Large Model Association Forum

Hi
Could anyone confirm if hitec servos 545bb has enough power for the wing aileron, I have one per wing fitted, the Gilles is a 1/3 scale 98 inch span with a 3w100 engine.

Thanks Brian

this is the spec for that servo , but it also depends on how much mechanical advantage it has ,, but my first thoughts are NO , if it were me i would put a 5645 and use a LiFe battery


Modulation: Analog
Torque: 4.8V: 61.1 oz-in (4.40 kg-cm)
6.0V: 76.4 oz-in (5.50 kg-cm)
Speed: 4.8V: 0.22 sec/60°
6.0V: 0.17 sec/60°
Weight: 1.57 oz (44.5 g)
Dimensions: Length:1.56 in (39.6 mm)
Width:0.77 in (19.6 mm)
Height:1.41 in (35.8 mm)
Motor Type: 5-pole
Gear Type: Plastic
Rotation/Support: Single Bearing

noooooooooooooo, it will fall out of sky faster than it went up. As rule of thumb in 100 cc aerobats you need all metal geared servos, 20 kg and above for that model ideally you need 2 servos per aieleron of 15 kg each, say jr 8511 or equivelant or if you are only going one servo you need 25kg jr 8911 or equivelant. this will give plenty of authority. all other surfaces need the same sort of power. I had a 100cc giles 202 my set up was 2x jr 8911 per aileron, 2x jr 8511 per elevator and 3x jr 8511 for the rudder through a powerbox champion. you need loads of capacity for a 100cc 30% scale aerobat.

Thanks for the replys, only just getting back into model aircraft after 30 years, and having bought this I thought that the servos were under sized so will look to replace them.


Thanks Brian

Hitec HS-7955TG servos at 6 volt now being installed

Thats plenty, just watch linkage slop and also dont use their standard plastic output arms, not up to it im afraid.Alloy jobbies are best for that application with 3mm ball links and 3mm allthread as a good standard, at least you can be assured that the control department is sound and wont let you down.

Do you use a step battery supply for the servos, rather than just through the reciever, if so what is the best set up

Thanks

Depends on your radio being used.

If futaba then you can use the new high voltage RX

Another option is to look at a power box. you will use two batteries duel regs etc all in one unit.

Some links here of one which would suitable.

http://www.powerbox-systems.com/en/prod ... ution.html

The giles has a 3w100 twin in it, just found that there is no spark, anyone know how to test the ignition unit on these.

Thanks Brian

Spark problem was ignition unit, just fitted a rcexl unit, anyone know the correct degrees tdc for the engine timing.

Thanks Brian

Static timing for Rcexl ignition is 28 degrees Before Top Dead Centre. The ignition unit has built in auto advance so you don't want to set it more advanced than this stationary. If you find that the engine kicks back too much when starting you can retard it a bit but it should be OK

Thanks for that Peter, I will set it at 28 and try it.

Regards Brian

Timing setup and engine running spot on. Getting close to flying it soon.



Brian