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Old Aug 14, 2009, 04:12 PM
The thruster don't work!
Roy E Oetting's Avatar
Fairborn, OH
Joined Oct 2002
414 Posts
The 5 gram motor pusher is no longer the 5 gram motor pusher. I've replaced the out runner with a 12 X 20 10300 KV in-runner. I also replaced the prop with a GWS 2.5 X 1.0 . That is a small prop but the high KV motor will only swing a small prop or it will cook itself. I tached it at 44189 RPM and that was the same battery that I flew with and it hadn't been recharged. The "speed rule of thumb" is pitch (in inches) multiplied be the RPM (in thousands) gives in an approximation of air speed in MPH, so this little guy should go around 44 MPH and watching it in the video it looks pretty close.
I'm ready to build another one with a few changes. I think I will add a .5 x 1 mm carbon rod to the leading edges to stiffen up the wing. I'll spread the main gear so it doesn't have a tendency to tilt over. I need to relocate the receiver to allow moving the battery aft to adjust CG.
Hopefully the next time I fly there will be someone present to shoot the video, and then I'll put some more stick time on her.
Roy
30XPusher20090814A (2 min 47 sec)
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Old Aug 14, 2009, 05:57 PM
The thruster don't work!
Roy E Oetting's Avatar
Fairborn, OH
Joined Oct 2002
414 Posts
Here are a couple of pictures that I used in the video. Looking at the rear view you can see how I can streamline it and expose more prop to the free air. Even though the prop is considerably smaller and there is more ground clearance by keeping the prop high and streamlineing the fuselage it should result in a more efficient system. If the prop was to be lowered it would be hiding behind the wing and the lower fuselage. The air going to the prop would be turbulent with the angle of attack constantly changing. By streamlineing the aft portion of the fuselage the air going to the prop will be cleaner. This should result in less noise and more speed.
Roy
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Old Aug 19, 2009, 11:39 AM
The thruster don't work!
Roy E Oetting's Avatar
Fairborn, OH
Joined Oct 2002
414 Posts
Hi, I just modified the landing gear of the 30X pusher. The plane had a nasty habit of tilting over on takeoff caused by the torque of the prop. I've widened the stance which should eliminate the tilt over. Because of the weather I haven't had a chance to test in thoroughly but I did some high speed taxiing in the parking lot . I've left the cross bar between the wheels intact. I can cut it out later and if that makes the gear to springy I can put a bar back in. I typically make gear like this with the cross bar in place because that guarantees the alignment of the axles. When the glue has dried I cut the cross bar out. In this case I'm going to leave it in and see how it works and then cut it out and see if there is any noticeable difference. The points where the axle meet the landing gear strut are glued together using Kevlar thread and CA. I took a black marker to the joints to neaten it up a bit. I've never had one of these joints fail on me. In this case, because of the cantilever, the moment force at the joint is greater and I might see a failure.
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Old Aug 26, 2009, 04:50 PM
The thruster don't work!
Roy E Oetting's Avatar
Fairborn, OH
Joined Oct 2002
414 Posts
Today I was experimenting with a helmet cam, my bicycle helmet with a couple of cameras mounted on it. I still have to do some adjusting but I'm making progress. The enclosed video shows better how the 12X20 in-runner works and how nice and stable the plane is on the ground. In the past she would tip over on take offs and landings. Today I flew two nice flights. The only problem is that she is really noisy and I won't be flying it in the local parking lot anymore.
30X Pusher & New Motor (1 min 55 sec)
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Old Oct 05, 2009, 04:49 PM
The thruster don't work!
Roy E Oetting's Avatar
Fairborn, OH
Joined Oct 2002
414 Posts
Went to get in a quick flight today and just as I rotated there was a strange noise. The prop had shredded. What caused the over stress I'm not sure. - change in angle of attack at rotation, just the prop twisting in clean air since the shatter happens at the point the prop gets past the fuselage. It wasn't a ground strike because I have a fin to preclude that. It could have been a pebble but I wouldn't have expected both blades to go. Here is the picture.
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