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Curtis Condor biplane twin

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Geoff S23/11/2020 22:14:00
4025 forum posts
68 photos

That's useful to know, David. It would also be useful to know which variety of supermarket so I can 'visit' and 'rescure' a few bits of liteply (or poplar) for future use.

When I was sailing 12'6" dinghies a club member used to use mahogany from packing cases for some of his builds. This was over 30 years ago so repurposing wood is not a new idea.

Geoff

David P Williams24/11/2020 12:52:54
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933 forum posts
332 photos

Another silent watcher here too David. My next project when (if) the current one is off the bench is another biplane twin, a 1/6 DH89a Dragon Rapide, which is also an older, overengineered, one piece (96" wing plan, so I'm particularly interested in how your split detachable wing solution works out. The Rapide wing is really thin, only 15mm or so, so joiner arrangement will be 'interesting'.

David Ovenden24/11/2020 15:49:09
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485 forum posts
93 photos

Geoff, boxes just were piled outside the local (independent) greengrocer shop. Its only one shop so little use to anyone. In any case, the boxes never seem to be the same. Nearly always they are made from thin MDF. But when I spotted these, I thought they might be useful

David Ovenden24/11/2020 15:56:18
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485 forum posts
93 photos

Hi David,

I had the plans for a 96" DH Dragon (not the rapide) but sold them on a while back as I decided to do the Condor - and one big twin biplane was enough for me!

Good luck with your project. 15mm is not much depth to play with. But with a biplane, if the rigging is functional, it needed have massive joiners. I am lucky with the Condor that the wing is semi- symmetrical so there is a little more depth in the ribs to play with.

David Ovenden25/11/2020 18:59:48
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485 forum posts
93 photos

I ended up making up 4 lightweight strip wood formers to help join the fuselage sides nice and square. Otherwise it was just relying on the 1/4sq crosspieces to hold it all true! Next is to cut out all the side and top former shapes and fit all those stringers. Sorry about the poor photo quality.

fuselage joined cropped.jpg

Eric Robson25/11/2020 20:01:00
542 forum posts
124 photos

Going together nicely David , I built a 48" span Hurricane from my own drawings and made the formers plain just marking the position on the first and last. I then laid the stringers on and glued them in place it worked fine.

Bobs suggestion would probably be better for yours due to the size,

Edited By Eric Robson on 25/11/2020 20:04:54

David Ovenden27/11/2020 15:41:13
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485 forum posts
93 photos

Started to add stringers to the underside of the fuselage. I used a notched former at the wing seat but the rest were smooth. Seems to have worked fine. When everything is properly dried I can think whether the stringer/former joint need reinforcing. Currently I'm thinking it won't be necessary.

fuselage stringers.jpg

Also started carving the tail seat blocks so I can sheet/plank the rear fuselage lower tail section.

tail seat.jpg

David Ovenden01/12/2020 16:48:41
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485 forum posts
93 photos

Progress been a bit slow. I have stripped 3 sheets of 1/8" balsa to make the many stringers that will be needed. Soldered up the connectors onto the ESC and motors and made some progress with cutting out the side/to formers. In the end I opted for a mix of notched and smooth. Notched at the both ends of a "run" and smooth in between.

fus side formers.jpg

David Ovenden05/12/2020 13:09:00
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485 forum posts
93 photos

I am getting a little frustrated now because I really need to get on with building the wing centre sections so I can make progress on the fuselage. I need the lower wing centre section to line-up and finish the formers and stringers under the fuselage. And the top fuselage stringers can't go in until I've got the top wing centre section so I can fit and align the top wing structs that are bolted to 2 of the top fuselage formers.

AND.. I can't build the wings until I have the carbon fibre wing tubes that align and are integral to the wing build. I have been waiting 4 weeks for HK to deliver them from the EU warehouse. So its not as if its a delay from the HK warehouse.

In the meantime, I have finished off the underwing formers and components that support the undercarriage. I have also laminated some 3/16" "beams" that take the wing bolts but have to conform to the fuselage underside curve. I made a jig from a piece of old oak fence post and laminated 3 layers of ply to get the correct curvature.

formers in box.jpg

You can see that I have been able to use some upcycled wood from a "fruit crate" for a few parts.

underwing side .jpg

Fuselage section that will fit onto the lower wing centre section. (once I can get it built)

underwing with mount bars.jpg

The long beams will bolt the lower wing to the fuselage. They are fabricated from 3 layers of plywood.

wing bolt beams.jpg

Wing bolts beam being laminated on fence post former!

Edited By David Ovenden on 05/12/2020 13:10:41

David Ovenden05/12/2020 13:11:53
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485 forum posts
93 photos

Also couldn't resist a quick "play" to see how the tail assemblies look in situ.tail 2.jpg

Dwain Dibley.05/12/2020 20:18:42
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1692 forum posts
1641 photos

The obligatory "Dry fit" David, it has to be done Matey. wink

D.D.

David Ovenden12/12/2020 13:13:37
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485 forum posts
93 photos

Still no sign of the carbon wing tubes from HK so I ordered some more from another supplier. They arrived this morning, so I have managed to start the lower wing centre section. Hope to get the top sheeting on later.wing cs 1.jpg

David Ovenden12/12/2020 15:25:16
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485 forum posts
93 photos

Top sheeting on.wing cs 2.jpg

David Ovenden14/12/2020 16:01:52
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485 forum posts
93 photos

Wing tubes all epoxied in, spar webbing fitted, pull cords for motor wires done, and lower wing centre section sheeting completed.

Next step is to trial fit to fuselage and build on lower formers, add stringers to the underbelly/ and add the wing mounting beams

wing cs sheeted.jpg

Edited By David Ovenden on 14/12/2020 16:04:45

David Ovenden14/12/2020 20:52:31
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485 forum posts
93 photos

Duplicate deleted

Edited By David Ovenden on 14/12/2020 20:53:35

Geoff S14/12/2020 23:53:47
4025 forum posts
68 photos
Posted by Dwain Dibley. on 05/12/2020 20:18:42:

The obligatory "Dry fit" David, it has to be done Matey. wink

D.D.

It's a waste of time, really, Dwain, but it's impossible to resist. We claim it's a check but, in fact it's to encourage us to keep construction progressing. I'm as guilty as the next

It's looking stunning, David.

Geoff

David Ovenden15/12/2020 07:54:44
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485 forum posts
93 photos

True Geoff, "dry fitting" is seldom really needed. As you say it's more a morale booster, especially when there's lots left to do on a project.

A question for biplane lovers. The plan doesn't mention washout. Is it worth adding a couple of degrees on a big biplane like this? It has parallel wing chord and the lower wing has less span the the upper - so I'm inclined to think it doesn't need washout - but anyone got experience with a similar model. I haven't incorporated on my other biplanes (Tiger Moth, Hawker Tomtit, Sopwith 1 1/2 Strutter etc)

Eric Robson15/12/2020 08:30:05
542 forum posts
124 photos

Hi David, the Hawker Fury also has parallel chord and a smaller lower wing and there was no washout on the plan ,nor did I build any in and it has been fine.

David Ovenden15/12/2020 11:40:42
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485 forum posts
93 photos

Thanks Eric,

That confirms my thinking. I have been sorting out a building jig to give me the correct dihedral when setting up the wing tubes in the outer wing panels. There is 2 degrees dihedral and I have gone for zero washout. I hope to start building the first outer panel later on today.

Edited By David Ovenden on 15/12/2020 11:41:33

David Ovenden15/12/2020 17:19:08
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485 forum posts
93 photos

Made a custom board (with correct dihedral to build the wing tip panels on) to make aligning the wing ribs and with the wing tubes easier.building  board for wing.jpg

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