Scudrunners

I wish I had the quarter million to get my Ricky Bobby on in this beast:
https://anchorage.craigslist.org/avo/d/ ... 92437.html

It was designed and mostly built by a pro before he passed, his client specified that it was to be competitive at Reno against the warbirds.  Now it looks like it’s being parted out before even flying.  Looks like it would be a hell of a rush to go up in, like a budget(?!) Tigercat.

400hp IO-720 was used in single Comanche 400 IIRC
and was not very popular.  Also Helio Courier maybe,
but they put everything except the kitchen sink into that.

I shudder to think of the resonant torsional harmonics
of that long, whippy crankshaft.  There might be several
RPM's that you really want to avoid at all costs.

[quote author=Colonel Sanders link=topic=9447.msg26360#msg26360 date=1547097977]
I shudder to think of the resonant torsional harmonics
of that long, whippy crankshaft.
[/quote]
Shouldn't be any worse than a V-8 and those are common enough, no?

Never seen an automotive V-8 without a harmonic balancer on the front of the crankshaft.

Even worse would be an inline aka straight 8, popular before WWII in high-end cars.

[img]https://upload.wikimedia.org/wikipedia/ ... -5-2-6.gif[/img]

Look at that crankshaft!!

https://en.wikipedia.org/wiki/Straight-eight_engine

[quote]A straight-eight can be timed for inherent primary and secondary balance, with no unbalanced primary or secondary forces or moments. However, crankshaft torsional vibration, present to some degree in all engines, is sufficient to require the use of a harmonic damper at the accessory end of the crankshaft. Without such damping, fatigue cracking near the rear main bearing journal may occur, leading to engine failure.

... due to the length of the engine, torsional vibration in both crankshaft and camshaft can adversely affect reliability and performance at high speeds. In particular, a phenomenon referred to as "crankshaft whip," caused by the effects of centrifugal force on the crank throws at high engine rpm, can cause physical contact between the connecting rods and crankcase walls, leading to the engine's destruction. As a result, the design has been displaced almost completely by the shorter V8 engine configuration.[/quote]

People ask me for my religion, and I don't really have an answer, except
that I grew up in the Church of the Internal Combustion Engine.  Unfortunately
I always get a dirty look when I say that, which too bad because I already
have one.

holy crap WTF is that thing, looks like its doing mach 2 on the ground.

What would that thing be like on one engine? It's fairly long but has a tiny looking rudder. Must have a lovely Vmc.

I feel like you'd get better performance out of some of the really bonkers Lancairs.

https://arstechnica.com/cars/2018/08/40 ... otorsport/

750 hp out of am IO-550?! Sweet baby Jesus. This twin things only beats him by 50 HP but probably has a good amount more weight and drag.

A pair of IO-720 reminds me of the multi-row radials on the Lockheed Constellation
after WWII.  The ultimate development of the four-stroke internal combustion
engine, and completely obsolete.

[img width=500 height=333]https://c1.staticflickr.com/9/8547/3026 ... a3b2_b.jpg[/img]

https://en.wikipedia.org/wiki/Wright_R- ... ex-Cyclone

Replace two ornate piston engines with one powerful, light, compact, reliable
turbine.  See TBM 700, PC-12, etc.  Less drag, too.  Get rid of the huge lumps
on the wings.  You're already paying for the wetted area of the fuselage.

I like the Legend, with the Walter, PT-6 or Garrett.  Composite fuselage,
turbine spinning a prop.  Receipe for a grin on your face and registered
letters in your mailbox.

More internal combustion madness:

https://en.wikipedia.org/wiki/Pratt_%26 ... Wasp_Major

[quote]The Pratt & Whitney R-4360 Wasp Major is an American 28-cylinder [u]four-row[/u] radial piston aircraft engine designed and built during World War II, and the largest-displacement aviation piston engine to be mass-produced in the United States.

It was the last of the Pratt & Whitney Wasp family, and the culmination of its maker's piston engine technology, but the war was over before it could power airplanes into combat.

It did, however, power many of the last generation of large piston-engined aircraft before turbojets, and equivalent (and superior) horsepower turboprops (such as the Allison T56), supplanted it.

The four row configuration had severe thermal issues that decreased reliability, with an intensive maintenance regime involving frequent replacement of cylinders required as a result.

Large cooling flaps were required, which decreased aerodynamic efficiency, putting extra demands on engine power when cooling needs were greatest.

Owing in large part to the maintenance requirements of the R-4360, all airplanes equipped with it were hugely expensive to operate and suffered decreased availability.

Its commercial application in the Boeing Stratocruiser was unprofitable without government subsidy.[/quote]

This will probably get me shit on, but I like single-row radials.  A fuck of a lot easier to work on.

I've always figured the most 'hotrod-able' of the big engines is the P&W R-2800.  I remember reading a good account of when P&W was developing the CornCob R-4360, each time they were about to do a test run at a higher horsepower, the guys on the R-2800 team would do some mods to their test engine and beat the other team to that power level.

https://www.historynet.com/r-2800-pisto ... ection.htm
"Too bad the Reno racers didn’t have the help of Pratt & Whitney’s engineers. When during the early years of World War II the company began work on the 28-cylinder corncob, the team that developed the R-2800 kept competitively boosting the power of its test engines to 3,000 hp, and then 3,500 and ultimately 3,800 hp with the help of water injection (to cool the intake charge) and stratospheric amounts of supercharging. The R-4360, however, eventually went on to produce a semi-reliable 4,300 hp."

The Wright R-3350 is a good one to be sure, Rare Bear and September Fury are testaments to that.  Dreadnaught with the R-4360 was engineered for 450 mph and it has done exactly that speed for decades, but never more.  I believe the ultimate unlimited at Reno would be an upsized Nemesis NXT with a hotrodded R-2800.  Should go like a scalded cat.

Gerry