T-Tail Lance winglets and ????

Discussion in 'Avionics and Upgrades' started by Dan D, Nov 10, 2018 at 8:02 AM.

  1. Dan D

    Dan D Filing Flight Plan

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    Can anyone tell me about these add on winglets and the tail pieces in this photo?
    I have been thinking lately that there had to be a way of countering the the
    loss of airflow on the tail of my Lance at low speed. Until I saw this picture I had no idea that there was anything out there. Searching the web has given me nothing about these.
    They work on jets, why not on the lance?
    Any help would be appreciated.

    Dan Lance winglets.jpg
     
  2. Checkout_my_Six

    Checkout_my_Six Final Approach

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    The winglets are for cruise efficiency....not low speed performance. Same for the strakes on the tail.

    The winglets typically are used to transform the wing tip vorticies, the drag created from the air flowing into the low pressure regions, to transform the drag to lift, by effectively increasing the wing span. It's a small percentage and arguably not easily measurable for our low speed aircraft.

    The tail strakes are used to keep flow attached and guide stream lines, like a dart. Unless the Lance has ductch roll issues, which I didn't think it had that, I'm not sure what they were going after with that mod.
     
  3. Tantalum

    Tantalum Pattern Altitude

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    I cannot remember where I read this, but at some point I had read that the strakes on the Lear Jets help at high angles of attack and slow speed to put some additional pitch-down force at the tail and reduce stall tendencies

    Found it!
    https://forums.jetcareers.com/threads/learjet-design-question.78183/page-2

    The last post on that page I linked above is from a pilot who tested it in real life

    I would be curious what, if any, effect though it would have on a Piper Lance
     
  4. Kenny Phillips

    Kenny Phillips Line Up and Wait

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    The strakes are usually to assist when elevator effectiveness is reduced by blanking at high angles of attack. At least, I believe that's the purpose on Lear jets.
     
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  5. hindsight2020

    hindsight2020 En-Route

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    Nope, the other way around. Ventral strakes don't help with elevator pitch authority. Fixed surfaces in the empenagge with any anhedral help with directional stability when the vertical stablizer is blanketed by the fuselage. The presence of said fixed surfaces actually lessens pitch authority, by forcing the nose down in high alpha situations. this is done in order to facilitate stall recovery, but work against the positive pitch authority of the aircraft, especially one already aerodynamically compromised as that stupid Piper T-tail in their piston line up.

    These are needed in the Lear to not need a stick pusher for certification. In a T-tail Lance the problem is lack of pitch control authority, so the nose drops on its own when you blanket the tail anyways, making strakes pointless on that affair. The real aggregate effect those have during landing on a Lance, is that you will hit the elevator stop at a lower aircraft pitch attitude due to the negative pitch moment of the fixed strakes, an attitude lower than tail blanketing, and the aircraft will touchdown pancaked compared to the stock T-tail setup. It's basically training wheels for pilots that can't land the t-lance fast enough to not break the nose gear upon tail blanketing. Now, if those things were movable, then yes that would fix the problem. But, at that point we call that a conventional tail so wtf is the point of keeping all that extra weight and hardware in the vertical stab!....LOL

    What would help you in this make and model would be canards, not strakes.

    BL, You have to fly that thing faster on touchdown, there's not getting around it the fact they put the stab in the wrong place. It's not the end of the world but it's a comprised design decision done for cosmetics, and it was ultimately a failure, on both fronts to add insult to injury. Problem is I haven't seen a discount on them compared to straight tails to consider buying one these days.
     
  6. Unit74

    Unit74 En-Route

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    Spent all that on looks and still has the fishbowl cowl.....what a friggin imbecile.
     
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  7. tspear

    tspear Pattern Altitude

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    Actually you have that backwards. Winglets, properly designed, are most effective at high angles of attack. e.g. slow flight, climbing... At lower angles of attack (e.g. fast cruise) they can actually increase drag.

    Tim
     
  8. nauga

    nauga Pattern Altitude

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    Winglets are typically added for cruise efficiency - why else would gliders have them? ;) Ventrals are typically added for low-speed directional stability or (with 'anhedral') to some extent nose-down pitching moment at the expense of nose-up. They don't increase elevator effectiveness.

    Nauga,
    stability derived
     
    Last edited: Nov 10, 2018 at 8:21 PM
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  9. tspear

    tspear Pattern Altitude

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    Because gliders generally fly at max L/D which is a higher angle of attack. Piston aircraft rarely fly at max L/D.

    Tim

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  10. nauga

    nauga Pattern Altitude

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    Rarely? Max range for a piston airplane is at L/Dmax. Also consider winglets on large transports. They're point-designed to maximize efficiency in cruise, where the airplane spends ~95% of it's time.

    Nauga,
    with minimum drag
     
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  11. tspear

    tspear Pattern Altitude

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    Go back and read what I said. You are making a spurious point and going in circles.

    Tim

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  12. nauga

    nauga Pattern Altitude

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    Winglets are typically added to decrease drag by tailoring lift distribution, and they are typically point-designed to decrease drag at a specific condition - usually cruise. That specific condition can even be (and typically is for larger airplanes) 'fast cruise', like, say, 0.85 to 0.87M.

    If I wanted to go in circles I'd be at max endurance, not max range :D

    Nauga,
    done.
     
  13. tspear

    tspear Pattern Altitude

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    And nothing you said disagrees with my statements.

    Tim

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  14. Tarheelpilot

    Tarheelpilot En-Route

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    Perhaps I misread your post. Didn’t you proffer the idea that winglets often increased drag at high cruise? I’ll never say never but every aircraft I have ever flown that had winglets were designed to reduce drag at normal cruise speeds above max l/d. They were specifically engineered to save fuel at normal high speed cruise. Not so much for low speed environment.
     
  15. tspear

    tspear Pattern Altitude

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    I said for example(e.g.) I never stated an absolute.
    Winglets reduce wing tip vortexes and reduce drag. Wingtips vortexes are the greatest at high angles of attack where the pressure differential above and below the wing is greatest.

    Most airlines although going fast in absolute terms actually fly fairly close to L/D. If they did not, the accountants would be all over the pilots for "wasting" fuel.

    And yes, the winglets are tuned, and are a compromise. Depends on the customer and the manufacturer to determine how the compromise is done.

    Tim



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  16. Checkout_my_Six

    Checkout_my_Six Final Approach

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    I guess that's why we see lots of STOL aircraft with winglets.....o_O
     
    Last edited: Nov 11, 2018 at 11:36 AM
  17. luvflyin

    luvflyin Final Approach

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    It sure does look like the could not do anything to elevator effectiveness. I can’t see anyway they could alter the flow of air over the elevators, actually the stabilator I think it is on a Lance. But it sure looks like they could substitute for a lack of stabilator effectiveness at high angles of attack.
     
  18. tonycondon

    tonycondon Gastons CRO (Chief Dinner Reservation Officer)

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    Gliders have winglets because all of the racing classes, except for open, are span limited. Winglets allow a slight increase in efficiency, if properly tuned, without an increase in span.

    Gliders, at least on XC flights and competition, almost never fly at Max L/D.

    Winglets on a Lance seems like lipstick on a pig to me.
     
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  19. Tarheelpilot

    Tarheelpilot En-Route

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    Ok