[burgundyja]

has anyone used a SD20 Alternator 20 amp as there only alternator? i am going to have very little draw and want to keep the weight down.

 

[sjhurlbut]

go for it

Yes people have done it. My airplane is full IFR and with pitot heat on and all light on (HID landing light, stobes, nav lights) and autopilot engaged I pull a max of 22 amps. I have a 60amp B&C. If you're basic VFR with no EFIS gauges, you should be way under 20A. Calculate the draw of it all and I recommend multiply by 2. So if you're under 10A go for it (conservative I know). I have a 6A backup alt and can run everything except pitot heat, 1 radio and some other non-essential stuff with it.

Also realize that with the smaller alternator, the output will drop off more when the aircraft is idling. In other words, idling on the ground with everything turned on may not be enough juice to keep the voltage up. At cruise RPM of course, you'll be fine.

I much prefer the geared alternators because no more alternator belt to change!! Pain in the but to do.

Steve
7A

 

[Ironflight]

I haven't done it, but will seriously consider it when we build the -3....hoping to keep it simple enough to not need many amps, and it sure would be robust!

 

[Vlad]

Alternator

I was seriously considering SD20 then somebody knowledgeable enough (A&P)talked me out of it. Very small output and area of placement is extremely hot -it was his opinion. But, I have the simplest VFR machine, no lights (only position), no strobes, no electronics (I do have good comm). I really like that little gearless alternator.
Is it difficult to install/maintain?

 

[DickDe]

I have a friend who built an RV6 just like Vlad described and I am sure he has 300 hours on the airplane. It has a conventional 0-360, carb. induction, Hartzel C/S, with a B&C alternator and I know of no problems to date.

Dick DeCramer
RV6 N500DD
Northfield, MN

 

[tin man]

has anyone used a SD20 Alternator 20 amp as there only alternator? i am going to have very little draw and want to keep the weight down.

6 inches deep. Are you sure you will have clearance?

 

[burgundyja]

thanks everyone. it looks like i will have no problem with amps. but i dont know about if i have room i dont have the motor mount yet. does anyone have the sd20 on a io-360 200hp 8a?

 

[Vlad]

6 inches deep. Are you sure you will have clearance?

Hmm very tight spot indeed. A little over 7 inches to oil pressure hose and 8 to firewall. Plus magneto and oil filter. Maybe A&P was right. Tin Man could you measure the diameter in the widest of the alternator?

 

[tin man]

Hmm very tight spot indeed. A little over 7 inches to oil pressure hose and 8 to firewall. Plus magneto and oil filter. Maybe A&P was right. Tin Man could you measure the diameter in the widest of the alternator?

Got that info off the website. At one point I thought about putting one on my RV3 but I don't like the idea of a gear driven alternator. Pretty sure Dave Anders has/had one on his RV4.
tm

 

[mburch]

Unless your engine mount is different from mine, I don't think clearance will be a problem... my SD20 has plenty of room:

cheers,
mcb

 

[Vlad]

One more Q Matt

It's clean installation I like it very much. Matt I see you don't have a magneto down under and your filter is angled. Would it be enough clearance down under from Slick? Can you manage couple of pix from the bottom? Do you plan a blast tube?

 

[mburch]

It's clean installation I like it very much. Matt I see you don't have a magneto down under and your filter is angled. Would it be enough clearance down under from Slick?

I don't have a magneto on the right side since I have a single Lightspeed ignition instead. I am putting an impulse-coupled mag on the left side though. If you were using an SD20 with dual mags I assume it would fit, since it's designed to go in the same spot where a vacuum pump would mount.

mcb

 

[Vlad]

Still ?????

I just measured the distance from the extended centerline of vacuum pad to my right magneto and oil filter. It clears the Slick. But it measures only 2 1/8" to oil filter. Alternator dimension from BandC is 4.58 diameter. Looks like I am out of luck there. I have only 4.25 available.