Originally Posted by Magne

One point to consider is that servos in models with electric motors use a LOT less electricity than similar servos in a model with an IC engine. This means that you can use a much smaller Rx pack, and the additional weight for a separate Rx pack is very small.
Your model will probably not use more than 50 mAh per flight. The 2s Li-po Rx pack will weigh no more than 2 oz. Well worth the added security, I think.
Magne

Magne in my 10 years of flying this is the first I have heard of the above, please can you link to somewhere confirming this, the amp and current draw for servos has no reason to change based on what engine system you are using

Thanks to all those who replied. Seems to be a lot of support for a separate battery for the receiver and servos. I believe I am more inclined to run a BEC off of the flight battery as this model is not wide open to accessing electronics. As an IC build there is no access to interior once the lower wing is installed. I am planning to cut a hatch in the forward cockpit floor to slide the 5s flight battery forward, at an angle, against the firewall. It is going to be troublesome to just hook this up with APPs (75 amp) working under the top wing from behind. An additional battery, while insignificant weight wise, could be a lot of bother. Additionally, I have already spring for an Emcotec SPS in lieu of a safety plug. It probably makes more sense for this to kill everything, rather that just the ESC.

I was really wondering if anyone had any feedback on the servos I was considering? I will look into the Savox servos.

Thanks,

Paul

Originally Posted by Turner2

A servos current draw has nothing to do with the type of propulsion.

The servos are using much more current fighting the vibration of the IC engine trying to stay stationary, than actually moving around.
A typical 8 minutes flight with my 2 meter electric F3A/pattern model takes about 35-40mAh out of the pack. (Compared to a similar model powered by a YS 170, typically 150-200 mAh.)
In my 2.6meter IMAC model (i.e. 100-120cc size) it takes about 120 mAh for a 10 minutes flight. With glow or petrol engines it will be a lot more, even if you are flying exactly the same programme with exactly the same control surface movements.

Magne

That's a very interesting idea and I am in no position to dispute or agree. It is something to think about though.

Unless you are flying the same airframe with the same servos and doing the same routine I don't think you can claim this example is definitive.

Thanks though for your response and giving us something to think about when planning our power systems.

A lot of people have observed this when moving from glow to electric in F3A/pattern.

Originally Posted by Magne

The servos are using much more current fighting the vibration of the IC engine trying to stay stationary, than actually moving around.
A typical 8 minutes flight with my 2 meter electric F3A/pattern model takes about 35-40mAh out of the pack. (Compared to a similar model powered by a YS 170, typically 150-200 mAh.)
In my 2.6meter IMAC model (i.e. 100-120cc size) it takes about 120 mAh for a 10 minutes flight. With glow or petrol engines it will be a lot more, even if you are flying exactly the same programme with exactly the same control surface movements.

Magne

I'm really surprised by this to be honest.

Originally Posted by Paul J. Harris

Thanks to all those who replied. Seems to be a lot of support for a separate battery for the receiver and servos. I believe I am more inclined to run a BEC off of the flight battery as this model is not wide open to accessing electronics. As an IC build there is no access to interior once the lower wing is installed. I am planning to cut a hatch in the forward cockpit floor to slide the 5s flight battery forward, at an angle, against the firewall. It is going to be troublesome to just hook this up with APPs (75 amp) working under the top wing from behind. An additional battery, while insignificant weight wise, could be a lot of bother. Additionally, I have already spring for an Emcotec SPS in lieu of a safety plug. It probably makes more sense for this to kill everything, rather that just the ESC.

I was really wondering if anyone had any feedback on the servos I was considering? I will look into the Savox servos.

Thanks,

Paul

You could also go with the old tried and true NiMh pack for your rec/ servos and hook it up via a charge switch so you never have to remove it.

A 5 cell 2000+ NiMh pack would power 7 5645s for several flights with no issues and you wouldnt need to bother with a hi voltage rec or voltage regulator like you would using a 2c LiPo.

Originally Posted by Arkole Blake

You could also go with the old tried and true NiMh pack for your rec/ servos and hook it up via a charge switch so you never have to remove it.

A 5 cell 2000+ NiMh pack would power 7 5645s for several flights with no issues and you wouldnt need to bother with a hi voltage rec or voltage regulator like you would using a 2c LiPo.

true. and you can just top it off between flights if you want.

Hi guys, Heres my HET ME-163 great flying little plane. Top speed so far on 5s pack is 152.99 up wind to 160 mph with a 4.75 x 4.75 prop on a down wind run. Here are the spec's on it. Amps=98.1, Watts=1776 and RPM=42,300 not bad for a 40 dollar motor.

Keep em flying
raido56/ Herb

Originally Posted by Paul J. Harris

I was really wondering if anyone had any feedback on the servos I was considering? I will look into the Savox servos.

Thanks,

Paul

The Hyperion's are very good servos and as you've mentioned if you use the DH range are designed for use with Lipo's and Life packs. Although not widely known compared to Hitec, Futaba, etc. they have shown themselves to be very good value for money with typically better centering and and more accurate power ratings than equivelant Hitecs. Compared to Savox i'm not sure but when you consider most equivelant Savox servos are almost twice the price i'll stick with Hyperion.

From what I have read, I like the Hyperion servos. Seems that they are used primarily in helicopters, but then, that is where a lot of the higher voltage RC talk takes place.

Biggest problem I am finding is locating a source for them in the US.

Paul

Originally Posted by Paul J. Harris

From what I have read, I like the Hyperion servos. Seems that they are used primarily in helicopters, but then, that is where a lot of the higher voltage RC talk takes place.

Biggest problem I am finding is locating a source for them in the US.

Paul

http://aircraft-world.com/

they are not in the US but shipping wasn't bad for me and seems to be good prices, I ordered a whole bunch of high torque ones for my new 30cc scale, good service and speedy delivery.

http://www.allerc.com/servos-hyperion-c-40_259.html

Pretty sure these guys are US...I've ordered hyperion lipos from them before, they're good.

Thanks, Endlesslag, I'll check them out.

Paul

And yeah, just double checked- They're in arizona.