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  • Users: Pkruse
  • In Aerospace Engineering
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  1. P

    Man-made vs natural flight

    This should be an interesting discussion. I look forward to following it. But one thing to consider is that with airplanes, the speeds are much higher. That means that sudden changes in direction or speed are seriously limited by physical considerations of F=ma. Some aircraft will routinely...
  2. P

    Thoughts balloon rocket launch

    Launching from altitude saves on total fuel required to reach orbit. Balloons can go much higher than you indicate. But so far, taking an airplane ride for an air launch seems a better idea. A few systems have done that. They can be placed with more precision and they can impart an initial...
  3. P

    Propulsive Efficiency

    At cruise, the ideal would be to have an exit velocity one mph higher than the air speed. We can’t quite do that, but that is the theory. The most subsonic engine would be to have a large fan with as high of a bypass ratio as possible. Then nearly all the thrust will be from the huge mass of...
  4. P

    Will electric motors ever propel a 747?

    Ryuk1990: Two things are true in that article beyond dispute. He is not an aeronautical engineer, and this will be much more difficult than designing a spacecraft to dock with the ISS. Everything else he says can be debated. But he has proven himself extremely adept at identifying excellent...
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    Will electric motors ever propel a 747?

    Ryuk1990: Yes and no. I have a friend who is a professor of chemistry at UCF, as is his wife. They have been working exclusively on battery development for 40 years. Certainly, these are the people who develop new technology. But to me working a real project on a real airplane, I'd expect...
  6. P

    My first Space X Launch Experience

    I'll first state what I know, and then tell you my best guess as to how this works. They advertise that they can still make orbit with 2 or 3 engines shut down. They are also carrying less than 10% of full capacity. So they clearly have lots of reserve engine capacity. Guessing: With...
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    Will electric motors ever propel a 747?

    The goal at cruise for an airliner is for the fan exhaust to be one mph more than air speed. Can't really do that, but that is the theory. If the outside of the exhaust flow approaches that, it is OK for the center of the flow to be faster. They also shape the nozzle for smoother and more...
  8. P

    Will electric motors ever propel a 747?

    Where does the FOD come from in an airborne launch? Birds and hail? We can design for that. Not much different from a conventional propeller. Take a look at the new PW geared turbo fan. It enables a much higher NO ratio.
  9. P

    Will electric motors ever propel a 747?

    Magneto speaks well, but his turbine course is a bit obsolete. Don't hold that against him. Billions are being spent on research and development, and we learn new things all the time. The greater the bypass ratio the better for many reasons. So we make it as big as possible within physical...
  10. P

    My first Space X Launch Experience

    I had an opportunity to talk with an old jet and rocket engineer, who is still working and is very sharp. His specialty is the aerodynamic analyis. He pointed out that I already knew that in a jet engine, the high noise comes from the rapid and forceful mixing of the exhaust with ambient air...
  11. P

    Will electric motors ever propel a 747?

    I'm a turbo machinery design engineer working with gas turbines and jet engines. I'm pretty sure that with the right team, I could design and successfully market an electric engine for the 747 if the electrical engineers could first do two things for me: Give me a battery with the same energy...
  12. P

    My first Space X Launch Experience

    I saw my first Space X launch from near Cape Canaveral. I've been watching launches since 1966, and this was by far the quietest of this size vehicle that I've ever heard. How do you suppose they made it so quiet?
  13. P

    Gears vs. sprockets. What should I use?

    I've seen belts transmit 600 HP at 3600 rpm. They make planetary gears to step down a turbine, sometimes in two or three stages. Any of these can be high efficiency. I've seen a turbine planetary with more than 99%. But that was a rather special design that took 15 years to develop.
  14. P

    Gears vs. sprockets. What should I use?

    I've seen chains used to transmit as much as 700 HP at 900 rpm. The choice is often bases on space available. Also, higher speed applications tend to work better with gears.
  15. P

    Hypersonic test fails

    They are developing completely new engine technology that will not only be very fast, but also fuel efficient and quiet enough to fly out of civilian airports. They are also learning how to quiet the sonic boom. This thing is pushing current technology on all fronts.
  16. P

    Turbine Engine Questions: Squealer Tips & Classified Weights?

    I would understand that to mean they got information from people with access to unpublished information, but without the authority or permission to release it.
  17. P

    What area of aerospace?

    Gas turbines might interest you
  18. P

    Gas turbine fuel/air ratio 7 cooling, help please!

    Everyone who designs gas turbines makes the turbine inlet temperature as high as the customer is willing to pay for because that makes the engine more efficient. This means a bunch of cooling air. This does not lean out the methane combustor because the cooling air does not pass thru the...
  19. P

    Gas turbine fuel/air ratio 7 cooling, help please!

    Willgoat is right. With the turbine inlet temperature hundreds of degrees hotter than the melting point of the super alloys, the vanes and blades simply must be cooled. Any gas turbine engineering department will have a group of engineers to do secondary flow and heat transfer calculations...
  20. P

    Rockets and kinetic energy or: Why do rockets (Space Shuttle) have rising accel?

    At lift off, the Shuttle has only a little more thrust than weight, so it moves very slowly. The thrust of the solids, where most the mass is located is proportional to burn rate, so they are designed to burn much faster at first, then they slow down quite a bit after they dump much mass. At...
  21. P

    Anyone Studying Combution

    The company I work for sells test rigs for studying combustion in gas turbines. The people who buy them invest millions to study combustion, and have been collecting data for decades. But it is proprietary so they keep it to themselves. If you want access to this knowledge base, you might...
  22. P

    How exactly does a gas turbine engine produce thrust?

    I need to correct or clarify my earlier post. Most the thrust of most engines come from the fan. But some of it does come from the exhaust, especially in the case of a turbojet that has no fan. I will design a nozzle, but another group will determine what the shape of the nozzle...
  23. P

    SpaceX SpaceX Makes History As First Company to Dock a Spacecraft At ISS

    Why is this being held up as such a historic trend setter? Everything else that NASA has flown was developed by a private company, using a generous amount of NASA money. Often, the contractors are also paid to operate the system. That is exactly the same business model that SpaceX continues...
  24. P

    Aeronautical engineering requires a formulaic process of thought!

    I've been in aerospace since 1979. True innovations are rare, but they do happen. Then they will be optimized in small increments for decades. When they do happen they are closely guarded proprietory secrets and you won't see them in the universities until they become old news. Much is...
  25. P

    Airfoil Design Research

    I've floated more than 120 tons on a similar device. They are available commercial off the shelf and are used for industrial applications. But it took more than a million dollars of engineering and shop time to make it work. I agree with Boneh3ad on this one. But if you want to know...
  26. P

    Design Of Axial Compressor

    What do you need to know?
  27. P

    What are booster stages in aviation Gas Turbine

    I design gas turbines, & I've never heard that term for turbofans. Only has meaning to me with regard to rockets.
  28. P

    High performance rockets

    It is mostly a question of how much the fuel weighs, its energy content, and how far you have to carry it. That is why solids are only used on the first stage and all upper stages are hyperbolic. All others are used in between. Apollo first stage was kerosene, then H2, then hyper. Only hyper...
  29. P

    Biggest differences between aerospace and mechanical engineering?

    Some do, some don't. I've been in aerospace for 35 yrs. In my current job, we have 3 guys doing strictly aero work. About 150 are doing various aspects of mechanical, many with aero degrees. About 30 are doing design drawing. All aspects of mechanical are represented.
  30. P

    I have questions for my Engineering Interview.

    BTW: The math is much easier on the job than in the class room. A few analystical jobs might be very math intensive, but I've never had a need to know anything about Calculus in any of my jobs. I just needed to learn it so I could understand what to tell the computer to do, and to determine...
  31. P

    I have questions for my Engineering Interview.

    • Where did you go to college? UCF, Orlando, FL, USA • What degree(s) do you have? BSE, Mechanical • What field of engineering do you work in? Aerospace, mechanical design of the power plant • What are some specific jobs in this field? All aspects of engineering are represented in...
  32. P

    Exploring Non-Rocket Based Atmospherical Launches

    Putting people on a cargo litter greatly increases cost. Worse in the case of the SS is that processing tasks were serial not parallel. All proposed lifters fix both problems and will be much cheaper.
  33. P

    Exploring Non-Rocket Based Atmospherical Launches

    As long as we are off topic: The Space Shuttle proved that a reusable launch system is a whole lot more expensive than an expendable system. Certainly, we could make vast improvements to what we did with the Space Shuttle, but it would still be more expensive because we have also made great...
  34. P

    Exploring Non-Rocket Based Atmospherical Launches

    Back in the 60's & early 70's Gerald Bull experimented with launching packages into orbit with a giant cannon. He demonstrated that he could attain enough energy for the task, but could not control the orbit. Packages were small, and back in those days satellites were big. So it was not a...
  35. P

    Use of Design point for a gas turbine engine

    I'm confused as to what you are trying to do. The customer will specify the design point. Normally is is something like a sea level take off under full load. Then they will request best performance on various secondary points. Then you discuss trade offs. On a commercial airline...
  36. P

    How exactly does a gas turbine engine produce thrust?

    An engine may have one, two, or three shafts to which the blades are attached. Each shaft has one thrust bearing located near the front end. The thrust loads are transmitted from the shaft to the case structure through the thrust bearings. Vanes are stationary, and those loads are...