Move along - nothing to see here

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by drstress, May 27, 2019.

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  1. May 27, 2019 #1

    drstress

    drstress

    drstress

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    Bye

    There is an important omission in the calculations for the "Constraint Analysis". Put there on purpose to see what would happen. All of the calculations are simple "hand, closed-form" calculations any high school algebra student should easily follow. Since no one commented on any of them, I think either no one bothered to look through them or no one has the expertise to understand them.

    Either way this is my last post. I'm sure the "good ole' boy" club will pointlessly blabber on and on about any and all of my attempts to bring a small amount of order to what has to be the most random assortment of opinions I have ever experienced.

    Since I don't fit in to this culture, I will welcome it as a badge of honor to be exorcised from HBA.
     
    Last edited: Jun 20, 2019
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  2. May 27, 2019 #2

    pictsidhe

    pictsidhe

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    Well this makes a pleasant change, somebody designing an aircraft using engineering methods. The forum would benefit from seeing how you have gone about it. Perhaps you could start a member project blog and drown us in details.
     
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  3. May 27, 2019 #3

    pictsidhe

    pictsidhe

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    I'd say that I like your quotes, but that would violate rule 4 ;)
     
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  4. May 27, 2019 #4

    Vigilant1

    Vigilant1

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    Thanks for coming back, drstress. I was afraid we'd lost you.

    I'm looking forward to seeing your work.

    Will you be using constant speed props for this little bird? In the similar (but more modest) centerline thrust concepts we've most extensively discussed here lately (the "Beetlemaster" and the "Micromaster") we have generally assumed fixed-pitch props (for economy purposes and due to limitations on crankshafts and front bearings of the proposed engines--VW derivatives and small industrial engines, respectively). Controllable pitch props certainly reduce the tradeoffs required between acceptable single engine climb performance and two-engine cruise speed. But, Burt Rutan was able to get good single-engine performance and cruise performance with fixed-pich props on his Defiant, so it is possible.

    Thanks for letting us peer into the processes you've used.
     
    Last edited: May 27, 2019
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  5. May 27, 2019 #5

    pictsidhe

    pictsidhe

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    Looks good to me. I'll be investigating VSP. I'm just getting into checking stability for my own design.
     
  6. May 27, 2019 #6

    bmcj

    bmcj

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    One thing to keep in mind is that the dual verticals will likely lose a little bit of effectiveness due to interaction between the two inner surfaces. In other words, when yaw induces a lower pressure on one inner surface and a higher pressure on the opposite inner surface, there will be some cancelation of the two pressure fields as they try to equalize. That means that the stabilizing effect will probably fall in between that of a single rudder and two rudders each acting at 100% effectiveness.

    Of course, proper choices of distance and chord combinations can help mitigate some of the loss.

    Just don’t be surprised if two are not twice as effective as one at twice the size.
     
  7. May 27, 2019 #7

    Pops

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    I also thought of the Beetlemaster. If I had more time and energy I would like to built the Beetlemaster. Vigilant , I'm waiting for you to start construction.

    Looking forward for this thread. Hope is not to deep for this redneck . Already like the looks of it.
     
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  8. May 27, 2019 #8

    Vigilant1

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    These (rational) rules are going to get quite a workout. I might tape a cheat sheet to my monitor so I can tell who is being called out for what (me included). :)
     
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  9. May 27, 2019 #9

    Vigilant1

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    No, I'm just having a bit of fun. It will be good to keep the discussion as fact-based as possible, but that's a higher "standard of proof" than is normal here.

    It is hard to herd cats! Still, you've obviously put a lot of work into this, and it deserves a disciplined discussion. And if you've got analysis to go behind your design choices (single rudder or two, to cite a recent example), I'll learn a LOT from that.
     
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  10. May 27, 2019 #10

    Retiree

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    I look forward to the progress of your project. If you do not provide basic dimensions and performance targets, how can we judge what you are doing is reasonable?
    Doug
     
  11. May 27, 2019 #11

    imacfii

    imacfii

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    Why would you not want/like someone to share in your vision of creation? Is it a liability issue?
     
  12. May 27, 2019 #12

    Pops

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    Don't worry about me posting anything. You are on your own.
     
  13. May 28, 2019 #13

    BJC

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    I was going to post a comment, but I don’t meet your criteria.


    BJC
     
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  14. May 28, 2019 #14

    TFF

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    This is an Internet forum. We talk like best friends and fight like siblings at the same time. It’s no fun when someone’s work looks, well, like work. Well thought out is great but no one wants to read a term paper. Your credentials are pretty good but there are a lot of non engineers who have designed and built some mighty fine machines that are flying today, on this site. They can generally footnote their own work. They are equally as smart as any degree. There are also top engineering type too. As serious as we can be here, this is our fun time.
     
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  15. May 29, 2019 #15

    proppastie

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    So you will do structure analysis without detail design?
     
  16. May 29, 2019 #16

    wktaylor

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    Looks like a mini C336 SkyMaster**

    A few general questions.

    Anticipated design airspeeds: Green, Yellow, Red line/arc [VNE]?
    Design +G, -G load factors?
    Construction: metal, composite, hybrid?
    Tandem, side-by-side or staggered?
    Sticks or control-wheels?
    Gasoline or diesel engines

    NOTE.
    Twin V-Stabs/rudders and the boom-to-boom wide-span H-Stab/elevator can create some awkward/long control-cable/rod routing to ensure fully-coordinated-movement and non-asymmetric internal-loading and clearances... especially where the booms neck-down.

    Rear prop failures [blade or hub, makes no difference] can be catastrophic.

    Regards, Wil Taylor
    **I was lead USAF engineer for the O-2A/B (C337) for about 3-Years in the 1980s
     
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  17. May 29, 2019 #17

    wktaylor

    wktaylor

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    PS... Lighter-side : I, too, am a quotes-loving-guy... also... here are a few to consider from my files...

    A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. --Saint-Exupery

    At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation.” – Igor Sikorsky

    Simplicate and add more lightness.” –William B Stout, Early Aircraft Engineer

    The turtle only makes progress when its neck is stuck out." – often quoted by John Thorp

    A camel is a horse designed by committee." --Sir Alec Issigonis, British car designer


    Some fear flutter because they do not understand it. And some fear it because they do." --Theodore von Karman, aerodynamicist

    Any damned fool can criticize, but it takes a genius to design it in the first place." --Edgar Schmued, Chief Designer North American Aviation

    The Wright brothers’ design… allowed them to survive long enough to learn how to fly." --Michael Potts, spokesman, Beech Aircraft

    I would not trust the engine now. You have an engine by design, when it is running, it's trying to throw itself apart. Throw in a prop strike, and you have a built in problem that will show up when you are asking the most of the engine. A nice hot day at altitude just below gross weight. Then bam, you’re a glider. Or as one Boeing engineer put it, "have the glide characteristics of a streamlined man hole cover." That would be a bad day. --Eric Pfalzer T-18 owner after hearing of a second prop strike by another T-18.

    It has a Winchester 30-30 warranty … 30 feet or 30 seconds whichever comes first." --unknown

    MIL-TFD-J1T = Make It Like The F****ng Drawing Just 1 Time --unknown
     
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  18. May 29, 2019 #18

    proppastie

    proppastie

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    Error you can preview post under more options
    Posts did not get here
     
  19. May 31, 2019 #19

    don january

    don january

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    drstress. What a large amount of time spent on the web when you could have been building and sharing
     
  20. May 31, 2019 #20

    mcrae0104

    mcrae0104

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    What would you build if no one had taken the time to teach the designer of your airplane how to design an airplane?
     
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