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Fairey Delta 2 in Depron

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Simon Chaddock10/08/2013 18:23:29
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The FD 2 was certainly a 'fast' jet. In 1956 it held the world speed record at 1132 mph.

FD2 in flight

Always only a research plane (3 built, 2 flown, one for structural test) it was basically a 'dart' with a simple circular fuselage wrapped around an early after burning RR Avon.

FD2 3 view

Note the intakes are 'simple' with no moveable intake body to make use of the supersonic shock wave and the relatively small tail pipe sized for high speed flight rather than static thrust.

The result is the total inlet area is actually slightly larger than the tail pipe, good for an EDF but it will mean a relatively small unit for the size of plane.

A novel feature was the whole nose and cockpit 'drooped' to give the pilot a reasonable view for landing.

My intention is to mount the EDF right at the back, it will actually be the tail pipe as this means the high velocity duct will be as short as possible.

Sized for a 55mm EDF tail pipe the FD2 will have a span of 30" (762mm) and be 58" (1473mm) long.

The final twist is the entire airframe will be made of Depron and only Depron with no reinforcement at all! smile o

A modest start. The fuselage tail cone.

Tailcone Duct


Another 'vertical' build in 2mm Depron.

Over this section the duct tapers from the 55mm diam of the EDF to 66mm (the area of the inlets) so it is built using planks.

The completed duct with the EDF unit perched on the end.

Tailcone and EDF

The fuselage outer skin itself will only be completed when the plane is complete and all the electrics installed.

Edited By Simon Chaddock on 10/08/2013 18:25:37

Mart4910/08/2013 20:53:45
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Simon, having played with some depron over the last few months, I'm always staggered at what you can acheive when you build. Looking forward to this one. Mart

Simon Chaddock11/08/2013 13:44:52
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The fuselage centre section duct with the tail cone section just resting in place..

fusecentre1.jpg.

As the duct is a constant diameter the duct has been formed by wrapping a 2mm Depron sheet around the rainwater down pipe 'mandrel'. The edges are joined by a scarf joint.

As the FD2 has a relatively small wing and a delta at that I belive the wing needs no spar and can rely entirely on the wing skin as the stressed structure with a number of Depron webs to take the shear forces between the skins.

Wing shear webs

Flat at this stage but each web is sized to give a very thin (4%!) symmetrical section when the top skin is glued on 'free hand'. Sounds an odd way of wing building but it works. smile o

The issue is how to transfer the forces from the wing into the fuselage which with inner and outer skins is itself a stressed skin structure.

wingfuse.jpg

To do this the wings will be fixed to both the duct wall and the outer skin with the fuselage formers exactly lining up with the wing shear webs. The completed wing glued to the duct.
Wing on duct

Second wing and top and bottom fuselage formers added.

Fuselage formers


The weak point in the wing/fuselage joint are the inlet ducts which are very thin walled to give maximum inlet area so provide limited support to nearly the first third of the wing. Fortunately the area involved and thus the loads are small as well.

The next stage it to construct the inlet ducts which will have complex double curves.

Erfolg11/08/2013 13:55:48
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Simon, you must let me know when you fly this model. So that I can come along, or perhaps at our field?

Regards

Carl

Simon Chaddock12/08/2013 00:22:13
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Erfolg

Will do but the first flight is still some way off! wink 2

Simon Chaddock13/08/2013 13:13:16
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Part of the fuselage nose section inserted to form the inner walls of the intakes.

Fuselage Intake

The original duct wall is then cut away to allow the bifurcated duct to be built up .

The lower part of the duct completed.

Intake duct start

Very slow progress as the planks have both a complex shape and twists requiring much 'trial and error' dry fitting before being glued in place.

The top half of the duct will be even harder as access will be much more restricted. frown

At about this point with more hours spent so far on just one part of the inlet duct than on the rest of the airframe so far you begin to doubt the wisdom of even starting! wink 2

Swissflyer14/08/2013 17:48:59
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Very nice project, I have had the Fairey FD 2 on my possible projects list for some time, so will follow with great interest.

Good luck with the time management wink

Mark

Willowlea14/08/2013 23:32:09
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Ah will be fine Simon, you worried about the V1 being a long project and going banana shaped and it all turned out brilliantly in the end, am sure this will too smile

Simon Chaddock15/08/2013 00:27:49
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The very fact that the previous planes have worked out reasonably well increases the risk that sooner or later there will be one that won't! wink 2

For a bit of relief from the inlet ducts a start is made on the cockpit section. No duct to worry about here! teeth 2Nose section start


As it is basically symmetrical it can built vertically. Initially with just 3 planks but once all the formers are in place the planking is progressed equally on both sides.

There is another 10" of nose still to add. But as it is so long and thin it will maiden with a simple Depron 'nose block' in its place.

Edited By Simon Chaddock on 15/08/2013 00:28:38

Simon Chaddock16/08/2013 01:08:52
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The nose section complete or rather as far as is possible until the electric go in.

Battery compartment

The battery compartment is sized for an 1800mAh 3s.

With the 3 section stacked up you can get an idea of what it will look like.

3 sections.

And there is another 10" (25cm) of nose still to go on. wink 2

The wings will look quite a bit larger when the the big elevons are added.

Ade Eades (Eadsie)16/08/2013 07:43:10
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17 photos

Thats Amazing!, i will be watching this with gusto......thats got to be the lightest airframe ever (for scale) well done, whatever next

Colin Leighfield16/08/2013 08:12:13
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Wow Simon, that's going to be another winner. Another British lead thrown away by incompetent governments and picked up by the French in the Mystere! Great to see you bringing it back to life. Remember the Veron FD2 that Phil Smith did, in the sixties(?).

Simon Chaddock16/08/2013 20:27:54
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Adrian

Light? yes. Practical? I am sure anyone in their right mind would spend so long on a foam plane!

Colin

It is doubtful if the FD2 had much influence on the Dassault Mystere Delta 550 as it flew less than 1 year later. The obvious performance of the FD2 did probably confirm to Dasault the wisdom of producing the bigger and much more powerful Atar engined Mirage prototype, particualrly as some of the FD2's supersonic testing was actually based in France after the UK government banned such flights in the UK!

Only the EE Lightning got through the 1957 "no manned fighter" defence cuts (and then only just!) so any development of the FD2 was out of the question but as Dassault showed a delta does make a particularly good interceptor fighter. wink 2

For a research plane the FD2 had a remarkably long life with the last flight in 1973 (as the BAC221) some 19 years after is was built.

Colin Leighfield16/08/2013 20:47:54
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Simon, I meant Mirage! My brain must be going, probably influenced by the fact that on Sunday I sat in a Mystere IVA at the Dumfries and Galloway Air Museum. The Duncan Sandys White Paper reflected the same kind of political short-sightedness that we still see now and wrecked a great industry. At least we did get the Lightning, as you say. (There's an F6 at Dumfries as well).

Are you flying the Hamilcar now?

Simon Chaddock17/08/2013 11:41:55
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Colin

The first Dasault delta was intially called the Mystere Delta 550 so you were actually right!

The elevons are huge.

Elevon

Being so big relative to the wing area their total deflection will be small (10 degrees each way?) so I have added a balsa leading edge to provide additional torsional stiffness.

Colin Leighfield17/08/2013 12:41:17
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Good point, I'm really dredging my memory. I know Fairey were working on a larger fighter design based on the FD2 and it was one of the projects that got the axe, along with the others that are painful to think about now, I hate politicians. The balsa leading edge is sensible and I'm sure that the large elevons with limited movement are a better idea than small ones with large movement! You've got a good one there Simon, I'm still incredulous at your workmanship with Depron. I must get my head around it some time, I can see the potential.

On another point Simon, tell us more about your Hamilcar, I'm still fascinated by that one, it looked so good and must make a good flyer.

Simon Chaddock17/08/2013 22:19:57
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Cilon

I am afraid the Hamilcar technically remains un-flown, although crashed and rebuilt - 3 times.

It appears the wing has very poor stall characteristics resulting in an incipient spin with very slow recovery. Each 'flight' only lasted a few seconds before it spun in.

It is currently very nearly ready again but one motor/ESC is playing up and they are permanently built in so yet more cut out/rebuild is required!

This was my first big scale Depron build and I would do things rather differently if I did it again.

I just need to get a round tuit to try again. wink 2

Edited By Simon Chaddock on 17/08/2013 22:20:27

Colin Leighfield17/08/2013 23:14:16
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That's an interesting one, frustrating for you. Trouble is that the likely causes need some major work, particularly on the wing (wash-out)? Might need a smaller test-mule to identify the best options, I bet you're scratching your head at the moment. Thanks for letting me know Simon.

Simon Chaddock18/08/2013 11:27:58
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The elvons under construction.

Elevons in progress

2mm Depron skins with Depron ribs. Its 3mm balsa leading edge adds nearly 20% to the weight but the completed elevon is remarkable rigid.

Fitted with a tape top hinge.

Elevons fitted

The white duct tape is very flexible so the elevon easily drops to the bottom stop under its own weight.

The fin is next.

Simon Chaddock19/08/2013 15:59:11
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The fin added and the final nose section.

The full nose & fin

The nose will get broken in even the mildest mishap that is for sure but my experience with this type of Depron structure suggests it will crush locally leaving the rest undamaged. It is relatively easy to build another nose.

Anyway I wanted to see what it looked like! wink 2

Now to start fitting the electrics.

Edited By Simon Chaddock on 19/08/2013 16:00:33

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