[KRviator]

G'day all...

I have a PlanePower FS-14B as my primary alternator, and am running dual P-mags with which I am very happy, with a Rotec TBI delivering the fuel.

But, in the quest for a more efficient plane, am giving serious consideration to running an EFII system. That will require a backup power supply of some sort, and that got me thinking.

Both PlanePower and B&C obviously have alternators that can mount on the vacuum pad, and, with a proper adapter, you can mount them on the hydraulic drive as well. Unfortunately, I don't think I have the accessory gears going to the hydraulic drive, so without removing the accessory case, that probably isn't an option for me.

Does anyone know of a supplier that will let you mount an alternator in a disused magneto drive, or has anyone done something similar themselves?

 

[rzbill]

Rob,
I have not seen that option offered by anyone yet but I guess it could be out there somewhere.

Please be aware that RPM is a crucial factor in getting power from an alternator. For example, the B&C 20 amp vac pad alternator uses the same windings as their 40 amp belt driven unit. Difference in power output is RPM since the belt unit spins much faster than the vac pad.

The mag RPM is less than half the vac pad RPM so power output may be quite small. Sucess depends on your expectations. Standard Mags and P-mags generate power from mag RPM so it is certainly possible to get some generation using mag RPM levels.

Linear scaling by RPM says a vac pad alternator output would be cut down to approx 1/3 of its rated output at mag RPM.

Hope this helps your thinking.

 

[johnbright]

gears in behind the accessory case

Hi KRviator,

I think if you're driving the cam and mags you have all the gears possible in the accessory case.

Brian Meyette's BUILDING THE SUPERIOR SL-360 (text & pics)

 

[KRviator]

G'day John,

I'm not sure either way at the moment... The Lycoming overhaul manual suggests several more gears that aren't shown in your top photo - the bottom one doesn't appear for some reason.

I'm going to have a chinwag with a mate who has a milling machine and see if it is possible to build a blanking plate for the mag housing that will be able to hold an AND2000 drive. The big question will be are any alternators available with a drive shaft long enough to be installed and have their teeth mesh with the accessory case gears.

 

[johnbright]

Hi KRviator,

I'll see if I can fix the bottom photo. It's the inside of an accessory case.

Perhaps the gears in the manual are in the drive adapters for the vacuum pump and propeller controller.

Below is a propeller controller drive adapter.

 

[madhun]

G'day John,

I'm not sure either way at the moment... The Lycoming overhaul manual suggests several more gears that aren't shown in your top photo - the bottom one doesn't appear for some reason.

I'm going to have a chinwag with a mate who has a milling machine and see if it is possible to build a blanking plate for the mag housing that will be able to hold an AND2000 drive. The big question will be are any alternators available with a drive shaft long enough to be installed and have their teeth mesh with the accessory case gears.

How did you get on here KRviator?

I've been giving thought to the same issue recently.

A competent machinist, especially one with access to a cnc milling machine , could no doubt fabricate a plate that mounted the alternator to the mag attach points with a female spline attached to a re-manufactured magneto drive shaft.

An alternative might be a gear arrangement similar to a Bendix drive on a starter motor. The carrier assembly not a significant engineering feat.

The maths required to gear the assembly wouldn't be rocket surgery either. I'd suggest it not a difficult task for an engineering shop specialising in gearbox modification.

Regards,

Quentin

 

[KRviator]

How did you get on here KRviator?

I've been giving thought to the same issue recently.

A competent machinist, especially one with access to a cnc milling machine , could no doubt fabricate a plate that mounted the alternator to the mag attach points with a female spline attached to a re-manufactured magneto drive shaft.

An alternative might be a gear arrangement similar to a Bendix drive on a starter motor. The carrier assembly not a significant engineering feat.

The maths required to gear the assembly wouldn't be rocket surgery either. I'd suggest it not a difficult task for an engineering shop specialising in gearbox modification.

Regards,

Quentin

G'day mate,

TBH, I haven't pursued it much as I got cleaned up by a kid on a motorbike at the end of Feb and have been grounded since with a busted arm & leg. 34 years to break a bone and I did 4 in one instant, little *******!

I got to thinking that while it could certainly be possible, it would be simpler and probably cheaper to install a standard Vans alternator kit, and replace the FS-14B (with its' voltage set at 14.4) with an original FS-14 (13.8v setpoint) and simply install a pair of blanks over the mag covers. That would give a proven fail-safe setup, and eliminate the possibility, however remote, that a slight misalignment or grinding of gears would send metal through the engine.