I'm using 2 dynam micro servos on a 1909 wright military flyer.My concern is that servo arms don't seem to move control surfaces far enough.Don't know how many degrees of travel supposed to get from cunnards or rudder,but what there is seems to be a little shallow to me.Is there any way to extend this travel length?Do all micro servos pretty much travel the same radius?Are there micro servos that travel a longer radius.Is there some kind of linkage set-up that would allow control surfaces a bit more travel?
Longer arm on servo
Shorter horn at control surface
Digital programmable servos... Many can be programmed for 180 deg instead of the standard 100 to 120 deg.
"ATV" (adjustable travel volume... sometimes called endpoints) in computer radios.
The computer radio can be safely programmed to 120% travel (rotational... often about 110% actual response at the surface) with most servos.
Note that Parkzone ultra micro servos can not be pushed past 100% (100% reference is Spektrum DX6,7, 8, 18 default travel) safely.
"full flying" control surfaces (no fixed surface) need appx 1/3 the deflection angle of the conventional fixed + moving control surface. 10 deg (each way) is a lot for a "full flying" Canard such as on a Wright Flyer. The rudders may still need up to 30 deg (each way) available due to being so close to the main wing and CG.
Generally with servos - it's best to stay with the standard lengths - why ? Torque and stress on the servo. Micro servos especially cannot take increased loads and strip out very easily.
The Tx EndPoint Adjustment (EPA or ATV as some call it) ... is in my opinion a dangerous item when called to EPA more than 100% ... why ? If you have combined surfaces ie elevons, ailervators etc - pushing EPA to 120% can lead to servo trying to move further when other command made simultaneously. This leads to burnt out servo motors. Ask me how I know !!
The best way is geometry ... moving clevis OUT on servo arm, IN on control surface horn.
I'm using 2 dynam micro servos on a 1909 wright military flyer.
My concern is that servo arms don't seem to move control surfaces far enough.
Don't know how many degrees of travel supposed to get from cunnards or rudder,but what there is seems to be a little shallow to me.
Is there any way to extend this travel length
?Do all micro servos pretty much travel the same radius?
Are there micro servos that travel a longer radius.
Is there some kind of linkage set-up that would allow control surfaces a bit more travel?
Much more information available under sub sections
"Glitches & Jitter in Receiver, Servo & ESC - Causes and Cures"
"Servo - Alterations, Calculators, Databases, Leads, Repairs, Convert to an ESC or winch & FAQ."
"Radio Systems, Accessories, Alterations and FAQ" at Alan's Hobby, Model & RC FAQ Web Links
Re-read the instruction sheet and found where the designers recommend the canard throw to be 7/16ths up and down measured from the leading edge of the canard.Got out a piece of paper,protractor and small angle and drew this full size the way I read this is the canard throw works out to be about 25 degrees.That looks a little steep on paper.Cannot raise leading edge of canard to that degree anyway as the trailing edge would contact the pushrod
Post #6 +1
- FAQ : Throw, 100% Tx setting is best, 125% is mechanically poor[/URL]
I didn't read that thread entirely that way, here's a quote from one of the better posts in the thread:
By increasing servo throw and using a shorter servo horn and/or longer control surface horn you can increase output force and reduce stress on the servo.
While there are trade off's (arent there always) increasing throw to greater than 100% is often a better option for getting more deflection compared to doing it mechanically with longer arm or shorter horn, because it maximises the force transmitted to the surface and minimises the stress on the servo gear train.
Like most things it needs to be done with some caution and knowledge of the potential pitfalls.