12v gauges

[Django]

I have been told that either a TBM or TBD(?) had 12v gauges. Is this true? If not, were there any WWII aircraft that DID have 12v gauges? I thought they were all 24v.

[Bill Greenwood]

Almost all Spitfires were built as 12 volt. Some rebuilds have been Americanized to 24 on the theory that more must be better and we must be smarter now than RJM was back then. Mine is as original starts just fine off of a small gel cell battery like a motoriwed wheechair, if the ignition and prime are right. It is easy to overprime when hot. I don't know if the voltage is stepped down to the gauges. I think many guages may be vacumn or direct read and not all electric.

[retroaviation]

If I remember correctly, the AT-6A had a 12 volt system. The rest were 24 though. I think some of the other PT type trainers were also 12 volts. I don't know of any big iron that is though.

Gary

[Edward Soye]

I'm not sure how it corresponds to the T-6 line, but the Harvard Mk II and Mk IIBs were all 12 volt systems. When they got to the MkIVs they went to 24v.

Edward

[B25PBYGUY]

The TBM I fly (Fighter Factory) has a 28VDC, 200amp generator. 24v 36amp hr battery. Thats the WWII configuration.

[Eric Friedebach]

The T-6Gs were upgraded to 24v IIRC.

[Django]

Anyone have a US source for Spitfire gauges?

I need the following...

Oil Pressure
Fuel Level
Temp.
Voltmeter

A start button would be helpful too.

[bdk]

If I remember correctly, the AT-6A had a 12 volt system. The rest were 24 though. I think some of the other PT type trainers were also 12 volts. I don't know of any big iron that is though.

Gary

Thru SNJ-4 and thru AT-6C were 12 volts I believe. Harvard 4 is 24 volts. L-5E and G were 24 volts I think while the L-5 and L-5B were 12 volts.

[EDowning]

Interestingly enough, my 1939 NA-64 Yale, the Grandaddy of all your (and mine) T6s has a 24volt system. I thought that all T6s also had 24v systems. As most of you know the 220 Yales produced were built in Englewood and T6s were coming off the same production line about 6 months later. Why would North American have produced 220 airplanes with a 24v system and then gone backwards to 12v for the next several thousand aircraft?

Add this to the long, long list of things I don't know about warbirds.

[Forgotten Field]

Most airframes started out as 12V prior to WWII. When wiring requirements went up due to the number of systems, 24V was a solution because it reduces the requirements for wire diameter by 1/2, saving a LOT of weight in big airframes. Also, 24V was preferred because it was easier to drive dynamotors for old school radios. After WWII NATO standardized 24V for all aircraft systems for the preceding reasons and because you could use any vehicle as an external power supply.

Not all L-5E's were 24V, only some later ones modified for the USN or USMC. Mine is one of the last ones built and deployed and was never 24V. All the L-5G's were 24V, and some of them were made from E airframes.

[EDowning]

Forgotten Field wrote:

Most airframes started out as 12V prior to WWII. When wiring requirements went up due to the number of systems, 24V was a solution because it reduces the requirements for wire diameter by 1/2, saving a LOT of weight in big airframes. Also, 24V was preferred because it was easier to drive dynamotors for old school radios. After WWII NATO standardized 24V for all aircraft systems for the preceding reasons and because you could use any vehicle as an external power supply.

But why would they make 220 airplanes with 24v and then go backward to 12v on T6s?

[B25PBYGUY]

Hmmm... the T-6's/SNJ/Harvards I have flown had 24V systems. 28VDC generators (50 amp - on line at 1250 RPM, offline below 1000, full rated above 1650 RPM). 24V battery.

[Tim Savage]

Forgotten Field wrote:

Most airframes started out as 12V prior to WWII. When wiring requirements went up due to the number of systems, 24V was a solution because it reduces the requirements for wire diameter by 1/2, saving a LOT of weight in big airframes. Also, 24V was preferred because it was easier to drive dynamotors for old school radios. After WWII NATO standardized 24V for all aircraft systems for the preceding reasons and because you could use any vehicle as an external power supply.

But why would they make 220 airplanes with 24v and then go backward to 12v on T6s?

Eric-

I wonder if Crevasse converted your Yale to 24 volt when he restored it? I am with you, I have a hard time imagining that they built the Yale 24 volt and then reverted to 12 volt for the AT-6C/SNJ-4 line and prior. Many of the earlier airplanes were later converted to 24 volt. We do not see very many 12 volt airplanes come through our shop. In fact of the 20 or so T-6s we annualed last year, I can only think of one that was 12 volt. All the T-6s that I have flown are also 24 volt.

We discovered yesterday while hanging the three QECs on the three airplanes that we are rebuilding that there are some minor changes required to get everything to fit between the 12 volt and 24 volt systems. We had some 12 volt bracketry slip into our workflow and we had to change them so that each component would fit.

[Django]

Anyone have any contact info for Wayne Jordan, Binghamton, NY. I hear he has alot of instruments. Can't find a phone number though.

[Edward Soye]

Of the 5 Harvards I've flown all the Mk IIs were 12v, and all the Mk IVs were 24.

On the topic of the Yale, most of them in RCAF service were eventually relegated to use as Wireless trainers as more Harvards came online. So Eric, is it possible the Yales were 12 V when they came off the line and then with the higher demands places on the electrical system as wireless trainers they were upgraded to 24 volts? There was supposedly a fair bit of conversion done in Canada to the Yales that were bound for France but ended up diverted here. It wouldn't surprise me if this was one of them.

CHAA has just about finished a Yale restoration and it should fly in the spring. I'll have to inquire as to what kind of electrical system it has.

BTW - Eric, did your Yale come out of the Ernie Simmons' collection or did it survive elsewhere?