ModelTech Extra-300 ARF Electrified! - RC Groups
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Jul 01, 2001, 05:30 AM
Caution:Makes sharp left turns
Troy's Avatar

ModelTech Extra-300 ARF Electrified!

If you want an electric aerobatic experience to match gas performance then check out Mark F's conversion of ModelTech's .25-.36 Extra-300 ARF. This kit is perfect for electric conversion: light, strong, and plenty of space for batteries. ModelTech does it again.

[This message has been edited by Troy (edited 07-02-2001).]
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Jul 02, 2001, 06:09 PM
Registered User
This looks very interesting. They're on sale at Hobby People stores for $80 this week due to the 4th of July sale which make makes me very interested!

Have any idea what the total weight is? Or, how it would perform on a Magnetic Mayhem or one of the new Jeti Phasors? I like the idea, but the Aveox you guys put in there is a little too much for me right now...

Thanks for thge info!

Jul 02, 2001, 08:00 PM
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rcastab's Avatar
Which Jeti motor and battery setup would work for this plane?
Jul 03, 2001, 02:08 AM
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Hi All, I am the person who converted this plane. First off I used the Aveox motor because thats what I had laying around left over from my boat racing days. I think a MM would work great but you would need to gear for no bigger than an 11 inch prop.I had to put bigger wheels and balsa blocks under the landing gear to get away with 12 and 13 inch props but man I tell you this thing will almost go verticle with a 13 x 6.5 prop. It mows the lawn at the same time to.I can't say enough about how much I enjoy this plane. I think any motor setup that can pull a 10 or an 11 inch prop on 8 or 10 to 12 cells around 35 to 40 amps will work great. I dont know jeti motors so hard to say which one. My plane weights just under 5 lbs with 12 cells. also tryed 8 and 10 cells and it flys and lands that much easier with the lighter wing loading. With the sale going on I believe you cant go wrong with this plane. Mark F
Jul 03, 2001, 06:56 AM
Registered User
I got the kit from TOWER several months ago, I bought it to match my OS40LA engine originally. But later I start to play the E-power, so I planned to convert Extra300 to Electric power. It's very surprised and happy to know someone have the same idea. I set up my plane with Jeti Phasor 30/3 and the jeti controller 40-3, Aeronut 9.5x7 carbon propeller, I intend to use 10 Cell RC2400 pack. Now all the stuffs are done, just wait the servos installation. I think I'll have the first flight this weekend or next. I'll post the result later, and welcome any comment and inquiry. Thanks folks.
Jul 03, 2001, 07:18 AM
Registered User
What is the span of this? I have been looking for something to put a Speedgear 700/12 x 8 and 12 cells into, sounds like it might be ideal.
Jul 03, 2001, 03:35 PM
Registered User
Span is 48"
Length is 37"
Wing Area is 377 sq/in

I haven't found any info on the AUW of the airframe alone, but I picked the ARF up yesterday and threw most of it onto a scale quickly to get an idea. I know the fuselage piece with the supplied IC motor mount is 8oz and the two wing halves are 5oz each. The rest of it is the tailfeathers (in bag) at 2.5oz and the various other bits (fiberglass engine shroud ~2oz, the belly pan, canopy, aluminum landing gear bracket and plastic/foam wheels, plus misc hardware. With the IC mount off I'd imagine the weight of the airframe itself to be around 28oz or less. Probably less but that Al landing gear bracket is heavy.

Jul 04, 2001, 10:55 AM
Registered User
I had one of these. Had being the key word . Flew real well on an astro 05 2.38:1 on 10 2400 cells geared with a 12x10 apcE cut down to 10x10 for ground clearance. Cut most of the heavy lumber out of the front firewall to save weight. The similar sukhoi by modeltech looks like it would make a decent conversion for a 16 cell motor.

[This message has been edited by mkurosaka (edited 07-04-2001).]
Jul 08, 2001, 02:09 PM
Registered User
My Extra 300 with Jeti30/3 brushless had a powerful successful maiden flight today. I used 10 cell sanyo 3000Nimh as the first flight power pack, It took off automatically after 100 feet rolling out and had a 30 degree climbing. Extra flight very smoothly but still sensitve and responsive to my controls. I did roll, loop, inverted and other aerobatics, it performed very well. Now talk about the short sides. The Aluminum Landing gear is too soft to withstand the landing force, esp. the hard landing. The propeller was damaged after the hard landing. The second is due to my carelessness, the propeller with the adaptor flight out in the air during the fourth Flight, the plane had a good gliding descend at first, but finally lost control with nose down to the ground. the damage is mild: cracking cowl with mounting block dislodged and the Balsa cracked in head area. I have fix it already. I list the data and equitments below:

Jeti30/3 brushless with 40-3P controller
Aeronaut 9.5X7 carbon prop.(direct drive)
Aeronaut prop. adaptor and spinner(45mm)
Battery: 10 cell 3000Nimh (total w: 1850g)
8 cell 1700SCR (total w: 1700g)
Servo: 3 hitec HS-81
Receiver: JR R610M
Radio: JR388s

Because the jeti brushless shaft is round without flat surface, the hexen mounting screw of the prop adaptor did not engage the shaft firm enough, and cause the propeller flight out in the air. I'll grind a flat surface next time!

The 10cell pack(10400rpm) is powerful for Extra at currency about 35A, but the 8cell(9500rpm) is sufficient to flight easily and lighter at about 25A currency. I'll test other propellers and cell packs later.

Any comment and question are welcome. Thanks
Jul 08, 2001, 02:27 PM
Caution:Makes sharp left turns
Troy's Avatar
JS Chen,
Good to hear you flew it. The landing gear is a little soft but it absorbs a lot of shock on imperfect landings. We flew Mark F.'s out at the gas field yesterday and finally got a good comparison against the gas planes. All I can say is that his really kicks butt. It takes off in about 25-30 ft, pulls straight up and continues to go vertical till you can't see it anymore.
CS you might want to try a bigger diameter prop (10-11")with a little less pitch. Mark's plane had so much more authority when we went to a bigger prop (from a 11X7-12X6). I can't wait to get mine together
Jul 09, 2001, 02:50 PM
Registered User
How was the climb out and vertical performance with the Jeti setup? Do you think it would have gone airborne in less than the 100 feet you first took off in?

Jul 09, 2001, 03:44 PM
Registered User
Hi Jeff:
I think the take-off less than 100 feet is possible with Jeti30/3, if you have a wide good runway and neat tail wheel driving skill. Although I pushed the throt slowly in these flights, I believe Extra could take off within 50 feet and climb by 40 degree if you want. Extra only need about 1/3 to half throttle to cruse. So the vertical climbing and loop is piece of cake when you push the throttle to full. I suggest 10-cell packs to power Extra. My problem now is how to land this beautiful ship nicely and lightly! Maybe I should try to remember the days I land the grow engine ship.
JS Chen
Jul 09, 2001, 04:30 PM
shut up & fly
hoser's Avatar
WOW, you guys beat me to the draw, I was looking at the same model air tech conversion for my astro 05FAI.

Unfortunately, I found at the local hobby store a world models p-47 ARF kit for $80 and put my 05 with an olympus gear drive in it. The Olympus saves me the trouble of reversing the timing and is supper quiet and smooth. The extra is a better scale looking ARF compared to the world models ARF, I should of held out

The extra specs are very similar to the p-47, except for 60SQ. IN. less in wing area, so my power set up should work on the extra also. I fly my plane with 8 cells and a 11 x 8 e-cam prop from hobby lobby.

thanks to help from astrobob, this set up takes off in 30' of grass and will do some vertical on full. I fly mine at half throtle since the fai motor pulls 40+ amps static on full.

i will also try 7 cells on the 11 x 8 prop and 8 2400's cells on an 10x8 prop for longer flights.

model weight is 3.6 pounds and rpm on the 11x8 prop is 6900 and 7500 on the 10x8 prop.

nice job on the modeltech kit !!!! but any good cobalt 05 or even a MM motor should work. on 7-10 cell depending on the final motor.

now I need to see if I can sell the world models kit so i can get the extra.
Jul 11, 2001, 10:31 AM
I'm disoriented!
ChrisD's Avatar
This looks awesome! Out of stock

There's been a lot of discussion recently about using the Kyosho Endoplasama motor vs the MM. What kind of gearing would I use and what cell count and prop size?

Jul 16, 2001, 02:54 AM
Caution:Makes sharp left turns
Troy's Avatar
Today out at the field I got Mark's Extra to sustain hover at about half throttle with a 12X6 APC-E. It was a little gusty but managed to keep it in line for a bit. I didn't think it had enough aileron to counter the torque but Mark put about 3-4 degrees of right thrust in the motor mount (which helped tremendously) and I could hold off the tendency to torque roll. This plane is way too much fun