DeHavilland DH90 Dragonfly

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David Whiteley
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Re: DeHavilland DH90 Dragonfly

Postby David Whiteley » October 2nd, 2015, 8:56 pm

Just for the record there is a company near us who also sells leather. They have a warehouse where you can browse around the offcuts and buy what you find. If you only want a bit of leather, or want to see what you are getting before you part with pennies it is very useful.

It is
http://www.jwoodleathers.co.uk

and is situated between Steeton and Silsden near Keighley.

Hairy Dave
Dave (Hairy)

Steve Rickett 2333
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Re: DeHavilland DH90 Dragonfly

Postby Steve Rickett 2333 » November 19th, 2015, 2:57 pm

I've been tinkering away with the exhaust system recently and have finally finished it.

The basic canisters are from Toni Clark (via Fighteraces) and come in kit form. You get the steel main body, the two steel domed end caps and an internal baffle plate. All I had to do was add some steel pipe (also Toni Clark), make some mounting brackets and silver solder it all together. I'm sorry, but I didn't take any photos building the build of these...

Here they are after a good clean down with brazing salts (to remove the excess flux and grease) and then a rough sand with my trusty powerfile.

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I sprayed a coat of Aluminium Heat proof paint and baked them in the oven (150 degrees C for 1 hour) to activate the paint.

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(I've started to install the throttle linkages, and still need to make some supports for that long pushrod, more on that later)

The flexi-tube isn't held in place, but the geometry of the set means that it's impossible for it to move or slide off.

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John Greenfield
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Re: DeHavilland DH90 Dragonfly

Postby John Greenfield » November 20th, 2015, 10:45 am

Hi Steve
What are "Brazing salts" that you used to clean up the silver soldering. I always struggle and spend ages cleaning up silver solder jobs so am interested in anything that simplifies the process.

Regards

John

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Rob Buckley
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Re: DeHavilland DH90 Dragonfly

Postby Rob Buckley » November 20th, 2015, 11:34 am

A 10% solution of caustic soda I've found works well at cleaning brazed / silver soldered stainless.
LMA Secretary - I've got a reasonable idea where you live!

Alan Cantwell 1131
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Re: DeHavilland DH90 Dragonfly

Postby Alan Cantwell 1131 » November 20th, 2015, 12:42 pm

John, we use at work, a sulpheric acid mix, but i would not suggest an industrial application for the hobbyist, but here, lifted off another forum, is a pickling solution, that should work,


For a perfectly safe pickling solution, go to either a chemist or a home brew shop and purchase some citric acid. It comes as crystal and is perfectly safe to handle.

Get yourself a small plastic container with a lid, big enough to put the parts in and fully immerse them.

2/3rds fill the container with warm to hot water, and spoon in the granules whilst continually stirring, don't put too much in at a time. Keep slowly adding the crystals until no more will dissolve in the solution. Thats it, you have a saturated citric acid pickling mix.

A small box from the chemists will cost around £1 or a bagfull from the home brew shop maybe a couple of squid. The small box will make about 4 pints of pickle. Some supermarkets stock it in their cooking departments. The chemist might ask you what you are going to use it for, as it is sometimes used for processing certain illegal drugs, so just tell them the truth.

Put your bits in and wait for an hour, and you should find that things have really cleaned up. If not fully cleaned, just put the bits in a little longer, they can stay in there almost indefinitely withou coming to harm.

Don't throw the mix away, it can be used over and over, until it starts to lose it's cleaning power.

You can add a teaspoon of domestic bleach, that will keep the fungus growth down over long periods of storage.

I use mine until it is almost black, and as long as what is growing in there hasn't got tentacles, I class it as safe to use.

You can use stronger pickling salts or even diluted nasty acid mixes, but this one is cheap and SAFE.


Bogs

Phil Clark
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Re: DeHavilland DH90 Dragonfly

Postby Phil Clark » November 20th, 2015, 11:26 pm

I was going to ask exactly the same as John.......so thanks for the explanation Alan.

Phil

sean smith
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Re: DeHavilland DH90 Dragonfly

Postby sean smith » November 20th, 2015, 11:33 pm

These guys do all you need: http://www.cupalloys.co.uk/home

Alan Cantwell 1131
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Re: DeHavilland DH90 Dragonfly

Postby Alan Cantwell 1131 » November 21st, 2015, 9:47 am

Wasnt my explanation Phil, but our way is frought with danger for the home hobbyist, unless you are suited and booted for the application, i just lifted it off another forum, cos the guy knows what he is on about

Steve Rickett 2333
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Re: DeHavilland DH90 Dragonfly

Postby Steve Rickett 2333 » November 21st, 2015, 11:55 am

Sorry for the delay guys.

You are all right, but Sean has it spot on...

Cup alloys cleaning salts are exactly what I use.

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I make a small 'bath' from a Tupperware tub and leave the whole assembly submerged for about 2-3 hours. All the flux is removed and it leaves the new joins all shining and bright. The only thing it won't do is remove the heat discolouration, but a quick sand with 200-300 grit sandpaper quickly removes that ready for painting.

Steve Rickett 2333
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Re: DeHavilland DH90 Dragonfly

Postby Steve Rickett 2333 » January 27th, 2016, 4:34 pm

It's been a pretty busy past few months...although I still managed the odd bit of time in the workshop...it's the time putting these post together that has really suffered!

Anyway...the Dragonfly has progressed well the past few weeks.

The Fuselage is completely skinned in 1/64" ply, glass clothed (50g cloth) and also filler primed in Klass Kote. Most of this will get rubbed back off before a spray coat of white primer tomorrow (hopefully)

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Steve Rickett 2333
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Re: DeHavilland DH90 Dragonfly

Postby Steve Rickett 2333 » January 27th, 2016, 4:37 pm

The Fullsize had a very characteristic 'overlap' of plywood running down the sides of the fuselage. This just wasn't practical to do with 1/64th ply, so I have replicated it just as I would with metal overlapping panels....

3 layers of electrical tape, then build up a layer of car body filler.

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Lots of dust later....

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Steve Rickett 2333
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Re: DeHavilland DH90 Dragonfly

Postby Steve Rickett 2333 » February 6th, 2016, 6:14 pm

The weather has been pretty reasonable the past few days. Well, good enough to get a spot of painting done. It's all tucked up in the warm workshop hardening off while the next storm hits!!

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Phil Clark
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Re: DeHavilland DH90 Dragonfly

Postby Phil Clark » February 6th, 2016, 7:46 pm

Looks fantastic mate......love the colour.

Phil

Paul Williams
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Re: DeHavilland DH90 Dragonfly

Postby Paul Williams » February 14th, 2016, 5:54 pm

Beautiful, one of my favourite aircraft

Steve Rickett 2333
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Re: DeHavilland DH90 Dragonfly

Postby Steve Rickett 2333 » March 18th, 2016, 5:13 pm

I've still got a few jobs to complete, but it's had its final inspection and sign off!

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Glazing, registration and then cockpit detail still to do! I'll probably leave the lettering and cockpit detail for now, but I think I ought to glaze that canopy before I have a go at flying! The Kolm EZ50's engines have been run (they've both had 50 flights each in my Thunderbolt, so should be nicely run in now). I'm quite pleased with how well sync'd they are. I'm still making final needle adjustments, but I'm nearly there.

All-up weight at the moment is 28kgs (62lbs) and I'll probably add another 1-2kg with cockpit detail, pilot and glazing etc but it's, quite unbelievably, exactly on estimate!

Paperwork is in the post to Tony Hooper, once I have the Certificate to Test off the CAA then we'll be able to go out and get some daylight under the wheels! Fingerscrossed for some nice weather!

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Re: DeHavilland DH90 Dragonfly

Postby Alan Cantwell 1131 » March 18th, 2016, 7:11 pm

Simply the best, superb!

graham trever
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Re: DeHavilland DH90 Dragonfly

Postby graham trever » March 19th, 2016, 9:53 am

Hi Steve
Your workshop not as fancy as mine with carpets and fireplace but certainly turns out very smart models.Looking forward to seeing it fly and might be there at testing if I know when and were.Look forward to seeing you soon maybe at easter.

Bob Thompson1894
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Re: DeHavilland DH90 Dragonfly

Postby Bob Thompson1894 » March 19th, 2016, 1:22 pm

You never fail to impress, Steve. Look forward to seeing it in the air.

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Simon Lawson
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Re: DeHavilland DH90 Dragonfly

Postby Simon Lawson » March 19th, 2016, 4:16 pm

Fantastic Steve. Looks beautiful!

Peter Siggins
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Re: DeHavilland DH90 Dragonfly

Postby Peter Siggins » March 20th, 2016, 8:54 am

Fabulous Steve,

All the best for the maiden

Pete


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