Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  • Users: GraviMan
  • Order by date
  1. GraviMan

    Pipe bending software.

    If we are talking CAD there are lots of 'em. EDS Master Series is pretty good (if user intimidating). Catia V5 is the industry standard. Pro-Engineer is good for powertrain stuff. You could try solid edge solid works. There are plenty of budget 3D cad packages, but i've never really needed to...
  2. GraviMan

    Value of Engine Efficiency??

    "Graviman, my own country is in a similar position re climate change, but we are perhaps straying too far from the topic?" We were doing a cost/benefit analysis of more economical engine development... Mart
  3. GraviMan

    Value of Engine Efficiency??

    "...I would agree that for the UK road conditions that I experienced SUV's would be contraindicated simply for parking/road width/fuel useage issues." Well, RPMag, my concern is really with the CO2 emissions. My point is that someone driving an SUV in the US of A, is having a direct affect on...
  4. GraviMan

    The Future of Rotorcraft

    "I question that HHC offers much improvement to the rotor performance..." I've not done a lit search, but HHC was originally done by Sikorsky (i think) to reduce vibration. What they found was that by allowing blades to follow local streamlines more accurately, the rotor torque went down...
  5. GraviMan

    Value of Engine Efficiency??

    Just for reference sake in the UK we pay approx $1 US per litre, and it's still rising. Our country is entirely dependant on the Gulf stream for it's warm climate (ie will be first affected by global warming). The average commute to work (in the south) is 50 miles or more, and house prices are...
  6. GraviMan

    The Future of Rotorcraft

    Hi Dave, Looking at Stepniewski&Keys, i can understand why you recommended it. I've got some other stuff to study first, but i'm gonna enjoy reading it. Hopefully i can then offer more help get your project off the ground. In the mean time i'll keep asking questions. :-) Mart
  7. GraviMan

    Signal Noise+Exhaust emisson

    I gather you are talking about exhaust noise transfer functions and sound emissions? Exhaust NTFs are just a way of determining the output sound pressure level divided by the input spl. It is generally shown over the frequency domain. Since most exhaust systems will be used with a number of...
  8. GraviMan

    The Future of Rotorcraft

    As I was saying, before my toes were trodden on. Since i understand from your site that you are considering higher harmonic control, it may be worth investigating electrical servomotor control for the tips. This would allow IRTC and high speed flutter control. Mechanical is equally possible, but...
  9. GraviMan

    The Future of Rotorcraft

    ..."As always, constructive or destructive criticism solicited." I am actually very impressed with the way you are going about the unicopter design. To many ideas get tied up in patent b*ll, before they have a chance to succeed. I have never seen your approach, and i hope it pays off. :-) Mart
  10. GraviMan

    The Future of Rotorcraft

    Trouble is even these still don't answer my main concern. Perhaps i should explain it another way... If RRPM was extremely low, and chopper speed was very high, at a given instant in time the rotor assy could almost be considered stationary. If a blade is stationary above the canopy, then the...
  11. GraviMan

    The Future of Rotorcraft

    BTW, how do you find the time to put so much work into Unicopter & Synchrolite?!? Is it a project you are doing on your own or is there a collective? I have recently placed an order for the various recommended reading on single rotor, counter-rotating, and convertiplane helicopters. I intend to...
  12. GraviMan

    The Future of Rotorcraft

    I've had a brief (lunchtime) look at the reverse velocity utilisation, but it doesn't answer my main concern. Chopper blades normally have the airflow at the tips flowing from the leading edge. If the chopper speed goes up and RRPM slows down, there will come a point in the rotation when flow...
  13. GraviMan

    The Future of Rotorcraft

    Intermesher, I wasn't sure whether to start a new thread on this... I seem to remember you talking about maximum velocity of the Unicopter being potentially 500kts. The RRPM was to be designed to reduce, in order for these speeds to be achieved without compressibility effects on the blade tips...
  14. GraviMan

    main rotor blade failures

    Hmmm, it does seem rather odd. The only time related reasons i can think of are either corrosion or deterioration in UV light. I have never actually seen either affect aero components. The other possibility is that ten years ago Robinson introduced a modification to overcome the failure problem...
  15. GraviMan

    Waveguide

    Thanks GOTWW. So it's an exponential decay of the opposing currents. Just took me a while to gain intuitive understanding... Actually there are some nice demos in that applet, that nicely demonstrate the skin effect in lossy conductors. Thanks all for your patience. I have only limited...
  16. GraviMan

    Waveguide

    Sorry Biff44, perhaps I'm just being thick here... I spent 2 hours on the web looking for an explanation of why a plain sheet of copper should suffer the skin effect. Nothing. There were plenty of examples explaining how the induced current in a (solid) conductor forces the main current to the...
  17. GraviMan

    Waveguide

    Wowsers! Shameful to admit my brayne now aches too. I have read about the use of Schrodinger wave eqn to predict higher than normal ocean solitons. But, this is not quite what I was getting at... All I am interested in is using the full copper thickness of the waveguide. If the waveguide is...
  18. GraviMan

    Waveguide

    How does this change if the field is coming from both sides at the same time (ie constant electric field strength)? If a circular waveguide had a voltage directly injected into it would this help with the skin effect? The concept is that the voltage would induce a current in the outside...
  19. GraviMan

    New Rotorhub Invention

    "Increasing the engine's torque immediately increases the lift." Works fine as long as engine is producing torque. I was thinking along the lines of chopper puts itself into autorotative state (ie no height velocity curve, using same governing mech), but still allows pilot to pull RRPM off to...
  20. GraviMan

    Waveguide

    Thanks Biff44, for some really practical advise. I would imagine that there is not much point making the silver coating any deeper than the skin effect depth. Mart

Part and Inventory Search

Back
Top