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Old Oct 26, 2003, 03:52 PM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,512 Posts
Westfield F-86 Sabre funfighter e-conversion

Westfield F-86 Sabre funfighter e-conversion

After a couple of trips to the field without a flight today I finally maidened my electric conversion of another fun fighter. This model was first flown five or six years ago and was quite nippy on an OS.25FP. The kit was produced by Westfield Model Co and used a more or less flat plate wing section and all balsa built up structure. The range included a Sabre, BAE Hawk, Vampire and Mig 29. The Sabre is 44Ē span, with 308 sq inches of wing and weighs in at around 3.5lbs dry. For the e-conversion I ran the numbers on a similar power train to that which Iíd used in the Cambrian fun fighter conversions, namely an AXI 2820/10, Model Motors 4012-3 controller, 10xCP1700 cells and a 11x7 APC ďeĒ prop. The numbers made sense so I thought Iíd give it a try.

Here is the model in itís first incarnation with an OS .25FP. with a bit of a lump of a cylinder head sticking out of the front and spoiling that lovely Sabre nose.
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Old Oct 26, 2003, 03:53 PM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,512 Posts
This is what she looks like after the e-conversion
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Old Oct 26, 2003, 03:55 PM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,512 Posts
The AXI 2820/10 is fitted to an Ernie Thorpe Moorcraft squirrel cage mounting and bolted to the fire wall. Prior to fitting the AXI I cut off the nose section, with itís big hole for the cylinder head of the 2 stroke, filled the hole with block balsa and carved and sanded the nose to a better looking representation of the Sabreís distinctive hook nose. This balsa plug was then inserted into a plastic pop bottle and using a heat gun a cowl was formed. The plastic cowl was quite floppy so a layer of 0.6oz glasscloth, 30 min epoxy and microballons applied internally gave a nice rigid and relatively lightweight cowl.
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Old Oct 26, 2003, 03:57 PM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,512 Posts
The inside of the Sabreís fuselage is cavernous and you could fit fifty cells in there if need be. However in order to balance for the centre of gravity this required the battery pack to be located right at the back of the open fuselage bay above the wing and a balsa platform was mounted on two rails, a section cut out of the rear former to allow the battery to slide part way through that former and velcro seatbelts similar to those used on my Zagi and Pico Cub installed. The battery is inserted from the front, pushed back through the rear former and the seatbelts pulled tightly around the pack to stop any movement.
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Old Oct 26, 2003, 03:58 PM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,512 Posts
With the battery in and locked by the velcro seatbelts there is still enough room inside that fuselage for flask and butties! The speed controller is velcroed to the roof of what was the fuel tank bay. The holes in the formers give a solid airflow right through the model, exiting along with the radio aerial through a 15mm diameter hole in the position of the jetpipe on the real thing.
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Old Oct 26, 2003, 03:59 PM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
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The battery and all the radio gear are located behind the C of G. I switched from the full size receiver and servos with a 500mah receiver pack that was used on the original IC model to use a HS-85MG mini servo on the elevator, via a forked pianowire elevator pushrod and a Hitec 555 receiver. That meant I was able to remove an ounce of lead from the tail of the model and the net weight of this conversion actually ended up lighter than the IC version.
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Old Oct 26, 2003, 04:00 PM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
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A previous attempt at a maiden flight was thwarted by a mysterious loss of power immediately after the handlaunch, causing the model to hit the deck and skip into the long grass, requiring some minor repairs. Todayís maiden went much better and the model climbed away from a hefty Kev Mullarkey chuck and flew like it was on rails. Flight characteristics are similar to how the model flew on a .25 but the top speed is a bit less. One characteristic that the Sabre had as an IC model was that if you pulled a loop too tightly, she would screw out at the top of the loop.

The model is a comfortable flyer at 3lb 5oz AUW with 10xCP1700s, big loops being easily flown, the roll rate was deliberately sedate for a maiden flight but Iíll turn that up a few notches now that I know the model works and Iím quite pleased with the overall performance. Iíll need to work on those Derry turns now. The Sabre is quite a slippy little model to land and I used every inch of our 100m grass field to put her down to a dead stop.

A clubmate has the same model with a .28cu in 2 stroke up front which is blisteringly fast, though several ounces heavier. Weíre going to try some formation flying of the two Sabres together at some stage in the future to give a direct comparison.
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Old Oct 27, 2003, 02:49 AM
Single-task at best...
tim hooper's Avatar
Telford, UK
Joined Feb 2000
7,488 Posts
.....and about time too!!!

Congrats on the eventual maiden Bri! I know it's been a bit of an uphill struggle with this one, but it was worth it in the end.

I look forward to seeing it fly on our next exchange visit.

tim
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Old Oct 27, 2003, 03:42 AM
Master
ChrisP's Avatar
Weilbach, Germany
Joined May 2001
2,467 Posts
Very nice indeed, Brian.

I'm quite amazed that it can be apparently hand launched fairly easily. I baulk at anything over 20 ozs/sq ft and the F 86 is at 25. Kev must be a retired javelin thrower or something !

My goodness, haven't we progressed light years from the MFA Humming Bird and its 540 motor which was at the cutting edge of British electric aeromodelling in the 80's.

John Derry would indeed be gobsmacked.
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Old Oct 27, 2003, 04:35 AM
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vintage1's Avatar
East Anglia, UK
Joined Sep 2002
29,688 Posts
Its a shame that speed props aren't more readily available. Looks like something like a 9x9 would get more speed than a 10x7.
11x10 looks good, if a little over the top for the motor.

Oh, APC do a 10x10E.

That should be right on the button!

Almost identical draw to the 11x7, but significantly faster.
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Old Oct 27, 2003, 04:46 AM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
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Guys

My shaking knees at the end of the maiden told me that the top speed was just about right for me .

I've watched the Sabre with a .28cu in fitted and it is seriously quick, far faster than I'd be comfortable with. I may do some experimenting with other props over the next few flying sessions. I'm looking more at the capability to sustain huge Sabre-like loops rather than straight line speed.

Thanks Tim - your place or mine?

Chris - all of the funfighter conversions are in the high 20's in terms of wingloading. Kev's handlaunching skills are legendary around these parts (and now internationally) and he is in almost constant demand at whichever flying site he is at for those spearchucks. I can't launch my own models for toffee and greatly appreciate my mate's efforts in that direction- cheers Kev!

Brian
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Old Feb 16, 2004, 11:14 AM
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Steve_Bennington's Avatar
King's Lynn,Norfolk, England
Joined Sep 2001
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One of the Westfield Sabre's stablemates, the BAE HAWK is in RCM&E this month as a free plan!!.


I'm tempted to build it for electric!

Regards,

Steve
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Old Feb 16, 2004, 07:50 PM
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Sabrejock's Avatar
Winnipeg, MB Canada
Joined Jan 2000
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Would this be a candidate for a front motor, rear prop? I've read someplace that with proper prop balancing the long shaft doesn't even have to be supported that well.

Does any North American house handle Westfield kits? Tex.
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Old Feb 16, 2004, 08:36 PM
Faster Faster!!
RCFlybry's Avatar
Kaysville Utah, U.S.A
Joined Oct 2001
1,717 Posts
It sure makes a big difference without that big ugly cylinder head and muffler sticking out of the side doesn't it?
Nice job Brian! This is one of the reasons I ditched glow power and went to e flight.
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Old Feb 17, 2004, 02:46 AM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,512 Posts
Thanks RCFlyBry, it is nice to lose that big lump up front.

Tex I would think one of the significant problems with a front mounted motor and shaft drive to a rear mounted prop would be the swept back tail surfaces and distinctive scalloped tail pipe configuration. That would mean that the extension shaft would need to terminate at least two inches from the back of the fuselage for a 10" prop. I did wonder (for about 30 seconds only) whether you could build one of these as an EDF and then contented myself that the prop won't be very visible in the air.

I'm not sure that the kits are still around, it's been a good while since I've seen them. However IIRC the plan of a very similar model was given away as a free plan not too long ago. The designer Tony Nijuis is an occasional reader of this forum and posts as westfieldmc, so if you are tryng to track down a kit of the Sabre then Tony would certainly be worth talking to as he would have all the gen on that.

Brian
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