Wanting to learn more about HV servo setups

[Ohio AV8TOR]

I am wanted to learn more about the setup when using HV servos and I would like to hear your opinions, setups and things you would do different the next time.

About the power supply; In my thinking there are two main approaches, use a separate BEC and dial up the desired voltage or use a separate 2S Lipo battery. I see the separate 2S lipo as being a little more safe if you should have an ESC problem or battery ejection as you can still dead stick it in. The flip side is you have to stay on top of that second battery charge status. What is the most common method or your favorite?

So what about the exact voltage, if you use a 2S Lipo the full charge voltage is not 7.4 it is 8.4. The servos are rated for 7.4v is this a problem? If not a problem and when using a sperate BEC what is the desired voltage setting for the BEC?

Please tell me your feelings on quick versus slower servos, say 0.08 vs. 0.18 speeds? What do you gain or loose? Is there a twitchy feeling to flying with fast servos? Would it be safe to say that precision flight would benefit from slower and 3D from faster?

For me right now for new 60" I am looking at the Airtronics 94820 which is slow, powerful and from what I hear bulletproof at 90 in/oz @ 6.0v and 0.18sec/60° @ 6.0v. This would make a pretty straight forward setup. Then there is the HV servos such as the 7245's 0.11sec/60°, 88.88oz/in @7.4v

 

[djmoose]

The reason the servos are spec'd at 7.4 is that is close to what you'd normally see under load even off of a fully charged lipo. However, let's be honest...you're going to get a higher voltage then that just running 4 digital servos...however it could possibly drop down to 7.4 during a pop-top or something with full deflections. I assume 7.4 is a safe spec for torque and speed ratings so you'll know you're getting at least that when the pack is under load. That being said, I would imagine that all HV servos are ok at 8.4.

There are people that use BECs and set them to 8.4, some set them to 7.4. I know AJ likes BECs in this situation because you don't have a chance of loosing performance through a flight or across multiple flights in a day.

Will a non-professional casual flyer notice that difference? probably not. I do not in my 74.

For my 74, (and planes I REALLY care about) I try to use separate packs. 74, Sebart Pitts Python, 89, Top Flite Staggerwing, etc etc

However, for my 103, I'll be using 2 3S packs each with their own BECPro probably set at 7.4. (maybe 8...haven't fully decided yet)

I'm interested in hearing everyone else's thoughts.

 

[Ohio AV8TOR]

Well I am two steps closer. Just ordered my 7245's from Tower tonight. Hard to be the package price plus $30 off "and" free shipping.

Moose that is interesting about AJ using the BEC to have constant voltage on every flight. In the hands of the masters they can feel that stuff just like our golf clubs