Winter build project: Wolfgang Matt’s ATLAS

With many thanks to David for his snake tubes and for the chance to look around his workshop & a lovely chat, I'm now back on track. The servos should arrive early next week, for anyone who's interested I ignored Jon's suggestions, sorry Jon, and went for these: JR NX588

I'm planing of deviating a little from Mike's layout and will run the two elevator control rods down the center and the rudder will cross over half way down the fuselage.



Could anyone tell me what the maximum elevator and rudder control surface deflection in degrees is likely to be on this type of plane, I'd like to get reasonably close with the servo geometry so that I maximize the servo travel.

MikeSeale wrote: ...I got my 63mm wheels from SLEC

Any reason you went for 'tundra' tires Mike? The wheels on the plan are 56mm.

Excellent choice of servo Chris, was just trying to save you an extra £6 each, Mike could buy a servo and a half for that extra cash You will be all set if you want to go Xbus in the future too!

Chris001 wrote: Any reason you went for 'tundra' tires Mike? The wheels on the plan are 56mm.

I used 57mm wheels on the BA and feel that slightly bigger diameter will reduce the bending loads on the retracts on those less-than-perfect landings on our grass strip. If we were landing on perfectly smooth asphalt I would keep them smaller.

Oh, and one other possible reason...the smaller wheels from SLEC were a tight fit on the JetCraft retract axles and needed a little work to open up the hole. The 63mm wheels are a perfectly smooth fit. I'm sure I just got unlucky with the first order, and might buy some smaller ones later to try out

JonTappin wrote: Mike could buy a servo and a half for that extra cash

I resemble that remark. More importantly, my 4 servos cost less than one of Chris's. One of us will have a very eggy face if the model crashes due to a servo failure!!

Hi Jon, nice to have your approval... for once the servos have slightly better specs then the versions they are replacing, although not as fast or as light... or as cheap as Mike's so he can keep that warm glow of content about his choice of servo. I would eventually like to move away form Spektrum and JR would be a strong candidate, although I'm also keeping a close eye on the Frsky Horus. Either way, hopefully a perfectly capable servo for my intended use.

I've just measured the throws on the Blue Angel Plan:

Elevator: 18º up, 14º down
Rudder 25º left, 25º right

20 deg should be ok for elev but you will need as much as you can get for the rudder, before it hits the elevators probably 40 deg ish.

My BA has about the right aileron and elevator movement (according to the plan) but, like Jon suggests, I have given myself as much rudder throw as possible. This can be measured on the Atlas plan by looking at the angle that the elevators are cut at the root. Probably about 40 degrees each way.

Thank you gentleman.

Another question for you, standard servo travel is 60º, but you can increase this by setting the servo end points beyond this in the radio. Should you do this to maximize servo resolution and travel? Or is that servo travel beyond the 60º to allow for trim and mixes that might take you outside of that 60º range?

Not sure what others do, but I have my radio set to -100/+100 for the servo travel at first and adjust mechanically to get the throw I need. If I can't get the right movement I adjust the end-points up or down. I've never owned a programmable servo so for me it is all done in the radio.