Pyro's Ju-88 bash!

pyro-manic · January 24, 2009, 10:33:44 PM

The inspiration for this was seeing a picture of a Ju-88's nose and being reminded of a Short Shetland somehow.

Anyway, I'll be bashing a 1:72 Revell Ju-88 into a flying boat. Layout will be similar to a Catalina, with a parasol wing mounted above the fuselage. There will be a gun position in an extended nose, possibly two waist positions on the rear fuselage, and an observer/gunner position on top of the wing. The empennage will be altered to a T-tail configuration, to keep the surfaces out of the water. Fuselage will be deepened by adding a hull, and the cockpit will be open-topped. Probable user will be 1920s/30s era pirates, a la the Porco Rosso animated film.

Does anyone have any suggestions on how to build a planing hull for a flying boat? I'm not sure how to start...

Taiidantomcat · January 24, 2009, 11:12:08 PM

First off great concept! I think the best way to do it would be like they do on real boats. make the "spine" (keel) and then added the "ribs" (bulkheads) throughout it. from there you just get about (.020is my best guess) strip styrene planks and "get her done." Just cover as best you can with the planks (it won't be perfect) trim to shape and fill and sand away. or find a cheap boat kit out there and glue it to the bottom, that works too.

GTX · January 25, 2009, 11:10:15 AM

Looking forward to this.

Regards,

Greg

The Rat · January 25, 2009, 11:44:00 AM

Putting a hull on a fuselage eh? Most of mine have been done thusly: Assemble the fuselage first, and then use a chunk of balsa. Get the width and length first, then start carving out a hollow to drop the fuselage into. It doesn't have to be exact, just close enough to glue on with copiuous amounts of putty. Be careful though, some types of putty can melt plastic. Once it's on good and firm you start carving the hull shape, begin with the V and progress to the nose contours. Collect all sorts of rounded thingies to wrap sandpaper around for this part, you'll figure out soon enough which diameter is best for the size you're doing. The toughest part I've found is getting the step, first you have to decide how far along you want it, then whether it's going to be a knife edge or rounded. Knife edge is easier, but aerodynamically inferior. If you're doing an early WWII era model then a knife edge should be fine. Study lots of pictures of flying boat hulls until you're happy with your overall impression of how they look, and keep referring to them as you work.

Balsa ca be a problem when trying to get a smooth finish. DO NOT use dope, if it touches the plastic it will probably ruin the whole project. What I've found to be a safe substitute is a 50/50 solution of white glue and water, just brush it on and let it soak in and dry. You can probably get away with more water in the mix, too little and the glue can get gummy when you sand it.

If you make a hash of it the balsa is easy enough to carve off down to the putty, at which point you repeat the process. Fortunately I've never stuffed anything up that badly... Yet!

Be prepared for some swearing and tears, and the odd moment of trepidation as you approach the bench each time. It's all part of the learning process!

pyro-manic · January 25, 2009, 01:45:20 PM

Wow, Rat - now that's an answer! Many thanks.

Chrisonord is very kindly sending me a spare 1:32 float he has, so I'll be looking to see if I can adapt that, but I will probably have to do some carving and sculpting.

Taiidantomcat: interesting idea! I'll have to experiment.

Thanks for your support guys - much appreciated.

The Rat · January 25, 2009, 06:45:29 PM

Here's some pics that might help explain what I was talking about. First is a 727 I turned into an ekranoplan, the centre section was grooved sheet plastic reinforced with sprue:

Next, balsa was added ahead and behind:

And then shaped:

This Transall was turned into a flying boat, you can see how much balsa I used, better too much than too little!

pyro-manic · February 10, 2009, 03:00:36 PM

Here's a bit of an update on this. I've built the new one-piece wing, and I've started on the fuselage/hull. I'm using a 1:32 float to form the basis of the boat hull, but I'll be widening it as a whole, and sculpting/carving the bow to fit.

Hull mock-up:

The hump on the top will be a heavy gun position, and the cockpit will be in front of and underneath it. The white nose part is just a placeholder - I'll be scratching a new one later. The tail will also be lengthened and raised.

Mock-up with wings positioned:

I'll have to build a big main "strut" to mount the wings on, and there will be two long ones joining the fuselage to the engine nacelles. I may also change the engines to radials (by just using the '88's radiators and props on the front of the wing) - the nacelles are rather long with those big inlines.

Thanks again for the help, Rat - it will be very helpful.

chrisonord · February 12, 2009, 04:55:41 PM

Nice work Alun,
It's good to see that float came in handy, I will be watching this one thats for sure.

pyro-manic · February 23, 2009, 11:41:06 PM

Bit of an update on this one. Progress is slow, but there's a lot of work going into it!

Building the main gunner's position. He gets his own little area, complete with radio (the big square thing) and random gubbins:

And here it is with the lid on, showing the door into the boat's interior:

Have to finish this part before I can stick the top on and putty it up. The cylindrical thing on the floor is the base for the seat.

I've extended the rudder with plasticard and milliput, to give it a larger area:

Still needs another layer of putty and sanding to smooth it out, but it's getting there. Here's the mockup of the whole tail area:

Next to do, build the sides of the fuselage and fair in the hull, then build the cockpit and pylon for the main wing.

sequoiaranger · February 23, 2009, 11:58:07 PM

>I'll have to build a big main "strut" to mount the wings on, and there will be two long ones joining the fuselage to the engine nacelles.<

Kinda like a Junkers version of a Catalina, eh? This **IS** interesting!

pyro-manic · February 24, 2009, 12:02:35 AM

Yup - that's the idea!

It won't be Junkers, though, but some spurious Mediterranean company. I'm thinking Barbary Pirates, or Knights of Malta patrolling against them...

Zeke · February 24, 2009, 12:11:31 AM

He he he...lovely stuff!...this is going to look great I can feel it in me bones!...

So what kind of colour scheme are we talking about here?...inquiring minds need to know...

The Rat · February 24, 2009, 05:36:04 AM

Quote from: pyro-manic on February 23, 2009, 11:41:06 PM

Have to finish this part before I can stick the top on and putty it up. The cylindrical thing on the floor is the base for the seat.

Looks like it needs a seat with a hole in it...

Daryl J. · February 26, 2009, 11:17:42 PM

Yours truely thought of the loo too.

Daryl J., rather admiring this build up

pyro-manic · June 17, 2009, 04:34:20 PM

Ok, looong time since I've updated this, and there's been a re-think on the hull, but there is now some progress to show:

It might not look hugely different, but there is now a wider hull (the original was way too narrow), an extended tail boom, the skeleton of a bow (this is not easy!), and a T-tail. I'm currently building the cockpit and the pylon to hold the wings, and then I'll be enclosing the hull sides and PSR-ing the snot out of it to get it all smooth before the details and wings go on.

I've also decided that the kit props are horrible, so I'll be getting some new Aeroclub ones and some exposed radials as well - I'm thinking Bristol Mercuries, though any other suggestions are welcome. I'm looking for a decent amount of power, to give this beastie enough grunt for speed and lifting capacity. Late 20s/early 30s timeframe.

EDIT: Oh, and if a mod could move this to Current Projects that would be great.