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Author Topic: Which servos for my Highside slope soarer?  (Read 421 times)

Offline Two-Six

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Which servos for my Highside slope soarer?
« on: March 12, 2018, 20:14:06 »
I need to buy some servos soon I think I want digital resin geared not ball raced ones at around the £5-£7 price range.

The size of them needs to be about like this: 

In-Wing Aileron servos:  Maximum size of the aperture in the wing is about 16mm deep ( thickness of the wing) , 78mm long (front to back) and 50mm wide, so I need two servos that are less than 16 mm wide , 78mm long and 50mm high.

The plans show the two servos for the elevator and rudder should be 40mm long and 30mm high.

I have tried to calculate the torque needed for them using  this calculator http://www.mnbigbirds.com/Servo%20Torque%20Caculator.htm

The results say I need 1.8Kgcm for the ailerons and 3 Kgcm for the rudder.

However as the tail is in two halves that are joined together, they have a fairly large V shaped notch out of them in the center.   So measuring the length and chord gives me a huge elevator surface and the calculator says I need at servo with nearly 9Kgcm of torque.  That can't be right....

The dimensions of the control surfaces are as follows:
Aileron chord: 40mm length 600mm
Rudder chord (Approx) 80mm and 230mm length
Elevator chord (Approx) 70mm length 570mm however this is the whole length and doesn't account for the V shaped notch in them which is about 130mm wide...

I don't really know how to calculate this but I have also gone with a nominal lenght of 220mm each side giving 440mm total length....

The calculator says I need a 4 Kgcm servo with these figures...Much more reasonable.

I have also guessed at about 45 MPH for its top speed, no idea if this in the right area for this glider.

Any suggestions as to which ones I should get?  I am probably going to get them from HK as I might also get another AXN floater jet/Clouds fly airframe from them and some other stuff so I can save on postage but I could also go to another supplier, I am not too bothered.




 
Nighthawk Pro, Trex 450 L Dominator 6 cell *FLOWN*, Blade 450-3D, MCPX-BL, MCPX-V2, Hubsan X4, Seagull Boomerang IC .40 trainer, HK Bixler, AXN Clouds fly,, Spektrum DX7, Taranis, AccuRC

Offline Bad Raven

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Re: Which servos for my Highside slope soarer?
« Reply #1 on: March 13, 2018, 08:58:49 »
I thought it was designed for simple standard servos?

Only pics I have seen show std Futaba F-S148's dating from the Flintstone's era!

Offline hoverfly

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Re: Which servos for my Highside slope soarer?
« Reply #2 on: March 13, 2018, 10:26:33 »
https://hobbyking.com/en_us/corona-ds-239mg-digital-slim-wing-servo-metal-gear-4-6kg-0-15sec-22g.html

I have used the above in several slopers, the form makes mounting /replacing if necessary  easy.
Reptile folder , alien 500 , F/ Shark Attitudes,
 .Tarot 650, Air-rio Kinetic.. DX9  Various wings and planks.. Taranis x9D+..Mavic..Armattan.. Chameleion...
Massive over draught.....

Offline Two-Six

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Re: Which servos for my Highside slope soarer?
« Reply #3 on: March 13, 2018, 12:25:08 »
Thanks Hover, that servo is just the ticket.  I think I need these slim wing servos. At 10 mm thick that gives me about 6-8mm head-room, any other form factor won't fit.  Have you got any suggestions for the elevator and rudder servos? 

The plan wants them to measure 40mmx30mm (width unknown), I think that's "standard" size isn't it?
Nighthawk Pro, Trex 450 L Dominator 6 cell *FLOWN*, Blade 450-3D, MCPX-BL, MCPX-V2, Hubsan X4, Seagull Boomerang IC .40 trainer, HK Bixler, AXN Clouds fly,, Spektrum DX7, Taranis, AccuRC

Offline hoverfly

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Re: Which servos for my Highside slope soarer?
« Reply #4 on: March 13, 2018, 13:07:29 »
https://hobbyking.com/en_us/corona-ds238mg-digital-metal-gear-servo-4-6kg-0-14sec-22g.html

The above might suit . nice and skinny so they can sit side by side. ::)
Reptile folder , alien 500 , F/ Shark Attitudes,
 .Tarot 650, Air-rio Kinetic.. DX9  Various wings and planks.. Taranis x9D+..Mavic..Armattan.. Chameleion...
Massive over draught.....

Offline Two-Six

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Re: Which servos for my Highside slope soarer?
« Reply #5 on: March 13, 2018, 13:47:09 »
looks good to me, thanks again.  I was looking at the analogue versions of these actually, didn't notice they were analogue or there was a digital version.  I think they should be powerful enough too  :crossfingers:
Nighthawk Pro, Trex 450 L Dominator 6 cell *FLOWN*, Blade 450-3D, MCPX-BL, MCPX-V2, Hubsan X4, Seagull Boomerang IC .40 trainer, HK Bixler, AXN Clouds fly,, Spektrum DX7, Taranis, AccuRC

Offline Two-Six

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Re: Which servos for my Highside slope soarer?
« Reply #6 on: March 13, 2018, 14:33:53 »
They are on the way!

Along with a new AXN floater jet fuselage https://hobbyking.com/en_us/floater-jet-epo-arf.html and a couple of these https://hobbyking.com/en_us/turnigy-nano-tech-1800mah-3s-65-130c-lipo-pack.html?wrh_pdp=1

I am going to make the wings and possibly the horizontal stabiliser removable when I build this AXN.   They were fixed on my "version one" (which has been beaten-up severely).

Its such a nice thing to fly I intend to take it away in the camper van  so I need to be able to store it easily and be able to put it together quickly and easily.

I might use multiplex 6 way connectors of something similar for the wing servo connections and something like magnets or rubber bands and stick on hooks to hold the wings on with.

I need to figure out the finer points of how its going to work.  There are lots of build tips tricks and mods for this kit out there to look at.
Nighthawk Pro, Trex 450 L Dominator 6 cell *FLOWN*, Blade 450-3D, MCPX-BL, MCPX-V2, Hubsan X4, Seagull Boomerang IC .40 trainer, HK Bixler, AXN Clouds fly,, Spektrum DX7, Taranis, AccuRC