the World would be more Diesel-punk
Not big Rocket or manned space flights
This is a 50/50 in my opinion. Prestige considerations still carry weight in a multipolar world, and the development of nuclear weaponry will surely spur the development of ballistic missiles from the larger more or less "amateur" efforts (like Goddard's), which will provide enough capability for orbital launch, as demonstrated by the large number of IRBM and SRBM-based launch vehicles (eg., the Delta, Jupiter-C, Kosmos...) Moreover, by the 1970s and 1980s, space launch (albeit not of a particularly useful payload) should be in the funding range of rather small groups, using collections of existing probably military-derived engines, to produce vehicles similar to the Scout or Lambda.
The obvious economic and military applications of space would then take over once launch itself was demonstrated to spur further development, although space would likely be significantly behind OTL. What would particularly suffer would be scientific spaceflight; before World War II, most scientific research was funded by private individuals, foundations, and corporations, which are not likely to fund the expensive pure science missions we've seen OTL like the Vikings, Hubble, Curiosity, and so forth. I'd be impressed if anything more than Earth and Sun-focused missions existed ITTL. Certainly I wouldn't expect high-energy astronomy to be much ahead of where it was in the 1960s OTL by 2012 ITTL, and equally I suspect there won't be much luck for infrared and microwave space observatories.
today Computers would big clumsy things in size of a house or a skyscraper, if they use radio valve instead transistors.
with those sluggish computers, you don't have a internet or do high end simulation for science or industry like in aerodynamics
This is extremely unlikely. AT&T--a completely private firm--always, before the breakup of the Bell System, invested very heavily in computer technology, not terribly surprising given the complexity of the systems it was controlling. It's no accident that the first practical transistors, a number of important processes for manufacturing semiconductor components, the first photovoltaic cells (a technology related to semiconductor devices like the transistor), the first charge-coupled devices, C, UNIX, and C++ were all invented at Murray Hill. If anything, without the permanent intrusion of government into scientific research (previously dominated in the United States by private donors, like the Rockefellers, and private firms, like AT&T) caused by World War II and the Cold War, and the corresponding diversion of scientific talent towards military and pure research, the development of modern computers might be
advanced relative to OTL (that is, the first computer might come later than Colossus or ENIAC, but it will likely
start with transistors, rather than tubes).
Where not having WWII or the Cold War will make a
big difference is the development of computer internetworking. Networking will surely be developed, since it is an obvious, powerful method of improving the performance of multiple computers, but it is likely to originate in corporate internal networking and telecommunications firm developments rather than in a government research project. This means a likely significantly different underlying architecture (perhaps based on virtual circuits and other telephone-like architectures rather than packets) and a considerably more divided and "walled garden" "Internet" (if, indeed, the Internet exists
at all; although it does seem probable that some sort of home computer networking system will be developed, it may be more like Minitel than the Internet...)
Aircraft have to be tested as model in wind tunnel or build prototype were pilot risk there life to fly it.
i have my doubt that the Jet-engine is accept by Aerospace companies, even yes it will take decades for that.
Nothing like that long. Jet engines were rejected in the 1930s because they represented a large technological leap for a doubtful advantage (how useful was the Meteor relative to the Spitfire, for instance?). I mean, piston-engine aircraft didn't become totally obsolete for military applications until the early-mid 1950s, some twenty years later. Even ITTL, upgrades demanded by commercial firms and the general march of technology would mean that piston engines would be pushing reasonable limits on their output by the late 1940s and early 1950s, while jets would have become much more practical. I have been told that turbochargers were actually producing much of the thrust of later piston-engine designs, and they are certainly similar in many respects to jet engines; if so, then there would be obvious technological transfers from one to the other.
The biggest change to science and technology would come from drastically reducing the investment provided by government to scientific research, particularly in the United States (obviously, the Soviet Union for instance would still have significant governmental R&D efforts). Prior to World War II, as I mentioned above, most scientific research was still funded by private organizations and persons, who of course have generally more limited funding than governments and more practical goals, with some notable exceptions like Bell Labs. While I don’t expect government to stay out of research forever, I expect that where it does enter it will be pretty strictly focused on “practical” areas, like medical or military research. Where this is particularly important is when it comes to expensive research with few practical applications, like astronomy, planetary science, or high-energy physics, which IOTL have depended heavily on governmental funding since at least the 1960s for continuing development. I find it doubtful that missions like Hubble, IRAS, COBE, Voyager, etc. would have flown without significant government investment, and equally doubtful that accelerators much past the GeV scale would have been built without US, Soviet, and European investment in the technology.
What this means is that a number of fields, such as cosmology and high-energy physics, are likely to be far, far behind their counterparts IOTL. For example, quantum field theory, at least at the QCD level and even in significant parts of the electroweak level is likely to be regarded much as string theory today--largely a mathematical curiosity which has no realistic prospect of experimental testing. People will be trying to do indirect tests at the so-called "intensity" and "cosmological" frontiers, but those will themselves have issues.