# Turbinator annual inspection

#### bryancobb

##### Junior Member
What kind of 12V battery did you find that weighed a pound?
Most lawn-mower size ones I've seen weigh 10 or so.

#### StanFoster

##### Active Member
Bryan- excuse me for feeling like I am sitting in court with you cross examining me. I am not making this stuff up just to be blabbing here! Its a real small lithium ion battery about the size of a cigarette pack. from a golf cart shop. Heres the kicker, my main Odyssey 680 batteries weigh 30 pounds together and are back behind my turbine. I could replace them with lithium ion batteries that together weigh 7.5 pounds. That would be around a 22.5 pound savings..........but I need the weight of those heavy batteries for my weight and balance. I would have to have those super light batteries clear back on the tail and with more ballast also. My 30 pounds of batteries are on a moment arm of 48 inches. Their weght is aproximately 1/30 of my flying weight of 900 pounds. The batteries can slide for and aft on my tail boom. Since they are 1/30th of my average weight, every inch I move them forward causes my CG to shift 1/30th of an inch as well. But lets drop those 30 pound batteries and replace them with the 7.5 pound total that the lithium ion batteries weigh. The 30 pounds of batteries are on a 4 foot moment arm. The 7.5 pound batteries are 1/4th the weight and would need to have a moment arm 4 times farther back - or 16 feet back. I am not near my calculator, but it would be slightly less than 12 feet since my total flying weight is 22.5 pounds less. Stan

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#### bryancobb

##### Junior Member
Oh OK...One Odyssey is 15#. I was thinking those were the ones you were saying weigh 1#. I Understand now.

#### bryancobb

##### Junior Member
If you could lose 22 pounds of gross weight, I would bet the decreased lift you would need, could be used as thrust instead, and you could get a couple more knots out of it before the belt-slip point is reached.??

#### StanFoster

##### Active Member
Bryan- It is "possible" for me to get down to 180....but very unlikely! But, lets say I did...thats the only way I could get rid of those heavy batteries without adding ballast on the tail......then I could switch to those super lightweight lithium batteries, saving 22.5 pounds plus 40 pounds of myself...for over 62 pounds less gross. Even though it flies like a wild cat now...it would fly like a scalded cat then!

But...reality.....I can get down to 205 when I want to.........

Stan

#### baronpilot

##### Newbie
Stan,

What do you reccommend I do? I am 185 and my machine is tail heavy with the batteries about as far forward as I can go. I have 22 lbs of ballast on the floor boards to make it level.

It seems silly to carry that much weight for no reason other than to balance the ship. Has ony one built a led weight that fills the front of the right skid or something like that? I could probably get away with 5 lbs up there instead of 22 on the floor.

#### Lee Scatt

##### Crash-test pilot
Change the batteries like Stan just described.

#### baronpilot

##### Newbie
Change the batteries like Stan just described.

I knew you were going to say that

I just bought the batteries, but I think you are right. There is no sense carry around the extra weight. I think the LI-ion batteries are pretty expensive though.

#### StanFoster

##### Active Member
Todd- Exactly as Lee said. I would go to those lithium batteries......a dual pair almost has as much cranking powered as two Odyssey 680 batteries....but weigh 22.5 pounds less.

Your weight and balance would be solved....your lighter weight.....those lighter batteries...and if you had landing gear fairings and a swashplate fairing....you would have the fastest Helicycle out there.

Stan

#### bryancobb

##### Junior Member
On a \$45k to \$50k ship...I'd spend \$500 in a heartbeat to drop 23# of batteries and and 22# of weight in the floor and fix the tail-heavy condition!!!!

In 100 hours of flying, that would pay for itself in fuel savings alone!'

#### ylf

##### Member
I knew you were going to say that

I just bought the batteries, but I think you are right. There is no sense carry around the extra weight. I think the LI-ion batteries are pretty expensive though.

Todd,

I bet you could sell your current batteries on the builder's group and get most of your money back.

Mike

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