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        Discussion Vulture 3500 E glider build

#1 Tony Fu Nov 26, 2011 04:39 AM

Vulture 3500 E glider build
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I believe I have the first electric versions of the new Vulture made by MVM in Bulgaria. I'll be doing a build thread.
The Vulture F3J is featured here in http://www.rcgroups.com/forums/showthread.php?t=1381844
Its 3.5m of gorgeous competition thermal design.
The one I'm building is the full carbon version (65g carbon) but with new electric fuse. In comparison to the glider, the E fuse is considerably shorter in the nose but the same boom length.
There are two lay up options , the other is carbon D-box wing. Both are priced extremely competitively especially for a Euro model.
I am spec'ing the install with light gear and adequate but relatively low power at approx 450w and hopefully 90-100w per lb. The good thing is I've found this is not a problem with a light weight set up using a Hacker A20 6xl and 3s 2200 as my main concern was getting a reasonable CG range without doing anything too drastic in shoving everything up front.

#2 Tony Fu Nov 26, 2011 05:09 AM

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Here's some specs and piccies from the manufacturer attached.

Empty wt of the Vulture E full carbon is 1.52kg
I am putting in MKS 6125 H in flaps and the new MKS 6100 (9.5g) in ailerons and fuse. To maximise the perforamnce and longevity of the wing servos I am using an external bearing kit.
The power system is a Hacker A20 6XL on 16x10 with 3s 2200 Hyperion 45c G3.
Esc is a Jeti 77 and using a separate Ubec (Hyperion cool bec).

#3 Tony Fu Nov 26, 2011 05:21 AM

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Here's the business end

#4 Tony Fu Nov 26, 2011 05:41 AM

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More of the power system.

What has kept me thinking is getting the CG. I wanted to keep the servo position under the hatch in the bottom of the fuse so everything else needed to go forward. With a heavier motor its less of an issue. There's lots of room spinner is 38mm but 40mm outrunners can fit easily because of the nose taper.

#5 Tony Fu Nov 26, 2011 06:01 AM

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Fuse servos located under a opening at bottom of fuse. This makes things so much easier. The snakes are already factory fitted and supplied with servo tray. I made a new one though to fit these tiny new MKS6100. Incredible piece of kit for such a small servo.

One of biggest problems with E glider installs is amount of wiring. No problem here as access is so good.

#6 Tony Fu Nov 26, 2011 07:07 AM

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A design feature of the Vulture is a relatively large tail. It's nicely done and incredibly light at sub 40g per side. Unusually, the elevators do not have a hard hinge line. The skin is backed with peel ply as is the norm but it flexes. The ball links or inserts were not supplied or fitted but there is a nice moulding pre drilled for you. I used pretty standard 2mm balls and some nice threaded 303 grade stainless steel pushrods, cut down as inserts. I had to use a syringe to squirt in thickened epoxy so that the inserts were bonded to the top skin and not just the bottom skin moulding. These bits are not supplied.
Only other job was to glue in single 2mm incidence pin (supplied) and open up the corresponding hole in the fuse to 2mm (undersized but factory drilled). As single hole easy to adjust incidence if needed after test flying. A tail cone finishes this end.

#7 Tony Fu Nov 26, 2011 07:41 AM

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The wings have really nice metal horns factory installed, driven from the top surface. The are shaped so that some portion goes in between the skins and are a good if initially tight fit to standard 2mm clevises using a 1.6mm diameter pin. The recesses on the skins and wipers are factory done too but both need adjusting to allow clevises to go on and so that you get unrestricted travel. Not much though and I tried very hard to keep any adjustments small. It really is pretty clean and not much hangs in the air. The surfaces, flaps in particular are huge. Some thought and design has obviously gone in here to produce a clean linkage. Just a light fettle to one flap wiper was needed and all moved to full deflection without anything catching.

#8 Tony Fu Nov 26, 2011 08:09 AM

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Using baby servos in the ailerons in particular I used an external bearing kit to stop head rock and reduce side load on the wing servos. It really helps to produce a slop free install. The bracing of the servo to both the top and bottom skins is the key though. I don't like servo frames as you can never get rid of skin flex this way. The arms are 10mm for flaps and 5mm for ailerons. This with the factory installed horns and using maximum servo travel gets the throws needed. The pushrods are decent stainless steel in ailerons on threaded L bend (because of small arm) and 303 grade stainless steel in flaps using clevises at both ends. The bearing kit is my own Fu-Fix kit and the housing is tied to both skins with a ply brace. All arms are under the skin so a flat cover can be used. The bubble covers supplied are not necessary. This makes an even cleaner wing.

#9 Tony Fu Nov 26, 2011 08:23 AM

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All the wing plugs are auto-mating. The centre panel is a good old computer D plug (recesses moulded) and tips I used the ubiquitous MPX greens.

Here it is after many cups of tea!

It comes in at 2.2kg rtf. So at 450w that's about 90w per lb in old money!

#10 Tony Fu Nov 26, 2011 11:48 AM

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Here's the money shots: section is markedly undercambered towards the TE and did I say the flaps are huge!! Ailerons too aren't small either (neither is the tail). This is going to make one interesting E glider as wt is nearly same as glider version so should fly very similar and by all accounts that's going to be great!
Incidentally, spar is made in separate moulds and not built in situ as the norm. Far more control in laying up and varying the strength and wt/resin content. Some special technological advances in what is after all a very good priced 3.5m competition soarer.

#11 vasil_m Nov 27, 2011 01:30 AM

E Vulture 3500
Thank you Tony,
I hope this option to appeal to other lovers of this sport!

Vasil Milev

"MVM model" -Bulgaria

#12 Tony Fu Nov 27, 2011 03:21 AM

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Thanks Vasil, you make an outstanding plane and I wish you every success with the Vultures!

Although you fly F3J and the Vulture has been designed for this class I must point out I like your electric conversion fuse very much indeed.
Specifically, what is right about it is as follows:

The radio hatch at the bottom of the fuse under the wing seat is so convenient. The fuse loom from the wing can be made very short and getting to the servos and rx is greatly improved. You have no problems with what ever gear you put in, large or small. It really does solve a lot of installation headaches and structurally it does not compromise strength as a boom cut out would.

The shortened nose is about perfect. Even with the tiny motor used here Hacker A20 geared 6XL I can balance within range, just about. I dare say most will use a heavier and more powerful motor. I know of one in the UK now being kitted out with a Neu 1115 and Kontronik KPG25 for F5J. Balancing will not be an issue.

The nose motor mount moulding is nicely done and saves a lot of hassle as it incorporates a carbon tow inner lip and the inner sides are made into a short tube. This makes location and gluing of the motor mount so easy as further reinforcement other than a thick bead of epoxy is not necessary.

The E fuse is glass kevlar with a few carbon tows down the boom. 2.4 installation is not a problem and allows a number of locations. The nose area is quite twist free and structurally strong already for electric motors, some electric planes are quite poor in this respect and require reinforcement to stop the nose area twisting.

All in, a very well designed electric fuse especially as you can use a great variety of power set ups and not be restricted by space or installation options.

#13 NikolayPeichev Nov 29, 2011 12:45 AM

Hi Tony, could easily put the CG of 94-95 mm. My version F3J model which flew behaves very well in these values ​​of cg. I follow with interest your post and I expect your opinion about the first flight. Good luck and happy landing .

R, Nikolay

#14 davidleitch Nov 29, 2011 01:14 PM

Great build thread. I will be interested in the climb performance for that weight and size of glider and power.

#15 Big Browns Dec 13, 2011 12:46 PM

Have you flown the plane yet? How do you like it? I have a F3J version coming to me very soon. I'm thinking about gettina an electric fuse, but I want to wait to see how everyone is liking it first.


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