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Teakle ASW 20 3.5/1

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Martin Church
Posts: 73
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

I'm planning on putting micro rudder & elevator servos as near as I can get to the control surfaces. What would be a good mid priced servo for each control how many kg's are needed? I'm thinking over 2kg torque but less than 5kg at 4.8v

Chris Bowles
Posts: 97
Joined: 18 Mar 2015, 16:12
Location: South Devon

Re: Teakle ASW 20 3.5/1

Post by Chris Bowles »

Hi Martin, I have used MKS 135, or if you need a bit more power MKS 125, it's always better to have to much than not enough !!

Chris

Martin Church
Posts: 73
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Did you mean KST 125 KST 135 Chris?
I searched mks 125/135 but came up with nothing on HyperFlight
Guessing that around 5.2kg is fine on elevator & go fo the 125 @ 7.0kg for rudder
http://www.hyperflight.co.uk/products.a ... g-7-0kg-cm
http://www.hyperflight.co.uk/products.a ... g-5-2kg-cm

Chris Bowles
Posts: 97
Joined: 18 Mar 2015, 16:12
Location: South Devon

Re: Teakle ASW 20 3.5/1

Post by Chris Bowles »

Martin,
Yes got it wrong again, I meant KST, have been using them for a while now, got 20 plus, no problems yet, thats the kiss of death!!

Martin Church
Posts: 73
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Cheers Chris not badly priced either so I'll get one of each ordered up :)

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Peter Balcombe
Posts: 1255
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Teakle ASW 20 3.5/1

Post by Peter Balcombe »

Andrew,
I buried my elevator servo in the tailplane, with a short drive to the elevator.
Much more rigid, and simpler to rig as long as you don't let the fuselage connector drop back down the fin ;)
No problems in flight over several years use.
Attachments
Tailplane linkage
Tailplane linkage

Martin Church
Posts: 73
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Peter Balcombe wrote:Andrew,
I buried my elevator servo in the tailplane, with a short drive to the elevator.
Much more rigid, and simpler to rig as long as you don't let the fuselage connector drop back down the fin ;)
No problems in flight over several years use.
Hi Pete I've been slacking after having big issues after carving the ailerons from the living hinge as advised.
It's now impossible to tape hinge & get enough movement for the ailerons dye to warpage after being detached. Not sure what to do next really only thing I can think of is to put plastic pin hinges to control the gap to a size that will allow them to waggle the required amount.

What type of servo did you fit & what pull does it give you at 4.8v
Martin

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Peter Balcombe
Posts: 1255
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Teakle ASW 20 3.5/1

Post by Peter Balcombe »

Martin,
My aileron servos are analogue TowerPro MG90 metal geared micro units which have been fine.
They have a quoted torque of 2.2Kg/cm at 4.8v, which is how I run mine.

Andrew,
It is a long time since I built my '20' but I am pretty sure I built the tailplane as normal with the 1/4" balsa LE & elevator spar as per the plan .
I think I just dug out the enough foam to sit the JR NES xxx servo in place on the inside of the upper skin, packed it to be firmly sandwiched between the skin veneers and epoxied some small full foam depth balsa blocks around the servo lugs to make sure it didn't move around. I then glassed the completed tailplane and elevator prior to painting. I am pretty sure the servo fitted behind the diamond shaped balsa block, with the horn/Clevis on the centreline so that it sits in a slot at the rear of the fin top ply plate.

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Peter Balcombe
Posts: 1255
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Teakle ASW 20 3.5/1

Post by Peter Balcombe »

Andrew,
I don't think that there any definitive locations for the airbrake & flap servos (although the original PT kit building sketches probably show the approximate airbrake location and assume the flaps to be operated via a fuselage torque tube & single fuselage mounted standard size servo arrangement)

I mounted my airbrake servos (micro servo size) on 1/16" ply plates epoxied into balsa lined rectangular cutouts made in the underside of each wing so that the servos were completely hidden beneath the lower wing surface. There may be a length of Bowden cable tube pre-installed into wings, with end points marked on the lower wing surface, but I can't remember now. If so, then install brakes at outboard end (with sufficient space to get full brake attachment movement without fouling the tube) & mount the servo box sufficiently far inboard of inner end of tube to allow room for servo attachment and full movement. Position the servo box cutouts so that the airbrake actuation cable quick link will be in line with the servo arm for a straight push/pull action. The servo box can be fitted with a removeable flush fitting lid. Either secure the lid using small countersunk head screws (see Model Fixings website for a range of these), or use tape.

For the flaps, I bottom hinged my flaps and used Hitec HS-225MG mini sized servos located approx 1/3 of the way along the flap (as near to centre as I could get it whilst still having sufficient wing thickness to accept the servo body within a lined servo box cutout). The servo itself was securely mounted on a lower wing surface flush ply plate, which itself was firmly screwed to the servobox frame. The servo arm poked through a slot in the ply plate which permitted full servo throw movement. The 1/16" thick epoxy sheet flap horn was epoxied into the lower surface of the flap to give nearly 90 degrees down flap & zero up flap.
Note that you can mount the servo towards the rear of the wing to minimise linkage length, but remember to leave enough for mechanical adjusters to enable the servo travels/servo horn angles to be setup the same on both wings - otherwise the flap movements will be different.
Note that as the flaps are more likely to touch the ground/grass during a landing if flaps not retracted immediately before this point, significant shock loads can be transmitted back to the servo gears/servo attachments - in addition to flap drag loads - so the servos/installation needs to be able to withstand this without being torn from the wing!

I am away from home at present, but will try to remember to take some photos of my ASW20 installation when I get home in a couple of days.
Hope this helps,
Peter

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Peter Balcombe
Posts: 1255
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Teakle ASW 20 3.5/1

Post by Peter Balcombe »

Andrew,
Having just got home & looked at the original build instructions and one of the wings, I can see that my previous post was not quite right.
The original wings were supplied on the assumption that both flap & brake servos would be fuselage mounted.
Thus there was a brake Bowden cable tube pre-fitted to exit the wing root forward of the main spar.
I didn't mount the flap servo on it's cover after all. I note that the brake cable connection needs a bit of TLC :o
The attached photos should explain what I did & this works ok for me.
Attachments
Flap & Brake servo locations
Flap & Brake servo locations
Brake servo closeup
Brake servo closeup
Flap servo closeup
Flap servo closeup
Flap servo
Flap servo

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