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Old Nov 27, 2008, 12:51 AM
unlicensed helicopter nut
zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
Mini-HowTo
Blade CP Pro - brushless tail mod

The Blade CP Pro flies like a dream with a brushless tail motor. I always enjoy flying it and have tried stronger brushed motors and a dual motor tail to overcome the primary flaw in its design. My Blade already had a Park 370 brushless motor. Recently I switched to a Turnigy Plush 18 amp ESC that made this motor run smoother, cooler, and it seems also faster, than the controller I got from E-flite. While I was installing the BM in the tail I also switched from rubber dampers to ball bearings in the rotor head, a la Kyle Stacy. The main blades track more accurately and fly smoother.

Components:

Small brushless motor, ESC, separate gyro (may as well be HH) one extra length of wire to the tail, heat shrink tubing, 3" or 4" propellor.

I bought a 10 gram 2000 kv outrunner BM from Hobby-city.com and a Turnigy Plush 10 amp ESC. These components are very light, inexpensive, and work well. The ESC is easy to program and comes with complete and accurate directions for doing so. I bought both of them from www.Hobby-city.com

Motor: 18-11 2000kv Micro Brushless Outrunner (10g) [on back order as of 12/12/08]

ESC: TURNIGY Plush 10amp 9gram Speed Controller

Mechanics

I modified the Blade's plastic tail motor case to accept the motor. This meant enlarging the center hole and making two small holes in the sides to pass screws to the motor's base. I also made a channel on the rotor side to accommodate the wires from the motor.
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Old Nov 27, 2008, 12:54 AM
unlicensed helicopter nut
zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
Brushless Tail Mod - continued

Electronics

Using a brushless motor means using a separate gyro. This lets us say bye-bye to the 3-in-1, a welcome weight savings to offset the additional weight of the gyro and ESC. After removing the mixing board I turned the receiver on its side. The glitching that occurred every time I flew (so used to it I didn't care) has gone away. The existing Park 370 BM is controlled by a Turnigy Plush 18 amp ESC (which runs the motor more smoothly than the E-flite unit did); both ESC's are mounted below the main gear using the CF rods and an extra battery tray.

Wires from the smaller ESC run inside the tail boom. Believe it or not it is easier to push three wires through it than two because there is no room for them to kink. I decided to solder the connections to and from the tail motor's ESC. I soldered all three with heat shrink tubing to the wires at the frame. At the tail I completed the heat shrink process on one wire and left the tubing alone on the other two until I verified that the 4040 propellor was pushing in the correct direction. The lead from the ESC to the gyro has three wires. The center red wire should be removed (see gyro picture below) from the plug by pushing an X-acto blade under its keeper while pulling gently on the wire. On the power side I soldered the red and black leads direction to the wires to the JST plug that mates with my batteries. Power leads from both ESC's meet on these leads.
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Old Nov 27, 2008, 12:55 AM
unlicensed helicopter nut
zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
Brushless Tail Mod - continued

Programming

On my heli the tail motor kept spinning after the left stick was lowered all the way. I had to keep the left stick all the way to the left to stop the tail rotor until I could get a hand on the tail boom. Then, letting go of the Tx, the motor went back to spinning until I unplugged flight power. So I had to program the Tx using programmable mixing. This cannot be done with the stock E-flite transmitter.

In this form of mixing one channel is slaved to another channel. I defined channel 3 (throttle) as the master and channel 4 (rudder) as the slave. I then defined the slave as -50% (just to be sure) when the throttle was at 0% in normal mode. In other words the tail motor is off when the left stick is down. In theory setting channel 4 to 0% would be enough but I don't want there to be any chance of the tail spinning up when the main motor stops.

Next came setting sub-trim on the rudder channel to get the tail to stay in one place. Mine is set to -52%. It may need this much sub-trim because I have a 4" propellor on the tail. I understand most guys use 3" or 3.5" props. In any case, the tail is so solid that I can set the throttle to hover and fly the helicopter with my right hand only.

Last comes gyro gain. At this writing it is set to 65% and the tail still wags a trifle. I am having a lot of fun gradually dialing it in!

Flight test

After hovering inside to set the programming as described I took the helicopter to the park on a dead-calm morning. It flew quiet, stable, and more controllable than ever. I had been flying with the rate gyro on the mixing board and a dual tail motor set up. Recently I crashed in a stall turn because instead of swinging 180 degrees the heli went into a piroette and came down more strangely than I was ready to deal with. During the test flight the tail swung smartly around and stopped in the correct orientation. With the right modifications the Blade CP Pro can fly like a little Trex.

Blade CP Pro with brushless main and tail motors (2 min 34 sec)
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Old Nov 27, 2008, 01:49 PM
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Brown Shoe's Avatar
Northern Cali
Joined Sep 2003
1,327 Posts
Question? Isn't the guage of the wires gioing down the boom too thin?
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Old Nov 27, 2008, 02:43 PM
unlicensed helicopter nut
zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
The stock gauge wires are just fine for the BM in the tail. According to estarter, who knows a thing or two about electronics, the 10 gram BM uses less power than the stock tail motor. I just took a damaged tail wire/JST plug assembly and clipped off the full-length good black lead to give myself three wires between the ESC slung under the main gear and the tail motor.

BTW: I used two-and-a-half layers of double-sided servo tape to secure the HH gyro over the zip ties holding my quick change tail boom onto the gyro mounting platform.

I just got back from flying on turkey day. Managed a few nose-in funnels and backwards circuits, courtesy of indoor practice with the Honey Bee FP! Anything you can do with the Honey Bee you can do with the Blade easier once the tail is set up to hold properly.
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Old Nov 27, 2008, 07:10 PM
Registered User
Berkeley, CA
Joined Oct 2004
1,895 Posts
Well done Zen, make sure you insulate the connector (+5V) in the red wire hanging out from the gyro in the right pic.
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Old Nov 27, 2008, 08:13 PM
Test Pilot, Stand Clear
eatmydirt's Avatar
USA, OH, Mt Vernon
Joined Mar 2007
1,371 Posts
Are you flying it with the 1000 mAh lipo? I thought you said it was too heavy for CG?

Anyway I might copy your tail set up, if I can get around to it. I like your CPP and I have a few to play with.
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Old Nov 27, 2008, 09:05 PM
unlicensed helicopter nut
zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
Yes, the 1000 mah batteries are a trifle heavy but you know how it is when you want to get in the air..... Plus I went back to the CF battery tray rods so now I can adjust the CG by moving the battery back. Before now I have been sticking batteries to velcro loops under the shelf that holds the Rx and 3-in-1.
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Old Nov 28, 2008, 06:28 AM
Registered User
Joined Oct 2008
19 Posts
Still having problems with my setup. Seems like the e90 gyro is not holding properly (I set above 50% gain for HH mode), and upon lift off (and right before) the heli wants to jump to the left wildly, tail all over the place. I know my gyro is working cause when I yaw it quickly in my hand it counters the yaw correctly and quickly, but getting into a hover (which is almost impossible right now) the tail just wants to do whatever. I have tried many different gain settings to no avail. I guess it could be something with the head setup. I have all cnc microheli and eflite head parts, so everything is smooth and barley any play. Also I have a microheli one way auto gear.

I know when I put my 8t pinion on th e370 park motor, it might not have been super precisely straight/flat with the end of the motor shaft. I cannot see this minute fraction of a mm off with the pinion causing the heli to veer off this much, yes it could have a vibration for sure, but no vibration yet. Maybe its time to look at the head set closer, mechanically and Tx programing wise. Yes I also have set my servos 90 degrees at mid stick, blade pitch is 11 and -11, blades track perfect, this is a brand new setup never been crashed (not yet).
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Old Nov 28, 2008, 10:11 AM
Registered User
Toronto Canada
Joined Dec 2002
5,367 Posts
Quote:
Originally Posted by NewbieNewb
(I set above 50% gain for HH mode)
How are you setting the gain?

On the gyro or on the transmitter?

Setting the gain above 50% using the pot on the gyro does NOT put the gyro into HH mode.

The gain setting on the gyro has nothing to do with the mode setting.

The reason that I mention this is that if you are setting the gain using the pot on the gyro, you have the full range which you can use to adjust the gyro, not just the upper 50%.

Perhaps your gyro setting is simply set too high.
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Old Nov 28, 2008, 10:52 AM
unlicensed helicopter nut
zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
NewbieNewb— are you using a brushless tail motor? If so did you use programmable mixing to stop the tail rotor from turning when the left stick is all the way down?
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Old Nov 28, 2008, 12:07 PM
Low rates are for wimps
bwoollia's Avatar
United States, CO, Colorado Springs
Joined May 2008
3,251 Posts
It doesn't make sense that you would have to do any programming to keep the tail straight using HH mode - by definition, a HH gyro will make inputs to the tail servo (or ESC in your case) to eliminate any yawing movement. Any mixing from the radio should be counterproductive, instructing the gyro to make inputs until the tail moves.

I'm about to start a similar project and was looking at motors with higher kv - how is the response of this motor? In particular, how much lag until the tail starts to move, and how quickly can it yaw to the right?

Nice work!
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Old Nov 28, 2008, 01:28 PM
unlicensed helicopter nut
zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
Quote:
Originally Posted by bwoollia
It doesn't make sense that you would have to do any programming to keep the tail straight using HH mode ...

... how is the response of this motor? In particular, how much lag until the tail starts to move, and how quickly can it yaw to the right?

Nice work!
And yet it does require progamming on my helicopter. As I said above, I suspect the 4" propellor is cranking out more thrust than I really need. If sub-trim is at zero the tail drifts to the left.

Speaking of tail thrust it promptly yaws right. There is no lag that I am aware of. Not that I'm a hot shot pilot....
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Old Nov 28, 2008, 01:45 PM
Low rates are for wimps
bwoollia's Avatar
United States, CO, Colorado Springs
Joined May 2008
3,251 Posts
Perhaps this setup may end up on my CP! As it stands right now, the 3 in 1 is just a very heavy speed controller for the brushed tail motor.
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Old Nov 28, 2008, 02:04 PM
roscoedude's Avatar
United States, OH, Cuyahoga Falls
Joined Oct 2006
789 Posts
Nice work zen, these heli's really wake up with the BL set-up, I tend to fly mine more now (since going BL) than ever, great fun .
Good tip about the sub-trim for the tail, not alot of people know about that or are willing to tell.

Keep up the good work.
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