Re: GU vs LS-1 (was Re: Q-talk 155 . . . .)
Sanjay Dhall <sdhall@...>
The following links show results of tests performed on LS0417mod andtoggle quoted messageShow quoted text
One way to compare 'efficiency' of airfoils is to look at Cl/Cd ratios in
our speed ranges.
At this site you can see and compare plots of each airfoil's performance, Cl
and Cd vs angle of attack at various Reynold numbers (a measure of
turbulence). So as an example, doing a comparison at the lowest Reynolds
number of 50k (least turbulent), Cl and Cd would appear to marginally favor
the LS0417mod for angle of about 5 to 10 degrees.
At the time of original design using GU and later redesign using LS
airfoils, the original designers would have looked for comparable
performance, without the downside (flow separation) of GU airfoil.
However, with the GU you add vortex generators. I am not sure how these
detract from efficiency during normal flight.
Similarly, with the LS, you add sparrow strainers. The sparrow strainers
surely add some drag given that they are about 1/4 -1/3 sq. ft. frontal
But I would imagine that, rather than reinventing this wheel, such
comparison must be present somewhere in the newsletters and archives, or
published by QAC from their own research and airfoil choice in the past.
From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
Sent: Tuesday, October 30, 2012 2:32 PM
Subject: [Q-LIST] GU vs LS-1 (was Re: Q-talk 155 . . . .)
I have wondered for a long time, has anyone documented the performance
difference between the GU and the LS-1? and the difference between the
GU with Vortex Generators and without? wind tunnel data? anything?
I think if I was building a single seat Quickie I would use the GU
canard but not otherwise. I suspect either airfoil is better than most
other airfoils. But I have no data to compare them, and no data to
compare the the GU with VGs to the LS-1. I think wind tunnel data
exists, but it doesn't include the VGs. I think you are crazy to fly
behind the GU without VGs (Murphy will get you!).
Anyone got some numbers?
ps: I agree with Sam re the Q2 but not sure about the Tri-Q.
On 10/29/2012 6:01 PM, Trevor Fernihough wrote: