A scale EDF Concorde...... in Depron!

[Simon Chaddock]

This really is a follow on from my 'scale inlets' Depron EDF Fairey Delta 2, an EDF Concorde with scale inlets and exhaust.

My idea is mount two 40mm EDFs right at the back of the inboard engines and then scale the rest of the airframe around it. It comes out at 36" span and 90" long.

A 40mm EDF can just about manage 6oz thrust on a 3s so to stand much chance of flying this 7ft 6in long Concorde will have to weigh no more than 20oz!

And just to add to the challenge it will also have a true scale wing, or as near as I can make it.

The first task is to prepare a 3 view with all the unwanted surface detail removed to act as a plan.

For transport 27" of the nose (and probably the tail cone as well) will be removable.

The more i look at it the more I wonder if this will be a "Depron" step to far!

[Tony Bennett]

i have a full set of plans for this beast sitting in the workshop, just never got round to starting it.

best of luck with it simon.

[David Tweddle]

I will follow this one Simon.

Thanks

David

[riverlandgirl.]

Looking forward to this, always been a bit smitten by the concord.

[Stefan Hafner]

Looks interesting, will be watching

[Piers Bowlan]

I know to many this would be scale sacrilege but have you considered a couple of 70 mm fans instead and sacrifice scale authenticity for performance and a stronger more robust model as weight won't be so critical?

Always wanted to build a Concorde, quite a challenge. Good luck Simon.

[Simon Chaddock]

Piers

Of course I could use bigger EDFs but the whole object of this exercise is to demonstrate that with care it is possible to build a true scale EDF at a reasonable size, without breaking the bank and still achieve a worthwhile performance.

We shall see.

[Depron Daz]

Can you stretch to 50mm units? It will be a slight increase in build size but may get you a slightly bigger envelope for power/weight ratio?

There are some gorgeous Concorde's being built over in RCG if you haven't seen them **LINK**

I'm grabbing a bag of popcorn and pulling a chair up for this build, good luck Simon

This bird is on my "possible" build list.............

[Simon Chaddock]

Depron Daz

To go to 50mm would mean an increase of 25% in overall dimensions and I am already concerned at the rigidity of that pencil thin 90" fuselage in Depron!

If I can achieve my target weight I should (or is that hope!) it will have a reasonable performance with 40mm EDFs.

If they do generate 6oz thrust each it will give a thrust to weight ratio of 0.6:1 and my EDF Fairey Delta 2 flies pretty well on slightly less than that.

The nose section plan printed out to size. The joint will be at the red line

The first of the formers.

This will be a 'minimum' type construction with no keel or internal support, just formers and skin.

The full set of formers weigh just 1/10 oz (3gm)!

[Tony Bennett]

looking nice so far sir, keep going.

[Simon Chaddock]

The first planks on the nose section.

As the skin is so thin each plank is curved to match the former. This should give a fairly smooth cross section rather than a series of 'flats' so should require much less sanding.

[Simon Chaddock]

The skin complete on the half shell and the other side formers added.

Although the shell is quite strong it is still pretty flexible in torsion so the remaining planks will have to added carefully to avoid building in a twist.

The half shell weighs 0.64oz so on target for sub 2oz when complete.

I built a small test rig (out of Depron of course!) to measure the thrust of the 40mm fan.

The fan delivers 5.2oz on a 2S drawing 13A which is close to its continuous rating of 14A.

A short 2 second burst on a 3S showed 8oz drawing 22A but the motor burnt out in the process! 

So 2S it has to be. This will give a bit less total thrust than I had anticipated but hopefully the lighter battery will compensate for it. . 

Edited By Simon Chaddock on 12/12/2013 22:52:04

[David Tweddle]

I must start playing with foam.

You got me hooked Simon well done and thank you.

David

[Keith Simmons]

Looking good Simon

Have you worked out the total thrust with the whole intake built? I feel with further losses due to the intake inlet to the fan, close to 5oz? perhaps as low as 4.5oz? will be very interested in the actual results.

Many thanks Keith

[Martian]

I will be following with interest Simon incidentally how do you decide on the former curvature at the moment I can't get my head round it,when using line drawing there are very little reference points for former shape go on Simon give me a clue

[Simon Chaddock]

Keith

The FD2 with a long but inlet twice the FSA lost about 15% static thrust.

The Concorde inlet duct will be proportionally shorter and with both inlets feeding one fan the losses should be slightly lower. I could live with 4.5oz per fan.

The nose section has come out 25% lighter than I had anticipated.

It is eerily light to hold but nevertheless strong and rigid.

Using its weight (1.5oz) as a guide I can 'guestimate' the bare airframe at 9oz. This could mean a flying weight of less than 18oz with an 1500mAh 30C 2s.

With a wing loading of under 6oz/sqft it should still fly even with only 9oz thrust.

Martian

The basic former shape for the majority of the fuselage comes from the head on view.

The rest of the nose formers are 'extrapolated' from this basic section to give the required height and width shown in the top and side views, taking into account the cockpit windows and ending in a circular section at the radome. The same sort of thing will be required for the tail.

I would not claim it is accurate to a fraction of a mm but I bet it was in principle the same sort of process that created the original fuselage shape!

[Martian]

Thanks Simon and what about a more complex fuz shape ?

[Keith Simmons]

Many thanks Simon. Will follow with interest. Regarding the front view, Does the tailing edge of the wing meet the bottom of the fuselage? Trying to understand the lower lines between the engines. Maybe that's why I buy a plastic model for reference. Trying to fix a smilie here. Went to the start !

[Simon Chaddock]

Martian

With a more complex shape you have no choice but to have sufficient cross sections although you can extrapolate between them.

One reason I built my Cessna O-2 was I found a 3 view with 8 fuselage cross sections. It would have impossible without.

Keith

I prefer photos if possible (models can be surprisingly inaccurate) and of course Concorde was very well photographed!

Its underside is quite interesting.

This is a preproduction version with the short tail section.

[Electriflier]

Innovative and inspiring - subscribed!

[Concorde Speedbird]

Great to see my inspirational aeroplane being built. Most RC Concordes have two things that look wrong, the engine nacelles (which you are doing well) and the nose/visor. Your one looks good. I will be interested to see how you tackle the wing. I want to do a balsa Concorde one day.

CS

[Martian]

Thank you Simon I figured there was no easy way thankfully the aircraft I'm planning the 3 view features fuselage sections just got to enlarge and keep clarity or subscribe to site it's on.

[Simon Chaddock]

CS

Ah! The wing. When I have worked out how to do it I will let you know.

If you build a Concorde just remember it is likely to be big.

Just 36" span (915mm) but longer than a bed and that's with tiny 40mm EDFs!

[Concorde Speedbird]

Yes, her dimensions mean that length rather than wingspan is the large number! Having a removable nose section is a very good idea. I'll probably initially go for a hand launched double pusher prop one initially, then try a slightly larger one with retracts and maybe a droop nose.

CS

[Keith Simmons]

LOL, with the model being inaccurate, Had brought a 1/48th TSR2 Airfix kit and the result just does not look right !! Many thanks for the informative underside photo of Concorde. Never knew it looked like that within the wing area.