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Basic Pitch Setup

3K views 5 replies 3 participants last post by  Uba Tracker 
#1 ·
Hi guys, this is a job I seem to have done a hundred times but this time round it's not playing the game. I've just finished building a Trex 450S CF and have gone about setting up the swash and pitch. Usual procedure, get the servo arms as close to level as possible with the throttle at mid stick and then tweak it with sub trim. While at mid stick and level set the blade pitch to 0°, so far so good. Now crank the throttle to 100° and what do I find 7° maybe 7.5°. No worries, dial the swash mix up to 90% to achieve 10° at full throttle only to find that mid stick now registers 2.5° - sigh, at least it's consistant. Next plan, drop the swash back to the original 85% and restore the 0° at mid stick, sweet, now crank it to 100% throttle and lift the pitch to 10° by means of linkage adjustment, all good, 10° achieved. Drop the throttle back to mid stick and wadya know 2.5° pitch, FAAAAAAAAAAARK!!!!!! It seems I can't alter the max pitch without affecting the mid stick. Geez I know this can be fiddly but what gives, what am I doing wrong this time?:confused:

Ta lads

Harry
 
#3 ·
With everything back to basics, ie. 0 pitch with arms level and 7 degrees +ve at full stick, what -ve pitch do you have at dead stick?

Is it 7 degrees -ve?

If so, my recommendation would be to go out another hole on the servo arms to give you more throw.

Your process is spot on, so it has to be mechanical. I hate adjusting swash mixes, etc. On a trex, you should be able to get it right mechanically and keep the radio setup very simple.
 
#4 ·
Thanks for getting back to me lads. Chris, the -ve pitch is around 7° as well so at the very least I'm getting equal travel in both directions. The confusing part, for me anyway, is why the swash mix is affecting the mid stick pitch value. My understanding is that altering the value of the Swash Mix (SM) simply increases or decreases the maximum available pitch within the confines of the mechanical setup, without affecting the mid stick or 0° value. I had also thought of moving the linkages further out along the arms and will probably end up doing that if I can't resolve it electronically. Just for fun I'll set the SM to 100% and adjust the pitch to whatever I can reasonably achieve and focus on striking an acceptable balance between the mid stick and max by playing with the SM.

cheers

Harry
 
#5 ·
Hi Harry,

Yeah, I am personally a mechanical setup guy. Given that you are getting a good equal pitch swing, your setup is clearly pretty good, just not enough travel.

See how you go with the radio setup, but longer arms / further out on the existing arms will definately get you there.

I can honestly say, with most "good quailty" kits (Align, etc), I have been able to achieve mechanical setups that are pretty spot on, if I have followed all of there linkage length and servo arm setup recommendations. What servos are you running? Do they have a less than a 60 degree throw in the default setup? Is you radio set with all travels at 100%, etc? Is the pitch curve linear, 0 to 100%?
 
#6 ·
G'day Chris,

Yeah look I'm with you all the way with thumbs up for the Align set ups. I built my 550 following the instructions almost to the letter and aside from advice regarding the 3G setup it was perfect out of the box. Anyway back to the 450, I'm running Hitec HS65MG's exclusively and thus far have found them to be as reliable as the day is long. I'm not certain of their operating range but I believe it's 60°. Fingers crossed I can wring some more pitch out of it as I plan to shoe horn it in to a Hughes MD500 so a bit more lift won't go astray.:)
 
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