My new performance model has a tuned pipe -which has an exit turned 45 degrees and the exit is turned to the right (looking from above) -
This exit point is aproximately 1/3 the distance from the cg -to the rudder hinge line
In a hover - will the force of the exiting gasses , EFFECTIVELY act as added right rudder ?

Well, since the velocity of the exiting gases is not very high and their mass is pretty small, I'd have to say that the side thrust component it is producing would be negligible compared to the weight of the plane. Is this a baited question???[&:]

Say, has anyone built a turbine scale model of the AV8B Harrier with full VTOL capability yet? Sorry, the question just popped into my head. I'll go ask in the jet forum.

Not baited at all- in a hover the forces required to shift the model are pretty low - the prop is a flywheel sure but in playing with foamies pinced lightly between my fingers and "hovering "them --I found that very small trim changes in the TX made big changes in how th model balanced in this suspended position..

It may also add a slight (minute) rotational force.

Off topic-

Dick, how much did your Showtime/Evolution 1.6 experiment weight? Wing loading and power okay for pattern (intermediate)?

Thanks,
mike

10.25 lbs --with the CF pipe -10 flat - it is a terrific pattern plane -except the pattern die hards may poo poo it
Just set it up with reduced throws JR9411 servos on 6 v so you get best resolution on servo setups
Mine was very stable but you can not fly it accurately wide open -you need to use a throttled back approach and just feed in power as needed.

Do something to measure the psi's and you have a working figure to deal with, perhaps adjusting the size of the exaust to a smaller/nozzle and/or rigging it up to move a servo and/or seperate prop can do the trick as well if you cannof find sufficient thrust. If I get the gis of the dialog right, it sounds like you have a very light airframe, so even a minute thrust may do the job, be it not entirely responsive in a practical sense if it was heavier.

I ran some numbers and got:
For a 1 cu in engine at 10,000 rpm , 4 stroke, roughly intake 100 cu/sec.
For a 1/2" dia exhaust and exhaust temp of 1000F the exhaust velocity is 130 ft/sec
The flowrate is .005 lb/sec. Thrust is .02 lb. At 45 deg the thrust component in the direction 90 deg to flight is .015 lb.
If you shim the enginge 3 deg right the right thrust is 0.5 lb for a 10 lb thrust engine/prop .
A 30 sq inch rudder with 20 fps prop wash blowing on it can generate about 0.1 lbs of side force.
That says the engine right thrust may overwhelm the rudder. I guess the prop wash velocity is a lot more than 20 fps. Rudder force goes as propwash velocity squared.

So exhaust thrust is pretty small. A few degrees engine thrust is relatively large.

That's a fair bit of theory - I have never found engine side thrust setups to much good - I do end up simply trimming rudder a click usually -from "dead on" Also as a SWAG -2 degrees on most areobatic setups seems "OK" neither too much or whatever .
This setup seems to be quiet solid in holding verticals -I would guess now and flow it a while -that the actual additional side thrust is pretty small
my electrics are the only ones where I can really test the thrust thing accurately -as I can hold them and do trim tests as I hover em
The math is interesting tho thanks!