ORIGINAL: Fortune7
ORIGINAL: olnico
ORIGINAL: Fortune7
Oli,
This is re-posted from the Weatronics 'Gigacontrol' thread as you correctly suggested.
I really should go back into this thread and do my own research, and will do when I have time in the next few days. However, until then here's my issue: I have a Eurosport with 2 x servos (8611s) per single elevon, previously matched using a Powerbox SC-12 and 35/72 Mhz radio. Dave Wilshere recommended this setup as it gave a more 'locked-in' feel of control when he did a review in RCJI for the Eurosport about 4 or 5 years ago (!) Now I am converting to a Weatronics 2.4 receiver which could mean I can remove the Powerbox providing the servo power loads don't exceed the receiver's 10 amp limit. Despite the Weatronics' programming capability to match the servos without the PB, I am now considering reverting to one servo per elevon (as indeed most ES owners have) but would like to have a better understanding of the likely servo mechanical and electrical loadings with that setup. Assuming the loadings are within the servo and receiver capabilities, it would be good to revert to a simpler and lighter setup. Two extra 8611s put the balance point further aft so I have cmpensated with nose-weight and it would be good to shed this if possible.
So, any pointers or thoughts will be appreciated.
Cheers, Andy
Please have a quick look at post 1 to 5 so that you know what we are talking about.
Then send me the following information for each flight control:
Average chord, span and horn distance to the control axis in cm, distance from the servo axis to the control axis in cm.
I will compute the data and post it here.
OK, Oli, here are the measurements for each Eurosport Elevon:
Average chord: 11cm
Span: 60cm
Horn distance (control axis to ball link): 4.2cm
Distance from servo axis to control axis: 9.5cm
If you can run these numbers and let me know I will also use the spreadsheet and see how you got there. Remember, I'm trying to evaluate use of a single 8611A servo per elevon, rather than the two I have now. I would think 120 mph average and 140mph max is realistic for my flying style.
Many Thanks, Andy
Oli or Harry,
I computed my numbers for the Comp-arf Eurosport's elevon(s) on the spreadsheet: Xs=9.5cm, Yc=-4.5cm, Rs=+/-40, Rc=+/-20, Vmax=150, Cavg=11cm, Lavg=60cm.
Now, the 8611 servo has 220oz/in of torque, and my figures produce a Tsmax of 211oz/in, so there isn't much safety factor at max speed and throw, but then these conditions seem unlikely for smooth, conservative flight.
At a stick deflection of 30%, the torque needed is only 80 oz/in, so do you think this setup is realistic? I haven't yet measured static servo currents at these torques.
Cheers, Andy