lml@lancaironline.net Mailing List Archive

John,

I don't know much about Castleberry. I do know they were the supplier for Sporty's electric AI for a while and then I think what happened is they decided they wanted to own the marketing themselves. The result was a steep price increase and effectively lack of a product from Sporty's. No doubt their volumes nose-dived as a result.

I ended up with a mid-continent which has 1-hour standby and appears to be in a similar price range once you count the battery. The mid-continent battery is attached directly to the AI as you propose. http://www.lifesavergyro.com/ Part of my reasoning is that the conspicuous players in any industry have more to lose when they abuse customers.

I love mine and ended up buying one for the cessna also. I even prefer flying behind it vs. the vacuum.

(but I also have vac in the IVP with a wet pump. that's the backup)

Colyn

On Jan 19, 2012, at 9:01 AM, John Hafen wrote:

Check out the attached. It's an electric AI with a battery backup, that, I'm thinking, could be connected directly to the AI - bypassing everything else that may get cooked by lightening or just fail. What are your thoughts about this potential solution?

On Jan 18, 2012, at 3:27 AM, Frederick Moreno wrote:

"I’ve noticed that the term ‘spinning mass gyro’ is being used in this discussion, as opposed to ‘vacuum driven gyro’. Does that mean you all are comfortable with an electrically driven AI? That would make sense if the AI contains only contains a simple electric motor which consists of windings and permanent magnets. Those tend to be very tolerant of voltage spikes."

Yup. But.....

"But if the electric AI contains even a single electronic component (voltage regulator, integrated circuit, etc), wouldn’t that make it vulnerable to the same lightning strike that took out my fancy EFIS, charging system, isolating diode, and backup battery?"

Aye, and there's the rub with an all electric airplane. (I own one.)

Life is full of choices which means you have to make a series of hopefully thoughtful decisions.

One could choose a vacuum pump and gyro, but history shows that vacuum pumps fail frequently, much more frequently than airplanes getting struck with lightning. So I voted to dump the vacuum pump and use an electric AI, and then follow the guidelines of current certified all electric aircraft - dual alternators, dual batteries, alternate feed pathways for power, Schottky diode pathways, and I added huge transient suppressors (see Perehelion design).

I could not include the lightning protection put in certified aircraft. So I put big ground lines in to all extremities of the aircraft in an attempt to route any passing lighting bolt around the hot side of the electrical system. Nonetheless, there is no question I could get nailed by lightning taking out all the electrical systems. The defense if obvious: if the Stormscope says there is a thunderbumper in the neighborhood, the decision is to leave the neighborhood. That is probably the most important decision of all.

I do have a vertical card compass front and center. If the lightning leaves that alone, in theory I could use it to keep it pointed in the right direction while I fly the back up steam gages for altitude and airspeed. I have done so flying VFR while my Cheltons were inoperative due to some GADAHRS work.

You pays your money and you takes your choices. You can reduce the risk, but it will never be zero. Thoughtful decisions are very important in the risk reduction process.

Fred