Day 6 of Ground school – Primary Flight – part 18

We focused on a few things today.  Straight and level flight, coordinated turns, normal approaches, and finally we discussed the height-velocity diagram.

Straight and level flight requires a few things.  If there is wind it requires a few more… the pitch of the heli, more or less, gives you forward track.  How much power you’re pulling determines if you’re climbing or descending. In the Guimbal there isn’t much of a “sight picture” or much on the front of the windscreen that allows you place something internal to the helicopter on the horizon to keep the thing level. In the R22 or R44 most folks use the magnetic compass… I keep an eye on VSI and the attitude indicator. When it’s windy I keep an eye on the trim bubble then step on the ball to keep the track. For the most part if you’re pulling 80% power you can fly level at around 80 knots. That changes with temp, wind, weight, etc… but for 2 200lb dudes with 15 gallons of fuel, that’s what we’re seeing in the G2. Mileage may vary.

Coordinated turns take some practice. There are a few things that I did right when learning how to fly and there are a million that I did wrong. Coordinated turns were one thing that came easily from hour 3 or 4 of actual flight. What I do is try to keep everything in trim and get ready for adding a little power. If you bank without power you’ll drop some altitude, if you pull aft on the cyclic you’ll drop airspeed. I get ready with the pedals(if I need to stay in trim), pull a tiny bit of power, if I’m at 80% maybe 82%, and roll the cyclic. Pedals keep the trim string / ball where it needs to be and just like that you’re instructor isn’t frustrated and silently judging you and you’ve executed a decent turn. Wind and other outside forces come into play but this one is easy. There is something known as slipping or skidding you’re turns but I haven’t had an issue with it so I’m going to stick with just being good at something for once and ignore those for now.

It’s probably a good thing to talk about spacial disorientation at this point. In short you, the pilot or crew, cannot tell where you’re body is at in space. Basically you’ve been leaning to one side so long or in clouds for so long or generally doing something weird and your body gets used to it. I lived in Montana for a long time and as any good college student did, we snowboarded every other day. Lots of hiking to backcountry spots and lots of riding in whiteout conditions… anyway, descending quickly in clouds or heavy snow storms created the “white room” where you couldn’t figure out which way was up even though you might be dropping a chute or cliff band at 40mph. Sketchy. Check your instruments, trust your instruments.

Approaches… I’m not sure how many approaches I’ve made in my VERY short tenure. Maybe 100. I fully expect that by the time I solo it’ll be 1000 so while I’ve done it in practice I’ll probably explain this very poorly because I just can’t nail this part yet.

In the rotorwing handbook an approach is described as: “A normal approach uses a descent profile of 8°–12° starting at approximately 300 feet AGL.”

What we hear over and over in class and in flight is “a nice walking pace”. What that means is when approaching your spot you walk the helicopter to it at an even pace and even sink rate. To much in any direction and you’re putting yourself in a dangerous position should something like an engine failure occur. Also, from that altitude it looks like you’re approaching at a “walking pace” even though you’re at 40 or 50 knots depending where you are in your approach. I hate to leave it as one of those that you need to do to understand but there is only so much the handbook can teach you before you go out and do it a few hundred times.

Guimbal_G2_HVFinally we talked about the height-velocity diagram.  Every helicopter has it’s own HV diagram.  This one is out of the G2 handbook, it states “With a view to simplicity, the same domain was demonstrated regardless of altitude and temperature.  It means that some margin exists at lower altitudes, temperatures and weights.

During take-off the pilot should pay attention to avoid this zone.  In addition, he should limit the rate of clime to a maximum of 500 feet / min below 100 feet AGL, in order to limit the loss of rotor speed in case of power failure.”

The column to the left is the altitude AGL.  The bottom is the knots or Indicated Air Speed.
What does all that mean?  Basically stay out of the shaded area, don’t pull a bunch of power and grab altitude with no forward airspeed.  If bad things happen your day will go poorly.  Low inertia rotors have a pretty abrupt rotor decay.

I also noticed something in the handbook which I hear a bunch in my when flying with Grant… I always grab a bunch of power when taking off, he’s convinced I can take off with no increase in collective.  For some reason my tiny brain won’t let me get a running takeoff without pulling more power.  I can’t seem to break myself of this habit but there it is in print…


height-velocity diagram

Anyway, that was about it for that class.