Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Jan 10, 2013, 12:03 PM
Registered User
Pittsburgh, PA
Joined May 2008
1,022 Posts
Help!
Need some guidance on e-powering one of my floaters

I'm trying to add a motor to my old 3m gas bag but don't have a lot of room to play with in the nose. It looks like a 28mm outrunner will be about the max and still fit inside once I chop the nose. Also it looks like the servos will have to be moved back toward the bulkhead which is no issue. My question is will a 200W outrunner with an 11X6 folder work decent enough? Also it looks like battery room will be very limited. I have some 800mah 3cell batts but would that be sufficient or should I figure out a way to cram in my 1500mah lipo? Thanks for the input in advance
jwhitacre is offline Find More Posts by jwhitacre
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 10, 2013, 01:04 PM
WINS - Winch In Nose Sailplane
jaizon's Avatar
USA, NH
Joined Mar 2008
3,092 Posts
What is the weight of the model and what are your plans for it? (ALES? just sport flying?)
jaizon is offline Find More Posts by jaizon
Reply With Quote
Old Jan 10, 2013, 02:15 PM
Registered User
Joined Apr 2012
2,509 Posts
That's a whole lot of glider for a 28mm motor and 200watts would be marginal at the very best. Your best bet would probably be a geared inrunner but then you might have to lengthen the nose to make everything fit. Another option would be to bulge the nose for a 35mm motor. One of the most powerful 28mm outrunner motors for a low price is the HobbyKing 2834. I have one on a 3D plane, plus two I just ordered yesterday, and I'm swinging a 11" slo-fly prop and pulling 375watts with a 11.1volt battery.

https://www.hobbyking.com/hobbyking/...dproduct=17600
peterlngh is online now Find More Posts by peterlngh
Reply With Quote
Old Jan 10, 2013, 02:31 PM
Registered User
craigrrr's Avatar
San Diego area
Joined Jul 2006
526 Posts
Another option is to consider mounting the motor in front of the firewall.

It is often possible to make it pretty by placing a removeable balsa cowl around the motor (if the motor can is a small enough diameter).

You probably will have to reverse the shaft of the motor for this mounting.

As for motor size you might need something bigger. My 3 meter plane only weighs 40 oz and my motor generates 250 watts.

Craig
craigrrr is offline Find More Posts by craigrrr
Reply With Quote
Old Jan 10, 2013, 02:48 PM
Registered User
Pittsburgh, PA
Joined May 2008
1,022 Posts
Weight in it's current form is 40oz RTF. I'm just looking to get it up to 200-300ft in a reasonable climb. Need a lazy day sailplane for when I don't want to drag out the high start
jwhitacre is offline Find More Posts by jwhitacre
Reply With Quote
Old Jan 10, 2013, 02:59 PM
Registered User
Joined Apr 2012
2,509 Posts
Hmmmm. At 40oz. I think it's doable with a 28mm motor. My 2834 generates over 4 pounds calculated thrust. I like power so I would go with something in the 300watt, 30amp, range. You might want to go with a lower kv, 900-1000?, in order to be able to swing a bigger prop.
peterlngh is online now Find More Posts by peterlngh
Reply With Quote
Old Jan 10, 2013, 07:30 PM
WINS - Winch In Nose Sailplane
jaizon's Avatar
USA, NH
Joined Mar 2008
3,092 Posts
250 to 300 watts should be plenty.

you can figure out battery/speed control/prop/motor combinations here:
http://www.ecalc.ch/motorcalc_e.htm?castle
Very helpful.
jaizon is offline Find More Posts by jaizon
Reply With Quote
Old Jan 10, 2013, 09:48 PM
Registered User
Pittsburgh, PA
Joined May 2008
1,022 Posts
Thanks for the help guys. After playing with that calculator I think an elfite park 480 will be the ticket. A 35mm can I know but it seems like it will be better in the long run according to the calculator. I'm going to do some major surgery on the nose and put some 1/16" ply in there once I thin out the balsa walls.
jwhitacre is offline Find More Posts by jwhitacre
Reply With Quote
Old Jan 26, 2013, 11:25 AM
aku
Jeff Cheechov
aku's Avatar
United States, CA, Tustin
Joined Mar 2006
292 Posts
Notes...

Hi jwhitacre.
Just a little more info... I think you will be happier witha 35mm motor and larger pack than 800 mah. Keep in mind that you will need some weight in nose, so why not make it functional? This 2m project has been fun, but I still have some nose weight, and I'm using most of the 1000 mah pack on longer flights. Here's a link
http://www.rcgroups.com/forums/member.php?u=90147

I suggest a test assembly of the system on the glider before you finalize the motor or location. Check the CG and adjust from there. Have fun! Jeff
aku is offline Find More Posts by aku
RCG Plus Member
Latest blog entry: Stobel V2 DLG
Reply With Quote
Old Jan 27, 2013, 06:27 PM
Registered User
Joined Aug 2010
359 Posts
what watt?

Ok I have tried motocalc this program (e-calc)and others and they always say "unrealistic set up, prop will stall or maybe flying speed = 250 Mph " none of which will make me happy. Is there not a program that will let me enter flying weight, model type (3D, sailplane etc) wing area Desired motor run time at full throttle and desired watts per pound and bang it will suggest a battery size including volts and charge rate and a motor in KV plus suggest prop size and pitch.

Seems to me these programs require you buy the motor first then check it out to see if it will work. Being retired I need the program that does what I mentioned.
tlar633 is offline Find More Posts by tlar633
Last edited by tlar633; Jan 27, 2013 at 06:28 PM. Reason: grammer
Reply With Quote
Old Jan 27, 2013, 08:23 PM
MrE
Registered User
United States, WA, Gig Harbor
Joined Aug 2007
2,163 Posts
I just finished an E-Bubble Dancer that came out at 43 ounces all up. Its powered by a Hacker 28mm A20-22L with an 11x6 prop. A quality 800 mahr pack would do just fine. peak watts is only about 220 or so.

That setup will get the 43 oz BD to ALES launch height - 200 meters or 652 ft - in almost exactly 30 seconds, so a lazy launch to 200-300 feet will be a breeze.

No need for a larger, heavier setup. Why have permanent ballast you cant remove on light days?
MrE is offline Find More Posts by MrE
Reply With Quote
Old Jan 27, 2013, 09:53 PM
aku
Jeff Cheechov
aku's Avatar
United States, CA, Tustin
Joined Mar 2006
292 Posts
E-Bubble Dancer

MrE, thats a very nice e-conversion! The Bubble Dancer is a very clean low drag airframe as well. Do you need much nose weight to make CG? Im familiar with the Hacker A20-22, is a very efficient motor. Ive not used one in a glider conversion though. Not intending this to be a thread jack...
Jeff
aku is offline Find More Posts by aku
RCG Plus Member
Latest blog entry: Stobel V2 DLG
Reply With Quote
Old Jan 27, 2013, 10:46 PM
MrE
Registered User
United States, WA, Gig Harbor
Joined Aug 2007
2,163 Posts
I didnt have to add any extra nose weight. In fact, I had to move things around to get the CG back far enough with the 1500 mahr pack Im using now. Thats my only decent small pack at the moment.

Im planning to use an 850 TP 65C pack down the road with a slightly larger hacker A20-12XL. I want a tad more power for ALES contests on windy days and the 12XL will give me an extra 75 watts or so easily for a slight weight gain - offset by the smaller pack. I like to get to altitude in ALES contests with about 5 seconds to spare or so.
MrE is offline Find More Posts by MrE
Reply With Quote
Old Jan 29, 2013, 11:17 AM
aku
Jeff Cheechov
aku's Avatar
United States, CA, Tustin
Joined Mar 2006
292 Posts
Thx

Thanks for the reply.
Jeff
aku is offline Find More Posts by aku
RCG Plus Member
Latest blog entry: Stobel V2 DLG
Reply With Quote
Old Feb 04, 2013, 11:36 AM
Registered User
Pittsburgh, PA
Joined May 2008
1,022 Posts
Thanks for all the info guys. I ended up piking up a Rimfire 35-30-950 outrunner for cheap. I put smaller HS-81s in there to save weight and to free up room. With the new layout I can stuff a 1500mah lipo in it so that should work out fine. Once the LHS gets my 11X6 folder in Thursday I can try the setup out.
jwhitacre is offline Find More Posts by jwhitacre
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! Need Some Guidance With an Old Plane dedStik Batteries and Chargers 2 Aug 20, 2012 12:43 PM
Discussion Need some motor guru help powering my Y6 Bolt Multirotor daign Power Systems 13 Aug 06, 2012 07:12 PM
Discussion Some guidance on Error Code 113 Eoghan FMA Direct 2 Aug 02, 2012 12:51 PM
Discussion Need some help with my power system copperbricks Power Systems 1 Mar 03, 2012 10:20 AM
Discussion Need some guidance upgrading for more power.... Skidood Electric Plane Talk 6 Aug 17, 2007 09:43 AM