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About Madhatter

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    Charleston, sc
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  1. If it was it would have been almost not possible to be accurately measured. My minimum speed to maintain level was 20 knots indicated with vg's and 25 knots indicated without vg's all at approx 3600 rpm. This was done at 2000 ft at about 85 °F.
  2. There was no significant difference that I could tell.
  3. Those configurations are not valid for the vg analysis because of too many variables involved. Power on stalls, accelerated or straight have too many variables, pilot skill, propeller pitch, engine power, aoa, etc. Slips would be even worse. The key to vg performance is at what point the boundary layer separates from the wing. Power on stalls would only be done to verify no unanticipated issues if indeed the vg's were to be installed permanently. Even trying to analyze landing performance is difficult to get repetitive data due to so many variables. Power off stalls and a few others will have no variables if temp and altitude remain close for all tests. This project was far more involved than I anticipated.
  4. Final thoughts on vg's after 3 weeks of testing(and $500) In the last 3 weeks I have tried the vg's from Micro AeroDynamics at 6, 4, and 2% of chord on both the wings and stabilator and at each time flown the CT in all different configurations. Power off stalls, min airspeed level flight, deep stalls until falling out, all at different flap settings. Also flaring high to see if the bottom drops out. The last test was yesterday after installing Stolspeed vg's on the stabilator at 2% chord which are twice as tall as Micro AeroDynamics vg's to make sure I had full boundary layer penetration. Within an hour after that last flight is the most important test, removal of all vg's and fly without them doing the previous flight tests. There was no significant change with the Stolspeed vg's over the Micro AeroDynamics vg's. The reduction in power off stalls was minimal, maybe 1 or 2 knots, all the other stall configurations were similar. As far a dropping out on landing they helped a little. The problem with that is as you do many high flare tests , you get better at managing them and they are all done in smooth air with no gusting to be consistent so it's difficult to compare. The changes for the better are : min airspeed level flight 20 kts indicated vs 25, more stability in stalls with better aileron control, deep stalls handle better, maybe some better landing. In my opinion vg's don't warrant the cost and installation time. The CT is very efficient aerodynamically, kind of like some of the high performance sailplanes I have flown. I have always considered the CT to be a poor primary student trainer. The stall characteristics are so good that the student who learns in a CT then buys a Cessna 150 and does a full power stall------- welcome to the world, and if the ball isn't centered------welcome to aerobatics. I have to thank Anni Brogan, owner and test pilot for Micro AeroDynamics for all the help in the vg test process.
  5. I've been using the composiclean spray wax for the last 8 yrs to clean the plane. Doesn't take long.
  6. 8% is not a huge amount so determining exactly where stall is, requires consistent accuracy. After a great many stall sequences you get better at consistency. According to Micro AeroDynamics 8 to 10% is an average reduction for most aircraft. The behavior of the aircraft under different configurations is the real goal. This turned out to be more involved than I realized in the beginning. I am trying to finish this before any large fall temperature changes occur so that the flight variables don't change .
  7. I am using vg's on wings and stabilator and there has been no change in cruise speed with any configuration. Any increase in drag from the vg's is countered by the decrease in drag due to the smoother flow created by them which is typical on most aircraft. No change in 310 either, but reduction in vmc is tremendous and that's what kills most people. As for the j3, it's a cub, goes nowhere fast anyway but reduces stall from 39 to 23 mph, a high drag but high lift Clark Y airfoil. I put 100 hp on the cub so no reason to even try to analyze speed difference.
  8. An update on vg's So far I have been able to reduce the power off stall speed by 8 to 10% based on 15° flaps Easy take off speed at 30 kts Made landings with 30° flaps with intentionally high flair and I have positive stabilator control all the way to touchdown, no tendency to drop out. Min airspeed, level flight , no descent at 20 kts indicated at 2000 ft. The main issue with the CTSW is stabilator boundary layer control. It's a difficult issue to resolve, I have done several changes on % chord and lots of flight tests. I have one more test to do and that will be to try Stolspeed vg's on the stabilator. They are 1/2 inch in height vs 1/4 inch on Micro AeroDynamics and might be able to get more bite in the boundary layer which might be partially blanked out with full up elevator, who knows. Installing vg's on an aircraft that hasn't been done before takes a lot of work, I am sceptical of the other CT that tried it as there were no specifics reported and his % chord definatly does not work on mine, not even close. After all the vg tests then all vg's will be removed and flight tests are done again to reverify the difference prior to final vg installation. All this is the way it's done even for certified aircraft, just takes time.
  9. Not something I am going to do, that gets into some serious testing and fabrication issues. There are still some flight tests I have to do. Stabilator VG's are usually always combined with wing VG's as there are sometimes issues with aileron effectiveness if none are used. I have noticed some possibly positive characteristics even with no reduction in stall speed. Time will tell. The CT is a great plane without changes, my goal is to make the landing characteristics better. In the end I may not change anything but at least I will have some answers and will learn a lot from Micro AeroDynamics.
  10. Wouldn't even consider one, however it might put a little pressure on Rotax to be a little more realistic on price structure. Competition is always good for the consumer.
  11. I have completed the vg tests on the CT and I have the results Prior to installing the vg's I made several flights to get baseline accurate numbers on stall speeds with different flap configurations. Stall speeds were done by using accepted methods, (initial entry speed, one knot per second) etc. The vg's were installed at 6%, 4%, and 2% chord of the wing and flown several times in each configuration. The stabilator vg's were placed at 8% chord of the stabilator. In all the flight tests there was no reduction in stall speed in any configuration, however the plane had no tendency to drop out of a prolonged flair, which was my main complaint about the CT. In talking with Micro AeroDynamics the consensus was that the stall strip initiated the stall and the vg's became ineffective at that point, they had seen this before. Eliminating the stall strip would change that but it's not something I would ever do or recommend. At this time I am going to continue to test the vg's on the the stabilator for better landing characteristics without the wing vg's which are ineffective.
  12. I've been using e- prop for while now, climb is 5200 and wot is 5500. Anything over or under 5500 wot, it underperforms.
  13. All VG's are pretty much equal in performance. I have always used Micro Aerodynamics as I prefer certified quality and they are aluminum. The advantage is that Micro AeroDynamics will help in the determination of vg location based on their 35 yrs of engineering and test data. There is no specific airfoil data that I can find for the CT and any help will save me a lot of time. I should start working on the baseline flight data prior to installing the VG's in a few days, hopefully there will be significant result.
  14. Micro AeroDynamics vg's are low profile compared to others and I have never had a problem washing. Just can't use a sponge over them.
  15. The VG's will also be on my stabilator to keep it flying at low speeds.
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