Friday, August 11, 2017
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BK Designs: Switch Rotor Blades

This article was originally published in RC Heli Pilot December/January 2016 issue.
Words and Photos Dan Goldstein
050-1
The regular Switch blades look great and perform really well for a variety of flying styles. They can be very docile or handle more aggressive flight, but aren’t as biting as their XF counterparts.

Switch blades are a new contender in the vast blade market. What makes these blades unique is that they are being fielded by long-time pilot Bert Kammerer and his wife Suzie. Bert has always been intrigued by blade design and Suzie had been involved with V-Blades back in 2004. So, when the manufacturer Fun-Key approached Bert to author a new blade, he decided it was time to give it a go.

Bert drew on experience from previous brands of blades he’s flown and settled on a tried and true foundation mold design. He added his simple, graphic touch and the results were the Switch XF and non-XF series of blades. The XF is designed to be for the aggressive 3D pilot, where the non-XF offer similar performance, but are just slightly more sedate. All of the main blades have an integrated safety wire that runs from root to tip that helps prevent shattering on impact.050-2
Here you can easily see the graphics pattern with the non-XF blades. They have very good visibility against a dark background like a tree line or grass, but the white essentially disappears when up in a clear blue sky.

For the purpose of this review, Bert sent me a set of both versions (XF and non-XF) plus a set of 115mm tail blades to test back to back on my Thunder Tiger e700 V1 heli. My model is set up to be somewhat conservative with the capability of mild-3D. I programmed the ESC to run in SetRPM Governor mode with head speeds of 1500 and 1700. I also selected components to minimize overall weight. The best way to knock off weight entailed using MKS’s superb BLS line of plastic cased servos and 714g each Revolectrix Black Blend435 HV 30C LiPos.

I started by checking each set of blades with my digital scale and Koll Rotor Pro blade balancer. The non-XF blades weighed in at 203g and 202.7g each. One blade was heavy on the root side on the spanwise balance and required 0.6g of lead to correct. The chordwise balance was equal.

On the XF blades, both blades fell within 0.2 grams of each other at 200g overall. Spanwise, one blade was just slightly heavy on the root, but nearly perfect. On the chordwise balance, one blade was slightly heavy on the leading edge, but still had the level bubble just within the level marks. I didn’t apply any corrective lead weight to these blades.

The e700 outfitted airframe specs are as follows:
Motor: Hacker Turnado V3 A50-14L 400Kv, 10-poles
Pinion: 14T
ESC: Castle Creations Talon 120 HV, BEC @ 6VDC
Cyclic Servos: MKS BLS-970
Tail Servo: MKS BLS-980
Gyro: Spektrum AR7200BX
Transmitter: Spektrum DX9
Receiver: (2) DSMX Satellites
Telemetry: Spektrum TM1000 + Current/
Capacity Sensor by Christian Lagerhorn of Sweden
Main Rotor Blades: Switch 693 XF Carbon Fiber
Tail Rotor Blades: Switch 105mm Carbon Fiber
Battery: (2) Revolectrix Black Blend435HV 6S 5100mAH 30C LiPo
Model Weight (no batteries): 7 lbs. 2.8 oz.
Model Ready To Fly weight: 10 lbs. 5.1 oz.

AIR TIME

The non-XF blades tracked perfectly in a hover. In forward flight they felt smooth, cut through the air quietly and response was good. During aerobatics the blades reacted positively and without any gripes. Stops in tic- tocks were okay, but not as sharp as I’d prefer. Hurricanes tracked well and Autos were plenty good with lots of inertia, no let down given the size of this model.

The XF series blades performed similarly to the non-XF in all aspects except that their response felt a hint more crisp. Reaction to inputs also seemed more prompt and there was certainly more bite when pushed aggressively. In tic-tocks and rainbows the stops were more crisp and sharp. Tracking was still excellent throughout. Blade barking was more promi- nent on hard stops. They were very lively in flight and well mannered to boot.

FINAL THOUGHTS

Pilots who are looking for more scale like flying or who prefer sport aerobat- ics will find the non-XF blades perform exceptionally well. Those of you who fly aggressively, require your blades to be on point in all maneuvers and enjoy blade barking should go for the XF series. The price is the same for either version, so the choice is purely about what meets the needs of your flying style.

Bert has championed many great products in his RC heli career so far and these blades deliver yet another satisfying experience. There are more exciting blades coming from BK, along with night versions of the popular sizes.

CONTACT

BK DESIGNS bkdesignsllc.com

 

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