Buffeting Message Board

From: Mike Newall
mike.newall@btinternet.com
This has been discussed before, it would appear that the original design needs a little re working. Sean de Rosier claims his vortex generators and strake cures the problem. Dick Rihn says his wing fairing helps. We are half way through ours and have yet to decide but it would appear that a heavy One Design will buffet but it still flies well. Contact Sean and try his VG's.

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From: Fritz Guenther
I have fairings and strakes on my 1D and had the same problem as everyone else when they are new to the aircraft. Now that I have learned how the aircraft likes to be flown I have pulled +7g's with no buffet.

You have to load the aircraft and let it carve it's own radius, if you try to keep pulling the stick back and fly it around the corner on the elevator the wing will stall/buffet.

From 170 (app) indicated bring the stick smoothly aft until you have 5-6 g's on the accelerometer and hold the stick in that position, don't continue pulling back. Give it a try before you give up on a great little plane!

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From: Guenther Spitzer
g.spitzer@t-online.de
I think I've tried everything I could come up with. I pulled hard, I pulled very slowly, I put it in a turn and pulled very slowly, I brought it up to 3,5 g's - held it for a while then pulled just a little more, all results where the same it would just not go past the 3.5-4 g's. Of course I only had about 3 hours to testfly the airplane but I must say that your answer does not convince me.
Snap's for example where not possible at all because the tail would stall before I could get the wing to stall - how can I approach snap's without loading up the wing ???
Inverted it was possible to push 5-6 g's easily - no buffeting - what does that tell you ? The wing is fully symetric so the only thing that can create the buffeting is the tail in conjunction with the burbles off the wing ...

Has anyone tried to shift wheigt ????????????
How much does the CG affect buffeting ???????
Inverted stickforce without retrimming was very high on the said airplane - shouldn't it be as light as in the upright position ???

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From: Fritz Guenther
Hi Guenther,

I have not flown my aircraft without the strakes. When Len Fox was doing the flight test program he commented that the tail was stalling first and that we needed to put strakes on the aircraft to correct this. The strakes were made so that they could be adjusted, several flights later Len was happy with the position of the strakes and permanent ones were installed.

As for the difference inverted, others have also commented to me that you could push as hard as you wanted in the 1D without any buffet, several seemed to think it was the relationship of the gear leg to the wing that was causing the difference. Is it possible that the stakes on the aircraft you are flying are not positioned correctly? Dick Rihn's 1D has large wing root fairings that mate to the fuselage up near the fire wall/cowling, I think this helps keep the "dirty" air off the gear leg going under the wing instead of over the top and onto the tail surfaces?

The GC in my aircraft with 10 gal. of fuel and a 230# pilot/chute is 22.42% MAC. I'm a sportsman level pilot who has tried a few snaps in the 1D but not enough "snap" experience to comment.

Any other 1D's in the area you can fly for comparison?

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From: Guenther Spitzer
g.spitzer@t-online.de
Hi Fritz,

thanks for the response. I will be in the US again in April to attend Sun&Fun. Then I will also be able to fly the 1D again. The said 1D is in Tennessee right now and Ray Williams is working to make the 1D fly right. Then I hope I can post more information.

Greetings Guenther (germany)

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From: Scott Riddell
gentle_enigma@hotmail.com
On the G-200 prototype the buffet was independent of airspeed (a factor of AOA) as is reasonable. The method Greg Howard and I used to locate the strakes was to tuft the wing and fuselage and videotape stalls. The flow seperation is quite dramatic and the tufts make it easy to fine tune the placement. The location can be sensitive and this is the only way I know to account for any constructions variations... otherwise it's just luck!
The strakes I built were 1 in. wide and ~4 in. long. Weight ~1/8 lb. (As compared to the later wing farings weighing ~10 lbs.)

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From: Richard Rihn
Rihnairco@aol.com
I have @135 hours on my One Design now. I have been to +8 G's and -5.5G's. I fly Unlimited and Advanced sequences without buffet - as long as I don't resort to the stick handling technique that works so well in a Pitts. That isn't always so easy as I teach in the 2B Tues-Fri and fly for fun in my One Design Sat-Mon. As long as I can remember which airplane I am in it works just fine. A quality (?) advanced sequence takes plus 6 and minus 4.5 G's. I did not add strakes which were a fall back position if my big wing root fairings didn't work. I did not have to add gear leg/fuselage fairings. So it appears that turbulence from the wing fuselage juncture at high angles of attack can buffet and perhaps even stall out the tail surfaces. The fixes are easy if you plan ahead and handle the controls as though you are in a monoplane. The rewards for doing both are significant and well worth the trouble. This is the toughest and at the same time most agile competition aircraft I have ever had the privilege to fly.

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