Glen's Models 35% Extra 330 electrification

[Adrian Smith 1]

Now comes the all important fitting to the fuselage. I did a dry fit first, but I thought for one horrible minute the box wasn't going to come out again . I took that as a good thing that it was a tight fit, however. Applied 30 minute epoxy to all joints and slots (and a few other places!) and got to work with a block of wood and a panel beater's rubber hammer.

Finished off with some triangular stock epoxied all round.

Ran out of time, home to think what to do next.

[Adrian Smith 1]

I temporarily taped the cowl on the air frame and measured to the prop driver exit.

It was around 13.7 cms. Next I had to work out the dimensions of the motor given no manual. I drew a line at right angles on the bench and lay the motor along that line and put the set square in line with the prop driver.

The measurement from legs to driver is 11.5 cms. therefore 13.7 cms less 11.5 cms suggests total stand off of 2.2 cms is required or say 22mm. The motor comes with a small stand off around 10mm and fortunately I had some Secraft standoffs 12mm in stock which makes up the difference.

[Adrian Smith 1]

 

I had to notch the motor box where the standoffs fit as the fouled the rim of the motor box.

Next I loose fitted the motor and did the nuts up finger tight.

Seems ok when comparing where the prop driver is aligned to the cowl.

 

Edited By Adrian Smith 1 on 26/09/2019 16:28:59

[Adrian Smith 1]

Next job is the one I hate and that is the drill the cowl and test fit to the fuselage with the bolts that are supplied in this case.

I used tape aligned to each claw nut and measured an arbitrary 5 cms back so when I tape the cowl back on all I need is to measure 5 cms from the back mark to where I drill the the hole. Sounds simple doesn't it? I decided I'd better not rush this part and am saving it for another day.

[Gary Manuel]

Looking good Adrian. I'm sure the engine box will be strong enough - after all it's designed for a shaky old petrol engine rather than a nicely balanced electric motor.

Any thoughts on cooling at this stage? Do you block the two oval shaped "cylinder head" cooling holes in the cowl and direct air towards the motor / ESC, or do you leave it open?

P.S. Bit of info about your motor here that might have saved you a bit of work earlier.

[Rich too]

I was wondering about cooling as well...

[john stones 1 - Moderator]

Looks cool to me.

Wants those finger marks sanding away though.

[Adrian Smith 1]

Gary, there is a sizeable panel at the base of the cowl to be cut out to allow airflow, I will also cut a air vent along the bottom of the fuselage as is normal practise with electrics. I will leave the front open as it stands. Electric motors and ESCs , at least the ones I have, which are equivalent to 60cc don't give off the sort of heat that I/C engines do. The other thing I take account of is not to advance the motor timing to any great extent which ,while it will increase power/performance would generate unnecessary heat and eventually lead to component failure. Nevertheless some cooling airflow is required as you say.

Yes I agree John, I was thinking of painting the motor box, as I don't have fuel ingress to worry about.

[Adrian Smith 1]

Thanks for spec note on the motor, Gary. Very useful. Nowhere have I found where to set the timing level. I think it is a case of suck and see. The HobbyWing OPTO ESC is set at a default 15 degrees (range 0-30degrees) , but I will reset it to 5 degrees to start off with.

[Adrian Smith 1]

Some good and some annoying news.

The drilling of the cowl for the screws into the fuselage housings went a lot better than expected. Unusually for me my measurements were spot on and all seven screws fitted first time after drilling.

[Adrian Smith 1]

Then came the numb skull moment. One of the U/C legs slipped off the side of the work bench and although I managed to save the fuselage from falling off I managed crack the underside of the cowl in the process .

Oh well I taped it up ready for repair.

Fortunately I have some fibreglass car repair material and some smooth bodywork filler which I always use to repair damaged spats.

I have now set it aside to dry. Fortunately, I have some enamel paint in the right two colours of white and dark blue from previous work on models. I will fill the external crack with filler and then get some paint on it. A bit annoying as it's a bit of work I didn't really need.

Edited By Adrian Smith 1 on 27/09/2019 20:42:06

[Rich too]

Well done and don’t worry about it, I’m super clumsy and almost every job I do something happens remember the rudder on my Sbach?

i look at it like a christening or sacrificial something or other, so the rest of the build and flying will be blessed

[Adrian Smith 1]

Thanks for your encouragement, Rich. That is the right way to look at it and I will remember it. I had forgotten the "Sbach incident" until you mentioned it. Enjoying your build by the way.

[john stones 1 - Moderator]

Yep, that bit obviously needed strengthening, good job you spotted it.

[Adrian Smith 1]

I like it, John

[Adrian Smith 1]

So today I took off the tape from the cowl and now the extent of the split is revealed. However, the fibre glass repair is very strong.

Next I applied the filler. I used a dark paste for the blue area and a lighter one for the white area repair. I then set it aside to dry hard before rubbing down.

[Adrian Smith 1]

I thought I would assemble the elevator servos and connectors using Secraft 90 mm push rods. I am using Macgregor HV MG 7232 Servos rated at 31.5kg at 7.2volt. I have found them very good servos for large scale aircraft, but then they should be for the price!. I also bought a couple of 2" servo arms from Steve Webb Models. The couplers are M3 threaded with bolts and nuts supplied.

The thing to remember with Secraft turnbuckle push rods is the end with the thin kine engraving line is right hand thread while the other end is left hand thread.

[Adrian Smith 1]

The servo slots i the tail plane needed notching for the servo wire so I use a flat file for this.

The servo then slots in easily. I drilled holes for the servo screws and reinforced the hole with thin cyno before refitting.

In goes the servo arm.

[Adrian Smith 1]

Once done I loose fitted the push rod ready to go to work on fitting the elevator horns for another dsay.

[Adrian Smith 1]

Not got much done today as short of time. However, looking at the elevator horns and comparing the small size hole drilled in them it is they are not designed to use M3 bolts that come with the couplers from Secraft. I decided to use my drill press to make a larger hole further away from end of the horn so as not to weaken the horn.

Fitting the horns is a bit unusual in methodology compared to what I have experience before according to the manual. A larger hole is cut into the film and balsa and then the notch in the horn slides on the ply beam underneath the wing skin. the horn plate being slid on to the horns prior to fitting. Not sure I like the gaping hole though, ho... hum...

[Adrian Smith 1]

Well I followed the reference notes Glen sent with the kit, but instead of using 30 minute epoxy I used Gorilla glue which my chosen weapon of choice for all horns. I used a coupler bolt to make sure all thing lined up correctly.

Looks okay I guess.

[Adrian Smith 1]

I rubbed down the cowl repairs ready for painting, but I thought I should probably cut out the air flow holes before I do the spray job.

I'll try and get that done in a day or two.

[Adrian Smith 1]

It's probably a good idea that I decided to cut the air vent before painting because once I set to work it was clear the paint adhesion on the cowl is not that great when cutting. On other aircraft cowls I have cut there has been hardly any flaking.

I used tin snips to cut first which is what i do usually then drilled holes around the curve to allow for easier cutting.

Finish off with sandpaper to smooth.

[Adrian Smith 1]

I decided on reflect to spray the whole of the blue area with auto enamel paint and not just the repair. So taping up and ready.

Off we go.

Really pleased with the finished job after 4 coats of paint. Almost no seepage through tape.

I set that aside to harden for a few days before doing the smaller white area. I took the opportunity to make some cowl bolt reinforcing plates with 32nd ply as I am not to sure of the cowl's integral strength. These will be fitted after painting is finished.

[Adrian Smith 1]

Made a start on the rudder by cutting the slot for the horn in the sheeting. The front of the horn sticks to the internal vertical liteply plate within the rudder. Once again I have my doubts about recommended this method, but we shall see. I had to measure the position accurately after estimating where on the rudder the cut is made as there is no guide for this.

Dry fitted it all and checked alignment.

I am going to use Gorilla Glue for this job purely because of it gap filling qualities rather than the recommended 30 minute epoxy. That's for another time as there is an ugly rumour that Thursday's weather is good for flying rather than workshop. 

Edited By Adrian Smith 1 on 01/10/2019 13:15:35

Edited By Adrian Smith 1 on 01/10/2019 13:16:18