SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
This thread is privately moderated by Hobster, who may elect to delete unwanted replies.
Old Mar 20, 2011, 04:10 PM
He who dares ... repairs!
Hobster's Avatar
Joined Jun 2005
682 Posts
Discussion
MH32 better for DS than RG14??

Question: Would my Mini Graphite wing (with MH32 aerofoil section) be better suited to high speed DS (300mph+) than my Opus MCT (RG14 section) - ignoring for now strength!

XFLR5 suggests MH32 is lower drag than the RG14 at Re 2.0e+06 to Re 3.0e+06 at Mach 0.4 to 0.5. Or am I using XFLR5 to far outside its design remit - computational assumptions being stretched too far etc?

Images show plots for up to 4 aerofoil sections: MH32 (as used on Mini Graphite), RG14 (Opus MCT), JM26 (Dynamic 80), RK40 (Dynamic 60). Graphs show MH32 lower Cd than RG14 and RK40.. but higher than JM26.
Hobster is online now Find More Posts by Hobster
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 20, 2011, 05:58 PM
Where is the inspiration
wdeighton's Avatar
Moira
Joined Feb 2006
825 Posts
Thats all quite cool but I dont realy understand it that much.
The Alfa that is mentioned, it that if the wing is at high alfa? Because a ds wing is more often at high alfa.

Is it possible to change this and then re simulate? It may become apparent that some sections are better at larger radii and others better at small radii.

What section is on the Mini Dragon? I thought that was an RG14, but so far its not been as quick as the opus, Just doesn't have the same acceleration. And what thickness are you working with because that changes things too.

Steve, do these graphs make sense to you? If yes I would like to have a chat over the program and try get a better understanding.
Be interesting to draw around the kinetic section to add to your selection.
wdeighton is offline Find More Posts by wdeighton
Reply With Quote
Old Mar 20, 2011, 06:18 PM
He who dares ... repairs!
Hobster's Avatar
Joined Jun 2005
682 Posts
Hi Will,

I ran the calculations up to 3 deg alpha.

Reading off the alpha/Cl graph, and taking, for example 2degs alpha, this equates to a Cl of 0.45 to 0.6 (depending on the section).

Reading off the Cd/Cl graph, this suggests at 2degs Jm26 has Cd of ~0.4, MH32 ~0.48, RG14 ~0.6

Yes, both Opus and MD are supposed to be RG14 - though sections often quoted as 'modified' whatever that means. I think the MD wing is thinner than the Opus's approx 9%.

The Kinetic section isn't available - at least I've not seen it published.

Steve
Hobster is online now Find More Posts by Hobster
Reply With Quote
Reply

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Anything comparatively better than PolyQuest XQ 11.1V 3200ma battery for less? bigo66 Batteries and Chargers 1 Jan 04, 2011 11:51 PM
Discussion Is there cheaper/better heli than MCX for beginner indoor??? duganderson Micro Helis 6 Dec 06, 2010 02:34 PM
Discussion Better than DS. Dynamic Gliding John Kim Dynamic Soaring 6 Feb 07, 2008 03:59 PM
Mini-HowTo EZ* Set-up...Watching is better than seeing which is better than reading... scrtsqrl FPV Talk 15 Aug 27, 2007 11:11 PM
RG14 or RG15 for 2m DS plane? alkoo Dynamic Soaring 55 Sep 29, 2005 07:33 PM