>>> Combustion pressure was believed to be a major design issue.  Subsequent
>>> design modifications and dyno and flight testing helped somewhat  but
>>> ultimately we concluded that even in improved, modified form,   housings of
>>> aluminum alloy using materials available at that time was not  the best
>>> material for long term service life.   Our experience with the  Mazda factory
>>> cast iron housings was very good in all respects except weight.   It seemed
>>> that the rigid cast iron housings, together with the steel  insert in the
>>> throchoids, provided a very solid structure with none of the  problems
>>> involved with aluminum.  But due to the weight of the cast iron,  to attain
>>> the best compromise of power-to-weight and longevity, it was   determined
>>> thin-wall steel housings with nitrided wear surface would be  best.  We
>>> researched investment casting of these and found it was simply  was too
>>> costly.  That is when we turned to furnace brazing.
>>>
>>> For doing the first set of these housings test housings, design  methodology
>>> was very basic.  But Everett spent considerable time researching  and
>>> computing stress-deflection (compression) of  columns from  combustion
>>> pressure and  a stress analysis (elastic strain) of stress in  the end
>>> housing wall produced by combustion pressure of 1,000 psi.   Deflection rates
>>> were calculated for a 1" square plate fixed on all edges and a   uniform load
>>> over a small circular area at the center for steel .120 thick,  equivalent
>>> cast iron .200 thick and aluminum .200.
>>>
>>> After the prototype housings were furnace brazed they were  machined  and
>>> surface lapped, then shipped for nitriding.  After nitriding we  finished and
>>> final lapped prior to assembly.
>>>
>>> Weight of furnace brazed steel housings taken during assembly of  the power
>>> section were:
>>> Center housing--9.75 lb
>>> End housings--10 lb each
>>>
>>> By comparison, our cast aluminum housing weights--
>>> Center housing--8.75 lb
>>> End housings 7.5 lb.
>>>
>>> Steve Beckham.
>>
>>
>>
>> Thanks, Steve,  for the extremely interesting account.  All of this
>> information would be lost without your publication of it and it  points
>> the way for us to go onward.  In particular it is amazing that
>> aluminum housings only  save 5 lbs total for the single. Thin steel
>> brazed inserts is the practical way to go as you have pointed  out.   I
>> wonder if some of the machinists on this list could produce them.
>> All we need is two housings and an eccentric for the single  cylinder
>> to be a viable reality.  That would be a nice package to find at  the
>> door.     Jerry
>>
>
> Yes Steve, great work !! Thank you !
>
> We should realize the aluminum housings save about 25 pounds over  the
> stock cast iron housing on a single rotor. So, these brazed steel  at 20
> pounds less than stock as so close :-)
>
> http://www.racingbeat.com/FRmazda2.htm
>
> One thing not clear to me, these brazed steel housings - they are  simply
> thinner versions of the cast stock, or is there an aluminum part  as well
> forming a sandwich end housing of a thin steel layer next to the
> combustion chamber, and an aluminum section adding strength like the
> foam in a Rutan plane ? If is it only a thinner steel end plate, the
> e-shaft would need to be custom made shorter ?
>
> -dave

Guys--regarding your additional questions about construction and  design of
our furnace brazed prototype end and intermediate housings,  these  rotary
engine housings were not in any way copies of a standard Mazda cast  iron
housing.  But they were designed specifically to accept a standard  Mazda
rotor housings with peripheral ports.  The end and intermediate  housings
contained no aluminum or cast iron...they were all steel except for  flux and
paste.  Doug Johnson of Precision Castparts (now retired and  building a
Bonneville streamliner) was our technical advisor during the  evaluation and
sourcing process for both investment casting review and finally the  furnace
brazing approach adopted.  The flat pieces were all lazer cut by BBC  Steel
in Canby, Oregon and round columns machined prior to fixturing and  furnace
brazing.  Each housing looked outwardly similar in appearance to our  last
generation SuperLight aluminum housings and  the end housings were  designed
to accept the one of a kind engine mount used in the RV-3,  Engine  mount
ears were cast into the side of each housing. Photos of this mount/ housing
configuration were distributed earlier showing this engine mount  with the
all-aluminum engine installed in the RV-3.  Hope to be able to  provide you
further clarification.
Steve Beckham.

Brazed steel engine blocks are not new. Mercedes used them right  after WW II
in their racing cars. Crosley used the idea in its four cylinder  engine
for its little sports car back in the late 40's and early 50's.
I had a Crosley sedan while I was in college.

It was also used for a short while in early Mooney Mite's. Scaled  down P51s
so to speak.

http://auto.howstuffworks.com/1949-1952-crosley-hotshot-and-super-sports1.htm

"The cast-iron Hotshot/Super Sports engine, called CIBA (for Cast  Iron Block Assembly)
was the successor to an earlier Crosley powerplant that was uniquely  made up of
stamped steel sheets. This earlier engine, dubbed the Crosley Cobra
("Cobra" for COpper BRAzed), used 125 thin steel stampings brazed  together
in a 2,060°F furnace. With its nondetachable head, the Cobra block  assembly
formed a single, lightweight, layered unit."

"The Cobra engine's cylinder sleeves were iron and the crankshaft rode
in five beefy main bearings. This engine, like its cast-iron CIBA  heir,
boasted a shaft-driven overhead camshaft and full-pressure  lubrication.
Bore and stroke being over-square helped keep down friction and wear."

"The Crosley Cobra block and integral head tipped the scale at all  of 14 pounds.
Fully assembled, the engine weighed only 138 pounds. Conceived for  the military,
the Cobra four was designed to run at a constant rpm. In cars, the  varying rev
range caused valve-seat inserts to crack, and the block tended to  warp if the
coolant fell below a certain level. Also, electrolytic action  between the steel
and copper layers could cause leaks."

It was also used for a short while in early Mooney Mite's. Scaled  down P51s
so to speak. When I was 14 and learning to fly the Mooney Mite was  hot stuff.

http://www.mooneymite.com/articles-history/Avweekaugust1948.htm

"Its primary advantage is its economy of operation, due to the use  of a 25-hp.
Crosley Cobra engine, adapted from the Crosley automobile. Plane  will be
priced at around $1600, the lowest priced airplane on today's market."

The idea goes even further back than that as the OX5 had welded or  brazed
water jackets as I recall.


Paul Lamar ...No rotor no motor.

Circle track racers in the 40s with the Ford V8/ 60 had welded sheet
water jackets to reduce weight. The water pump fed the coolant  straight
into the jacket between middle two cylinders rather than into the  front
of the block behind the water pumps.
Nuthin new under the sun...
Dave McCandless

Absolutely.  Nothing new at all with furnace-brazing of various  metals for a
panoply of general consumer to aircraft products... from heat  exchangers, to
engines to propellers.  Allows complex, lightweight structures.   Somewhere
in my file is a reference on the hollow furnace brazed steel  Aeroproducts
propeller designed for the P-51H Mustang.  One of the Aeroproducts  furnace
brazed propellers used also on Reno racer Dreadnought.

Steve Beckham

What you have to watch out for is the dissimilar metal electrolysis  causing
leaks. Plumbing leaks in liquid cooled aircraft are serious. We have  had two crashes
so far caused by plumbing leaks.

Paul Lamar

Steve,  I don't suppose you have drawings and specifications that  you could share?  Or,  Paul,  could you develop a set a drawings?  The area I live in has a very large number of machine shops that are  being killed by the depressed auto industry.  They are hungry for  work.   I could shop the job around and report back.   Jerry

I think I would tig weld it. I don't have time to draw one up as I am leaving
for Chicago tomorrow. Some of the tricky parts are the oil feed to the
e-shaft and the drain backs.

I'll be gone for a week at Barrabo and OSH.
While I am gone the news letter will be shut down. If you just want
to get in touch with just me put Private in the Subject box and I can handle
it on my Linux running on my cell phone :) Don't expect any pictures in return
as they will all be here in CA.

Also I may stop in at Bill Schertz's and see his Kis Cruiser if he will let me.