Advice requested re helicopters in highly thermic conditions

[outofwhack]

How much is too much? This is really aimed at helicopter pilots who also fly fixed wing.

I am a very new commercial helicopter pilot just starting privately building hours in a B47 in Australia (100 hours TT so far and all under instructor supervision where instructor has said turn up today/dont turn up today).

But I have more than 1000 hours flying sailplanes (gliders) in highly thermic conditions [and light fixed-wing singles in similar thermic conditions - typically to get to the gliding club].

Also have at least 100 hours in strong wave conditions in sailplanes in New Zealand mountains [ often the local helicopter joyflight operators are staying on the ground at these times but not sure real reason why - pax comfort? or helicopter limits?]

So I feel very much at home flying fixed-wing in strong thermic or wave conditions and know where not to fly - avoiding sink, curl-over and rotor.
Lets define highly thermic conditions = occasionally needing full aileron one way to keep the wings level in a fixed-wing single or glider
Main Questions:
Can a helicopter cope with the same weather conditions as fixed wing?
Do I need a new set of personal rules with regard to go/nogo in helicopters?
Do you guys avoid these conditions by steering around obvious thermal indications like cumulus?
Do you find it better to fly low when thermals are present or prefer to get above cloud base where thermals have ceased?
So many questions!
OOW

[Arm out the window]

Two words popped into my mind as I read your post - Shirley Strahan!
Having said that, you're probably pretty well clued in to the ways of strong mountain waves from your gliding so as long as you apply that knowledge to your helicopter flying you'll be OK.
I guess you're trying to get a feel for what's acceptable as far as how bouncy the conditions can be around the hills when you take your helicopter in - teetering heads are obviously vulnerable to low g conditions, so pressing on into big bumps isn't a great idea. But how big is big? is the question, I suppose. The main things to my mind are to not press too much, don't wave the controls around too much, set speed with cyclic and use collective to fly up and down hills, and don't bunt.
I've been into some quite uncomfortable conditions around the hills at times without getting into trouble, but of course it's a grey area. I'd be a bit more cautious in a Robinson than a Bell, but I don't know the Robbos that well so I may be bad mouthing them without grounds.
I guess with the area winds up at 25 - 30 kts or more it's going to be getting at least uncomfortable if not dodgy up in the hills as a ball park figure.
John Eacott may be a good source of words of wisdom, as I believe he does a lot of flying around the Snowy Mountains and probably mixes it with some less than salubrious conditions sometimes.

[Hoveronly]

Operating a fixed or rotary wing in choppy conditions is not a great place to take ones passengers. Though I find a helicopter less susceptible to downdraughts etc.
Interesting that the local helicopters should have been on the ground. Ring or go visit them and ask why, their local knowledge is certainly better than via email. ;)

[996]

I regularly fly in rough conditions and have done for many years so FWIW here are my thoughts:

1. Root reversal.
2. Retreating blade stall.
3. Increase in wear 'n' tear.

Apart from which it is just damn knackering physically. Your muscles are constantly working to help maintain posture and orientation whilst in flight. [Same as in a car on the highway] so the more rough it is, then the more your muscles work. This is an automatic reflex response and you will be mostly unaware of it until the physical weariness becomes apparent.

Anyway, most helicopters have a w/v limit for stopping and starting rotors [blade sail] and that is usually the deciding factor. As for the actual flight conditions, well that's the trick - to make passage along the least turbulent course and it takes a lot of skill and experience to achieve. during which you could very well go through a few pairs of shreddies.

[gulliBell]

>Can a helicopter cope with the same weather conditions as fixed wing?

Unless this is an abstract academic question about design structural limitations between the 2, a practical answer is that more often than not, continued flight is more a question of piloting limitations rather than the physical limitations (turbulence) which the aircraft can withstand. Generally helicopters can cope with worse weather than fixed wing because the helicopter pilot can slow right down, and fly lower if required, to maintain visual reference to the ground or water.

>Do I need a new set of personal rules with regard to go/nogo in helicopters?

The rules are as prescribed by law, you need to know and follow them. As the pilot you have the prerogative to impose more stringent rules on yourself.

>Do you guys avoid these conditions by steering around obvious thermal indications like cumulus?

If the weather is visual, I fly A to B direct 99% of the time.


>Do you find it better to fly low when thermals are present or prefer to get above cloud base where thermals have ceased?

Number 1 rule, maintain visual reference with the ground or water, never fly above the cloud base in VFR unless you can go IFR to get down.

[helopat]

All excellent points above.

I guess my advice is stay within YOUR comfort zone. Early days flying rotary, your comfort zone SHOULD be fairly small so give it a miss on the nasty days. As you gain experience, you'll feel more comfortable with your ability to cope...then its a matter of whether your passengers are really up to the task.

As with fixed wing, avoid the lee side of hills (or stay above the area of turbulent air down low in the lee of the hills). Always leave yourself an 'out' in those questionable weather situations, and mind the wind if its coming up your backside (ie. potential for loss of tail rotor effectiveness). And, yes, if you see evidence of 'bad stuff' coming your way (virga, rotor clouds, evidence of downdraughts) give them a wide berth.

I like the fact that you're asking questions...thats ALWAYS a good sign in my book.:D

Keep the twirly side up.

HP:ok:

[outofwhack]

Hi All,
Thanks for the informative responses so far. My motive in asking is definately to avoid becoming a statistic like poor Shirley.

Reason I asked is I flew 2 hours today through quite strong thermic conditions in Queensland, Oz and it got me thinking back to a flight in a glider years and years back (so its not very often) when I was unexpectantly and quite rapidly tipped nose down from level flight what felt like 60 degrees while experiencing reduced G (probably even negative).

I wonder if that is surviable in a helicopter? [and I certainly dont want to try]

Would the gyroscopic stability in a helicopter prevent such a rapid onset of pitch? If it happened I know not to pull back hard like a fixed wing guy might but surely overspeed aint far off in the ensuing dive (specially in a B47). I guess overspeed is better than pulling back too much and loosing the tail etc? So I expect the correct answer is lots of collective, centralize and the minimum back stick to come out of the dive before going passed Vne. Pls correct if I have this wrong!

GB: I dont think all weather that satisfies the VFR rules or aircraft crosswind limits is necessarily safe.

I suppose I am really checking I havent missed any 'unwritten rotary laws' equivalent to those used in other flying disciplines.

e.g. Balloonists avoiding thermal activity altogether by flying early or late because a thermal can collapse their envelope and kill them, paragliders stay on the ground when thermals a stronger than 5knots because they dont have the range of speed to avoid being sucked into cloud. These rule are not written down.


As long as my fixed-wing experience 'weather experience' does apply to helicopters I am real happy :)
I heard so many times from helicopters schools that fixed-wing experience 'did not count' that perhaps I started to believe it !!!

Thanks guys

OOW

[topendtorque]

I heard so many times from helicopters schools that fixed-wing experience 'did not count' that perhaps I started to believe it!!!

Yes, you should.

From your posts, I conclude that your pseudonym is well chosen, you’re so far outside the square with way too much imagination to ever be an IFR driver.

Please don’t strain yourself too much, stick to the basics, always hang onto the sticks, or at least have the collective firmly locked with your knee when changing freq’s or whatever. The only times that helicopters go ballistic in severe turbulence is when d***heads at the wheel are not in control, everything else is rubbish.

I quite enjoy severe turbulence in helicopters and I’ve been in a massive storm front in deep ravines where beside me trees were snapping off due to wind gusts.

When I encounter far less than the same sort of thing in any sort of plank, I’m scared witless and will be quickly on the reciprocal goin’ ninety.

I don’t believe that turbulence is a real problem, in teetering heads or any sort of head perhaps, and others can comment on that.

I always maintain the integrity between the disc and machine, we are as one, you might say.

I do not disengage the rotor disc from the machine by trying to make it fly down when the machine is still going up, a-la-pushovers.

You would know that as the recipe for an out of control disc and broken tail booms.

But I say again, take your hand off the collective and fly into turbulence and you may easily encounter a sudden flick of the collective, up or down and if you live, you are lucky.

On a purely technical note, there is often a less disturbed boundary layer of air close to the surface on any leeside, have you ever seen a ship in a protected harbour?

[SASless]

Funny thing.....my limits on "Thermic flight" is less than the helicopters...and the gap widens with seniority (as in approaching old age).

I would suppose one would not have a seniority problem if it were the other way round.

[[email protected]]

......Also have at least 100 hours in strong wave conditions in sailplanes in New Zealand mountains [ often the local helicopter joyflight operators are staying on the ground at these times but not sure real reason why - pax comfort? or helicopter limits?]

You answered your own question - joy or pleasure flights are supposed to be just that, no-one will pay money just to get airsick in turbulence.