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Thread: The differences flying a Tricycle grear and Tractor

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    PRA Secretary JOHN ROUNTREE 41449's Avatar
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    The differences flying a Tricycle grear and Tractor

    See this link on PRA.org's website to read all the information even more than is posted here:
    http://pra.org/default.aspx?p=TriGear2Tractor&i=83

    I email Ron Heron (The Little Wing designer) asking the question I asked Vance basically what is the difference transitioning from being trained in a tricycle gear to a Little wing = tractor.

    I basically fingered it out from observation looking at the blade angle of attack just sitting with tail wheel down but wanted to be sure. Ron's reply made it certain I do understand the difference and provided procedures:
    --- Start Reply ---

    John,

    Rotor management is different because the "fuselage deck-angle" of the rotor is different when the aircraft sits 'tail-down' (compared to a tri-gear pusher which sits level).

    In other words, the rotor has a positive angle to the inflow, even with the stick forward. With the stick neutral, you have a rotor angle of ~18 degrees.....the same as when a Bensen tilts back onto its tailwheel. With the stick full-aft, you have ~ 9 degrees more positive angle than is possible in a tri-gear.

    This allows very aggressive take-off and landing performance....but the management is critical. It is very easy to get into blade 'flap' if you don't fully understand how the autorotative rotor works. For example, you might be just fine pulling the stick full aft in a tri-gear pusher as you try to accelerate the blades. However, in the LW, it already sits at a 9-degree angle... so a neutral stick is the same as full-aft in a tri-gear pusher. If you pull the stick full aft before the rotor is 'ready' in the LW you will be guaranteed to get blade flap...and it may well whack the tail.

    Once you get a mental visualization of all this, it starts to make sense and you can see how you can take advantage of the situation rather than let it cause you grief.

    Using the forward stick lock is a must in the LW for ground maneuvering. It is very important as this will minimize the likelihood of inadvertent blade flap and it keeps the rotor at a maximum distance from the tail. By the way, this was standard procedure for all direct-control Autogiros from the 1930's and '40's. Using the rotor brake properly is important as well, since the rotor angle can't be reduced to zero (because the aircraft sits at ~ 9-degrees positive). In a wind, this can be problematic when trying to slow the rotor after landing.

    It is almost a 'non-issue' once you have the concept down. I have never whacked a tail in all the years I have flown. But, it is because I have followed procedure for the aircraft configuration.

    Good to hear from you John. Let me know if all this makes sense.

    Ron

    ***********************************
    Little Wing Autogyros, Inc.
    Mayflower, AR USA
    www.littlewingautogyro.com

    --- End reply ----

    PS: The stick lock keeps the stick to full forward for those who are not familiar with the Little Wing.

    =====
    The primary concern during spin-up is the same as any gyro....do what you need to do to build blade rpm without flapping the blades. The KEY thing to watch is to ease the throttle up until your inflow accelerates the blades to a 200 rpm minimum (you can supplement the process with the prerotator as needed....just remember to turn it off!). At this point, you should feel noticeable drag and further advancement of the throttle will begin to extend the main landing gear shock struts. When the struts begin to extend, you are ready to power-up. Adjust your stick position fore/aft as required to maintain extended struts and at the same time, allow the aircraft to accelerate to take-off speed. (Generally, this will be slightly aft of neutral.)
    Once you have 200 rpm and the struts start to extend, the rest is easy...just power up and keep the aircraft straight. It will lift off three-point.

    On landing, just level off with the mains just clear of the runway and ease off the throttle and then ease back the stick. It will touch down three-point. Bring the stick full-back to stop, then, ease stick to neutral and once the rotor rpm dies off, ease stick into the stick-lock.

    It almost "self-lands"....even if you accidentally touch the mains first..just get off the throttle and pull the stick back. Don't use the brakes at all...you won't need them until you begin to taxi. The extra 9 degrees of deck angle allows a very aggressive rotor angle for stopping via rotor drag. Just remember to put the stick into the lock before taxi.

    You can practice over and over to get the rotor speed technique down before committing to take off. Get used to the procedure required to obtain 200 rpm without blade flap. Then, add more power and watch the struts begin to extend. Play with stick position and find the 'sweet spot' where the rotor drag is not excessive and the aircraft will accelerate as you add throttle. Then, pull the power off, ease the stick back and get a feel for the stopping aspect. Get into the habit of using the stick-lock when the time is right.

    Once you get all this down pat, you will only have to continue adding power after the struts start to extend and you will soon find yourself in the air. Just remember, it IS a taildragger and directional control is critical. Never let it swerve hard.

    Take-off Procedure

    Stick lock engaged.
    Taxi into position and hold brakes on lined up on the center line.
    Release stick lock and hold stick full forward then start pre-rotator (It is helpful to have the rotor turning slightly before engaging the electric prerotator since it is pretty brutal from a dead start. That being said, I have done it many times at Oshkosh since they don't allow anyone near the aircraft when you get ready to spin-up)
    When pre-rotator’s up to speed ease stick back to approximately neutral.) release brakes then turn off pre-rotator.
    Apply throttle the setting will depend upon wind. Normally, ease the throttle open gradually and accelerate as required to induce an increase in rotor rpm. Note: You can turn the prerotator on as required to keep blade speed from dying down until the inflow from movement takes over.
    As the blades come up to speed (200 min.) ease stick farther back and add throttle until the shock struts begin to extend. NOTE: You never want the tail to lift.
    Add full power and position stick as required to allow aircraft to accelerate to take off speed. NOTE: The shock struts should extend fully and the aircraft should lift off three-point. If the tail tries to lift, your stick position is too far forward.....just ease it back.
    As she begins to lift off maintain full power and lower the nose to straight and level gaining airspeed then begin your climb.
    Fly her like any other gyro after that.


    Landing Procedures

    Normal landing approach
    When just above the runway reduce power from approach speed. Level off and then ease stick back in order to touch down three-point. Reduce throttle to idle, ease stick full back to stop the aircraft. Once firmly planted, ease stick back to neutral until rotor speed diminishes and then place stick into the forward lock.
    The tail wheel should touch at the same time as mains. Never move stick full forward during the landing....only after the aircraft has stopped or nearly so.
    Engage the stick lock only after you have bled off the landing flare rpm. The aircraft should be stopped or nearly so.
    Apply rotor brake.
    If you have a head wind taxi off runway and position LW so you have a tail wind and finish stopping the blades with the rotor brake.
    Taxi back to hangar


    Ron
    ***********************************
    Little Wing Autogyros, Inc.
    Mayflower, AR
    USA
    www.littlewingautogyro.com
    Last edited by JOHN ROUNTREE 41449; 11-21-2016 at 09:44 AM.
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