External alternator

I have an external alternator with an Airmaster propellor on my Edge Performance 912 STI.

I have the small brush assembly mounted on the back of the gearbox. I have over a thousand hours with no problems. It’s possible that will be your option 

Ed

Why do you need another alternator ? There are already two and a battery backup which gives you triple redundancy ??  Going to quadruple seems a little excessive ?

Ed Midgley wrote:

I have an external alternator with an Airmaster propellor on my Edge Performance 912 STI.

I have the small brush assembly mounted on the back of the gearbox. I have over a thousand hours with no problems. It’s possible that will be your option 

Ed

That is interesting.  I inquired of Airmaster about the small brush assembly and got crickets in response to several emails.  I then asked RANS since I bought the engine and prop through them.  They inquired and also had a hard time getting a response, but finally got a response that this wasn’t available for the 915.  No reason given as to why.  So, I ruled out that option.

Do you know a direct contact at Airmaster that might respond to another inquiry?

Glenn Martin wrote:

Why do you need another alternator ? There are already two and a battery backup which gives you triple redundancy ??  Going to quadruple seems a little excessive ?

You really only have one.  A is dedicated to running the engine so only B is available for ship power.  B puts out 28 amps at cruise.  I am building a fairly well equipped IFR airplane.  The heated pitot alone can draw 10 amps, at least initially.  Landing lights are 6 amps.  Strobes, nav and beacon are another 4-6.  It all adds up.  My steady state load at night in cold weather can easily exceed 20 amps and I would like a little more headroom.  And, for IFR flying, I like the redundancy. We have dual ECUs, dual spark plugs and dual injectors for a reason.  I similarly like dual alternators for ship’s power.