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-   -   2 Meter Glider Conversion to Electric - Sample Package (http://www.Wattflyer.com/forums/showthread.php?t=73256)

AEAJR 02-27-2014 02:50 PM

2 Meter Glider Conversion to Electric - Sample Package
 
CONVERTING A PURE GLIDER TO ELECTRIC LAUNCH


I often see questions about converting a pure glider to electric launch. Often it is an older 2 to 3M woody that has been neglected because the pilots no longer wants to bother with a hi-start or a winch. So I thought I would draft something as a starting point for pilots looking for advice on such a conversion.

Have you done a conversion like this? We would love to hear your feedback and for you to add your set-up for other people. Please also add any tips or advice.

What glider did you convert?
What did you use?
What would you do differently if you did it over?


Here are some sample components that would work in many cases. These are certainly not your only options and these are not necessarily the best options for your individual glider, but they give you a feeling for what is needed and you can branch out from here. How much power you need will depend on the weight of the glider, after the conversion, and what kind of climb you want to achieve. My power to weight ratio recommendation would be to shoot for 75 watts/pound for about a 45 degree climb for sport flying. For electric contest flying, like ALES or F5J, I would suggest about 130 watts per pound to hit 200 meters in 30 seconds or less. More than that and you are building a helicopter, but some people feel that way too much power is just about right. ;)


This particular combination of components was based on the conversion of a Spectra 2M to brushless power. The Spectra was built for electric power but used an old heavy brushed motor. This set-up will run about 250 to 300 watts and the estimated finished weight of that glider was about 3 pounds, 48 ounces. Depending on what prop was chosen this would provide a power to weight ratio of about 80 to 100 watts per pound.


I have limited experience with HK motors but many people like them so I have used one as an example here. If you prefer some other brand you can use the specs of these components to help you find the parts you want from another maker.

Most pure gliders have fairly thin noses with tight interior space, so I have selected a 2836 mm outrunner motor with the assumption you are going to put the motor inside. The outside of the motor itself is 28 mm and the length of the internal motor is 36 mm thought the overall motor is actually longer than that. You can see the actual dimensions on the page at the link for the motor. Remember that you need to leave space for the spinning can and have to safely route the wires.


You don’t have to put the motor inside fuselage. Some pilots just cut off the nose block and mount the motor on the outside, later adding a cowl over it. If you do that then you are less constrained in motor size, but again a 28 MM wide motor will work well in most situations. Also having the motor further forward can work well for balance in SOME gliders.

If you are converting an old electric glider, like a spectra, that was based on a brushed motor, be sure to take into account that the brushless motor may be lighter than the old motor. For example a Speed 700 motor is almost 8 ounces while the 2836 motor suggested below is about 5.5 ounces. That means that you will have to add lead to the nose or reposition components forward in order to get the glider to balance properly. Take that into account. An electric conversion can often be an opportunity to move things around to achieve the best weight distribution possible and avoid adding a lot of lead.

I am using a 2836 motor as the example. Max power is 330 watts. However the actual power level will be based on what prop you use. I would guestimate about 250 to 300 with one of the props I recommend. So this could be a good fit or a 30 ounce glider at 130 watts per pound for ALES contests or a 48 ounce glider at 75 watts per pound for casual sport soaring.

HobbyKing doesn't provide a prop recommendation for this 28X36 motor but, from the posts by users, a 10X6 or 10X7 should do. Maybe an 11X6. Be sure to test with a watt meter.
http://www.hobbyking.com/hobbyking/store/__18158__Turnigy_Aerodrive_SK3_2836_1040kv_Brushle ss_Outrunner_Motor.html


If you have a lighter glider you can consider a 2830 for lighter weight at a lower amp draw, about 180 watts. This would work for a 20 to 36 ounce glider depending on the power to weight ratio you want. Be sure to use a proper prop size, probably a 9X6, and a proper ESC, around 20 amps. Always look for a manufacturer’s recommendation and look at recommendations by users. Always check it with a watt meter.
http://www.hobbyking.com/hobbyking/store/__32004__Turnigy_Aerodrive_SK3_2830_1130kv_Brushle ss_Outrunner_Motor_USA_Warehouse_.html


ESC – For the 2836 motor this needs to be at least 30 amps. Whatever ESC you use, confirm it has a brake before you buy or the prop will keep spinning and KILL the glide. Most ESC don’t need any kind of special programming card but some do offer them and they can make set-up simpler. I have my gliders set to brake on. If I have an option I set for a soft start and a soft brake to reduce the load on the motor. For gliders those settings are usually fine.
http://www.hobbyking.com/hobbyking/store/__2164__TURNIGY_Plush_30amp_Speed_Controller.html

Not sure if this spinner will be wide enough for the folded blades to clear the fuse of your glider with an internal motor mount. This is just a sample that would work with the 2836 motor. If you are mounting the motor externally than it is less of an issue as you will design the cowl to match to the spinner.
http://www.hobbyking.com/hobbyking/store/__17890__35mm_Carbon_Fiber_Spinners_for_Folding_Pr opeller_3_17mm_Shaft_.html


These blades are where I would start with for the 2836 Motor. I would get a 10X6, 10X7 and maybe an 11X6 to test. They are cheap enough. Here is where a wattmeter comes in very handy to insure you know what power draw you are creating with each prop so you don't under or over load the motor.
http://www.hobbyking.com/hobbyking/s...op_Blades.htmlhttp://www.hobbyking.com/hobbyking/store/__18068__Carbon_Fibre_10x6_Folding_Prop_Blades.htm l

I would recommend a 3S lipo for the 2836 motor in the 1800 to 2200 mah 20C+ range for fit and weight. Figure 20 to 40 second climbs at about 25 amps. Expect about 3-4 minutes full throttle run time from the 1800. That should give you about 4-6 good climbs with some reserve.

Something like this will probably work. Measure the space for the battery. And be prepared to solder connectors to match the battery and the ESC.
http://www.hobbyking.com/hobbyking/store/__9274__Turnigy_1800mAh_3S_20C_Lipo_Pack.html


Feel free to ask questions. If this all seems confusing because you don't understand electric power systems you might find this book useful. Read the above, then look at the chapters of the book, then read the above again and it will start to make sense.

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
http://www.wattflyer.com/forums/showthread.php?t=31071
http://www.rcuniverse.com/forum/m_7100376/tm.htm

fhhuber 02-27-2014 06:50 PM

I'm in the middle of building/converting a Gentle Lady right now.

Dynam "22" motor (because I have it. Forgot the kv, but its a bit low)
Castle Thunderbird 35 (because I have it)
This combo swinging an APC 10X4.7 E has been tested to run 17 min full throttle on 1800 mah 3S. (was on a 36 inch Tiger Moth and was more than enough)

I still need to select a folding prop. There is no good equiv to the SF prop I have used on this motor before.

I expect final RTF weight to still be below box list for pure sailplane due to using 9 gram servos and the Lady's tendency to need 1 to 2 oz lead in the nose anyway. Instead of that "dead lead" I have a motor up front.

AEAJR 02-27-2014 08:10 PM

did you post a conversion thread? If so, please post the link so people can learn from our work.

rreid7 02-27-2014 08:31 PM

I also recently electrified a Gentle Lady, one that I originally built as a pure glider over 25 years ago, so it was also a restoration project. I used a PowerUP 400 Sport motor from Heads Up RC, a 20A ESC, 8x4 GWS prop, and 3S 1000 mAh Lipo. I haven't bothered with a folding prop so far. Climb outs are probably at least 45 degrees, maybe more. It takes a whole lot longer to come back down, even when there's no lift about!

More details and pictures can be found at my website, if interested:
http://www.rcfliteline.com/on-the-fl...-motor-glider/

AEAJR 02-27-2014 09:54 PM

Did you ever put a cowl over the motor?

carpetbagger 02-28-2014 12:00 AM

In the works - MG 049 (outerzone plan) 69" span which the designer flew on a Cox .049 Black Widow at AUW of 1 kg. Cox BW = 60 watts. Model is framed up and it appears it will be much lighter than 1 kg. Haven't picked a motor yet. Soon as the completed plane is on the scale I'll select a motor from my gear box.

rreid7 02-28-2014 01:26 AM

No motor cowl yet, but I've been watching for something that might serve the purpose. The clear plastic top of the box a Hitec HS-65HB servo comes in almost worked, but was just a touch too small. Of course I could fabricate or carve something, but it really doesn't bother me too much as is.

AEAJR 02-28-2014 03:31 AM

The top of a small plastic shampoo bottle or something like that might work. Use a heat gun to shape it to the nose of the glider.

fhhuber 02-28-2014 08:30 AM

Carve a balsa plug... stretch a common soda bottle over it and apply heat. The bottle will shrink around the plug.

carpetbagger 02-28-2014 11:51 AM

Quote:

Originally Posted by fhhuber (Post 941157)
Carve a balsa plug... stretch a common soda bottle over it and apply heat. The bottle will shrink around the plug.

I carve a balsa plug and mount it on a stick, clamp it upright in a bench vise, then inflate a balloon and press it over the waxed plug while letting the air bleed off. Wax again, and drape a few layers of 1 1/2 oz fiberglass over it, mix up WEST resin, soak FG cloth, inflate another balloon and repeat the press over while bleeding air off again. Keep a zip tie or two handy to cinch balloon around the stick since resin is slippery and balloon may want to slide back off. Go play with other model projects until resin kicks and cures, remove FG from plug, trim to fit, paint. One light weight cowl ready for action . . .

rreid7 02-28-2014 12:12 PM

"top of a small shampoo bottle or something like that."

Yeah, something like that. The world is full of cowlings disguised as something else.

"Carve a balsa plug... stretch a common soda bottle over it and apply heat. The bottle will shrink around the plug."

That's a good one too, I've done that several times. Thanks for the suggestions!

fhhuber 02-28-2014 02:13 PM

PET bottle material will absorb impacts that would shatter the same weight fiberglass and never crack.

A little harder to keep paint on the PET material though...

Essentially the same plug is needed for the PET soda bottle cowl as for the fiberglass one. But its less than 5 min a cowl for the PET vs hour(s) for the fiberglass ones and the cleanup for the PET is to toss the scraps of bottle you cut off.
Its hard to spill any liquid when you aren't using any.

Best is finding a bottle the right shape already.. but that is sometimes very hard.

AEAJR 02-28-2014 03:08 PM

In many cases I imagine you could use the nose block you cut off as the start of plug, perhaps with a few minor mods.

carpetbagger 02-28-2014 03:20 PM

Quote:

Originally Posted by fhhuber (Post 941171)
PET bottle material will absorb impacts that would shatter the same weight fiberglass and never crack.

A little harder to keep paint on the PET material though...

Essentially the same plug is needed for the PET soda bottle cowl as for the fiberglass one. But its less than 5 min a cowl for the PET vs hour(s) for the fiberglass ones and the cleanup for the PET is to toss the scraps of bottle you cut off.
Its hard to spill any liquid when you aren't using any.

Best is finding a bottle the right shape already.. but that is sometimes very hard.

Yeah, all true, but I like playing with FG & resin. I use 1 1/2 oz cloth, WEST resin, and peel ply to do center of wing beef up. Squeegeeing peelo ply over the wet cloth results in a very smooth job with no sanding/filling required. Also saves a few grams as the excess resin squishes out thru the peel ply.

But I do have a industrial grade heat gun - 750 deg at WOT methinks, so I no doubt will try molding plastic.

John Wells 11-21-2015 05:06 AM

I have a Spirit 100 with flaps and ailerons that I'd like to convert to electric. It's been high started all of it's life. I'm looking for a list including the bec, motor, folding prop and batteries that I should get. I don't have a meter to test the currents etc. Is there a basic package that someone like Hobby King sells? I don't need the glider to be rocket ship, just a lazy climber.

Does anyone have any suggestions?

I'd also like to do the same to my old 2 meter R08 glider if there's enough room up front.

Thanks much,

John Wells

AEAJR 11-21-2015 06:56 AM

The list you seek is in the first post.

aeronca52 11-28-2015 07:43 PM

Quote:

Originally Posted by John Wells (Post 983798)
I have a Spirit 100 with flaps and ailerons that I'd like to convert to electric. It's been high started all of it's life. I'm looking for a list including the bec, motor, folding prop and batteries that I should get. I don't have a meter to test the currents etc. Is there a basic package that someone like Hobby King sells? I don't need the glider to be rocket ship, just a lazy climber.

Does anyone have any suggestions?

I'd also like to do the same to my old 2 meter R08 glider if there's enough room up front.

Thanks much,

John Wells


John,

For what it's worth companies like Heads Up R/C and Altitude Hobbies will give you free advice if you supply them with the info like you posted here. It might be more educational if you find the answers yourself, but for the first one or two times it's nice to have professional advice. Neither company ever failed me.
Jim

AEAJR 11-28-2015 08:03 PM

Quote:

Originally Posted by John Wells (Post 983798)
I have a Spirit 100 with flaps and ailerons that I'd like to convert to electric. It's been high started all of it's life. I'm looking for a list including the bec, motor, folding prop and batteries that I should get. I don't have a meter to test the currents etc. Is there a basic package that someone like Hobby King sells? I don't need the glider to be rocket ship, just a lazy climber.

Does anyone have any suggestions?

I'd also like to do the same to my old 2 meter R08 glider if there's enough room up front.

Thanks much,

John Wells

This should work:
Combo-EZGPro-T3 or Combo-Cularis
http://www.maxxprod.com/mpi/mpi-264.html

tictac 12-26-2015 04:07 AM

I'm quite new to RC planes but I have recently acquired several gliders. One is an old Easy Glider (not electric and not PRO) which I would like to electrify with an outrunner. I have read many posts on modifying this glider. Thank you, AEAJR, for all your contributions. One thing that I have not found much on, is the down & right thrust requirements. I will likely just cut the nose off my EG and attach a motor mount, but could you comment on the angle of right thrust and the angle of down thrust I should aim for. Thank you.

AEAJR 12-26-2015 04:40 AM

I don't have any specific recommendations. I only use a motor for about 30 seconds so if it is not perfectly aligned to the optimum angle I just adjust with the stick on climb. I would put some down and right angle but I can't give you a specific amount. A smidge.

fhhuber 12-26-2015 06:06 AM

Generic thrust angle... Start at about 2 deg right and 5 down.

I've seen planes need 9 down and 5 right. I've also seen them need almost no thrust line offset.

Changing the prop used can change the right thrust angle needed.
Symmetrical airfoil wings tend to need less down-thrust.
Getting the CG closer to ideal can make a plane need less down-thrust.

And other factors affect what angle you really need...

fdnyjery 12-26-2015 03:52 PM

Boy Oh Boy what a great post. I have a few older gliders in the Garage like a gentle lady and an Essence. I would love to covert them to electric .Like said before I am over the Hi- start thing being 71 and living in Florida :o)) Looking at the noses f these planes I am wondering whether to cut the nose at the same type of angle as the nose or would a straight 90 degree cut be a better solution ?Also what do you guys recommend for the thickness of the Plywood motor mount that will be glued on the front ?? Many thanks and I am sure enjoying this new post, hope it goes on for a long time because I am sure there will be a ton of info available and last year I printed out AEAJRs "Everything you want to know about electric powered flight" and that was really great and I learned so much from that manual, I highly recommend it to us new guys. fdnyjery aka Jerry

AEAJR 02-15-2016 05:32 PM

Has anyone done a conversion recently? Tell us what you used and how well it worked.

fhhuber 02-15-2016 06:37 PM

Well... done recently? Yes.

Using new stuff? No... the newest part of the power system is the Dynam 22 purchased appx 12 to 15 years ago...
appx Turnigy 2224 800kv equivalent motor
No label ESC (Its survived 25 amps on 3S) that I forgot what it came out of...
3S 2200mah LiPo

No label servos a little smaller than HS 81
Old DSM2 6 ch RX (label is gone, along with the case)

You couldn't buy any of the stuff I stuck in my Gentle Lady anywhere but a bad swap meet now...

It all works.

fdnyjery 02-15-2016 11:35 PM

Sounds like everything works fine. When Selecting the motor for the glider is the all up weight of the glider what dictates the size of the motor?? thank You fdnyjery aka Jerry


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