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Thread: Suggestion for overhead break and circuit procedure

  1. #1
    Join Date
    Aug 2009
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    131

    Suggestion for overhead break and circuit procedure

    I would like to propose a standard procedure for our overhead break and circuit, with reference to the B-25 pilot's manual I posted the other day.

    This is all open for discussion and agreement, but to kick things off here are my observations.

    Change to echelon
    Having nearly pranged whilst changing to echelon in a turn, I would like to suggest we only do this in level flight at steady speed. If we want to buzz the field for the benefit of the static camera, we can perhaps do this in vic formation then extend from the field, climb back to circuit altitude and change to echelon when lined up with the runway again.

    Turning in formation
    Turns are preferably performed away from the echelon. I think it is considered bad form by pilots to turn into your echelon.

    For vics, things are easier but we should set a minimum altitude of (say) 500 feet above terrain for a formation turn.

    Landing break
    If possible, echelon should be flying down an extension of the runway centre line in the upwind (landing) direction when the break is initiated. That way, aircraft can execute the same rate turn and end up on downwind parallel to the runway at the same crosswind separation. I would also like to suggest 10 to 20 seconds as the time between breaks, which gives us a more realistic (and less dangerous) separation between landing aircraft.

    Circuit altitude
    Circuit should be flown at a set height above the field. The pilot's manual says 800 to 1000 feet above terrain, although I should note that this is borderline for spotting the field over the instrument panel in-game, and if I fly a straight approach at this altitude I sometimes have to switch to the front gunner position to check my lineup.

    Circuit speed
    Pilot's manual says 150 to 170 mph, I think the higher end is better for controllability; 50% power and full pitch gives me this speed

    Circuit profile
    Circuits are a standard size, and this can be achieved by timing and standard rate turns. A rate 1 turn (approx 25 degree bank) is easy because it is marked on the bank indicator in the B-25. Length of downwind leg can be measured by a stopwatch or more conveniently by reference to ground reference points.

    Standard circuit is a rectangle with rounded edges, but I think we might get away with a race track style profile. I would welcome comments on this though. At Trapani, for example, an easy circuit profile is:

    1. fly heading 70 over field
    2. rate 1 turn to heading 250
    3. fly 250 until feet wet
    4. rate 1 turn to 70

    The standard rate turn at both ends guarantees you will be lined up on the field (absent any crosswind) when you complete the turn from downwind to final.

    Gear
    Gear is lowered at the end of the downwind leg, as per pilot's manual.

    Flaps
    One departure from reality, that I would really like to change, is maneuvering with landing flaps down. In reality, I believe only first setting (= Il2 combat flaps) is used on downwind leg, then second setting (Il2 takeoff) on base leg and third (Il2 landing) on finals and only when it is clear that you are going to make the field.

    Approach speed
    Approach speed is cut to 130mph when full flaps are down. This corresponds to a throttle setting of between 30% and 40%. In this configuration the aircraft will be in modified flight regime where throttle controls altitude and stick controls speed.

  2. #2
    Join Date
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    All great suggestions and some neat tips as well. Love the compromises and standardization of the turning procedure.

    We will attempt to do the overhead break by following these steps - this very Sunday.
    ... my foldable "Hog Pen"

  3. #3
    airdoc is offline Sergeant Major More Posts Than Postman Pat
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    great suggestions Steveiy.
    I 'd like to make comment on something : the speed at which the echelon arrives over the runway should be standardised, as you say, and this has an impact on the breaking time for each successive aircraft. Higher speeds will lead to greater separation. I think that 10 seconds may be a bit too much, but we could test it. Also, the speed at which the circuit is flown should not be very different in the different legs, because it will lead to different crosswind leg lengths. The bank angle is supposed to be standard for turns in a circuit, so that the lateral separation from the runway is the same during the first and second turn, but this assumes similar speeds. Generally, this means that we should pretty much fly at 150-170 mph when we are over the runway, start breaking while holding the same altitude (about 300m) and same speed, start lowering flaps (up to take-off) on downwind, and then make the final turn, after which gear down, full flaps down and speed bleeds while on final to 120 mph. If we are to hold 300 meters and 150 mph on the circuit, this means that the final turn should not be done abeam of the runway, but when the runway is at about 7-8 o clock (on a left circuit), otherwise we 'll be too high and too fast.
    Last edited by airdoc; 06-11-2013 at 15:39.

  4. #4
    Join Date
    Aug 2009
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    131
    Completely agree. I have been extending the downwind leg until (nearly) feet wet on the Trapani 070 approach, which gives me time to line up nicely, set flaps and bring it in for a greaser.

    Tonight I'll also try the "combat approach" described in the manual. That might be a better way to keep the strip in sight, but I'd rather have the planes making a set of perfect landings than some quick ones that might be more bumpy. Although I suppose we could argue that it is a combat situation...


  5. #5
    Join Date
    Aug 2009
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    I tried the combat approach. It works, but as expected there's a bit of weaving to line up, which doesn't look so tidy from the air.

    In terms of landing separation, it can be less when we have two strips like at Trapani, but between aircraft landing on the same runway I think we might need 20 to 30 seconds separation in order to avoid near misses on the ground. Also I think this is the minimum separation in RL due to effects like tip vortices which are not modelled in IL2. But anyway I think this will look great from the jeep if it is parked at the touchdown end of the strip.

    I've been trying to follow the manual and keep the nose wheel off the ground when touching down. Mine always bangs straight down anyway, doesn't seem to be much I can do about it. Anyone else find this?

    Also I am not cutting the throttle completely on landing as per manual, as I do not experience such a high degree of float. I am touching down at about 25% throttle.

  6. #6
    Tx_Tip is offline Captain More Posts Than Postman Pat
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    After running several landings suggest an altitude of 400m for pattern. Easier to pick up runway for final. Additionally I'm looking at a 17* bank turn required for the pattern. Nothing wrong with that mind you as we don't want to be over the beach during downwind. It does make a for a very aggressive turn to final into that "greased" landing though as well as staying in a tight formation within the pattern.
    Not having that problem with a two-point touch down. Probably not according to the manual but if I dirty up on my Final turn running at 150/mph or so with that extra 100m start on Final then drop throttle it makes it greasier.

  7. #7
    Join Date
    Aug 2009
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    Thanks Tip. We can try all these different techniques on Sunday and record tracks. Bumps and circuits day, anyone?

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