|Nov 06, 2013, 08:36 AM|
Gartt GT500 TT DFC
Taking a chance on smaller, newer to market Chinese companies is always a gamble. Having to play the odds about quality, parts availability just as much as price. I decided for my first 500 class helicopter to try and use ShenZhen GARTT Model Co., LTD. They are the manufacturer of the current HobbyKing GT500TT FBL kit. I know there are many that have bought the current HobbyKing kit and it is all over the board with respect to quality assurance, but in my past experience with Chinese manufacture, I have noticed that same branded parts can be of better quality than contracted manufacture. With this history I decided on the Gartt GT500TT DFC.
I purchased my Gartt kit from their eBay listing. They have an eBay store located here: gartt-rc. Their company website is Gartt Model Company. The kit was purchased on October 17, 2013 and arrived, after a short delay in US Customs on November 5, 2013.
The kit was shipped in a plain brown box. It was not double boxed so if you decide to order one for yourself please note that it is not the strongest box in the world and might result in damage while in transit. Mine did not arrive with any damage to the carton it came in.
Upon opening the box you can see that the packaging is separated into three compartments. The largest compartment holds the partially assembled frame as well as the fiberglass canopy. The smallest section has bagged sub-assemblies including the tail and stabilizer fins, the DFC head and swashplate unit, the tail assembly and tail blades, a package of bolts, rotor foam brace. The last bag contained the skids and skid struts. The final compartment contains the main rotor blades as well as the tail boom, torque tube, rear servo push rod and guides, torque tube bearing pre-installed into the tail boom.
The canopy and frame are all wrapped in foam and there was no damage to any of the included parts.
_IGP5645.jpg on Flickr
_IGP5646.jpg on Flickr
_IGP5647.jpg on Flickr
In the following posts I will try to examine each of the supplied parts and give a brief appraisal of the quality, finish and fit.
|Nov 06, 2013, 08:37 AM|
Here is a nearly complete list of everything included in the kit starting with:
You will note that there are no instructions that come with this model. Not even a sheet with a list of all the parts. I would strongly suggest to Gartt to include at the very least a parts list and an exploded view. Since the box is plain brown corrugated cardboard there is no picture to go by. There are also too few images on the Gartt website to fully assemble the kit. This would make it a bit more of a challenge for those that have never put a model kit together.
You will notice that there are a lot of parts already put together into assemblies. This certainly has the potential to speed up the build process but in most cases it will actually slow it down as everything will likely need to be disassembled and checked for things like greased bearings and thread-locked bolts.
Over the next week or so as the rest of the build parts arrive I will take apart all these assemblies to verify they are reassembled with standard build practices. I can say that the frame, which I have already disassembled did not have any thread-lock on any of the bolts going into the aluminum parts. More on this as well as pictures as the build progresses.
|Nov 06, 2013, 08:37 AM|
A look at a few parts
Finally had a chance to do some assembly on the Gartt kit. First I had to take apart the sub-assemblies to make sure they were put together with accepted practices. So here are a few pictures of the parts and my thoughts on them. First up the blades:
The finish on these is not too bad with just a hint of orange peal in the clear coat. The were fairly well balanced using a static balance test as well as equal in weight. I am sure they will not perform as well as a set of carbon blades but will do for my first 500 class heli.
Next up the canopy:
The paint as far as graphics goes seems to be fairly crisp, there are quite a few flaws in the clear coat. One can be seen in the lower middle, there is a big run in the clear in that area. Another issue is around the sharp bend where the windshield would start show signs of cracking in the clear coat. The fiberglass appears to be intact but the stress of installing and removing the canopy will undoubtedly lead to paint failure.
The airframe actually look very well made as it is a die cut sheet of carbon fiber board it is hard to mess it up. The edges are a bit sharp but a small anount of time with some 320 grit sandpaper will take down those edges in a hurry. I will have to dismantle this to make sure everything that is metal to metal has thread locker on it. One thing that is noticeable, the battery shelp has a very pronounced warp in its length, it curls up on both ends and will require some attention. The plastic pieces all have mold flash on the edges so they do not sit completely flat, again necessitating a touch of sanding to smooth out.
The rotor head and swash plate are preassembled but will be taken apart and checked for proper lubrication and thread locker. There does not seem to be any slop in the unit itself, but time will tell just how well its manufactured. The shaft measured the correct diameter and slid through all bearing with a good interference fit.
The main gear is also preassembled and other than a dry bearing looks to be quite serviceable. It does not rok at all when the main shaft in inserted.
The tail fin and stabilizer appear to be as well made as the frame sides and just a bit of sanding is needed to knock down the sharp edges. The tail unit comes assembled and everything is snug, with the exception of the washout bushing. The bushing seems to hang up just a bit as if it is binding near the end of it's throw. I will investigate this and report on it when I disassemble it before final build.
Tail blades and anti-rotation bracket are plastic and not much else can be said about them. The support struts are carbon rods with aluminum ends glued on. The glue is not holding so will need to be redone. The ends are snug so so golf shaft epoxy should provide a more than adequate bond. The torque tube is of typical construction and the splined ends fit into the tail box and tail assembly with no play. The boom already has the bearing located about a thrid of the way from the front end abd the torque tube slides past it nicely with no binding. The boom is aluminum, would rather have seen this be a carbon part. GT500-FBL TT is printed on both side of the tail boom.
The landing struts are a firm plastic, very stiff but not brittle and the skids are an aluminum tube with a nice even radiused bend on one end and black end caps.
Overall the quality of the parts seem to be pretty good, no loose parts. The finish of the aluminum parts could be better,nearly all the machining marks are visible, but this I am sure is a cost saving measure to keep the kit reasonable in price. Asid from the issues with the mold marks on the plastic parts and the warped battery tray they are otherwise clean and fit reasonably well. The tailbox mounts precisely located by four screws and a key on each side. One thing that is missing is the key for the main shaft bearing blocks, the keyhole is in the frame but the blocks are smooth on the mating surface, again I think to make macining easier and cut costs. So far it doesn't look as bad as some say the new HobbyKing 500TT kit is, when I start dismantling and reassembling we will know more.
|Nov 06, 2013, 08:38 AM|
Things aren't always as they seem.
Okay, had just a bit of time over the Thanksgiving holiday to finish up the build, got everything put together and had it on the table for bench testing w/o blades. Got all servos adjusted and then set up the GV8000 (vBar mini clone). While I was checking throttle response the tailbox blew up and scattered little pieces all over the room. I do not have any images but will post some later.
Specifically what broke was one of the short arms in the tail rotor control set, once that went the the ball link snapped and one of the heads sheared off the tail holder bolt (the one going into the rotor feathering shaft) sending that holder clear across the room. More stuff started to bend before I could get to the throttle hold button. It also bent the servo control link, but did no other damage to the model. It is a good thing I wasn't in the air and there were no blades on. This all happened in a matter of seconds after spin up to check throttle endpoints.
This will just add more fuel to AtomicSkull's premise that you should never go cheap.
I am going to replace it with an Align tailbox. So far the rest of the kit still looks good and there are no apparent wobbles or loose parts, anyone can end up with a defective part every now and then. I am still not going to write off the entire model just because a single part failed. Parts fail on other models too. Just trying to keep some perspective here. The good part is that the part failed immediately instead of after 10 flights.
|Nov 06, 2013, 08:38 AM|
Here is a brief update, time has not allowed me to finish up and maiden this helicopter but I did get everything assembled. Below is a parts list for power system and electronics:
Turnigy HeliDrive SK3 Competition Series - 4249-1600kvControl
Mi Digital High Torque MG Servo 6.0kg / 0.11sec (x3 Cyclic Servos)Other Parts and Upgrades
Complete Align 500 Tail Rotor Assembly W/ 70mm CF BladesThe metal upgrade parts were used to stiffen up the frame but mostly unnecessary, the only actual item needing to be replaced was the battery tray which arrived warped. The Spartan Blue-Link is used to get live readings from the GV8000 with my Android phone. The GV8000 works with the Mikado vBar Android Software (https://play.google.com/store/apps/d...bi.vbarandroid). I went with the OrangeRX after seeing a lot of good reviews and I simply don't fly at the limits of my sight.
The Align Tail Rotor assembly was used to replace the Gartt because with the 14T pinion I think I was running too hot (headspeed wise) and one of the bolts failed which caused the Tail Assembly to explode in a bunch of pieces at WOT while bench testing. If I replace worn, crashed or broken parts they might as well be upgrades.
|Nov 06, 2013, 06:59 PM|
Thanks, don't have all the parts yet but should have everything I wanted to put in this helicopter by the end of the month.
|Nov 21, 2013, 08:22 PM|
Gartt makes the HK Assault 700 and HK550 as well as some of the 500 and 450 Hobbyking kits (but not all of them, some are Skya kits). If you compare the HK kits to the Gartt kits you can easily tell which 500 and 450 kits are Gartt and which are Skya, the Gartt kits have black anodized parts (and are identical to Gartt parts in appearance) The Skya kits have titanium grey parts.
Notice the differences between these two kits and how one of them has the exact same frame cutouts as the Gartt kit as well as the same angled pitch control arms on the grips (Align grips don't look like this)
The first one is made by Gartt, the second is made by Skya.
Also, this TT kit is also a Skya kit (note the grey parts)
|Nov 22, 2013, 12:08 AM|
Yeah, been working 6 days a week and in my little spare time been working on collecting screenshots for the new version of deviation for the devo transmitters. I still don't have everything I need to build it up. Will probably get back to it sometime next week.
So far there are a few items I have replaced, the plastic battery tray was warped and since I was replacing it I switched it to aluminum. I also got a lexan receiver shelf to replace the very flimsy plastic one. I need to shorten some of the servo cables.
Its just a few little things that need attention.
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