Best Japanese fighter

[GregP]

The gauges are not vacuum gauges, they are pressure gauges.

Get into a normally aspirated, carbureted aircraft. Assume the air pressure is at 29.92 unches of Mercury, which you can easily verify by dialing in the field elevation. With the engine off, you'll read 29.92 inches of Mercury, atmospheric pressure ... assuming the field is at sea level. If not, you'll read about 1 inch per 1,000 feet less. So, at 6,000 feet with the engine off, you'd read about 23.90 inches of Mercury before you start the engine.

On takeoff, at full power, you'll read about 1 inch less than ambient presure since the throttle plate is in the flow path. Once you get some speed, you usually regain this lost inch and maybe a little more due to ram air pressure being added to the ambient pressure.

At idle, you'll read about 12 inches or so because the throttle plate blocks the air passage and the pistons create a partial vacuum, but the gauge is reading air pressure in the intake, not vacuum. In a supercharger or turbocharged engine the gauge is still reading pressure.

 

[Shortround6]

They may actually read "pressure" but most CAR gauges on UN-SUPERCHARGED engines are commonly referred to as vacuum gauges and are marked as such on the dial by their makers. Some are calibrated at "0" (normal atmospheric pressure) and work backwards.

Some gauges will show both positive and negative pressure and are called boost gauges.

AIRCRAFT manifold pressure gauges are as you describe.

Again we have to be careful it trying to compare auto or motorcycle practice/experience to aircraft use.

 

[fastmongrel]

The gauges are not vacuum gauges, they are pressure gauges.

.

I work as a car(auto) mechanic and I use a Vacuum gauge and a normal healthy car engine Blown or not blown will show about 18 to 20 "hg at tickover and if you snap the throttle open and release it will drop to about 5 "hg then bounce back. If a gauge showed a atmospheric or plus reading then the engine probably wouldnt run.

 

[GregP]

All AIRCRAFT manifold pressure gauges show pressure. As I stated, they'll read ambient air presure when the engine isn't running. They read less at idle due to partial vacuum and the closed carburetor plate, but 12 inches is still pressure. The vacuum pulled is the difference between ambient and the reading at idle, which will usually run about 12 inches at idle for something in the 360 - 520 cubic inch range Lycomming. So, it's pulling about 17.02 inches of vacuum against 29.92 inches of pressure ... you still get pressure. All you have to do to make it a vacuum gauge is zero out ambient pressure and you've got it. Nothing mysterious about it.

Shortround, the only aircraft gauge in your group is the last one, and it clearly states on the gauge face that it reads in inches of Mercury absolute. That is a pressure unit.

Here is a good explanation: http://www.advancedpilot.com/downloads/prep.pdf

 

[bobbysocks]

you are arguing semantics....it is pressure in the fact it is show you the difference between the ambient air pressure in the manifold vs that of an absolute vacuum. suction vs lack of pressure. right from that website..

Suction, Not Pressure
First, let's get rid of this idea of "pressure," because what the MP instrument of any normallyaspirated
engine really shows is lack of pressure. In short, with the engine running, the MP gauge
is always reading suction -- it's just marked with numbers that don't make that obvious.

It should be clear from this that the intake system of any normally-aspirated engine is nothing
more than a vacuum pump!

 

[GregP]

Yup, there is vacuum on the piston side, but not complete. The 12 inches of pressure inside the intake at idle is exactly that pressure. It is about like being at 20,000 feet. So the pressure difference creates airflow and the venturi feeds the fuel.

As I stated, the gauges in an aircraft are pressure gauges, not vacuum gauges, Go sit in any Cessna, Piper, Mooney, Beechcraft, etc. You won't see an engine manual that specifies vacuum ... they specify inches of Mercury absolute of manifold pressure, not inches of vacuum.

Now, it is true, you CAN retrofit a vacuum gauge and operate it that way if you write your own manual, but you won't buy it that way from a certified manufacturer.

Might be semantics, but you might as well get it right.

 

[bobbysocks]

i have sat ( and flown ) cessnas, pipers, and stinsons. yes, they all had manifold pressure guages.....that showed the reaction of suction to the ambient air.

2a: the act or process of exerting a force upon a solid, liquid, or gaseous body by reason of reduced air pressure over part of its surface

 

[GregP]

When I think a vacuum, I think if testing we did at Motorola down to levels of 10 Torr, not 12 inches of Mercury. To each his own, I guess ...

And yes, it is semantics. A "vacuum pump" in an aircraft doesn't create a total vacuum, it creates a partial cavuum to develop a p[resure differential and run gyro instruments, so you could look at it as vacuum .... but then again, when you test a vacuum pump, you usually use a vacuum gauge, not a pressure gauge. In reality, all you are doing is testing the magnitude of the pressure differential so you can ensure there is enough delta to run the instruments. You could do it with an air compressor, too, but they usually don't for obvious reasons.

Whenever I used to have to buy a vacuum pump, I'd think about that ... and then order the damned vacuum pump anyway ... and curse it until I was flying again. For some reason, Hobbs meters tend to be an issue, too. Must be phases of the moon since nobody was smoking in any planes I flew. Luckiy I had very few actual engine issues ... the only failure I had was in a rental C-172 and it was a partial failure. Somebody had put sugar in the gas tank and I lost power but was able to restart and keep it running using the primer until I got to an airstrip. Then I called the flying club and told them to come pick up both their airplane and me.

 

[Ivan1GFP]

I know we are playing a semantics game here, but what would you call a Japanese or British manifold pressure gauge?
The readings are relative to ambient pressure.....

- Ivan.

 

[GregP]

The British used pounds of boost and used what is essentially a vacuum guage. The same engine in the P-51 uses a manifold pressure guage. I never said you C'T do it, I said it isn't common, especially today.

You CAN use either guage but, here in the USA, you can't find one from a manufacturer with a vacuum giage. In Europe (or anywhere else) today, if you are flying a Piper or Cessna, you are flying a manifold pressure guage.There may well be some European manufacturers who purchase Lycomming or Continental engines and use them with boost guages in their planes, I don't know. If they do, then they are responsible for the engine manual. Most manifacturers use the system developed for use with the engines they source and don't "re-invent the wheel."

The Germans used manifold pressure referenced to technical; atmospheres. Thye Japanese and Soviets used either mm of Mercury manifold pressure or sometimes the German ata (technical atmospheres) unit. Of all the WWII combatants, only the British used a boost (essentially a 2-way vacuum gauge) gauge. When properly calibrated there is no difference and you can convert the units easily. It's just that most of the world uses pressure, not vacuum. If anone just has to use vacuum, by all means vacuum away.

 

[GregP]

If anyone is interested, I can post the formulas to conver among the manifold pressure units. It's easy in a spreadhseet, and takes away the uncertainty.

 

[Aozora]

the beauty and magic of the old norton engines was how well they were ported...which was damn near perfect. i know a guy who races triumph motorcycles....he claims he can gain me 5+ hp with his port job on my bonneville. the better an engine breathes supercharged or not has to have some effect on performance.

My great uncle owned a motorbike he claimed had a Triumph engine in a Norton frame, but I can't remember what it was called; was there such a bike (pardon my ignorance here)?

 

[GregP]

Not too sure about the name, but it would have been the best of both worlds at the time ... though the Norton engine wasn't far behind. Trumpets were quick for the day and light, but the Norton frame and swingarm didn't flex near as much as the Triumph did. NOTHING else flexed like the old 2-stroke Kawasaki 750 triple and the original Kawasaki 900, though ... except maybe the Suzuki 500 twin.

Must have been beer can-grade steel and plastic swingarm bushings(not really).

You'd still have to put up with the Triumph oil leak becasue the oil leaked through the engine case, not from around the gaskets or seals ... the Aluminum was too porous and once the bubbles in the Aluminum filled up with oil ... it sort of migrated to the ground via the bottom of the engine case. Nothing you could do about it. It weeped all the time.

Not too fond of the old carbs either, but fuel injection for bikes wasn't around yet, so they were about near the top of the heap despite the issues. The Tiger and Bonneville were pretty good except for the shifter and brake being on the wrong side. It never got in the way until an emergency, and then you always downshifted whether or not you wanted to do so. Caught me a couple of times and I didn't go down, but it was dumb luck I didn't.

The new ones don't leak through the engine cases (or anywhere else for that matter) and are genuine 150,000 mile motorcycles ... or maybe more. I have one friend with 180,000+ on a new build Triumph with normal maintenance ... but he isn't a racer, just a street rider.

 

[razor1uk]

To keep with the motorcycling sub topic, the 'Bloor' triumphs, built at Hinckley, the original (mid to late) 80's era engines were based upon the mid 80's Kawasaki GPZ900 AFAIK, with enough differences to not cause patent conflicts - like 3 cylinders (except for the 1200 4's used in the Trophy/Daytona 1200) and differing dimensions of bore stroke, crank throws, rod lengths, distances between the inlet and exhaust cams to the crank etc..

The newer 509 and other new Triumph engines should be just as good - I love the 675 Triumph motor, it partially inspired the new 'MV' to make a baby triple...

Well Kawasaki might have not been to bothered too much, since their original Meguro name W6 (or W12?) was almost a pure copy in ethos to a BSA (AMC) A6/10 with some Triumph alike engine details, both the English engines I believe, were Edward Turner designed; or as Chief Engine Designer/Engineer the 'signer-off' for the work the engine team did most of the Brit twins engines for most of the 30's - 60's British manufacturers at one time or another.

So the Hinckley ones with regular servicing, should be capable of theoretically GPZ900 ZZ1100 heard-of milages of over 200,000 engine-wise.

 

[Gixxerman]

Not too sure about the name, but it would have been the best of both worlds at the time .

AFAIK they were commonly referred to as 'Triton's' (certainly all the mags I've read here use the term often).

NOTHING else flexed like the old 2-stroke Kawasaki 750 triple and the original Kawasaki 900, though ... except maybe the Suzuki 500 twin.

The weird thing is many reviews these days often say they're not that bad, nothing like as good as the modern stuff of course but I always had a feeling that for journo's riders used to British Italian machinery the big Japanese 2 strokes were so different they got a bad name.
I was raised on them (although the Kawasaki H1 500 H2 750 were bikes I never got the opportunity to sample) but I rode and/or owned all the other Kawasaki triples the Suzuki GTs at one time or another. If you were used to them ( carried out a couple of simple mods - decent shocks were a must) they weren't that bad.
Funnily enough I did try out a BSA A65 Lightning once to me it was the different one with odd feel.

The Tiger and Bonneville were pretty good except for the shifter and brake being on the wrong side. It never got in the way until an emergency, and then you always downshifted whether or not you wanted to do so. Caught me a couple of times and I didn't go down, but it was dumb luck I didn't.

Ah but to us over here it was, back then, the correct side...although obviously as Japan's influence the demands of the US market became a big factor we changed.
I know what you mean tho Greg, if you're used to a left-foot gear change right brake it can be downright dangerous, as someone used to your layout pattern on Japanese bikes riding older British machinery was um 'interesting' sometimes because of it.
I suppose if you owned one for a while it would just become 2nd nature.

To keep with the motorcycling sub topic, the 'Bloor' triumphs, built at Hinckley, the original (mid to late) 80's era engines were based upon the mid 80's Kawasaki GPZ900 AFAIK, with enough differences to not cause patent conflicts - like 3 cylinders (except for the 1200 4's used in the Trophy/Daytona 1200) and differing dimensions of bore stroke, crank throws, rod lengths, distances between the inlet and exhaust cams to the crank etc..

Indeed, modular design was their objective a pretty sound strategy at that.
Choosing a sound design for basing their initial models (the GPZs you mentioned are undoubtedly where they began) has indeed led to excellent reliability coupled with good performance.
Not at all bad considering what they started from.

In reference to GregP's comment about porous alloys I have read that the Bloor manufacturing used a resin to seal the alloy as they were manufactured.
I have never read anything other than they were ( continue to be) as good as anything out there, finally the jokes about 'Royal Oilfields' and so on are a thing of the past

The newer 509 and other new Triumph engines should be just as good - I love the 675 Triumph motor, it partially inspired the new 'MV' to make a baby triple...

Not a bad compliment, eh?
I think they also influenced Benelli with their Tre900 triples too.

 

[parsifal]

Im surprised no-one has mentioned the Kyushu J7W Shinden. Admitedly a prototype, but it did fly during the war

Performance

Maximum speed: 750 km/h (469 mph)
Range: 850 km (531 miles)
Service ceiling: 12,000 m (39,360 ft)
Rate of climb: 750 m/min (2,460 ft/min)
Wing loading: 240.4 kg/m2 (49.1 lb/ft2)
Power/mass: 0.32 kW/kg (0.20 hp/lb)
Armament


Guns: 4× 30 mm Type 5 cannon
Bombs: Up to 120 kg (264 lb) bombload


View: https://www.youtube.com/watch?v=hJs1O2HSosE

 

[Shortround6]

My great uncle owned a motorbike he claimed had a Triumph engine in a Norton frame, but I can't remember what it was called; was there such a bike (pardon my ignorance here)?

They were called "Tritons"

Triton motorcycle - Wikipedia, the free encyclopedia

 

[razor1uk]

The beautiful Kyushu J7W Shinden; 'though it had cooling issues with its engine - possible an ex raiden/jack 'long case' unit.

Certainly it is a craft of 1946 'what if ' candidate for top spot - although the flying prototype wasn't armed AFAIK. There's likely to be one rusting away in a Smithsonian hanger somewhere if it wasn't recycled.

 

[GregP]

As far as I know it made exactly two flights, both with the same pilot. The aircraft vibrated fiercely (probably the long drivesahft but maybe an unbalanced prop) and was never flown again. I'd be hard-pressed to say it was even close to flightworthy. So maybe it had potential, but wasn't ready for anything when the war ended. Perhpas it could have been developed and perhaps not ... I don't know.

Looks futuristic, but I could not say whether or not it would have been even a passable service aircraft. Maybe a jet version ... and maybe not. I like to think it could have been developed but that would be venturing into the realm if a "what-if," and I usually decline to go there because there are no answers that can be shown to be right or wrong with historical fact, so anything can be claimed.

At lest we know the Me 163 / J8M flew well when powered by rockets. That makes me suspect they would fly well with a jet engine, too, but nobody can really say. They never made one.

Still, I like the J7W and hope it could have been made to work.

 

[Aozora]

They were called "Tritons"


View: https://www.youtube.com/watch?v=hJs1O2HSosE

The engine installation: