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Author Topic: Tern Free, composite TLG  (Read 11166 times)
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dylan1024
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« Reply #100 on: August 31, 2015, 02:44:10 PM »

Latest wing out of the molds. Just under 44grams
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OZPAF
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« Reply #101 on: August 31, 2015, 09:03:48 PM »

Nice work.

John
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randoloid
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« Reply #102 on: December 02, 2015, 10:47:46 AM »

That is absolutely beautiful!
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Geneulm
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« Reply #103 on: December 02, 2015, 11:03:17 AM »

Stunning. 
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dylan1024
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« Reply #104 on: February 20, 2020, 05:59:42 PM »

Hi everyone

After a long time, I am slowly getting another Tern ready to fly. I am piecing together a model that will hopefully be a test bed for future ideas. it will probably be a tad heavy.

specs:
Using the first wing we ever molded
Pop up boom DT (trying to get the tail lighter)
shorter nose
shallower fus
lighter boom (Easton Carbone one 2000 spine arrow shaft)
crusiform tail to start off with


some notes:
The big change here is the fuselage... the  previous Tern had a lot of side area up front and Blake and myself believe it was hindering the transition as well as windy weather performance. Having not decided on an exact remedy, i cut up and old fus and will be piecing it back together....this includes pop up boom.

the wings had warped with time, we learnt how to fix this with mirror image fabric, but like i said, this was wing set number 1...So..... i baked them Grin and then jigged them up and so far it seems to be ok.

the boom is obviously more flexible but the weight savings is worth it... if all this proves worthwhile... we'll look into a fuselage mold and make good, rigid and light fuselages.


and the bit thats got me busy at the moment: airfoiled cruciform tail set...

I know this is controversial, but im stubborn and maybe stupid, but i believe it is the way to go and that it would result in far more efficient launches.
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dylan1024
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« Reply #105 on: February 20, 2020, 06:01:01 PM »

some more photos
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OZPAF
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« Reply #106 on: February 20, 2020, 07:30:51 PM »

Good to see that this is still being developed. Increased polyhedral as well.

thanks for the update and good luck with the development.

John
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ptlove
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« Reply #107 on: February 21, 2020, 02:21:12 AM »

Dylan and Blake, stellar work and craftsmanship!

It's inspiring to see innovative ideas and passion for experimentation with TLGs.   I remember lurking many times on this thread 5 years ago and it's great to see it come to life again.  Your project and the work of a few others who've gone down the composite/carbon road with TLGs inspired me to do some designing and building last year as well.  Since you mention in your post above that you will try a cruciform tail this time, which you've correctly pointed out to be controversial, I can share my findings in case you find it interesting, encouraging, or discouraging.  The design in the pic below was somewhat inspired by RC DLGs (which we all know launch much higher than our free flight TLGs).  The intent was to optimize launch height at the intentional expense of some other usually desirable attributes, and a cruciform tail was part of that equation. 

After much testing, tweaking, measuring altitude with an altimeter and yaw with slow motion video (https://www.youtube.com/watch?v=_fMTeWjxgXY), and scratching my head again and again, I believe the jury is still out on this topic as far as launch altitude is concerned, so I am excited to see you have decided to try cruciform.  For both this carbon winged V dihedral glider, and a more traditional balsa winged polyhedral TLG, I built both a Y tail and cruciform tail boom for each so I could swap them back and forth easily during the same flying session, and try to measure the differences in peak altitude and initial yaw just after the moment of release.  My altitude with the cruciform and the Y tail were about the same.  However, I must point out that for outdoor flying the Y tail behaves better in the glide while circling in that it seems less prone to spin in when upset (i believe due to less vertical area), it seems to create a more reactive glider, and I think it has a slight advantage in transitions (minimum loss of altitude).  At this point if i were designing to maximize my results in a competition, I'd have to go with the Y tail, but I fly for lots of reasons, and in fact 95% of my flying is for fun and experimentation...and the cruciform tail is fun to experiment with and it looks cool too IMO Smiley 

My experiments are far from complete.  I have a long list of refinements and design experiments I plan to test in the quest for more altitude without sacrificing too much on other important attributes, but it will be years before they are complete.  I'm sure you have a similar list. Its not easy to add something of true value to the design pool in this hobby considering that there are some real geniuses out there with probably thousands of hours of flying time.  Good luck with your Tern Free, and have fun!   I look forward to watching your progress.

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Ployd
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« Reply #108 on: February 29, 2020, 11:14:45 PM »

Dylan and Blake, great to see you are still experimenting and will watch your progress with interest.

My new models now feature a tip up wing which keeps the fuselage construction simple and model can break down into 2 pieces for transportation. I did note the use of tail tilt on your previous model and this is also favoured by a number of Japanese models, videos posted on Facebook and incorporated in to my models.

Ployd in OZ.
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dylan1024
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« Reply #109 on: March 08, 2020, 05:21:57 AM »

Some progress:
Cruciform tail is an experiment as well as delta fin planform in attempt to stop the fin stalling during launch. We'll see what happens.

The stab has a Drela HT22 foil. The fin uses a Z4D foil from Gerald Taylor

Fin and stab weigh 4.8g, a tad heavy but I am happy for now.

Timer is my own muscle wire host timer/actuator paired with a Leo Bodnar RDT.

All that's left is to cast the urethane nosecone/nose weight.... Looks like AUW will be about 95 to 100g
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OZPAF
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« Reply #110 on: March 09, 2020, 04:47:02 AM »

Interesting and looking tail Dylan. Have you had problems with the fin stalling?

The detail design is very neat. I noticed that you have managed to hide largely the DT rubber band.

Good luck with this version.

John
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dylan1024
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« Reply #111 on: March 09, 2020, 04:36:38 PM »

I can't say we have had problems with the fin stalling, but its a hunch. I don't think the flat plate tails behave well at high alfa during launch.

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OZPAF
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« Reply #112 on: March 09, 2020, 07:00:36 PM »

Thanks -if you're correct - then it should give you more launch height.

John
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