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Thread: Is it possible to make fast 4 seater out of wood ?

  1. #16
    Moderator autoreply's Avatar
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    Re: Is it possible to make fast 4 seater out of wood ?

    You're expanding your original statements:
    Quote Originally Posted by Vigilant1 View Post
    With a single engine out and 4 people aboard, no design capable of going "fast" could muster any type of climb.
    Quote Originally Posted by Vigilant1 View Post
    80 HP is not enough to generate safe climb rates in any conceivable aircraft that can also "go fast". I don't think it could even work with an aircraft designed to "go slow" (lots of wing area and camber). Packing the folks in tighter and streamlining the fuselage isn't going to make a significant difference in this problem (generating suitable climb).
    by quit a bit.

    The P2006T has demonstrated 100 fpm climb on one engine @ 7000 ft @ MTOW (single-engine ceiling) to the FAA. With 880 lbs of payload and a power output (according to Rotax) of 75HP and the high-altitude performance penalty, IŽd say you can easily do that on even less than 75 hp. Not to mention the Twin-R which is 750 (!) lbs lighter, aerodynamically cleaner and uses the exact same engines.


    Climb performance by the way is formulated in climb gradient, for various scenarioŽs. Page 1-B-7 and further:
    http://www.easa.eu.int/agency-measures/docs/certification-specifications/CS-23/CS-23 Amendment 2 (corrigendum).pdf

    (Far-23 is virtually identical)
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    Re: Is it possible to make fast 4 seater out of wood ?

    Dan

    I think the retracts do the speed for the Piel kite.

    TFF

    The eco-flyer LSA was 750 lbs empty with 100 hp engine...if you squeeze 50 lbs from that you get 700 lbs emptyweight and 4 persons ( 1 kid one adult ) 650 lbs this adds up 1350 lbs + fuel 75 lbs ( 4 hours ). This would also mean that one person flying it it would be 1000 lbs or less. With a lot better streamlining ala White Lightning I think 150 mph could be nudged in perfect circumstances...not in a snowfall etc. I think cowl, spinner, wingtips and wheel collars could be carbon...and fiberglassed interior of the wood and certain joints reinforced with it.

    Juke
    Last edited by topspeed100; November 4th, 2011 at 12:39 PM.

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    Re: Is it possible to make fast 4 seater out of wood ?

    Quote Originally Posted by autoreply View Post
    The P2006T has demonstrated 100 fpm climb on one engine @ 7000 ft @ MTOW (single-engine ceiling) to the FAA. With 880 lbs of payload and a power output (according to Rotax) of 75HP and the high-altitude performance penalty, IŽd say you can easily do that on even less than 75 hp. Not to mention the Twin-R which is 750 (!) lbs lighter, aerodynamically cleaner and uses the exact same engines.
    According to a Tecnam sponsored site(Tecnam Australia ), the P2006T is fitted with Rotax 912S engines that produce 100 HP. I think the correct number is 98 HP, but it ain't 80 HP or 75. With this power, at sea level and MTOW, it achieves a SE rate of climb of 380f/min. That's it. Tecnam claims the SE service ceiling is less than 6700' MSL (ref: same site as above), so they didn't bother to say what it's SE climb rate at 7000'MSL would be, I guess because they don't claim the aircraft is serviceable (SE) at that altitude.

    You are right, the Twin-R also uses Rotax 912ULS engines, and they still make 98-100 HP.

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    Re: Is it possible to make fast 4 seater out of wood ?

    80 hp Limbach Limbach-Flugmotoren.de - L 2000 EA

    AeroVee 2180 ccm and yet 80 hp too.

    Sonex -- The Sport Aircraft Reality Check!

  5. #20
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    Re: Is it possible to make fast 4 seater out of wood ?

    Quote Originally Posted by Vigilant1 View Post
    According to a Tecnam sponsored site(Tecnam Australia ), the P2006T is fitted with Rotax 912S engines that produce 100 HP. I think the correct number is 98 HP, but it ain't 80 HP or 75.
    It is 75HP at that altitude.
    You don't agree? So, if you go up to, say 7000 ft, your naturally aspirated engine still puts out 100% horsepower? I want that engine of yours desperately...
    Tecnam claims the SE service ceiling is less than 6700' MSL (ref: same site as above), so they didn't bother to say what it's SE climb rate at 7000'MSL would be, I guess because they don't claim the aircraft is serviceable (SE) at that altitude.
    The very DEFINITION of service ceiling is that 100 fpm (or more) climb at your service ceiling.


    We could argue endlessly about this. Simple FACT is that at least the P2006T has demonstrated the very things you initially claimed to be impossible ("With a single engine out and 4 people aboard, no design capable of going "fast" could muster any type of climb "), by the standards of both EASA and the FAA. For me, those standards are sufficient, so I'll just give up then I guess.

    Sorry if I sound irritated, but I've heard the "this can't be done" way too often. While a bit of conservatism and prudence to not be overly optimistic isn't a bad thing, I've heard way too often that something is "impossible" while it's already been done and flies just fine. Really folks, we can do better than Cessna did 70 years ago and you don't need 300 horsepower to lift a couple guys from the ground. Heck, I've flown (and taken off) with 28 HP on a 1650 lbs ship. Impossible...yeah, right...
    Last edited by autoreply; November 4th, 2011 at 01:29 PM.
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    Re: Is it possible to make fast 4 seater out of wood ?


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    Re: Is it possible to make fast 4 seater out of wood ?

    I'll let it go now.
    But with one last (ill-advised) comment: The Twin-R and Tecnam aren't made of wood.

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    Re: Is it possible to make fast 4 seater out of wood ?

    Seems that Rotax 912 ULS is 200 mm more narrow than a weaker VW based engine.

    How are they priced ?

    Rotax 912 ULS specifications, performance, weights and documentation

    I got roughly 11 000 € for the UL model ?
    Last edited by topspeed100; November 4th, 2011 at 02:49 PM.

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    Re: Is it possible to make fast 4 seater out of wood ?

    Twin-R seem to be only 450 kg empty ?...a twin.

    Then my 300 kg for single engine can be ok ?

    The diamond type seating means that it has single set of controls..is that a problem ?

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    Here is my previous dream with 2 x 50 hp engines; http://3.bp.blogspot.com/_1i7bx5vtc6...LINER_6_60.JPG

    Showing a 6 seater diamond seating arrangement.

  10. #25
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    Re: Is it possible to make fast 4 seater out of wood ?

    Quote Originally Posted by topspeed100 View Post
    How are they priced ?

    Rotax 912 ULS specifications, performance, weights and documentation

    I got roughly 11 000 € for the UL model ?
    The cheapest ones I've seen around were roughly 13K Euro's (including everything but the mount). The Jabiru (2200 or 3300) is an interesting and slightly cheaper competitor. Both the Dyn'Aero MCR4S and the Sling 4 are just over 300 kg (4 seats), so that's not too unrealistic, though I doubt you could reach that in a wooden construction.
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    Re: Is it possible to make fast 4 seater out of wood ?

    Quote Originally Posted by autoreply View Post
    The cheapest ones I've seen around were roughly 13K Euro's (including everything but the mount). The Jabiru (2200 or 3300) is an interesting and slightly cheaper competitor. Both the Dyn'Aero MCR4S and the Sling 4 are just over 300 kg (4 seats), so that's not too unrealistic, though I doubt you could reach that in a wooden construction.
    Sling is 380 kg D6 Sling Light Sport Aircraft - The Airplane Factory, Johannesburg, South Africa metal plane

    Dyn.Aero MRC4S seems to be glassfibre/carbon and 300 kg; dyn.aero

    The 912 ULS burns 1/3 more gas than a VW 80 hp engine.

    One thing one could do is to make it 4 seater size but still a single seater and have extra room for overniting and table and stuff...like golfbag and a surf board etc....? And make it 200 kg...and go for the FAI speed record ( publicity ) or any other record. Then after that make it to carry 4 people with heavier structure and bigger wing...right ?
    Last edited by topspeed100; November 4th, 2011 at 05:03 PM.

  12. #27
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    Re: Is it possible to make fast 4 seater out of wood ?

    Based on the P2006 specs on Wikipedia (2601 lbs and 250 fpm single engine), that's 20hp being used for climb... which means that 80hp is necessary for level flight at that (best climb, i.e. slow) airspeed.

    Interestingly, the quoted 1260 fpm with two engines means 99HP being used for climb, i.e. 101HP for level flight... meaning one number is wrong or they tested at different speeds.

    The single engine performance should be worse as a result of trim drag compensating the asymmetric thrust.

    -Dana

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    Re: Is it possible to make fast 4 seater out of wood ?

    Quote Originally Posted by Dana View Post
    Interestingly, the quoted 1260 fpm with two engines means 99HP being used for climb, i.e. 101HP for level flight... meaning one number is wrong or they tested at different speeds.
    You don't have 100% prop efficiency, hence the deviation. Based on their numbers, you use about 65-70HP for horizontal, sealevel SE flight, with all the trim drag and so on.


    @ Topspeed, I stand corrected for the Slings weight, though it was a lot lighter. Take note than those numbers are the 2-seater, they haven't presented the specifications of the 4-seater (though it has flown around the world)
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    Re: Is it possible to make fast 4 seater out of wood ?

    They seem pretty optimistic at the Tecknam twin specs, but it is true that most power on aeroplane is used at the take off..especially with a plane with retracts ( without collars ) that generate enermous drag and you also have the friction from the wheels to compensate as well...and acceleration in specified distance.
    Last edited by topspeed100; November 5th, 2011 at 03:51 AM.

  15. #30
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    Re: Is it possible to make fast 4 seater out of wood ?

    Quote Originally Posted by autoreply View Post
    You don't have 100% prop efficiency, hence the deviation. Based on their numbers, you use about 65-70HP for horizontal, sealevel SE flight, with all the trim drag and so on.
    Mmmm... yes. Serves me right for typing a technical reply on a Friday night after a few beers. If you figure 80% prop efficiency (rather good, actually) their numbers match up pretty close.

    -Dana

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