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Old Nov 24, 2012, 01:09 PM
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geoffers0_0's Avatar
Bristol, UK
Joined Jun 2008
209 Posts
Axle build progress...

I thought it was time to start adding some details showing the progress of my Axle rebuild – hopefully this will inspire Chip, Geoff_S, BigSwede etc to kick start their Axle builds

I had pretty much a blank canvas to start with, and am planning the build with the following
  1. Removable AMT for ease of transport.
  2. Take out the Bowden Cables and replace with some decent snakes.
  3. Add a bigger rudder.
  4. Sliding actuators for the wings.
  5. Separate servo on each wing (so I can play with wingeron/pitcheron alternatives).
  6. PopUp canopy airbrake.

Hopefully the cockpit area will be big enough, as there will be 5 servos plus the wing actuators – seems pretty roomy but haven’t started working out the layout yet.
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Old Nov 24, 2012, 01:10 PM
I'd rather be.....
geoffers0_0's Avatar
Bristol, UK
Joined Jun 2008
209 Posts
First job was to fix the broken AMT mount.

I started by digging out the rudder post, which would also give me access to remove the Bowden Cables.

I had found some 10mm box section Aluminium for the mount in B&Q (DIY superstore), and with a bit of cutting & squeezing got it to fit nicely in the tail. This was epoxied in place using Hysol 9462 (which is my fave epoxy for critical work)
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Old Nov 24, 2012, 01:11 PM
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Bristol, UK
Joined Jun 2008
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Next was to convert the elevator to be plug and play.

Big hammer to crack a small nut, but the router made short work of cutting parallel slots for some carbon tube which I epoxied in place using quick epoxy & microballoons.

With everything fixed in place, I could be sure that the tubes would line up when I cut the ele in half . Some 3/32” rod was a perfect fit in the tube and the tail goes together a treat, and will be held together with tape.
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Old Nov 24, 2012, 01:12 PM
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Bristol, UK
Joined Jun 2008
209 Posts
To drill the hole for the tail-mount axle, I butchered some square-clampy-thingies I had (think bookends) and routed a 5mm slot for the wing joiner, which meant I could (hopefully) drill the hole for the tail-mount perfectly parallel to the wing-mount axis.
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Old Nov 24, 2012, 01:13 PM
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Bristol, UK
Joined Jun 2008
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First dry-run of the AMT mount seems pretty successful – I’d made a short plug from an old bit of carbon wing-joiner and CAed that in the top of the mount to make it nice & strong.
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Old Nov 24, 2012, 01:59 PM
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sixty9mustang's Avatar
United States, Mt, East Helena
Joined Oct 2005
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Rudder

Hello,

I grabbed some images of my rudder for you. Dimension at the top is 1.5 inches and bottom is 3.5 inches. It weighs 10 grams with 3 Robart pinned hinges.

Nice start to your rebuild, I have subscribed and will be watching enthusiastically


Thanks,
Chip
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Old Nov 24, 2012, 11:05 PM
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Brisbane, Australia
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Quote:
Originally Posted by geoffers0_0 View Post
...This was epoxied in place using Hysol 9462 (which is my fave epoxy for critical work)
Does this stuff stick well to the polyester resin used in the fuselage ? I had read somewhere that epoxy couldn't be used, and tracked down (at wicked expense) some "Stabilit Express" polymethacrylate from Germany, specifically for use on the Axle. I've used it to glue in AMT pivot and servo frames in the fuse, and it seems pretty solid. No idea whether it was really needed or not though...
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Old Nov 25, 2012, 03:19 AM
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geoffers0_0's Avatar
Bristol, UK
Joined Jun 2008
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Quote:
Originally Posted by sixty9mustang View Post
Hello,
I grabbed some images of my rudder for you....
Thanks Chip - I'm going to steal your design and since I'll be making a new rudder post can extend that a bit to make a nice hidden-hinge with the Robarts. (BTW: will your rudder pushrod work? : the exit looks too close to get much pull)
Also decided to put in a bell-crank for the AMT rather than a snake turning through 90deg.

Quote:
Originally Posted by Geoff_S View Post
Does this stuff stick well to the polyester resin used in the fuselage ? I had read somewhere that epoxy couldn't be used...
Hi Geoff - I think there's a bit of misconception about epoxy used over polyster (though I think polyester doesn't bond quite so well to epoxy). Hysol produces a super strong bond (it's the sort of stuff they bond composite car bodies to chassis etc), and is thixotropic so doesn't run or sag. Quite expensive so I use it sparingly BTW: you don't need an applicator gun if you make sure the nozzles are clean when you put the end-cap back on

West have some useful information sheets eg http://www.westsystem.com/ss/assets/...2Polyester.pdf
Quote:
Most production fiberglass boats are made with polyester resin. WEST SYSTEM epoxy is a wonderful material for repairing polyester fiberglass boats. One reason for this is the ability of epoxy to form a stronger mechanical bond to a damaged laminate than polyester resin
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Old Nov 25, 2012, 01:39 PM
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United States, Mt, East Helena
Joined Oct 2005
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Quote:
Originally Posted by geoffers0_0 View Post
Thanks Chip - I'm going to steal your design and since I'll be making a new rudder post can extend that a bit to make a nice hidden-hinge with the Robarts. (BTW: will your rudder pushrod work? : the exit looks too close to get much pull)
Also decided to put in a bell-crank for the AMT rather than a snake turning through 90deg.
No Problem Geoff, it is a pretty simple rudder design, yet very rigid and fairly light.

Good eye, yes the pushrod exit is a bit close, but the control horn will have to set back a bit (behind the fiberglass tube), which will give it some room and I can trim the exit forward a bit, so hopefully I can make more room.

If you are planning on putting a bell crank in for the AMT, how much weight difference would it be to just put the servo there instead? It might be worth checking out, since you are planning dual servos for the wingerons.
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Old Nov 25, 2012, 03:32 PM
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geoffers0_0's Avatar
Bristol, UK
Joined Jun 2008
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Quote:
Originally Posted by sixty9mustang View Post
If you are planning on putting a bell crank in for the AMT, how much weight difference would it be to just put the servo there instead?
I think it would be too much faff to put a servo there, though agreed: I may find I need extra weight in the rear to counter the additional servos up front.

BTW: What servos have you used to drive the wings? Are you sticking with one servo to drive both, as designed?

I actually managed to get some sloping in today - flying my Blade in a gap between the monsoon rains we're having at the moment

Consequently, not much done today, though I did manage to knock up my bellcrank from a spare servo arm - CA'ed some brass tube in the screw hole, using the "Sodium Bicarbonate" filler technique - rock solid & no slop. This'll be one of the last things to be fitted, but will make a "tray" mount epoxied in place in the tail
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Old Nov 25, 2012, 04:45 PM
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United States, Mt, East Helena
Joined Oct 2005
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Quote:
Originally Posted by geoffers0_0 View Post
BTW: What servos have you used to drive the wings? Are you sticking with one servo to drive both, as designed?

Consequently, not much done today, though I did manage to knock up my bellcrank from a spare servo arm - CA'ed some brass tube in the screw hole, using the "Sodium Bicarbonate" filler technique - rock solid & no slop. This'll be one of the last things to be fitted, but will make a "tray" mount epoxied in place in the tail
I did install a single servo, when I was building it back in 1989 I installed a Cirrus CS-130 (same as the Futaba S-130), it had an advertised 55.0 oz of torque on 4.8 volts. Which would be 1.56kg/cm, I guess It was one of my favorite servos back then.

The bellcrank you put together would be pretty light and should be strong enough. With 4 servos up front, it may start to get crowded a bit, maybe not, as you can use fairly small servos now.

Here is a strange thought, please be kind, as I have these often, HAHA! Would it be possible (since we are talking about using 2 servos, possibly), if you ran the servos, sideways in the fuse so that the servo head or arm faced the outside of the fuse and rotated vertically (servos would face opposite directions of each other)? Could we then use the servo arm as a direct drive to actuate the wings, eliminating any drive device altogether. In other words, the drive pin would go through the fuse directly into the servo arm.

Curious,
Chip
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Old Nov 26, 2012, 01:12 AM
I'd rather be.....
geoffers0_0's Avatar
Bristol, UK
Joined Jun 2008
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Quote:
Originally Posted by sixty9mustang View Post
Could we then use the servo arm as a direct drive to actuate the wings, eliminating any drive device altogether.
In principle, I don't see why not (unless you are adding mechanical advantage with the bellcranks) However the fus would need to be pretty wide, equating to twice the servo depth plus some.

I've just ordered some Towerpro MG996R 10kg servos for the wings (20x41x43mm) so side-by side these are 40mm, but end on would be 80mm
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Old Nov 26, 2012, 01:47 AM
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The other problem with this proposed arrangement is that the arc travelled by the servo horn won't match the arc travelled by the wing drive pin. I can do a sketch if this doesn't make sense

I've put two DES587 servos side-by-side and will drive the wing pins via short pushrods (so pretty much the same as the original design, but with two servos instead of one).
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Old Nov 26, 2012, 01:58 AM
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United States, Mt, East Helena
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Originally Posted by Geoff_S View Post
The other problem with this proposed arrangement is that the arc travelled by the servo horn won't match the arc travelled by the wing drive pin. I can do a sketch if this doesn't make sense

I've put two DES587 servos side-by-side and will drive the wing pins via short pushrods (so pretty much the same as the original design, but with two servos instead of one).
That is true, but if you slot the horns, slightly it might provide enough clearance to use them in this fashion. I guess it would also depend on how much movement you needed and how long of arm you could use. Most likely not too practical, especially in this application.

Thanks,
Chip
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Old Nov 26, 2012, 03:15 PM
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If You use the stock wing rod make sure you have more on hand as it will bend easily if the landing is not perfect. also ive run across two different versions of this kit. Maybe this thread will get me back in the garage! Waiting to see how you get your snakes secured.
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