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Thread: Fly Baby Made of aluminum like a Aerodrome WW-1 Replica?

  1. #1

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    Fly Baby Made of aluminum like a Aerodrome WW-1 Replica?

    I like the lines of a Fly Baby, but I also like the way the Aerodrome planes are made and ease of building. I was wondering if a Fly Baby could be made like the Aerodrome plane but maybe a little smaller like Ultralight size with about a 24' to 25' wingspan and about 16' or 17' long fuselage. And have a main wing USA27 airfoil for slow speed and high lift, and a 0009 airfoil on the tail feathers, to reduce drag and help a little with lift.

    Maybe use carbon fiber for the ribs, if not carbon fiber, aluminum.

    I read all of 'Building a Nieuport 11' by Frank Giger and like the way the Aerodrome planes are put together.

    Could the Airframe and wing be made like the Aerodrome Nieuport 11 plane but shaped like the Fly Baby?

    I checked out Ron Wanttaja's Fly Baby site and didn't see anything about an aluminum Fly Baby.

    Did anyone ever see or hear about an aluminum Flybaby?

    The engine will be a Kawasaki 440 for the ultralight version.

    Best regards,

    RonK

  2. #2
    rwanttaja's Avatar
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    It's much easier to design a biplane than a monoplane. Bracing the wings is a lot simpler when you have two panels with struts between them. The Fly Baby has a rather high percentage of wing failures, and casual modification is fraught with danger. Several of the Fly Baby cases were the result of the builder making a change that SHOULD have improved the wing structure, but had unintended consequences.

    I occasionally get emails along the lines of "I want to do **** to a Fly Baby, can you re-run Pete's calculations?" Whatever calculations Pete did on the Fly Baby were probably on a single page, and ended up in a landfill 60 years ago.

    With only one major supplier of spruce left, the Fly Baby community has been discussing alternate construction methods. Carlson Aircraft sells aluminum wing spars that could probably be used. However, this snowballs....a whole lot of changes come out of that apparently-simple choice. Metal ribs then seem logical, but how do they attach, how does one handle the cap strips, how does one build the false spar for the aileron, what substitutes for the top bevel on the spars, do you design the ribs with integral capstrips, what do you do for a wingtip, etc.

    It's not difficult to make the big decisions...metal C-section spar N x M in dimensions, ribs bent out of 0.020 2024, etc. But there's a lot of fine design detail on the stock wing that must be addressed, and it's tough to do that without intimate knowledge of how the stock wing is built. You can find details on the PB100 Companion Guide for the first EAA construction article:

    http://www.bowersflybaby.com/PB100/Guide_1.pdf

    Skimming through that might give you some indication of the subtleties of the wing design.

    The hard part is finding a modifier who will actually BUILD the wing and fly the aircraft. The hardest part is finding a modifier not only willing to build the modified wing and test it in flight, but also share the details with others.

    There has been less discussion about alternate fuselage designs, probably because the 3/4" square spruce used in the fuselage is easier to find that 3/4"x6" spar material.

    Ironically, of course, the Fly Baby stemmed from the Story Special... which has a steel tube fuselage.



    Ron Wanttaja

  3. #3
    robert l's Avatar
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    Of course I know absolutely nothing about design, calculations or strength of wood compaired to aluminum but I have built the wings and tail grooup for a Zenith CH-701. The spars are aluminum with lighting holes and an aluminum angle for a cap strip. It also has a doubler where the strut attaches. It's pretty simple and doesn't weight that much but how it compaires to a wood and fabric wing, I have no idea. I think someone designed a VP-I out of aluminum many years ago but I don't know any more than that. I guess I could have just kept my mouth shut !
    Bob

  4. #4

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    A nice true aluminum ultralight that WILL 'fly', baby.

    http://www.airdromeaeroplanes.com/Fo...4scale%7D.html

    lol

    Not what you may want but sure beats trying to re-invent the wheel.

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    Aluminum ribs should be lighter. But don't stand on the ribs like Pete did.

  6. #6
    rwanttaja's Avatar
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    Quote Originally Posted by Bill Berson View Post
    Aluminum ribs should be lighter.
    I dunno. 0.025" 2024 weighs about 0.36 pounds per square foot, just about the same as 1/8" plywood. The capstrips will add a bit of weight in comparison, of course. But scratch-building a plywood rib is easier than a metal one.

    Quote Originally Posted by Bill Berson View Post
    But don't stand on the ribs like Pete did.
    You HAVE to wonder how Pete got there. They had to have had a ladder or something next to the wing to let Pete climb up and (gingerly) step onto the wing. But did he come up from the trailing edge and step over the aileron (seems unlikely) or step off BACKWARDS from the leading edge (seems even less likely).


    The other thing I wonder is if the words "Hold", "My", and "Beer" preceding the taking of this photo....

    Ron Wanttaja

  7. #7

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    It could absolutely be done, particularly for the fuselage.

    The concern with the wings deformation in flight, which could be answered a couple ways by beefing up the compression struts and with the flying/landing wires. Certainly Robert solved that problem with his Eindecker...and it's actually a pretty big aircraft (the full scale one).

    The ribs in the Aerodrome design are just 1/4" tubing on the top and bottom, riveted into the back of the spars with a small gusset. Very light weight. The wings rely on the drag/anti-drag wires within to keep things tight. I spent more time on the jig (an hour) than I did actually putting them on the wing. Bending the tubing to the airfoil did take some time, but there's a big bunch of them.

    One would also have to improve the carry-throughs for the the wings, IMHO. This is the most common of the modifications to his plans, btw, with the little "blades" replaced by bit of steel tubing that fits neatly within the spars.

    A technique Robert used on the really big planes he designed, like the Sopwith Baby, was to have three aluminum tubes fill the main aluminum spar tube.

    [edit]

    A word on the "kits" Robert sells. Basically they're the plans and the material list, with the gussets pre-cut. Every tube is over sized, as one must cut, bend, and cope each one. It's pretty much the same as if one purchased just the plans and bought the materials one's self. I did the math on the costs of the materials if I bought them myself versus what Robert charges and it came out as pretty much a wash, with (depending on the vendor) Robert actually being a bit less expensive. He's got the power of wholesale working for him.
    Last edited by Frank Giger; 09-02-2018 at 10:12 AM.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  8. #8
    rwanttaja's Avatar
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    Quote Originally Posted by Frank Giger View Post
    It could absolutely be done, particularly for the fuselage.

    The concern with the wings deformation in flight, which could be answered a couple ways by beefing up the compression struts and with the flying/landing wires. Certainly Robert solved that problem with his Eindecker...and it's actually a pretty big aircraft (the full scale one).
    The problem isn't as much strength as the angle the flying wires attach to the wing.

    The lower the angle, the less effective the cable is in opposing flight loads....and the more tension in the bracing system. The Fly Baby is a low-wing airplane with the flying wires attached to the wheel hub. The Eindekker is a mid-wing airplane, with a more advantageous bracing angle. It requires a king post for the landing wires (the Fly Baby's attach at the upper longeron) but that's a cosmetic issue, not difficult to implement.

    The Fly Baby's fuselage sides are vertical, and, in fact, it would be relatively easy to do a mid-wing Fly Baby....

    This would greatly increase the effectiveness of the stock bracing system. The king post would actually be installed the same way as the cabane struts for the biplane version. The main drawback would needing to completely revamp the aileron control system, and adding the steps and handles so the pilot can get on top of the wing to get into the cockpit.

    Ron Wanttaja

  9. #9

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    Aeronca ribs are .020" 5052H-32, I think.

  10. #10
    rwanttaja's Avatar
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    Quote Originally Posted by Bill Berson View Post
    Aeronca ribs are .020" 5052H-32, I think.
    OK, the 1/8" plywood is about 0.35 lbs/ft^2, and 0.020 5052 is 0.28 lbs/ft^2. Each full rib on a Fly Baby is about 1.6 square feet (including nose, middle, and tail portions). There are 11 of these ribs on a single wing panel (however, some of them are smaller, but we'll count them all as full size). So the 11 1/8"wood ribs on a Fly Baby wing are about 6.25 pounds, and the same ribs with 0.020 5052 are about five pounds even. At this point, the wing panel is about a pound-and-a-quarter lighter.

    In addition, the cap strips on each rib are spruce (33 lbs per cubic foot) 1/2" x 1/4" by 55 inches long (approximate). That's 7 cubic inches per cap strip, another 1.5 pounds per wing panel. It's actually a bit less due to the slot.



    Stock wing panels weigh about 110 pounds, so the weight difference between wood and metal ribs is about six pounds for two. This assumes the metal ribs have a formed flange; if they have a separate cap-strip equivalent, the weight advantage will be diminished by the weight of the added flange and the rivets used to install them.

    Balance that, of course, with the ease of fabrication. Fly Baby's wood ribs are zipped out quickly using a bandsaw or router, and the capstrips are just a couple of cuts on the table saw. Scratch-building metal ribs is much more involved, especially if you want to form the flange as part of the rib itself.

    It's certainly not impossible, or even that uncommon...lots of RV-3s/4s, T-18s and Midget Mustangs were built. But it's far more time-consuming.

    Metal homebuilts really took off when kits with pre-formed components such as ribs became available. There are five times as many "kit-built" EAB RVs on the registry (RV-6, 7, 8, 9, 10) than pre-kit era (RV-3 & 4), and kits were actually available for these, as well.

    It's great...if you can afford it.

    Ron Wanttaja

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