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Old Apr 25, 2014, 07:27 PM
Skip Miller Models
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United States, CO, Boulder
Joined Dec 2013
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New Product
Kappa 35, NEW RELEASE!!! 45oz RTF!

Skip Miller Models is pleased to announce the newest addition to our quiver of high end competition oriented sailplanes. The KAPPA 3.5m F5J and ALES bird!!!

The blend of building materials (carbon, glass, rohacell) is seamlessly intertwined into what is a strong, yet unbelievably light airframe. The trailing edges are sharp and straight as an arrow, control rods are pre-installed in both the wing and fuse, servo covers pre-cut and ready for installation.

This Electric specific model has not been overbuilt in order to take landings and high stress winch lauches as many of the F3J to F5J conversions we see, instead it has been methodically designed to give every advantage possible in the electric competition circuit. With a RTF weight of only 45oz this model is sure to be an absolute stunner!

Get yours on order today!
http://www.skipmillermodels.com/product_p/kappa.htm
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Old Apr 26, 2014, 12:02 AM
agnotology
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Joined Jan 2007
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Very nice!

It looks quite high aspect ratio. Any specs an AR, wing area, etc.? Proprietary airfoils?

What motor diameter will it accept? With the high AR wing, and maybe thin airfoils (?), what thickness servos are needed for the flaps and ailerons?

There looks to be a lot of carbon in the front of the fuselage. I assume it needs external antennas?

Thanks,

Kevin

Edit: I found some info:

http://translate.google.com/translat...php%3Fpid%3D23

I calculate the AR to be about 20.3, with an average chord of 171mm. It is spec'd at 60 dm^2 wing area, or about 930 in^2. At 45 oz flying weight, the wing loading would be about 7 oz/ft^2.

It states it takes a 38mm spinner, so even 36mm outrunners may fit.
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Old Apr 27, 2014, 09:34 AM
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Joined Aug 2009
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Wow, they are getting even lighter!!
Like BIG DLG's with motors!!

Terry
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Old Apr 27, 2014, 12:49 PM
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Albuq, NMex USA
Joined Jan 2001
609 Posts
Ah! These are the folks that made the Mystic that NSP use to sell. I recently purchased a used one and was looking for an electric fus. Thanks for the link Kevin.

These folks make the highest quality, innovative products. The Mystic was a few years ahead of its time.
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Old Apr 27, 2014, 06:12 PM
agnotology
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Joined Jan 2007
3,678 Posts
It is a very interesting model.

The fuse definitely does not look 2.4GHz friendly.

Some more info here:

http://translate.google.com/translat...age%3Dkappa-35

Kevin
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Old Apr 28, 2014, 03:23 PM
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Albuquerque, NM
Joined Jan 2010
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I'm interested too...a couple of things that I'm still wondering about.....not familiar with those Mega motors, are they geared inrunners? Even if a 35 mm outrunner would fit, the clearance for the motor wiring might not be sufficient.

Also, how much wiring for the wing servos is in place ? I see they are using the little green multi-pin connectors for the wing hook-up. They work but are a pain to wire up and delicate for the long term...
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Old Apr 28, 2014, 03:51 PM
agnotology
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Joined Jan 2007
3,678 Posts
The MEGA 16/25/4E is a direct drive inrunner, 1250KV, 25A max sustained on 3 cells, 115g, only a 3.2mm shaft I think:

http://www.megamotor.cz/v4/script/de...4b69fee1c3c338

Tested up to 35A on 3S and a 12.5/6 folding prop:

http://www.megamotor.cz/v4/script/de...4b69fee1c3c338

For the power required on a 45oz. glider, there are 28mm outrunners that might work too, or the Hyperion 35mm outrunners with the wires further back might fit. Maybe lower KV and a bit bigger prop on the outrunner. Only the expensive inrunner or outrunner and gearbox combos to get down to the 100g area, which are probably overkill on a 45oz glider.

External antennas are required, all CF in the nose.

Kevin
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Old Apr 28, 2014, 04:56 PM
Flying = Falling (Slowly)
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Tulsa, OK
Joined May 2004
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Quote:
Originally Posted by kcaldwel View Post
The MEGA 16/25/4E is a direct drive inrunner, 1250KV, 25A max sustained on 3 cells, 115g, only a 3.2mm shaft I think:

http://www.megamotor.cz/v4/script/de...ge_id=lang_eng

Tested up to 35A on 3S and a 12.5/6 folding prop:

http://www.megamotor.cz/v4/script/de...ge_id=lang_eng

For the power required on a 45oz. glider, there are 28mm outrunners that might work too, or the Hyperion 35mm outrunners with the wires further back might fit. Maybe lower KV and a bit bigger prop on the outrunner. Only the expensive inrunner or outrunner and gearbox combos to get down to the 100g area, which are probably overkill on a 45oz glider.

External antennas are required, all CF in the nose.

Kevin
Its got a fairly long nose and servos mounted up front -- pretty much like one of my Maxa's. I suspect that if you want to get it to balance without adding weight to the tail, that the 100 g motor/gearbox would be useful.

Happy Landings,

Don
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Old Apr 28, 2014, 05:03 PM
agnotology
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They are using the 80g direct drive motors in some of the light F5J gliders now, like the Mega 16/15/5E. No real need for the expense and complexity of high power gear motors for F5J with a light enough airframe:

http://www.f3j.com/perfection_electro.htm

Kevin
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Old Apr 28, 2014, 07:34 PM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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Quote:
Originally Posted by kcaldwel View Post
They are using the 80g direct drive motors in some of the light F5J gliders now, like the Mega 16/15/5E. No real need for the expense and complexity of high power gear motors for F5J with a light enough airframe:

http://www.f3j.com/perfection_electro.htm

Kevin
I suspect that the Mega 16/15/5E is an outlier right now. It is an inrunner and looking at its specs I still wonder if it is hooked up to a gearbox.

The Peggy Pepper is a Scorpion out runner with a Reisenauer gearbox -- a pretty potent unit.

The rest of the recommendations on the Samba site are all inrunners running through gearboxes -- weights from around 110 to 130g.

I am using the Powerline 1025 with a 16x8 prop and a TP 850 3S battery in a 63 ounce Maxa. The motor/gearbox weighs about 100g which is pretty much as light as any of the alternatives. It runs at about 400 watts and will launch the plane to 200 meters in about 24-25 seconds.

The bottom line is that most of these drives -- even for the lightest planes are running about $200+.

The tough thing about all of these planes is being able to accommodate servos in the pod AND no weight in the tail. At least to me it is crazy to spend 2 1/2 grand on a super light-weight composite and then strap a couple of quarters to the tail. But that's just me.

Happy Landings,

Don
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Old Apr 29, 2014, 02:09 PM
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Old Apr 30, 2014, 09:59 PM
agnotology
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Joined Jan 2007
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Quote:
Originally Posted by dharban View Post
I suspect that the Mega 16/15/5E is an outlier right now. It is an inrunner and looking at its specs I still wonder if it is hooked up to a gearbox.
...

The tough thing about all of these planes is being able to accommodate servos in the pod AND no weight in the tail. At least to me it is crazy to spend 2 1/2 grand on a super light-weight composite and then strap a couple of quarters to the tail. But that's just me.

Happy Landings,

Don
Once the flying weight gets down to 1.3kg or so, there are several 28mm diameter direct drive motors in the 80g range that will provide enough power for a lot less $ than the gear motors, and less change needed in the tail as well! 20% lighter and 60% lower cost...

The Mega MEGA 16/15/5CE is used direct drive. The "C" indicates the "Combat" 5mm shaft, I'm not sure what the "E" indicates.

These are the Mega motor recommendations for F5J. They list a gearbox for the motor needing one:
  • Up to 2 Kg : Electric motor MEGA 16/25/4CE 10-11“ , or MEGA 16/7/4E+PG3:1 (11X6 -12X6 )
  • Up to 1,6 Kg : Electric motor MEGA 16/15/5CE (88g), 11x6CAM , current consumption up to 35A ... Motor MEGA 16/15/5 (76g), 10x6CAM , current consumption up to 35A,
  • Up to 1,3 Kg : Electric motor MEGA 16/15/7C , (76g), 11x6“CAM , current consumption up to 25A

The Hyperion [SIZE=2]Gs2218-10 (400W, 84g) would definitely be suitable as well, but unfortunately doesn't seem to be available anymore:

http://media.hyperion.hk/dn/gs/

There are some low cost 28mm motors that would likely also work fine, but I know the very thought will make Don shudder:

http://www.hobbyking.com/hobbyking/s...00KV_530W.html

http://www.himodel.com/electric/EMAX...GT2218_09.html

Kevin
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Old Apr 30, 2014, 10:09 PM
Red Merle ALES
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United States, Mt, Helena
Joined Apr 2002
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Ammo I runner with a Greatplanes Gearbox.
http://www.rcgroups.com/forums/showt...5#post26408701
Approx $100 for both.
Curtis
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Old May 01, 2014, 12:09 AM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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Quote:
Originally Posted by kcaldwel View Post

There are some low cost 28mm motors that would likely also work fine, but I know the very thought will make Don shudder:
Hey Kevin, knock yourself out. I don't give a crap what kind of motors people use or how much they cost. Whatever blows their hair back.

I have tested a wide variety of motors in a variety of planes including outrunners and inrunners, cheap and expensive. I especially liked the Hyperion sailplane outrunners as a matter of fact. They all have their place.

In running the motors I have made the following broad observations:

1. Cheap motors give you what you pay for (and sometimes that's plenty good). But they are almost always made of crummier materials than some more expensive motors. Softer alloys in shafts and cases which bend more easily. More importantly, cheap magnets which not only run a bit hotter, but which succumb to thermal degradation more than better magnets. This CAN BE MATERIAL in applications where you push small motors to their limits.

2. Input wattage is not a particularly good way of comparing motors. A plane with a properly fitted LARGE slow turning prop can perform much better at any particular level of wattage than one with a smaller, faster turning prop. In one set of applications I ran a Neu 1105 with a 4.4:1 gearbox against a Neu 1105 with a 6.7 gearbox -- both at about the same input wattage and both with props pitched to match the plane. There was no comparison in actual performance. The 6.7 plane consistently pulled more than 20 percent faster than the 4.4 plane.

3. I suppose for many applications it doesn't matter all that much. But for minimum weight applications in F5J and especially ALES APPLICATIONS, all of the motors we are talking about will be marginal for everything over light wind flying -- at least with higher winds, necessitating a two plane quiver. My Powerline in a 62 ounce Maxa is not really suited to pulling a ballasted plane to 175 to 200 meters in 15 plus mph. It might be suitable in a 45 ounce plus ballast plane. But I really doubt that a less efficient direct drive setup would work all that well. I am not sure I get the "economy" of powering a $2000 plane with an "economical" motor whose performance necessitates a second plane when the wind comes up. I've got two planes, but it would really love a 55 ounce Maxa that could be loaded up and flown (launched) up to about 20 mph winds.

4. I suspect that the best "economical" compromises will be cheap versions of 22 mm outrunners coupled with cheap gearboxes running at around 500 watts. I saw the Hacker setup like this on a Maxa at Phoenix and it performed very nicely for a minimum weight setup. I am sure that it was running pretty hot and I don't know if a cheap knockoff would hold up. But I am sure that someone stuck on saving a few bucks will find out. At any rate these outrunner/gearbox combinations are starting to catch on for F5J planes (the Hacker, the Peggy Pepper and Palo Lishak's Red Fox).

I am a little skeptical about the prospects for HK stuff showing up in very much serious competition. But, whatever.

Happy Landings,

Don
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Old May 01, 2014, 12:41 AM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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Quote:
Originally Posted by Curtis Suter View Post
Ammo I runner with a Greatplanes Gearbox.
http://www.rcgroups.com/forums/showt...5#post26408701
Approx $100 for both.
Curtis
A good value. Probably heavier than you would want for this application. Maybe with a 24 series motor (still a little heavy) if you could get enough power out of it.

If I am going to spend a couple of grand for an ultralight airframe I am probably more concerned about keeping it light in the ends than I am with its overall weight.

My second Maxa has servos in the tail and weighs about 10 ounces more than the light one. Even for me, it is surprising how much better the lighter plane THAT IS LIGHTER IN THE ENDS flies.

Anyway, the Ammo units might be worth looking at.

Happy Landings,

Don
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