John A's Sabre build

[John A H]

Hi Phil, yes I was going to bolt a oversize fibreglass plate to the servo horn (on the HS85 perhaps use the circular horn so you can have 4 attachment screws). Test out the position required for the wire attachment and drill holes in fibreglass plate then you can shape/cut down the plate around the attachment holes (if that makes sense).

[John A H]

The lack of larger horns for the HS85 is why I ended up using a HS65 on the A4 Skyhawk. With my Sabre needing even more travel, due to the two stage/inner outer munitions drop, non of the standard servo horns were big enough. Also a custom horn means you can line up the holes for the best “straight pull” without been stuck with the standard horn geometry.

[Phil Cooke]

I've just discovered that Futaba servo horns fit Hitec splines - so I've made one from a larger Futaba output arm - sorted!

[N Pritchett]

Great work.

Don’t want to be a party pooper but: I believe you need to clear it with the CAA to have permission to drop anything from a flying object!

I know this used to be the case years ago when, in a previous existence, I ran a company manufacturing sports kites here in the UK. At the festivals some display teams needed to get this permission/license to drop small quantities of sweets from kites as they were covered by the same laws.

[Martin Gay]

Hi Neil,

We fit releasable underwing stores so that we can clean up the bottom of the wing just before landing. Otherwise the drop tanks can catch in the grass and make the model to cartwheel causing lots of damage.

Much safer that way!

Martin.

[Andy Meade]

I've never known anyone need a "license" for dropping anything from an RC model - from toffee bombers at shows, to bomb-drop competitions. The ANO states that nothing should leave the aircraft in flight unintentionally (they are dropped as required), and of course to never endanger anyone with an aircraft (risk assessment on what you are dropping covers this well).

Tally ho, bombs gone!

[John A H]

The Sabre build was on hold over Xmas and new year period due to a few other projects needing to be completed.

Over the last few weeks I've got back to work on the Sabre.

I lined the inside of the servo bays with fiberglass so that when the hatches are cut out they have some strength and retain their shape.

I am mounting the HS65 wing servos so that the control rod will be at right angles to the trailing edge. I have created 3D printed mounts for them.

On the right is the servo mount (that will be up against the top wing skin, centre is the hatch cover support frame work and left is a template to cut the hatch out of the lower wing skin.

Below shows the same but with HS65 servo inserted.

[John A H]

The servo hatch supports slot between the relevant ribs. Pins are pushed through the mount holes and bottom wing skin.

The hatch template is then slotted onto the pins protruding out of the bottom wing skin

I then cut round the outside of the hatch templates and the hatches can be removed.

and the hatch frames can be glued in.

[John A H]

The servo mounts can then be glued in position - hopefully flush with the top of the ribs.

How it looks from below with one servo in position. The string is for pulling servo wires through the wing.

and servo hatches in position

[John A H]

Before gluing on the top wing skin I needed to make sure I could find the correct position to create holes for the wing munitions release cable controls to exit. By laying a sheet of clear plastic over the unskinned top of the wing I could draw the position of the holes related to the root rib and leading edge. Once the top wing skin was attached I used the plastic sheet template to cut the initial holes

and then used small files to carefully open up the holes to the required sizes. The ball connectors are not yet glue to the control cables which made glueing the top wing skin on a lot easier.

[Phil Cooke]

Wow! Those tailored servo mounts and hatch frames are pretty cool John - excellent stuff! Presume you've seen we've had to push our event back to later in the year from our planned June date! keep well!!

[dirk tinck]

Very nice servo-mounts John!! They won't get any better !!

[John A H]

Hi Phil, saw that - now it's in September (hopefully) even I won't have an excuse if I'm still trying to finish the model the night before. The only thing that maybe a show stopper on the build is not been able to get hold of paint if everthing is closed down. I've also remembered that I haven't yet ordered the canopy so will have to contact Steve at Vortex to see if he is still working in the present situation.

Dirk, I don't think drawing up and 3D printing parts is as impressive as the artistry involved in producing your fiberglass speed brakes.

I've just started planking the fuselage so that has sorted out the social isolation requirement for the next week.

Hope everyone is well and "enjoying" the home schooling.

Edited By John A H on 24/03/2020 00:53:47