DH Vampire 1/5th Scale prototype - Kit

Re: DH Vampire 1/5th Scale prototype - Kit

Postby tigger » Wed Jun 04, 2014 8:48 pm

You're a craftsman DH and credit to you for working through such a major build. The months do tick by and seemingly faster as you get older but your months building seems pretty full to me and i bet to the others that view your work as well.
Cheers Tigger
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Thu Jun 26, 2014 5:44 pm

Hi there Tigger and all...thanks for the encouragement, but ....

There hasn’t too much obvious progress in recent weeks but work has been going on none the less. I still make up some of the Airsail R/C Kit range and I have an order from the UK for 40 Chipmunk kits and 10 each of the Auster AOP9 and the DH Beaver. An Airsail kit builder from Canterbury, Brian Price and to a degree Play Concepts were responsible for the contact ..great stuff.

However, to the Vampire. I made up some masters for Rocket Rail mountings. There were several different versions made and fitted but the set up fitted to the aircraft I am modelling featured the shortest mount brackets. These were used for ex WWII style rockets. In full size they are quite specific regards their positions with each mounting stencilled with Port Inner, Port Outer, Starboard Inner and Starboard Outer.
The rear ones have to be longer and have to be handed for Port and Starboard, but there is nothing obviously different about the front ones that demand the same treatment. For better or worse I have made patterns for a universal front mounting and a handed rear version.



Everyone who tries resin casting has their favourite method of making moulds and you will see I have used Clean Clay with plastic strips added for alignment of the halves. The sides and base are of styrene sheet. The sides are glued with CA. I use a transparent silicon and I de-air it with a vacuum set up I have. I will be casting the second side today.

I have adjusted the top line of the fuselage forward of the engine hatch and have started detail work on the area behind the pilot. In that space there is a platform on which is mounted the hydraulic reservoir. I made this using really old fashioned techniques. That is, from soft light balsa sealed with sanding sealer then covered with note paper drenched in clear dope. Finishing is easy with a couple of coats of sanding sealer then some primer. The end product weighs almost nothing.
More soon.
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Sat Jul 12, 2014 11:04 am

I’ve been obsessed with getting the rocket rail set up completed and fitted. In my setting up I found that as opposed to my original statement that there was some commonality among the pylons, in fact I found that the inboard and outboard sets are different at both front and rear positions. Foot in mouth over that I’m afraid.
RR 5.jpg

RR 7.jpg

The pylons are secured with a number of bolts and screws. The castings have a 3mm hole down through the middle. After casting they were recessed at the bottom end to accept the modified head of a standard bolt – I will replace those with a cap screw in due course. Small screws are used on the scale mounting flanges to stabilize each pylon.
RR 8.jpg

I next set about making the aft end fittings for the rail and then the actual rails. The fitting at the bottom of the rear pylons was cast from resin. They are recessed to fit over the aerofoiled pylon and also have a ali tube insert to accept the end of the rail.
RR 9.jpg



The rails are made from a piece of Plastrut ¼ round, a length of 1/8th carbon rod, a length of G10 and capped with a lightweight vac form. At the rear these locate into the rear pylon fitting and being secured by the 1.2mm bolts detailed above. At the front there is a small ali spacer and again it is secured to the front pylon with a single 1.2mm bolt.


The spacer is not fitted when the pic was taken.

This hasn’t taken very long to write but oh the pain in getting it all done! Now all that remains is to finish and paint them.
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby Dale » Sun Jul 13, 2014 7:28 am

The excellent work continues! Keep it up.
Can you expand more on the casting process and products? I've never tried it. I need to make some exhausts, this could be a good option me thinks.
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Wed Jul 16, 2014 4:41 pm

Hi Dale
Sorry about the delay. The Silicon mould material I use is B J Barnes 4644 (two part A/B). It was available from an outfit called Top Mark but alas they have closed. Barnes is in Aus and you Google them you will find a number of options available with some small packs. Keep away from Dow Corning, it costs the earth and then some. The biggest thing to avoid with Silicon (an Urethane) is bubbles and in fact this is best achieved with a vacuum set up. It is however not entirely necessary if you're careful while mixing and pouring.

There are two basic methods of making a split mould. You can pour half at a time as you see in the pictures on this thread, or you can completely encapsulate the item and then literally cut it in half. The latter approach, I believe, is used a lot by jewellers when making moulds for lost wax process. If you make a two part mould you must treat the first side with Vasoline before poring the second. 4644 Silicon mix ratio is normally 10:1 i.e Part A:Part B.

The Urethane is Era Cast from ERA Polymers, with their manufacturing facility in Australia however they have a distribution set up in South Auckland. Era cast has been used a lot by the film industry and was used to cast the cannons for the full size Mosquito Project. I was put onto an additive that speeds the process up, but that's only if you are REALLY impatient! I have also used Easy Cast and this is also available from B J Barnes out of AUS. They are able to be shipped without any special handling required. (Same for Silicon). The beauty of both these Urethane products is that the mix ratio is 1:1 by volume - nice and easy.

With Urethane, be aware that Part A is an Isocyanate and must be handled carefully. Also, it degrades quite quickly if not protected from moisture and will foam and pin hole as a result. I use a Dry Air squirt into the 1 Litre container after use and I keep the container in the Hot Water Cupboard. I'm not sure how small ERA will pack down to but Easy Cast used to be packed to 200 gram units by Top Mark. You would have to check with Barnes on this. Art Supply shops may be a source of material but you would have to watch the "freshness" of Urethanes.

There's a variety of other brand options out there and once again Google will enlighten you considerably, more so than I can. You will also find tutorials as well. I'm happy to help further with details and questions.

Hope this has been of come help. BB
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Mon Jul 28, 2014 3:00 pm

Greetings all!
Being bogged down with making Chipmunk, Auster and Beaver kits has kept me from my finishing schedule, however I’ve managed some surface detail and also dealt to the Downward ID lights under the rear of the fuselage. Initially it was thought that they were fitted but not used here in NZ, in deed painted over, but pilots of the day responded positively as to their use. It would have been much easier to have moulded the lenses and simply painted them, but as you see there was just a bit more to the task. I should have made them working and may do so in the future, but not just now.

Downward.ID.2.jpg (46.84 KiB) Viewed 3982 times

I made a simple pattern to mould the reflectors from ABS and lined these with some metal tape which I polished up a little. The bulbs are short lengths of styrene rod and the lamp lens colours achieved by spraying clear plastic with Tamiya clear colours. The outer clear covers are pressure moulded with cooling holes drilled as per the original and the rim plates are from G10. Dear old “What-would-we-do-without-him” Mick Reeves smallest screws will be used to secure the latter items.

As you see, not all the screws are in place as it will be a lot easier to paint the rear fuse area without the lenses fitted and it’s a pain to take the screws all out!
Downward.ID.6.jpg (55.14 KiB) Viewed 3982 times

As so all the evil hurried and rushed bits are nicely hidden.
This aeroplane has much more detail on the lower surfaces than on the top. C'est la vie I guess.
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Wed Aug 13, 2014 3:02 pm

Not doing too much due to work (shock, horror) but I have made two half shells for my saddle tank. I'm waiting for some Intairco fittings to arrive so I can complete the job. So, I will have just on 2.9 Litres including the 200ml Header.

Ive recently been given a UMS Hydraulic Retract conversion set and have impatiently plumbed it up on a test bench. When I've it set up properly (read "looking neat and tidy") I'll post a clip. My initial opinion is that is works very well.

I've run it on both 7.4 Volts and 6 Volts. I think I prefer the latter as everything is likely to last longer. Also, there doesnt seem to be a big difference in the speed. Either way it leaves you in no doubt that it means business, much more so than air or electric drives. The key is to have all connections secure and I have some ideas on that subject that I'll share when you see what I have up and working.

Maybe others have some experience with the system?

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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Thu Sep 04, 2014 10:10 am

At last some progress on the saddle tank. This is not the neatest job you will ever see but it does the trick and tests as leak proof. For reasons of expediency, I decided to make it over a blue foam male mould. I will make any future ones in a female mould. In spite of being fairly liberal with the resin there were still a number of pin holes to fill.

The Intairco fuel feed fitting and clunk are really excellent quality. The two vents I made myself and yes, they terminate at the top outer corners. They will be linked with a Festo Y Connector.

The tank will have a mini bulkhead at the rear end, otherwise it is retained buy the forward bulkhead and the turbine mounting rails. It’s pretty much on the CG and will feed to two regular 20oz tanks and a header all of which are just ahead of the CG.

Saddle.Tank.3.jpg (72.24 KiB) Viewed 3753 times

The Turbine case is from a soon to be rebuilt Behotec J-66. I’ve also make good progress with the Hydraulic U/C set up, but more about that soon.
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Thu Sep 18, 2014 1:35 pm

More work done on the tank set up. With all the hardware for the R/C Gear and the Turbine going towards the front it’s starting to become something of a serious scramble for space. I figured it best to get the tank situation sorted so set about making what ended up looking like a wooden puzzle for the two front main tanks. My objective is to have all the equipment mounted as modules that are easy to access and remove.

As part of this overall set-up, I made mountings for both the Turbine pump and the Hydraulic pump, both of which are to be located under each tank. These pumps will be cable-tied in place onto the dowels.

The tanks will also be secured to their mounting plates with cable ties. These are standard Dubro 24oz tanks with appropriate fittings and stoppers. At the front end the mounting plates are located with a tongue into slots in sub formers. The formers are braced forward to the main cockpit rear former.


At the back, the tank plates locate onto two ¼ inch Nylon bolts, cut down and sides flattened and drilled to accept a long “Hair Pin” clip. These bolts are threaded into a 6mm ply base. So far so good.
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Re: DH Vampire 1/5th Scale prototype - Kit

Postby DH100 » Sun Sep 28, 2014 11:42 am

Still on with the tedious stuff of tank set up s and undercarriage systems. On the latter I have finally cracked it to my satisfaction. The UMSTech Hydraulic conversion is all set up on the test bed now. In my effort to have systems in modules, I spent some time playing around with a layout and came with what you see here. Basically all the Hydraulics are on this board. The board is tucked in above and ahead of the turbine and out of the way of the intakes. There will be a photograph of that later. Just to have it all working was a reason for a glass of Red.
Top side of the board here
Hydraulics Board Top.jpg

Lower side here
Hydraulics Board Under side.jpg

Dave Gladwin wrote an article on hydraulics in RCJI some time ago and one of his comments was that when setting up you need a good supply of paper towels and he is not wrong. However, once you know what you are doing (well partly) it all becomes easier. Basically, you need to be sure of the cylinders and you need to be sure of the integrity of the couplings. I’ve used Festo for all but the nipples on the cylinders. Their Push-ins and their Barbs are excellent, however any and all Barb fittings must be lock wired.
So now I have to attach the cylinders to the retract chassis. At the moment the cylinders are anchoured to the board and you can see the strain come on at the end of each cycle.
All this is significant progress. Its been something of a stumbling block for me.
See it all working at www.youtube.com/watch?v=yG9TcipySF8
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