Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
January 23, 2018, 04:42:43 AM *
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 19516 times)
0 Members and 1 Guest are viewing this topic.
Hepcat
Platinum Member
******

Kudos: 209
Offline Offline

United Kingdom United Kingdom

Posts: 1,696



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: 54
Offline Offline

United Kingdom United Kingdom

Posts: 2,199


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: 19
Offline Offline

Italy Italy

Posts: 896




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
Haoyang Wang
Bronze Member
***

Kudos: 0
Offline Offline

United States United States

Posts: 10



Ignore
« Reply #303 on: December 12, 2017, 03:00:15 AM »

How strong should the tow hook mounting point be, to keep the tow hook from being ripped off the glider? A piece of balsa? Reinforced with fiberglass cloth? A piece of basswood? Plywood?

Most plans only have the tow hook position marked out, but not the specifics of the mount.

Thanks!
Logged
FLYBOY49
Bronze Member
***

Kudos: 2
Offline Offline

United States United States

Posts: 51



Ignore
« Reply #304 on: December 12, 2017, 09:31:26 AM »

My FROG WREN has the hook inserted in just regular balsa.  Seems to work O.K.

However, it does penetrate the keel piece and wrap over the top of it.

Remember that the bungee is only a 1/8th" piece of rubber. Not much strain to it.

It goes up so stately that I love it.

Gotta build some more designs soon.  Like a LU LU, Gnome, etc.  Kinda wish i could include a WALKING SHOES like Jim has.  Maybe some day. But, 1st I'm building a THERMIC 'C by JASCO. I already have the JETCO model of the 'C'. I'm kinda stuck on building just LASER CUT models except for this one model 'C' which is taking forever.

Might sideline it to get started on something faster to build.

A while back I got a DRIFTY kit for a much smaller glider and had it enlarged to 36" W.S.  Have it framed up, ready to cover.  GottA 'GET 'ER DONE'.

 Van...
Logged
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!