DT600 Review

Review written by Bobby Barr

DT600.jpg
  • Rotor Diameter 1346 mm (53″) w/ 600 mm blades
  • Length 1158 mm (45.6″)
  • Height 317 mm (12.5″)
  • Width 160 mm (6.3″)
  • Blade length 600 mm (23.6″)
  • Main shaft 10 mm
  • 11 Tooth Pinion Gear
  • 104 Tooth Main Gear
  • Gear Ratio 9.45 : 1
  • Tail Drive Ratio 1 : 4.0
  • Weight with electronics (no battery) 2300 grams (5.07 lbs)
  • 3720 grams (8lbs 3oz) with Pulse 6s 3300mah

Links-

Equipment used-

DT600_front.jpg

Supplies needed-

  • Threadlocker (Red & Green paste used)
  • Grease
  • Oil
  • CA

First Impressions-

This year at IRCHA brought several surprises. The day we arrived I met up with Henry Caldwell. Henry has been involved in the helicopter industry for years. While catching up with Henry I discovered he is now working for DT Helis, a company that I admittedly had limited knowledge of. The foundation for his excitement quickly became apparent as he began showing off the new version 2 Dart Tin helicopters that he had just recently acquired. My friends and I studied the three helicopters for quite some time. The DT520, DT600 and DT700 all had features that led me to believe that DT was not only committed to a great value, but also committed to innovation in their products. That encounter left me with a desire to get Henry on the RC Today Show for an interview, as well as Shannon Turner, the US distributor of DT helicopters.

DT700.jpg

 DT520.jpg

After the interview I knew it was only a matter of time before I owned one of these helis. Eventually I decided on the 600 because I could only afford to purchase one of the three. Why not choose the size in the middle? It just so happened that my current 600 was several years old and I just felt it was time for a new heli in that size.

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Package-

It was a bit of a disappointment when the package arrived and I saw that the box was for a version 1. At first I believed that a mistake had been made, but closer inspection of the box revealed that the sticker had a V2 on it. The hard fact is I didn’t like it, yet once I began pulling the parts out of the box I quickly realized that it is the helicopter that concerns me, not the box.

All of the parts were packaged very well. I could not find any scratches, cracks or dings in any of the parts including the canopy. The majority of the helicopter was already assembled with thread locker and grease already applied where needed. There were only a few bags that had minimal loose parts inside. There was also a spare tail boom included in the kit.

I did notice that the ball links were already assembled and installed on the head. This is a nice touch, but all of the links felt very tight on the ball. They were also different lengths. For example the 2 links between the swash and blade grips differed by 3 mm.

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Manual-

DT is at a major disadvantage in the manual department in my case. I have assembled kits from manufacturers such as Next D and SAB that flat out have amazing manuals. Luckily the DT manual isn’t bad. It is not printed in color, but is a total of 26 pages that has fairly clear drawings in black and white. Although the helicopter comes mostly assembled, the manual goes into detail on each step as if it wasn’t. It also includes the specifications on the back cover. A nice touch is that it lists the number of teeth on the pinion, as well as the drive ratio.

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Build Preparations-

Typically prior to building a heli I spend a couple of hours cleaning all hardware with rubbing alcohol and deburring the sharp edges of all carbon fiber. In this case there wasn’t really any loose hardware to speak of, and all of the carbon fiber was assembled. Here I had a major decision, either disassemble the entire helicopter to insure proper grease and thread locker, or complete the final assembly. In the end I decided to take the middle road. I tested numerous screws and found that DT used thread locker on all of them. Truthfully the product they used may even be too much. I tried to loosen the bolts that hold on the main blade grips and thought I was going to strip my tools. I will go back soon and heat up the head of the screws as stated to do in the manual. Hopefully that will work so that I can check proper assembly of the head components and grease.

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Build- Let the fun begin…

As previously stated, the helicopter is mostly assembled. For this reason I used the manual as a point of reference rather than a step by step guide.

The first thing I did was to install the canopy mounts onto the frame. The front/lower mounts are plastic, while the rear/upper mounts are aluminum. Nice touch, but I prefer that DT put small flats on the aluminum mounts to allow you to tighten them without scarring them with pliers.

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I installed the skids in minutes. Simple, yet effective design. Would be nice if the struts would be black or a whiter white. The firmness of the struts feels perfect. Time will tell.

I noticed that there was not a flat ground on the main shaft for the locking collar. So I took the time to grind one using my rotary tool. With that done I installed the main gear and main shaft which already had the head, swash and blade grips complete and ready to go.

DT600_tail.jpg

I disassembled one side of the tail case so that I could install the belt over the tail pulley. The belt was already installed in the frame, and bundled ready for the tail boom. I used a long rod to pull the belt through the tail boom and around the pulley. I slid the tail boom into the frame and reassembled the side plate onto the tail assembly. Once that was done I pulled the tail boom until the belt was tight, and I secured the tail boom in place. The horizontal tail fin and boom supports were already attached to the tail boom. All that was needed was to loosen the horizontal fin clamp and attach the long end of the tail boom supports to the frame. The hardware was already in the frame ready to go. No need to dig in parts bags trying to figure out what you need.

The canopy comes already painted with grommets installed. How nice is that?

At this point the kit was built, time for electronics installation.

DT600_frame1.jpg

Electronic placement & wiring-

The first thing I installed was the motor. Everything needed was in there including the motor screws. Unfortunately they were too long and I found that if inserted all the way the end would contact the windings. I ground the screws shorter by about 1/16″. Next I mounted the tail servo. Be aware that since the servo mounts in the frame, your tail endpoints will need to be adjusted almost every time you adjust the belt tension. There is a hole in one of the side frames that allows the tail servo horn to be accessed without a problem. The cyclic servos have a nice mounting system that allows the front two servos to mount vertically, and the elevator servo mounts horizontally in the rear.

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I could not find a great place to mount the flybarless controller. There is a flat spot on the top/rear of the frame that should be a perfect place. The only downside to that location is there is a screw that the flybarless unit would be covering up. That screw protrudes from the top of the plate almost 1 mm. In order to mount it on that plate I would have needed to countersink the hole much more so that the head of the screw would be lower than the plate. I ended up mounting the Brain on the side of the frame, and mounted the TM1000 telemetry unit to the other side frame. Stuck the HobbyWing ESC to the front tray, which then gave me the issue of where to mount the receiver battery. For now I strapped it under the frame between the landing skids. That may change if I decide to switch to a BEC later on.

The frames are very close together. This gives great rigidity, but doesn’t allow any place for electronics to mount or wires to run. Normally this wouldn’t be that big of a deal. However I am also using telemetry with a temperature wire, RPM wire and battery wire. This adds complexity and even more wires to tidy up. Since there isn’t any place to hide the wires, I chose to use a wire mesh wrap and heat shrink to at least minimize the wire’s presence outside of the canopy and frame.

First Flight-

Everything went completely against me  when it came time for the maiden flight. Between work, family and the weather it was over a week after finishing the build before I finally got the opportunity to fly the DT600. How sad is that? When I did get the opportunity it was a bit of a rush before dark one evening after work, so to be honest it wasn’t ideal maiden conditions. The first flight went off without any issue. There was however little doubt that I needed to do some tweaking to the settings in the flybarless controller.

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Finally the fun-

After getting the governor and flybarless unit mostly dialed in, it was time to get mentally connected to the model. The biggest surprise to me was the cyclic response and the overall nimble ability of the model. Playing around at 1900 RPM was a blast. It is light enough that I found this was a real pleasure and where I was flying 60% of the time. The rest of the time I was mixing it up between 2100 and 2300 RPM. At 2300 I found myself with a huge grin and the desire to throw the sticks hard just to watch the heli jump across the sky. After a minute or so I would have to catch my breath and go back to a lower headspeed and more precise flying.

 

Battery options-

DT recommends using a 12s system ranging from 2600 mah to 4000 mah. I am doing all of my testing with a 12s 3300 mah setup. This provides a solid 6 minute flight at 2300 RPM unless you are pegging the sticks for the entire flight. When I get an opportunity, I would like to do some low headspeed testing with two 3s 3000 mah batteries in series to create a 6s 3000 mah super low headspeed, crazy light weight 600. I’ll update when I get the chance for sure.

Headspeed options-

My current programmed headspeeds are 1900, 2100 & 2300 RPM. In coming testing I will begin to push the headspeed up closer to 2500, but the performance at this point is fantastic. There just isn’t a need to turn this into a 3½ minute machine by cranking up the headspeed, taxing your batteries and giving yourself the jitters.

Appearance-

The DT helicopters have a sleek look in my opinion. The stance is aggressive, yet not overly done. The canopy has a fairly pointed nose and clean wrap around look. This combines for an aerodynamic helicopter and is quite aesthetically pleasing.

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The vertical and horizontal tail fin are of simple and functional design. The vertical fin is long enough so that you don’t have to worry about damaging your tail blades on not so perfect landings. The landing skids seem to be a good mixture of some flex, but stiff enough so it should sag over time. The struts are a weird yellowish/white color. I would prefer black or white, but once the helicopter is assembled and the canopy is on, the color of the struts isn’t bad.

Head-

The DT600 uses a conventional 120° head design with the elevator in the rear. The anti-rotation bracket is also in the rear. Mine fit a little strange as it would tilt front to rear quite a bit. I chose where I thought it needed to be and snugged the screws up. This shouldn’t be a problem because there is not any front and back load on it, only side to side. The quality of the parts in the head was good overall. There were many sharp edges including the slot in the blade grips where the blades mount. Everything fit and moved very tight. Not so tight that I feel it is going to affect the performance as it seemed to have broken in well. The ball links are a strange spongy sort of plastic. When installing them they didn’t really “snap” into place. I used my ball link sizer to slightly enlarge the links going from the servos to the swash and that helped. The ball links between the swash and blade grips are an odd size. They were tight, so I had to just let them break in.

DT600_frame2.jpg

Maintenance-

It appears that this could be one of the easiest to work on 600 sized helicopters out right now. The frames are close together forming an amazingly rigid design. I cannot imagine what you would have to do in a crash to break them. Replacing the tail boom will likely take less than 15 minutes. Skids less than 10. If you have to replace a main shaft that will be around 15-20 minutes. Adjusting the belt tension takes a minute or two max. The bearings seem to be of good quality. Time will tell how they hold up. All of the servos can be accessed without having to remove anything to get to them.

Must be something bad…right?-

  • The ball links are in question. I will update the review once I see how well they break in and hold up.
  • The canopy on mine sits slightly off in the back. I don’t think it is really noticeable to others. It has also made some cracking sounds a few times when installing or removing although I cannot find any signs of damage.
  • The included battery straps were about 2″ too short to work for my 6s 3300 mah batteries.
  • Could have been a better solution for mounting the flybarless unit and receiver battery.
  • Prefer a battery tray for ease of use, but very difficult in a saddle pack configuration.
  • Short links between cyclic servos and swash cause a decent amount of interactions.
IMG_20131118_173215_589.jpg

Oh but the good!-

  • Great looks for sure!
  • Weight distribution is excellent on this heli. The motor and servos are directly in line with the tail boom. The batteries are just forward enough to balance the weight of the tail boom resulting in excellent cyclic response.
  • Herringbone main and pinion gear combined with belt drive tail make for a quiet flyer.
  • Canopy installation and removal is simple.
  • Building it was a breeze.
  • Maintenance should be extremely fast.
  • The canopy design, colors and scheme is very visible.
  • The frame design is extremely rigid.
  • PRICE!

Who should buy this?-

Isn’t this always THE question? The truth is there should always be several things someone looks at when purchasing their next heli…

  • Why do I want another heli?
  • Where am I going to fly it?
  • How much do I want to spend?
  • In what style do I plan to fly it?
  • What charging equipment do you have?

The reason I wanted to bring these up first is that I have often spoken with people that told me they were not satisfied with a certain helicopter. Every now and then I find out their helicopter was doomed before it ever had a chance, meaning that that particular helicopter just was not designed to do what they were trying to do with it.

In this case the DT600 is flat out a great helicopter from the beginner and first time builder, all the way to an experienced pilot. The fact that the parts and the kit itself is inexpensive is somewhat misleading to the quality of the kit and design. I would recommend this to anyone looking for a 600 sized helicopter. It is arguably good enough to compete at top level competitions. This will be determined once I can get some extremely hard flights on it, as well as more flights when I can feel exactly how precise it is.

Another user this would be great for is someone that wants a 600 that they can push themselves with, yet not be afraid of the cost if they crash. The cost of a typical crash is going to be cheap, cheap, cheap!  At the time of this review, DT600 blades are around $50, skids are $6, 2 tail booms are $10, 2 main shafts are $11 and 2 spindles are $5. So if you destroy all of that in a crash, you just crashed a 600 for $69. Holy crap!

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Final thoughts-

I should mention that I am very shallow hobbyist. I want my models to look as good as they fly. The polished aluminum combined with the nice black anodizing really brings out the looks in the model overall. They use this combination on the head and tail sections. Mix that in with a great looking canopy and you have a home run in the aesthetic department.

At the time of this review I’ve got almost 20 flights on it. I must say that my setup is a potent one. The motor has enough power to satisfy 90% of pilots. The light weight of the helicopter lends itself to lower headspeed flight with longer flight times. The HobbyWing HV 120 Pro isn’t even getting warm. I’m running about 13.5° of pitch and 10.5° of cyclic. If I really bury the collective I can bog the motor slightly, but tweaking the governor on the flybarless unit has almost eliminated that. Heck, who wants collective management anyway? With this power system there is not a need to purchase 65C batteries. My suggestion is to purchase between 30C to 45C batteries to save weight. Depending on your flying style you may be able to achieve enough performance with 25C, but please keep an eye on things if you are pushing it or flying in high ambient temperatures.

DT 4025-550 Motor

  • 550kv
  • 10 Poles
  • 50 mm diameter
  • 51.88 mm can length
  • 25 mm shaft length
  • 76.88 mm total length
  • 6 mm shaft diameter
  • 307 gram weight

KingMax KM-6917MDHV Brushless High Voltage Cyclic Servo

Dead band: 2μs
Control System:  +Pulse Width Control
Working frequence: 1520μs / 330hz
Operating Voltage:  DC6.0~8.4 V
Operating Temperature Range: -10 to + 60 degree
Operating Speed (6.0V): 0.11sec/60 degrees at no load
Operating Speed (7.4V): 0.09 sec/60 degrees at no load
Stall Torque (6.0V): 13.85 kg.cm (192.38 oz/in)
Stall Torque (7.4V): 17.52 kg.cm (243.35 oz/in)
Potentiometer Drive: Direct Drive
Dimensions: 40.5X20.2X40.2mm /1.59 X0.80X1.42 in
Weight:  73.60 g (2.60 oz)

KingMax KM-5308MDHV Brushless High Voltage Tail Servo

Dead band: 2μs
Control System:  +Pulse Width Control
Working frequence: 1520μs / 330hz
Operating Voltage:  DC6.0~8.4 V
Operating Temperature Range: -10 to + 600C
Operating Speed (6.0V): 0.051sec/60 degrees at no load
Operating Speed (7.4V): 0.035 sec/60 degrees at no load
Stall Torque (6.0V): 6.32 kg.cm (87.78 oz/in)
Stall Torque (7.4V): 8.53 kg.cm (118.48 oz/in)
Potentiometer Drive: Direct Drive
Dimensions: 40.5X20.2X40.2mm /1.59 X0.80X1.42 in
Weight:  53.00 g (1.87oz)

Videos

Here’s a video of Carter Reichardt “Carterizing™” the DT 600