RC Groups

RC Groups
    Electric Ducted Fan Jet Talk
        Mini-Review F-86 Sabre "Skyblazers" by Kyosho

#1 Herb Oct 18, 2005 05:16 PM

F-86 Sabre "Skyblazers" by Kyosho
3 Attachment(s)



I received a few questions about my gas to electric conversion of the Kyosho F-86 Sabre,


(specs are listed above).

I found the kit at a LHS (Ultimate) about six months ago - at a very good price, it did not seem to sell very well. I had seen the gas one (OS .15 CV-DF) fly and it flew ok - but boringly slow ... :

Kyosho F-86 Sabre video with OS .15 CV-DF

I heard people had just swapped the 90mm Kyosho icdf fan for a WeMoTec MidiFan, but that option I found unappealing because of the lack of any ducting. So I carefully made my own ducting plug out of blue foam, covered it and glassed it. After reinforcing it with carbon tow, I found it fitted quite well.

The intake area (around 37 cm^2) determined the fan size: I needed to get (from warbirds-rc.com) a WeMotec 620, 85 mm diameter, with an eff. fsa of about 43 cm^2. The Sabre intake is a bit bigger than my K&A MiG-15 (33 cm^2) which flies very well on the smaller HW-609 fan (eff fsa 32.2 cm^2).

In any case the 90mm Midi is just too big to allow space for both ducting and batteries (unless you cool the batteries in the ducting :rolleyes: ).

Here's the finished product, after the maiden (actually two flights), last Saturday Oct. 15 :



#2 Herb Oct 18, 2005 05:21 PM

The setup right now is a WeMotec HW-620 fan (85mm) w/o motor cone & large spinner gap for cooling,


a Hacker B50-18S (three years old, 100+ flights), a Jeti-Hacker Master 77A controller and 6S (3S+3S) Kokam 3200 HD pack. Also a separate receiver battery (350 mAh), three HS-85MG servos and fixed (stock & removable) gear.

It's very cramped inside and the Kokams & ducting just barely fit :eek: .

#3 Chris True Oct 18, 2005 05:23 PM

Looks great Herb! Fixed gear?

#4 Herb Oct 18, 2005 05:27 PM

4 Attachment(s)
I comes with a very nice and light one piece fuselage. And avery nice decal set. The tail is slightly enlarged, which I don't mind as it probably flies better.


#5 Herb Oct 18, 2005 05:32 PM

4 Attachment(s)
It took me a looong time to do the ducting, a lot of patience first doing the plugs and then making the ducts themselves. Straighforward but tedious.

Here's some pictures of the duct work (fiberglass, carbon tow reinforced):


#6 Herb Oct 18, 2005 05:41 PM

5 Attachment(s)
Thanks Chris ! Yes fixed gear, for now.

Mylar tube for exhaust, choked down quite a bit to around 65mm (I think).

Elevator servo was re-positioned out of the way, with silver soldered y-linkage. Receiver is positioned in cockpit, batteries are sitting left (3S) and right (3S) of the duct, resting on the wing.

The cooling intakes, which I had thought initially of removing, are in fact just in the right position to blow air on the Kokams and the ESC.


#7 JetTech Oct 18, 2005 05:46 PM

That looks sharp! Tell us how it flew.........speed? rog? Stuff like that. How much does it weigh ready to fly? Size (in inches please) :D for us that don't do the conversions very well. Oh yes and your mothers maiden name... :rolleyes: Just kidding about that last one. Seems like I am always getting asked that question for some reason or another.


#8 Herb Oct 18, 2005 05:48 PM

3 Attachment(s)
For now I have used the (fixed) landing gear that comes with it, it's simple to install and seems to work. The nose gear is fixed (no steering) and a bit weak - in the original the strut went all the way to the top of the fuse theorugh a ply plate (now removed to save weight).

If I really like a lot the way it flies, I might think about Springairs 602's. The retractable nose gear + steering would be a really tight fit :( ...


#9 Herb Oct 18, 2005 05:59 PM

This is a very lightweight kit (that's the reason I liked it in the first place :) .

Out of the box the empty plane weighs 29.9 oz (850 g) without servos, electronics, motor, fan, cables, batts, esc.

The wings are 4.3 oz (left) and 4.5 oz (right). The fg fuse is 11.5 oz.

My weight ready to fly came out at 69 oz (4.3 lbs, 1960 g) , which means it should fly well on as little as 700+ Watts. In which case a 3S setup might be more appropriate.

The Sabre's power setup on 6S Kokam 3200's HD delivers around 1380 Watts full throttle (cold batteries), which seems enough for a brisk takeoff in less than 80 feet or so.

The Sabre cruises along nicely at 1/2 throttle. Low drag and low weight means a whistling 100mph is erached quickly. The airframe (tail surfaces) seem a bit flimsy so this one's not designed for breaking speed records.

#10 Herb Oct 18, 2005 06:07 PM

The maiden was last Saturday, the wind was blowing at 20+ knots. CG was at 175mm according to (latest) instructions. Throws were as per instructions (5mm ail, 10mm ele).

This is the first plane I have ever built that did not require any trim inputs to fly straight and level hands off on the maiden :eek: !

The CG seems a bit foward (fast landings), the elevator throw was too low (having a hard time pulling the nose up on landing) , the ailerons throws were a bit too much, and were reduced after the first flight.

As I said, it cruises along nicely at 100mph at half throttle or so, it's the quitest and smoothest edf yet, perhaps because the fan mount I made is really strong but the silicone really smooths out the vibrations & resonances.

All in all, a wondeful kit. But a lot of work to make those ducts !!

#11 JetTech Oct 18, 2005 06:37 PM

Thanks for the report Herb. It sounds like a very nice kit. One of the LHS has a bunch of the Kyosho war plane kits in stock. They all look very nice.
This is the size of plane I like best. I am able to keep them oriented better it seems. It will be interesting to see how your retract set up goes. Keep us posted on that also.

#12 Arbo Oct 18, 2005 07:16 PM

Great job Herb. I wondered if anyone was ever going to convert one of these... I know they've been out for a while.

#13 bmiller Oct 18, 2005 09:34 PM

Looks great! Hope to see it fly in person very soon.
I remember you talking about doing this conversion 3 years ago!!!
The advent of LiPo battery technology has really made this type of conversion possible. :cool:

#14 hoser Oct 18, 2005 10:40 PM

glad someone figured that one out, good job Herb

#15 kriptonic Oct 19, 2005 02:26 AM

Really nice Herb, I'm wondering how many people out there would like a set of ducts???


All times are GMT -5. The time now is 11:11 AM.