overpitching the blades' how did you not exceed Tq and PTIT limits?
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Old 28th Jun 2021, 17:54
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Hi crab,

You would pull to the torque limit, whilst observing the PTIT limits as well, overpitching was probably the wrong terminology. That was enough to clear you off the deck with forward speed but would not have been adequate for a 'normal' lift into the hover and transition as, when you moved off the deck, you would not have enough lift as you would lose the ground effect of the deck.

Was a fair while ago but worked well.
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Old 28th Jun 2021, 19:17
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That makes more sense to me - a 'flop and drop' to gain speed
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Old 28th Jun 2021, 19:25
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Similar to the S76A+ in the South China Sea. Beep the rotor up to 107%, pull hard up to 100%(+) on both and as it leapt into its tortured path into the air push forward steeply enough so that the boom wouldn't collect the deck as you hurtled over the side. You then plunged towards the sea hoovering up the 200 ft. or so available. 30 knots and the judder would follow and you pulled out of the dive at about 50 ft..

American passengers in the back would go "Yee Haw". The Chinese passengers didn't worry. They had fallen asleep as soon as they had fastened their seat belts.
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Old 28th Jun 2021, 23:15
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AKA as “The Dance of Death” in the 76A.
Originally Posted by Fareastdriver View Post
Similar to the S76A+ in the South China Sea. Beep the rotor up to 107%, pull hard up to 100%(+) on both and as it leapt into its tortured path into the air push forward steeply enough so that the boom wouldn't collect the deck as you hurtled over the side. You then plunged towards the sea hoovering up the 200 ft. or so available. 30 knots and the judder would follow and you pulled out of the dive at about 50 ft..

American passengers in the back would go "Yee Haw". The Chinese passengers didn't worry. They had fallen asleep as soon as they had fastened their seat belts.
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Old 29th Jun 2021, 06:01
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Fascinating stuff, this is a facet of helicopter operations that’s probably little known to most people and us fixed wing aviators
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Old 29th Jun 2021, 09:03
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Similar to the S76A+ in the South China Sea. Beep the rotor up to 107%, pull hard up to 100%(+) on both and as it leapt into its tortured path into the air push forward steeply enough so that the boom wouldn't collect the deck as you hurtled over the side. You then plunged towards the sea hoovering up the 200 ft. or so available. 30 knots and the judder would follow and you pulled out of the dive at about 50 ft..
That's the puppy!

Exactly what we used for rig work as well. Unfortunately the Seaking was 'computer' (not recognisable as such by the yoof of today) controlled at 104% NR as set by the speed select levers. The collective pitch anticipators would help in maintaining rotor speed but you did still have a very small amount of transient droop at 100% twin torque in hot temps. Over speeding the NR wasn't an option sadly. (I can't remember the exact figure allowed in auto but I seem to recall 110%) Although, thinking back on it, you could have selected more than 104% but it wasn't the 'done' thing I assume.

Distant memories of the windscreen filling with vision of sea wondering when the ground effect and translational lift would kick in!
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Old 29th Jun 2021, 11:13
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Originally Posted by Fareastdriver View Post
Similar to the S76A+ in the South China Sea. Beep the rotor up to 107%, pull hard up to 100%(+) on both and as it leapt into its tortured path into the air push forward steeply enough so that the boom wouldn't collect the deck as you hurtled over the side. You then plunged towards the sea hoovering up the 200 ft. or so available. 30 knots and the judder would follow and you pulled out of the dive at about 50 ft..

American passengers in the back would go "Yee Haw". The Chinese passengers didn't worry. They had fallen asleep as soon as they had fastened their seat belts.
Used it in 'anger' a few time sin Nigeria too, aided by a boot of right pedal as you lifted so you could pull some more Tq. Not helped by having engines that hit the N1 limits more or less the same time as the Tq limit, just to make the scan more interesting, and your left thumb on the N2 beeps busy...
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Old 29th Jun 2021, 12:19
  #97 (permalink)  

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212man, yes flying the C, with the “B” gearbox was easier as the same engines topped out before the gearbox limits were reached so the “full power” scan was easier.

It didn’t really fly any better, though…especially as the MAUW was increased.
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