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KDS Agile 7.2 700-Size Electric Helicopter Review

KDS's latest 700-size model flouts high quality, high visibility and high performance!

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Introduction:

My first experience with KDS was several years ago when they released their Innova line of model helicopters. They didn't have any distributors in the USA at the time. I was sent their Innova 450SD and later, a Innova 550 to evaluate. They were decent models, but were constructed of low grade materials. Towards the end of my evaluation period, a friend of mine who was positioning to be a distributor told me that KDS was working on a new model with much higher quality materials and a more competitive design.

The new proto-type model, designed by Roberto Gaziano of Belgium was being fielded by KDS's team pilot Jaehong Lee at the 2012 3Dx China. I saw several pictures of the model and it looked pretty beefy and read heavy. Several months later the line was branded as the Agile series and a while after that a US distributor was established in Texas. The Agile line opened with two models, a 550-size named the Agile 5.5 and the 700-size Agile 7.2.

I received the Agile 7.2 from Roberto for this review and some technical assistance from KDS Models USA.

Model Specifications:

  • Length: 1370mm
  • Height; 420mm
  • Width: 200mm
  • Main Rotor Diameter: 1560mm
  • Main Blade Length: 690-713mm
  • Tail Rotor Diameter: 294mm
  • Tail Blade Length: 105-115mm
  • Motor Pinion: 19T
  • Suggested Motor KV: 500-540KV
  • Driving Gear: (19/54)(20/66)
  • Gear Ratio: 19T (9.37:1)
  • Tail Gear Ratio: 4.75:1
  • Weight(w/o power): 9 lbs 7.5 oz. / 4294.95 g
  • Flying Weight: 13 lbs 0.5 oz. / 5910.87 g
  • Suggested Battery: 22.2V 5000mAh x2
  • Suggested ESC: 12-14s 160-200A

Build Overview & Tips:

The model was well packaged and the more substantial aluminum parts were snugly held in dense foam trays. The finish on the parts was very high quality and while beefy, they weren't heavy at all.

The build started with the battery mounting tray. There were aluminum stand-offs that fit precisely into the mounting holes of the tray. It was a tight fit, so to insure I properly installed them, I set the plate flat on a granite block and carefully and lightly tapped one set of stand-offs into the holes until they were flush. Once installed, I applied thread lock to the studs and then threaded the opposite side stand-offs onto the studs and snugged them down.

After installing the main belt drive gear onto the shaft I found it to still be a bit loose. I reached out to the distributor and was instructed to keep tightening the M4 screw and nut until the play was gone. I had to really crank down on the screw to eliminate the play.

The head dampening was very tight and made assembling the head a bit arduous. I used DuPont Krytox grease on the dampers and spindle. I used a mallet to tap the spindle into the dampers and through the head block.

I used DryFluids Gear lube on the main grip thrust bearings. A thin layer was all I needed and it won't sling out like traditional grease. I also used this lube on all of the gearing to keep the friction down and efficiency up. KDS includes shims for taking up play in the head, but out of the box none were needed since the movement was slop free and smooth.

When I assembled the upper bearing blocks, the main shaft wasn't dropping through the 3rd bearing block. Unfortunately, since the 3rd bearing block essentially locks the frames together, I had to carefully elongate the six M3 holes for the top bearing block just enough to allow the main shaft to drop through without any resistance.

I installed the motor as per the manual, but wasn't getting the correct tension or alignment. Again, the distributor advised me to first apply as much pressure as I could by hand to tighten the counter bearing block first, tighten the screws down for that and then firmly pull on the motor to tighten the top part of the belt. After getting the belt tight, I double checked the belt alignment on the main drive pulley, and I had a perfect 0.5mm of exposed teeth on the top and bottom.

Another key tip I learned from the distributor was that the 10mm x 15mm washer depicted on page 17 of the manual should NOT be installed during the initial built. It's meant to be used to take up potential play in the drive-train after 100+ flights. If you were to install it now, it would apply a unhealthy preload on the drive-train and radial bearings in the bearing blocks.

I used more DryFLuids Gear lube on the tail grip thrust bearings. Since it dries into a slippery film, there isn't any chance of it slinging out in flight or causing a dry bearing failure.

Assembling the torque tube was a little tricky. I installed the bearings onto the shaft and kept them in place by wrapping a bit of Scotch tape on either side of each bearing. Then I sanded the surface of the ends of the tube, lathered on some JB Weld epoxy. Next, I pushed the plastic torque tube coupler on and aligned the retaining pin holes. I had to carefully support the narrow shank of each plastic torque tube coupler with the edge of my granite block. I used a set of pliers to place the pin at the opening of the coupler and used a hard rubber mallet to tap it in. It was a really tight fit and I thought there was a chance the coupler might crack, but it all worked out fine.

The next hurdle was getting the torque tube into the tail boom. I had to use a combination of the Krytox grease, WD40 and a spare carbon fiber pushrod I had laying around to push each bearing support into the boom. After the arduous assembly, I put it aside to let the JB Weld dry overnight.

The manual's sequence of assembly is a bit weird about the torque tube and installation of the tail boom into the frame. It seems page 24 and 25 should be swapped. You install the torque tube into the boom, slide on the push rod guides and tail boom support bracket. Then add the tail case assembly with vertical tail fin bracket and front torque tube drive dog-bone assembly. Next, slide on the plastic frame mounting blocks and insert the two M3 cap head screws with medium strength threadlock into the the side of the front block and tighten into the bearing block.

When I was assembling the tail boom braces the included Allen set screws were not the M2.5 size as indicated in the manual. Unfortunately, the key needed was not included in the kit and when I found one in my own stash that did fit, it quickly stripped in the process of trying to drive the screw. I wound up drilling out the holes a bit and installing M2 cap head screws.

I noticed lateral play in the main rotor head yoke during installation of the main rotor head to the main shaft. Likewise to my experience with the main drive gear, I had to crank down on the two M4 screws to get the yoke to clamp tightly onto the main shaft. Once the screws were super tight, the play was gone.

Wiring up the iKon flybarless controller was a bit challenging due to the tray location. I had to position it with the wires exiting towards the main shaft. I carefully dressed the wires away from the shaft and protected them from the carbon frame edges. I wound up running the cyclic servo wires on the outside of the frame to shorten the run to the gyro.

I mounted the Castle BEC under the ESC mounting plate. I bundled the excess wire, shrink wrapped it and tucked it along side the BEC for a clean look. I put the receiver on the carbon plate at the rear of the frame. The antennas were clear to run in the open air out the back of the frame.

How does it fly?:

Hovering:

The Agile sat solidly in wind and barely needed any corrections to keep it steady. It's certainly on par with nearly every other 700 I've had, though with the belt drive, the Agile is quiet and feels smooth. Ascent and descent during wind gusts was minimal and easily mitigated with a smidgen of collective.

Forward Flight:

Locked in! The Agile tracks perfectly, quietly and fast! Loops, rolls and general aerobatic flight felt smooth, tight, well balanced and effortless. It certainly felt more like a F3C machine than a bonkers 3D smack animal. The aerobatics were perfectly mannered at 1750 on the head, and as expected, more lively at 1900.

3D:

This model is fantastic at performing 3D in a smooth manner. It belted out smack-like 3D at 1900 without a hitch. The head dampening was working great and allowed the gyro to produce crisp stops with no wobble. Piros were fast and again stops were crisp and solid. Dropping down to 1750, the model grooved in big air 3D. Hurricanes locked in easy and tic-tocks were still tight and fun at the lower head speed. The over all feel of the model was locked in with no weird gremlins or poor tendencies.

Autorotations:

With 710mm blades the model floated really well. The transmission system was super efficient and minimized drag when I hit hold. Aerobatic autos were no sweat and I was still left with a decent amount of blade inertia to soften my landings.

Impression:

ProsCons
Precision fit partsMinor errors in manual
Quality materialsAssembly issues with tail brace collars and allen screws
Smooth and quiet flyingProper main shaft alignment required bearing block mounting holes to be elongated

The Agile 7.2 is a great quality model and looks and feels nothing like the preceding Innova line. The assembly had a few hitches, but I was able to work through them and experience excellent results. My flights felt great, the model handled like a well tuned race car and gave me fantastic flights time that averaged around 6 minutes.

The Flight Video ...

KDS Agile 7.2 Radio Control Helicopter Flight (4 min 25 sec)

Components Used:

Downloads

Manual_Agile_72  1.50 MB

Picture Gallery

Last edited by Angela H; Jan 29, 2015 at 05:18 PM..

Discussion

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Old Jan 30, 2015, 02:14 PM
Registered User
missle's Avatar
West Chester, Ohio
Joined Nov 2006
1,724 Posts
Awesome job with the review and some great flying. It's nice that you did slow flight so that us old folks can actually see what's happening.
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Old Jan 30, 2015, 03:11 PM
AMA# 548800
jombo's Avatar
United States, CT, Trumbull
Joined Dec 2007
5,477 Posts
Ok , I have to say the words you said in the build , who am I kidding . I went right to the video . That thing was awesome . Where did you have the microphone ? On the helecopter . Very nice sound from it , no music just the motor and blades ! Classic!
Great job , and the sigh of relief at the end love it . Great flying
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Old Jan 31, 2015, 03:29 AM View Post
doriaqi7
A moderator felt this post violated the following rule: Off Topic Advertisement. Show it to me anyway.
Old Jan 31, 2015, 08:55 AM
MassiveOverkill's Avatar
United States, FL, Melbourne
Joined Feb 2011
5,777 Posts
Check out Jordan's nighttime LED competition vid:

KDS Agile 7.2 EXTREME Night Flight Pilot: Jordan Horwitz (2 min 46 sec)
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Old Feb 02, 2015, 03:03 PM
Mulit-Platform Pilot
barracudahockey's Avatar
United States, FL, Jacksonville
Joined Sep 2004
3,803 Posts
Nice job Dan!
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Old Feb 02, 2015, 03:07 PM
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darkfa8's Avatar
United States, NJ, Brick
Joined Jul 2005
129 Posts
Thanks everyone!
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Old Feb 26, 2015, 08:03 AM
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darkfa8's Avatar
United States, NJ, Brick
Joined Jul 2005
129 Posts
Dry Fluids

For reference, the link to the lubricants I used is:

http://dry-fluids.com/dryfluids-english.html

- Dry Fluids Heli for shafts and radial bearings

- Dry Fluids Grease for gearing, push rod guides and thrust bearings
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Old Feb 28, 2015, 06:07 PM
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(double post)
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Last edited by Atomic Skull; Yesterday at 12:38 AM.
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Old Feb 28, 2015, 06:12 PM
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Atomic Skull's Avatar
Joined Dec 2011
3,576 Posts
Somthing that I rarely seen mentioned about KDS tail grips is that with the latest iteration you can brinnel the tail grip bearings if you over tighten the nylock nuts. The old version could be fully tightened and would still have some axial play, the new version are like Kasama grips, you're supposed to tighten them till the axial play is gone and no more.

It seems to me that running tail grips with a nut that isn't fully tightened would be a bad idea, but Kasama has used grips like that for over a decade so it must work ok.

FYI they do sell a replacement top part for the "traditional FBL" version of the swashplate.
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