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Old May 24, 2011, 05:29 PM
a.k.a Maltone
Australia, NSW, Goulburn
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I imagine Manzano will kit it - given the usual prerequisites - does it go together OK? does it fly? does Charlie feel like kitting it

Pat
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Old May 24, 2011, 07:35 PM
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Macarthur Region of Southwest Sydney
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Thanks guys for your responses re silver bearing solders. Soldering is not exactly unknown to me, I was an electronics tech for 50 years. All my model soldering was done with 60/40 resin core solder and I've never had any problems with that despite it being the weaker solder mechanically. I agree with Deuce, as none of my joints have failed except as a result of 'incidents' that have seen the model go home in a plastic bag! However my attitude is that if there's something better, then use it. Dick
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Old May 24, 2011, 08:27 PM
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I also use std solder for models, at least up to 9lb. But, I have had a couple joints work loose over time too.

For larger models I'd probably try brazing.

The key is joint prep, no matter which solder you use.

charlie
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Old May 26, 2011, 10:18 PM
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Quote:
Originally Posted by cd_webb View Post
Charlie,
I've got a small arbor press too and had that very same idea. The problem is I can't machine the point or the notches. I would have to have that done at a machine shop. Can't think that it would be too expensive, but you know how it is, some ideas work out better between your ears than in practice.
Would a pic of your setup be asking too much?

David
Sorry it took me so long.

charlie
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Old May 27, 2011, 04:20 PM
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Thanks, Charlie. Downloaded and saved the picture to print. My neighbor 'bout three miles down the road should be able to take the picture and modify my press and fabricate the steel block. Like I said, this thought had crossed my mind before, and now that I know it works...

David
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Old May 27, 2011, 10:42 PM
a.k.a Maltone
Australia, NSW, Goulburn
Joined Jan 2005
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Tail bits....

Nice looking tool Charlie - I must keep an eye out for one (with safety goggles on of course..)

Since Pete has told the world via the June issue of FSM magazine that this will be a 'quick and dirty' build, I'd better get on with it despite having a very severe cold..........

The tail parts were dead easy once the laminated outlines were made. The internal framing is all 1/4 X * but use some harder stuff for the elevator spars. The fin I SHOULD have made 1/4" thick as it is designed as 3/16" to be sheeted - essential if staining, but as I am painting these parts, a tissue or film cover would have sufficed - probably not much difference anyway.

After sanding even all over and radiusing the edges, the parts were hinged and temporarily fitted to the fuselage. I also made up the 1/8 ply tail skid and its support fin - 1/16 ply faced with 1/16 balsa. These parts were tacked together for a photo in the glorious Autumn sunshine! The wheels are obviously temporary but a bit small in diameter.

Pete's design doesn't include wheels - not sure why, I guess there is a good reason But a few ply and balsa discs in the normal manner should suffice.

Now I'd better look at wings I guess (big sneeze.....)

Pat
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Old May 28, 2011, 01:07 PM
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Solder joints

Quote:
Originally Posted by portablevcb View Post
I also use std solder for models, at least up to 9lb. But, I have had a couple joints work loose over time too.

For larger models I'd probably try brazing.

The key is joint prep, no matter which solder you use.

charlie
The problem with soldered joints is that solder has no real inherent strength. Solder is soft and easily fatigues. In a joint where solder is wicked over wrapped wire and struts, the wire is holding everything together and the solder is more of a stabilizer preventing the wire from slipping. If the wire were not there, the joint would fail after a few cycles unless the joint is very lightly loaded.

There is a reason that solder joints in flight electronics (aircraft and spacecraft) are completely unloaded. Wire and components are mounted in such a way that the load is not carried in the solder. Why? Solder is soft and ductile and will fail under even light cyclic load.
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Old May 28, 2011, 02:27 PM
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You are correct. Solder joint on LG is really a wire bound joint stabilized with solder.

A lightly loaded LG can last for a thousand cycled. A heavily loaded LG will only go a couple hundred.

For highly stressed joints brazing is the way to go.

charlie
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Old May 28, 2011, 03:58 PM
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Ah yes, the wheels. Well, I'm sure there was a reason too, beggared if I can think of it now though. Probably to do with the diameter not fitting on 4" wide balsa and me being too mean to suggest 6" wide sheet for just those parts.
Could also be that I thought the weight and strength of commercial wheels might be of more use.

I just checked and it doesn't seem to be the first reason, must be the second - or that I forgot them.

Pete
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Old May 28, 2011, 08:32 PM
a.k.a Maltone
Australia, NSW, Goulburn
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More Wire....

No worries Pete - the DVII is in the same boat so I'll do an hours or two making balsa and ply discs

A bit of a curve ball (or googly for cricket fans) in the centre section struts. They form a double bipod fitting to the wing along its underside centre line. The plan shows the side view and the cross-section views but not the 'this-is-how-you-bend-it' view. Easy to work out though - I just drew what the ACTUAL wire lengths needed to be on the plan (red pen) and carefully bent the 14swg wire accordingly. The bends are in 3 dimensions and so some care and understanding was needed to get it right. A single 36" length of wire cut in half was enough and the two top bends were made to fit the modified plan.
Then the ends which fit into the cross-tubes were bent using the modified cross view with the centre length being held at right angles to the plan as and aid to getting it right. And it did......

The two half-struts were inserted in the fuselage tubes and brought together - they were over the centre-line and at the right height at front and rear - the front higher than the rear to set incidence.

Whew! - this little exercise would need some setting up for a vendor offering bent wire in a kit........

When finally fitted, the tops will be bound and soldered and will clamp to hard points under the top wing.

Pat (off to think about wheels)
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Old May 29, 2011, 03:02 AM
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Pat,
You did it exactly as I envisioned it being done. Having a view on both front and rear struts, and knowing the length between them, it should all work okay. However, for the faint of heart, or those who don't feel up to the accuracy required throughout the multiple bends, the centre length could be replaced by brass tube. So you just bend back/forward the ends of the front/rear struts and join them in the tube.

Pete
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Old May 29, 2011, 11:42 PM
a.k.a Maltone
Australia, NSW, Goulburn
Joined Jan 2005
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Wheels...

The wheels are absolutely standard Peter Rake style - two 1/16" ply cheeks and a 1/4" soft centre - I used 1/4 5-ply bass for the centres but balsa would be more normal. The hubs are 1/8 ply each side with a 3/16" brass bearing tube. Tyres are 1/2" (maybe a trifle small) rubber cord cut in a simple jig to get the ends nice and square and glued with ZAP ca designed for rubbery stuff.

She now looks to be about 19" high when completed!

The bench and workspace has been cleared ready to start the wings.....

Pat
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Old May 30, 2011, 12:05 AM
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Australia, WA, Ellenbrook
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Definately an odd looking beast this one! Those crazy Germans, for every beautifully proportioned classic they produced during the two wars, there was and equal number of odd bods that only a mother could love. Coming along very nicely Pat.

Cheers
Craig
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Old May 30, 2011, 07:03 AM
a.k.a Maltone
Australia, NSW, Goulburn
Joined Jan 2005
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Yes - she sure is an odd one Craig - only its mother and Peter Rake could love it

Peter has designed the plan so most parts of the wings could be built simultaneously IF your building board was big enough but I've decided to do the much simpler lower wings first but get all the laminated tip curves done. While I was at it, the lower ribs, spars, LE and TE etc were got together and maybe tomorrow it will be done!

Pat
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Old May 31, 2011, 10:11 PM
a.k.a Maltone
Australia, NSW, Goulburn
Joined Jan 2005
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On with the Wings..

All the bits were set up and fixed together as has been described in Rake builds here for years..
About the only deviation is the method of fixing the I/P struts. These struts are fastened to the 1/8 ply ribs with small brass strips with a brass nut soldered over one hole. Because all the screw holes in the ribs and struts are pre-cut, the strips need to be reasonably accurate. While soldering the brass nuts to the brass strip, they were held loosely in place with a RUSTY steel bolt - the rust doesn't solder so well! My usual silver-bearing solder was used.
These big IP struts will be rounded off and canted outward at an angle when fitted.

The upper wing I am building in one piece so the pin board was extended a little! The 3/8 X 3/16 spars were joined at the centre with 1/8 ply 'diheral' braces - except that there is no dihedral From there on it will be plain sailing.....

A variation from the drawn plan OKed by Peter was to fit balanced ailerons. This is because the aircraft I am building had straight ailerons with DVII-style balance extensions. From what I can glean from photos, these ailerons were added without changing the main wing shape so all that is needed is a re-shaped aileron - no problemo! I'll even use most of the supplied parts. The drawing is marked up in red pen showing the variation.

This 'other' version of the DXI has a mauve and green fuselage rather than varnished ply. It also sports a HUGE 4 blade prop (different engine) but unfortunately, it still has lots of lozenge covering............practice for the Fokker DVII some day

Pat
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