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Thread: Aircraft design software

  1. #11
    steveinindy's Avatar
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    Quote Originally Posted by Mike Switzer View Post
    The math isn't hard, but if one doesn't have a good understanding of trig, vector mechanics, statics, mechanics of materials, etc it is pretty hard to know which formula to use. You need to know when to use Euler, when to use Johnson, or when to use something really obscure from Roark's book.
    ....or when to break down and buy lunch for (or give a good bottle of wine to) someone from the local engineering department. LOL
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  2. #12
    Mike Switzer's Avatar
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    Quote Originally Posted by steveinindy View Post
    You mean besides the fact that one has to be a bit masochistic to either enjoy FEA or to get a masters in ME?
    Yep. That combined with the equally masochistic tendency to enjoy higher math.

  3. #13
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    Quote Originally Posted by Mike Switzer View Post
    Yep. That combined with the equally masochistic tendency to enjoy higher math.
    I should introduce you to my soon-to-be father-in-law. He's a huge math geek. I've never seen someone so excited about his daughter having a boyfriend that can use "coefficient" in a debate.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  4. #14

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    Steal liberally from other designs!

    Fuselage design from a Champ, wing from a Cub, gear from a Husky (or whatever). Deviate slightly from them, but use them as templates.

    You'll learn plenty about design and structural loads as it is - but the materials and design work heavy lifting will have been done for you.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  5. #15
    steveinindy's Avatar
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    Quote Originally Posted by Frank Giger View Post
    Steal liberally from other designs!

    Fuselage design from a Champ, wing from a Cub, gear from a Husky (or whatever). Deviate slightly from them, but use them as templates.

    You'll learn plenty about design and structural loads as it is - but the materials and design work heavy lifting will have been done for you.
    The problem with "slight" deviations is that they can cause major shifts in load paths if the more or less ignorant would-be builder changes the wrong thing 'slightly'. You have to still do at very least a basic stress analysis make sure you're not going to pull the wings off your bird in a sharp turn or wind up with me helping to pick pieces of your skull out of the cowling after the plane folds up in a relatively low speed forced landing (I'm not being dramatic....I've had to help do this before). Similarly, I point you to the case of a guy who literally used an Aeronca for most of his build (how he got it approved as a "homebuilt" still baffles me). He failed to figure in the forces acting on a restraint attachment (it's not clear whether he installed it or if it was part of the original frame) which led to it failing and his smashing his face into the instrument panel. The aircraft was largely intact with only some relatively superficial damage but the pilot ended up dying.

    Contrary to popular belief, it's not the major oversights that kill most often when it comes to structural design. Usually, it's someone taking the "Eh, close enough" approach to things like seat attachments, harness tiedowns, etc. They may not be as dramatic as a wing separating in flight but they can turn a survivable crash into a fatal event. This happens very, very frequently especially with regards to seat attachment failures in GA aircraft.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  6. #16

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    I was thinking more in terms of rudder size and shape or using a push-pull control system versus a pull-pull type tinkering, or installing a rudder bar versus pedals.

    I've heard restraint harness horror stories, like the fellow who put in automobile seat belts!

    OTOH, I know of one homebuilt that was a "plane of many colors" where the guy pretty much borrowed the layout of the major components from other aircraft for his own. Naturally he had a LOT of knowlegeable people critique both the design and build, and made adjustments in the direction of safety.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  7. #17
    steveinindy's Avatar
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    I've heard restraint harness horror stories, like the fellow who put in automobile seat belts!
    Well if you look at the stuff in Aircraft Spruce that is rated for like 1500 lbs etc, those pretty much are automobile safety belts. That's probably the most common easily correctable single mistake homebuilders make when it comes to safety (besides exercising questionable ADM): underestimating the needed strength in restraint harnesses and seat attachments.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  8. #18

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    If you really want to be able to successfully use the types of programs you'll need to do this, you may want to consider taking some classes, that is unless you have the time to try to figure out all of the different functions and programs on your own. A class would at least teach you the basics, and you may even be interested enough to make a career out of it later on. Some of the best designers start out with an interest in a hobby like this one. If you need help finding a place to take these classes, check out my website to find the right school for you.

  9. #19
    Eric Witherspoon's Avatar
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    Quote Originally Posted by KDoersom View Post
    I would love to build a replica of the Piper Skycycle but as piper drawings were never drafted I am
    On my own to come up with the structure underneath the skin.
    You might want to contact Carlson Aircraft. They designed a replica of the PA-8 Sky Cycle for the homebuilt market in the mid 1990's. The company still exists, making aircraft components - spar extrusions, strut extrusions, wing ribs, etc. The replica was "appearance only", not an exact structural replica. Used fiberglass-covered steel tube fuselage, 2024 for the tail cone. I'm guessing fabric covering where appropriate (wing, tail, control surfaces) because the parts they make now are for fabric-covered designs.

    http://www.carlsonaircraft.com

    Let us know if they have any interest in providing parts and/or plans...
    Murphy's 13th: Every solution breeds new problems...

    http://www.spoonworld.com

  10. #20
    Kiwi ZK-CKE's Avatar
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    Quote Originally Posted by KDoersom View Post
    Guys thanks for all the great replies. I would love to build a replica of the Piper Skycycle but as piper drawings were never drafted I am
    On my own to come up with the structure underneath the skin.
    I'm thinking tube construction for the fuselage and tail feathers and aluminum for the wings.

    Al I have to go on are some 3 view drawings. I'll get a copy of that book and start reading. After I get something drawn up maybe someone could take a look at them for me. We are talking a pretty light and slow aircraft. Less than 700-800 pounds and less than 100 mph cruise.

    Thanks again

    Keith.
    With due respect, Piper didnt need flash Computer software to design it in the first place, so why do you need something now? Something at that end of the scale is quite suitable for "TLAR" methodology (That looks about right) and common sense - face it as far as structural loads go, on something that light, anything you build will be stronger than required. Aircraft design isnt a black art - I managed to do it and have a Beautifully performing aircraft. You will get bogged down in numbers, which at the end of the spectrum you are talking, are going to be exceeded by the margin of error anyway.... Just do it
    "If it was supposed to be easy, everybody would be doing it...."

    Proud designer / builder of Avian Adventurer ZK-CKE.

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