SE5a - dogfight double

[Marc ROCHE]

Do you resolve the twisted wing?

[Dad_flyer]

Back on this build after a bit of a break.

Good news is that the wings look OK. There was a slight twist after I made them, and I tried to get that out by twisting back when shrinking the covering. I did not think it had really worked, but I checked them over after they have been sitting around for a few months and they are fine. Time to move onwards to the tail and control.

[Dad_flyer]

Decided to use ply control horns, the plastic ones just did not look right. Cut-down versions of the FliteTest laser cut horns

Fitted to slots cut in the rudder and elevator, covered with tissue and dope.

Elevators joined as well.

[Dad_flyer]

Continuing the updates of work over the last week.

This was my first try with real sanding sealer and real dope, rather than water-based alternatives. It is so much easier to use, apart from the fumes. I particularly like that you can re-activate with thinners, so mistakes seem less final.

On to the servo position and control run. Decided on 4-Max 9g servos. Metal gear for the rudder as it looks as though it will be on the ground on landing. For the rods I decided in the end to use snake outer, but piano wire inside as it is nearly straight and it seems to run smoothly enough. For adjustment I am going to try to solder 2mm threads on the end for small ball links. Z bend on the servo end. The 2mm thread will slide back through the snake to get the whole rid out if I want to.

Run designed and tubes in. Servo position found.

Extra holders added, and servo screw positions backed up with spruce spare from the struts.

Back rest triangle and the head rest fairing also attached.

[Dad_flyer]

The lipo may need to go forward into the cowl for balance. I have tested getting it in and out and the hole was not quite big enough. Also I plan to put the ESC in the front rolled deck, with a balsa plate under to keep it up away from the battery. That means the battery needed to be a little lower. So made the firewall hole bigger downwards, and also enlarged the hole for the ESC wires so that it will take all three connectors together. With the wing on it would be hard to thread them through.

[Nick Cripps]

DF,

If you haven't already glued the snakes in place, you might find easier to get a smoother run by crossing them over before they exit the rear fuselage.

[Dad_flyer]

Snakes are not glued yet. I did think about crossing them and tried it. That makes it straighter in the fuselage, but seemed to be more of a bend at the end to be straight on the rudder/elevator. They will be slightly straighter than in the photo when properly pushed in to the exit holes.

[Dad_flyer]

Made a complicated shape

To separate the ESC and battery

but it was probably a waste of time. The battery is then a really tight fit, and so is the ESC. I shall put it to one side and see if I can get fingers in to velcro the ESC to the rolled deck instead. Easy with the wings not on yet, but it needs to work after the wings are attached.

[Dad_flyer]

The comments from NC had me looking at the control rod runs again. A little more work with a round needle file and the run is almost straight. Still in a good direction to meet the horns. Now glued and an extra brace to hold where they exit the fuselage.

Also soldered threaded rod to the ends of the pianowire and put z-bends at the servo end. Now, if only I could find the bag with the spare horns and the little screw. I have one, but not both....

Next I need to join the tail surfaces on and do the bottom decking. For that I need to paint first, as the rudder is a different colour. While waiting for paint to dry I painted up the top wing gun. Also tried working out a more scale exhaust. The plan calls for 9mm half round, which is a bit big, and the full size is separated from the fuselage. This is using a bamboo skewer:

I think it will work, when I get that far.

[Dad_flyer]

Rudder painted. I got some proper Tamiya modelling masking tape. I have only used standard and cheapo masking for decorating before, and never got a good result - always some paint creeping under. This went on easily and gave a really nice edge.

The bit that looks wobbly on the red edge is glint where there is a dip in the surface, the masking worked perfectly across that. Right tool for the right job 😀.

I also found the missing bag and screw.

As all servos apparently use different screws, finding spares seems impossible.

[Dad_flyer]

Roughly connected the controls and the throws were far too big. Moved in a hole on the servo arm, but then the servo is not in line with the snake tube. So I have moved the servos apart as that was easier than moving the snakes. I shall then use shorter horns so that they don't hit the sides.

Also trimmed the snake tubes back.

 

Edited By Dad_flyer on 07/06/2019 21:06:16

Edited By Dad_flyer on 07/06/2019 21:08:01

[Dad_flyer]

It feels as though the build is getting somewhere now. Now I am happy with the control rods I added and shaped the bottom decking. I put it on cross-grain.

Then  a coat of sanding sealer, and covered the whole  fuselage with tissue and dope. I used white tissue so no point in a picture, you can't see it.

 

Edited By Dad_flyer on 08/06/2019 18:35:41

[Dad_flyer]

This has slowed up by flying (and mending...). It is one servo down as I stole that for another model. Anyway, time to stop faffing and put the wings and tail feathers on.

First a quick check of all-up weight and CG:

19oz, with battery, but still missing a servo and receiver, so 20oz probably. Well below the 24oz plan weight for brushed 400 and nicads.

CG is not far off with the battery right forward into the cowl. Not easy to check properly without the wings actually attached. I shall put in a bar to hold the battery forward and then it is time to attach the wings.

[dan h]

hi dad flyer,

i have just come across this thread and i have enjoyed what i have seen and read so far. it is looking like a nice little build im sure the finished plane will look great!

thanks

dan

[Former Member]

[This posting has been removed]

[Dad_flyer]

Thank you Dan and DM.

I am enjoying the build, but it is fiddly finding where to put things with such a small fuselage.

[Dad_flyer]

The wing has to go on, so the battery and ESC positions need to be finalised. Finally after a day of trying different things, including ESC in the cowl, I have the ESC position. Opened the hole in the front former to hold the wires, and a BBQ skewer to hold it up.

A cable tie or blob of hot melt glue on the motor wires will stop it sliding back.

This keeps the ESC out of the way of the battery.

Edited By Dad_flyer on 07/08/2019 20:41:05

[Dad_flyer]

Then the battery needs a tray to guide it to the hole in the front former and hold it forward, while also allowing me to get it in and out.

The final holder, liteply base and balsa bits.

Front lip of the ply thinned to just the top sheet, to locate in the former.

The slope helps the battery in over the lip. To get it out I can (just) reach in and lift the wires with one finger to raise the battery over the lip.

Installed:

[Dad_flyer]

I kept some thin balsa shavings from earlier. Glued a couple of these on each side to smooth the battery box sides into the hole to make sure there is no lip for the battery to catch on.

You need to zoom in to see them.

The battery in:

It is quite cramped, but not too difficult to get in and out for each flight.

Airflow is through the grille on the cowl and out of the cockpit.

[Dad_flyer]

The obligatory dry fit photo. A patchwork of colours. The grey is Halfords plastic primer over yellow Easycoat. Covers well.

Bottom wing is now attached and have been painting it up before fixing the tail, struts and top wing. The light colour I have for the underside of the wing is a Humbrol acrylic gloss. The coverage is really poor. The green is a Humbrol acrylic matt, which covers in one coat.

[Dad_flyer]

Spent a large part of today on the lower hatch over the servos. On the plan it is a piece 1/2" wide behind the wing, then a loose plate. I made it from a single piece of liteply, with a deep score nearly through from the inside. Then covered with tissue and dope to make a hinge with the top layer of ply.

Fastened at the rear with a couple of small servo screws into blocks from an offcut of the spruce struts. I might add a lug under the front to hold the hatch in the normal way in case the hinge splits.

You will see in these photographs that I did not follow one of the instructions - cover all parts before fitting _except_ the lower wing. I covered it before fitting, so I cannot now shape it into the lower decking.

[Dad_flyer]

Now the dry fit is more picturesque.

[Dad_flyer]

Next, Tony says:

How?

In the dry fit, the upper wing is too far back, by about 4mm, and too low down. I have made a jig for the leading edge relative to the fuselage, but the outer struts hold far away, so how do I make sure the wings are parallel and I am not building in twist?

[Dad_flyer]

Putting the model on a support at eye level and turning it round and round I eventually got all the measurements correct: leading edge 1mm lower than trailing edge and the upper to lower wing gap the same at both ends, front and back. Thin cyano wicked in to the strut sockets and all being well that is now done correctly.

[dan h]

hi dadflyer

have sent you a pm.

Dan