Thread Tools
Jul 31, 2018, 01:09 PM
Registered User
nhk750's Avatar
Thread OP
Build Log

Great planes extra 300s, 60 size electric conversion


The title is a mouthful, and yes, this is one of the last Extra 300 kits ever made by Great Planes. My wife got me this kit for Christmas and we had to wait about two months to get it as it was backordered. I will most likely kit bash the crap out of this one as I am converting to electric and may do some tail feather mods, like counter balances, to it. I wont start this one for a few months but thought I would start a thread on it to get any ideas others may have for the build.

I just ordered a power system, after much thought and study, and I am going with pretty much the same power system as my Hog Bipe, this should yield about 150-200 watts per pound. I was going with a smaller motor at first, but then I thought it might be fun to make this plane a speed demon or mess around with some 3d and I need a little more power for that than the 4020 motors could give and the 4025 is only 63 grams more weight. I can put up to a 16" prop on this plane, but I thought it would be fun to mess around with props a bit and put a 3 bladed 14x9x3 MAS on it. The calcs, which have been very accurate for me, show it to fly around 70+ MPH with this setup.

6s battery (Turnigy 4500, 30-40c)
Scorpion SII-4025-520KV motor
Master Airscrew 14x9x3 - 3 bladed prop for scale look and speed or 15x8 Xoar electric prop for all around flying and some 3d
Castle Phoenix Edge 100amp ESC
Castle CC BEC 2.0 (14 amp BEC)
Sign up now
to remove ads between posts
Aug 09, 2018, 05:05 PM
Registered User
nhk750's Avatar
Thread OP

Power system procured


I managed to obtain all the power system parts, motor mount and servos for the build. I may need one more servo depending on if I choose to go with a dual servo elevator or not. I'm not so much interested in 3d and am gearing more towards precision sport aerobatics and some speed for fun. It should hit around 70+ mph with this setup. I will start this one in the fall, so no more updates for a while.
Aug 09, 2018, 08:38 PM
I just want to go fly!
walter3rd's Avatar
apc prop for speed!
Aug 10, 2018, 09:03 AM
Registered User
nhk750's Avatar
Thread OP
I have a few Xoar props also and might get another larger MAS 3 blade to experiment with eventually. The 14" might not be enough for slow speed flight and this plane has clearance for a 16" prop. The calcs show the 14" 3 blade to have the highest top speed, but the APC 2 blade props are faster. I just wanted 3 blade for scale looks.
Aug 10, 2018, 02:02 PM
team sleprock
whiskykid's Avatar
this is a "GREAT PLANE"

I originally built mine to spec! and she flew great right off the board, had an Osfx .91 plenty of power!

I am in the middle of a rebuild, with a RCG 20cc gasser!
with that said, I did add 1/2" too the rudder, in hidth and width! ta help wing waalking in high alpha!
and took the ailerons off a crashed Chinese extra 300 witch about doubled the size of ailerons!
never had an issue with the elevator, (plenty of authority) so have not really done anything with it, but if you want ta add counter balances, it should only help!

now with all that said, she does come out a lil on the heavy side, too be a hardcore 3D model!
I have not finished my mods yet, so no flying data too back up any mods, just what I have done after some extensive research!!

the control rods that come with the kit worked great at first, but after a few years of flying with nitro, did gum them up! shouldn't be an issue if your going electric!

here's my old thread, on some of the mods I talked about! https://www.rcgroups.com/forums/show...ight=extra+300

good luck and keep us posted!
Aug 10, 2018, 03:56 PM
Registered User
nhk750's Avatar
Thread OP
Thanks neighbor!
Aug 11, 2018, 09:03 AM
I just want to go fly!
walter3rd's Avatar
I agree the 3 blades look sweet
Aug 12, 2018, 07:53 PM
Low And Slow 3D Pilot
OliverW's Avatar
Put some triangle stock sticking off the front of the leading edge to reduce a stall. One of the guys at our field did that to his extra but did not make them big enough.
Aug 12, 2018, 07:56 PM
Low And Slow 3D Pilot
OliverW's Avatar
It is a design from full scales. Sorry about my banter lol. Just want it's nasty tip stall tendency to not be a problem with you.
Aug 13, 2018, 01:17 PM
Plane Crazy
gwyers's Avatar
Quote:
Originally Posted by whiskykid
this is a "GREAT PLANE"


here's my old thread, on some of the mods I talked about! https://www.rcgroups.com/forums/show...ight=extra+300

good luck and keep us posted!
I second whiskykid... this is a Great Plane!

I have one I built and added 1-1/2" to the rudder and 1" with counterbalance to the elevator and servos in the tail. I'm running an RCGF 20cc which fits in the cowl, and it pulls it around nicely. I like this plane so much I bought a second kit.

Balance for you electric setup is going to be tricky. I ended up mounting my 55g tail servos (1 elevator, 1 rudder) in the tail to offset the heavy gasser motor, but that added too much tail weight so I had to mount the batteries up on the engine box. My second kit will likely be two smaller 25g elevator servos in the tail, and standard size pull-pull rudder servo mounted in the fuse.

I would recommend building the tail light, with the intent of putting your servos in the fuse under the wing as far forward as possible, and you can always move them to the tail later if you need more tail weight.
Aug 13, 2018, 01:31 PM
Registered User
nhk750's Avatar
Thread OP
Nice, looks great! So far all my electric conversions run a nose heavy and with a 6s battery this one should be a little on the nose heavy side too, but we will see. I think I got the last kit they made, itís a shame as they had some cool kits
Aug 13, 2018, 01:37 PM
Plane Crazy
gwyers's Avatar
Quote:
Originally Posted by OliverW
It is a design from full scales. Sorry about my banter lol. Just want it's nasty tip stall tendency to not be a problem with you.
Unfortunately I've had to make a couple of dead stick landings short of the airfield due to mechanical problems. First one was overheating due to lack of an air exit on the cowl, and second one when the pickup line came off inside the fuel tank. Both times I knew I wasn't going to make the runway and was going down in high (1-2 feet high) grass so I bled off remaining airspeed to sort of "plop" the plane down.

The first time the gear caught the grass and flipped her over but I was going so slow there was zero damage. The second time I thought I was clear of a ravine that runs behind our runway when I was setting her down but wasn't. The gear caught the edge of the ravine. I couldn't see the plane due to the high grass and feared it fell into the ravine. Upon approach of the plane it looked like a perfect belly landing 6 feet from the edge, and my gear were dangling on the edge of the bank. It ripped my gear off but no other damage. That's another mod I made. I reinforced the gear mount with thicker ply and extra braces, then mounted the gear to the fuse with wing bolts through tapped holes. The bolts broke and nothing else.

In both cases, I was going very slow on touchdown and zero damage. In neither case did I, nor have I ever experienced a tip stall in this plane. Now let me go find some wood to knock on...
Aug 13, 2018, 01:43 PM
Low And Slow 3D Pilot
OliverW's Avatar
Ok. 2 people at my field had a terrible tip stall on theirs. Wonder if it is just the pilot then lol.
Aug 13, 2018, 01:57 PM
Low And Slow 3D Pilot
OliverW's Avatar
But I doubt it though
Aug 13, 2018, 02:02 PM
Plane Crazy
gwyers's Avatar
Quote:
Originally Posted by OliverW
Ok. 2 people at my field had a terrible tip stall on theirs. Wonder if it is just the pilot then lol.
There are a number of factors that could contribute to tip stalls.
  1. It could be how accurate the wing was built.
  2. The kit comes with some jigs that need to be used when sheeting the wing to prevent warping and I presume holds the correct washout that helps prevent tip stalls.
  3. Lateral balance needs to be checked as well. If you have a gross imbalance from wing tip to wing tip, this could contribute.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Great Planes 60 size Extra 300s Conversion scott282 Glow to Electric Conversions 23 Dec 27, 2018 11:28 AM
Discussion Great Planes Extra 300s 60 size trident58 Glow to Electric Conversions 5 Nov 29, 2014 02:14 PM
Help! Great Planes Extra 300S .60 size buddek09 Fuel Plane Talk 15 Sep 28, 2012 05:34 AM
Discussion Great Planes 46 size Extra 300 to electric bluefork Sport Planes 3 Sep 23, 2009 12:29 AM