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Old Oct 09, 2013, 01:20 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
Build Log
Straightforward build from Depron

There's a lot of fun to be had at little fuss or expense. You can buy these EDF units, assembled ready, for 15 to 20. This one at 70mm claims to produce 1350gms of thrust at 450watts.

I've used the smallest one, 220watts in a Messerschmitt 163 Komet effort.

Here's a video:
Komet (6 min 21 sec)


and here's how it started:
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Old Oct 09, 2013, 01:33 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
The key to this idea is the thrust tube and the battery pod. The 64mm unit I'm using gets 5 min of energetic flying time from a 2200 3S1P battery. The minimum size for a pod to hold that battery is 50mm wide and 145mm long. Don't forget some ventilation.

Several different planes could be built from this starting point.
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Last edited by nickchud; Oct 09, 2013 at 03:53 AM.
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Old Oct 09, 2013, 01:55 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
Both models are

36" WS
19.5 AUW
Wing loading on the Komet is 10 oz / sq ft
The Vampire is 12 oz/sq ft.
CG on the Komet is 130mm from the LE at the root.
CG on the Vampire is 65mm from the LE in line with the boom.

Both have rudders but these are optional extras. You get more fun.
Komet uses elevons.
Both have KFm4 (symetrical) airfoils and no dihedral, not for beginners.
The Komet is more stable due to its swept wings.

They fly fast and they're not very big, so I always colour them white underneath.
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Last edited by nickchud; Oct 09, 2013 at 04:00 AM.
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Old Oct 09, 2013, 01:56 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
A simple EDF Vampire (9 min 34 sec)
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Old Oct 09, 2013, 03:30 AM
smithy
jumpy's Avatar
Cornwall, UK
Joined Dec 2004
526 Posts
Very nice Nick, simple but effective. I realy must try out this 'depron', where do you get yours from?. Just bought a couple of Lander 70mm's from brchobbies for my bird, very reasonable too.

Phil
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Old Oct 09, 2013, 03:50 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
Thanks Phil

A good place in the UK is depronfoam.com

For these little models it's a good thing to sand the LE to sharp edges and cover with tape or Solite. They fly faster and they're stronger too.

After sanding, if you want a model to look good, you can wipe lightweight filler across the surface (they call it Spackle in the States), then sand again. A really good finish is this Water Based Polyurathane. You can use it with 0.6oz fibreglass and with cheap water based paints for coloring. It's all waterproof.

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Old Oct 09, 2013, 01:14 PM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
I was out in 19 mph wind this evening with the Komet. There are plenty of trees, hills and dips around here to make the gusts more unpredictable. The plane was rock solid, very easy to manage.

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Old Oct 11, 2013, 03:45 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
We've had quite a bit of strong wind this week. Both planes handle beautifully. You can see that the Vampire is probably less robust because of those booms. However, it got hit by an extra fierce gust just as I was landing yesterday and cartwheeled across the ground. Both wingtips were crumpled from the point where they become just a single sheet of Depron, but that was all the damage. It was easily sorted by ironing flat with the covering iron at medium temperature. I took it out again first thing this morning.

The fun goes on
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Old Oct 11, 2013, 01:11 PM
James L
TANGOSIERRAROM's Avatar
Beck Row Mildenhall
Joined Mar 2009
825 Posts
Nick you are having way too much fun with your Vampires. Is the balsa one still flying?
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Old Oct 12, 2013, 02:50 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
Hello TSR
Quote:
Is the balsa one still flying?
I wish it was. I loved that plane. One windy day I tried to hand launch it. There wasn't anything to get hold of underneath, I was holding it behind the wing and the wind got underneath. It flew up too steeply, stalled and crashed straight into the ground. It's now in my too-difficult pile, waiting for a rebuild.

The little foamy has got something to hold for hand launching and I've learned the lesson..... With EDF always, always launch straight ahead, not up.

Cheers

Nick
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Old Oct 13, 2013, 08:32 PM
James L
TANGOSIERRAROM's Avatar
Beck Row Mildenhall
Joined Mar 2009
825 Posts
Sorry to hear that that was a really nice model for two reasons one you had to iron out the wrinkles in the design and you succeeded and you still had something that looked right and as a Vampire should.
I am having some similar issues myself in that currently I have one model flying it should have been 2 out of the three I usually fly but the cats decided to sit on the orange one and TSR2 is sitting in a room waiting for me to give it a new wing tailplanes and fin.
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Old Oct 15, 2013, 06:05 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
4,023 Posts
Here's a link to the last page of the build thread. You're right, it was a lovely model. I'm now more convinced than ever that the only real source of difficulty was trying to fly with a too rearward CoG. When I used the CoG calculator I didn't allow for any extra effect caused by the large air intakes. Now I believe they must have a kind of bi-plane effect, moving the Neutral Point forwards. Whatever it was, every version I have built required about 10% more static margin than you would normally expect.

Good luck with the TSR2, that's another classic jet plane.

Here's another suitable subject:
Concorde second flight (5 min 36 sec)
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