What digital Hitec servos are suitable for QM40? Are many people using these?

I've had success to date with 225s in my Quickies and combat models and would like to stick with them if they have a well regarded digital servo that people are using in QM40.

Hitec makes a Mini Digital in the same case as the 225, the number is HS-5245 MG

These are pretty good servos, I've used them in quite a few planes. The Center MUCH better than the 225, but are heavier.

Other good digital servo choices would be the JR 3421 and Futaba 9650

I have a few of the 9650 that I will be testing soon, but look great on the bench so far.

I forgot to also ask about throttle servos. What is the verdict on the HS81 for throttle servo on Q500/QM40 - have they proven reliable in this application?

Or do you need to go to the next size up to the HS85?

Joe, I have not had great luck with the gears on both the 80 or 81 hitec servos.

In your Q40, is the throttle a fuel pinch off, or does it have a throttle barrel?

I don't even think the 85's can hold up to pinching off a fuel line. One of your Hitec 225's work perfect for a throttle pinch.

Dave,

Our F400 runs with fuel pinch off - no throttle required.

Could you post a photo or two on your set up for fuel pinch off? I have not done one of these set ups before.

OK, a confession. I built a Nelson powered quickie that I used five (5) HS-80 servos in. That's right, one on each flight control surface and throttle. I raced it with those servos for about 45 flights until the airplane was destroyed in a mid-air. No problem with the servos. The wing survived, so I built another fuselage for it but powered it with a ST G-40 and flew it for sport. Flew it a lot with the Tigre, but wanted a bit more power, so I put a Nelson pipe on it and picked up 1500 rpm. Flew it a total of 10 hours with this setup, til I cartwheeled a landing. No servo failure, but at the end of that amount of flying, the servo cases were a little bit sloppy.

I have also built another Nelson Quickie using the HS-81 servos. Also fine.

I think the HS-85 servos would be best for this due to the ball bearing output.

It's important that you not uses these servos if you don't know how to set up control linkages. That means that you use a hole as close to the center of the servo as possible, I drill my own holes in an output wheel. You must also have long arms on each control surface. This is OK, because you don't need much throw in racing. The radio should be set up so that each servo has full rotation.

I really don't understand how so many have had trouble with these servos even on throttle, but it has to be due to poor installation. For throttle linkage, I use about a 2" long piece of music wire with a "Z" bend in one end. I then run a cable in nylon tube to the ball link on the throttle. To connect the two back near the servo, I run both into one or two wheel collars (3/32") and tighten the set screw(s). I only describe this setup because it has worked for me in a lot of airplanes, and who knows, maybe the mass of the wheel collars damped the engine viberation. You just never know. It is easy to adjust.

I can also recommend the HS-225, though the motors tend to wear out at about 160 HOURS of sport flying. Never had one quit in a racing plane though. This is a servo I would use for pinching off a fuel line, or for elevator in a Q40.

Digital servos should be better, only slightly more current drain.

Regardless of what servo you use, do this test. Make a very long wire (4-6") and attach to the servo so you have a very long pointer. Slowly and smoothly move the control stick and observe the pointer. IF it doesn't move smoothly over its range of travel, don't use the servo. If several servos move with jerks or dead spots, then I would suspect trouble in the transmitter control pot. Also test the servo you use by placing a small resistance (your finger) on the output and move. It should also feel smooth and sound smooth.

i use the HS-85MG on the stab on both my my Neme-Q+'s and they work perfect...i only use them on the stab because it is a v-tail design and it doesnt take much tomove one of them...they center perfect and the airplane flys great...i use a 225 on the wing, and a 85bb on the throttle...the setup for me works really well, and i will be doing the same setup on the 2 i have on order as well...

I have also founf that the SL-451 servos work really well for pylon racing...very good servos at a great price

Cole