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Feb 25, 2020, 01:56 PM
"I will return" Federico
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Maiden Flight - Extreme Flight 104" Extra 300 EV2

After more than a year (off and on construction) I finally finished the build, and conversion to electric, of the new Extreme Flight 104" Extra 300 V2. I'm calling it the EV2. IMAC contests and practice took a lot of my time during the flying season last year, so the build itself took less time than the calendar dates indicate, and even less time than just planning and researching the best options for an electric version.

Major revisions to the airframe:
  1. Modified wings and ailerons to accept a single servo (Futaba A700), rather than two per aileron, and buried the servo in the wing to reduce drag and align the servo arm with the movement of the aileron control horn.
  2. Modified rudder servo compartment in the tail to bury the servo (Futaba A700) in the fuse to reduce drag and align servo arm with the movement of the rudder control horn.
  3. Modified motor box structure to accept a battery tray that self aligns on insertion, is pinned in place to avoid bolts, and automatically connects to the ESC and voltage sensors.
  4. Modified canopy with pins and CF reinforcement to tie both sides of the motor box together where part of the original fuse structure was removed.
  5. Automated canopy locking using a DPDT switch and Actuonix linear servos to reduce time removing and replacing the canopy to reload fresh batteries.
  6. Automated ESC arming using a DPDT switch, an Actuonix linear servo, and a Jeti Anti Spark Connector

Adding these custom options required time to design, test and build. The battery tray uses some 3D printed parts that make this tray a vast improvement over a similar tray I made for my 87" Extra a few years ago.

Some photos and schematics of the build are posted here, but I will be adding the remainder (well over a hundred!) in the next few days.

I hope to get some video of this sweet flying plane soon. Below are some of the pre-flight and post flight pics taken at the maiden on Sunday, February 23.

Field temperature was below 50F with winds about 10 mph down the runway. I didn't perform any aggressive maneuvers like a snap roll or the crazy stuff 3D guys do, just slow rolls, reverse 1/2 Cuban 8s, and a couple humpty bumps with aileron rolls up and down. Once I got the plane trimmed out she flew beautiful lines without any mixing. CG ended up slightly behind the main spar, which is perfect for aerobatics.

I should have stayed at 50% on the throttle until batteries were cycled a few times and the temp outside was warmer. First time I went to full throttle in a vertical climb it felt like the power cut off at about 500 feet up. Came back to the runway basically dead stick. (I didn't know it at the time, but I still had 50% power available, but I didn't want to touch the throttle in case it might damage my ESC.) I got her safely back on the ground, checked everything, took off again, and same thing happened when I went to 3/4 throttle on a 45. Third time I landed for good. Checked the ESC log when I got home. I had set a min voltage at which the ESC would throttle back to 50% to save the battery. Forgot about that. And it was set too high at 43V. I will reset that to 38V. With temp below 50F and brand new batteries they weren't able to hold voltage under load. They will need to be cycled a few times, and flown in warmer weather.

Other than the power issues, the plane flew well. Feels like a real floater.

Thanks to Ray Morton for helping me with the pre-flight prior to the maiden, and for the photos of me with the plane. Thanks, Ray!
Last edited by rclad; Mar 04, 2020 at 01:24 PM. Reason: Added photos.
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Feb 25, 2020, 11:48 PM
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VERY well done. I am impressed with the technical engineering and workmanship. Congratulations on a beautiful job. I hope you get many years of enjoyment from this outstanding ship !!!
Feb 26, 2020, 10:35 AM
"I will return" Federico
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Thank you! It was a lot of work, but I think it will pay off in good performance and enjoyment at the field.

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