I was taught ultrasonic testing by a guy who pioneered it post war, his name still thows up results on google searches, C.J. Abrahams. Once in the practical class a guy said "I have found a defect" and got a prompt slap "upside the head". Mr Abrahams informed his student that he had found an indication, it is engineers who decide what is a defect, not technicians.
XP-65/F7F Development
- Thread starter Zipper730
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
On a dark, pitching, wet, windswept deck, you're third in line for catapult two, on a hot scramble with bogies inbound and your AI radar fails its BIT checks, you've got more than an INDICATION! And no engineers to be found; you better hope your tech has his FM on.
Cheers,
Wes
wuzak
Captain
Huh?
In a previous post you said they didn't have the money to develop so many engines. Who were the they you were talking about?
In any case, I should have just said the USAAC funded the programs.
What existing cylinder?
The Curtiss Conquerer/V-1570 from 1924?
You don't build a next generation engine based on last generation cylinder designs.
In the beginning there was only the Continental hyper engine supported by the USAAC. Lycoming started their development a year or two later, using their own funds for development until the USAAC started funding them a few years later.
Chrysler started their program some years later, not sure how they were funded.
In any case, the USAAC was initially funding only one hyper engine for the first few years.
I don't know about the number of "layers", but funding had to be approved before Continental would move onto the next development stage.
Most likely 2 way, but he who signs the check has the last say.
NACA cowlings held little interest for developers of in-line engines.
The theory with flat engines was that the engine could be buried in the wing of a multi-engine aircraft, and only a small protrusion carrying the prop shaft would be external. The theory was that the drag would be reduced in this manner.
It was found, however, that the difference between a normal nacelle and the buried configuration was minimal.
So, the Continental was developed into an inverted vee.
And Lycoming realised that the engine would not be powerful enough for future aircraft, so they put two of their flat 12s together to get the H-2470.
- Thread starter
- #44
Yeah...
That's a good point: I just was wondering if it was possible to use off the shelf components.
Okay, so Lycoming was partially on internal funds, and later on USAAC funding?
Which engine was this?
Okay...
Did this have to reach Congress each time?
That's good
And the nacelle protrusion was minimal so it wasn't worth it. When did they realize this?
Last edited:
Different fields and different discussions. What is a problem in one place, is not in others but sometimes is a disaster one time and one place. With regard to my post , what is defective is decided by engineers, I attach a link discussing a 6 inch crack in a pipeline. There is, I would stake my life on it no crack, especially a 6 inch crack in any pipeline. All pipe line specs are simple in this regard "No cracks are allowed" and that doesn't have a minimum size limit. On an operating pipe line no cracks can be allowed but in other areas of pipeline technology like pump stations they are allowed up to a certain limit and other technologies are developed to cope or monitor. The previously mentioned C.J. Abrahams developed fixed ultrasonic systems which monitor cracks to see if they are propagating or "as built" in a casting.
Pipeline which brings half of UK's North Sea oil is shut | Daily Mail Online
wuzak
Captain
Doubt it went to Congress at all, except, maybe, for yearly appropriations.
wuzak
Captain
Shortround6
Major General
The Army's "method" of funding these programs was to specify a certain goal or performance level. Like saying a test cylinder had to run at a certain level of power for a specified time. Let's assume a goal 75hp for the cylinder (ultimate goal would be about 100hp per cylinder) for 20 hours. If the engine failed ( broke connecting rod for example) at the 19th hour the Army would pay nothing until the engine was repaired, rebuilt and the test started again from zero hours and successfully completed. No extra funds would be paid for the rebuild or the extra hours of testing. Then the Army could decide the next test would be at the same level of power for more hours or raise the power level or decide that a bigger valves are required or some other change and issue a new contract with details of the new test. You could have a number of different tests/contracts in one year.
Anything over and above what the Army wanted/ was willing to pay for, was at the manufacturer's risk. Like building a two cylinder test rig, very useful for figuring out the crankthrow and connecting rods on any engine using two cylinders per crankthrow. Army did move to two cylinder test rigs.
Army apparently didn't think of the complications of sticking 6 pairs of cylinders together. To be fair a lot of engine designers failed to appreciate the complexities of adding cylinders or running engines at different rpms that originally designed for. Or the fact that higher rpm engines over more opportunity for harmonic vibration. As a result the army didn't "fund" a 12 cylinder engine until very late in the development cycle.
Anything over and above what the Army wanted/ was willing to pay for, was at the manufacturer's risk. Like building a two cylinder test rig, very useful for figuring out the crankthrow and connecting rods on any engine using two cylinders per crankthrow. Army did move to two cylinder test rigs.
Army apparently didn't think of the complications of sticking 6 pairs of cylinders together. To be fair a lot of engine designers failed to appreciate the complexities of adding cylinders or running engines at different rpms that originally designed for. Or the fact that higher rpm engines over more opportunity for harmonic vibration. As a result the army didn't "fund" a 12 cylinder engine until very late in the development cycle.
- Thread starter
- #49
Thanks
That engine started development in 1940: Which seems well after the Continental O-1230/IV-1430 and Lycoming O-1230 designs; Pratt & Whitney submitted several ideas as well right?
I'm curious about two things: Firstly, how did the USN compare? Secondly: Could the US Army alter the contract partway along?
Why?
Perhaps it wasn't immediately obvious that a demo of one or two cylinders working on a test bed gave very limited information on how a complete engine would work at 25,000 ft.
Or even at all.
Cue the Ford V-1650 - two cylinder test mule worked great, however the complete V12 produced less than half of projected power.
Let me guess. The test mule was fed compressed air at room temperature and the mule wasn't driving the compressor?
There was only one engine called "HYPER" and that was the Continental I-1430. This turm has since come to mean any of the high performance liquid cooled engine of the period. But no period document will do so.
It should be noted that, unlike the other liquid cooled engines, the I-1430 was actually designed by the army. Continental was a subcontractor hired to build and develop the engine. This is why they spent four years on single cylinder testing. There was a considerable amount of extra red tape in the way.
It should be noted that, unlike the other liquid cooled engines, the I-1430 was actually designed by the army. Continental was a subcontractor hired to build and develop the engine. This is why they spent four years on single cylinder testing. There was a considerable amount of extra red tape in the way.
In terms of developing an engine I believe the industry as a whole was learning about learning. It may have seemed reasonable to some to only finance one cylinder for research or possibly a twin, but for example Rolls Royce were developing the Crecy engine through the thirties and forties (a sleeve valve two stroke) by the time the project was abandoned a total of 6 complete V12 engines and 8 additional V twins had been made. I don't see how you can conduct long term reliability and short term maximum power tests on the same piece of "kit" doing one invalidates the other.
wuzak
Captain
Engine development starts with a single cylinder development engine to this day.
The Crecy was based on Ricardo's single cylinder test engine, though with some changes.
The V2 development engines were produced to test the sleeve drive mechanism, which could not be done with a single cylinder engine. At least the first V2 was before the first V12.
The Crecy was based on Ricardo's single cylinder test engine, though with some changes.
The V2 development engines were produced to test the sleeve drive mechanism, which could not be done with a single cylinder engine. At least the first V2 was before the first V12.
wuzak
Captain
The I-1430 was based on the Army's "hyper" cylinder design.
This meant hemi head and 2 valves per cylinder.
The O-1230/H-2470 was developed based on the same architecture, as was the Chrysler IV-2220.
I don't doubt that at all, I was just making the point about the scale of research needed. Research may be based on single or twin cylinder prototypes but not just one and that research just gives background info for a multi cylinder engine.
Shortround6
Major General
The Lycoming may not have been referred to at the time as a "Hyper" engine but it was developed at almost the same time, to the same goals, using very similar architecture and principals. And by Continentals main rival.
The Chrysler was around 8 years later and use somewhat larger cylinders. In fact the cylinder was about 1 cu in larger than a Merlin Cylinder
I would agree that the Chrysler's claim to be a hyper engine is very, very dubious.
I don't believe the Allison was ever referred to as a "Hyper" engine.
Shortround6
Major General
A lot of companies started with one cylinder test rigs. What happens after that depends on the engine. V-12s, V-8s, flat engines can get some good information from a two cylinder rig. The two cylinders act on one crank throw and will test the connecting rod and bearing set up.
Radials see a lot less benefit from two (or three?) cylinder test rigs. P & W for example sometimes built one row test engines of two row radials as it allowed testing of the master rod/slave rod set up. and any vibration problems of the single row (adding the 2nd row introduced a whole bunch of new vibration problems)
For the V-12 building a V-4 or V-6 won't really tell you much. The crankshafts will be too short and too stiff to reveal the problems that will show up with a full length crankshaft.
I have no idea if RR ever built a 4 cylinder test rig for the Vulture.
Radials see a lot less benefit from two (or three?) cylinder test rigs. P & W for example sometimes built one row test engines of two row radials as it allowed testing of the master rod/slave rod set up. and any vibration problems of the single row (adding the 2nd row introduced a whole bunch of new vibration problems)
For the V-12 building a V-4 or V-6 won't really tell you much. The crankshafts will be too short and too stiff to reveal the problems that will show up with a full length crankshaft.
I have no idea if RR ever built a 4 cylinder test rig for the Vulture.
