Tweagle td. The best even better - RC Groups
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Nov 27, 2015, 05:52 AM
Alex Hoekstra's Avatar
New Product

Tweagle td. The best even better


Summary

The best DLG money can buy. If you are interested read on.

Tweagle td

So is this just another DLG?
Well yes but the goal was to make the best DLG on the market . The plane thats sets the bar.
The original Tweagle was already very good and was on par with f.e. the Snipe and could be flown slightly lighter in wind. The disadvantage was that the aileron connection was a bit hard to connect on the field. No problem for me and most guys that never take a plane apart but for those that do it was a real disadvantage. With the new Tweagle td those problems belong to the past. The aileron servo’s moved to the wing (td stands for top drive) and there is place to build inn a small connector or if you don’t take your plane apart just lead the servo cables in front to the receiver. The wing is connected with two screws and can be mounted in just a minute. To fit the aileron servo’s a new wing mold was necessary . The root of the wing was thickened slightly to make place for 8mm servo’s but the main difference is the fuse that went on a severe diet and lost almost one third of its total surface.

Wing

The wing sections stayed pretty much the same . The wing as it is has very low drag at launch and in glide and a very high CL max (lift) at higher cl’s giving the plane the ability to turn tighter and more economical then f.e. the same wing with zone sections. It also handles turbulence a lot better. The only change is the root were the first 5 cm are thickened by a couple of tenth of a mm to fit 8mm servo’s. Just 5 cm from the root transition starts over the next 2 cm towards the original wing sections. Hardly visible only when you blink the wing in the light you can see the differences.

Fuselage

After reading an artikel from Mark Drela about fuselage drag it was clear that it is the fuse were the most profit was to gain. Directly behind the thickest point of the fuse the airflow wil always be turbulent and can have up to 6 times the drag that laminair airflows have. Any decrease of surface there would decrease drag up to 6 times more as decreasing wing surface were the airflow is mostly laminair. So the fuse was redesigned completely. The wing pylon became even smaller and a carbon fibre 5mm round piece is fit in to make sure the wing sits sturdy on the fuse. Keeping the wing completely out of the turbulent airflow from the fuse decreases drag drastically. The stab pylon lost half of its length and half of its wide and became just big enough to receive the screws were the stab is mounted with. On the top a thin carbon plate to make the bed a bit wider to make sure the stab is mounted sturdy enough to handle power launches.

Stab.

With the original Tweagle i already started experimenting with smaller stabs. Since the Tweagle has a wing that can provide very high lift with very little flap the need for a big stab is really not there and test shows that a smaller stab has not only advantages in glide but also during launch especially at the push over. Bigger stabs have normally a larger CG range were the plane can be flown in but with bigger stabs i often noticed that the CG with maximum glide needs to be a bit forward of the CG range were the best climb is at the back end of the CG range. With the smaller stab the CG range becomes smaller but that proved to be a good thing since the best glide and best climb share the same CG and the plane pretty much always flies at its optimum once the CG is set. Just 0.5 gram in the nose seems to be enough at very turbulent days to make the plane fly like a dream.

Vertical

The vertical also went on a diet . Since the wings were already light. The fuse lost about 10 grams. The horizontal lost some weight and the vertical also Inertia became smaller and the need for a big vertical was not there any more. Surface went down to about 1.6dm2 which is small but proved to make some extremely good launches.

Best thing of al this dieting is not even the launch which improved by a good margin but the glide that got the best deal out of it.. With the new fuse and the small stab the CG went from 67/68 to 74 mm. With this CG and the low overall drag the glide is improved by not just a little but somewhere in the 25 to 30 % margin which is a guestimation but not an exaggeration. The Tweagle td is a lot faster the the original Tweagle with the same weight and can be flown 30 to 40 grams lighter . My 210 gram plane handles already some decent wind. At 230/240 its good in some stronger winds and i never needed to fly it more heavy then 270 gram over the hole season. Yes the Tweagle td is flying around since last June and already won the Dutch championships which is a series of 8 contests. Especially in the last contest were the circumstances in the afternoon became windy with weak thermals the td stood up and proved to make the difference.

The Tweagle td will come in 2 versions. 1)The light version 215 /225 grams
2) D box version 225 /240 grams.
Dealers,

To keep prices down i decided that all sales will go directly via me. I can accept pay pall if thats easier.
Last edited by Alex Hoekstra; Nov 27, 2015 at 06:04 AM.
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Nov 27, 2015, 09:45 AM
Have Fun and Just Fly!
l shems's Avatar
Alex,

this is really cool.

I was coming to the same point, you need a higher cl if you want to get good glide ratio's for speedy planes. But I am not convinced that lighter is better, because in the end range is more important than sink, at least in windy conditions.

For tasks where you have to rely on thermals (or rising air), since you simply cannot float long enough (every target more then say 3:00), weight is a funny thing.

Altitude gain from rising air will for a light or heavy plane be approximately the same, since we always assume that the plane rises "with the air".

But with a lighter plane, the effective glide angle on the upwind return is much steeper. So you need to rise higher, that is, you need faster rising air, to actually be able to return the distance you have lost in thermalling up.

Conslusion: lighter planes need stronger thermals in windy conditions.

What kind of ballasting system is in the tweagle TD??

Thanks for your reply.
Nov 27, 2015, 09:49 AM
Registered User
Maybe I missed it, but price?
Nov 27, 2015, 10:13 AM
Alex Hoekstra's Avatar
Quote:
Originally Posted by Viper39427
Maybe I missed it, but price?
http://europeantopplanes.nl/?page_id=48
For outside Europe its the prices without VAT.
Last edited by Alex Hoekstra; Nov 27, 2015 at 10:37 AM.
Nov 27, 2015, 10:35 AM
Alex Hoekstra's Avatar
Quote:
Originally Posted by l shems
Alex,

this is really cool.

I was coming to the same point, you need a higher cl if you want to get good glide ratio's for speedy planes. But I am not convinced that lighter is better, because in the end range is more important than sink, at least in windy conditions.

For tasks where you have to rely on thermals (or rising air), since you simply cannot float long enough (every target more then say 3:00), weight is a funny thing.

Altitude gain from rising air will for a light or heavy plane be approximately the same, since we always assume that the plane rises "with the air".

But with a lighter plane, the effective glide angle on the upwind return is much steeper. So you need to rise higher, that is, you need faster rising air, to actually be able to return the distance you have lost in thermalling up.

Conslusion: lighter planes need stronger thermals in windy conditions.

What kind of ballasting system is in the tweagle TD??

Thanks for your reply.
I partly agree with you but heavier planes don't climb as fast as light planes in thermals. The effective wing loading during banking goes up (with 45° bank angle the effective wing loading is about 1.4 times the normal wing load. So with Heavier planes the wing loading increases more then with light planes. Heavier planes also don't turn very tight and at low altitude this is a real disadvantage. Beside that lighter planes absorb turbulence a lot better with less height loss then heavier planes. Of course when thermals are booming sink is also present and you should't fly to light but its always nice to have the option when thermals are not that strong.

Ballast is a lollypop system with the lead simply hanging in the fuse on a steel rod which is stuck into the servo board.
Last edited by Alex Hoekstra; Nov 27, 2015 at 11:50 AM.
Nov 27, 2015, 11:19 AM
Have Fun and Just Fly!
l shems's Avatar
Quote:
Originally Posted by Alex Hoekstra
I partly agree with you but heavier planes don't climb as fast as light planes in thermals. The effective wing loading during banking goes up (with 45° bank angle the effective wing loading is about 1.4 times the normal wing load. So with Heavier planes the wing loading increases more then with light planes. Heavier planes also don't turn very tight and at low altitude this is a real disadvantage. Beside that lighter planes absorb turbulence a lot better with less height loss then heavier planes. Of course when thermals are booming sink is all present and you should't fly to light but its always nice to have the option when thermals are not that strong.

Ballast is a lollypop system with the lead simply hanging in the fuse on a steel rod which is stuck into the servo board.
Thanks for the reply. Gaining insights everywhere.

I'm really tempted to order one, but financials don't allow me right now. What is the delivery time once paid and ordered?

Need to prepare for the next season, and I might want a second plane next to my Snipe, for those lowlands conditions.
Nov 27, 2015, 11:56 AM
Alex Hoekstra's Avatar
Quote:
Originally Posted by l shems
Thanks for the reply. Gaining insights everywhere.

I'm really tempted to order one, but financials don't allow me right now. What is the delivery time once paid and ordered?

Need to prepare for the next season, and I might want a second plane next to my Snipe, for those lowlands conditions.
Guido,

At this moment just a couple of weeks but after a release like this its usual not long before the waiting time extends to a couple of months.
Nov 27, 2015, 01:33 PM
Retirement is good
Alex, excellent discussion on design theory and your execution. Many current DLGs still have clumsy wing/fuselage integration, subject to drag, though they are getting better. Your solution attempts to addresses that.

That said, sometimes going with “small” leads to unnecessary compromises in flight qualities and/or utility. In this case you promote smaller tail feathers. As an example, the drag increment for the horizontal stabilizer is actually very small, so have you sacrificed CG range, pitch damping and control authority unnecessarily except for the very highly skilled willing to deal with the higher pilot workload?

The reduction in fuselage size is another question in terms of utility. To answer that question could you provide information on the installed equipment you used, i.e., servos, Rx and battery. Also, being picky, pictures of the equipment as installed and the ballast would be of interest. While being really picky, a dimensioned 3-view including surface areas would also be of great interest.

Your comments on wing loading and the importance of climb rate are correct in my view.

Thanks and in all, nicely done!

Dick
Nov 27, 2015, 02:24 PM
Registered User
Destroy's Avatar
Wow, thinner and lighter definitely seems to be the trend.

In general, as models go in this direction, I do question the durability during the inevitable landing mishaps like 2 meter nose ins or sideways forces on rudder tips.

Awesome looking Tweagle td. though. Being a used Twister 2 owner, will give this model serious thought when I'm ready for a fresh model.
Nov 27, 2015, 03:30 PM
Alex Hoekstra's Avatar
Quote:
Originally Posted by rofly

That said, sometimes going with “small” leads to unnecessary compromises in flight qualities and/or utility. In this case you promote smaller tail feathers. As an example, the drag increment for the horizontal stabilizer is actually very small, so have you sacrificed CG range, pitch damping and control authority unnecessarily except for the very highly skilled willing to deal with the higher pilot workload?
I don't think i sacrificed anything on this plane. This plane flies smoother then anything i have flown before and it seems a lot easier to get some high performance all the time. Workload is actually pretty small compared to most planes. With the Twister3 i had a big stab and somehow i was always working to get the CG right. With low winds it needed to be far back but if a breeze past it ended with an of field landing because the plane didn't want to speed up. With theCG more forward this was not the problem but the plane didn't want to climb fast. With the smaller stab the CG of best glide and best climb come together and once set its good. Just with extreme winds and turbulence i will ad about 0.5 grams. Its different but not giving up anything.
Quote:
Originally Posted by rofly
The reduction in fuselage size is another question in terms of utility. To answer that question could you provide information on the installed equipment you used, i.e., servos, Rx and battery. Also, being picky, pictures of the equipment as installed and the ballast would be of interest. While being really picky, a dimensioned 3-view including surface areas would also be of great interest.

Your comments on wing loading and the importance of climb rate are correct in my view.

Thanks and in all, nicely done!

Dick
In the wing and fuse i use KST X08. Batterie 1200 round cell lipo(light planes 750) Receiver is 6 channel Frsky.
Wingsurface 19,8dm2
Horizontal 1.75dm2
Tomorrow i might post some pictures.
Nov 27, 2015, 05:13 PM
Aurora Builder
Seems like a really nice model Alex! I like the clean fuse/wing setup and the carbon pins for stiffness! And the price is very very good, with the euro down this is currently $608 USD outside the EU! Any idea what shipping stateside runs in terms of cost?

Edit: noticed shipping is listed as 60 euro outside the EC. Very good, less than $700 shipped right now.
Nov 27, 2015, 06:21 PM
Registered User
I've already bought my "last" DLG. Twice.

It may be time to buy another 'last" DLG...
Nov 27, 2015, 06:26 PM
Retirement is good
Quote:
Originally Posted by DrewV
I've already bought my "last" DLG. Twice.

It may be time to buy another 'last" DLG...
Drew, "may" is really weak... hurry and you will be just behind me in line. (LOL)
Nov 27, 2015, 09:41 PM
F3B and F3K
RetoF3X's Avatar
I am very fortunate that I have received a Tweagle TD for testing from Alex. I liked the characteristics of the old Tweagle, especially the aero of the wing seemed very well done (good penetration but also good performance at high cl and forgiving, i.e. wide envelope).

The fuselage and the wing and elevator pylon as well as the boom are very skinny. Surprisingly, the fuselage is very stiff in bending (and I do not say that lightly, as I am very particular about fuselage stiffness. It is en par with some special layup fuselages I had in the past).

Room for rc installation in the fuselage is fully adequate, see pictures. The "pod" gets sufficiently wide. Behind it, the fuselage gets skinny quickly, like on some of the newer full scale gliders. In the wing, MKS DS 65 barely clear the bottom surface. I made 4.8mm servo horns that almost fit under the cover. With thinner servos (KST 08) it should be not problem for the install. I made the wing horns to have 6mm height, so a mechanical advantage of 1:1.25
That way the linkages feel quite stiff, despite the rather small surface horns (I normally make the flap horns 8mm tall).

weigths:

Wing: 103gr
vertical: 5.1gr
horizontal: 4.9gr
complete airframe without rc gear: 150gr

I am looking forward to throwing and flying this plane.


Best regards,
Reto
Last edited by RetoF3X; Dec 01, 2015 at 09:38 AM.


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