Brushless Reverser

[AeroJDK]

Alright...been trying to find a solution to this one and nothing seems to jump out, so I thought I'd throw it out on the forums. I'm trying to reverse a brushless motor (Plettenberg 220/30) in flight since I'm actually using it as a control fan. I realize that I won't get full thrust in the reverse direction, but nonetheless, I'd like to get some thrust in the reverse direction.

I've been in contact with Castle Creations (I'm using the Phoenix HV-45) and they simply say "No...you can't do it." I'm thinking that since it comes down to switching two wires, I just need to find a way to switch them remotely. Any thoughts or suggestions? The motor will be pulling 40 Amps at 30 Volts, so whatever relay or method is used, it need to be able to support that. I'm open to ALL suggestions...thanks in advance!

Jon

[AndyOne]

Jon,

Look-up brushless controllers for cars, some of them have a reversing function built-in.

Andy.

[AeroJDK]

Is there a car brushless speed controller that can support that can of power (30V, 40A)? I have been looking at DIY solutions that would go inbetween the ESC and the motor, but if there is a motor speed controller that can support an 8S2P Li-Po pack, that'd be perfect. Anyone know of any?

Jon

[Kwok_Yu]

http://www.rcgroups.com/forums/showthread.php?t=361335
This thread may interest you. I remembered it and looked it up for you. The person wanted to use a switch to reverse the brushless motor, but ended up frying the esc.

-Kwok

[alexcmag]

You will need a Castle Creations Mamba BL ESC.

It is too expensive, if you think the circuit is exactly the same and the firmware is almost the same from an airplane BL ESC, but works well...

[TMetalMan]

The Mamba is only rated for 4s Lipo. It is only rated at 25amps cont., and 50amps surge. I come from the RC car region, and to my knowledge, there aren't many that can switch like that. BUT, there is one controller that I know of - the BK Electronics Warrior controllers. These have a jumper for programming that can be used to switch the rotation of the motor. Off the top of my head I don't know how it works, but I think that you just unplug the jumper while the controller is on, it will beep, and then you replace the jumper. These controllers come in several amp/volt ratings. By looking at them though, you would be spending at least $400. Their airplane controllers are also too expensive. As far as I know, there are no other car controllers that can support that voltage that would be reversible in-flight.

[Discharger]

Check out Kontronic Jazz ESC, I think it may have a reverser for car use. Saw some mention of this in the instructions but did not interest me at the time as I was setting up constant speed heli mode.

[Discharger]

A possible DIY solution could be to use 4 power fets in an H configuration in two motor wires. Some bench fiddling required and possibility of unintentional smoke and flames.

[AeroJDK]

This info is great...but it just hit me: could any of these other ESCs be used with Li-Po cells? Currently, we're using the Phoenix HV for that specific reason, but as mentioned above, this controller doesn't have reverse capabilities. Would any of these others be able to use a Li-Po power source?

Jon

[Discharger]

Yes, check out the Kontronic site.

[CrashingDutchman]

I can't recall where I saw a movie about this... could be here on rcgroups, just don't remember...

In this movie, someone was flying a shockflyer. Instead of changing direction of motor, he somehow changed the prop in flight and made the plane fly backwards

Amazing video to see!

CD

[Ron van Sommeren]

A possible DIY solution could be to use 4 power fets in an H configuration in two motor wires. Some bench fiddling required and possibility of unintentional smoke and flames.Brushless controllers already have (at least) 6 fet's in an H-bridge.
It should not be to difficult to implement the 'reverse' function in the controllers software, no more than a few lines of extra code I guess. Of course the controller has to make sure that the motor is (almost) at standstill before reversing.

[AeroJDK]

Again, thanks to all for their help on this topic. From looking around, it seems the Hacker Master 77-O-Navy will do the trick. I'm going to be using 8 LiPo cells and it supports up to 10, PLUS it supports reverse mode. I'm guessing that since it does, this controller waits for the motor to spin down first and then switches, but I haven't been able to verify this as of yet. Does this selection seem right to anoyone else? With it's expense, I would rather not go and order on of these and be wrong :-)

Jon

[Andy W]

I have a few cars. Some have modes to protect them, but in general, they don't always seem to wait before slamming into reverse.. :) Gear trains and belts take a pounding, but with rubber tires, it sounds cool! :)
..a

[Peter Seddon]

I don't see why you need to wait for the motor to stop. As long as the current is controlled and the inertia (ie stored energy) of the mechanical load is low then I would expect a fairly rapid controlled stop and accceleration in reverse.

Regards Peter

[Miami Mike]

I can't recall where I saw a movie about this... could be here on rcgroups, just don't remember...

In this movie, someone was flying a shockflyer. Instead of changing direction of motor, he somehow changed the prop in flight and made the plane fly backwards

Amazing video to see!

CDThere are a few planes out there like that and one was even featured in the AMA magazine. It was in the "Electric Issue".

Here's an RCGroups.com post about a German video:

http://www.rcgroups.com/forums/showthread.php?t=366196

Here's the link to the video, but it doesn't work:

http://modellvideos.de/videos/KnuffelVerstellprop-die-zwote.wmv

Google gets lots of hits for it though, so it's still out there:

http://www.google.com/search?hl=en&q=%22KnuffelVerstellprop-die-zwote.wmv%22&btnG=Google+Search

And here's another thread with links to that and similar videos:

http://www.rcgroups.com/forums/showthread.php?t=363123

[corndog]

Theres usually an ad from hobby lobby on the ezone home page about that thing. Not there today of course, but heres that video-

http://www.hobby-lobby.com/variablepitch.htm

[Bill Mixon]

I'm trying to reverse a brushless motor (Plettenberg 220/30) in flight since I'm actually using it as a control fan. I realize that I won't get full thrust in the reverse direction, but nonetheless, I'd like to get some thrust in the reverse direction.
Jon,
What kind of control fan will this be, what is the application?
It would be helpful to know exactly what you are trying to do.

I contacted some of the esc makers about building a esc like this or a switcher that would connect to the wires from the esc. No one was interested. I wanted it to experiment with reverse thrust on small models before flying with variable pitch systems.
With nothing available I simply setup a mechanical DPDT switch with a aux. servo to change direction. It works really well however I quickly learned that the motor could not be turning when switching rotation. I use the esc with the brake on and watch for the prop to stop before powering back up.
So when I'm flying with it I pull the power all the way off, then flip my gear switch to change rotation, then look at the prop to see that it is stopped, then apply power with the motor turning in the other direction.
With the motors and esc's I tried it was not possible to change the direction while the motor was still turning even with no throttle applied. It was a must to have the motor stopped or turning very very slowly.

[Miami Mike]

If I was going to try that I'd use a small DPDT relay instead. The PC board from a broken servo could be adapted to energize it. Connect the relay coil through a series diode to the terminals where the servo motor used to be, and either fix the potentiometer at the halfway point or build an equivalent resistor divider.

To save power, wire it to your brushless motor so that you get reverse thrust with the relay energized.

[Franck]

IVe used a similair device to reverse thrust on one of my foamy plancks. Used a switch and servo in combination with a 2207 ACW motor and 25 amps CC ESC.(with brake on)

Very funny aerobatics possible with this setup !
\
BEst regards,

FRanck

[Alexander Cui]

Why do not you use a EVP mechanism like this:http://www.5irc.com/content.asp?id=612206

[Alexander Cui]

Why do not you use a EVP mechanism like this:http://www.5irc.com/content.asp?id=612206

[Miami Mike]

That appears to be equivalent to the Hobby-Lobby unit that corndog mentioned (http://www.hobby-lobby.com/variablepitch.htm).

http://www.hobby-lobby.com/images/evp201.jpghttp://www.hobby-lobby.com/images/evp201b.jpg