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Old Sep 28, 2012, 04:16 PM
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F35 vtol build thread (It works!)

Hi all,
Been working on my f35 vtol in the evenings since Monday, so 4 days in so far and already have working vtol. So to catch you guys up, its a pretty simple design. As simple as I could think of to make it work well. The airframe is a modified version of rcpowers f35 v2 plans. I then got 3 55mm 4300kv ducted fans from nitroplanes.com matched to some 40esc for the power system. Its being controlled by a hobbyking kk board clone v2.1 with tricopter programming loaded to it. The lay out is that i have one edf right in the front between the two air duct intakes and then two edfs in the rear a bit behind the cg of the aircraft. The front edf pivots left and right to control yaw and the rear two pivot up to project thrust out of the rear for regular forward flight. For the battery im running a 3300 4s nanotech. will vtol just a click over half throttle. Well this is as far as I have gotten so far. When I went to test it I found the transition servo didn't have enough power to hold the rear fans down the way I have my rear hing system so I plan to be working on making a better system for that this evening. (You guys have any ideas?) I had to glue it in the vtol position for vtol testing. Still have to come up with a way to kill power to the front fan after transitioning to forward flight. I cant think of a way to do that through radio programming because of all the controls going through the control board, so what I have come up with is a normally closed micro switch that is pressed by the rear edf mount in the normal flight position to kill the signal wire to the front esc. I think that should work well. I also plan to have the rear fans ducted to the rear with full thrust vectoring when in normal flight. Any thoughts, ideas or criticism is welcome and appreciated! I wanna know what you guys think!

Here is a vid from yesterday evening for you guys to check out. And remember this is just the prototype test bed! This is to get everything figured out and working. Then I will build one that looks much nicer and with the edf units recessed inside so as to not be hanging out the bottom.

RC F35B vtol protype testing (1 min 9 sec)
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Old Sep 28, 2012, 05:21 PM
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Very nice! I'm surprised at the stability you have with the motors so close together on the bottom. Hopefully you can get the transition figured out soon
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Old Sep 28, 2012, 05:49 PM
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Looks great. With the KK, I think a switch on the signal line for the front motor is the way to go so you're headed in the right direction.
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Old Sep 28, 2012, 09:15 PM
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Thanks guys! Wonder if I should have posted in the scratch built edf section? I posted here because it is obviously vtol but its also a scratch built edf! I think more would probably see it there.
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Old Sep 28, 2012, 10:38 PM
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Perfect place IMO. You're on your way
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Old Sep 29, 2012, 09:00 AM
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Great job superchomper, congratulations! Looking forward to watching the progress on this project. Best of luck.
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Old Sep 29, 2012, 11:32 AM
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Thanks! I had builders block last night! I was all ready to get home from work and get to work on it but when I sat down at my workbench I just went blank! Just wasn't having any good ideas and couldn't figure it out so after a few hours of frustration I went to bed. My dad always said when you cant figure something out stop working on it and sleep on it and it will come to you. Guess he was right because I woke up a little early before work this morning and looked at it and got much more accomplished in a few minutes than several hours last night.Got the front fan recessed inside the fuselage and its going to have a hatch that opens on top like the real f35B to allow air for the front fan. On the rear fans I still have to come up with a hing system to allow them to pivot up and down that's not not much strain on servos. Hinging it on the edge doesn't work because the thrust of the fans is to much for the servo to overcome and I don't wanna add like 4 servos because of all the complication and extra weight. I think I need to make it pivot on the center somehow so that the thrust will push against the mount and not the servos but im not sure how to do this because I cant have much foam on each side of the edfs and have it sill fit inside the fuselage. Any ideas?
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Old Sep 29, 2012, 11:33 AM
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Hi....I am glade that someone have the couragge to make a vtol plane with Kkuk board!....Shame on me..
Cheers and goodluck!
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Old Sep 29, 2012, 02:00 PM
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Originally Posted by superchomper2003 View Post
...I think I need to make it pivot on the center somehow so that the thrust will push against the mount and not the servos...
I agree. Remove the motor and put a carbon rod through the center. Rough up the carbon rod and the edf unit with sandpaper and glue it in place with JB Weld glue. then you can cut out the carbon tube from the inside of the fan and you'll be left with a perfectly straight stick on each side that you can support with bearings glued into the the foam side walls of the jet body.
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Old Sep 30, 2012, 02:46 AM
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Thanks for the input guys! Actually I think I have come up with an idea for the pivot, I have to different size aluminum rods, one size fits inside the other. The smaller size will be glued into the foam on each side of the edf center and inserted into the larger rod that will be in the sides of the fuselage. I already have the front edf recessed inside the fuselage. The hinge on the rear setup will allow the rear edfs to be concealed inside the fuselage also. The front edf will completely draw its intake air from the upper hatch that will open when in vtol mode, and the rear edfs will draw primarily from the front intake ducts but have additional air to be drawn in from the rear of the upper fuselage when in vtol mode. This design is meant to fly well, and look as scale as possible (as in not have fans or props visible in areas they wouldn't be on its full size counterpart) while still being easy and cheap to build.
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Old Oct 02, 2012, 12:19 PM
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Well the weather was terrible all weekend but yesterday evening I got a little break from the rain and went out to do some more testing. I got the rear hing system working and hinged in the middle now and the servo has no problem with the transition. I did move the rear edf units closer together to have room to make the pivot system work and now only have about 1 inch in between them. This really took some stability away it was very stable before and now is a bit more twitchy but its manageable. I do have something very crazy going on though. Untill now I have done all of my testing on grass. Yesterday evening I was flying off of a concrete runway. For some reason it wouldn't lift off the ground even at full throttle. It would just make a ton of noise and sit there. But put it on grass or lift it up and let go of it and way it would go. Anyway before I figured this out I was messing with the gyro gains trying to find a reason it wasn't putting off enough thrust to lift off and forgot to turn them back up and it was a little to much for me to handle she went down and banged the back of the fuselage up on the rear a bit but I will get her fixed back up and do some more testing soon.
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Old Oct 02, 2012, 01:02 PM
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...Yesterday evening I was flying off of a concrete runway. For some reason it wouldn't lift off the ground even at full throttle...
Grass is probably acting like landing gear in raising the aircraft up further away from the hard dirt surface which allows more air to the rear fans.

The rear fans seam to be covered on top so the only way for most of the air to get to them is from the bottom. Also if the bottom of the fan is closer to a hard surface, then it can't draw in as much air either.
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Old Oct 02, 2012, 05:24 PM
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Yeah Im sure the the rear fans could do better with an air intake up top like the front. They are only about an inch from the top of the fuselage when in vtol position. The problem is that Im running out of space! I could conceal it like the front except the only place left to mount the battery is directly over the rear Edf fans. I guess I could possibly come up with something in the lower part of the fuslage but then that would obstruct the airflow when in forward flight. This build started off easy but is starting to get more complicated. But I will keep working at it untill I get it. Do you guys know of a switch that could plug into one of the extra channels on my receiver to cut the signal wire power to the front edf?
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Old Oct 02, 2012, 05:27 PM
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Originally Posted by superchomper2003 View Post
Yeah Im sure the the rear fans could do better with an air intake up top like the front. They are only about an inch from the top of the fuselage when in vtol position. The problem is that Im running out of space! I could conceal it like the front except the only place left to mount the battery is directly over the rear Edf fans. I guess I could possibly come up with something in the lower part of the fuslage but then that would obstruct the airflow when in forward flight. This build started off easy but is starting to get more complicated. But I will keep working at it untill I get it. Do you guys know of a switch that could plug into one of the extra channels on my receiver to cut the signal wire power to the front edf?
You might be able to do it with the Tx depending on which Tx you have.
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Old Oct 02, 2012, 05:27 PM
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I forgot all about an old servo as a switch. That could be used in place of the micro switch.
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