From: mpaton@oakhill.sps.mot.com (Michael J Paton)
Subject: Re: Helicopter icing and IFR
Date: Wed, 11 Nov 1992 21:01:02 GMT
Reply-To: mpaton@tempest.UUCP (Michael J Paton)
Organization: Motorola Inc., Austin, Texas
Keywords: helicopter,ifr,icing

In article <1992Nov11.025904.8159@cirrus.com> gopal@cirrus.com (Gopal Ramachandran) writes:
>In article <pdb1.721416200@Isis.MsState.Edu> pdb1@ra.msstate.edu (Philip D Bridges) writes:
>>
>.....
>>3. IFR helicopters are generally flown by professional pilots and   
>>   usually have 2 pilots in the cockpit....
>....
>
>A very informative response by Philip. I've had only a few lessons in
>helicopters, though I have a fair amount of fixed-wing time. I noticed
>that in the simple, training helicopters I was flying, it was not
>possible for me to free up my hands (or feet) for any length of time.
>My instructor told me this was why helos needed two pilots in IFR
>operations. One pilot was on the controls full time, and the other
>copied clearances, tuned radios, etc
>	However, I believe that turbine helos have stability
>augmentation to some degree. Presumably, one could let go of the
>cyclic without the helo getting away from you while you were retuning
>a radio. I wonder if they can let go of the collective/throttle
>twist-grip as well due to a friction device as well, in order to free
>up the other hand as well? Or are there other good reasons
>(certification?) to not allow single-pilot IFR in such machines?
>
The odds are that Gopal flew a Robinson R22, as there are more of them used in 
training than anything else. I certainly haven't found it possible to let go
of the cyclic in the R22, but it's certainly possible to let go of the
collective for brief periods of time. Of course you still have to watch RPM,
and you still have to be able to dump the collective to the floor in the
event of an engine failure.

A friend is training in a Hughes 300C and he tells me that as it has 2-axis
cyclic trim, it's possible to fly it hands off entirely for brief periods.

It is normally a requirement for IFR certified helicopters to have some
form of SAS or Stability Augmentation System. This does not need to be an
autopilot, merely a device to allow hands off flight. Frequently the
requirement is met by an autopilot. I would guess that more than half the
helicopters flying are not certified for IFR flight. 

Quite a number of R22s are IFR equipped but not certified, so that they may
be used as IFR trainers. I did my helicopter instrument additional in one
of these, and I am happy to tell you that I found the instrument checkride
MUCH more relaxing than the private the previous day. 

Helicopter instrument is quite interesting. There's that pitch up or down as
you enter a turn that's much more noticeable under the hood. And the ball
doesn't sit in the middle (translating tendency correction you know). 
Remeber the arguments about whether to adjust pitch or power when below
(or above) glideslope? Well in a helicopter the longitudinal cyclic and
collective controls are much much less coupled than their equivalent fixed
wing controls. So the cyclic can be used for airspeed control, while the
collective is used for glidepath control pretty much independently. Makes
an ILS very much easier. There are disadvantages too, like the speed or lack
of it. The R22 flew approaches at 85KTS most of the time, and my checkride
had winds of 25KTS. 5 minutes outbound is an eternity. You also even get to
check the operation of all the attitude instruments in a hover prior to
departure.

My examiner played autopilot, and was very good at it too, although I was 
pretty careful to cross check what he did. He would start and stop timers
on request and tune radios. He gave only simplified clearances, so I don't
think there was much to be copied. Best of all, he flew the helicopter for
as long as I wanted in between the approaches on instructions I gave him
while I got my plates and radios set up for the next approach. This was a bit
more than I'd been expecting, but certainly demonstrated the value of a good
copilot in helicopter IFR.

Michael Paton
mpaton@tempest.sps.mot.com