Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
November 21, 2018, 05:54:46 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] 2 3 4 5   Go Down
Print
Author Topic: Tern Free, composite TLG  (Read 8842 times)
0 Members and 1 Guest are viewing this topic.
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« on: September 08, 2014, 01:57:08 AM »

Hi everyone

after building two Tern II's, a 1990's Larry Conover design, my friend Blake and myself became hooked on freeflight gliders.

with Blake being an avid F3k modeller it was decided that our next venture would be a TLG.

All composite. Solid core, molded wings(molds still to come). and a full composite fuselage.

36" wingspan.
Attached files Thumbnail(s):
Tern Free, composite TLG
Tern Free, composite TLG
Tern Free, composite TLG
Tern Free, composite TLG
Logged
Ployd
Gold Member
*****

Kudos: 19
Offline Offline

Australia Australia

Posts: 297




Ignore
« Reply #1 on: September 08, 2014, 04:09:55 AM »

I like what I am seeing but can I ask a dumb question...how are you going to DT it?

Ployd in OZ
Logged

"So I collect engines, what's your problem?"
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #2 on: September 08, 2014, 04:48:14 AM »

Hi Ployd,

After hours of deliberation we decided to stray from the break boom DT.
We are going to risk an attempt at spoilers on one model and a pop up stab on the other; this is to keep the DT internal, we just wanted to try something cleaner and sleeker.
If these methods dont work, the option is still there to cut the back of fuse pod off and install plywood bits for traditional break boom DT.

Dylan & Blake



Logged
PeeTee
Titanium Member
*******

Kudos: 48
Offline Offline

United Kingdom United Kingdom

Posts: 2,214



Ignore
« Reply #3 on: September 08, 2014, 05:28:02 AM »

Why not go for a pop up wing, it'll mean the least modification?
Logged
Monique
Guest

« Reply #4 on: September 08, 2014, 05:59:28 AM »

Howzit Dylan, that's a lekker looking glider!

Have you seen these little viscous dampers used as DT timers? https://www.youtube.com/watch?v=OE9Fm_KgRQY
Logged
Tapio Linkosalo
Platinum Member
******

Kudos: 28
Offline Offline

Finland Finland

Posts: 1,140



Ignore
« Reply #5 on: September 08, 2014, 06:16:11 AM »


As you are going for a molded wing (and a CNC mold I suppose), why not elliptical dihedral?

Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #6 on: September 08, 2014, 06:32:10 AM »

Hi All

Pop up wing is an option  Grin.

we are going to use a viscous timer, we sourced some from Freeflight Supplies.

Re. the dihedral: we are pretty new to this game and have seen all sorts of designs. molding flat wings allows us to play with the dihedral easily without having to manufacture new molds each time. multiple polyhedral breaks should get us close to the same performance as elliptical but also allows us to try asymmetric dihedral.

airfoil is as close to a StanBEmod2 as we could get. molds will be cnc machined alluminium.

Dylan & Blake
Logged
Monique
Guest

« Reply #7 on: September 08, 2014, 06:43:00 AM »

The dampers are cool, I've gotten two minutes consistently with one, it all comes down to the strength of the rekkie or spring to pull it.
Logged
Ployd
Gold Member
*****

Kudos: 19
Offline Offline

Australia Australia

Posts: 297




Ignore
« Reply #8 on: September 08, 2014, 06:59:55 PM »

While not an all composite build, your design is very close to what I have already. Are you going to use a wing tip peg or "pen grip" method for launching?

Ployd in OZ
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Logged

"So I collect engines, what's your problem?"
Tapio Linkosalo
Platinum Member
******

Kudos: 28
Offline Offline

Finland Finland

Posts: 1,140



Ignore
« Reply #9 on: September 09, 2014, 12:22:06 AM »

Re. the dihedral: we are pretty new to this game and have seen all sorts of designs. molding flat wings allows us to play with the dihedral easily without having to manufacture new molds each time. multiple polyhedral breaks should get us close to the same performance as elliptical but also allows us to try asymmetric dihedral.

How about making two elliptical wing halves, and adjusting the total dihedral with the amount of DH in the centre joint?
Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #10 on: September 09, 2014, 02:48:10 AM »

Ployd,

We love the lines of the Morris dancer. it was part of our inspiration.

Tapio,

That would only work for symmetrical dihedral. if that process was followed for asymmetric. then the effective result would be lots of stab tilt.... I think.

Also that makes the molds very expensive as large amounts of material are needed or complex plate rolling prior to machining.

Dylan & Blake
Logged
Ployd
Gold Member
*****

Kudos: 19
Offline Offline

Australia Australia

Posts: 297




Ignore
« Reply #11 on: September 09, 2014, 04:18:24 AM »

Quote
We are going to risk an attempt at spoilers on one model


At the risk of being branded as a nay sayer I have my doubts about spoilers being effective as while there is no forward motion a thermal of enough power will still carry it away because you are still presenting two flat surfaces for the thermal to act on. With a tip up tail or broken back DT you not only remove a stabilizing surface but forces the model to rock from side to side like a leaf which breaks the thermal's hold. Still, I am happy to be proved wrong but it seems an awful lot of mechanical skull duggery to pop up spoilers.

Thanks for the compliment, the model looks better that the West Coast "cow horns".

For dihedral try 12mm for the first break and 25mm to the two outer panels. Oh, and the span of the model in the picture is 39" (gnat's whisker under one metre).

Ployd in OZ
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Logged

"So I collect engines, what's your problem?"
Hepcat
Platinum Member
******

Kudos: 276
Offline Offline

United Kingdom United Kingdom

Posts: 1,777



Ignore
« Reply #12 on: September 09, 2014, 12:25:46 PM »

Tapio et al,
I think the first time I saw mention of Elliptical dihedral was in Ron Warring's 'Model Gliders' published in 1942 and have been reading about it ever since.  It looks as if it should be the correct thing to do but I have never seen any proof of its superiority nor any suggestion of the asymmetry of the ellipse to be used or the portion of the ellipse to be used.  I appreciate that there should be a gain by not having the drag of dihedral breaks.  Of course if one cheats by approximating some sort of ellipse with multiple straight panels then the dihedral break drag will increase.increases the number of breaks.  Perhaps a straight dihedral wing with only one break disguised by the fuselage is the way to go.<smile>

Comments would be welcome.

John
Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #13 on: September 16, 2014, 03:04:17 PM »

Top surface of the mold is done. Bottom surface on the machine. Ployd.. after your last message we squeezed as much span as we could fit in the plate. 510mm for each half.
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Logged
sweepettelee
Platinum Member
******

Kudos: 19
Offline Offline

United States United States

Posts: 1,311


Simplicate & add more lightness. Keep sanding!



Ignore
« Reply #14 on: September 16, 2014, 03:55:26 PM »

Re asymmetrical planforms, there is a flight video(U Tube I think) of a Japanese FF TLG which has lots of right tilt.
This appears to me to be due to the wing dihedral layout: left wing has one break about 3" from tip, whilst right wing
has two breaks, plus more overall d'dral. Hence, the need for more right tilt to compensate. The launch & recovery 
are among the best I have ever seen, with no obvious wiggle-waggle of boom & Y-tail group.
This fact alone seemed to result in a high & nearly straight left climb, with clean recovery.
Maybe a search would allow the astute online users to see what I mean.
A link or info on the Nippon flyer would be most appreciated...
Logged

Leeper
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #15 on: September 21, 2014, 04:01:14 AM »

Some progress pics
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #16 on: September 21, 2014, 11:15:54 AM »

57.8g

Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #17 on: September 25, 2014, 05:26:53 AM »

Second time round went better weight wise. Happy with the results
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Logged
OZPAF
Palladium Member
********

Kudos: 163
Offline Offline

Australia Australia

Posts: 4,428



Ignore
« Reply #18 on: September 25, 2014, 06:20:36 AM »

Thats very very nice work Dylan. I didn't notice a shear web for the carbon caps of the spar - are you using one? Also are you using a EPS foam core - this would enable a very light shgear web of even glass to be used. The difference in bending strength would be significant and far outweigh any extra weight incurred.
John
Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #19 on: September 25, 2014, 07:06:52 AM »

Hi John,

The wings are molded solid core using rohacel 31 and the lightest carbon available from Vlad. Russian UD from freeflight supplies as spar caps and a double shear web of 20g glass cloth on the bias. wings are very rigid.
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Logged
OZPAF
Palladium Member
********

Kudos: 163
Offline Offline

Australia Australia

Posts: 4,428



Ignore
« Reply #20 on: September 26, 2014, 03:42:51 AM »

Nicely done Dylan. I can imagine how stiff the wings are - you should be able to winch launch that wing Cheesy

Good luck with it.
John
Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #21 on: October 02, 2014, 10:27:14 AM »

Little more progress.
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Re: Tern Free, composite TLG
Logged
dylan1024
Bronze Member
***

Kudos: 2
Offline Offline

South Africa South Africa

Posts: 34

Topic starter


Ignore
« Reply #22 on: October 02, 2014, 10:32:49 AM »

Tail feathers test
Attached files Thumbnail(s):
Re: Tern Free, composite TLG
Logged
Ployd
Gold Member
*****

Kudos: 19
Offline Offline

Australia Australia

Posts: 297




Ignore
« Reply #23 on: October 02, 2014, 06:28:14 PM »

WOW!! I want one  Tongue

I noticed your timer set up but feel the model screams for an electronic r/c DT system then it will be a true 21st century creation.

On the tail feathers can I suggest that you add a 0.6mm x 1mm basswood strip to the LE of the tail plane (which extends around the tips as well) and LE of the fin. Aim for a finished weight of no more than 4 grams for the fin and stab. Oh, forgot to ask, what moment arm dimension are you using?

Ployd in OZ
Logged

"So I collect engines, what's your problem?"
Oldtime Flyer
Gold Member
*****

Kudos: 10
Offline Offline

United States United States

Posts: 335


"Keep it Simple"



Ignore
« Reply #24 on: October 03, 2014, 12:23:16 AM »

One word comes to my mind when looking at this TLG design,

              "WICKED"


OTF'er
Logged
Pages: [1] 2 3 4 5   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!