ok, i have some experience using flaperons (mixed with elev).... it works well, the only downside being a little mushy controls on landings

i wanted to use this type of a setup on my DF jet for obvious reasons (to slow it down on landings) BUT then i read a post about using spoilerons -being much better for landing a jet...... it seems that the jet lands much better in a "nose high" attitude due to the spoilerons (up 10 deg) and they slow the plane down....

can anyone explain to me why decreasing the wing lift would help landing the jet?

if someone uses this type of a setup pls let me know

thanks, Vasek
BTW am still searching for a set of plans for my BVM Ultra Viper... anyone?

The more lift you kill, the more thrust you can use on landing. In Turbines, that is a blessing due to throttle lag.

The setup you mention is VERY common amongst Bobcat owners. On my Bobcat I originally used flapperons when the aircraft was being flown by a RAM 500 ... but when I moved up to a P120 I found that landings with flapperons were very tough at my home field because the much higher residual thrust of the P120 (sompared to the RAM 500) combined with the steep approach angle to clear the trees meant that the aircraft was always coming in too hot. By putting the ailerons up rather than down, the resultant nose high attitude of the aircraft allowed the underside of the wing to produce much more drag so that I could slow the aircraft down more easily and even carry power on final(s).

As Sean has pointed out, being able to carry power during the landing has definite advantages for turbine powered models - turbines tend to spool up much slower from idle than they do from e.g. 1/4 or 1/3 throttle - so if you can make your approach under higher power then you get a quicker response if & when you need to add more power (e.g. for a go-around).

A minor downside of putting the ailerons up is that this raises the stall speed - so if you are used to the stall speed of the model with flapperons, then you switch to putting the ailerons up rather than down, you should probably add a few knots safety factor until you get used to the new setup.

Gordon

The spoilerons do kill some of the lift of the outer wing panels, but you compensate by increasing the angle of attack of the wing..ie more nose up...

thanks guys, i'll give it a try

Gordon, would the 10 deg up seem as a good starting point?

Seems like a reasonable starting point to me, but I guess that would depend on the particular aircraft and its aerodynamic characteristics. I'm no aerodynamicist, so you may want to try posting this question in the aerodynamics forum if you want a more definitive answer.

Gordon, i did start my question in the aerodynamics forum but had no success there....

guess i'll have to experiment, i will try it on a Patriot first before trying it on my DF jet

thanx for helping,
vasek