chrisscammell

Thanks but again, this only tells me what I already know, that trimmers off in un-powered flight is less efficient but faster.

What I need is information about efficiency in powered flight. When the comp' boys are trying to go as far as possible on a litre of fuel, do they fly with trimmers on or off?

Max L/D on an unpowered wing is hands up usually. As you add power into the mix it raises the angle of attack. Releasing the trimmers lowers it again. But does trimmers off create more drag, as it changes the wings profile beyond the optimum.

Then there is speed. Does cruising at 40km/h with trimmers on (clean profile) burn less fuel per mile than crusing at 50km/h trimmers off (reflexed profile)?

Flying faster creates less induced drag but more parasitic drag. Add that into the mix

It's not as simple as saying that it's the same as efficiency in unpowered flight. That power changes the angle of attack and makes a difference. The question is WHAT difference?

Thanks but I understand 'speed to fly' theory for unpowered flight (I have over 1000hrs of free flight on hang gliders and paragliders). What I need is data about speed to fly under power, assuming no wind and level flight.

Does reducing the angle of attack with the trimmers produce more or less efficient flight under these circumstances?

I would like your opinions on which level of trim on a glider will give the most efficiency i.e mpg. This assuming no wind.

I am into getting maximum distance per litre of fuel and need to know which speed to fly at. I am flying a high performance free flying wing with a glide of 9:1. I have fitted it with paramotor risers with trimmers.

Should I be flying hands up or trimmers released to get maximum efficiency?

My thinking is that the glider is 'cleanest' at hands up trim and that releasing the trimmers, although giving more speed, will create proportionally more drag and therefore reduce efficiency.

Would appreciate your thoughts?

Just bought a Pap Ros 125 secondhand but the harness is too big for me. Anyone want to swap their medium for large? Or you can buy my large for £175. Excellent condition.

This is the low hang point harness and I am looking for the same. Thanks.

I can be reached on 07988 691626. Located in Lakes but willing to post.