Pipistrel Panthera first flight

Discussion in 'Hangar Flying' started by autoreply, Apr 6, 2013.

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  1. Apr 6, 2013 #1

    autoreply

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    IMHO one of the more promising aircraft for the next decade, especially if they get the hybrid version off the ground.
     
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  2. Apr 7, 2013 #2

    henryk

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    =powerfull central bar=not symphatic to viewe...auter viewe=exellent!
     
  3. Apr 7, 2013 #3

    SVSUSteve

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    Other than the slight "sperm tail boom" look that is a likely hold over from their glider interests, it actually looks like a decent airplane. Never been a big fan of T-tails but it is nice to see something from Pipistrel that looks like something other than a weird little motor glider.
     
  4. Apr 7, 2013 #4

    autoreply

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    What's not to like about the necked-in tail? Less drag and less weight?
     
  5. Apr 7, 2013 #5

    autoreply

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    What's not to like about the necked-in tail? Less drag and less weight?
     
  6. Apr 7, 2013 #6

    bifft

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    It does look nice (tho I also am not a fan of the T-tail and thin boom just for looks, should work fine). What I wonder about is why they took two people up for the first flight. They did both have parachutes, but seems like risking an extra person to me.
     
  7. Apr 8, 2013 #7

    Nickathome

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    IMO, they need to dump the T-tail look, increase the size of the rear fuselage slightly. I think then it would look more like a high performance aircraft. Right now it looks like they took the front half of a high performance aircraft and mated it to the wimpy pencil fuse and T-Tail of the other three offerings they sell.
     
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  8. Apr 8, 2013 #8

    captarmour

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    Judging by the efficiency awards they continue to win I would say they are putting function ahead of form...a goooood thing...
     
  9. Apr 8, 2013 #9

    highspeed

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    +1 on Autoreply. The t-tail has lower drag and the necked down fuselage has less wetted area and is more efficient structurally. It's part of what gives the aircraft it's performance.
     
  10. Apr 8, 2013 #10

    Pops

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    But it looks like C***. Plus, I don't like T-tails.
     
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  11. Apr 8, 2013 #11

    captarmour

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    Forward view looks very restricted...too much of a good thing, maybe
     
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  12. Apr 8, 2013 #12

    ultralajt

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    I also dont find myself beeing confident of tiny apearance of the Panthera rear part of the tail, no matter how efficient that way it could be...

    In their world around flight, their plane (Sinus) suffer in-flight structural damage on the rear end of the fuselage. I hope they learn something from that:
     
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  13. Apr 8, 2013 #13

    captarmour

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    Thanks, that's serious!
     
  14. Apr 8, 2013 #14

    autoreply

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    An anecdotal report with a dozen possible explanations from an unrelated aircraft? Many aircraft suffer from damage to the tail due to rocks, idiots that remove balance weights resulting in flutter, hard landings, hangar doors and many other factors.

    With this certified design they must show the theory, ground-testing (shakers) and flight-testing to show it's free from flutter until over Vd and can take the ultimate (tail) load. That's a lot better than any Piper Cub or early Cessna has ever been through...

    I'm a bit surprised that many don't like the narrow tail and T-tail for it's looks. I thought it looked a lot better as all those fat-bottomed 70-year old ladies you see on a typical airport :)
     
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  15. Apr 8, 2013 #15

    harrisonaero

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    From a structural standpoint the highly necked aft fuselage isn't as efficient plus it creates more challenges for failure tolerance. Especially for a composite aircraft that can't be easily inspected for damage. The death of Martin Wezel from structural failure of the spindly E1000 tail comes to mind.

    So you're trading weight and robustness for a very slight drag reduction. Not that there's anything wrong with that- some folks like 'em skinny.
     
    Last edited: Apr 8, 2013
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  16. Apr 8, 2013 #16

    autoreply

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    It's lighter, not heavier in composites. We've just had a long discussion about that in another topic, but if you do the math it'll show that in composites a smaller diameter yields a lower weight, up to a certain limit obviously. Counter-intuitive, certainly, but composite tail design is driven by panel/skin buckling, not by bending moments (who are easily an order of magnitude lower than the smallest gauge of composite you can practically use) Metal thinking in a way I'm afraid ;)
    Another irrelevant anecdote. It is said it suffered catastrophic tail damage from a ground test. Whether you have a wooden, concrete or diamond plane, if you severely damage it on the ground, you shouldn't be surprised if it breaks seconds after take-off under a fraction of the limit load now, should you? That's why testing up to close to ultimate load and then flying it wasn't such a good idea in the first place.

    "damage tolerance"?
    We've only been flying, building, repairing and maintaining narrow, composite tail-boomed aircraft for 50 years. In those tens of thousands of certified aircraft and tens of millions of flight hours, I'm not aware of a single occurance of tail boom breakage, due to whatever cause, except for surpassing the operational limits. (In almost every case a severe ground-loop, diving past VNE, or full controls close to VNE)


    About time that the powered aircraft world gets beyond the 50's and moves (slowly I'm afraid) into the 21st century.


    *Autoreply starts running now* :gig:
     
  17. Apr 8, 2013 #17

    ultralajt

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    Not totaly unrelated aircraft. Sinus is Pipistrel design, and this "anecdotal" aeroplane was send around the globe by Pipistrel company, who design, build and prepare that plane for that adventure. Panthera was born in the same nest....

    I was just wanted to say (in may previous post) that I hope they design that tail stronger than it apears to my "naked eye" ! :nervous:

    I wish them all the best, but I am worried also....
     
  18. Apr 9, 2013 #18

    harrisonaero

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    Ok Auto, I'll bite.

    But sheesh, where do I start... I really don't have time for this. First off, let's get something straight: as far as human-carrying-flying-things are concerned, modern composite sailplanes aren't structurally efficient. They're aerodynamically efficient. Spindly fuselages and long skinny wings don't lend themselves to relatively lightweight structures. Neither does fiberglass. Relatively speaking of course.

    "Why are homely gals good kissers? Cause they have to be." Sailplanes bow to aerodynamics first and weight second.

    Now something like a Facetmobile- structurally efficient but not aerodynamically. Relatively speaking of course.

    So everything else is a compromise between the two. There's no free lunch. If you want good aerodynamics then sacrifice weight, if you want both light weight and good aerodynamics then plan to spend money on excellent materials and engineering ala Greg Cole.

    As far as how spindly you can go and still be efficient- how draggy do you want to be? The Panthera obviously has a sailplane lineage and likes the tadpole approach and is willing to pay some weight penalty.

    And the next time I hear someone say "metal thinking" I'm going to barf on my keyboard. Once the composite expert that spouts this actually has extensive experience engineering extremely efficient metal structures, then they'll figure out that there's more metallic materials engineering in composites than they care to admit. Until then they'll just throw weight at it with heavy fiberglass sandwich or hand laid up hotwired foam structures rather then knowing when to use metal structure thinking where appropriate. Hint- look at what the guys that are getting really light weight composite structures are doing... less and less foam and more local/tailored reinforcements... black aluminum... which they learned by first optimizing aluminum structures.

    Have to get back to work now... ironically taking a break from metallic materials to do foam and fiberglass design (not primary aircraft structure though- doh).
     
  19. Apr 9, 2013 #19

    rv6ejguy

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    Sailplanes and powered ones have different structural and aerodynamic concerns. When I watched the video, the first thing that struck me was the very clean design, kudos there. The second thing that struck me was the tiny tail surfaces. We'll see how that works out when they try expanding the C of G envelope and maintain adequate pitch authority and stability at low speeds. Trying to save that last bit of drag sometimes has tradeoffs. It didn't work well on some of the Lancair designs.

    I wish them the best, nice to see some new shapes emerging and some new choices in the market coming along.:)
     
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  20. Apr 9, 2013 #20

    deskpilot

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    I don't normally get involved with this type of discussion as I'm not that knowledgeable. However. At first glance, I agree with most of you. A very nice shape, slippery as hell and all that. On closer 'inspection' however. An all flying 'T' type tail plane. Hells bells, there's gonna be some stress not only in the hinge assembly, but also in that heavily waisted fuselage. Some one said that composite construction was lighter for this type of design but I reckon that to make it strong enough to take the loads it's also gonna have to be heavy enough as well. I'm sure the designer/s have looked at all aspects but............. Personally I'd have gone for a cruciform set up, all flying if necessary. At least that would give better stability to the horizontal stabilizer. Would it put it in the blanket zone though? maybe, maybe not.
    Have to admit I don't like that central bar in the windscreen either, but other than that, it's got possibilities.
     

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