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  1. davidjh

    Interference affects on Pitot probe

    Forget the trailing bomb instl; trust me, you do NOT want to get involved with those. Get a "kiel" pitot - it is a small device with a ringed shroud around the pitot probe inlet face. It provides 100% recovery over lage flow angles, but is not ice protected, but that is something you can handle...
  2. davidjh

    JET-A Density - Temperature relationship

    Shell used to give out a CD which discussed jet fuel in detail. Old memory is vague as to details in it tho.
  3. davidjh

    Operational reduction to flight envelope on loadsheets

    From my understanding there can be no "reduction" in the "approved" operational flight envelope for "revenue service" operations. The "approved" operational envelope is defined in the Aproved AFM, its apendices appropriate for that S/N'd airplane and the operators approved MEL. For a...
  4. davidjh

    Military Transport Aircraft

    Military transports often have very different, more severe fatique spectrums due to more frequent maneuvering (yanking and banking) than civil transports; often have design requirements for more maneuvering capability with system failures; and often have "survivablity" requirements (ie...
  5. davidjh

    Drag chute test

    Contact the chute manufacturers.
  6. davidjh

    Tangential Tension

    You need to create a "force balance" - the old F=ma - analysis. Almost all aero performance and S&C text books start with this. There are probably several sources on the net where you can get some reasonable drag force and lift force values for your aerofoils and (importantly) the drag force of...
  7. davidjh

    why aircraft weight has so big difference between landing and takeoff?

    To clarify a few things: the quoted maximum Takeoff Weight ("MTOW") and Maximum Landing Weight ("MLW") are structural design values - ie; the airplane meets all the type certification ("TC") (eg;FAR/JAR) structural design criteria/requirements. On any given takeoff or landing the MTOW and/or MLW...
  8. davidjh

    Help a student with aircraft SHM?

    Airborne sensors have improved dramatically in that last two decades. There are several, small, highly accurate 3-axis accelerometer modules available. I'd think that measuring "G's" at several places would be a good methodology to "infer" stresses. G's would also be a good measurment to use to...
  9. davidjh

    Calculating pressure altitude from geometric height

    If you are looking for "the" FAA Tech Center method I can't help - but there are good texts/papers available thru the internet (many by NASA) which describe the physics/geometry in great detail.
  10. davidjh

    Flow Conditioning In Tube

    Why not set up the airplane ducts in a lab in the physical layout they exist in the airplane with your measuring sensors; attach some "long straight" tubes with sensors to provide "truth" data and just obtain a calibration of the "as installed" ducting/sensor config. Since this is likely a...
  11. davidjh

    Max take off weight safety margins

    This vehicle was certified to US FAR Part 29. The FAA website can get you to the Type Certificate Data Sheet and to the Part 29 (ie; Amendment level) in effect at the time of certification. The individual P29 requirments can be thought of as defining a "minimum level of capability", but which...
  12. davidjh

    Under carridge dynamics

    There is a good book available thru AIAA
  13. davidjh

    Landing Distance Calculations with Reversers

    The answer is complicated. It varies with the "type certification basis" which the manufacturers work to. The operators have to honor the requirements in (the US) FAR part 121. Older airplanes had to demonstrate a "landing distance", on a dry smooth runway, with brakes only (no reverse), as part...
  14. davidjh

    Wing Placement and CG Location

    Wrongbrother; Experience says sooner or later in the vehicle's operational life there will be changes/additions that will shift the CG. So plan on a "CG range" within which you can meet basic stability criteria.
  15. davidjh

    Golf ball vs. race car

    Just a clarification on Cessna1's comments. The "VGs" seen on commercial jets are intended to impart higher energy air over the upper wing surface at the higher angles of attack (AOA) near/at stall. This is to either attain a slightly slower stall sped, or create acceptable handling qualities at...
  16. davidjh

    standard atmosphere

    Have just become aware of a NASA-HDBK-1001 which is a definition of the earth's environment. Do not know its precise content, but know it does talk to atmospheric temperatures, so appears to be relevant to your question.
  17. davidjh

    IAE V2500 pressure loss

    mordquest; I would say we need to think of two types of jet engines. The more recent designs have electronic control which keeps the engine at the appropriate (or selected) rating when the PLA is up in the "max power" portion of the quadrant. So as the airplane accelerates it will lower the...
  18. davidjh

    IAE V2500 pressure loss

    The equation you define is also used in some airplane design courses where the uninstalled thrust for each of the above mentioned ratings is needed/used depending on the flight regime/condition being analyzed. It appears to be from Jan Roskam's design course book. Your term "pressure loss" is...
  19. davidjh

    standard atmosphere

    The old P&W vest pocket handbook (mine - 1978 version)has such a chart. It defines a hot, tropical, cold and polar atmosphere each with their unique "non-standard" lapse rates. The handbook references a MIL-STD-210A.
  20. davidjh

    IAE V2500 pressure loss

    The "uninstalled thrust" - 23000lbs - is a "benchmark" value that has no real usefullnes in determining the installed thrust at any flight condition. And the thrust at any flight condition cannot be determined from an equation as simple as the one shown. There are several "ratings" (Takoff...

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