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Outdoor Free Flight Forum => Tip Launched Gliders => Topic started by: dylan1024 on September 08, 2014, 01:57:08 AM



Title: Tern Free, composite TLG
Post by: dylan1024 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.


Title: Re: Tern Free, composite TLG
Post by: Ployd 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


Title: Re: Tern Free, composite TLG
Post by: dylan1024 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





Title: Re: Tern Free, composite TLG
Post by: PeeTee on September 08, 2014, 05:28:02 AM
Why not go for a pop up wing, it'll mean the least modification?


Title: Re: Tern Free, composite TLG
Post by: Monique 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 (https://www.youtube.com/watch?v=OE9Fm_KgRQY)


Title: Re: Tern Free, composite TLG
Post by: Tapio Linkosalo 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?



Title: Re: Tern Free, composite TLG
Post by: dylan1024 on September 08, 2014, 06:32:10 AM
Hi All

Pop up wing is an option  ;D.

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


Title: Re: Tern Free, composite TLG
Post by: Monique 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.


Title: Re: Tern Free, composite TLG
Post by: Ployd 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


Title: Re: Tern Free, composite TLG
Post by: Tapio Linkosalo 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?


Title: Re: Tern Free, composite TLG
Post by: dylan1024 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


Title: Re: Tern Free, composite TLG
Post by: Ployd 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


Title: Re: Tern Free, composite TLG
Post by: Hepcat 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


Title: Re: Tern Free, composite TLG
Post by: dylan1024 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.


Title: Re: Tern Free, composite TLG
Post by: sweepettelee 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...


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on September 21, 2014, 04:01:14 AM
Some progress pics


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on September 21, 2014, 11:15:54 AM
57.8g



Title: Re: Tern Free, composite TLG
Post by: dylan1024 on September 25, 2014, 05:26:53 AM
Second time round went better weight wise. Happy with the results


Title: Re: Tern Free, composite TLG
Post by: OZPAF 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


Title: Re: Tern Free, composite TLG
Post by: dylan1024 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.


Title: Re: Tern Free, composite TLG
Post by: OZPAF 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 :D

Good luck with it.
John


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on October 02, 2014, 10:27:14 AM
Little more progress.


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on October 02, 2014, 10:32:49 AM
Tail feathers test


Title: Re: Tern Free, composite TLG
Post by: Ployd on October 02, 2014, 06:28:14 PM
WOW!! I want one  :P

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


Title: Re: Tern Free, composite TLG
Post by: Oldtime Flyer on October 03, 2014, 12:23:16 AM
One word comes to my mind when looking at this TLG design,

              "WICKED"


OTF'er


Title: Re: Tern Free, composite TLG
Post by: OZPAF on October 06, 2014, 03:22:18 AM
Very interesting - I can't wait to see this thing fly.
John


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on October 07, 2014, 03:58:41 PM
Ployd6

In an attempt to save weight we decided to face the LE with a 25g/m□ fiberglass strip. The stab and fin came out at 3.4g  ;)


As for moment dimensions, not 100% sure, we going with trial and error . Our starting point= nose to wing LE 187mm Chord is 124mm and 470mm from wing TE to stab LE.

Blake


Title: Re: Tern Free, composite TLG
Post by: Ployd on October 07, 2014, 05:20:21 PM
Thanks Blake, looking good. Nose length is on the money but would suggest reducing the moment arm down to 410mm (16.15").

Ployd in OZ


Title: Re: Tern Free, composite TLG
Post by: sweepettelee on October 07, 2014, 07:34:03 PM
Blake,

I respectfully disagree with my good buddy Ployd re TMA.
I suggest you leave it long at your dimension of 470 mm.
Reasons are:
1. Most 1 meter TLGs in USA seem to be over 18 TMA, with Spin F1N of Stan B & Tim B 18.5 to 18.63, wing TE to stab LE. (~470-473-mm)
2. If you decide during flight testing that boom is too long(maybe transition or gust recovery from stalls is not to your liking), then it should be easy
to shorten the boom.  That is the best solution, since adding material makes fixes difficult to say the least...Big OOPS! :o

Leeper, aka Sweepettelee  ;D


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on October 10, 2014, 07:07:41 AM
Dylan and I are ready for first flight tests this wknd. The test model has come out at 103g balanced and ready to fly. We should be able to get to 90g on the next one but durability will be the determining factor.

Regarding moment arm/boom length, would you guys mind elaborating on what to expect in the transition and or gust recovery phase when the moment arm is to long or to short? Im sure there will be tradeoffs here but I have no clue what they are.

Blake


Title: Re: Tern Free, composite TLG
Post by: Ployd on October 10, 2014, 07:08:41 PM
Hi Blake

Leeper and I will respectively agree to dis-agree on the moment arm question but my take is simple and it is tied into the physical dimensions of the boom you are using for the fuselage (and there is a difference between indoor and outdoor use).

I use an Avia sports graphite kite boom (8mm down to 6mm diameter for a 32" (813mm) length) and initially I started with a MA of 17.5" (445mm) which does give an arrow straight climb in calm conditions but in gusty or turbulent conditions boom flex caused me problems during launch so I did a trade-off and reduced the MA to 410mm to reduce the flex. The climb and glide were un-affected. Ideally a larger diameter boom would be the way to go, say, 10mm down to 6mm (which if I remember correctly is what Mark Benn's used).

I would be interested to know what our American cousins are using.

Ployd in OZ


Title: Re: Tern Free, composite TLG
Post by: -John- on October 11, 2014, 10:09:37 AM
From the photo of the V-tail portion of the Y-tail group on reply #22 it looks like the tail plane area is not extremely large, so maybe it would be Ok to start out with a somewhat longer tail moment. The photo(s) of Ployds model(nice looking TLG by the way) make the V-tail look somewhat large(?).

Do you have the plans for Mark Benns Spin Up 42?


Title: Re: Tern Free, composite TLG
Post by: julio on October 11, 2014, 12:28:19 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...

Sorry to be late Sweepettelee. The flyer is Mitsuru ISHII (Japan). There is plenty of info, videos and plans at the following link.

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=2669.msg22347#msg22347

'2 panels on one side of the wing and 3 on the other...'

Julio


Title: Re: Tern Free, composite TLG
Post by: julio on October 11, 2014, 05:54:50 PM
I think I rushed to post the above reply...It refers to an indoor free flight TLG, but it was so close to the description posted by Sweepettelee (asymmetric dihedral, japanese model and flyer) that I didn't realized this thread was at the outdoor free flight forum. My apologies.

Julio


Title: Re: Tern Free, composite TLG
Post by: sweepettelee on October 11, 2014, 08:35:15 PM
Ah yes, that is correct. Ishii's video was indoor.


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on October 12, 2014, 03:12:56 AM
Ployd

Thanks for your reply. It makes sense. Dylan n I will be doing a one piece fuselage and boom to increase rigidity at some stage. It will be done in such a way that we can layup boom only as well. Elliptical in section and tapered. Maybe we should start composite fuse/boom builders lounge?

John

I have the spin up 1000 plan. Not sure if the spin up 42 is the same thing?


Title: Re: Tern Free, composite TLG
Post by: Ployd on October 12, 2014, 11:59:31 PM
Hi Blake

A one piece fuselage will only work if the mode of DT is effective and sofar a tip-up boom has been the most effective method to date and easy to engineer.

An elliptical boom is an interesting approach but think that a tear drop cross section maybe better. It is lateral bending of the boom during launch that has to be minimized not longtitudinal.

Ployd in OZ


Title: Re: Tern Free, composite TLG
Post by: -John- on October 24, 2014, 10:54:43 PM
John

I have the spin up 1000 plan. Not sure if the spin up 42 is the same thing?
Blake, ...not sure if the 42 plan is the same as the 1000, but it seems logical as the 42 builds up to an essentially 1 meter glider.

Have you had any maiden flights?

...also, Ployd makes good point about the pop-up tail boom as the contemporary means of D/T, and it also allows for effective and easy incidence adjustment on the field.


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on November 10, 2014, 11:03:45 PM
We had some good weather yesterday and put in some flights. ... we think the declage was a bit much after some repairs. Also the launch tip side is a lot heavier than the other tip.  Will post again after we get another session in

Watch "Ternfree launch2" on YouTube - Ternfree launch2: http://youtu.be/tp_pwC5kJX4

Watch "Ternfree launch" on YouTube - Ternfree launch: http://youtu.be/zCPqxqswhX8


Title: Re: Tern Free, composite TLG
Post by: Rewinged on November 11, 2014, 12:13:04 AM
Glider videos look great--should be fantastic with final launch trim and good recoveries, since the glide looks great!

Re launch tip heavier--some of this is OK, even helpful, since it aids thermal-seeking by offsetting the turn from the rudder/skew.

--Bill


Title: Re: Tern Free, composite TLG
Post by: dosco on November 11, 2014, 07:17:34 AM
An elliptical boom is an interesting approach but think that a tear drop cross section maybe better. It is lateral bending of the boom during launch that has to be minimized not longtitudinal.

Ployd:
If the major axis of the ellipse is aligned with the lateral plane, the stiffness will be maximized for TLG launch. I think some of the RC DLG guys who are fabricating 1-piece composite fuselages are doing this ... I've lost track as I haven't been following RC DLG in the last year or so.

-Dave


Title: Re: Tern Free, composite TLG
Post by: boca55 on November 11, 2014, 08:30:28 AM
The model is excellent. I get the impression that he could do more to climb. There should be only slightly reduce the difference of angles. Transition will be much better.


Title: Re: Tern Free, composite TLG
Post by: MarkCovington on November 11, 2014, 10:13:27 AM
 How much skew do you have in the V-tail?

 Mark C


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on November 11, 2014, 10:38:39 AM
Zero stab tilt and zero skew.

We cant find a decent illustrated explanation of tilt and skew and their corresponding directions... so we left it zero zero


Title: Re: Tern Free, composite TLG
Post by: MarkCovington on November 11, 2014, 04:08:33 PM
 L.E. of stab at centerline should be about 1/16 (1.5mm) left of T.E. at centerline. No stab tilt needed. That change would make launches and transitions much better. Looks pretty good as is.
If you don`t want to add the skew, try some tip weight on the right side. This is just my opinion though.

 Mark C


Title: Re: Tern Free, composite TLG
Post by: Ployd on November 11, 2014, 04:58:49 PM
Like the videos and the model makes a definite whistle on launch  :)

I do not use either stab tilt or skew on any of my models and have found no reason to use it. When the Morris Dancer was designed way back on the SFA forum (2006) stab skew was unknown until the first kits were seen in OZ but by then it had become common knowledge in the US and has appeared on all subsequent published and kitted designs.

As regard to one wing tip heavier than the other, I statically balance the wing by adding lead to the opposite tip (built in) then add an additional piece of lead to the tip to make it slightly heavier (right hand circle, right hand tip) then file away that lead piece until there is just enough weight to drop the inboard wing into the glide...gets rid of the stall as it transitions into glide mode. Sometimes a bit of rudder tweaking is required.

Quote
If the major axis of the ellipse is aligned with the lateral plane, the stiffness will be maximized for TLG launch

Agree with you on this thinking but on a F/F TLG it means making a wider nose pod so that a "broken back" DT can be fitted.

Ployd in OZ


Title: Re: Tern Free, composite TLG
Post by: OZPAF on November 11, 2014, 05:33:15 PM
Thats a nice glide Dylan. I have no experienc with TLG but a bit with CLG and I suspect i would be trying a bit of built in right rudder and tail tilt for the glide.
It certainly has potential.
John


Title: Re: Tern Free, composite TLG
Post by: dosco on November 12, 2014, 07:45:47 AM
If the major axis of the ellipse is aligned with the lateral plane, the stiffness will be maximized for TLG launch

Agree with you on this thinking but on a F/F TLG it means making a wider nose pod so that a "broken back" DT can be fitted.[/quote]

Ployd:
Apologies if my previous post was impertinent ... of course you're aware of this. I think the problem was with how I interpreted what you meant by "teardrop" ... I think I get it now.

Warm Regards-
Dave


Title: Re: Tern Free, composite TLG
Post by: USch on January 13, 2015, 05:37:39 PM
Hi Dylan and John,
that's a real fantastic piece of work, my warmest compliments.
Just some question, how do you prepare the rohacell core? I tried cutting with hot wire, no chance, so I had to sand it. Do you mill it ???
Secondly, probably you heat the mould slightly (40-50°C) during curing. We had a lot of trouble because of the different thermal expansion coefficient of aluminum against a carbon structure with near to 0 coefficient. How do you tackle this matter?
A warning about russian carbon, it has the same stiffness but only half the tensile strenght in comparison to "our" western carbon. Actually I thing the two spar caps would benefit from beeing made from high modulus UD fibre.

That's just my 2 pence worth.....

Urs


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on January 15, 2015, 01:35:45 PM
Hi Urs

We mill the rohacell.
So far the expansion issue has not proven to be a problem.

We play with all sorts of carbon. The Russian is HM as far as i know.


Thanks for the kind words


Title: Re: Tern Free, composite TLG
Post by: BG on January 15, 2015, 02:16:51 PM
So Dylan, would you be willing to make one or two for sale? Basically send the flat wing panels and fuselage pod.

I am pretty sure some of us would buy a set of wings from you.
B


Title: Re: Tern Free, composite TLG
Post by: OZPAF on January 15, 2015, 05:34:48 PM
How is it going Dylan? Are you working on a MK2.
Happy New Year by the way.
John


Title: Re: Tern Free, composite TLG
Post by: ThomasLee on January 23, 2015, 06:46:58 PM
Really cool Dylan and Blake!
Just got a few guys interested in doing some TLG at the club, so we will be building a couple from kits or plans. After that, I would be so tempted to mold some for fun.... right up my alley  :D

Subscribed!


Title: Re: Tern Free, composite TLG
Post by: Ployd on January 24, 2015, 05:33:01 PM
Hello ThomasLee

Hope you appreciate that the Dylan/Blake model is for Free Flight and not r/c (two totally different design philosophies). If r/c is your thing then there are many ARF's and kits available, mainly from Eastern Europe.

Ployd in OZ


Title: Re: Tern Free, composite TLG
Post by: Randy Reynolds on January 24, 2015, 07:00:26 PM
Thomas is one of the leading designers and manufacturers of R/C DLG in Hong Kong and likely is well aware of the Eastern European vendors.  If he'll make some F/F composite "TLG"'s he'll have a good market at least in the US.


Title: Re: Tern Free, composite TLG
Post by: Maxout on January 25, 2015, 08:08:04 AM
We should also add that Thomas is an expert free flight modeler, and I believe his junior P-30 record still stands in Canada. BMJR sells one of his Embryo designs.

Thomas, would be great to see you do some more FF stuff. :)


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on January 26, 2015, 07:28:27 AM
Hi Everyone

Blake and I are still trying to get to the field for decent test flights. we are busy on other projects at the moment.

The Tern Free never started out as a commercial venture and after much debate between the two of us we would need to charge $280 for two wing halves and a fuse.

I have requested that a PDF of the plan be uploaded to this thread as well.

Dyl


Title: Re: Tern Free, composite TLG
Post by: Maxout on January 26, 2015, 07:48:14 AM
The Tern Free never started out as a commercial venture and after much debate between the two of us we would need to charge $280 for two wing halves and a fuse.

Outside my price range to be sure, but a very reasonable price for such an aircraft nevertheless.


Title: Re: Tern Free, composite TLG
Post by: BG on January 26, 2015, 01:09:57 PM
Sounds reasonable Dylan. I might buy one. I need to see that the DT situation is solved though. I am watching with keen interest.
B


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on January 27, 2015, 01:07:55 AM
link to the plan

 http://www.hippocketaeronautics.com/hpa_plans/details.php?image_id=7076  (http://www.hippocketaeronautics.com/hpa_plans/details.php?image_id=7076)



Title: Re: Tern Free, composite TLG
Post by: F3KBlake on January 27, 2015, 01:36:42 AM
Here's a pic of the latest version. 74g textreme carbon d/box, 25g glass skin and double shear web. AUW 90g. We scaled the tail up by about 5%. The fuse is way overkill on layup which is helping us though the learning stage because literally you cant break it. I must say the first tern we built survived some pretty insane crashes. Crashes you might ask. We tried crousiform tail which didn't work out so good.

80g Auw should be a walk in the park.

DT will be sorted in the near future. Dylan is pulling out all the stops on that project. Stay tuned.


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on January 27, 2015, 01:49:53 AM
 8)


Title: Re: Tern Free, composite TLG
Post by: ThomasLee on January 27, 2015, 02:04:56 AM
That is friggen sick! Will you have one with you in Croatia for us to oogle over?

Thomas - Team HK


Title: Re: Tern Free, composite TLG
Post by: ThomasLee on January 27, 2015, 02:09:43 AM
BTW, from the photo it looks as though you departed from polyhedral, is that correct? What is the reasoning?


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on January 27, 2015, 03:25:26 AM
Unfortunately Thomas im not going to Croatia, moneys a bit tight at the moment. Will definitely be at the next F3K Worlds. Would of been great tho. :-\
Yes there is only one dihedral break on this one. We did it to increase wing accuracy, much easier to build, lighter and also to see if we get better launch height. (Stiffer wing and less drag). Its got 12degrees dihedral.

Blake


Title: Re: Tern Free, composite TLG
Post by: BG on January 27, 2015, 09:52:48 AM
Blake,
2 questions: 1. how is the flight testing going? Looking at the plan it looks like you have a lot of rudder. Lee Hines once told me that you have to trim that rudder down to the minimum needed to ensure a good transition. Just a thought.
2. Have you had success with DTing reliably? What DT mechanism are you using?

Thx
Bernard (Ex pat South African).


Title: Re: Tern Free, composite TLG
Post by: Tmat on January 27, 2015, 11:30:35 AM
Just my 2 cents,
Your dihedral in both the poly version and Vee version looks to be too small. All of the successful FF TLG's I've seen have at least 18 deg Equivalent Dihedral Angle (EDA) and many are in the 19 to 20 deg EDA range. It's needed to transition correctly.

Beautiful work btw.
You will eventually come around to a pop-up boom or wing for DT.

Tmat
-everyone does eventually..... ;-)



Title: Re: Tern Free, composite TLG
Post by: Tmat on January 27, 2015, 11:33:19 AM
Btw,
I think the StanfoilBEmod2 is perhaps the best all around choice for a FF TLG airfoil. Brian Eggleston did develop several thicker airfoils with undercamber and semi symmetrical under surfaces and they were only a marginal or no improvement over the flat bottom Stanfoil.

Tmat




Title: Re: Tern Free, composite TLG
Post by: Ployd on January 28, 2015, 11:00:02 PM
Mr T, Oh contras.

While I cannot speak for Dylon's Vee dihedral version, the polyhedral version works just fine (watch the videos) and it was what I recommended back in Aug 2006 with the Discus Dancer (see attached) and have used ever since on subsequent versions.

I think what is becoming apparent is that there is more than one way to skin a cat and while acknowledging that the US designs work and are successful, the potential available projected wing area is constrained by the excessive dihedral needed for transition and dictated by the 3 break wing panel layout. Now that Dylon, Blake and Thomas Lee (all with F3K background) have discovered what we are up to expect some innovative ideas and a confirmation of the direction the new FF TLG's will head in.

Ployd in OZ


Title: Re: Tern Free, composite TLG
Post by: Tmat on January 29, 2015, 03:19:35 PM
Ployd,
I have not seen you launch. But I've seen Stan and the other top American TLG experts throw their birds. They need the dihedral they have to get a consistent transition. I think you need to witness those guys throwing to really get the idea. No offense, but your launch is probably half the height of Stan's. These guys can do nearly 2 minutes in dead air. If they thought that they could get away with less dihedral they would.

The only way I see around this would be to add a timer with auto surfaces that allowed a bunt transition. Then you could remove dihedral.
From my experience the old adage that dihedral is cheap always comes to mind. ;-)

Tmat


Title: Re: Tern Free, composite TLG
Post by: Rewinged on January 29, 2015, 04:21:44 PM
In most cases the U.S. flyers are not handicapped by dihedral limiting the projected span or area.  Most flyers are using models with span <=36 inches flat, so well below the 1 meter projected span.


Title: Re: Tern Free, composite TLG
Post by: Ployd on January 29, 2015, 05:49:51 PM
Matt,

I was referring to the videos posted by Dylon on page 2 of this topic ( I do not have any videos of my models being launched or in flight unfortunately) and the point being made in answer to your posting was that excessive dihedral, cheap though it maybe, was not the only way to go and that so-called "shallow poly dihedral" models will transition just as well when fully trimmed.
 
True, I may not get as high (altitude) as my American cousins but there is no substitute for square inches (or decimetres).

Ployd in OZ


Title: Re: Tern Free, composite TLG
Post by: danberry on January 29, 2015, 07:39:14 PM
There is absolutely NO substitute for altitude.


Title: Re: Tern Free, composite TLG
Post by: Rewinged on January 29, 2015, 11:25:30 PM
Obviously, both of the "no substitute" statements are correct at different times.  Sometimes the air is too weak down low but much better up a bit, and other times the air is just weak, and a great glide is needed.  Unfortunately, I don't get as high as many and my gliders don't glide as well as many.  But sometimes the air is good enough for me and my planes.


Title: Re: Tern Free, composite TLG
Post by: BG on January 30, 2015, 09:24:13 AM
Ployd, I guess the $0.65 question is; what are your dead air times like? This gives a direct measure of the relative effect of those extra square cm. There can't be that much of a difference in projected area with an increase in dihedral anyway.

B


Title: Re: Tern Free, composite TLG
Post by: Tmat on January 30, 2015, 09:31:44 AM
If two identical models have a 1 meter projected span, but different dihedral angles then the projected square inches are the same n'est pas?


Tmat


Title: Re: Tern Free, composite TLG
Post by: dosco on January 30, 2015, 12:47:01 PM
If two identical models have a 1 meter projected span, but different dihedral angles then the projected square inches are the same n'est pas?


Tmat

Is wing loading computed with actual square inches or projected square inches?

-Dave


Title: Re: Tern Free, composite TLG
Post by: Tmat on January 30, 2015, 01:13:23 PM
Projected IMO.
There is a case to be made that additional dihedral reduces the wing efficiency (extra drag from the dihedral breaks at higher angles, spanwise flow etc.). However, I'll say it again - dihedral is cheap.
But it's not an area issue.

Tmat


Title: Re: Tern Free, composite TLG
Post by: dosco on January 30, 2015, 02:15:15 PM
Projected IMO.

So then wing loading changes with bank angle(?).



Title: Re: Tern Free, composite TLG
Post by: Tmat on January 30, 2015, 03:42:19 PM
I suppose it does. Although it's not really of interest to me for Free Fight duration models.

Tmat


Title: Re: Tern Free, composite TLG
Post by: Tapio Linkosalo on January 30, 2015, 03:43:28 PM
It sure does. The tighter you trim a FF model to turn, the faster will be the sinking rate. And you do not need to go to extreme bank, but for - say - F1B, there is a difference when you open up the turn from 30sec per one turn in glide to 60sec per turn.


Title: Re: Tern Free, composite TLG
Post by: dosco on January 30, 2015, 04:53:49 PM
It sure does. The tighter you trim a FF model to turn, the faster will be the sinking rate. And you do not need to go to extreme bank, but for - say - F1B, there is a difference when you open up the turn from 30sec per one turn in glide to 60sec per turn.

I agree but in my experience that was due to the relationship of the lift vector to the frame of reference (or the "direction of gravity" so to speak).

We always treated wing loading as an invariant ratio of weight to wing area.



Title: Re: Tern Free, composite TLG
Post by: OZPAF on January 30, 2015, 05:27:57 PM
Thats the more correct way of looking at it Dosco. Wing loading should be calaculated on actual area and then allowance made for the angle of bank or dihedral and the corressponding loss of vertical lift, if necessary.

John


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on February 16, 2015, 03:18:36 AM
Some pics of the DT

Using nichrome to burn rubber band

 http://youtu.be/Q2xdANYN2_A


Title: Re: Tern Free, composite TLG
Post by: Tapio Linkosalo on February 16, 2015, 03:48:19 AM
What size of battery are you using? I tried to run mine on 20mAh, works OK in room temperature, but failed in freezer (winter simulation). Had to revert to 50mah battery (1g more weight)...



Title: Re: Tern Free, composite TLG
Post by: dylan1024 on February 16, 2015, 05:09:36 AM
Tapio

I am using a 30mah 25c...... must admit that i didnt think of low temp testing. We dont get tooo cold here in winter


Title: Re: Tern Free, composite TLG
Post by: jim_buxton on May 04, 2015, 03:41:43 PM
Very interesting thread!  I had pondered development of a DT system much like this, and we were getting help from one of the RC altimeter manufacturers.  Ultimately the project fizzled out as I decided to just go with an RDT unit.  This is a great looking option though.  Will the timer or parts (pod and wing panels) be commercially available? 
~Jim


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on May 07, 2015, 05:01:19 AM
Hi Jim

We are not sure if we will ever go into full production. we will look at making a few models to sell. we will keep you all up to date.



some progress for you all...

After some good advice from -John- here on the forum, we changed to a four panel wing with way more dihedral than we previously had. The effect of this was a far less critical model in terms of launch but it was still hit and miss with transitions. We cut the fin area down to the point that transitions were consistent and far less critical on wind direction.

We are using a pop stab DT but have yet to evaluate its performance in a big thermal. the stab has 9 degrees of left tilt.(left tip down).

here are some videos. conditions were not the best.

Launch and short DT: https://youtu.be/IgXvW_CQmIA (https://youtu.be/IgXvW_CQmIA)

Blake launching with small fin and short DT: https://youtu.be/PVkkVVL1Vgw (https://youtu.be/PVkkVVL1Vgw)

Dyl ok launch big fin: https://youtu.be/LZPOz_w9ifY (https://youtu.be/LZPOz_w9ifY)

Small fin short dt: https://youtu.be/qzTKJTd43oc (https://youtu.be/qzTKJTd43oc)

Dyl launch, small fin. lots of sink! : https://youtu.be/DhXMOfOszAg (https://youtu.be/DhXMOfOszAg)





Title: Re: Tern Free, composite TLG
Post by: OZPAF on May 07, 2015, 09:03:47 PM
I thought your DT stab was working well - however strong thermals will prove it. I thought the transitions with the small fin looked good and consistent and not overly sensitive to the climb angle.
good luck and thanks for the update.
John


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on May 08, 2015, 01:36:28 AM
updated plan

http://www.hippocketaeronautics.com/hpa_plans/details.php?image_id=7320 (http://www.hippocketaeronautics.com/hpa_plans/details.php?image_id=7320)


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on May 29, 2015, 08:33:46 AM
So Dylan and I went flying yesterday with the TernFree and had an absolutely ball. We caught numerous thermals and the pop stab DT worked well. I wouldnt say it was the fastest way to get out of lift but it was effective. It seems the launch and transition is awesome regardless of whether Dyl or I launch. We have very different launch styles. We now playing with trim to get the thermal flying optimised. Its pretty darn good but i think we can get it better. I cant express enough how good it feels to see this bird fly. RC has never made me feel this good about flight.
Big thanks to all for your input and opinions it has helped us achieve nirvana.

Regards
Blake


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on May 29, 2015, 08:37:27 AM
Dylan is quite calm when hunting thermals. Lol


Title: Re: Tern Free, composite TLG
Post by: OZPAF on May 29, 2015, 07:17:36 PM
Thanks for the update.
John


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on June 01, 2015, 07:19:34 AM
Im curious,  how tough are wooded tlg's? How do they hold up to lawn darts and cartwheels? I can vouch for the tern as its gone through tough times and is still intact and pretty damn  healthy considering. I wish i had all its bad moment on video to back me up but i only have these. What you think?

Blake


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on June 01, 2015, 07:24:08 AM
Tern free strength test: https://youtu.be/_4vHtC-pdpk (https://youtu.be/_4vHtC-pdpk)
Tern free strength test: https://youtu.be/_4vHtC-pdpk (https://youtu.be/_4vHtC-pdpk)


Title: Re: Tern Free, composite TLG
Post by: sweepettelee on June 01, 2015, 12:45:09 PM
You asked:  "how tough are wooded tlg's?"
Surprisingly tough, I would say.  Impacting an immovable structure is prone to damage most things, even dead tree wood flying objects.
Speaking for myself, my TLGs are several years old, tho I haven't had many recent chances to hurl them seriously.  I think it safe to say,
most current TLGs that follow the construction norm of balsa flying surfaces with bodies incorporating popup boom DT system are some
of the toughest, longest lasting FFs in most competitors fleets.

That said, I do find your parallel postings on the Composites Lounge Forum, of extreme interest...
The tough, but rubbery Leading Edge Molding Treatment you mentioned recently is a very important technique, which I wager will become
more widespread.

Thanks for posting your fine TLG efforts.
Lee R Hines


Title: Re: Tern Free, composite TLG
Post by: F3KBlake on June 05, 2015, 02:41:22 AM
Thanks Lee i appreciate your comments. I am always willing to share knowledge and admire people with the same philosophy.

Blake




Title: Re: Tern Free, composite TLG
Post by: Geneulm on June 05, 2015, 01:15:37 PM
Ok.  I've crawled out from under my rock to say: I WANT ONE!



Title: Re: Tern Free, composite TLG
Post by: F3KBlake on June 06, 2015, 05:33:11 AM
Dylan and I would really like to make them avalible to everyone. We discuss this subject at length. This is the reason why we are trying to get the community on board to make the wing of our dreams. Im sure Armsoar would be an easy way to distribute? ::)hmm

Blake


Title: Re: Tern Free, composite TLG
Post by: boca55 on June 06, 2015, 08:36:35 AM
Tern free strength test: https://youtu.be/_4vHtC-pdpk (https://youtu.be/_4vHtC-pdpk)
Tern free strength test: https://youtu.be/_4vHtC-pdpk (https://youtu.be/_4vHtC-pdpk)

Too big difference of angles


Title: Re: Tern Free, composite TLG
Post by: dylan1024 on August 31, 2015, 02:44:10 PM
Latest wing out of the molds. Just under 44grams


Title: Re: Tern Free, composite TLG
Post by: OZPAF on August 31, 2015, 09:03:48 PM
Nice work.

John


Title: Re: Tern Free, composite TLG
Post by: randoloid on December 02, 2015, 10:47:46 AM
That is absolutely beautiful!


Title: Re: Tern Free, composite TLG
Post by: Geneulm on December 02, 2015, 11:03:17 AM
Stunning.