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  1. addaon

    A design I've been working on...

    Greetings. I'd like to present some ideas around a design that I've been working on, on and off, for a little over ten years now. I want to say, up front, that not a single piece of this aircraft currently exists -- some analysis has been done, but this is a pure paper design today. The design...
  2. addaon

    Checking in...

    It's been a long time. Real life has been intruding... but at least real life includes building flying things at this point! I've been working at Wisk.aero for the past two and a half years, and recently moved to Kanab, UT, so lots of life changes. Hoping to get back to some personal design...
  3. addaon

    Perl script for Riblett airfoil generation

    I've been working on a project that required generating Riblett airfoils again, and yet again I ended up writing a simple perl script to help. I've attached that script in case its useful to others; I'll probably update it occasionally, mostly to add more features for my own use. Be aware: All...
  4. addaon

    A lighter rivet gun?

    In building a design that uses exclusively blind rivets, I've learned two things about the $100 hydraulic rivet sold by Aircraft Spruce: it works amazingly well, and the ergonomic suck. My two complaints are that the weight of the hydraulic chamber at the bottom is quite awkward, and that my...
  5. addaon

    Aluminum thickness tolerance and structural calculations

    When calculating strength/stiffness, is it conventional to assume that all sheet metal is at the worst case thickness given the sheet tolerances (so 0.025" aluminum is treated as 0.0225", assuming 48" sheet width)? Or is there some fudge factor to account for most of the sheet not being at the...
  6. addaon

    Searching for a document

    "Control Power Criteria for Statically Unstable Aircraft". Looking for a digital copy, or a (university) library with a copy. Reluctant to drop $48 for a gov't printout without a better sense of contents.
  7. addaon

    Strake sizing

    Anyone have any documents about strake sizing? The concept is a bit late for NACA, unfortunately…
  8. addaon

    Propeller Challenge – Calling Jan Carlsson

    Jan, this is somewhat inspired by the "quiet props" thread, but also just a pragmatic question. The HKS 700T engine is an 80 hp turbocharged engine (77 hp continuous) that produces peak power at 5300 rpm (4900 rpm continuous), and has an integrated 2.62:1 redrive, for a prop speed of ~2025 rpm...
  9. addaon

    Sonex Onex – addaon – Bay Area, CA

    Greetings! Some of you may remember me from days of yore on this forum. Real life has been taking an uncomfortable amount of time, as it is wont to do. But on Tuesday, I will be taking possession of a brand new Sonex Onex kit. Doing it the lazy way, with the machined angle kit and pre-assembled...
  10. addaon

    Trailing edge construction

    This is a follow-up to a thread I posted earlier today, but I'd rather broaden the discussion and have folks chip in ideas. I'm trying to figure out how to build my trailing edges. What would you do? Given (tentatively): Trailing edge angle 16.8° Skin thickness (each) 0.020" Target bend...
  11. addaon

    Trailing edge construction -- riveting plastics and aluminum

    Folks, I'm trying to nail down the trailing edge construction for the elevons of my design. A folded trailing edge doesn't work for me, so it's going to be built up in some form. One option I was considering was RV-style, with a single rivet fastening the two skins and a wedge-shaped piece of...
  12. addaon

    Flap hinge position

    Does anyone have a source for aero data on the tradeoffs between a top-hinged and bottom-hinged simple flap? A NACA TR would be most excellent, and I'm sure there is one, I just can't stir it up. Obviously the bottom-hinged flap will be "better" in many ways (larger chord with downward...
  13. addaon

    Tractor Paramotor Trike

    Anyone thought this one through? Pros: Quieter (paramotor prop is in incredibly dirty air) Safe to run cageless (???) Easier to streamline Cons: Visibility Noisier for the pilot Can't use off-the-shelf paramotor Potential balance issues (can be designed around) What am I missing?
  14. addaon

    Crazy idea of the week - Scale Magister

    AMT Microturbines just came out with their new toy -- the Nike. At 176 lbs thrust, it's just begging to be used in a homebuilt of some kind. Sure, fuel consumption is beyond bad and well into ridiculous territory, but an hour of play time might be acceptable for a pure toy. A single Nike would...
  15. addaon

    Tip geometry for control surfaces with swept hingelines

    I'm trying to figure out how to handle the control surface tip geometry for surfaces with a slightly swept hinge line (<15°). It seems like there are two options: 1) Cut off the surface tip perpendicular to the spar. 2) Cut off the surface tip with a conical surface formed by revolving an...
  16. addaon

    Propeller effects on stability

    Can someone walk me through the propeller effects on stability? 1) I know there's a major destabilizing effect for a tractor, stabilizing for a pusher; is this due to the turning of the free stream air to align with the propeller axis with change in angle of attack? We've discussed numbers here...
  17. addaon

    The 140 hp gap

    So in evolving my design, I'm realizing that the ideal engine would generate between 140 and 150 hp at around 2700 rpm, and it would be nice to maintain that power until at least 10k feet. Also, weight is absolutely critical; and I'm restricting myself to aircraft engines. Currently I'm...
  18. addaon

    Riblett mean lines

    I couldn't find a thread on here about this already... don't recall if we've discussed it. Does anyone know how Riblett actually calculated his GA-x mean lines? The GA-4 and GA-6 seem to match their description of being a NACA a=0.5 mean line. For the GA-2 and GA-3, however, he added 0.3% and...
  19. addaon

    2090-T83

    Anybody gotten a chance to work with 2090-T83 or other production aluminum-lithium alloys? Any thoughts? 8% density reduction seems worth a good number of headaches in a lot of applications...
  20. addaon

    Paragliding

    Just got back from a week of flying in Valle de Bravo, Mexico. Thought I'd share a couple pictures.
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