WIX Archives
Wow......you guys know your engines !!!! Impressive, tks NT
Posted by Michel Lemieux on Mon Sep 22, 2003 06:54:02 PM
In reply top Re: Pratt vs. Wright Axis vs. Allies posted by Larry Kraus on Sat Sep 20, 2003 05:06:30 PM
: : Longwinded Irony....
: :
: : Kind of an interesting subject, as BMW built the Pratt H
: or
: : net for 10 years as the BMW 132. This was the first "bi
: g
: : nine" for German industry, and based on this engine BMW
: bu
: : ilt the 139. This was a twin 9 built on a common crankc
: as
: : e, a double Hornet as it was. The engine seemed to come
: o
: : ut at the same time as the actual Twin Hornet, the R-218
: 0,
: : a 14 cyl radial, but as a big "18" was unsuccesful. It
: w
: : ould be interesting to know how late Pratt&Whitney worke
: d
: : with BMW as the war began to heat up....This engine powe
: re
: : d prototypes of the FW-190 and Do-217, but had a better
: de
: : velopmental stablemate. The more promising engine that
: re
: : sulted from in house development was the BMW-801 (2562 c
: i)
: : , introduced in production form direct fuel injection an
: d
: : automatic engine control. The BMW 802 continued develop
: me
: : nt from what was learned on the 139, and was 3294 cubic
: in
: : ches, a German R-3350 of sorts. In any case BMW learned
: w
: : ith Pratt, and went on from there. Russian engines were
: W
: : right based, and this was perhaps a better place for the
: m
: : to be long term.
: :
: : The two engines that were the departure points for the c
: om
: : panies in the USA were the Hornet and the Cyclone. Prat
: t
: : went back to smaller cylinders and higher RPM around 193
: 2,
: : and the Curtiss Wright group went the other way and enl
: ar
: : ged the Cyclone to 1820 ci. Wright got the better engin
: e
: : and the 1820 was in production for 25 years. Pratt and
: Wh
: : itney on the other hand learned the lessons of high spee
: d
: : twin row radials. The (smaller cylinder) bigger twin ro
: w
: : Wrights were not trusted upon introduction (R-1510) unti
: l
: : they went back to big 1820 cylinders, the R-2600, and th
: en
: : the R-3350 emerged and lasted many years. The Russian
: in
: : dustry then had the both successful Wright designs avail
: ab
: : le, the 1820 under production, the R-2600 lend lease and
: c
: : aptured R-3350's to be copied by 1944. The russians (So
: vi
: : ets?) called Mikulin M-25 was an 1820 copy, the ASh-62 w
: as
: : 1812 ci and Cyclone based. The 82 was 2513 cubic inche
: s
: : and about 1850 hp. While it was a new engine, the educa
: ti
: : on came from Wright experience. Direct fuel injection a
: nd
: : engine control units were probably not considered durin
: g
: : the wartime development of the engine. Interestingly th
: e
: : Wright radial probably was the best single engine of the
: e
: : arly 30's period unfortunately causing what some say was
: a
: : reliance on this product. Wright never made it in the
: je
: : t age and P&W still is a household name. (depending on
: th
: : e household)
: :
: : In any case, in wartime, just as in peacetime, a similar
: s
: : hape engine can be used to increase performance. (Allis
: on
: : 1710 to Merlin) Well in peacetime it is to lower costs
: ..
: : .(Bristol Centaurus to R-3350), well that increases perf
: or
: : mance too...Unfortunately there aren't many 801's around
: ,
: : so the ASh sould work pretty well. The interesting thin
: g
: : for me is that the design philosophy of the ASh is from
: th
: : e enemy camp considering what hatched the 801! At 2500
: cu
: : bes there is no comparable smaller diameter Pratt!
: :
: : Joe
:
:
: Very interesting and informative.As you say the R3350 ha
: s indeed lasted many years.On the Moses Lake ramp right no
: w sits Tanker 05 which is a P2V-5 with two R3350-36's and
: Tanker 62,a DC-7 with one R3350-EA1 that has been converte
: d to a DA,one R3350-34 from a Navy Connie,and two -93's fr
: om Air Force Connies.These are all Turbo-Compound models.W
: ith 100/130 fuel instead of 115/145 they are de-rated from
: 3250 h.p. on the DC-7 (3450h.p. for EA engines on DC-7C's
: )and near 3700h.p. wet power on the P2V,to 2880 h.p. We ar
: e also restricted to low blower and no spark advance,altho
: ugh we still use 10% lean at lower cruise power settings.O
: n the DC-7 we use 50"h.g. or 234 BMEP and 2900r.p.m. as a
: take-off power setting.Usually we don't get close to the B
: MEP limit and are closer to 2750h.p. than 2880 using 100LL
: fuel.Interestingly we had a 100LL sample lab tested a few
: days ago that the octane/performance rating was 115.2,so
: it isn't quite as bad a fuel as I had thought.
: As to R-1820's there is a world of difference between t
: he -97 on the B-17 and the -80B on the R4D-8/C-117D.The la
: ter -80 cylinders look like they came from a 3350,while th
: e much older -97 are far less robust.The -80 was rated at
: 1475h.p.(using 100/130)at 54 1/2"h.g. and 2700r.p.m. and t
: he -97 was 1200h.p.(using turbos)at 46" and 2500r.p.m.