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Aug 22, 2016, 11:26 PM
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8-22 Test Reports


Greg has been doing a great job at sink rate testing and I will have him post his findings here as things go along.
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Aug 25, 2016, 09:00 PM
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Sink Rate Testing #1


I have three separate sessions of sink rate testing, comparing the Ghost from Shaper Dave with two other DLGs. In the interest of not riling up folks, I've decided to not identify the comparison airplanes. One is a tried-and-true champion of long standing, the other is a current top ship. They were chosen as available.

The reason for not identifying them is because the flight times I'm going to post are what I can achieve, being old, fatish, and stiff in my launch. I'm sure if you have one of these ships, you like it very much, and you should. They are both very nice and were set up initially by an expert.

The technique used calls for patience and discipline. I launch, then fly straight out. I start a gentle turn (inside wing level, no more bank than that) and bring the airplane back. The airplane flies all the way to landing. If one flight turns left, the next turns right. Any lift encountered is simply flown threw - no circling, no returning to lift. I fly three or four flights like that on one airplane, then switch. I find that if I can get 13-15 flights on both airplanes, that I can (with confidence) state that one is showing better sink rate (flight times) than the other.

The results will not support anything like a normal distribution analysis, so a non-parametric approach is required.

This first trial has both airplanes transitioned immediately at the top of the launch to float mode.

12 flights each

Trial Horse A (THA) total flight time: 15:29; Ghost total 19:21
THA shortest flight 0:57; Ghost shortest flight 0:57
THA longest flight 1:52; Ghost longest flight 2:36
THA: three flights less than 1:00; Ghost: one flight less than 1:00
THA nine flights greater than one minute; Ghost eleven flights greater than one minute
THA: no flights exceeded two minutes; Ghost: two flights exceeded two minutes
THA median flight: 1:20; Ghost median flight: 1:38

I feel like the Ghost has definitely done better than THA. I would have no problem calling a 1:40 for a first flight in a poker round, knowing it is a safe bet. Unfortunately, Trial Horse A succumbed to an unfortunate mishap, the elevator coming disconnected on launch. So, there will not be any opportunity to re-visit this airplane.

Yours, Greg
Last edited by glidermang; Aug 25, 2016 at 09:33 PM.
Aug 25, 2016, 09:42 PM
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Sink Rate Testing #2


This is the second set of sink rate testing information. The trial horse this time is different, but still a respected, near-top-end ship. The procedure is the same as for the first set, and compares the Ghost with the Trial Horse B (THB) in float mode, trying to fly at the minimum possible sink rate.

The procedure is the same: several launches of each, switching every three or four flights or so; ignoring any signs of lift (unless flight times exceed three minutes, then there is too much lift to give meaningful results); left circuits of the field alternate with right circuits, and so forth.

15 flights each
THB total flight time: 19:26; Ghost total: 22:34
THB shortest flight: 0:58; Ghost shortest flight: 1:02
THB longest flight: 1:48; Ghost longest flight: 2:17
THB: four flights less than 1:10; Ghost: three flights shorter than 1:10
THB: eleven flights exceeded 1:10; Ghost: twelve flights exceeded 1:10
THB: no flights exceeded two minutes; Ghost: two flights exceeded two minutes.
THB median flight: 1:17; Ghost median flight: 1:24

The data favors the Ghost, although the difference is not terribly pronounced.

The lift really deteriorated after the first four or five flights - it was there, but very soft and very narrow.

Yours, Greg
Aug 25, 2016, 09:49 PM
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Sink Rate Testing #3


This is the third set of sink rate data. Again, the Trial Horse is B (THB), a current and fairly popular model.

The rules are still the same, except this time, the comparison will be in cruise mode.

15 Flights each
THB total flight time: 15:22; Ghost total time: 16:49
THB shortest flight: 0:44; Ghost shortest flight: 0:45
THB longest flight: 1:34; Ghost longest flight: 1:21
THB: seven flights less than 1:00; Ghost: four flights less than 1:00
THB eight flights longer than 1:00; Ghost: eleven flights longer than 1:00
Neither airplane could cruise from my launch height for two minutes or longer - sorry.
THB median flight: 1:02; Ghost median flight: 1:09

The Ghost isn't hugely better than Trial Horse B in cruise flight. It was a good morning for this, as neither airplane showed the slightest signs of lift at any time during the series.

Yours, Greg
Sep 09, 2016, 06:01 AM
Carboweave, Ask For It By Name
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Looking good Dave and Greg.
It was hard for me to imagine what a poly DLG was going to look like when you told me about it. It is just beautiful with nice flowing lines.

Terry
Feb 04, 2017, 06:05 AM
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G2 taking a nap


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