Profili and Xfoil combo.

[Tony D.]

Anybody else using Profili with XFOIL?

You can draw up airfoils or modify existing sections and import them into Profili and check/compare Polars etc.

http://www.rc-soar.com/profili/index.htm

I am thinking that this could be the tool for a poor mans DS optimized airfoil.



Tony Dempsey

[LWThompson]

Would you post an example of what you are thinking of?

[Tony D.]

Hi LW,

These comments by Mark Drela:

"I also did a quick look at a 50/50 blend of the MH24 and E231, and that also seems very good.
An 8-10% narrowing is probably more appropriate with this section. Might be a good less-radical first step." and Craigs' posts from this thread:

http://www.rcgroups.com/forums/showthread.php?s=&threadid=120048&perpage=15&pagenumber=3

got me thinking about an absolute optimized DS section for a specific planform/wing design/speed/flight profile, in this case I want to take my Rimmer design to the limit.

I flew the 2.54 metre Rimmer E231 wing and while I don't have a radar gun and so can only guess at the speed I attained I can say that it was motoring right along so perhaps a DS optimized E231 could be a serious contender for 250MPH.

I will post anything that I come up with.



Tony Dempsey

[Bart Vaio]

Also I don't think there is a "DS" silver bullet airfoil so to speak. From my travels i have found different sites lend themselves to different flying styles and planes. a few sites that work on our easterlies can have near perfect seperation, in 10 to 15 mph wind you can attain clean 150mph speeds. Often times I see pilots using these conditions by banging turns and really using the clean dead air on the back side. Other sites that might work on west winds might blow harder, not have perfect seperation, possibly a lil bumpy on the back, but has ton's of energy, even more than you can use. Some of these sites seem to favor a plane with higher wingloading and slicker airfoils so they can cut thru the bump and the boundry layer better. Also the places I have been flying are in the dense cold air at sea level which some people believe is harder on planes structures. these are all design criteria that maybe should be taken into account when building "YOUR" DS weapon. I personally am not going to build a ds plane for Parker of Kiona Butte cause I spend most of my time at sea level, not 3000+ ft Maybe Mr. (Dr?) Drela can comment on the design benifits from different flying styles vs.air viscosity and Altitude etc. That's why they call it "Dynamic" right? :)

[Tony D.]

Bart, your comments are well taken, I agree that there will be no one plane for all sites but I was hoping to get a high level of performance accross a range of conditions.

So if not a DS Silver bullet airfoil maybe a Bronze bullet working in concert with and optimized airframe, planform etc.

The site I fly at is Interior/Desert and the E-231 equipped plane I am flying really works in the smooth consistant conditions at this hill so it would be nice to translate this performance to all conditions.


T.D.

[Bart Vaio]

E-231 looks real cool, i like it :) nice choice..