johnfly

just got a used h9 cap 232 ..... 73" wingspan, 1.20 size.... but the previous owner kept the motor. I have a saito 1.5 wanting a home and the two seem made for each other.... so i proped up the tail until the wing incidence was 0 then checked the horizontal stab...yep its 0....... set the thrust angle to 0.....then i put the cowl on and the backplate for the spinner was a good three eights of an inch above the spinner.... should i just align the spinner to the cowl or more specifically how many degrees downthrust should it have??? I called horizon and the guy said..........."aaaaaaaaaaaaaa well ya that sounds pretty close........pause ......... ya probably anywhere between 1 and 3 deg......." WOW thks for the hlp....sorry to bother u...............
does anyone know what it shoul be???????
thanks. JB.

rmh

On the CAP-- NO downthrust is best - The model has "effective" downthrust aplenty.
put in some right tho - not critical say - 1/2" total difference in prop tips measured from vertical fin to each prop tip when prop is horizontal .
This is NOT critical -just insures you have right -not left thrust.
These models run heavy so you may experience it tucking on vertical extended climb.
This is due to speed bleed off .
Don't bother screwing with thrust line to correct this.

johnfly

I kinda figured that it was 0 or maybe a hair dn. but the thing that really bothered me was everyone telling me to just line it up with the cowl. that just made absolutely no sense to me at all....... I will leave it at 0 and fly it and then if it needs a bit i will tune it in then later adjust the cowl to match the motor......
thanks i guess i was just wanting to hear it from another modeler....as for the right thrust, that is built into the firewall..and it has plenty!!!! thks again ..

Geistware

My Feedback: (16)

I wouldl recommend a little up-thrust if it is like the 33% model.

rmh

If power is sufficient - Up thrust is not required.
The up thrust is just compensation for loss of speed (climbing).
almost all ARFS loose speed climbing -this changes (reduces) trim drag-so the model tends to pitch to belly.
Our own CAPS run 0 upthrust -
We did that H9 73" model w/ZDZ40 when the kit first came out - vertical trim change was not needed .
We also did a number of lighter 80 " models -and the 33% (still have one of those) and the uptrhust thing will show up if you run less power
That is - they pitch to bottom as speed bleeds off.
Bottom line :
If you have enough power to hold constant speed - the thrust problem goes away.

Geistware

My Feedback: (16)

I have a 24lb H9 Cap with a BME 102 swinging a 26x10 propeller 6000 rpm.
Doesn't seem to slow down on up lines with me.
I have tried going vertical from a harrier (can't torque roll) and it still pitches to the gear

rmh

Thought that question might follow.
Basically - you have to consider trim for a given speed in level flight --which matches vertical speed
That consideration does not work for hover recovery.
The model has the thrust line way above the centre of drag -which is about the wing location.
so add upthrust if you like - I don't find it helps in this situation .
I run a 26x10 Mejzlic or MenzS at 6600-6800 and get pretty much same thing you mention - you simply have to fly the CAP away from the hover with some UP input.
My plane is 23 lbs -but being up at 4350 ft - I have a worse condition.
CAPs simply ain't like models with thrust lines closer to main drag (the wing)
If you had a model such as a Citabria (high wing) with similar power for hover etc., you would likely note it pitches UP - not down.
Make sense?