matten

I friend of mine ask me to set up an maiden his PCM Models TriStar L-1011, if there are some owners flyers of this model out there I will appreciate the answers and comments to the following questions:

1.- Is the CG at 1/2 inches aft the wing joiner tube the correct position for flying?
2.- How much shall weight empty and with fuel?
3.- How log is the take of roll with a 21-22 lb turbine? ( Modellbau T-750 installed)
4.- How much throttle for comfortable flying?
5.- Pich effect with full flaps?
6.- General behavior; stall speed, landing speed, etc?
7.- Minimum recommended hard top landing strip?

Any videos out there?

Thank you very much in advance for your inputs.

Best Regards,
Richard

rhklenke

My Feedback: (24)

Richard,

I can't answer #1 (don't have the plans here), but I can give you some info. on the others.

First, our application (NASA training) is concentrating on flying planes with high wingloading, so the one we have is ballasted somewhere around 37 lbs. wet. It flys fine at this weight. We're flying it with an AMT180 SP, and the takeoff roll is about 300 feet. It was about 75-100 feet shorter at the stock weight of about 27 lbs wet.

One up in the air, the plane is quite quick and even at this weight, we fly around at about 1/2 throttle for a cruise speed of 90-100 MPH.

There is no noticable pitch change with half or full flaps. We do not have any elevator mix in with flaps.

The stall speed is quite slow, but the break is definate. It will drop a wing in a stall - pretty much like the average jet.

Evena t the stock weight, the landing flare takes, shall we say, concentration. The best technique is to pull the throttle back on the crosswind leg to let the plane slow down and then put back in 1/4 throttle on the final approach. Then fly the airplane down to the runway and use the power to flare, then chop it and hold the airplane off until it settles. Once on the runway, DO NOT pull the elevator back. Doing that or letting the model touch down with too high a rate of sink will cause the model to bounce back into the air - sometimes quite high, and then you're stuck with no energy for a second flare. The result is busted landing gear. Ours has been fixed a number of time to prove it, but once we started landing it as I described regularly, it been fine since.

At the stock weight, I don't think I'd fly it in less than a 600' strip until I was comfortable with it.

Bob

matten

Thanks for your info Bob,

After you described the landing technique that you use, i have other questions;

Do you set the full flaps on the down wind leg or in the final approach?

Are you coming in of final with nose high and 1/4 throttle and go to idle when you reach the runway?

Touch down is with nose high ar almost flat landing?

Thanks again.

Richard

BalsaBob

My Feedback: (24)

In my Instruction/Operation Manual, it says the CG is at the 'rear side of aluminum main spar'. Looking at the plans, the CG (center) appears to be at a point about halfway between the center of the aluminum main spar, and its rear edge. Unfortunately, I cannot tell you how this CG location works .... my kit is still under construction. Bob

rhklenke

My Feedback: (24)

Richard,

We set the flap to full on the down-wind leg. We keep the model at 1/4 throttle and actually keep the nose down. We have on-board telemetry (although we fly a lot without it too), and our approach sppe is usually about 60 MPH. We find that if you keep the nose down a bit (not too much) extra speed on, it helps the flare. If you don't, you' won't have enough energy to arrest the sink rate, and you'll get more of an "arrival" than a flare. Touchdown is really mostly flat. DO NOT attempt to hold the nose off by adding backpressure when the mains touch down. In our experience, doing so will make the airplane leave the ground again, and then you'll find yourself 3' high with no airspeed and no up elevator left - the result is punching the landing gear through the top wing skin.

BTW, I got the chance to fly a modified PCM L1011 that weighs 55 lbs wet (120 oz./sq. ft. wingloading) and is powered by two AMY 180sp turbines. It was a quite an experience. Straight and level, over 1/4 throttle would have you going 130+ in a heartbeat (the modified airframe is only stressed to 135), but in the turns, you had to come well past 1/2 throttle to keep from bleading off all your speed because of the weight. Also, because of the low thrust line of the engines, any power up resulted in a serious tendency to climb which was even worse if the flaps were down. It was a "busy" airplane to fly, but quite a rush.

Bob