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Old Jul 11, 2006, 11:37 PM
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flieslikeabeagle's Avatar
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Quote:
Originally Posted by Jeremy Z
It looks like you are happy with the end result of the long build. Congratulations!
Thank you! I am, indeed. The landing gear was the icing on the cake, I've always preferred ROG's rather than hand-launches.

At last Saturdays electric flight event there was a gusty breeze, and crosswind at that. The TSII got blown around a bit in the air, and it took a fair amount of side-slipping to get it to track down the runway centreline on the landing. Once I had it down on the ground, the wind kept trying to flip it over. But in the air, there was enough power to handle the wind quite easily. I made the little passengers in the TSII's cabin pretty airsick, I think, after the first few loops, rolls, stall turns, and spins.

Quote:
Originally Posted by Jeremy Z
I would be curious to see it fly next to mine.
That is something I would like to see also. A classic case of there being more than one way to skin a ca...oops, I don't want to offend the pet police or our two cats for that matter, lessee, more than one way to build a Twinstar.
Quote:
Originally Posted by Jeremy Z
Of course, yours will be easier to land without needing a lot of runway. (even with my fancy flaperons)
Y'know, I was thinking about wheel brakes the other day - at 33 oz without landing gear (perhaps 36 oz with them), my TSII glides in very slowly for landings, and on grass it does not roll very far before friction halts it. But on asphalt, it rolls a fair distance. Some way to brake it would be nice!

Have you heard about the E-moli cells? Milwaukee has released a line of cordless electric tools called the "V28" line, which use a 7S, 3000 mAh lithium-ion pack. Replacement battery packs can be found on the internet for aproximately $105 (USD) delivered to your door. The pack is housed in a plastic casing and contains built in balancing and charge/discharge protection circuitry, which unfortunately is no use for RC applications, and needs to be discarded. Even so, the cost is only $15 per cell - somewhere between half and one-third the cost of an equivalent lithium cell bought from an RC manufacturer. One V28 pack will give you two 3S packs and a single cell left over, or a 3S and two 2S packs, or - well, you get the idea.

By the way - what we call lithium polymer or lipo cells are really lithium ion cells, according to a guy who knows a lot more about battery chemistry than I do. So don't be concerned about the E-moli's being called lithium ion cells - your expensive ThunderPower or Kokam "lipos" are also in fact "li-ions".

These E-moli cells are housed in a hard metal case, like the older NiMH and NiCd cells, and so are much more robust than the lipo packs we use for RC with their fragile plastic envelope. Each 3000 mAh cell weighs 100 grams. However a pack of the E-moli cells only weighs about half as much as a NiMH or NiCd pack of equivalent capacity and voltage, though they are heavier than an equivalent (pouch type) lipo pack.

Many folks on the electric helicopter forum are using these packs to power their large electric 3D helicopters, so you know they are more than up to the job of flying a Twinstar II (which is fundamentally a large foam trainer, and far less demanding of the batteries than a 3D electric helicopter). Steve Neu (of Neumotors fame) tested these cells, and found them good for sustained discharge rates of 10C to 12C. These are 3000 mAh cells, so that equates to sustained currents of 30 to 36 amps.

Imagine this: you and a buddy buy one of these V28 replacement batteries, and divvy up the cells. Solder three of them in series and you have a $45, 10C, 3000 mAh lithium pack, which will fly a brushless Twinstar very well and for a long time on a charge, while weighing half of an equivalent NiMH pack, and costing less, too.

By the way, one of the Apex 15C, 3S, 2100 mAh lipo packs I'm using in my TSII can be had for another eleven bucks over the cost of the 3S 3000mAh 10C E-moli pack, i.e. $56. It weighs 160 gm instead of 300 for the E-moli pack, but only has has 70% of the capacity (mAh): http://www.epyaya.com/product_info.p...oducts_id=1428

-Flieslikeabeagle
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Old Jul 12, 2006, 12:12 AM
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53859 Niederkassel, Germany
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Quote:
Originally Posted by flieslikeabeagl
...
Y'know, I was thinking about wheel brakes the other day - at 33 oz without landing gear (perhaps 36 oz with them), my TSII glides in very slowly for landings, and on grass it does not roll very far before friction halts it. But on asphalt, it rolls a fair distance. Some way to brake it would be nice!
...
-Flieslikeabeagle
I use a Schulze Car-ESC on my old Twin-Star with reverse, for steep approaches and to stop it when flying on snow/ice.

More extreme - VPP:

http://www.rcgroups.com/forums/showp...postcount=2223

Jürgen
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Old Jul 12, 2006, 01:35 AM
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wow.... and here i am just barely getting comfortable flying my twinstar.... awesome vid!
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Old Jul 12, 2006, 06:02 AM
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Well great job from the cameraman for following the plane that good. Good pictures.
Excellent skills of the pilot too.

Still i do not see the point of tuning a TS2 into an acrobatic plane... the guy should buy an Acromaster instead!
The TS2 is such a nice plane because it flies so real for me (with stock motors)... what a pity to turn it into such an acro monster!
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Old Jul 12, 2006, 06:29 AM
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Quote:
Originally Posted by LaMuse
Well great job from the cameraman for following the plane that good. Good pictures.
Excellent skills of the pilot too.

Still i do not see the point of tuning a TS2 into an acrobatic plane... the guy should buy an Acromaster instead!
The TS2 is such a nice plane because it flies so real for me (with stock motors)... what a pity to turn it into such an acro monster!
Fortunately because there is no rule rule that says the aircraft must remain standard and you can't have fun.

Tony
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Old Jul 12, 2006, 09:03 AM
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Jeremy Z's Avatar
Northern IL
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Quote:
Originally Posted by flieslikeabeagl
By the way - what we call lithium polymer or lipo cells are really lithium ion cells, according to a guy who knows a lot more about battery chemistry than I do. So don't be concerned about the E-moli's being called lithium ion cells - your expensive ThunderPower or Kokam "lipos" are also in fact "li-ions".
beagle, I don't think this is right. Otherwise, my Multiplex LN-5014 wouldn't have different charging parameters for LiIo and LiPo. I'm sure they would have rather had one set of charging parameters. It is an interesting idea, but maybe not worth the trouble. (8-10 C LiPos are probably lighter and around the same price. Maybe less.)
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Old Jul 12, 2006, 09:20 AM
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Quote:
Originally Posted by Jeremy Z
beagle, I don't think this is right. Otherwise, my Multiplex LN-5014 wouldn't have different charging parameters for LiIo and LiPo. I'm sure they would have rather had one set of charging parameters. It is an interesting idea, but maybe not worth the trouble. (8-10 C LiPos are probably lighter and around the same price. Maybe less.)

Jeremy,

Of coure it is not right. The polymer in Lipo cells acts like an ion, but it is NOT a metallic ion like those present in Li-Ion cells.
Anyone saying the opposite is clueless in chemistry, and I do happen to be a chemical engineer...
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Old Jul 12, 2006, 09:48 AM
MKH
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Ohio
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Almost everyone that sold lipos initially called them lithium ion polymers. They further explained the cells were lithium ions in a soft case. Lots of folks had that in their heads, even if its not accurate.

Beagle, I enjoyed your TS2 contributions and appreciate your input. I know of several folks building and/or flying your setup, they just won't post here for some reason. Jurgen's videos have been a great help too.

MKH
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Old Jul 12, 2006, 12:48 PM
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Oakdale, MN, USA
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re: Beagle's setup

MHK, Beagle, and all:

Been away from the Zone for a while flying new planes. My twinstar II has a very similar setup to FB's, namely the twin Esskay 400 XT motors and T-Bird 18 ESC's. I have been flying it with a PQ 2100 3S1P pack at about 40 ounces. Not sure really why mine is so heavy compared to the Beagle's, but with 8X6E APC props (which are kinda heavy) it still flies quite nicely. I even caught a bit of a thermal last Sunday and shut the motors down for a bit. The club guys like the way it flies, even though it may not be as fast as some. It has already flown with heavier packs than the one I settled on and has plenty of power to haul more weight. The climb is outstanding, no matter which way the wind is blowing.

I saw an example of Bill Glover's landing gear on a TS-I recently at a fly-in and I expect I will get around to that mod, too. One of the attached photos is on the C/G machine, balanced on the factory spec. Mine flies fine there. Photo quality is not good. They were taken with my Treo.

Regards,

Dale Case
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Old Jul 12, 2006, 01:00 PM
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Quote:
Originally Posted by LaMuse
The TS2 is such a nice plane because it flies so real for me (with stock motors)... what a pity to turn it into such an acro monster!
Then by all means build it and fly it the way you like it!

The TSII is basically a very expensive foam trainer. For some who are still learning to fly, the expense is worth it for the extreme durability of the Elapor, or because semi-scale foam twins are still a bit of a novelty in the RC flying world. But others here learned to fly long ago, and an expensive, underpowered trainer is not particularly appealing. Adding extra power and aerobatic ability to the TSII adds interest to it, especially since Multiplex engineered a nice airframe here, capable of much more than just puttering in lazy circles.

Once you have an improved power system, you have more choices, more flexibility. Want to fly "scale"? Pull back the throttle. Want to make full use of all four channels with some enjoyable aerobatics? The capability is there. Need to battle some gusty wind? You have the power needed to do it.

-Flieslikeabeagle
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Old Jul 12, 2006, 01:05 PM
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Quote:
Originally Posted by Jeremy Z
beagle, I don't think this is right. Otherwise, my Multiplex LN-5014 wouldn't have different charging parameters for LiIo and LiPo.
Jeremy, as I said, I'm not an expert on battery chemistry, but the guy I heard that from is. He's a research boffin whose work involves lithium batteries - he's well qualified to make an authoritative statement on the subject, and I believe him.

Apparently there were some early generation lithium-ion cells that required a lower voltage charge cutoff, but it has been many years since those were made.
Quote:
Originally Posted by Jeremy Z
It is an interesting idea, but maybe not worth the trouble. (8-10 C LiPos are probably lighter and around the same price. Maybe less.)
You're talking about the E-moli cells? Yes, regular lithium batteries of equivalent capacity and voltage are somewhat lighter. However, the E-moli cells are about half the weight of an equivalent NiMH or NiCd pack.

10C lipos for less? If you find a 3S, 3000 mAh, 10C lipo pack for $45, please let me know where. I'd love to buy one.

-Flieslikeabeagle
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Old Jul 12, 2006, 01:26 PM
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Quote:
Originally Posted by MKH
Beagle, I enjoyed your TS2 contributions and appreciate your input. I know of several folks building and/or flying your setup, they just won't post here for some reason.
MKH
Thanks! I know of several also, as I received quite a few PM's over the months asking for information on my setup.

While numerous venomous attacks on my posts by an emotionally troubled individual have kept others from posting, it is nice to know that the verbal flack hasn't kept several other RC pilots from weighing the evidence, and enjoying this very nice and relatively inexpensive brushless upgrade to the TSII.

Many months ago I met a local RC pilot at Robins Hobby, an RC hobby shop in Burbank, CA. He asked me about some of the items I was purchasing, and I told him they were for my Twinstar II build. He asked for details, and when I told him I intended to use the $20 Esskay 400XT motors, he was very interested and told me he would very much like to see the outcome. I haven't seen him since.

This last Saturday I flew my TSII at the Black Sheep Squadron Summerfest 2006, an all-electric meet in Van Nuys, CA. ( http://www.modelaircraft.org/comp/Co...wc07082006.htm ). Immediately after my first flight of the day, as I was walking back to the pits, a man came up to me to ask about my TSII. He was surprised to recognize me as the same person he'd talked to in Robins Hobby months ago, and completely shocked to find out that the flight he'd just seen (which included a very short takeoff roll into a vertical climbout) was flown with the twin Esskay 400XT motors. He told me he'd expected those two tiny cheap motors to be marginal at best on the TSII. Boy, was he wrong!

I would really like to get some video clips of my TSII in flight. I don't have the video equipment, nor any video editing skills, but perhaps I can talk someone at my field into doing it for me.

-Flieslikeabeagle
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Old Jul 12, 2006, 01:56 PM
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Quote:
Originally Posted by Dale Case
My twinstar II has a very similar setup to FB's, namely the twin Esskay 400 XT motors and T-Bird 18 ESC's. I have been flying it with a PQ 2100 3S1P pack at about 40 ounces. Not sure really why mine is so heavy compared to the Beagle's, but with 8X6E APC props (which are kinda heavy) it still flies quite nicely.
Nice TSII, Dale! I like your color scheme. The thin black stripes accent those red areas so well. I should really get some tape pinstripe and do that with my TSII!

I just re-weighed my TSII, and with the new bigger 2100 mAh, 15C, 3S lipo pack, the new landing gear, and the heavy Graupner 8x6 counter-rotating props, it weighs 39 oz (1.1 kg). So now the weight mystery is solved, your TSII and mine are within an ounce of each other (though the weight of the landing gear is included in mine).

My TSII used to weigh 33 oz when I first flew it months ago with the smaller and lighter 2000 mAh, 10C, 3S lipo pack, the lighter GWS 8x6 HD props, and no landing gear. I had not realized the changed equipment had been responsible for this much weight gain. Fortunately, the improved performance of the 2100 pack has more than compensated for the weight gain, as my TSII now has vertical on a freshly charged battery.

Speaking of landing gear, my removable main wheels are entirely based on Bill Glovers approach - nested square brass tubing, soldered music wire, and all. The nose wheel is a different setup - I built a steerable nosewheel assembly and managed to hook it up to the existing rudder servo. The servo operates an aluminum tube with a wheel-collar on it, while the actual nose wheel is carried by a piece of bent music wire that slips into the aluminum tube and is retained by tightening the wheel-collar, slightly crimping the aluminum tube down onto the wire. The nose wheel can be easily removed by loosening the wheel-collar setscrew, and this attachment method keeps any severe shock torques from being transmitted to the servo via the nosewheel.

Quote:
Originally Posted by Dale Case
I even caught a bit of a thermal last Sunday and shut the motors down for a bit. The club guys like the way it flies, even though it may not be as fast as some.
I never managed to thermal mine, but its a floater with the power off, all right. When I lost a prop mid-flight the other day, the plane was ony a little above treetop height, but I still had to do a deadstick circuit of the rather large park before the TSII lost enough altitude to land it.

At least three of the regular RC pilots I meet at the park have told me they were considering getting a TSII after seeing mine fly, though I think the high purchase cost of Multiplex products in the US is putting them off. A hundred bucks is a hefty price to pay for a few large chunks of packing foam and a couple of fifty-cent ferrite can motors!
Quote:
Originally Posted by Dale Case
It has already flown with heavier packs than the one I settled on and has plenty of power to haul more weight. The climb is outstanding, no matter which way the wind is blowing.
Yes indeedy! Other TSII's are flying at well over 50 oz, so it is immediately obvious there is capability to carry at least 10 oz of payload in these lighter TSII's. With the very strong performance from the 400XT motors, I have no doubt the actual payload capability is considerably more than that.
Quote:
Originally Posted by Dale Case
One of the attached photos is on the C/G machine, balanced on the factory spec. Mine flies fine there.
Curious! Mine flew like a 3D plane at that CG, it wanted to hover and would not "point" at all, instead being nervous and twitchy. It now flies much better, but still does not track very well and I think the CG needs to be a bit further forward.

I like the CG quite far back on more aerobatic planes that spend a lot of time inverted, with the TSII I don't want to loose good tracking and pointing to enhance inverted flight which is done rarely.

-Flieslikeabeagle
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Old Jul 12, 2006, 04:07 PM
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Joined Jun 2002
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Quote:
Originally Posted by flieslikeabeagl
Its been a long time since I posted to this thread, but I have received a number of PM's recently asking questions about the powertrain and wiring I used in my TSII (two Esskay 400XT motors, $20 each at the time, since then down to $17 each on sale). It seems an update is overdue.
-Flieslikeabeagle
Flies Like A Beagle, do you have a link to these motors at this price?
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Old Jul 12, 2006, 04:21 PM
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Oakdale, MN, USA
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Flieslikeabeagle:

How would you feel about sending me a PM with a photo of your nosegear?
I have a feeling that I would really enjoy landing gear with this plane, although to be honest, I still have a little trouble setting it down where I want, even with the spoilerons.

Monday night at the club fly-in meeting at Tri Valley RC Club, south of MPLS-St. Paul, there was a beautiful paved east-west runway with beautiful approaches. The only plane with landing gear I had with me was a Tiny-X! And it doesn't need much runway because it uses the same motor/prop combo that use on the Twinstar II, the 400XT with 8X6E APC prop. Wth a total weight of 7.5 ounces and 17 ounces of thrust (static, my measurement) on hand, it has a take-off run of maybe 2 feet!

I flew the Twinstar II, the Tiny-X, my Kyosho T-33, and my Superfly. I also had a fellow club member with more experience fly and set up my new LiftOff XS. When I charged those two 2100 packs from the Twinstar that night neither one needed much more than 1000 mAh to full. I am very pleased with the motors. You may have noticed I mounted mine in FRONT of the firewall and they stick out like little Allison gas turbines. I might still fiddle with the props some, but I am pretty pleased with the overall handling.

The one bad thing I have found about using these motors is the variablity that exists in build quality. I needed to swap one motor out because it consistently developed less power than the other, more than 200 RPM at full throttle. The replacement I had on hand is a very close match, but someone without a tach or some experience could get into trouble with these motors.

One guy at the field, old hand at RC but new to electrics, asked about the Twinstar II's low speed handling. There were quite a few planes in the circuit at the time so I took it up high and shut down the motors and held the elevator up just a bit, walking it into a stall. It just mushed along at a very slow speed, still decending slowly and fully controllable with the rudder. That is one thing I really like over the Easystar. Power off, the Twinstar II rudder is still effective.

My color scheme is OK, but I need some underwing contrast. And new glasses, too!

Regards,

Dale Case
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