Happy New Year, with a gift, from the new MODERN PRA!

How would you, like a State-of-the-art lightweight electric lithium ion battery powered PRE-ROTATOR AT COST?

PRA has created an ‘OPEN SOURCE’ Project to create one for all of us. See the project here: http://www.pra.org/forums/showthread.ph ... escription

We are looking for a few good women and men to make this happen for all of us as we all need lightweight pre-rotator/pre-spinner.
The following are the job descriptions for those who would like to make the world a better place for those with our same passion.

If you have these skills sets we NEED YOU:

1) Internet Researchers
2) Electronic Technicians
3) 'MPU' Programmers - Micro Processor Unit - programmers (1)
4) Machinists (Auto Cad type programmers) too
6) Flight test-pilots
7) Technical Writers (1)


Note: (x) = current number of staffed positions However we wish many in each group we cannot have too many volunteers.
At the completions some of these positions will become paid job at reduces rates as we pass the COST on to our members for built components or entire units.

John being that this prerotater discussion has been going on for a week or 2 I have
had time to give it some thought.
I understand the concept that prespinning to less RPM works just as well.
Also the idea of keeping a low torque prerotater running through the take off roll
is brilliant and has been proven.
Here is where I beg to differ. The brushless DC motor with the odd voltage and
l-ion battery pack seems like a unneeded PITA.
How about using a regular 12 volt battery that is just a bit larger than normal.
Add to that a inverter that is about $ 50. something like this

http://www.ebay.com/itm/1500W-Watts-300 ... 27e905032e

then throw in a industrial motor drive like this

http://www.automationdirect.com/adc/Sho ... D5-240-10C

Take note that the shipping weight is just 1.4 pounds.
plus it will give you a soft start. Almost constant torque across almost the entire RPM range
plus adjustable acceleration and current limiting.
Also that drive should work nicely with any control scheme that you can come up with.

And a electric drill for a motor. Most drills are light weight, have threaded holes for handles
that would make mounting easy. and have a universal motor that will run on AC or DC.
They also come in a number of RPM ranges. Get rid of the variable speed triger switch and away
you go.

Aside from my examples for a small single place machine you could use a smaller inverter
and motor drive.

Just my 2 cents worth.

Humm

I should have though of that. Doing it the S.D. house now and have done boats for folks all my life.
If I can control it with a rheostat it may work as it's not like it needs to be running very long. And while it off it's recharging.

Will put that on the test list... Good one!

There is no need to use just a rheostat with the motor drive I gave
a link for you can feed it a 0 - 10 volt signal and make it run any
speed you want. Plus it gives you a current limit and adjustable
acceleration. All in a very well proven package.

rheostat is just for a test to make sure at low power it still has as much force as the same motors when you create the sine-wave with a pulse with modular and a look-up table.
Also will test how long it will run under load with a 12 volt battery.

Rheostat is faster than writing test code!

For those working on their own I thought I would pass on our motor, controller, and gear association made up of many companies.

http://www.globalspec.com/

I've joined them and get emails now it an interesting source!

Something I have been wondering about is the electric outboard trolling motors? The entire motor costs less than 200 and comes with a 5 position speed switch/controller and runs off 12 volts? Has anyone tried or thought of these? I was thinking of getting one just for the motor and controller.....

http://www.ebay.com/sch/i.html?_from=R4 ... r&_sacat=0