Extra 300 joins weight watchers (Electric conversion challenge)

[Zimmerman]

After converting many 46 sized ARF nitro kits to electric I have become frustrated with the weight penalty that you have to pay when doing conversions so I decided to set myself a challenge to build a nitro kit as an electric and along the way cut the weight as much as possible to get it under 2 kg and make it outperform the nitro equivalent.

The kit I will use is a Great Planes Extra 300 S
Wingspan - 1470 mm
Original power requirement - 46 nitro
Original flying weight - 2.75kg
Electric Power system will be as follows:
Motor - Hacker B50 13s 2800KV
Gearbox - Maxon inline 5.2 to 1
ESC - Hacker 70 opto
Amp draw - 47 amps static
Thrust - approx 2kg+
Prop - APC Thin Electric 14x7
Lippo Battery - Kokam 3200 20c in 5 S configuration
Final Weight target < 2kg

The aim along the way is to make the model as slippery as possible by eliminating any drag from external mounted servos and cut weight by replacing all the heavy hardwood and ply components with lighter materials.

I will also replace the heavy nose cone, cowl and landing gear with lighter equivalents that I moulded myself.

So far the build is progressing well and I am on target

We have the Red bull air race coming to Perth soon and this project was inspired by those planes.

This is the way it will look when it is complete

zim

[cliddell]

she is a bute zim and i can't wait to see it finished if you use that colour scheme it will look like the real one in the photo

happy flying
chris

[Zimmerman]

The undercarridge has been molded up, 2 glass, 11 carbon, 2 glass. This gives it flexibitly as well as strenght all up weight once trimmed and drilled, is 43grams, Original alluminium undercarridge 112.5grams.
Carbon fiber undercarridge has really good felxibility on hard landings. This one time at yokine i shoved a pla, nah just joking. nah one time at yokine i made a really hard landing, and the undercarridge flexed so much, that the wheel pants punched a whole either side of the film under the wing, this was on a smaller model, and much thinner, if I didn't see the wholes I woulnd't have believed that it could be so flexible.

The back elevator horn is all internal using a carbon rod straight through gives no slop.

[zxcboy46]

What a nice work!

[Zimmerman]

Thanks zxcboy46
the new canapy was molded with 0.5m PET and tinted with black.
old canapy 82 g
new canapy 40g

is now ready for covering.

[Boogie3D]

Was the PET from the bottle?? How did you the canopy? What kind of mold has been used?

[Dennis C]

a tutorial on how you laid up the "undercarredge" would be greatly appreciated

Nice work and good luck on the diet

Dennis

[Zimmerman]

Boogie3D,
No it was not from a bottle, but a sheet of PET, 0.5mm thick or 0.7mm.
The mold was plaster

Dennis C,
A TUTORIAL!, gee that's pushing the friendship a bit :D
I hope this does the trick.

1: Glue original under carridge down(if you do not have an undercarridge to mold from, you can bend one up out of tin, or alluminum, or light steel)

2: Wax surface thoroughly 3 times, wax on wax off, make sure you get the side edges

3: Apply ample epoxy

4: lay 2 glass, 11-14 carbon, 2 glass. The glass gives it the flexibility and the carbon will stiffin it up, and make it light. You can choose the amount of glass to carbon, but the more glass the heavier it will be. The above amount will give you approximatley 3-3,2mm thick.

5: Use a fiberglass roller, you can buy these at any hardware store(if you don't have one) Roll every layer seperatly, and if your feeling a bit lazy you'll get away with every two layers. And keep applying resin with a brush as it's required, don't worry about applying too much resin, the rolling will push out all the excess, it's important not to have a dry lamination, this
may cause the undercarridge to fail on a hard landing.

6: Once properly cured, using a dremil cut along the edge, this will be clearly defined and very easy to see.

Goodluck with the project
PS. If you really want a professional finish use peel ply on the last layer

[Dennis C]

zimmerman

But what are friend forr??

that was great!!! and thank you very much, I am starting a Pitts python and that may just have solved one of my problems

Thanks
Dennis

[Zimmerman]

Dennis, glad to help.
Once you make your first carbon undercarrige you will be making one for every model that takes that type.
Zim
video soon.

[Zimmerman]

The end result was close but no cigar, the planes weight exceeded the target by 65grams, total weight 2.065kg

Here is a photo of the plane in action and it flys as good as any 46 nitro I have ever seen, see if you agree when you see the video coming up next

[Zimmerman]

Enjoy!!!

[Tipsy_WA]

Zimm

Your Dog is nuts

[Zimmerman]

One day he is going to get the chop!!!!!!

[Griffin]

Very nice plane and impressive weight loss. Would be interested in more detailed description of flight charactoristics. Thanks for posting, Steve

[cliddell]

great vid zim and great flying marty

chris :D

[RickC2009]

Great video!
Rickc

[Zimmerman]

Steve,
The plane is unbelievably good vertical power, even prop hangs with very little throttle. I'm only running a small 14/7apc the usal setup for this type of plane would be a 16/8, on a 6:7.1 gear box. The reason why i chose 5:2.1 box is to run a smaller prop faster. I altered the aelerons, i made them a bit bigger, but it's not a 3D model; the aelerons would have to be huge, this is definatley a sports plane, it will flatspin, I just need to get the CG back, it's a little nose heavy. Marty the pilot, who flew for the video said he was just getting use to it, after the second battery, and he was getting more comfortable with every flight.

Chris,
How's the green machine going?
Will it be ready for the weekend?

[cliddell]

zimm
maybe ready for sunday but not shore
my new bd 5 is ready for maiden tomorow weather permitting

chris :)

[kraaijer]

Great stuff! I've just made my very first, very own UC with the help of your instructions!

Cool, thx very much!

Ron

[Ron van Sommeren]

@Ron, off_topic
Are you familiar with www.modelbouwforum.nl ?

E fly-in's in Belgium and the Netherlands:
http://www.modelbouwforum.nl/phpBB2/viewtopic.php?t=27467
Idem indoor:
http://www.modelbouwforum.nl/phpBB2/viewtopic.php?t=45172

Do-it-yourself motor homepages, manuals/tutorials, checks and tests in the first message of this motor builders tips and tricks thread. The checks and tests may save you from frying your controller or motor. Thread is active, bookmark it for future refence and subscribe to it:
http://www.rcgroups.com/forums/showthread.php?t=240993


Vriendelijke groeten ;) Ron
• diy motor building tips & tricks (http://www.rcgroups.com/forums/showthread.php?t=240993)
• diy outrunner discussion group (http://www.yahoogroups.com/group/lrk-torquemax)
• int. E fly-in & diy outrunner meet (http://home.hetnet.nl/~ronvans/), Sept.3 2006, Nijmegen, the Netherlands

[GregG]

Very nice Zimmerman, impressive performance! Great flying by Marty as well.

I love that prop noise as it's doing the low flybys. :D