Flying Boat or Bust

Discussion in 'Wood Construction' started by Heroben, Mar 11, 2012.

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  1. May 3, 2012 #21

    larr

    larr

    larr

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    Okay, let's Old Skool this:
    Given the era you're working with you should be looking at a ratio of 12 pounds of weight per square foot of wing area, so, in this
    case about 420 sq. ft. of wing area (which gives a take-off speed around 62 m.p.h.). For the wingspan of 33' you want you would need a chord of nearly 13' - a very high drag / poor performance proposition. You should consider a 60' wingspan and a 7' chord (or, if you need a shorter wingspan, a biplane layout something like a Felixstow.)
    I would suggest the RAF 34 airfoil (or the RAF 15 if you want something undercambered.)

    You're probably looking at a cruise speed of around 100 m.p.h., so your flying time is going to be 45 hours. With your specified fuel load you will need to achieve a consumption rate of no more than 10 g.p.h. - again, you need an efficient wing to achieve this.
    For this era, you're looking at designing around 13 lbs. per horsepower - 385 h.p. in this case. I don't know if the Ferrari engine is going to be usable - has any Ferrari engine ever run flat-out for 45 hours?

    Finally, I think you should reconsider an S.39 type design. The roomy enclosed cabin is a necessity for a flight of this length in Arctic conditions.
    Besides, your cat could move freely on it's way to the litter box.
     
  2. May 30, 2012 #22

    Heroben

    Heroben

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    DSC03655.jpg

    And what this may be? It is a throttle quadrant backplate, 1920's style. 4130, parkerized. Yehaw!
    Anything is possible, everything...achievable.
     
  3. Jun 1, 2012 #23

    Heroben

    Heroben

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    Heavy Metal.jpg Throttle Quadrant, still need to be drilled, deburred, engraved and a few other little touches. It's a labor of love AND patience.
     
  4. Jun 6, 2012 #24

    Detego

    Detego

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    [/TD]

    Flying Boat: Take-off and Land on Water, Ice or Snow; and if required Land. Plenty of room for Fuel & Supplies.

    2X Polaris,
    by
    karlgschneider
    on Oct 16, 2010

    [video=youtube;DiPzCgGpMIQ]http://www.youtube.com/watch?v=DiPzCgGpMIQ[/video]
     
    Last edited by a moderator: Mar 20, 2019
    Head in the clouds likes this.
  5. Jun 7, 2012 #25

    Heroben

    Heroben

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    Great model Detego, love the wing design and the way it's so close to the water ( almost an Ekranoplane) but since I'm alredy deep down to my ears on this design , I'll stick with it.
    For the bulkheads, I've decided to use a 3 layer composite.
    First layer is a 3 layer fir plywood ( yes DOUGLAS FIR, 20% more weight + added strenght), second is a solid layer of Baltek AL600 balsa core ( the same used on cigarette racers) and the third layer is again the 3 ply fir.

    Weight + strenght = flying boat.
    And Larr, max speed to be around 320kmh, I will reduce the fuel load and find a refuel in midroute. Will keep it small, currently looking for a 550 to 650hp powerplant.
     
  6. Jun 8, 2012 #26

    Heroben

    Heroben

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    I am building a MODEL. Yes, thats right. Im , again, building a cabin model, last time I've used cardboard and built it 1:10, this time I am using scrap wood and building it 1:1.( for angles testing and instruments placement, etc cab1.jpg cab2.jpg )total cab meassurements to be 156 cm, GO METRIC, and it's in compliance with faa minimum cabin requirements.
     
  7. Jun 15, 2012 #27

    larr

    larr

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    Okay, let's take a quick overview of some more old skool design considerations -

    Although you mentioned you were undecided on a particular airfoil, early designers simply used wing loading to size wings with the particulars of the airfoil shape for stall behaviour or drag considerations.
    In the case of simple wings the wing loading alone determines the stall speed of the aircraft - the higher the wing loading the higher the stall speed. Also, generally, the higher the wing loading the lower the drag so top speed goes up. So the trade off is between ease of take off and landing and cruise speed.

    So, for example:
    Supermarine S.4 - wing loading 24 lbs./sq. ft. stall speed approx 100 m.p.h. top speed 239 m.p.h. - 4.7 lbs./H.P. - 49.9 g.p.h.
    Supermarine S.5 - wing loading 28 lbs./sq. ft. stall speed approx 130 m.p.h. top speed 319 m.p.h. - 3.6 lbs./H.P. - 66.0 g.p.h.

    These kind of stall speeds would make landing these things on water a life altering event.

    In the case that you laid out, with a wingspan of 32.97' and a take off weight of 5000 lbs. any reasonable chord is going to put you into S.5 territory.
    I believe that is way too high, not only from the piloting aspect but also the structural demands.

    The next aspect is fuel consumption. Generally, aircraft engines consume around .44 lb. of fuel per horsepower per hour. So let's say to achieve your expected top speed of 200 m.p.h. your consumption would be 550 x .44/6 = 40.3 g.p.h. - so you would travel less than half the distance even on 450 gallons.
    Of course, at this point a top speed and actual fuel consumption are only vague guesses.

    Overall, I expect you want to make something like a smaller version of the CMASA Fiat MF.4 - but it's a fairly high drag design and you won't be able to meet your speed goal and have anything like reasonable fuel consumption.

    Italy-Fiat-MF4.gif
     
  8. Jul 4, 2012 #28

    larr

    larr

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    I was thinking about what you were trying to do when it dawned on me that overall your project was similar to the design goals of the Spirit of St. Louis. Here are some relevant pages from N.A.C.A. Technical Note 257:

    st louis naca-011 inv r.jpg st louis naca-012 inv r.jpg st louis naca-013 inv.jpg st louis naca-008 inv.jpg
    This should help you in sizing the wing and planning the flying speeds for maximum fuel efficiency.
     
    Last edited: Jul 4, 2012
  9. Aug 30, 2012 #29

    Heroben

    Heroben

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    Wow, long time no come here.

    Larr,

    You are the first one here to actually realize this.
    Yes, I am using some of the Spirit of St Louis data. And I did read the Tec Note # 257. Great document,yet very little on dihedral, swept angle, angle of attack and other important data.
    Now, if you could just think SAVOIA S.21 for a second...( Yup, it's red, it's rad and a pig's plane...)
    People just love the idea on facebook and deviantart.
    Anyways, working hard to raise the money to get the engine, its a Franklin XO-805Z ( and I still need 4 grand more, hehe)
    I really need to talk to you Larr, you've seen to be very knowledgeble. PM me.
    Also, considering seriously a 3 layer approach on the bulkheads, 3 ply FIR, baltek or another balsa core and another 3 ply FIR, T88 epoxy to hold it altogether.
    Throttle quadrant IS BUILT.
     
    Last edited: Aug 30, 2012
  10. Sep 14, 2012 #30

    Heroben

    Heroben

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    Scouting for wood. Called the guys at aircraft spruce, and it was a so-so. So if any oof you guys out here have scrap, uneeded wood, let me know, thank you all.
     
  11. Sep 14, 2012 #31

    PTAirco

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    Up in your corner of the country you ought to have access of a lot of good Douglas Fir. I'd scout around some local lumberyards and see what I could find. Years ago I bought Douglas Fir in 2"x6" x 12" chunks from a commercial yard. (After lots of searching, of course). There was not a single cubic inch of it that wasn't up to aircraft standards! One tenth the cost of "aircraft" Sitka spruce.
     
  12. Nov 1, 2012 #32

    Heroben

    Heroben

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    Thank you PTAirco, Any hints tips on how to choose?
    Heres a picture of the windshield frame. It came out of a PT22, pretty cool and red. Will start a proper log on the building log section. Any inputs/questions? Just PM me or post it right here on this page.. savoia_s_21_windshield.jpg
     
  13. Nov 3, 2012 #33

    Heroben

    Heroben

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    Started Design/build log.
     
  14. Nov 7, 2012 #34

    Heroben

    Heroben

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    Question of the day: Can I compute FROUDE number on a concave design?
    Asked it on the yesterday's Aopa webinar and got no answer. (Well, they're all CfI's and pilots there, not designers/engineers, after all) Does anyone here knows about it?
     
  15. Nov 12, 2012 #35
    Hello Heroben ..

    1) Great dreams achieved by great men ... so keep going regardless of all obstacles and difficulties.
    2) You sound so happy and in-joyfulness ... that is the ultimate goal of life .. keep it up .. yet reduce the Alcohol :) ..
    3) Old timers are great .. maybe not my first choice ... yet if they are your passion then they are your right and first choice ... just use them as a learning curve and not a denying factor of modern techniques and materials (Composite, Alum, etc.).
    4) Kindly post pix as they'll show progress and drive more contribution from everybody .. you already succeeded in involving knowledgeable guyz ...
    6) Best of luck .. and if you did not find an answer to a question .. use that to drive you in making research and experiments ..
     
  16. Mar 9, 2013 #36

    Heroben

    Heroben

    Heroben

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    Thanks Mylohaba, long time no come here, but project is going beautiful. I am currently LOFTING ( yup, weird to see a boat world word in here...) The keel, stem, knee and others. Also working on the instruments panel etc. Just google Savoia S.21 J and you will find a lot of drawings , pictures etc, Got even a FB page for it, lol.
     
  17. Mar 9, 2013 #37

    Heroben

    Heroben

    Heroben

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    Airfoil is a 24013.5
     
  18. Mar 12, 2013 #38

    larr

    larr

    larr

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    Happy 1 year anniversary for your thread!
    I don't think the Froude number will be of any use in wing design, although it should help you design a hull that performs well in choppy water. I don't think it's that useful in modeling flows in gasses.

    Thats quite an unknown airfoil you've picked. Any particular advantages?
     
  19. Mar 12, 2013 #39

    Lendo

    Lendo

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    Hello Heroben, Try looking at GA airfoils by Harry Riblett.
    George (down under)
     
  20. Mar 12, 2013 #40

    larr

    larr

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    Hmmm ... when crimson pigs fly?
    Die Flederschwein?
    I'm quite amazed at the cult following The Age of the Flying Boat has, even to highly detailed models of anime aircraft.
    None the less, you do seem determined to build a full size replica of a cartoon aircraft.
    Overall, I think you're extremely lucky that the model isn't completely bullocks.
    image3855.jpg
    In comparison with the Macchi M.33 the placement of the engine is comparable as is the general size and location of the control surfaces. The cabane and engine mounts are completely wrong, though.

    image3927.jpg
    The biggest issues are with the wings - the pontoon bracing is wrong, the chord is greater at the tips and the sweep is going to put the lift way behind the CG. If you are determined to make a cantilever wing you are going to need to do a much better job of engineering the wing than Macchi did on the M.33, and they had an easier planform to work with.
     

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