Author Topic: Dave's Large scale EDF Concorde build thread (Read 1727 times)

warbird_fanatic · « **on:** June 09, 2012, 19:28:40 PM »

Hi Guys,

Following on from my other thread, I thought it would be much better to do an official build thread :-)

So to start off,

Today the Mrs went on a 20 mile walk which gave me 7 hours of man time to make my office a complete mess with polystyrene!
To build the fuse, I used 6 insulation blocks measuring 4 foot x 10 inch by 5 inch, building them up 2 at a time with some epoxy (lots of) to the point where they were all joined in a row, At first it was a complete PITA to fix them all together to cure, I then thought about using some rigging rope at either end and used it to pull the blocks together for a tight seal - It worked a treat!
I then got the wood saw out and started to shape the plank into a fuselage, then got out the kitchen knives which were razor sharp and I began to shave away piece by piece until I could get the shape that was required, The nose will be made from a separate piece to bond later on once the fuse is smooth as silk which will make the length around 15 foot in total, In the photo you can see the length is 12 foot and I'm loving it, the size meens I can use it as Turbine based platform later on if required.
Still awaiting my 2 hobbyking orders which are in the UK but parcelforce haven't sent the 'you owe customs charges' slips
The concorde is going to be powered by 4 x 70mm Pusher config EDF's each pushing out around 1700g's of thrust, I'm aiming for a maximum AUW of 4 kilos, to work this out I literally put all of the components, ancillaries, epoxy, carbon fibre etc onto a Vet's scales to weigh it all and it's coming out at 4.5 kilos, the heaviest component overall will be the batteries which weigh 600 grams each (2 will be used, 1 per 2 EDF's)

I really can't wait to get it in the air, I would think around 2 months of weekends and she'll be ready, It's just a case of smoothing out the styrene, then lay it up with carbon fibre and 30gsm GF tissue and she'll be solid :-)

And for the true fans out there, I'm even adding a retractable tail wheel and thrust reversers, there's also 3 crew members on order for the cockpit which work out at 9cm's tall each, the Mrs is making the uniform on her sewing machine :-)

warbird_fanatic · « **Reply #1 on:** June 09, 2012, 19:35:49 PM »

Forgot to add the photos!

dd1961 · « **Reply #2 on:** June 09, 2012, 20:54:44 PM »

wow...looking forward to seeing the end product!!

dogshome · « **Reply #3 on:** June 09, 2012, 22:53:24 PM »

Nice mess!

dom · « **Reply #4 on:** June 10, 2012, 07:42:00 AM »

Good work.

warbird_fanatic · « **Reply #5 on:** June 10, 2012, 10:56:04 AM »

The most annoying thing is I'm having to work backwards by building up the Fuse first, you'll notice that where the wings join the fuse on a Concorde, it flattens out whilst my fuse is still the tubular shape, Basically once it's all shaped, I'll then build the wing joiner and bond it on, hollow it out for the undercarriage then make the wing joins which will probably be carbon tubes slotting into larger tubes with a few neodymium magnets for back up, the Fuse will be laid up in GF tissue and the areas where movement / weakness will be laid with 90gsm 2x2 carbon twill, the wings will be foam carbon veneer for strength, I really don't want too much wing joint flex if I'm planning on a turbine conversion later in the year.
Eventually, depending on how I feel, I'll then remove all the gear from the concorde and run it through a band saw into 2 so I can then make a mould and possibly sell a few composite kits, Don't have a clue how much to charge for such a thing, I think the scale works out at 1/10 at 16 foot long? :-)

warbird_fanatic · « **Reply #6 on:** June 12, 2012, 23:04:02 PM »

Got down to a bit more of the sanding yesterday evening, had to stop though, totally forgot about Health & safety, had asthma most of the evening due to the poly dust in my lungs, eyes, ears, hair, it even reached places where the sun doesn't shine!!

warbird_fanatic · « **Reply #7 on:** June 17, 2012, 12:05:35 PM »

Just finished making the rear wheels

Started laying the GF cloth over the fuse so it's becoming stronger everyday

warbird_fanatic · « **Reply #8 on:** June 17, 2012, 20:16:05 PM »

Just finished adding a bit of tissue to the top side for strength, Someone thought it was a surfboard on top of the car!!

The Codfather · « **Reply #9 on:** June 17, 2012, 23:15:52 PM »

Certainly is looking like a huge challenge!!

rogerandout · « **Reply #10 on:** June 18, 2012, 09:11:11 AM »

it aint gonna fit in that car

Yoyo · « **Reply #11 on:** June 18, 2012, 14:29:24 PM »

It's Concorde - the nose bends out of the way!

warbird_fanatic · « **Reply #12 on:** June 18, 2012, 19:39:34 PM »

No challenge is too big! Nose hasn't been built yet, what you're looking at is the complete fuse exc the nose on the right, the tail has the end attachment which will be put on later with the rear strobe to be fitted, then it's in with the wing mounts and undercarriage, rear tail wheel, then the cockpit & nose :-)
I would say another 6 weeks and she'll be in the air, unfortunately one of the ESC's blew up instantly when it was armed with the throttle so it's off to the QC's at hobbyking, We'll get there eventually, I just sincerely hope the rest won't burn up in flight otherwise it will look like the Air France disaster - If it did happen, it wouldn't be put on youtube, I can't imagine the comments I would receive or the death threats etc! I just really want to get this plane in the air, It's my largest build to date!!

warbird_fanatic · « **Reply #13 on:** July 02, 2012, 18:28:10 PM »

It's been a little while since I posted, Been stuck with this rubbish weather and working heavy hours!
I started on the wings and belly this weekend

For the main structure, I used Wickes insulation boards - 60mm x 1000mm x 600mm and used a foam cutter (modded solder gun) to basically take out chunks of the desired depth then in with the orbi sander to get the correct shape, it took about 45 minutes per wing but it's getting there, Luckily the Wickes boards have interlocking channels so I've reinforced the channels with GRP to which I'll then have several carbon rods that slot in for support. I did a test of the fans on the scales yesterday and wasn't too impressed, roughly about 1KG output from each, Not made any thrust tubes yet so we'll see the outcome once the wings are done, If need be I'll sell the current fans and buy the new Alloy fans from HK as they're getting some good reviews.

Once HK hurry up with their turbine pricing then I can order in 2 of those afterwards!
The most annoying part soo far is i'm having to build the whole bird, then attack it to install the ancillaries and compartments.
Hopefully will get more done this coming weekend!!

dogshome · « **Reply #14 on:** July 02, 2012, 20:42:57 PM »

Looking good (mad) (but good)

Will you be buying a roof rack for the Clio?

warbird_fanatic · « **Reply #15 on:** July 02, 2012, 21:26:20 PM »

That's a Megane mate :-), I think a Clio would gain lift at speed with the Concorde on top!
I'm still feeling a bit frightened about putting the Fuse through the guillotine once completed so I can put it in the back, I think it would look much cooler on a roof rack on the motorway :-D

The Codfather · « **Reply #16 on:** July 02, 2012, 22:13:39 PM »

looks like wickes are a key player in getting this bird airbourne! would they get any promo out of this..job done lol

warbird_fanatic · « **Reply #17 on:** July 02, 2012, 23:02:25 PM »

Lol - It's got their name on it :-D

The boards were £3.99 each, so I bought 10 of them as I'll use them for other projects, Will probably built a large scale A380 next, I'm thinking 16 foot long fuse.
I may sound mad but if you've flown large scale, you'll notice the scale performance is much much better, speeds look more realistic plus the handling makes such a difference with more air under its wings!
Really can't wait to get it in the air, just hope the power output will be enough as I believe the thrust to weight on the real Concorde is around 0.7:1

meharibear · « **Reply #18 on:** September 20, 2012, 15:51:48 PM »

Real Concorde was around 410,000 lbs at take off weight. Thrust was around 4 x 40,000lb = 160,000 so your thrust to weight ratio of 0.7:1 is way out. It looks more like 0.4:1 to me

By the way, an update on progress would be good!

tsr · « **Reply #19 on:** September 20, 2012, 20:17:15 PM »

While Concorde uses at max take off weight as Meharibear says a thrust to weight ratio of .37 the 747-8 takes off with a thrust to weight ratio of .27. However the problem faced by EDF modellers is that while we can build a model with the same thrust to weight ratio as our inspiration it will probably barely fly at such a low thrust to weight ratio. There are exceptions to this but to explain quickly the problem is that dynamic thrust falls in proportion to forward speed and thoretically reaches 0 at the efflux velocity. So a small EDF with 120 mph efflux velocity at an air speed of 40 mph has already lost roughly 30% of its thrust and the airframe drag means that it may never fly more than 50 mph because the thrust isn't there. If you try with 0,5 thrust to weight you will find that it flies but accelerates very slowly and flies really very poorly worse still it slows down very quickly in manoeuvres and loses speed in climbs very quickly that's a drag inertia thing coming into play as well. Move to 0.7 to one and yes you are way over scale but then the efflux velocity isn't very similar to an Olympus either and you do not have to fly at full power all the time do you?

xairflyer · « **Reply #20 on:** September 20, 2012, 21:42:34 PM »

Just seen this, love it!
Have wanted a big concorde model since seeing Ali's fly back in 2006 at Cosford.
two P60's me thinks!

Author Topic: Dave's Large scale EDF Concorde build thread (Read 1727 times)

Follow members gave a thank to your post:

RCMF Team