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Posts posted by PerfManJ

  1. The prop slipstream has a large effect on wing lift, especially at low speeds. This is referred to as the "powered lift" portion of the total wing lift. The magnitude of powered lift is typically correlated to "thrust coefficient" (Ct). It all comes down the difference between the free-stream air velocity and the induced air velocity behind the props: the larger the difference (think high power and low speed), the larger the contribution of powered lift. In those conditions, the loss of an engine would cause a rolling tendency toward the dead engine.

    To get an idea of the powered lift present on the C-130, compare the normal and max effort takeoff speeds. Normal speeds are based on "power off" stall while the max effort speeds use the "power on" stall speed.

  2. I thought it was a good overview of the major differences between the mil and civil C-130J versions. As I recall from previous articles, the LM-100J is based on the stretched C-130J-30 since that was the basis of the original L382J civil cert in the 90's. Articles and press releases tend to use "C-130J Super Hercules" as an all-inclusive term for the "C-130J" family of aircraft unless they are referring to a particular variant or customer (USMC = KC-130J, USCG = HC-130J, etc.)

  3. FADEC = Full-Authority Digital Engine Control

    Basically a computer that controls engine operation based on input from the throttle quadrant. As polcat explained, there is a single "power lever" for each engine.

    Re-synching the props and reduced power takeoffs are also not required in the J.

    The J could still benefit from reduced power takeoff, in terms of engine life. Unfortunately, all of the takeoff performance data is based on max power only.

  4. Did the brakes hold while at 300 deg? Or did the heat dissipate quickly?

    That much heat will reduce the RTO capacity, but then again the carbon brakes have a much higher capacity than steel. It depends which energy limit they are using for RTO and max brake landing plans.

  5. The abbreviated USAF carbon brake test program used an E model...at Edwards (2300 ft MSL)...in the summer. So I don't think they ever even hit the T56 torque limit during the power-against-brakes tests. Wishful thinking that the brakes would hold on all C-130 models.

    How much heat is required to remain static with takeoff power? Could a few taxi stops add enough energy to prevent creep, without reducing RTO capacity?

  6. I found this while going through some of my LM stuff. It's a family tree of all the L382 versions up to 1986, including some serial numbers and differentiating details. Probably nothing new here, but I thought it might be of interest to the resident historians here. Good summary of the L382 lineage through the H model on one page.

    It's a copy of a copy of a copy and I'm not sure of the original source. There are no LM markings, but the bottom right corner says "PAGAN 11-20-86"

  7. There are rules of engagement.

    Why do they want to shoot you down?

    Are there snakes on the plane?

    Just tip the wings and follow the F-16’s to a friendly airport.

    Good point. Are the good guys in control of the plane? If the radios are out, rocking the wings is a sign of compliance with the interception by the F-16s.

  8. I think you're right. Or was it Executive Decision? I can't remember. But it's definitely been done.

    Thanks for joining in the conversation guys!

    I think it was Executive Decision. They used the fax machine in Air Force One.

    I like the safety valve. You'd have to climb all the way up on the ramp, but maybe instead of a flare, just use a flashlight or feed out a white flag. The F-16s might get the wrong message from a flare being shot in their direction.

  9. The JATO bottle supply is running out and none have been produced for quite a while. That's why Fat Albert stopped doing JATO takeoffs in 2009.

    I believe the LCs still use them when necessary on the snow, but they are seeking an alternative. On skis, sometimes they don't have enough power to accelerate up to takeoff speed so they need the extra thrust. In fact, that was the driver for testing the 8-bladed props (NP2000): The extra takeoff power would eliminate the need for JATO.


  10. Here's another briefing from Rolls-Royce with some high-level differences: http://www.lockheedmartin.com/content/dam/lockheed/data/aero/documents/global-sustainment/product-support/2012HOC-Presentations/Monday/Mon%201550%20Habersham-Rolls%20Royce-Roy%20Griffin.pdf

    AE2100D3 major improvements over T56:

    Two shaft (eliminates need for safety coupling and NTS system, allows speed optimization of individual turbine stages)

    Digital controls (FADEC, precise control and measurement)

    Higher pressure ratio (reduced fuel consumption and more power at higher density altitude)

    Reduced part count (maintenance and weight savings)

    Improved aerodynamic efficiency of turbine blades (reduced fuel consumption)

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