Academy/Minicraft PV1 Ventura Restoration to RCAF Ventura AE728 (FINISHED!)

[marvinneko]

22 minutes ago, rob Lyttle said:

Marvin, I'm no expert on vacform canopy work..... maybe the only one was for the little L10 Electra which included a vacform cockpit top. I found it challenging....🤭

All very flexible and uncertain. 

I found it useful to add stretched sprue to the bulkhead at the right height to hold the clear stuff in position for a smooth roof joint. I had a couple of other bits positioned to aid the fit at the sides.

BUT... my roof was painted white with the fuselage so any visibility of my sprue addons wasn't an issue.  Your joint is all see-through, especially with the open escape hatch arrangement  

I'm just throwing it in there in case any help along those lines sparks a solution in your mind. 😎

 

The nose part looks great 

 

Thanks Rob that's a great suggestion. One option is to glue small knobs to the bulkhead which would intersect with where the painted ribs touch the bulkhead (3 of them) + the two lower corners. They could pass for being part of the rib joins. This might be hugely helpful!

Edited March 16 by marvinneko

[marvinneko]

Second round tonight after grabbing some food from the grocery store and eating some pretty terrible cookies. My goal for tonight was to end with a new canopy mould.

 

First I gathered up plastic containers from fruit and mushrooms and cut them and cleaned with IPA. I wanted 4-5 ready to go. Then I traced the window frames of the kit canopy... I did over five rounds of this to ensure lots of copies of masks. I'm hoping by having a stack of materials/copies ready to go, I won't get too bummed out if one doesn't work.

 

Then I took a file to my spare kit canopy and ground away on it until I had a gap around the edges (for the vacform plastic)

 

I have been imagining adding the bubbles in the canopy (copilot top, pilot side) using resin. I put masking tape down to guide where to put them. I built the bubbles up with small drops that I cured and layered. Not sure these are bulging enough but too much resin causes the bump to spread too much. (see failed broad one I cut off with a knife to the lower left of the tack). The vacform plastic will be bigger over it anyway. Yes these will mess up the masks for those panels 🙃

 

Here's a view of the mould with resin bumps/bubbles added.

 

Ok task list for tonight finished. Tomorrow I plan to vacform 4-5 copies and hope to get a nice one.

 

Then I'll cut them out and trim the best one to fit. I hope to have the canopy complete by end of day tomorrow. Then I can glue on everything else and weather it 😛  

 

Edited March 17 by marvinneko

[marvinneko]

if at first you don't succeed keep trying until you burn yourself 🤪

 

I thought I was clever supergluing a cocktail stick inside the canopy mould to prevent it from spreading. Maybe.

 

Otherwise, a  bit of a frustrating day.  

 

The Ventura canopy has some complex curves and the bubbles I added make it more complex. This can result in melting plastic folding near sharp changes in the canopy shape. The way around this is to lift the mould higher off the platform and extend some skirt around it to make the plastic stretch more gentle and encourage folds to be farther away from the mould.

 

Sounds easy right? Well if the mould is higher up, that means the plastic in the frame is farther from the suction platform. This means the plastic is farther from suction, won't be grabbed as tightly, and the air rushing underneath has more time to cool the plastic. If you increase time heating it, you'll bake the plastic into a white colour.

 

I tried warming the plastic more first before applying it  (good). I tried lower heat and more time to try to soften the plastic when it was applied to the mould (bad -> white). I tried higher heat overall (bad during initial phase it's too much energy and damages the plastic.) 

 

Eventually I worked out the following:

- fruit plastic is durable and works well.... others are too brittle and shrivel or turn white

- mould needs wide skirt around it to prevent plastic folds

- initially softening the plastic on a frame & away from the mould at lower heat setting is good

- once plastic is put over mould, switch to high heat to compensate for vacuum and quickly shape plastic before it whitens

- the higher mould needs the plastic to (a) be closer (so I only use half the frame with clips and not a sandwich)

- the higher mould needs pressure applied to force plastic down over the mould... this can be done by pressing on the frame while applying high heat

- use an oven mitt-- guess why

 

 

Still not perfect but much closer. Sadly I used up almost every piece of plastic and burned myself at this point. The skirt needs to be flattened out a bit around the mould... of course pushing down on it doesn't help

 

it would be a good idea to burnish along the mould while applying heat. I tried poking with a qtip but the heat melted it. Maybe this?

 

 

Should I go get more plastic? 😛

 

Hm, it has started to hail outside. Blah!

 

Edited March 17 by marvinneko

[Johnson]

It's a frustrating job David, I know from experience.

 

If at first... you'll get there!

 

Best of luck,

 

Charlie

[Wlad]

Good experimentation there, David. Glad you're keeping notes, at least here. Experiment, learn, adapt, rinse and repeat...

 

Cheers,

Wlad

[MOK61]

I'm very impressed with your home-brewed vacforming rig and your experimental technique, David.

 

Despite a career in laboratories my inclination is to become frustrated and impatient, so I change multiple variables at once and then lose track of what has worked and what has not.

 

I'm sure you'll get there and I hope the burns heal quickly!

 

Murray

[AdrianMF]

Welcome to vacforming! A few observations...

 

No concavities! I approached adding blisters to a canopy (Pink Spitfire PR 1G conversion) in a different way. I made the bubbles separately using a simple plunge mould. They were glued to the canopy by a liberal coat of Future. Not the most robust arrangement, but they haven't fallen off yet:

 

Vacforming works best for pure convex shapes. If you think about it, once the plastic has made a cone over a raised feature and touched the glasswork all around the edges, the air is trapped and it so it will never bed down. To solve that you end up having to drill tiny holes in the hollows in the mould to make sure that all the air is sucked out. That's what the "pips" on professional vac forms are - the impressions of those tiny holes.

 

Plastic choice I have never got "second time around" plastic to work, even though you'd think it should. I buy PETG on ebay. Go for the thinner stuff (20 thou/0.5mm) because it won't bubble up when you heat it. Steer clear of acetate as that goes yellow after a while - you're young enough to care! Other flexible plastics can work (eg: clear folder binders, the clear flimsy folded boxes that chocolate Easter bunny rabbits and salt and pepper shakers come in) but PETG is the gold standard. Clear polystyrene sheet doesn't work - opaque polystyrene sheet has additives that make it more pliable and it works well (but not for canopies).

 

Bubbles PETG absorbs moisture from the air and when you heat the thicker stuff the moisture turns into bubbles. So PETG, especially the thicker stuff, needs to be warmed slowly to start with. I'd rather have a wobbly thin canopy than a thick bubbly one - after all, you don't pick your models up by their canopies, do you? 

 

If it's not hot it won't mould The plastic needs to be hot. It should be sagging before you try to mould it. Playing heat over the plastic when it's stuck on the mould is the quickest way to ruin the mould.

 

Closer I use drawing pins rather than bulldog clips to pin my plastic to the supporting frame so it's as close to the vacuum bed as possible before any vacuuming happens.

 

Tendrils "Tendrils", where the plastic folds up on itself radially away from the mould rather than sticking to it, are caused by the plastic being drawn together to other bits of plastic rather than the mould because of the local geometry. Sharp edges and sharply rising forms cause that. Adding a bit of blu-tak at the back of the canopy to make a gentle ridge instead of a cliff will avoid tendrils there, but do leave a step down from the canopy to the blu-tak to give you an edge. If you are getting tendrils at the front of the canopy, put a little wall of blu-tak ahead of it (but make sure there are some vacuum holes between it and the canopy). These will stop the plastic bunching.

 

Ring:

 

Plinth (with vent holes to suck the air away at the plint/mould border):

 

In both cases, you can see the tendrils started to form but then got disrupted by the defences.

 

Lift for sharper bottom edge Raise the canopy a couple of mm above the bed with a blob of blu-tak (smaller than the canopy ) to help it get sucked down tightly at the edges.  Check that the air has an escape route all the way around so it won't form little pockets.

 

That's all folks! Er, that's all I can think of for the mo. On a reasonable day. I get maybe one in three attempts to work well, and I like to produce a spare because accidents happen when trimming. On a bad day...  well I just go and do something else instead! It's all a bit frustrating most of the time but when it works, it works!

 

Regards,

Adrian

[marvinneko]

Thanks @AdrianMF that's a great resource for my next project! I appreciate the time and examples! Some great points there. I am probably not softening the plastic enough before draping. I get it to shimmer/jiggle like jello under the heat gun but should go further. I did het a bit of bubbling in the teardrops. Yours look spectacular, by the way.

 

As I am running out of time and panicking off and on, I have to commit to a form I have if I want to take this to the show on Sunday. It's far and I have to travel 7 hrs to Toronto, then a couple days later, a few more hours to Hamilton...all by bus with the model in my lap 🙄

 

I picked thru my stack of vacforms and found another that was a better shape. Stuffed it with its mould and tack around it for cutting.

 

 

Used tape to outline cutting line a mm from the edges (blade has thickness)

 

Seated mould into cut out vacform to do filing of the edges to refine the shape

 

Masked up

 

Painted. Looks a bit loose (esp since I cut out the escape panel) but when held in place, seems like a decent fit. 

 

Will cure overnight then quickshine and glue tomorrow. Yes we have some paint damage when removing masks...  However, adding more primer in the paint sandwich (interior grey green, primer, dark earth) built up the ribs more and they look better than a thinner coat, and the primer filling gives them some interesting definition. Will try to fix the blips tomorrow.

 

I plan to superglue the left side in place. Then superglue the right side. I think the hole in the top and flexible plastic will allow this. I can't see any other way to ensure I can get decent alignment. I need the glue bond to stand up to travel. 

 

Yes, the nose fell off. Again. I had given it a few days to cure the PVA then tonight added a bit of plastic putty around the seam, which I smoothed with a damp finger (dip in water then tap on cloth... so barely damp). And it just separated again and the triangles came out again.

 

So repainted them and reglued them. I will have to resort to superglue tomorrow. I put it in the fridge to slow down the cure. Hope I can get it aligned quickly.

 

I am riding a bit of a rollercoaster with moods. Hope I can get this silly thing finished in the next couple days.

 

[AdrianMF]

Just don't try to paint the canopy framing on the bus!

 

Adrian

[marvinneko]

Well, I glued on the canopy and nose and fixed the canopy ribs. I filled gaps with resin. It was stressful and highly imperfect 😛  Some quickshine applied with a brush restored the whitish canopy edges where I superglued.

 

Applied an oil wash to the panel lines, and oil dot filter to the plane: brown on brown, and yellow on green. Managed to break off the horizontal stabilizer... yup. Hyperfocus rubbing away on it. Reglued. Need to address the seam. Also managed to get a superglue blob on my deicing boot moving the plane around-- bumped some glue on a dish. And... sanding on the tire of the landing gear, damaged the gear. 

 

Glued on the bits... landing gear, open door. Broke the door once and reglued it. 

 

Here's a dry fit of the props. They need some weathering and the starboard needs the tips bent.

 

 

I thought I was clever with the collapsed wheel, gluing it to the landing gear door and nacelle... but with the plane at an angle, the gear should be angled on the model to lie flat when set up. Not sure if I can fix.

 

To do: 

- weather props and bend tips on starboard prop

- assess landing gear and fix better

- anything I can do about glue blob on deicing boot? sanding perhaps...

- pitot tube (suitably bent)

- df loop

- finish oil dot filtering on bottom of horiz stabs and don't break them this time

 

Ah reality... it's harsh!

Edited March 20 by marvinneko

[MOK61]

That's looking good, David.

 

I had to go back to page 1 to check the scale!

 

17 hours ago, AdrianMF said:

Just don't try to paint the canopy framing on the bus!

 

Adrian

Ah..the joys of trying to do Russian grammar homework on the smoke-filled top deck of one of London Transport's finest 50 years ago!

 

Murray

Edited March 20 by MOK61

[Wlad]

It's looking good, David. Finishing a model is a balance of what can be added while not breaking something else. Sometimes I stop short of where I thought I would because too many things are breaking off. Sequencing is the key, so time spent on planning pays off.

 

Cheers,

Wlad

[marvinneko]

Everything but the aerial lines.

 

 

 

[marvinneko]

Any hints on safe transportation?

 

I have this shoe box that seems reasonable for a lap position for 7 hrs.

 

 

Something like this suspends the model in the box

 

 

Edited March 20 by marvinneko

[marvinneko]

Any tips on securing aerial lines to the vertical stabilizers? Drilling a hole into the thin leading edge seems quite challenging.

Edited March 20 by marvinneko

[AliGauld]

1 minute ago, marvinneko said:

Any tips on securing aerial lines to the vertical stabilizers? Drilling a hole into the thin leading edge seems quite challenging.

The merest dot of CA usually does the trick.

If you have accelerator then dip the end of the thread in that and then touch it to the CA it should hold..

Hope that helps,

 

Cheers,

Alstair

[Wlad]

I get my smallest drill bit and drill a hole. Then dip the end of the line in CA, push into the hole and let it sit until it dries. My models are in 1:48 so there is more room for that. Gets tricky in 1:72. Alistair's suggestion is good, though I haven't tried it.

[Karearea]

That’s looking superb! You’ve definitely landed the finish with aplomb. Love the bent props, LOVE those flaps which read beautifully against the finished article. Nice work on the transparencies too. Top notch.

[CH-53D]

That came out very nicely.  I admire your perseverance through all the trials with the canopy and other glazing.  Well done!

[SarmaT]

16 hours ago, Wlad said:

I get my smallest drill bit and drill a hole. Then dip the end of the line in CA, push into the hole and let it sit until it dries. My models are in 1:48 so there is more room for that. Gets tricky in 1:72. Alistair's suggestion is good, though I haven't tried it.

I use the same method. Actually everything depends on the drill's diameter. In the end of the day you can do a small hole with a needle as well.

[AdrianMF]

I hope you got everything to the show in one piece!

 

Here's hoping the show goes smoothly for you 🤞

 

Regards,

Adrian

[opus999]

That looks fantastic!  Good luck with the bus trip!

[marvinneko]

14 hours ago, AdrianMF said:

I hope you got everything to the show in one piece!

 

Here's hoping the show goes smoothly for you 🤞

 

Regards,

Adrian

 

Thanks Adrian! First half of the trip back to TO worked out ok-- a long 8 hours on the bus through a snow storm... today I put on the aerial lines using UV resin (then broke them when I grabbed the plane... put them on again 😛)

 

Here the Ventura is back in her box with a note reminding me not to break the aerial lines again by grabbing the fuselage.

 

 

 

9 hours ago, opus999 said:

That looks fantastic!  Good luck with the bus trip!

 

Thanks Opus! Alarm is set... route is planned... box is bubble-wrapped... lunch is packed.

 

I'd like to thank all of you who have followed along on this crazy 9-month journey. Your reactions, comments and views all helped keep things going. There were dark days at times, but I always appreciated knowing you were out there. I'm also grateful for the suggestions made and I tried to take them on board when I felt able. This was a "learning kit" for me... meant to prepare me for my 1/48 Ventura and so I tried lots of techniques and took risks and often mucked things up and redid them multiple times.

 

I'm calling this done and I've posted an RFI with some back story on my great uncle and his training, historical documents and photos, and some shots of my Ventura wearing her aerial lines. I think I will call her "Ellen" which was the name of my great uncle's mother (my great-grandmother).

 

 

[mark.au]

Your tenacity and ingenuity in this build was and is truly inspiring.  A brilliant result.

[AliGauld]

I can only reiterate what others have said.

This has been a fantastic build thread with some very impressive modelling going on and a fantastic result.

Off to the RFI.

 

 

Cheers,

Alistair