[ARC5] Radios in XB-19?

Mon Jan 11 16:34:16 EST 2016

That's an interesting question and I didn't know what the answer was.  So I
went to the Wiki:

 Given the right auxiliary and control equipment, an M-G set or rotary
converter can be "run backwards", converting DC to AC. Hence an inverter is
an inverted converter.[11]
<https://en.wikipedia.org/wiki/Power_inverter#cite_note-11>

   1.  Owen, Edward L. (January–February 1996). "Origins of the
Inverter". *IEEE
   Industry Applications Magazine: History Department* (IEEE) *2* (1):
   64–66.

I like the Wiki so much, at least for technical questions, that I send
them money every year.

73

de Bart, K6VK ##

-- --
Bart Lee,
Attorney at Law
Office Phone 415 956 5959 x203
Office Fax Line 415 362 1431
Cell Phone 415 902 7168
Snail Mail: 388 Market St #900
San Francisco, CA 94111-5311
www.bartlee.com
<http://www.LawForHams.com>

On Mon, Jan 11, 2016 at 12:46 PM, Jay Coward via ARC5 <arc5 at mailman.qth.net>
wrote:

> You are inverting the DC back and forth?
> Jay
>
>
> -----Original Message-----
> From: Tim <timsamm at gmail.com>
> To: Michael Hanz <aaf-radio-1 at aafradio.org>
> Cc: To: ARC-5 <arc5 at mailman.qth.net>; Military Surplus Mail List (
> milsurplus at mailman.qth.net) <milsurplus at mailman.qth.net>
> Sent: Mon, Jan 11, 2016 10:57 am
> Subject: Re: [ARC5] Radios in XB-19?
>
> Hi Smart Guys!  Question:  Why are DC-to-AC devices called "inverters" ??
> Seems like an odd choice for a name...What am I missing?
>
> Tim
> N6CC
>
> On Mon, Jan 11, 2016 at 5:47 AM, Michael Hanz <aaf-radio-1 at aafradio.org>
> wrote:
>
>> I think it more likely that Douglas and the Army had studied Navy
>> practice, which included mounting an 800Hz alternator on one engine, and
>> decided to try having both AC *and* DC available as a development
>> platform.  The Navy was pretty much ahead on everything related to
>> avionics, and by the late 1930s had recognized that new devices like radar,
>> HF transmitters like the GO-9 and GP-7, and devices requiring small amounts
>> of AC power, such as navigation equipment and the like, were going to need
>> both kinds of power.  However, in their haste to implement a native AC and
>> DC environment on their combat aircraft, the Navy missed the mark with
>> 800Hz, because the higher frequency needed compensating capacitors
>> installed that could be adjusted for a particular load to eliminate the
>> effect of inductive reactance in the alternator.  As it turned out, 400Hz
>> was a better compromise between eliminating that need and still reducing
>> the size and weight of transformers in airborne equipment.  That's how we
>> ended up with the current standard for aircraft.
>>
>> That being said, the Army was slow to follow the Navy's lead, preferring
>> to keep the primary mode of power to DC, and distributing small DC to AC
>> inverters to where they were needed in a point of presence approach.
>> That's how they accommodated new pieces of equipment in all the heavies,
>> including the B-29.  A DC bus was never far away throughout the airframe,
>> and tapping into it was easier and weighed less than trying to run two
>> separate busses throughout the plane during manufacture.  You can see a
>> couple of these (by 1945) ubiquitous MG-149 alternators at the navigator's
>> station in the Enola Gay -
>> http://aafradio.org/NASM/Enola_cockpit_026a.jpg - though larger
>> alternators were required by power hogs like the APQ-13 radar.
>>
>> The Navy did the same thing (to an extent) with their 800-1 alternator (
>> http://aafradio.org/docs/800-1.htm ), (again, fighting the inevitable
>> evolution to 400Hz), but those appear to have been used for the same reason
>> that the Army did - to serve unexpected pieces of equipment being
>> retrofitted to aircraft after they came off the assembly lines.  It wasn't
>> until after the war when technology settled down enough to think about
>> providing both kinds of power throughout any given airframe.
>>
>> 73,
>> Mike  KC4TOS
>>
>> On 1/10/2016 11:23 PM, Bart Lee wrote:
>>
>> I heard that 400 cycle power was implemented in the B-29 because
>> otherwise the weight of the transformers would have been too much to fly
>> well.  (Incidentally, my father was a B-29 Flight Engineer).  Maybe the
>> XB-19 prototyped 400 cycle AC power.
>>
>> 73 de Bart, K6VK
>>
>> On Sun, Jan 10, 2016 at 4:44 PM, Jay Coward via ARC5 <
>> arc5 at mailman.qth.net> wrote:
>>
>>> Well Jack and the Group,
>>>  I've always wondered what radio equipment was in the Bolo.
>>>  As far as AC in the XB-19 , it may have been the power distribution
>>> system and the AC to DC was done locally at the equipment. Just guessing as
>>> there is not much AC gear surfacing from that era.
>>> Jay KE6PPF
>>>
>>>
>>> -----Original Message-----
>>> From: Jack Antonio <scr287 at att.net>
>>> To: milsurplus <milsurplus at mailman.qth.net>; ARC-5 List <
>>> arc5 at mailman.qth.net>
>>> Sent: Sun, Jan 10, 2016 9:59 am
>>> Subject: [ARC5] Radios in XB-19?
>>>
>>> Does anyone have any documentation on the radios installed
>>> in the Douglas XB-19?
>>>
>>> Note, this not a typo, I am not referring to the B-18 Bolo.
>>>
>>> The XB-19 was the large experimental bomber that was used more
>>> as a test bed for large aircraft systems, rather than a serious
>>> contender for production.
>>>
>>> What drives the question, is that one of the features of the plane
>>> was the use of an AC power system.
>>>
>>> So I'm wondering if the Army used AC powered radios in the plane.
>>>
>>
>>
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