Blade CX for those to talk about

[Rodono]

Hi Bry;
Dacaur's BCX website might help.
www.dacaur.com/bladecxhelp.html
The BCX dissassembly pdf and the BCX Mods Word document shows how it should go back together and a tip on aligning the parts respectively.

[uglyplane]

Originally Posted by MMCGinnis

I have not done this yet, but I am looking for a couple of surface mount or otherwise miniature ~5amp fuses to solder inline with the motor leads to protect this MOSFET from being fried again. It would be MUCH easier to replace the fuse than to replace the MOSFET again. Besides, this board can only take so much heat before you have nothing left to solder to. When I find the appropriate fuses and complete the next surgery, I’ll fill everybody in on how to do it.

I hope someone finds this info useful.

Matthew McGinnis

Great info Matthew! I read this post on RCG and just acquired a BCX yesterday. Did you ever try the fuse experiment? I would be interested in doing it as well....

Bill

[uglyplane]

Any more bling for the BCX out there? I bougght one yesterday, along with the heat sink and alum rotor head. I'm wondering if anyone found a drop in replacement higher quality brushed motor for it. I'm going to do the canopy/4 in 1 cooling mods tonight and maybe the black marker on the motor cans too.

Anyone have a feel for how long the motor and gears last? I have a XRB as well, but I find the BCX to be more responsive and parts to be more affordable. I like the fact that it uses regular servos too...

[PHIL I.]

Someone adapted 2 outrunners & 2 ESC's & an RX. From who I don;t know. He already had a programable TX to work with it..Sorry but a little too hi $$$ for me...
Motors are so cheep and you will have to really fly a
lot to wear one out....

PHIL I.

[twohats]

I am new here and new to helo,s. Picked up the bcx 2 weeks ago and love it. After the wind quits in the evenings I head out to the local empty lot to fly and this thing does fly. Have the upper fly bar hub up grade and heat sink.But what this realy needs is a stiffer lower rotor blades that dont flex up when giving it power when trying to fly into a slight breeze. But this thing is a blast.

[MMCGinnis]

Glad to hear my info helped you. I would be very interested in your calculations. Here are my measurements/calculations:

The average flight time on an 800mAh battery is 10 minutes. That is the equivalent of 4800 mAh or 4.8 Amps running amps over an hours time. Since the two motors pull 99% of the current, we can assume that each of the two motors pull half that or 2.4 Amps each while running. I measured about 3.8 volts across each motor at hover and 4.65 volts near maximum power. Using an average of 4 volts:

Current * volts = power or 2.4A * 4V = 9.6 watts for each motor while flying.

I measured between .5 -1.0 ohms across the motor windings depending at what point in the motors rotation I measured (If brushes were contacting two windings at once, I measured .5 ohm, if 1 winding was contacting, I measured 1 ohm.). This means that the current could approach 8 Amps (4 volts / .5 Ohms) each or 16 Amps through the dual HEXFET, Which BTW is only rated at 6.5 total constant amps. That would be closer to 64 watts (16 Amps * 4 volts) dissipated by the HEXFET under the worst case (2 windings in contact with the brushes). Your calculations of 26.4 watts radiated by the HEXFET seems real close to mine if you were calculating only one winding being touched by the brushes at the time of rotor stall (I calculated 32 watts). BTW if this HEXFET radiates 64 watts, at the size of .15 inch by .19 inch, if this device were 1 square inch, it would be radiating 2240 watts---quite toasty I must say.

I originally installed 3 amp inline fuses with my motors, expecting them to blow easily. I did get one of the fuses to fail after pushing three 800 mAh batteries through my CX with moderate flight. (I'm not that good yet to be aggressive). Half way through the third battery, for no apparent reason, the CX began a not so graceful pirouette to the basement floor. The upper blade motor fuse had failed. I've since replaced them with 4 Amp fuses and have yet to blow one. I have not intentionally stalled the blades to see which will go first, the HEXFET or the fuse, but I do feel confident, however, that the fuse will work. If I ever get into a crash and stall the blade, I'll let everyone know the outcome.

FYI, the fuse I am using is a LittleFuse 4 Amp PICO fuse PN# 0251004

Here is the web page for the fuse:

http://www.littlefuse.com/cgi-bin/r.cgi/en/prod_parts.html?PartID=4370&LFSESSION=mBiUUxCNx4


I simply soldered the fuses inline with one lead on each motor. Careful not to allow too much heat from your soldering iron to reach the fuse core, at it may weaken or blow the fuse before you even get off the ground. I left a long amount of lead on each end of the fuse to help in isolating the iron’s heat from the fuse. These fuses are TINY, about the size of a 1/8 or ¼ watt resistor.

Another alternative, is to install the fuse holder (as seen in the web page above) inline with the motor leads. Then, when the fuse blows, just pull out the old fuse and replace it. I opted against this, as I didn’t see the need to add the extra weight, though nominal.


-----"bolo_invictus @ Radio Control Zone" wrote: -----
Date: 08/20/2006 04:13PM
Subject: Blade CX

This is a message from bolo_invictus at Radio Control Zone ( http://forums.radiocontrolzone.com/index.php). The Radio Control Zone owners cannot accept any responsibility for the contents of the email.

This is the message:

Thank you!!!! Your thread dated last April titled: "How to repair a blown 4-in-1 Blade CX controller" really helped. I have never seen a part get so hot that it unsoldered itself from the PC board as mine did. I could not identify the IOR part number from the charred remains. I've since traced out the controller circuit and made some measurements of the locked rotor current and voltage for one of the motors. The moment both rotors lock, the pass element dissipates 26.4 W!! No amount of ventillation will prevent the part from incinerating. I'll email you the details. I'd like to hear if your fuse idea worked.

thanks,

brian connolly

[jltray]

I use fuses in my airplanes. The draw back with using one on a heli is if the fuse blows you loose lift which results in a fall object from the sky.

I would agree that if you push the power full on from the ground to get a fast climb it will blow the MOSFET as I have today. I have had my Blade CX for 5 days, about 5-6 flights and now it's toast. I'm going to try to swap it at the hobby store and install fuses myself.

Thanks for the information

jimmy

[jltray]

Did you use the mini barrel fused or small automotive?

Jimmy

Originally Posted by MMCGinnis

Glad to hear my info helped you. I would be very interested in your calculations. Here are my measurements/calculations:

The average flight time on an 800mAh battery is 10 minutes. That is the equivalent of 4800 mAh or 4.8 Amps running amps over an hours time. Since the two motors pull 99% of the current, we can assume that each of the two motors pull half that or 2.4 Amps each while running. I measured about 3.8 volts across each motor at hover and 4.65 volts near maximum power. Using an average of 4 volts:

Current * volts = power or 2.4A * 4V = 9.6 watts for each motor while flying.

I measured between .5 -1.0 ohms across the motor windings depending at what point in the motors rotation I measured (If brushes were contacting two windings at once, I measured .5 ohm, if 1 winding was contacting, I measured 1 ohm.). This means that the current could approach 8 Amps (4 volts / .5 Ohms) each or 16 Amps through the dual HEXFET, Which BTW is only rated at 6.5 total constant amps. That would be closer to 64 watts (16 Amps * 4 volts) dissipated by the HEXFET under the worst case (2 windings in contact with the brushes). Your calculations of 26.4 watts radiated by the HEXFET seems real close to mine if you were calculating only one winding being touched by the brushes at the time of rotor stall (I calculated 32 watts). BTW if this HEXFET radiates 64 watts, at the size of .15 inch by .19 inch, if this device were 1 square inch, it would be radiating 2240 watts---quite toasty I must say.

I originally installed 3 amp inline fuses with my motors, expecting them to blow easily. I did get one of the fuses to fail after pushing three 800 mAh batteries through my CX with moderate flight. (I'm not that good yet to be aggressive). Half way through the third battery, for no apparent reason, the CX began a not so graceful pirouette to the basement floor. The upper blade motor fuse had failed. I've since replaced them with 4 Amp fuses and have yet to blow one. I have not intentionally stalled the blades to see which will go first, the HEXFET or the fuse, but I do feel confident, however, that the fuse will work. If I ever get into a crash and stall the blade, I'll let everyone know the outcome.

FYI, the fuse I am using is a LittleFuse 4 Amp PICO fuse PN# 0251004

Here is the web page for the fuse:

http://www.littlefuse.com/cgi-bin/r.cgi/en/prod_parts.html?PartID=4370&LFSESSION=mBiUUxCNx4


I simply soldered the fuses inline with one lead on each motor. Careful not to allow too much heat from your soldering iron to reach the fuse core, at it may weaken or blow the fuse before you even get off the ground. I left a long amount of lead on each end of the fuse to help in isolating the iron’s heat from the fuse. These fuses are TINY, about the size of a 1/8 or ¼ watt resistor.

Another alternative, is to install the fuse holder (as seen in the web page above) inline with the motor leads. Then, when the fuse blows, just pull out the old fuse and replace it. I opted against this, as I didn’t see the need to add the extra weight, though nominal.


-----"bolo_invictus @ Radio Control Zone" wrote: -----
Date: 08/20/2006 04:13PM
Subject: Blade CX

This is a message from bolo_invictus at Radio Control Zone ( http://forums.radiocontrolzone.com/index.php). The Radio Control Zone owners cannot accept any responsibility for the contents of the email.

This is the message:

Thank you!!!! Your thread dated last April titled: "How to repair a blown 4-in-1 Blade CX controller" really helped. I have never seen a part get so hot that it unsoldered itself from the PC board as mine did. I could not identify the IOR part number from the charred remains. I've since traced out the controller circuit and made some measurements of the locked rotor current and voltage for one of the motors. The moment both rotors lock, the pass element dissipates 26.4 W!! No amount of ventillation will prevent the part from incinerating. I'll email you the details. I'd like to hear if your fuse idea worked.

thanks,

brian connolly

[MMCGinnis]

I used what is known as a PICO fuse. It looks almost exactly like a 1/8 watt resistor. It is about 1.5 mm in diameter and about 3-4 mm long with the leads comming off either end like a resistor does. I got then from www.littlefuse.com. Check my post above for the link to the exact fuse.

[jltray]

Very cool. I forgot all about them. I see them on circuit boards in some of our equipment.

Good find, thanks

Jimmy

[jltray]

I'm working on some documents that I will post on my site about tweaking, repairing and maintenance of the Blade CX.

If anyone would like to contribute, please email me rc@traylorhead.com

Jimmy

[boardmaster84]

hi im new to this. i have the blade cx and im having a problem with it and i need help. the top blades of the heli continue to spin at a constent rate and i cant change the speed. Can u help? or do u have and sujestions?

[boardmaster84]

Originally Posted by zappedalaskan

I just ordered a Blade cx from Wills Hobby and CB shop. (AKA debhicks)
Top notch customer service and on-line support right here! Can't beat that. New Blade cx owners please feel free to stop in often and post your experiences. Or any questions you might have about the Blade cx.
Take care,
Jay

hi im new to this. i have the blade cx and im having a problem with it and i need help. the top blades of the heli continue to spin at a constent rate and i cant change the speed. Can u help? or do u have and sujestions?

[UncleBob]

I liked mine except the swashplate assy was always seperating. Is this typical? Is there a fix? I stopped flying it and went to a BCPP because of this issue.

[MMCGinnis]

All ya gotta do to fix the seperating swashplate issue is put a thin coat of CA glue (super glue) on the outter edge of the bearing and quickly shove it into the swashplate housing. It'll never come out again. Careful not to get so much that the glue gets into the bearing. That'll trash it for sure.

Originally Posted by UncleBob

I liked mine except the swashplate assy was always seperating. Is this typical? Is there a fix? I stopped flying it and went to a BCPP because of this issue.

[MMCGinnis]

Chances are, your HEXFET is shorted on your 4-in-1 unit. Usually the burn open, but I've seen them short as well. I reccommend following my previous proceedure to replace the HEXFET chip and see what that does.

Good luck..

Originally Posted by boardmaster84

hi im new to this. i have the blade cx and im having a problem with it and i need help. the top blades of the heli continue to spin at a constent rate and i cant change the speed. Can u help? or do u have and sujestions?

[jermo]

With the replacement of the MOSFET on the 4 In 1 unit would it make more sense to mount it somewhere else besides the rx board? Consider that the heat from the MOSFET is one of the main reason's the Gyro drifts. I would think that we could mount it externally on a heatsink and just use cables to connect. This would make it more like bigger heli's with an external ESC. That would allow us to potentially have a seperate board to solder/mount fuses..etc to. We could jumper the connections intended to go TO the MOSFET to the normal connections for the motors on the RX and add pigtails to our new ESC with female connectors that connect to the motors.

The desired end result is a cheap solid fix for the heat induced tail drift issues.
Jermo

[jermo]

Originally Posted by MMCGinnis

The average flight time on an 800mAh battery is 10 minutes. That is the equivalent of 4800 mAh or 4.8 Amps running amps over an hours time. Since the two motors pull 99% of the current, we can assume that each of the two motors pull half that or 2.4 Amps each while running. I measured about 3.8 volts across each motor at hover and 4.65 volts near maximum power. Using an average of 4 volts:

Current * volts = power or 2.4A * 4V = 9.6 watts for each motor while flying.

According to the spec sheet the unit is only engineered to handle 2W Dissipation at 25 degrees C through the device and a junction Dissipation of 62.5 C/W. Reading further these are only good for <= 10 seconds for a surface mount component.

I'll work on the external design as I get time. It all depends on what HH does with my BCX.
Jermo

[Monty]

Jltray: Can you point me to instructions on mounting a MOSFET heat sink? It sounds like a very good idea, correcting the heat induced gyro drift will make my CX2 even better; not to mention protecting the MOSFET and other Rx parts from the heat...

[jermo]

Basically there's 2 ways to do it. One is easy the other is better. Buy a small heat sink that's used in video card cooling sets to cool video ram (you can get these in sets of 8 generally). They come with a heat conductive adhesive. locate the mosfet on the board, put the RX cover back on and mark the center of the chip. Remove the RX cover adn Drill/cut a hole large enough for the heatsink to protrude from the case. Install the case and verify alignment of the heatsink. Install the heatsink.

I've not tested this method yet but plan to. I'll have to cover my RX case to close all the cooling holes I've added. The purpose of the heatsink is to move the heat away from the inside of the case AND help keep the mosfet cooler. I expect we'll still need to ventillate the canopy to provide airflow.
Jermo

[Buzzkill]

What do you guys think of an adjustable nose weight? I installed a S60 the other day for a landing light that I could swing up 90 degrees when flying forward and back down for landings (looked really cool flying in the down position with the police body, reminded me of the TV show Cops when the Helis have their search lights on looking for perps) anyway it would be real easy to keep the servo arm inside the body with a weight that that would be centered in the up or down position and swung forward to shift the weight to the nose via the 5th channel knob. I've never tried a nose weight for forward flight but I've seen a few post saying it helps alot. I know the weight would slightly decrease flight times but wat the heck. By the way, the e-flight S60 didnt do anything to my flight times or unbalance the heli that I noticed.

I thought of maybe instaling a tail fin that could be adjusted to pitch the tail for forward flight. Dont know if anyone has tried these if you have let me know how they worked.

[Mike_117]

I took my 4in1 completely out of the case and just strapped it down with a zip tie. No worries about making cooling holes. When I put on the carbon tail, it allows more air into the front canopy so I didn't have to add any new vents. Seems like a better fix. I just let it sit for few minutes between flights, the motors have the most heat buildup on my bird now.. ...

- I'm not sure nose weight is the best option. The cx has its FF limitations and everything I have tried, ...weight, shortened flybar, #2,3 servo positions.. etc.. just throws off the control and CG of the heli..

[jermo]

I'd think adding weight to be a bad idea..

What might be a viable option is to modify the battery tray to allow the battery position to be more adjustable (and the ability to prevent it from shifting during use). This would allow us to move the CG without adding weight.
Jermo

[Mike_117]

jermo,
An option for that is,
just cut the velcro stop.
Take a ziplock disposable container and cut to the dimensions of the battery tray and secure it to by aligning it with the 4 screws.
use another strip of velcro to secure the battery and possibly also use a rubber band and a velcro strip.

I bought the Align velcro straps for the trex battery. That wraps through without the plastic spacer between the gear/battery.

You will have to adjust the lengths of the servo arms to counter the weight and then trim out on the tx. you get faster FF but it likes to swing like a pendulum when you stop... To stablize that I added a more weight to the flybar..

I flew with a short flybar/with extra weight on the #3 servo horn.. very difficult to control.. it flew pretty fast.. spun it 180 and it tilted over and went head first into the ground.. ..

[Balil]

2nd cx2 will be here monday-tuesday, i cant friggin wait cause im puttin a aluminum top and bottom head assembly.