Micro Vortex Generators

[comancherookie]

I am considering installing micro vortex generators on my 64 Comanche 250. There have been no posts on VG's since 2002, so I'm hoping to generate a little more discussion on the topic. I routinely fly out of airports 4,000 feet and higher, so the micro VG should help, especially in hot summers. I would like to know if one of you airflow gurus out there know if micro VG's would help keep the boundary layer at higher altitudes and allow a lower pitch angle at cruise. Since most of my flying is at 10,000 feet and above, if I could fly with a little less drag caused by increased lift and a lower angle of attack, I could reduce my prop and perhaps save a few dollars of this $5+ gallon fuel without sacrificing speed. It could be that the micro VG's are shielded too much at higher speed to help with lift at altitude, but I don't know. Hence this post.

[ics-12766]

The VG's installed on a twin I fly decrease Vmc about 10 kts and stall speed about 5 kts. Per STC. Definitely worth it on a twin, just for the Vmc factor. As for cruise, my gut feeling has been that they cost a few kts. Can't back that up with "testing", my VG's were installed before I flew the airplane, however, a similar airplane without VG's is 5-8 kts faster. Not necessarily VG's, the faster airplane also has 2-bl props.

Just MHO, I'd likely not install them on a Comanche single unless I was routinely operating from a short strip.

[rstan]

Hi Rich,
I have VG's on my PA30. I was not aware of any Vmc or stall speed changes. Were you referring to the PA30 ?
Regards,
Richard Stanley

[Zach Grant L1011jock]

If you want high altitude performance increases, the best way to do that is to install full span gap seals. I like th K2U version, but others also like the Webco version. It has been my experience that doing this mod alone increases the optimum altitude of the aircraft about 1500 feet for Comanche singles. Climb rate is also increased so you get to altitude quicker, or you can cruise climb faster at the same verticle rate. From what I have heard others say on the subject, and it makes sense, is the VGs on the singles lowers the stall speed, costs a little in top end, and doesn't do much else. If you operate in the stall regime ofteen, such as very short strips/slow speed patrolling, then I think they would be worthwhile. Anything much over 80MPH indicated should not get any added effect from them. The Comanche wing is already a marvelous piece of engineering at keeping airflow attached. Clean it up a little more and it is unbelievable! My 180 regularly lives in the 15K-17K altitudes, and does just fine!

-Zach

[ics-12766]

[rstan]

[ics-12766]

[Scott R Morris]

[Zach Grant L1011jock]

[ics-12766]

[ics-12766]

[MULEFLY]

[N8962P]

[Zach Grant L1011jock]

[ics-12766]