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Old Nov 01, 2005, 05:43 AM
Registered User
New Zealand
Joined Sep 2004
13 Posts
Aerotowing with 1/4 Scale Sig Cub

I have managed to aquire a secondhand 1/4 scale cub. It has a wingspan of 106".

I know that an AXI 5320/28 will provide ample power to fly the Cub but how much additional power is required for aerotowing. I am intending on towing up to 160" (4 metre) gliders with it.

My calculations give me a flying weight of 14 pounds for the Cub and a maximum of 1500 watts for 107 watts/pound.

Is this enough for aerotowing safely or is it on the marginal side. Is there a rule of thumb for watts/pound that is used for aerotowing?

thanks in advance
Mike
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Old Nov 01, 2005, 12:33 PM
Supersonic Engineering
GordonTarling's Avatar
UK, Greater London, Uxbridge
Joined Mar 2001
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Advice I have so far received on the subject appears to be to add the weight of the tug and glider and use that weight for a power loading. So, if you had the 14 pound tug and were towing a 10 pound glider, your 1500 watts equates to 62.5 watts per pound, which I'd think would be a bit marginal.
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Old Nov 02, 2005, 05:20 AM
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Surrey, UK
Joined Aug 2003
132 Posts
Electric Tug

A agree - it will be very marginal. A very similar tug in our local aerotow circuit is equiped with a an 80cc petrol engine. That said, another of our regular tug pilots has electrified the 110 inch SIG Rascal which is very impressive and tows 4m and larger gliders with ease. I dont have details of the setup used, but he goes by the user_name of "Rascal" on our Web Forum at www.scalesoaring.co.uk..

Regards
Allan
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Old Nov 02, 2005, 04:25 PM
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GordonTarling's Avatar
UK, Greater London, Uxbridge
Joined Mar 2001
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Don't even TRY to compare the pulling power of a petrol engine with electrics - it doesn't work! Some of those tugs which have ridiculously over-sized (to me) engines in them can be flown just as well with an electric system which, though it can't be called 'modest', certainly couldn't be called 'outrageous' ! A properly chosen electric system has fantastic pulling power - just witness that Rascal - I saw it flying earlier this year and was rather amazed to see how easily it could tow up some really quite large gliders.
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Old Nov 02, 2005, 04:43 PM
MTT
I care about rising air !
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West Chester, Ohio
Joined Feb 2002
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I have read somewhere that the combined power loading should be 100W/kg, or more.
So the above mentioned 62W/lb are not so bad, 100W/kg being equal to 45W/lb.

A fellow club member here in Cincinnati has an electric powered Rascal 110. It is equipped with a big AXI outrunner motor, but I don't recall number & type of cells, and what size prop he uses, but it pulls up my 11lb Flair Ka8 just fine.
None of these spectacular 45 deg + tows, but gets the job done.

Michael
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Old Nov 02, 2005, 05:09 PM
Where's the lift?
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United States, WA, Snohomish
Joined Mar 2001
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Dave Beardsley and I did this very thing: 1/4 scale Sig Cub, Aveox 1817/3Y motor with a 3:1 gearbox and a 20x10 prop, on 32 cells. Don't know off hand what the current draw was with that set-up, so I can't calc the watts per pound, but the Cub did a fine job of towing up my 1/4 scale Flair Ka8b (9.5lb, 3.75m span).

http://www.beardsleys.net/dave/rcmod...ic/cub/cub.htm

Don.
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Old Nov 03, 2005, 06:53 AM
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New York
Joined Feb 2002
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Looks like we've got the makings of an interesting experiment. I'm finishing up a big Rascal with a ZDZ 40RV up front. Hope to get a little towing in before winter. Will let you know what the gas version can do, then we can compare to electrics.

I saw electric Rascals towing up 5+ meter sailplanes with ease this summer, quite impressive, as was the lipo fire that destroyed one of them!

Regards,

Steve
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Old Nov 03, 2005, 09:27 AM
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USA, NY, Chestnut Ridge
Joined Jun 2000
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Take a look at my 1/4 scale Super Cub towplane.

http://www.rcgroups.com/forums/showthread.php?t=257227
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Old Nov 06, 2005, 12:57 PM
Registered User
Hinwil, Switzerland
Joined Oct 2005
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Aero towing with SIG 1/4 Scale Super Cub

Hi there
I'm an aero modeller from Switzerland, being very interested what's going on
in the USA and having some nice contacts.
Actually I'm doing some aero towing with both 1/4 scale SIG Cubs, the regular
and the clibbed wing. Up front there is working a Flyware e-motor made in Germany. A Hacker Jeti Master 77 opto flight ESC is doing fine. Equipped with
8x4 8000mAh ThunderPower batteries turns a 20x8 prop about 6200 rpm's
With an full loaded pack I pull about 6-10 gliders with a weight starting at 2,5 kg up to about 10 kg to an altitude of ca. 400m.
This way I pull about 30 Amps.
Hope I could help you outthere on taking decision to set-up an electrified towing plane
Regards
Martin Steiner Stemasoft
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Old Nov 06, 2005, 06:24 PM
modest-master's Avatar
Palm Bay, FL, USA
Joined May 2001
1,236 Posts
No problem can be very easily done.
I am flying Dave Patrick Piper PA-18 with clipped wings and towing 4.8m DG-600 hollow molded glidr
Whole conversion was very simple.

This is my set-up:
AXI 5330/24, Jeti 90 ESC, TP8000 10S4P battery and 22x12 propeller
I get up to 8-9 tows per one charge.

www.EspritModel.com
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Old Nov 10, 2005, 04:14 PM
Registered IGG Finland pilot
Hannu Vuorinen's Avatar
Finland IGG-FIN
Joined Feb 2003
682 Posts
Hi,

Below link to some videoclips of my 1/4 electric - Cub aerotowing,
its equipped with Actro 40-6, 42A / 1350watts.

http://www.kolumbus.fi/sxh/video.html

It use to be many times our primary tug for 1/4 scale gliders,
like 4 meter K-8 . Ofcourse it is not capable of 30 deg insane looking
pulls like big gassers, but nice and smooth scale-like tows.

BR,
Hannu
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Old Nov 10, 2005, 04:28 PM
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Finland IGG-FIN
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And the other one is very similar to Martin´s one, Flyware T-Rex,
and 9s Kokam 8000mAh pack, in 89" semiscale Agwagon.
Hacker -77 esc a bit modified for better cooling..
No problem at all to pull 4 meter Twin Astir etc.

Br,
Hannu
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Old Nov 10, 2005, 10:23 PM
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New Zealand
Joined Sep 2004
13 Posts
Thanks for all the info guys. I think I will allow for a motor capable of 2000 watts continuous.

The Cylcon 160 (very light for its power rating) or an AXI 5330/16 both seem to fit the bill. Are there any other I have missed?
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Old Nov 15, 2005, 04:12 PM
Registered IGG Finland pilot
Hannu Vuorinen's Avatar
Finland IGG-FIN
Joined Feb 2003
682 Posts
Quote:
Originally Posted by M. Clarkson
Thanks for all the info guys. I think I will allow for a motor capable of 2000 watts continuous.

The Cylcon 160 (very light for its power rating) or an AXI 5330/16 both seem to fit the bill. Are there any other I have missed?
Hi,

Unless, if you dont want a bit bigger..
Onboard aerotow-video of 2,7KW powered, 14ft E-tug towing 17ft Ka-6:
http://www.printechobby.fi/kauppa/ga...kahinaus2.mpeg
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Old Nov 15, 2005, 05:54 PM
Registered User
Belle Mead NJ
Joined Mar 2005
71 Posts
Wow...Nice plane !!!
Maybe next year the pilot will be at the right scale

Fab
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