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Old Jan 06, 2007, 02:06 AM
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Kai@UCSB's Avatar
United States, CA, Fremont
Joined Nov 2003
1,987 Posts
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General Electrical Glider Building Question -- Power Switch ?

Hi Guys,

I am now building my first electical glider "Pulsar 2005" and have a simple question. Do you guys use any kind of "power switch" to turn on/off the plane? Since the pulsar doesn't have a traditional canopy which I have to connect the battery and screw the "front-end" pod into the fuslage. I am worry about if there is any glitch, the prop might cut something out

Do you guys use any switch "outside" the fuslage? I guess those switch have to be "heavy" enough to stand the high current.

PS: any picture will be appreciated

Thank you.
-Kai
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Old Jan 06, 2007, 04:06 AM
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Tony Oliver's Avatar
North-East England
Joined Mar 2002
3,401 Posts
In the days when I used conventional 'can' brushed motors I always used a switch in the power lead. It's important to only use it to switch the power on with the throttle set at 'Off'. My thinking on this is that in most cases, you are not switching a high current. The high current only flows at full power so, as long as the contacts in the switch are able to carry the current then arcing and such problems will not exist.

I used 400, 480 up to 600 cheapo motors with 8 cells and had no problems for about 10 years so it must have worked.

The important points : can the contacts carry the load; don't switch the full load - you'll be surprised at the relatively small switches which can work well. Reputable suppliers will be able to tell you the amperage the contacts will carry.

I know the purists will not like this, but I just carried over the knowledge I had with my electric boats. It's rare for boaters not to have switches except in extreme power situations.
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Old Jan 06, 2007, 06:44 AM
flight999
England
Joined Dec 2002
2,344 Posts
Whether you use a switch or not, do not
believe that because the switch is off that
the circuit is safe. Once the battery is hooked
up always treat the equipment as "Live".
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Old Jan 06, 2007, 07:49 AM
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UK
Joined Sep 2002
988 Posts
Quote:
Originally Posted by flight999
Whether you use a switch or not, do not
believe that because the switch is off that
the circuit is safe. Once the battery is hooked
up always treat the equipment as "Live".
Flight 999

I couldn't have put it better myself.

Never work on the model from in front of the nose, if the motor starts up, you on your way to hospital with slashed wrists.
Always work from behind the wing.

Never leave the battery connected, connect it just before you fly, disconnect it immediately after you land.

Brian
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Old Jan 06, 2007, 08:59 AM
turn, turn, turn.
Athol, Massachusetts
Joined Oct 2005
10,382 Posts
My '05 Pulsar, Built by Git-R-Built.com, had no switch. (of course, you can get what you want from dhauch).

I felt I didn't need it. The TP 3s2100 prolite fit just right, so I'd plug it in, put the nosecone on, tape it with 1 round of straping tape with another half round cross orientated from the first, and fly.

Obviously, there was no seperate Rx. battery.
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Old Jan 06, 2007, 09:30 AM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
I don't use switches in general, but I did get a ChPS from Shredair for my AVA - it has a nosecone. The switch is no guarantee the motor will not fire up, it just allows me to keep the Tx off and Rx/servos powered down while I get the model ready to fly.

To prevent accidents, I have a heavy-duty velcro-secured strap that I wrap around the folded blades of all of my high performance models until I'm ready to fly.

..a
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Old Jan 06, 2007, 09:47 AM
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robh's Avatar
Napa, California
Joined Jul 2006
2,604 Posts
Quote:
Originally Posted by Andy W
I don't use switches in general, but I did get a ChPS from Shredair for my AVA - it has a nosecone. The switch is no guarantee the motor will not fire up, it just allows me to keep the Tx off and Rx/servos powered down while I get the model ready to fly.

To prevent accidents, I have a heavy-duty velcro-secured strap that I wrap around the folded blades of all of my high performance models until I'm ready to fly.

..a
I also fly the Pulsar 2005, and do not use a switch. There have been occassions where I thought that it might be nice to have (with the NEU motor and Lipo's it sure does get your attention when running!) but so far it's fine without.

I like Andy's suggestion on the use of heavy-duty velcro... I think that I will do the same, as that should provide a level of confidence that it won't do any damage if it decides to run on its own.

Lastly, I always double check that the throttle switch is off before even thinking about connecting the batteries. It would be my luck...

Rob
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Old Jan 06, 2007, 09:55 AM
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UK
Joined Sep 2002
988 Posts
Quote:
Originally Posted by kkens4
The TP 3s2100 prolite fit just right, so I'd plug it in, put the nosecone on, tape it with 1 round of straping tape with another half round cross orientated from the first, and fly.
I would never tape a nose cone on it just isn't safe to do so.
I always fit at least one 4 mm screw to hold the nose cone onto the fuselage, 2 screws are even better.
If the grass is damp, then tape won't secure the nose cone to the fuselage with any degree of safety.

If possable fit a spring loaded switch to the throttle, that way it fails safe to closed.

Brian
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Old Jan 06, 2007, 11:52 AM
flight999
England
Joined Dec 2002
2,344 Posts
It's not always what you do. It is what
some idiot back in the car park does on your
frequency without checking first!! tight tape
round a cone can lead to expensive blue
smoke emerging from the model too, Switch
or no. I personally don't like switches, they
can give you a false sense of security which
can lead to nasty accidents. (Don't ask me
how I know, I am still trying to forget).
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