Slow stick adjusting downward motor thrust?

[Monterey10]

When I apply throttle, the slowstick turns straight up. I believe that the motor needs more downward thrust. I'm using the plastic brushless stick mount. The mount is not adjustable. I suppose I could use washers behind the motor. . One post said to put a wood extension in the aluminum tube and trim it for downward thrust.

I'm hoping that the Watt audience can explain to me an elegant way to create downward thrust on the slowstick.

[JetPlaneFlyer]

CG too far forward will also make pitch up when under power much worse.. You might want to try edging the CG back and see what improvement you get before adding more downthrust.

Steve

[flydiver]

If you want elegant then look through this:
Slow Stick Adjustable Motor Mount Kit

But frankly I'd just use the washers. Simple is often better.
If you have a BIG HONKING FAST motor in it the undercambered wing will really want to climb with a lot of throttle. The cure for that is throttle control (your thumb).

[Bill0]

Originally Posted by flydiver

If you want elegant then look through this:


But frankly I'd just use the washers. Simple is often better.
If you have a BIG HONKING FAST motor in it the undercambered wing will really want to climb with a lot of throttle. The cure for that is throttle control (your thumb).

I have the adjustable mount mentioned. they work really well. Takes a little tinkering to get it just the way you want it, but get the cg right beforehand.

[Rockin Robbins]

I don't know what kind of motor you have. Mine has unlimited vertical capability, accelerating all the way when it's wide open. You may well have the same.

I have about 5º down thrust on mine. Keep in mind that your downthrust is only tuned for one specific speed. Below that speed your nose will drop. Above that speed your nose will rise because you have a high lift, high drag undercambered wing. I tune mine for level flight at about half throttle.

One way to reduce that climbing habit under severe power is to use two front wing mounts or two rear wing mounts to put the wing at 0º incidence in relation to the fuselage and horizontal stabilizer. Many have done that and had some success.

I just figure a Slow Stick is a Slow Stick. I'm not going to turn it into a P-51 because then I'd miss my Slow Stick. I may put a Stephens Soar Stick wing on it at one point to make it zippier and have better glide characteristics at the same time. But I'll always enjoy flying it the way it was designed.

[Bill0]

Originally Posted by Rockin Robbins

I don't know what kind of motor you have. Mine has unlimited vertical capability, accelerating all the way when it's wide open. You may well have the same.

I have about 5º down thrust on mine. Keep in mind that your downthrust is only tuned for one specific speed. Below that speed your nose will drop. Above that speed your nose will rise because you have a high lift, high drag undercambered wing. I tune mine for level flight at about half throttle.

One way to reduce that climbing habit under severe power is to use two front wing mounts or two rear wing mounts to put the wing at 0º incidence in relation to the fuselage and horizontal stabilizer. Many have done that and had some success.

I just figure a Slow Stick is a Slow Stick. I'm not going to turn it into a P-51 because then I'd miss my Slow Stick. I may put a Stephens Soar Stick wing on it at one point to make it zippier and have better glide characteristics at the same time. But I'll always enjoy flying it the way it was designed.

I guess I should have been more clear, your right about adjusting for cruise. Mine is at about 1/3rd throttle for level flight, after that it starts to climb, until it's wide open and going straight up...............outta sight. Throttled back it will still fly and walking speed.

[Rockin Robbins]

Now if you adjust more downthrust in you'll be level at a higher cruise speed but you know that. The other thing you can do is minimize the mechanical advantage your wing has.

If the center of lift of your wing is too far behind the center of gravity of your plane, you're maintaining level flight with up elevator, which rotates the plane up around the center of gravity. As you move that center of lift forward toward the center of gravity (or move the CG back), it has less and less mechanical advantage to rotate your plane upwards, kapeech? Then your elevator can stay flat and not have to force the nose up.

When you reach the point were the center of lift and center of gravity are at the same point your plane will no longer lift the nose with the application of power. Unfortunately the plane will be stark raving crazy at that point and you won't be able to control it without a gyro. It would have no inherent pitch stability at all, but your pitch up on power problem would be gone. Unfortunately your plane would also be a smoking hole in the ground...... It's always something.

[Monterey10]

I'm pretty sure I have a combo of Large motor and poor CG. I've put a smaller motor in and will try to do a better job on the CG. I have a GP CG finder to use now.

THanks for all of your input.

[Rockin Robbins]

Good deal! Have fun with that Slow Stick! Can there BE such a thing as too much motor?

Even the military doesn't think so. A carrier project for near the end of WWII was a special Corsair called the F2G. It had one purpose: take off quickly and get to altitude over the carrier fleet as soon as possible. With a massive Pratt & Whitney R-4360 twenty-eight cylinder, four row radial engine it had 50% more takeoff power than a standard Corsair. At 167 watts per pound it had pretty good performance.

Unfortunately, with the obscene amounts of power came severe restrictions on how the plane could be flown. For instance there was a maximum dive angle. If you exceeded that you might as well try punching out and testing out that parachute.

Only 10 F2Gs were ever built, two of which went on to air racing careers. I had the chance to see and touch one of them while it was in many pieces during restoration in the middle 1980's. That particular plane is now in flying condition and after having been raced again is in the Fargo Air Museum.

[philipa_240sx]

Once you get your CG correctly set and any trim issues sorted, there is something else you can try:

Throttle to elevator mix. It usually only needs a bit... around 5-10% down elevator at full throttle. But be WARNED, this is NOT a substitute for a properly trimmed plane!