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Dynam AT-6 Texan
#1

Manufacturer's web-site: http://www.dynam-rc.cn/Products_view_102.html

For once I decided to assemble a kit in the stock configuration - it took a lot to control my instinct to meddle with it, but the noise from RCGroups indicated that it was fine out of the box.

Assembly was not taxing, the only issues were ...
1. All the screws used to hold the wings on and the tailplane together were only 20mm long, this makes it simple for the manufacturing but I'll probably use some larger nylon bolts at a later stage.
2. The screws are sometimes placed in deep recesses and it's anyone's guess whether you're going to find the socket when you drop the screwdriver into the hole and start turning. It's also easy to try and overtighten the screws which will strip the plastic sockets very quickly.
3. It comes with those EZ style of connector for the horns on the control surfaces - I've never liked them that much - they're clunky, always seem to have too much slop, rely on a set-screw on which you can often burr the head, and you've really got to put loctite or CA on the retaining nut to be sure it's going to stay there. My collection of spare parts is a mess and I can't find things at the moment, otherwise I'd have replaced them with threaded clevis'.
4. I had to put some lead (dead weight) up behind the cowl to get the CoG correct.

The assembly manual said I cold expect a takeoff weight of 1250g and the static test showed 280 W so there weren't any reasons to upgrade the power train, but the 30A ESC doesn't have a huge amount of spare capacity.

It flew quite well and it wasn't difficult to make it look reasonably scale in the air. It would cruise about at about 65% throttle and the stock retracts performed perfectly even though I wasn't gentle with them. I perhaps had a little too much nose weight, so removed some of that for the second and third flights. It would loop from level flight at full power, but needed a bit of down-elevator to stop it sinking in a roll - not too bad and probably scale-like.

It's the first plane in which I've ever used expo - I thought it was about time to get acquainted with it. I think I might have started off with a little too much of it though because I was under-controlling the flair on landing. It's going to take a little time to get used to, and some of my landings were disappointing - not the plane's fault though, I got to get used to shoving the sticks around a bit more.

I plan on doing a kit-bash and converting it to a Wirraway, ready for Oz Day next year.


Steve Murray
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#2

Looks big on paper (web actually). Note: not "Gbanger big", just normal big. Does it have the same presence as the FMS T28s?
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#3

No mate - not that much presence. It's got a 1200mm wingspan, it's an FMS wannabe Wink

Steve Murray
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#4

It certainly looked the part in the air today !!

How much expo were you using ?

They say that you need about 20-25% on most models to make the controll response of the model liniar. So that should be a good starting point.

Expo isn't much good unless you put the rates up a bit as well. The idea is to keep the throws around the first half of the stick movement about the same as what your used to and then it gets progressivly more for the second half.

It would take a little to get used to if you accustome to most of the controll responce comming from movent around the center of the sticks travel.

“The knack of flying is learning how to throw your machine at the ground and miss.”

"When once you have tasted flight, you will forever walk the earth with your thoughts turned skyward, for there you have been, and there you will always long to return."  ~Leonardo Da Vinci
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#5

(02-09-2012, 10:00 PM)secant0give Wrote:  How much expo were you using ?
I started with 20% and when the deadband seemed too broad, I reduced it to 15% and was thinking as I left the field that I'd reduce it even further to 10% - but, reading your reply here Jason has made me realise that I was going at it back-to-front. I should perhaps leave it at 20% and increase the end-points instead!

(02-09-2012, 10:00 PM)secant0give Wrote:  They say that you need about 20-25% on most models to make the controll response of the model liniar. So that should be a good starting point.

Expo isn't much good unless you put the rates up a bit as well. The idea is to keep the throws around the first half of the stick movement about the same as what your used to and then it gets progressivly more for the second half.

It would take a little to get used to if you accustome to most of the controll responce comming from movent around the center of the sticks travel.

Yep - everything you've written here makes perfect sense, in the context of today's experience. I understand completely. Thanks for the input mate, much appreciated.
I also think I'll have to spend a bit of time on Phoenix getting used to it too - but I don't think it will take too long because I know what to expect and it will be easy to anticipate. Just need to re-calibrate my touch!

Steve Murray
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#6

Just a quick point for anyone not used to using EXPO or setting it up for the first time.
Make sure thet you dial in posative 20% and not negative 20% or you will be making the aircraft more sensative around centre stick rather than less. A nasty issue to have when you are trying to calm the aircraft down.
Gazz

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Hobbyking Voltigeur, Funfighter T28, Mirage 2000, Minimoa 2.4m Glider
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Don't ever let the fear of landing keep you from taking off!
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#7

Yes - thanks Gazz, positive expo on Spektrum equipment - but from what I've read it's the opposite on some of the other gear. It makes life interesting!

Steve Murray
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#8

It sure looked graceful on Sunday Steve.

Now to craft the worlds noisiest prop, to give that scale Wirraway sound. Smile

E-Flite Vapor
PZ Ultra Micro Mosquito
Durafly T-28 Trojan
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HK450 Heli
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#9

Cheers Angus - yep, there's a bit of work ahead of me with that one Smile

Steve Murray
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#10

Can Smuzz or any others advise just how much weight was added to the cowling to attain proper cg (70 to 75 mm behind the straight section of the wing leading edge) on the Dynam AT-6 Texan??
I am getting close to 3 oz. seems like a lot!! Using the Turnigy 2200 mah lipo battery, inserted right up to the stop in the cowling. tnx Dick
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#11

Sorry Dick - I can't give you a precise measurement at the moment. I broke my arm a while back and I can't get the prop-nut undone so that I can remove the prop and cowl to get at the lead and weigh it. It's going to be a few more weeks, unfortunately.
It's a while since I've flown mine (in fact a while since I've flown anything) but I remember thinking the perhaps Dynam's assessment of the CoG was a bit conservative and that it really should be further aft - but that was just a suspicion I had, which I've been unable to test.
Sorry mate, but it will be some weeks before I can help you at all.
Best wishes from Sydney, anyway Smile

Steve Murray
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#12

Smuzz sorry to hear about the broken arm. Are you in Sydney Austalia or Sydney, Nova Scotia?? I have weighed my weights and found I need just over 2 oz of lead at the nose cowl to balance at 7 cm. Thanks for your reply and heal up soon.... Dick
Smuzz, I see your club is in Australia G'day mate..
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#13

Dick - I'm not sure you're still interested, but I finally got airborne again today and the AT-6 was taken for some more test flights.

I've got a combined cowl and ballast weight of 81g which is more than the 2oz you were indicating. I've fitted lead flashing in the cowl as per photograph. I'm using the standard Turnigy 2200mAh 3S batteries which weigh about 195g too, so I'm not sure why we've got a variation.

Mine seems to be balanced well with this weight but I'm not pleased with the anaemic performance of the plane and I think I'll be making some power-train changes and going to 4S ... which means I'll have to fiddle with the weights all over again anyway.

... and yes, greetings from Oz, mate Smile

   

Steve Murray
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#14

I played golf again today (hey gotta get my fitness up for bushcare day) and missed out on seeing you in ther air again after a few months break (no pun intended).
No report on flying misfortune so I guess d'man is back. Great news Biggrin Thumbup
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#15

Smile Loved the pun, Wayne Thumbup thanks!

Steve Murray
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