My Onboard Generator Build

[Azalin]

I'm not sure if this is the right place for this thread. Because it is about to power large fuel powered helis I have decided to open it here.

I'll be sharing the build here.

I'm using my homemade generators on my gassers. They are driven by the start shaft because I don't need electric starters as gas engines are pull started. However the gasser that I'm currently building has an OS GT15HZ motor and this motor has no pull start. So I can't run the generator trough the start shaft. It will be driven by the main gear. I know this info doesn't mean much to most of you. Please hold on until I start the build. I'll add photos and give more info.

An onboard generator is simply a system that generates the current for the electronics while the heli is in the air. You still use a small battery (I use 4 cell nimh pack) for the initial start. Once you start the motor your generator starts producing power to feed the receiver (and so the whole electronics) and the battery. This way you never charge your receiver battery. Fly until the jug is empty.

The generator I'm using on my gasser.

750kv Brushless motor as alternator.




3 phase rectifier bridge. It basically converts AC to DC


A voltage regulator. I'm using CC BEC PRO as it allows high voltage because the alternator produces 16-18v at high speed.

[jveneziano]

That's pretty cool, does it take a lot of power from the main motor ?

[Azalin]

Not much really. You wouldn't feel any difference.

[BladeScraper]

Very clever

[Azalin]

Thanks Keith.

M1 16T Raw pinion gear to be used on the generator alternator.

[Azalin]

Currently waiting for the brushless motor.

[Azalin]

Almost finished the motor pinion.



Sent from my GT-I9300 using Tapatalk 2

[J-S-Q]

Great thread. I'm curious to see where you're going to mount the motor/alternator? Guess it would have to be on the side of the heli?

[Azalin]

Thanks.

Yes, I'll mount it to right or left side rear.

I'm hoping to make some progress this weekend.

Still waiting for the brushless motor. Things arrive very late out from China.

[Azalin]

Finished pinion and motor shaft. The set screw is M4.

Sorry I'm going a little slow as I'm working on this project only in my free times.

[Azalin]

Raw aluminum 6061. It'll be machined to be used as alternator mount part #1

[Azalin]

By the way I've decided to use delrin pinion on the brushless motor as it is much lighter than carbon steel. I will cut the new pinion later.

[Azalin]

Checking the pinion on the lathe. There is a small wobble. I need to make a new one. Damn I wish I had a 4 jaw chuck on my lathe.

[Azalin]

The first part of the mount is almost complete but still a lot to do.

The shaft is supported by a bearing

[Azalin]

I spent a lot of time to cut the new pinion right. Made of delrin. 18T.

The brushless motor arrived yesterday. It's time for the second part of the mount.

[meowguy]

I love the idea of this on a gasser where you can literally afford to fly all day and running your on-board battery down is a real possibility. However, at $33.00 per gallon, no one in the right mind is flying a nitro all day long unless you have a factory sponsor buying the fuel.

So I am going to pass on the generator idea for my nitros. But as stated it's a great idea.

[Azalin]

Finished second part of the mount.



Installed.

[ukiah74]

Wow I think thats very cool!! Good job lets see it in flight soon....

[kljw]

This a great idea, well done.
I have just ordered a trex 700n to build in a gasser with a helibug conversion, and this is something that I will be doing at some point.
A few questions if I may.
1 we're did you get all the parts from?
2 please can you provide kart numbers?

Many thanks
Keith

[Azalin]

Hi Keith.

The heli in my first post is a Helibug 700. Same as yours. You can use the same system on yours as well because you don't need the top start as the engine you will use has a pull start. Please follow this link. You will find a lot info there about building a generator. Feel free to ask any questions.