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Deagostini Spitfire build and 'leccy conversion.

A fool and his money... Good job it was free!

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David Wilson 2511/09/2018 20:10:29
34 forum posts
65 photos

Well, I think it's about time I got this party started! I can't be leaving a free plane on the shelf!

empty bench.jpg

Having decided that "to make things easy", I'll go the route of a Turnigy G46 motor to replace the recommended .40 or .46 IC motor. Obviously, it's easier to modify as I build, so the first consideration is a hatch to get at the battery as I really am lazy and don't want to have to remove the wing each time. I want to have 2 batteries; one to fly while one is on the charge, so not going to go the route of "charge in place". Thing is, the space between formers isn't sufficient to ease a battery in. I think that the only option is to cut the top off one former (the one on the right between the jig brackets) to make a "U" former and strengthen the hatch opening with 3mm ply.

hatch mid former cut.jpg

To that end, I've cut the ply reinforcement first and made two "brackets" to form the front and rear of the hatch out of two layers of 1.6mm balsa laminated together at 90°. They won't be loadbearing, so I think they should be strong enough.

hatch formers 2.jpg

hatch surround.jpgI haven't cut any formers yet, just in case anyone advises against the plan! I'll bow to superior knowledge and craftsmanship.

I've filled in the predrilled holes in the firewall as I intend to use a Great Planes adjustable motor mount to hold the G46 and the fitment is different...

Dwain Dibley.11/09/2018 20:18:27
avatar
1270 forum posts
1265 photos

I built this model and also converted it to electric, it flies very well indeed. I will try and put some pics up for you of the build if it will help.

D.D.

David Wilson 2512/09/2018 10:49:09
34 forum posts
65 photos
Dwain, pictures would be gladly received!
David Wilson 2503/10/2018 22:40:47
34 forum posts
65 photos

Finally getting back to this after several mental weeks. If nothing else, I can't fault the instructions! Perfectly clear and well illustrated; youry have to be an idiot not to be able to follow them.

img_20181003_210312.jpg

What I've realised tonight is that where I'd intended to place the hatch, in front of the cockpit, actually is partially under the cockpit... embarrassed I'll have to rectify that.

None-the-less, I've pushed on and glued a few more bits together.

Front glued.jpg

img_20181002_215245__01.jpg

img_20181003_204837.jpg

I think, to try and keep the weight down, I'll have to cut a hole in the firewall to move the battery as far forward as possible. Hand cutting that square will be a test of my abilities.

Edited By David Wilson 25 on 03/10/2018 22:41:10

David Wilson 2504/10/2018 18:24:56
34 forum posts
65 photos

If there's anything I've learned, it's never work off the originals if they're likely to get damaged... So, photocopies done without scaling, and I can get on with something else while glue is seeing elsewhere.

In the interest of saving weight and mindful of an electric motor weighing less up front, saving weight behind the CoG is prudent. The question is, where? From the templates, there seem to be chunks of balsa used where a hole could save a little bit, without sacrificing strength...

img_20181004_180730.jpg

img_20181004_180735.jpg

David Wilson 2504/10/2018 18:42:43
34 forum posts
65 photos

My assessment is that some weight could be easily saved from

Template 20-3 parts D

Template 21-3 parts B

At a push, perhaps a few small holes along Parts D in Templates 21-3 and 22-3?

Denis Watkins04/10/2018 18:55:25
4057 forum posts
75 photos

Save weight yes David, but not there

The saving would barely be noticeable, but the integrity of the parts would be weakened

The tailplane experiences huge forces

Save weight on internal bulkheads

And using glue carefully

David Wilson 2504/10/2018 21:37:55
34 forum posts
65 photos

Coming from somewhere renowned for not being too flush with cash, I think I can be sparing with glue... (So I don't have to buy more!)

Being absolutely ruthless in seeking weight trimming, I weighed the wheels... 88g (3.1oz). Unfortunately, that send to be the weight of similar 3.25" Robart wheels. Only possible alternative is foam wheels which could just look, well, naff?

cymaz04/10/2018 22:46:27
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8907 forum posts
1179 photos

If you can , build some washout into the wings

Dwain Dibley.05/10/2018 17:12:10
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1270 forum posts
1265 photos

Cymaz, the wings are built with a jig, which you have to build first, and I think washout is included in the build, I had no probs in flight with my one.

A little reflex (up) on the ailerons would be easier to do maybe.

D.D.

David Wilson 2505/10/2018 22:05:25
34 forum posts
65 photos

At the moment, washout is the least of my concerns... You know the adage, "measure twice, cut once" and everything similar, like reading instructions? Here's what I've managed to do...

Reality.jpg

Here's what the instructions say...

Instructions 2.jpg

See the difference?

I've used the LHS as the RHS and vice versa. Which means that the thrust angle is in the wrong direction. I remember looking at it after gluing and thinking about the reasons for thrust angle, getting confused as to why it was left angled.

Question is... What do I do? Immediate thought was to fit a CCW prop, but that means mounting the motor offset to the left, and then the cowl is shaped wrong.

The other consideration is: can I gently cut the joints and reglue? That'll be great fun! Especially since I've all this done...

Fuselage 2.jpg

David Wilson 2505/10/2018 22:18:50
34 forum posts
65 photos
I just realised... I'm overthinking it.

I want to make it electric.
I need to build a motor mount box which will also carry the battery through the firewall.
So just build a more offset box to restore the correct thrust angle.
eflightray06/10/2018 13:51:47
avatar
599 forum posts
128 photos

If you need to mount the motor ahead of the firewall, how about using long screws or threaded rod. It also allows you to adjust the thrust angles slightly.

mount.jpg

Ray. (72" span Spitfire).

Engine Doctor06/10/2018 15:41:19
avatar
2383 forum posts
29 photos

Don't forget when you get to to building the wings to dump the long twisty torque rods for ailerons and fit a servo to each aileron . It improves the models response enormously.

David Wilson 2507/10/2018 16:53:15
34 forum posts
65 photos
I thought about threaded bolts, which may yet be used, but need to get weight forward to replace the original IC .40 motor; hence the battery box through the firewall.

I'll also be putting a servo per aileron; it makes perfect sense given the size and price of them when compared to 10 years ago.
David Wilson 2518/10/2018 19:29:00
34 forum posts
65 photos

Got a bit more done over the last week and a bit, but didn't have an opportunity to update the thread.

I pushed on with finishing off the rear of the fuselage and put off rectifying the firewall error for a bit.

img_20181012_201645.jpg

I also pushed in the fin for a quick "dry fit" to keep the interest fueled!

img_20181012_201732.jpg

In the interim, I built up the forward hatch. I'm a bit fussy on maintaining a snug fit of the parts I'm making so there's no opportunity for flex. Generally good; not so much for a hatch that's supposed to be removable!

img_20181014_154352.jpg

I had to cut out the joints with a razor saw, sand the glue off and reposition about 2mm back to give clearance for removal. I put balsa stringers below the ply surround to add strength I've probably removed by creating a hatch. I hope it's sufficient!

I also started to cut the ply to create a motor mounting box. I'm assuming that as the original firewall is just glued in with regular glue and a little of square balsa reinforcement at the edges, similar would be suitable to join the box onto the original? Had a quick read up on creating a mount box; some recommend epoxy and glasscloth reinforcement?

I admit to being unsure; with a typical weight for these of around 7lbs, the box will need to hold a motor producing 700-850W, minimum.

img_20181017_210114.jpg

Denis Watkins18/10/2018 20:04:24
4057 forum posts
75 photos

Yes David, at least epoxy. If the box is well designed, then epoxy and the strength of the timber will surfice

Sometimes, when we make an area "impregnable" then during a mishap, the energy shudders down the model causing more damage.

Building and glueing well is good enough

The model is looking very smart BTW

Edited By Denis Watkins on 18/10/2018 20:10:49

David Wilson 2518/10/2018 21:35:35
34 forum posts
65 photos
The parts I've cut for the box are actually 3mm liteply... I'm guessing "not strong enough".

Not sure what to use instead as I only have 4mm regular household ply offcuts. Too heavy and coarse is my assessment of that.
Dwain Dibley.19/10/2018 00:31:18
avatar
1270 forum posts
1265 photos

It's coming on well David,

Here are some pics of my build, How I did my hatch and my motor mount ,hopefully they will help you. I did not build a battery box, I just put a tray in the fuz. Might be a bit late, as you appear to have made a fine job of the hatch already. thumbs up

spitfire build 017.jpg

spitfire build 018.jpg

spitfire build 104.jpg

electric spitfire 006.jpg

belt and braces 002.jpg

belt and braces 001.jpg

I laminated balsa till I got the right length, it could be advanced in 1/32 increments if need be.

motor mount 003.jpg

David Wilson 2519/10/2018 06:50:12
34 forum posts
65 photos
Compared to your photos Dwayne, I appear to have over engineered everything! 😁

Still, it means that it should all work out ok.

I'll have to commit to a motor to ensure I don't build the box too long. Spacers can be added, length can't be taken away too easy.

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