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Old Nov 10, 2012, 11:25 PM
UMs & parkflyers... for now.
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Second video.
Rufe 2nd Taxi test B (0 min 47 sec)
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Old Nov 11, 2012, 12:39 AM
UMs & parkflyers... for now.
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Third and last video.
Rufe 2nd Taxi test C (0 min 0 sec)
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Old Nov 12, 2012, 09:37 PM
UMs & parkflyers... for now.
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I got much done today:
-- the control throws are evened out.
-- switched out the RX.
-- bound it to a decent radio but, have not implemented any dual rates, expo or travel limits.
-- extended the water rudder.
-- finished the upper panel lines.
-- put some of the kit markings on, sealing the edges with some white Gorilla Glue.
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Old Nov 13, 2012, 03:56 AM
This is a fine fiddly business
Robert R's Avatar
United States, WA, Marysville
Joined May 2009
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David,
It looks like you have slow speed high speed taxi nicely sorted out. Good videos and strong work. I am sure that you will have the in-flight excitement worked out soon. Also, that was a resourceful retrieval effort. Ah, yes, this is a fiddly business.
Best,
Robert
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Old Nov 13, 2012, 04:10 AM
This is a fine fiddly business
Robert R's Avatar
United States, WA, Marysville
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David,
I rewatched the video. Could your CG be a bit aft following the float revision? It looked like the plane was pretty pitch sensitive. It could be control throw as you said but it could also be aft CG. Just a thought.
Best,
Robert
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Old Nov 13, 2012, 04:44 AM
UMs & parkflyers... for now.
davidterrell80's Avatar
United States, VA, Herndon
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I'll be sure and check the CG again, this evening when I set up the dual-rates and expo on the flight transmitter. At the time, I was using one of the "game controller" transmitters for the initial tests; so, I believed the full-throw, linear response of the device was part of the reason. I had been focusing on CG as part of getting the ship to balance "on the step" and will re-examine its relationship to the overall aircraft.

I had my "engineer hat on" at the time and was watching the taxi behavior so intently that the lift off was unexpected. The moment of confusion was followed by wild over-control and the nose dive into the water.
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Old Nov 13, 2012, 07:53 PM
UMs & parkflyers... for now.
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Robert, your eyes did not deceive you. I set the Rufe in flight condition, with the 800 mAh 3S as far forward as possible and rechecked the CG.

The specified CG of the GWS kit is 45-57 mm aft of the root LE. The measured CG of the Rufe was at least 7 mm aft of acceptable range.

I ended up adding about 25 g of ballast to the cowl. I could have gotten away with 20 g if I wanted to cut open the float and insert the ballast there but, I'm getting impatient. I should have made the float/pylon attachments adjustable. I would have moved the main float forward about 1.5 cm.

I also still noticed the elevator throws were inconsistent. Investigation determined that the elevator pushrod was too flexible. It was the source of the asymmetric control throw I would keep running into. So I replaced it with a good sized graphite tube and now, I dare it to flex. The elevator throw is now reliable and even.
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Old Nov 25, 2012, 07:38 PM
UMs & parkflyers... for now.
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I disassembled the Rufe, tonight and did a full inspection of all components. I found one problem that needed to be addressed and repaired it.

As I worked, I took a good set of photos and append them here.
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Old Dec 09, 2012, 02:00 AM
This is a fine fiddly business
Robert R's Avatar
United States, WA, Marysville
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David,
It looks like you have it nicely sorted. I am looking forward to more video, weather permitting.
Best,
Robert
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Old Dec 09, 2012, 08:43 AM
UMs & parkflyers... for now.
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Robert, yesterday was beautiful and calm. I went out to the lake but decided not to fly the Rufe without a provision for rescuing the plane if something went wrong. There was no wind to bring it back to shore.
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Old Dec 28, 2012, 06:13 PM
UMs & parkflyers... for now.
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I had the first flights of the Rufe today. I was by myself, so no video. I launched from grass at my normal place.

Takeoffs were fine.

The Rufe was "twitchy" in pitch so, I think the CG is still a little aft. I'm going to add more battery for useful nose weight. It was very neutral in roll... but I had the Lo-rates set to 85% travel and +50 expo... and, while I could not take my eyes off it, it was not more than a bit of a handful.

I had to keep the speed up. She stalled cleanly, wanting to fall off on one wing, and I needed some speed on her to keep her from beginning to mush. This may also be related to the probable aft CG.

I also think she might be a little under-powered. Getting her out of any impending stall gave me some trepidation. I'll recalculate the power system for more power.

Landings were OK if I kept the speed up. Once, I almost stalled her just above the ground but a burst of max throttle let her grease in.
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Old Dec 28, 2012, 11:26 PM
This is a fine fiddly business
Robert R's Avatar
United States, WA, Marysville
Joined May 2009
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Quote:
Originally Posted by davidterrell80 View Post
I had the first flights of the Rufe today. I was by myself, so no video. I launched from grass at my normal place.

Takeoffs were fine.

The Rufe was "twitchy" in pitch so, I think the CG is still a little aft. I'm going to add more battery for useful nose weight. It was very neutral in roll... but I had the Lo-rates set to 85% travel and +50 expo... and, while I could not take my eyes off it, it was not more than a bit of a handful.

I had to keep the speed up. She stalled cleanly, wanting to fall off on one wing, and I needed some speed on her to keep her from beginning to mush. This may also be related to the probable aft CG.

I also think she might be a little under-powered. Getting her out of any impending stall gave me some trepidation. I'll recalculate the power system for more power.

Landings were OK if I kept the speed up. Once, I almost stalled her just above the ground but a burst of max throttle let her grease in.
Congratulations!
It sounds like you did a fine job of test piloting and after a little sorting out you will have a very nice plane.
Best,
Robert
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Old Jan 12, 2013, 09:55 PM
UMs & parkflyers... for now.
davidterrell80's Avatar
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I moved the CG forward and flew the Rufe today.

It flew quite well but, I have to learn that she is not an Ultra Micro. I must keep the speed up. There's a couple of hours of maintenance in my future. I'm going to add a carbon spar out to the tip floats.

RC Nakajima Rufe (0 min 0 sec)
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Old Jan 12, 2013, 11:48 PM
This is a fine fiddly business
Robert R's Avatar
United States, WA, Marysville
Joined May 2009
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These flights are so much improved from the first flights. You did a nice job of sorting out the CG. Sorry about the repairs. They look more annoying than difficult. This is a fine fiddly business.
Best,
Robert
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