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Why no lower than 57 kts in moderate+ turbulence?

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Why no lower than 57 kts in moderate+ turbulence?

Old 9th Dec 2012, 18:53
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Question Why no lower than 57 kts in moderate+ turbulence?

Hi all,

I understand in moderate+ turbulence we want to reduce airspeed to reduce structural loads, but why do you think in the R22 POH it states 57 kts as the absolute minimum?

R22 POH Limitations Section:
"Adjust forward airspeed to between 60 knots indicated airspeed (KIAS) and 0.7 Vne, but no lower than 57 KIAS, upon inadvertently encountering moderate, severe, or extreme turbulence."

I guess it is probably a performance issue - to be able to maintain best climb maybe, but that number is 53 kts...

Any ideas?

Without understanding more I think I would just aim for 60kts and try to keep the ship level.

Many thanks for your thoughts,

Jay
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Old 9th Dec 2012, 20:02
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57 Kts

Suggestion: Call up Robinson, get the test pilots office and ask them. They will know.
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Old 10th Dec 2012, 00:02
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Because that is the airspeed it is most stable at.
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Old 10th Dec 2012, 00:24
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Its because 57kts ias is at the bottom of the power curve, when you encounter severe turbulence its the t/r thrust that tries to roll the helicopter leading to mast bumping (very simplified statement I know). Thus the less power in use equals the less amount of roll which. thats why when you encounter low g, not only do you use the gentle aft cyclic you also lower the collective.
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Old 10th Dec 2012, 07:09
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Because Robinson require operators to do a lot of strange things to keep their products from falling out of the sky!
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Old 10th Dec 2012, 07:15
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Supple

Oh dear, I hope you have a Kevlar helmet and are about to retire to your trench in the back garden, as you will have a lot of " incoming" from the I love Robbie brigade, good luck
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Old 10th Dec 2012, 07:29
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Ha ha - let them rain down their abuse, I'm ready!

People don't love Robinsons by choice. They defend it because the helicopter school they went to had nothing else and so they themselves had no choice.

Then, as they gain awareness of the industry they suddenly realise "Oh my God, I've been duped, they're teaching me to fly in a souped-up lawn mower" and so they have no alternative but to defend the heli or to deny that they have ever flown one - most defend it.

So, flying schools all over the world - have pity on your students this Christmastime and buy a decent training helicopter.

I hear they are still producing the Bell 47.

Hughes - now that should attract some flack!
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Old 10th Dec 2012, 07:39
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Now I know of a secret nuclear bunker not to far from you
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Old 10th Dec 2012, 08:04
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Supplebum ......Now we are all showing our age banging on about 47,s . Do i think it is a great training ship ...Yes . Would i love to have one in the garage just for those summer evening going 50 miles down the road for lunch ...Yes . Most of these guys flying Robbos will never have had the chance to even sit in one and if they did would be all over the place with the throttle . I think the 300 is probably the best now .
Getting back to turbulence in a Robbo .....do you really have to cyclic back and REDUCE collective in low G .....i would have expected to raise collective ....so i would be another Robbo statistic straight away .....
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Old 10th Dec 2012, 10:26
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Maybe because...

as low is your airspeed, your maneuvers (control movements) increasing and keeping the aicraft stable is harder. So simple, I think. Try it in some flight device in IMC and you know the difference.

Last edited by hostile; 10th Dec 2012 at 10:27.
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Old 10th Dec 2012, 16:58
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Thumbs up Definitive answer

Thank you all for your input. Now, side-stepping the anti/pro Robbie hijack of the thread () I have been given what I think is the definitive answer to the original question (Why specifically 57 kts?):

The answer was provided by Raven on another forum:

The airspeed you fly in turbulance is a range. 60 is the low point 71.4 (0.7 of 102) is the high point. If 0.7 of any other Vne (remember it goes down with altitude and tempurature) is less than 60, you must go 60. However, at 10,000 feet and 30 degrees, you cannot go 60, because your Vne is 57! Hence the one exception, "no lower than 57".

Learning something new, one post at a time - thanks to Raven and all that tried to help answer this one.

Last edited by JB77UK; 10th Dec 2012 at 17:00. Reason: bad spelllling ;-)
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Old 10th Dec 2012, 17:07
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What sane person would go to 10,000 in a R22
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Old 10th Dec 2012, 19:22
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I've been there, and auto'd down for an engine off fantastic!!
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Old 10th Dec 2012, 22:21
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auto from that altitude 'all the way down' somewhere low, the ears must hurt from the sudden pressure change. Make sure you swallow saliva a lot..

Anthony, I'm (so far) pure Robbie pilot and I wish the job market and RELATIVE affordability were otherwise, for people paying from own pocket/inheritance/years of savings, and I'd have gladly jumped to 269/300 instead from the scratch. We work with what we can/have to.

Other than R44 charter/sightseeing, fewer and fewer countries have fresh CPL guys going straight to copilot seat. Then again, 22 time is useful for 44 jobs getting towards turbines.

It's easy to slag off stuff you don't need to use/train/work with and have little to no experience of. I don't bitch about your negativity, I just put things in context. What you 50-60yo+ 'oldies' know about breaking into civvy industry without having rich background, lucky to be in certain countries (at the right time) with 0-CPL cadet schemes for helicopters or going through basic training in the military or similar, NOWADAYS?

Last edited by MartinCh; 10th Dec 2012 at 22:36.
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Old 10th Dec 2012, 23:21
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I can't help drawing a parallel....

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Old 11th Dec 2012, 01:02
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I reply to you martinch.

Just because someone is 50/60 years old dosent mean we never had it easy when we were starting out. Just because we have the experience to know a cheap and nasty helicopter when we see one isn't a bad thing either no good getting older if you don't get wiser with it.

Now by the sounds of it you are one of these "young" blokes that want it handed to them on a plate because you have some idea that you are owed it just because.

We learnt in what was around at the time just as you probably have we were just a bit luckier having helicopters that were a bit more robust, just as underpowered as the r22 and maybe even more underpowered.

Anyway point being none of the old hands had it any easier than you in fact probably harder.
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Old 11th Dec 2012, 09:03
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@shytorque
Best Video ever, parallel R22/normal!
Thanxx!
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Old 11th Dec 2012, 09:57
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Subtle nigelh, subtle, they will still be working that one out re the collective.

And yes the G5 parked out back with a built in vertical to make it real would be very nice.

I agree, the CBI is probably the most versatile, hardest to hurt yet very handy machine around at the moment, still with a bit of a requirement to test the vacant space between the ear lobes regarding throttle control and some room to move to set up - "things".

JB77UK

Give us a break mate that's all gobbledegook.You seem bent on feinting with a question then supplying the answer which may or may not have substance. For mine, and i have been in just a tad of turbelence around thunderstorms and the like over the years at low level amongst largish hills, you can stick your 57 knots where the monkey put the peanut. Slow right down as nigelh says and get the collective well up at slow airspeed.. Positive - Power - Control.

Martins ch,

Bell 47 G2's had far less power to weight ratio than any marque of the Robinson family and were far far harder to get into translation and out of trouble if one ventured near it.
The trouble is nowadays the blessed Robinson is so easy to fly that qualified, ahem, I mean licensed pilots from them have so much to learn in the real world that they're pretty much useless for a long time.

cheers tet
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Old 11th Dec 2012, 13:00
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JB - the other reason that the answer you got is flawed is that if your VNE is 57 kts at 10,000 feet and plus 30 - you won't want to be flying at VNE in turbulence! Unless you like RBS that is.

Nigel is right re collective - don't lower it except to slow down.
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Old 12th Dec 2012, 18:26
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Grrr @TopEndTorque - Give us a break mate!

@TopEndTorque:

Not sure why the attitude - it was an honest and sincere question. And to be clear all I was asking was "WHY is the number 57 knots mentioned in the R22 POH as the minimum, as opposed to 60, 53, etc" I wasn't talking about what you or anyone else ACTUALLY does in turbulence, I was just hoping the vast cumulative hours of experience and knowledge that comes from the pilots that use this forum might help me find the answer...

I had posted the same question on another forum where Raven5 posted an answer that to me, made perfect sense and answered the question of why 57 kts and so I posted the response - simple as that - I hope that addresses your "You seem bent on feinting with a question then supplying the answer"

As for your accusation of "that's all gobbledegook" and "supplying the answer which may or may not have substance" - I truly thought it was correct, but did say "I have been given what I think is the definitive answer to the original question...". The answer was also confirmed by other posters on other forums.

But to make sure I called Robinson Helicopters in California and they confirmed that is EXACTLY the reason the 57 KIAS is in there. Enough substance for you?

I got to say I come to this forum for respectful advice, so I respectfully quote you TopEndTorque when I say "Give us a break mate!" [insert Australian accent]
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