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Ever Feel like we are over doing our servos?

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Ever Feel like we are over doing our servos?

Old 08-28-2020, 07:39 AM
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Default Ever Feel like we are over doing our servos?

SO, I'm surprised as Im sitting here with a ton of very large birds thinking about servos for my latest bird.

I don't buy a lot of used planes, but in the last year I picked up a 1/2 sale 112in Christian Eagle with huge ZDZ210 in it, I know this plane has been flying for 4 years now I as I personally know the old owner.

I do a inspection and find he has some 300oz Hobby King servos for each tail surface and these surfaces are not small 22 wide by 14in thick. I freak out and replace with 1000 oz futaba A500 servos

I got a cool 20 year old 90in Byron AT6 built by Top Builder for Discovery Channel a long time ago with a G62. I go throw it and every servo except one was a 4.8v only futaba with max of 45oz, I replaced with futaba S3071 145oz servos 6.6v

5 years ago I picked up a CAI Razor (think BVM Bandit) with turbine and a hole bunch of 4.8v 55oz old futaba servos, I know this is all they had at the time these planes where built but these are 200mph jets and anyone building a jet today would think you crazy for putting a 55oz servo on anything except an air retract valve.

This week I picked up a 1/3 Scale Balsa USA D7 with a DA85 running HS645 servos on the elevator (130oz) and HS5645 on rudder and ali (166oz) at 6.6v.(I only use life packs not a lipo fan as I hate pulling battery's to charge. them. One of the HS645 on elevator is not working correctly ie not going back to a center well. So I replaced them with some futaba S9177SV as I had 2 new ones sitting on my shelf. but at 512oz vs the 130oz that was in there Im starting to question my self. Im sure these servos are over kill but now should I replace the HS 5645 in the wings also?

There used to be this great Blue Bird servo torq calculator online that pulled its calculator off as there was some comments about it being used to calculate drone servos or full size aircraft servos. I don't really know, but it was amazing to see how little torq is need for a huge control surface like this D7 has but with a max flying speed of 70mph there is little force needed according to the calculator.

Heck my first giant bird is a one off 160in C130 with 4 huge electric motor set up with my home made 16X12 X 4 blade props that can pull 100feet straight vertical on take off, I putt S9177SV on every control surface as at 78 pounds I had to get it LMT1 Certified and didn't want any question as if I had enough servo power even thought that old Bluebird site said I would of been safe with HS645 on all surfaces due to there small size and top speed of 85mph of this plane.

As every few months there seems to be a new 300-500oz bad ass servo with a cost of upper $140 each, do we really need such powerfull servos on a 1/3 scale D7 or is it because us jet guys just want the best of the best, Im feeling lost on what to do with this D7 which is crazy to me.

Ill be honest, I have never flown a WW1 plane. So this D7 will be my first




Last edited by mikes68charger; 08-28-2020 at 07:44 AM.
Old 08-28-2020, 08:50 AM
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LOL yea, that D7 won't need huge servos.

Old 08-28-2020, 12:08 PM
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I honestly think we or over servoing lots of times. Back when the Goldberg Suhkio came out I flew one with a webra 1.20 and it had one 45oz servo to drive both elev halves. I even mounted a Sony handy cam on top of it and flew it around with an all up weight close to 10 lbs. The big difference now days isn't so much deflecting these big surfaces as much as it is holding them. It takes a lot of centering strength when 70% of your tail is move able. Another factor is the amount of throw we use now compared to then. Most every aerobatic plane now is double beveled and has over 45 degrees of throw. The ELEV halves on a Mamba I fly will hit the ground with full down deflection. I'm not familiar with the D7 you speak of but it sounds like huge throws and surfaces are not a factor.

David
Old 08-28-2020, 12:40 PM
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Originally Posted by mikes68charger
SO, I'm surprised as Im sitting here with a ton of very large birds thinking about servos for my latest bird.

I don't buy a lot of used planes, but in the last year I picked up a 1/2 sale 112in Christian Eagle with huge ZDZ210 in it, I know this plane has been flying for 4 years now I as I personally know the old owner.

I do a inspection and find he has some 300oz Hobby King servos for each tail surface and these surfaces are not small 22 wide by 14in thick. I freak out and replace with 1000 oz futaba A500 servos

I got a cool 20 year old 90in Byron AT6 built by Top Builder for Discovery Channel a long time ago with a G62. I go throw it and every servo except one was a 4.8v only futaba with max of 45oz, I replaced with futaba S3071 145oz servos 6.6v

5 years ago I picked up a CAI Razor (think BVM Bandit) with turbine and a hole bunch of 4.8v 55oz old futaba servos, I know this is all they had at the time these planes where built but these are 200mph jets and anyone building a jet today would think you crazy for putting a 55oz servo on anything except an air retract valve.

This week I picked up a 1/3 Scale Balsa USA D7 with a DA85 running HS645 servos on the elevator (130oz) and HS5645 on rudder and ali (166oz) at 6.6v.(I only use life packs not a lipo fan as I hate pulling battery's to charge. them. One of the HS645 on elevator is not working correctly ie not going back to a center well. So I replaced them with some futaba S9177SV as I had 2 new ones sitting on my shelf. but at 512oz vs the 130oz that was in there Im starting to question my self. Im sure these servos are over kill but now should I replace the HS 5645 in the wings also?

There used to be this great Blue Bird servo torq calculator online that pulled its calculator off as there was some comments about it being used to calculate drone servos or full size aircraft servos. I don't really know, but it was amazing to see how little torq is need for a huge control surface like this D7 has but with a max flying speed of 70mph there is little force needed according to the calculator.

Heck my first giant bird is a one off 160in C130 with 4 huge electric motor set up with my home made 16X12 X 4 blade props that can pull 100feet straight vertical on take off, I putt S9177SV on every control surface as at 78 pounds I had to get it LMT1 Certified and didn't want any question as if I had enough servo power even thought that old Bluebird site said I would of been safe with HS645 on all surfaces due to there small size and top speed of 85mph of this plane.

As every few months there seems to be a new 300-500oz bad ass servo with a cost of upper $140 each, do we really need such powerfull servos on a 1/3 scale D7 or is it because us jet guys just want the best of the best, Im feeling lost on what to do with this D7 which is crazy to me.

Ill be honest, I have never flown a WW1 plane. So this D7 will be my first
Whenever I buy servos, I buy digital HV high torque servos, it doesn’t really matter what I put them in, they are ready to go.

Bob
Old 08-28-2020, 05:24 PM
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For kicks and giggles.

https://www.radiocontrolinfo.com/inf...ulator/#Torque

Old 09-01-2020, 08:36 AM
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Well I left the HS5645 in the Ali and it was all good. I didn't realize it has a 28X6 prop on the DA85. So my top speed was very very slow. LOL

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