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  1. rtfm

    Why round tubes for landing gear?

    Hi, I'm sure there is a perfectly obvious reason all landing gear are constructed from round tubing, but I don't know what it is. Anyone care to enlighten me? Likewise for wing struts. Duncan
  2. rtfm

    Tailwheel config question

    Hi, I am assuming that the further aft the CG is from the main gear, the more difficult it will be to keep a tail dragger tracking straight down the runway, and vice-versa. Are there guidelines for this? Raymer suggests an angle of from 16 deg to 25 deg from the main gear to the CG. My...
  3. rtfm

    The "Skyflow" cedar strip Flea

    Hi, I've been stuck at home during lockdown here in Brisbane, and with no wood to keep me occupied in the Yardshed, I've been spending my hours designing a cedar strip single (and double) seat Flea. These are very much in the concept stage, with very little by way of actual design having taken...
  4. rtfm

    Composite aircraft engine cover material?

    Hi, I guess the title puts my question quite well. Regards, Duncan
  5. rtfm

    Centre of lift in a swept wing?

    Hi, In a rectangular wing, finding the chord-wise centre of lift is simply a matter of finding the 25% position of the chord. However, in a swept wing, is it as simple as finding the 25% position of the MAC? Duncan
  6. rtfm

    Spruce for wing struts?

    Hi, All planes use either steel or aluminum for wing struts. So my question is, what is wrong with spruce? Just a relatively small cross section is sufficient for spars, so why not use a significantly larger cross section of this material for wing struts? Just askin' Duncan
  7. rtfm

    Junkers ailerons - size?

    Hi guys, Does anyone know the optimum size for Junkers ailerons? Is bigger more powerful? One would think so, but there has to be a point at which size, drag, weight, effectiveness etc intersect. What is usual? Duncan
  8. rtfm

    Small streamlined tube?

    Hi, I was looking over a Pitts Special a while back, and noticed that some wires stiffening the wings were actually very small streamlined tubes no bigger than a half inch long. Well, more like solid metal shaped like two ovals. I've looked for anything similar to this, but can't find...
  9. rtfm

    Vortex generators on laminar flow airfoils

    I was browsing the web this morning, and chanced upon vortex generators. After following several links, I came across a technical paper which stated: That seems awfully far forward, but I guess on a turbulent airfoil that makes sense. But what about a laminar airfoil? The NACA737A415 (for...
  10. rtfm

    The JK-2 Nano

    Hi guys, Have you seen this one? The JK-2 Nano. Beautiful little thing. Almost makes me want to have one. The only real thing that bothers me is the high thrust line. From the manufacturer's FAQ: Can you tell me why I shouldn’t be concerned about the high thrust line? We have done in...
  11. rtfm

    NACA 747A315 coordinates?

    Hi, I have the DAT file for the NACA 747A315 airfoil, but it is pretty ordinary, truth be told. In particular, the LE consists of 3 points only. Just terrible. Does anyone have a coordinate file for this airfoil which is actually usable? I also went hunting for how to generate the airfoil -...
  12. rtfm

    The AFB (Amazing FleaBike)

    Hi, I've been quiet on this forum for some time, but now that production of the FleaBike has begun, it's probably time to start a thread, and post some photos. Originally inspired by Fritz' "Ranger" concept, I decided to put mouse to computer screen and produce my own sit-on Flying Flea. This...
  13. rtfm

    Anniversary of Orion's death yesterday

    Hi, As many long-time members on this forum will remember, Orion (Bill Husa) was one of the forum's brightest lights. Extremely knowledgeable, generous with his wisdom, yet extremely patient with newbies. My wife used to say that if Orion said it was OK, I could fly my design, otherwise, no...
  14. rtfm

    Another Flying Flea question

    Hi, I have been corresponding with a Flea afficianado here in QLD Australia. He lives about 2 hours from me, but so far, we haven't met. However, he has strongly criticised my contention that a Flea should have (at most) -1 deg negative pitch, and a max of +12 deg. Most Fleas for which I have...
  15. rtfm

    How much to tighten bolts?

    Hi, A quick question - how much pressure is required to adequately tighten a bolt through Spruce? Recommendations re: washers to spread the load - required? Regards, Duncan
  16. rtfm

    A question for all Flying Flea aficionados

    Hi, My question relates to where along the chord of the front wing to attach the pivot. Some background: In the plans, the front spar is used to anchor the wing pivots (this is eminently sensible since this is the only solid place in the wing). From the plans, the front spar is situated 260mm...
  17. rtfm

    Control linkages geometry

    Hi, I'm hoping someone on the forum can help me with something I just can't figure out... I'm trying to work out how to implement control linkages which need to go round corners. Something like this... Surely there is a well-defined way to arrange the links to accomplish the above? I'm...
  18. rtfm

    Calculating additional lift from deploying flaps

    Hi, I'm sure Raymer covers this in his books (I have both - however I can't follow the math in his big book, and my home-builders version is out on loan). So can anyone help me out? I'm trying to calculate the amount of additional lift per degree if possible, provided by the deployment of...
  19. rtfm

    Junkers flaps with folding wings

    Hi, I'm struggling to figure out how to activate Junkers flaps in a folding wing scenario. With fixed wings, one would just hav e a continuous linkage to the flap itself. But how does one activate the flaps when the wing (or the outer panel of the wing where the flaps live) is either removable...
  20. rtfm

    Anniversary of Mark Stull's death

    Mark Stull - Innovator, intrepid builder, experimenter, and an inspiration to us all. Died today on the maiden flight of his new design. RIP Mark...