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Rotor blade stall

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Rotor blade stall

Old 23rd Oct 2018, 17:48
  #21 (permalink)  
 
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Sasless - when I said I knew someone who had done it, I didn't mean me

Anyway, according to Lord Flashart (from Blackadder) you should treat your aircraft like your woman - get inside her several times a day and take her to heaven and back
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Old 12th Sep 2020, 10:22
  #22 (permalink)  
 
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Originally Posted by SASless View Post
Crab, One should treat the helicopter like a girlfriend and not a wife.....gently, softly, lovingly but firmly!
OLD comment, but I had to say it......I would much rather treat it like my wife. She never goes down on me XD
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Old 12th Sep 2020, 11:58
  #23 (permalink)  
 
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Imagine watching that film when you were training on wooden bladed Sycamore helicopters.
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Old 13th Sep 2020, 13:23
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There is a well known story about 22 squadron SAR in the sixties, when they still had the Whirlwind 10. One of the pilots posted in was a failed fast jet pilot, and he was disgruntled about being landed with Helicopter flying. He took out his frustration on the poor old whirly, by putting the old girl into a power dive, exceeding VNE. Several other crew members knew he did this, but nobody reported him.
The inevitable happened, and he hit retreating blade stall, crashed, and if I remember correctly. killed his Navigator, and put himself in a wheel chair.
There was much made of the fact that not one of the other crew members had reported his actions.
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Old 13th Sep 2020, 15:14
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Is the most recent example we have of RBS from a helicopter with a radial engine that retired from service 30 years ago?
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Old 13th Sep 2020, 16:22
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Dave B - Partially correct. The pilot was, indeed, known for stupid risk-taking- hovering with wheels on the Ops room (Seco hut) roof, Marine craft 'beat-ups' and the one which killed him, his winchman and a passenger, and injured his Nav/WinchOp, was low level 'terrain-following' over the Downs. His ultimate stupidity was to 'revert' to fixed wing practice and pitch down for the valley slope rather than the helo-required lower collective. RBS did the rest.
Why do I know this? - I was at Valley at the time and the 22 Boss had promised me the very next posting to S England ... he was as good as his word and I was posted to Thorney to replace the dead winchman at such speed, that my first job on shift was to pick up my predecessor's effects from the crash site. The Boss, shortly after, came to 'debrief' us. His primary point was that the flying behaviour of the culprit was known, and had been, for a long time. The risks being posed were obvious to anyone with even the most basic understanding of 'airmanship' ... and nobody had done anything about it!
In essence, it was a complete parallel to the 'back story' of Lt Col Bud Holland, with similar results. Unfortunately, it is not unique, nor, I suspect, will it ever be. There will always be the self-regarding 'ace-of-the-base' in aviation, and much else, who cannot, or will not, see beyond their own self-image. If they are lucky they will only destroy themselves - too often they take others with them.
Why so harsh? - During my S&R time, I saw more than enough results of unavoidable 'incidents'. To fail to take action on obvious potential for such, is, in my opinion, unforgiveable.
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Old 13th Sep 2020, 17:21
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Originally Posted by Cornish Jack View Post
...
In essence, it was a complete parallel to the 'back story' of Lt Col Bud Holland, with similar results. Unfortunately, it is not unique, nor, I suspect, will it ever be. There will always be the self-regarding 'ace-of-the-base' in aviation, and much else, who cannot, or will not, see beyond their own self-image. If they are lucky they will only destroy themselves - too often they take others with them.
...
We all can use a reminder every now and then, Ltc Holland's story: Darker Shades of Blue.

Does history repeat itself? No it just burps, and we taste again that raw-onion sandwich it swallowed centuries ago (paraphrased quote of Julian Barnes).
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Old 13th Sep 2020, 18:50
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Jim, the WW10 had a `R-R Gnome turbine engine...The RN still operated Mk7 WW,with a Leonides Major radial....
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Old 13th Sep 2020, 19:02
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Originally Posted by sycamore View Post
Jim, the WW10 had a `R-R Gnome turbine engine...The RN still operated Mk7 WW,with a Leonides Major radial....
Thank you, I stand corrected.

Then, is the most recent example we have of RBS from a helicopter whose origin dates prior to 1953?

Last edited by JimEli; 13th Sep 2020 at 22:11.
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Old 14th Sep 2020, 09:23
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The Navy had radial engined one at their admin base at Labuan, Malaysia in 1966. It didn't fly much; it had trouble getting over the security fence around the dispersal.
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Old 14th Sep 2020, 10:15
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Originally Posted by sycamore View Post
Jim, the WW10 had a `R-R Gnome turbine engine...The RN still operated Mk7 WW,with a Leonides Major radial....
But the RN also had the Whirlwind 9. SAR, and Endurance Flt I believe.

Last edited by 76fan; 14th Sep 2020 at 10:34.
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Old 14th Sep 2020, 11:24
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76,Correct,in Sept.`69 I flew XM666 on it`s SS11 missile Clearance and Firing Trials at B-Down and West Freugh,before Endurance went South to the Falklands,as someone had `foreseen` there were `Argentinian rumblings of discontent` in the area...It later either ditched or f/landed and could be seen in someones backyard on W Falkland when I was there in 92 on C-130s...might still be visible on GE....
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Old 14th Sep 2020, 11:46
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Jim, I think modern rotor design has done much to minimise RBS.

After Wessex (which could definitely get RBS) and Gazelle (which sort of protected itself with jackstall but behaved the same way) I went to Lynx with CMRB (the BERP tips) and I became convinced that you could not get RBS with those. The aerobatic flight routines should have been on the edge of RBS given the loading on the disc to produce 3G and do hover to hover back flips but I don't think anyone even came close.

Now helicopters have such high VNE compared to Whirlwind the boundary is probaly much further away in normal useage.
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Old 14th Sep 2020, 14:44
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Originally Posted by [email protected] View Post
Jim, I think modern rotor design has done much to minimise RBS.

After Wessex (which could definitely get RBS) and Gazelle (which sort of protected itself with jackstall but behaved the same way) I went to Lynx with CMRB (the BERP tips) and I became convinced that you could not get RBS with those. The aerobatic flight routines should have been on the edge of RBS given the loading on the disc to produce 3G and do hover to hover back flips but I don't think anyone even came close.

Now helicopters have such high VNE compared to Whirlwind the boundary is probaly much further away in normal useage.
Someone gets my gist. Thanks Crab.
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Old 21st Sep 2020, 18:13
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The Lynx with the original metal straight blades would suffer from RBS IIRC. When we moved over to the composite BERP blades the AOB was restricted from 90 down to 60 as the blades were far more flexible and thus it was feared a blade/body strike could occur. It never did in all the years I flew it! Vibration in the hover was a side effect of the BERP blade though and you could get a very uncomfortable 'cobblestone' vertical bounce with certain wind speeds! The Dutch Navy complained about it for years!

I do remember 'jack stalling' during display routines occasionally. Nothing to do with the poor aircraft just ham phistedness on my part!!!
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Old 22nd Sep 2020, 07:01
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Jackstall in a Lynx??????? Don't think so. It had a marked pitch/roll couple that rolled you right if you just pulled back on the cyclic but that was it.
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Old 22nd Sep 2020, 09:23
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Sorry to say but definitely 'jack stall'. The manoeuvre was run low level toward the crowd line, 150kts to 90 degree nose up, wait for zero climb, 180 pitch down to vertical with a rapid 360 roll once in the vertical.

I was flicked out of that manoeuvre with an associated master caution! As stated, not any fault of the aircraft, it was extremely gusty and my handling was probably a bit off.
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Old 22nd Sep 2020, 11:46
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There is a jackstall caption on the Lynx? - must have missed that in the 7 years I was flying it??????

Was it an AAC Lynx?

At what stage of the manoeuvre were you 'flicked out'?

Did you forget to take the AP out?

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Old 22nd Sep 2020, 12:12
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Hi Crab, nope, was a Lynx HMA Mk 8 with a bolted head! The warning was for Hydraulics which, after consultation with ETPS, we came to the conclusion that one of the primary jacks had briefly bottomed out/jack stalled. It came as a surprise to me and an even greater surprise to my Observer hence we had a good look into the event as the Mk 8 hadn't been around for long at the time. We were flicked out at 90 degrees nose down executing a rapid right hand 360 degree roll IIRC.

It was a fair few years ago but I do seem to remember that I flew displays with stab out!
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Old 22nd Sep 2020, 12:18
  #40 (permalink)  

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Never managed to jack stall the Puma but it certainly let you know if you pulled back on the cyclic too hard. The sudden onset of airframe vibration was very noticeable and the collective pitch gauge needle oscillated rapidly. The recovery was instant if the severity of the manoeuvre was reduced, either by cyclic or collective.

Recovery from 90 degrees nose up was best done using yaw, rather than nose down pitch. If you pushed over too sharply in that airframe it was possible to cavitate both hydraulic pumps because the oil reservoirs were unpressurised. Only did that once!

(Just like to add that I only found these things during properly authorised display flying and not during normal operations. The display was later discontinued after two subsequent pilots found out the hard way that you can only stress the Puma airframe so far before it can suddenly go pear shaped - thankfully in both cases without the very worst happening and the damage not actually occurring to the main rotor).

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