Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
September 21, 2017, 10:40:49 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: 1 ... 6 7 8 9 10 11 12 [13]   Go Down
Print
Author Topic: Bungee Launch 36" Gliders  (Read 17740 times)
0 Members and 1 Guest are viewing this topic.
Hepcat
Platinum Member
******

Kudos: 200
Offline Offline

United Kingdom United Kingdom

Posts: 1,654



Ignore
« Reply #300 on: September 07, 2017, 05:30:04 PM »

Response to #298.

Jon,
I was interested in your reference to EDA.  I did a lot of work on it at one time so, just keeping things simple for the moment, do you treat an even chord wing with square tips as an even chord wing with square tips or do you assume an elliptical lift distribution from tip to tip?
Hepcat John.
Logged
Yak 52
Titanium Member
*******

Kudos: 53
Offline Offline

United Kingdom United Kingdom

Posts: 2,151


Free Flight Vagrant



Ignore
« Reply #301 on: September 08, 2017, 06:38:32 AM »

I am following very closely this topic, trying to apply the lesson to E-36 which has the same span limit but a somewhat different speed envelope.

Jon, can you give us the 5 wing cords for your Ellipse 36 wing other than the root cord of 6,75"? And the length of the single panels.

I would like to play/use with XFLR5, but did not have the courage to open it till today  Sad  How about a tutorial on a new topic???

Urs

Urs,

Attached is a first attempt at a 5 panel wing at A=6. This is not yet optimised in XFLR5 in any way but it does 'perform' better that the A=6 constant chord wing on sink rate. It's drawn in metric but chords are essentially 7" root, 6" mid and 4" tip. Rib centres at 47mm (near enough 1 and 7/8".)

When you mention the different envelope for E36 are you talking about a faster climb? In that case I think there would be potential benefit in a more elliptical planform.

Happy to attempt an XFLR5 thread if theres some interest... must admit I'm just learning it myself too though!


Response to #298.

Jon,
I was interested in your reference to EDA.  I did a lot of work on it at one time so, just keeping things simple for the moment, do you treat an even chord wing with square tips as an even chord wing with square tips or do you assume an elliptical lift distribution from tip to tip?
Hepcat John.

John, I did a bit of research on the methods a few years ago but these days I just use one of two calculators:

Martin Brungard's found here: http://www.charlesriverrc.org/articles_modeldesign.htm

And the one in Curtis Suter's 'Sailplane Calc' here: http://tailwindgliders.com/Files.html

They come up with slightly different answers. If I recall correctly the Brungard one takes account of panel areas but the Suter file assumes an elliptical lift distribution.


Jon
Attached files Thumbnail(s):
Re: Bungee Launch 36" Gliders
Logged
USch
Gold Member
*****

Kudos: 16
Offline Offline

Italy Italy

Posts: 858




Ignore
« Reply #302 on: September 08, 2017, 01:51:08 PM »

When you mention the different envelope for E36 are you talking about a faster climb?

Jon, exactly. The best E36 go to 180m height in 10 seconds, not my ones (yet). Assuming a spiral climb gives about 240-250m to travel, so actual climb speed would be around the 25m/sec mark.

Urs
Logged

Fast up-Slow down
Pages: 1 ... 6 7 8 9 10 11 12 [13]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!