Adjusting the prop shaft angle via radio/servo
05-19-2007, 01:02 PM
#1
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Adjusting the prop shaft angle via radio/servo
Is there any tunnel hull modellers who have used a system to adjust the prop shaft angle during a run, if so are there any details about. Thank you anyone...
05-19-2007, 02:53 PM
#2
RE: Adjusting the prop shaft angle via radio/servo
It requires the servo to be modified so it can spin continuously either direction and a driveshaft attached that goes to a fine thread jackscrew that is tapped into a hinged motor plate.
A standard servo with an arm is not shock proof enough for it to be used as the brace.
I've never experimented myself but have seen how they are made.
A standard servo with an arm is not shock proof enough for it to be used as the brace.
I've never experimented myself but have seen how they are made.
05-21-2007, 03:37 AM
#4
RE: Adjusting the prop shaft angle via radio/servo
This is the only other method I can think of that can reduce the shock and travel. Its just a set of pivot arms attached to a moving motor plate.
One of the biggest stumbling blocks is the steering linkage being able to adjust with it, which can be minimized by lowering the steering to the pivot point, but still needs to be compensated as it moves.
Trim changes only involve a range of plus or minus only a couple degrees, so some type of reduction has to be involved.
Another variable that becomes involved with the changing degrees is motor height which can also be considered critical.
The optimum pivot would use the prop as the fulcrum point in relation to the rear of the sponsons.
One of the biggest stumbling blocks is the steering linkage being able to adjust with it, which can be minimized by lowering the steering to the pivot point, but still needs to be compensated as it moves.
Trim changes only involve a range of plus or minus only a couple degrees, so some type of reduction has to be involved.
Another variable that becomes involved with the changing degrees is motor height which can also be considered critical.
The optimum pivot would use the prop as the fulcrum point in relation to the rear of the sponsons.
05-21-2007, 06:41 AM
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RE: Adjusting the prop shaft angle via radio/servo
Cheers bud for the info, it seems it's a difficult one to overcome this with all the other paremeters to consider. A friend of mine, who is an engineer suggested using a cam arrangement. Have you ever heard of this one...?
05-21-2007, 02:34 PM
#6
RE: Adjusting the prop shaft angle via radio/servo
Yes a cam would allow fine changes with just one control arm. The mount would have to be spring loaded to the cam to hold it tight, but a long control arm on the cam could compensate for any high-drag that the cam would put on. Probably a more positive means of adjustment than the other two approaches, due to less slop. Coarse adjustment could be made with spacers at the transom. Thrust points would force the cam to be located at the least optimum location at the bottom of the mount, and hinge point at the top - which exaggerates thrust angle changes. Aside from machining the cam itself, probably the simplest most tidy approach mechanically.
