Dynamic Soaring 513 mph

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Passamynd
Sverrir
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Póstar: 11420
Skráður: 17. Apr. 2004 03:33:31

Re: Dynamic Soaring 513 mph

Póstur eftir Sverrir »

Búið að bæta gamla metið um 8 mílur en það gerði Spencer Lisenby í Weldon.

Gefum Spencer orðið.

[quote]Its funny, normally, I can hardly sleep the day before its going to be windy but this time was different. I knew it was raining in the morning so I was actually pretty relaxed. The excitement started to build though when I got to Lancaster and found the highway was closed due to high winds blowing sand and dust. I managed to detour quickly around the closure and got back on the highway a couple of miles later to find a string of overturned 18 wheelers on the side of the road. I think I counted a total of (10) on the drive up. Horrible luck for the drivers but I figured this was a good sign for DSers ;o). Another good sign was that every one of the thousands of windmills at Mojave were parked with blades weathervaned to prevent breakage. When BSP came into sight and I could tell it wasn't raining, thats when I got the feeling this was going to be a big day ;o)

Alan and Stu were already on the hill at Weldon but I couldn't resist checking BSP on the way there. I measured 62mph (sensor says 52G71 for when I was there) before I threw out my 85oz K2m with Alan's airspeed telemetry. It would up fast and the backside was relatively smooth for BSP. As long as you kept the bottom turn low, it wouldn't try to roll you. I got up to 450 something (with the temp set conservatively low) and started wondering if it was blowing 60 at Weldon?? I decided to leave some of the best BSP I'd ever flown in hopes to find the same at Weldon. FWIW, Verizon still doesn't work at BSP...

As I pulled up to Weldon, I got some sprinkles on the windshield and started trying to talk Alan and Stu into going to BSP. It was blowing in the 50s and they weren't interested in packing up so I started putting planes together.
I tested the air with my 85ozer then flew the K130DP. This was a maiden of a new one I had built using some new methods and was eager to test it out. I was also using some different settings to try to prevent the high speed flick problem that I had experienced in the past. Well the new plane and new settings worked wonderfully and I never had any unwanted behavior in any of the flights despite some turbulence. It felt alot easier to fly than in the past with no surprises. It sure was nice to hear the 500mph speeds! Stu got the 509 up at the wall and a few laps later, Alan called shouted out 513mph over the wind! YEEEEHAW! [/quote]


[quote]The recent record flight was the maiden of a new K130 that was made using some new tricks. I also was running some new programming details. I don't think these new construction methods had as much to do with the good behavior as did some of the flight settings.

The whole plane was made without vacuum bagging. I've always felt like the 'cold' joints between cured top and bottom skins were a weak point. Especially since we've relied on filled epoxy and its mechanical adhesion to take all of the loads between the skins. With this build, we used pressure bladders and EPS formers to generate the required pressure for compaction. On the LE, TE, and root face of all of the wing panels, I have 2-3 layers of carbon overlapping the seams and everything is wetted out and cured together at one time. I think this pretty much eliminates the possibility of opening up a seam in a bad landing, or a control surface splitting at the TE.. The bladders are simply oversized poly bag tubing and they are inflated through the alignment pin troughs in the molds. The fuselage has been made this way for some time but this is the first time i've done this with the wing.

The last construction change is that the skins are 3mm thick and are solid carbon ;o)

As for the settings, my main goal was to reduce the possibility for tip stall while DSing. I have crashed (3) planes over the years around 500mph due to fighting turbulence and dealing with the reduced CLmax at higher mach numbers. The first thought I had was that the usual failure scenario involved a large elevator pull combined with large aileron correction. This was pushing the wingtip with the downward deflected aileron beyond its stall AOA. To prevent this, I've set up the outboard flap to allow reflex so it can share aileron duty and reduce the overall aileron deflection needed for a given roll rate. The outboard flap is set up to go 1/2 the deflection of the aileron. The inboard flap was not set up for up travel on this plane so I was not able to allow it to be coupled to ailerons. This might be possible on some of the production models. I also decided to learn to live with a slightly slower max roll rate. At high speeds, its hard for me to use the aileron judiciously when you hit turbulence. I think its best to set the max to a tolerable level so that when I bang the stick all the way over during a hard elevator pull, it doesn't cause any problems. Lastly, I set up the ailerons to use roughly 40% differential for more up than down travel.

I'm also using snapflap to help avoid the tip stall problem. I'm running about 3mm at full elevator stick measured at the root edge of the inboard flap. The outboard flap is using half as much. The ailerons remain neutral. This washes out the wing to prevent the tipstall problem while also helping with bending and twisting loads on the wing. The lift distribution is still OK with this since it was slightly overloaded at the tips to begin with. Lastly, it reduces any unwanted roll input caused by imperfect radio programming (I never get 100% perfectly symmetric snapflap travels).

I hope this info helps with setting up your K130DP for optimal performance. Keep in mind that at these speeds, everything is experimental so I expect the tuning process to be ongoing... Whatever you do, make small incremental changes and proceed cautiously. [/quote]

Mynd

Bara svona til gamans þá eru þetta um 228 m/s þannig að ef vídeó var tekið á 30 fps þá færist vélin til um 10 metra á milli ramma!
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