Quote : One more time Robinson is only slightly improving a design coming from the R-22 which came from the Hugues 300, which was developed in the 50'.... what an improvement!

Have you ever lifted the cowl on a Robbie?
The R22 is nothing like the H300!! The 300 is overcomplicated, the R22 is the most successful due to its simplicity...........

Someone please correct me if I am wrong about this: THe R22 and R44 are uncertifiable as instrument ships in the US. Yes you can train in them, no you can't go IFR in them.

There is simply no excuse for going into a cloud as a student, if its so bad out they can't avoid them, they shouldn't be flying.

While I wouldn't take an R22 or R44 into actual IMC I have no qualsm about flying them daily for work, excellent machines, well built, well engineered and if I was to buy a personal helicopter the R44 would be my number one choice...

Negative G Recovery... lower collective?
 

Does anyone know the latest on Negative G recovery?
As well as the "aft cyclic to load the disc" method, I learnt to drop the collective in New Zealand: It certainly seemed to work.. removing the yaw that lifts the fuselage.. but I haven't come across anyone who seems to have heard of this in UK.... I would like confirmation of my recollection of the theory involved - it was quite a mental overload going through it at the time!!:eek:
Anyone care to comment if it is taught where you are? What's the official line from across the pond and Frank Robinson?

Thanks for the diag... but
 

I can't see how windage alone can lift 1000+lbs at 30 knots sidewind.... well not more than a few degrees whence the windage will be reduced. Plus the fuselage seems to lift more as the speed comes off, not the opposite.
Humour me for a moment: What about these suggestions for the melting pot as other causes of the fuselage lifting:
1:Perhaps: The precessed centrifugal force of the tail rotor on the tailboom due to (perhaps) changing asymetry of lift across the tail rotor as the forward speed reduces (transient change) - this force might seem to twist the tailboom/ fuselage only laterally (once precessed) but.. as the nose of the fuselage is coming up it may have a component with twisting affect on the fuselage upward?
2: Or: As load comes off the main rotor, drag is reduced altering balance of torque. Now..focussing on the rotating driving units below the hub like the mast and in the gear box... as the nose of the fuselage lifts upward a 90 degree force might be precessed on these rotating parts, thus lifting the leftside of the fuselage upward. (anticlockwise main rotor)
I feel theory 2 has some potential....
Any thoughts from the wiser grey matter? ? NickL?

K48. The problem is not much to do with lifting force. It is simply as the diagrams show.A two bladed helicopter with a gymbal head hangs underneath the rotor and the only forces that keep the fuselage in the correct relationship to the rotor is gravity (plus centrifugal force in a turn). Remove the gravity by pushing over and the fuselage is free to adopt attitudes under the influence of other forces, in this case tailrotor thrust which is above the vertical C of G causing the right roll. Stick to the recommended recovery, it works. We used to routinely demonstrate it to students and have them practice it, before some people got a bit carried away and took the demo too far.
Incidentally all two bladers do it, just a bit more slowly than the R22.

Rotorfossil
 

Thanks, I agree, stick to what you were taught. Or better don't go there at all! (make note to the longtime fixed winger above...:eek:)
But for discussion:8, I was taught both methods in NZ and wish to discuss it further globally as outlined above.:) The lowering collective method was simpler, very effective indeed and purportedly less error prone as no cyclic input is required thus eliminating a premature left cyclic input.

Cheers!

Low G etc
 

So, lets take this discussioan a bit further. What kind of issues arise in a helicopter with a full articulated rotor in low G conditions? All the discussions seem to focus on teetering semi rigid rotors. The rough equivalent of mast bumping for a teetering rotor would seem to be droop stop pounding for the articulated rotor. Is there more, is low G with a fully articulated rotor dangerous, and are recovery methods similar? Cant seem to find much discussion of this topic in the usual training materials.

Thanks,

RB

Hi K48,

I drop the collective to correct this (have to allow a student to go as far as possible first) speed increases rapidly so there is a need to reduce it slowly to keep RRPM from going too high when you flare.

Don't remember being taught this it just seems to be the best thing to do in the situation given all the info. Eg. rotor close to tail etc. .

Rick, No restriction on neg G with Enstrom articulated head except 'no aerobatics' - Its a matter of degree. The limits are way beyond what a Robbie will tolerate, to the point That I think you would have to push really hard to get there. I have experienced neg G to the point where things float off the seat-with a very experienced instructor on board. It wasnt planned.:eek:
I tend to avoid it - I trained in a 22.
As you know the head is fixed to the mast with the blades being attached about 6 inches from the centre of rotation. This gives the blades positive control over the mast unlike a teerering head. This arrangement is fine for much more spirited flying than you could get away with in a Robbie but it does not have the same authority as a fixed head. Yes, theoretically, if you push it too far it will contact the bump stops but I think you would have to be seriously mad to do it. The Bolkow is more aerobatic.The blades are fixed to the mast rigidly so more authority. The ultimate extension is the model where the blades have enough authority over the mast and the whole lot is strong enough for it to hover upside down. To do this in full size would be a massive (impossible?) problem due to the huge forces involved.
The teetering head has minimal control over the mast.
Do you need diagrams of force couples on the head or does that explain it?

Low G
 

Gaseous,

Thanks for the reply. Are you able to direct me to web or other resources that treat this in greater detail?

Thanks,

RB

Yes Rick, Norman Baileys book, The helicopterpilots manual Vol 1, has a brief section on rotor head authority or as he correctly put it, Control power, page 61 on. I just edited my post above to avoid some flak from the more pedantic who stalk here.

Edited to add the word 'correctly' to keep 212man happy.

That's what it's called: it's not his 'name for it'.

Someone above said that one school tweeked the rrpm to the high end of the permissable band, I assume they did this when setting the auto rpm, (which is more than likely the problem with old mate's machine, the auto rpm that is). A lot of pilots I talk to would agree to this train of thought.
I have a lot of experience mustering in the 22 and it's worth thinking that if you were to have a power loss auto at low level, a high initial auto rpm is not nesseccarily a good thing. Up high probably not so critical as height is your friend, I think.
Consider the auto descent rate is 1500 ft per minute in a correctly rigged machine. Or that is what it states in the POH. If the rigging were set for a higher initial rpm, then when the collective is jammed to the floor in a low level auto, the machine will descend at a rate higher than 1500 feet pm, for instance lets say 1700 feet pm. Do we now have the time to reestablish 1500 feet pm before we collide with the ground. The machine is designed to arrest the rate in a properly executed auto of 1500 fpm but maybe not 1700 fpm.
Just food for thought before you start stuffing around with higher auto rpm's

I'm new to this gizmo and seem to have posted this to the wrong thread.
my apology's

Just food for thought before you start stuffing around with higher auto rpm's
 

Mate, I hope you never have an engine failure.

Why? please elaborate.

Wow, I never realised how dangerous Robinsons were until I read this thread - I think I'll stick to my geriatric Hughs tool works product :E

If its permissible by the book, thats OK.
I think entry RPM and ROD is more affected by the size of the flare than the rigging.
The rigging procedure is designed to maintain adequate RRPM in steady autorotation at minimum weight.
I used to fly a helicopter that was rigged with the auto rpm set too high. The problem was that at high power settings it used to bang on the stop at the high end! I got it sorted pretty quick. Running out of collective is not good.
There is only one way to rig. As it says in the book.

The issue with R22's in auto is that the rate of descent in auto is about 400 fpm greater if the rpm are towards the top of the band than if they are about in the green sector, increasing the ground rush impression. Also you then have an overspeed problem in the flare unless indulging in some fancy collective work. The best compromise we found was to have the auto rpm two up at normal training weight adjusted to 106%, lever fully down. However this meant readjusting them down a bit as the summer temperatures came in and then up again in the autumn.