Question - Animations and Performance linkages
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  1. #1
    SOH-CM-2022 Mick's Avatar
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    Question - Animations and Performance linkages

    David asked me to post this question because he thought I might express it better. In fact, once I explain the situation I'll pose the question in his own words, which I cannot improve on.

    This has to do with our B-45 project. The B-45 was very sleek, much sleeker than it looks with its straight wings. The airframe produced so little drag that it caused problems.

    The B-45 had no spoilers or speed brakes. In the thin air at high altitudes there was so little dag that with all four engines at idle they still produced enough thrust to push the plane right up against its never exceed speed, and any attempt to lower the nose to descend would quickly result in overspeeding and the risk things like the wings coming off. At low altitudes there was a problem getting the plane slowed down to gear-down and pattern speeds.

    The test pilots at Edwards developed ways to work around these issues and they became standard operating procedures that all B-45 pilots were taught.

    At altitude, when it was time to descend they would open the main landing gear doors. Not drop the gear, just open the doors. The doors were edge-on to the slipstream so they experienced no significant air loads, but the drag of the open wells more than doubled the drag on the airframe and allowed the plane to descend without overspeeding.

    At low altitudes they would open the bomb bay doors, which would create enough drag to slow the plane to pattern speeds.

    David has managed to get the main gear doors to open without dropping the gear and linked them to the spoiler command, so B-45 pilots (at least those who read the Pilot's Notes section of the Manual) will know how to avoid getting stuck up there.

    We'd like to add drag to the open bomb bay doors too, to simulate the low altitude procedure. But...

    In David's words:

    "I have not been able to figure out a way to increase the drag when bomb doors are opened.

    To the best of my knowledge there are 4 controls that increase drag when activated: spoiler/speed brakes, gear and flaps, and thrust reversers which are not usable in flight). However all except the thrust reverser are already in use on the B-45 and can't be used for the bomb doors.

    I feel sure there must be a way to increase drag using an XML gauge or xml code in the makemdl.parts. But I don't know what it could be."

    Do any of you modelers have any suggestions?

    We could, of course, use the gear doors at low altitudes just as when up high, but we'd like to be able to do it the way real B-45 pilots did.

  2. #2
    The bomb bay doors are a lot like searching for that elusive "water rudder down/up" sound command.
    There isn't one.

    It seems to me that FS2004/2002 adds some drag to the landing gear in the .air file. Try to exploit that?
    I don't think you can assign drag values that are multi-stage (ie, gear partially down).

    Tagging the bay doors as spoilers sounds almost too easy but it may be the best way around the problem.
    You could try playing with the lift and drag numbers for the flaps, maybe give that first notch of flaps a higher drag value than the other positions?

  3. #3
    SOH-CM-2022 Mick's Avatar
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    Quote Originally Posted by Sbob View Post
    The bomb bay doors are a lot like searching for that elusive "water rudder down/up" sound command.
    There isn't one.

    It seems to me that FS2004/2002 adds some drag to the landing gear in the .air file. Try to exploit that?
    I don't think you can assign drag values that are multi-stage (ie, gear partially down).

    Tagging the bay doors as spoilers sounds almost too easy but it may be the best way around the problem.
    You could try playing with the lift and drag numbers for the flaps, maybe give that first notch of flaps a higher drag value than the other positions?
    Well, tagging the bomb bay doors as spoilers would work perfectly. The trouble is that only one animation can be tagged as spoilers and the main gear doors already are.

    In the sim, using the gear doors as spoilers at low altitudes as well as high would work, but that's not how it was done on the real plane and we'd like to have it work the same in the sim.

    I wonder if, in the real plane, using the gear doors in the thick air at low altitudes would subject them to more air loads than they could handle.

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