\\\ New plane///

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by TES111, Oct 18, 2003.

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  1. Oct 18, 2003 #1

    TES111

    TES111

    TES111

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    I have recently started building a scaled model of a canard pusher. I have the CG, Wing Incidences & Wing areas worked out. The Plane has flown without power a couple of times now. I was wondering how to go about scaling up the design so that I could start building a full scale version of this new X-Plane. How does the scaled wing area need to change in order to not be to big and act more as a sail in the air? Is there a practical book / computer program for the non engineer to start doing the calculations for spar strength, wing area and thrust to weight ratios for my plane? I have a gibillion technical questions such as skin thickness, spar strength, air foil. I want her to fly fast and long. Kinda like the Berkut but a 4 to 6 seater. Attached are some pics of the model when I was working out the CG location. I am currently working on the fuselage and will post pics soon.

    Thanks in Advance

    TES111
     
  2. Oct 18, 2003 #2

    TES111

    TES111

    TES111

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    Hers Johnny!
     

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  3. Oct 18, 2003 #3

    TES111

    TES111

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    Johnny 2
     

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  4. Oct 18, 2003 #4

    TES111

    TES111

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    Johnny 3
     

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  5. Oct 18, 2003 #5

    orion

    orion

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    In general, there is no direct correlation between a scaled model and the full sized craft. When smaller models are used in a verification exercise, the information gained is usually qualatative, not quantitative. You can get general behaviour characteristics such as how the aircraft behaves in a stall, how CG affects flight trim, etc., but you cannot get any actual figures such as perfomance, effects of wing loading, etc.

    Furthermore, due to the effects of the Reynold's Number (scaling effects), it is highly likely that the sizing of the wings and the airfoil sections you selected for the model, will not be applicable to the larger craft.

    True, models are used in the aerospace industry however the small aircraft are designed to provide very specific information and require very specific methods of construction, weight distribution and of course, power. The process actually needs to start with the design of a full scale craft, which is then reduced in size for the tests. The process does not really work the other way around, for the very reasons you mentioned in your text. Scaled up, the wings tend to be too big, the airfoils are all wrong and the power density level of a model airplane tends to be much higher than what we see in larger aircraft.

    Models are of course also used in wind-tunnels however, a good set of model runs may run you in the tens of thousands of dollars, and then you have to know what to do with the data. Here a correlation can be made but you have to start with a pretty optimized design before you shell out the money for construction of the tunnel model, and for the subsequent runs.

    The questions you ask are of course the basic requirements for the development of any airplane. To cover all the bases however, the subject matter covers hundreds of engineering hours, even for an experienced designer. This is well beyond the capabilities of this medium - in other words, you have a lot of work ahead of you or you will need to get professional help.

    There are of course many texts out there for the amateur, although most responsible authors will point out that without the necessary background and experience, any amateur attempting to do all the design work himself will most likely overlook something and get into trouble. Furthermore, even the most basic texts will require some amount of technical and mathematical knowlege of the reader in order for the amateur designer to understand the process at even the most basic level.

    Can it be done without an engineering degree and experience in aircraft design? Possibly. However, in the same breath I must point out that the past several decades are full of examples where folks have tried this, with less than successful results. Many of them, sadly, are no longer with us.

    The decision process for you will therefore be a balance between the level of comfort you have in your ability to cover all the bases by yourself, the time involved in actually getting the background and doing the work, and the cost of having it done right by someone who is capable and experienced in the field. I will point out however, that in the case of the latter, while you may get someone to look over your shoulder as you do this, most professionals will be hesitant about doing this type of work piecemeal as this puts the responsibility of your work on them.

    Additionally, going through all the steps yourself, including getting all the applicable background information, will take a significant amount of time (possibly many years). Are your therefore committed to the process for that period of time? If history is any teacher, the trend is that most people eventually get discouraged and the projects fall by the wayside. The work may be revisited again and again over many decades, but as is the case for most of this type of development, other issues may take presedence and in the long run, it eventually fades away.

    I know this sounds somewhat discouraging, but I've been in this industry now for well over twenty years and pretty much have seen most of the hiccups encountered in amateur aircraft design and construction. I'd love to see more innovative design project get past the drawingboard, as I'm sure would many of us, but time and funding tend often to be underestimated, leading to the aforementioned discouragement and program end.

    If you would like to discuss this in person, I can try to steer you in a direction that may provide you with a better chance of success. You can get my contact information at my company's web site at www.oriontechnologies.net. Good luck.

    Bill H.
    Orion Technologies
     
  6. Oct 20, 2003 #6

    StRaNgEdAyS

    StRaNgEdAyS

    StRaNgEdAyS

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    design tools.

    Hey there.
    Here is a link to a great application that I have found made my work a LOT easier.
    It's called AirplanePDQ
    While you are there check out their other stuff.
    It has an inbuilt CAD program (intelliCAD I believe) and it features a deisg wizard where you input any key requirements you may have and it does the inital calculations for you.
    You can modify your plane quite extensively, and test it's capabilities before it even gets to the workshop.
    Computers are such wonderful things, years ago they would have killed at least a dozen test pilots to achieve what this beauty little app does in a couple of hours..
    I have attached a *ahem* "patch" to help use it as well...
    :whistle:
     

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  7. Oct 20, 2003 #7

    orion

    orion

    orion

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    Software such as the aforementioned AirplanePDQ package have come a long way from the early attempts at providing amateur designers with tools to make the conceptual effort at configuring an airplane easier. It must however be pointed out that the software can only get you in the ballpark.

    Within the past two or three years there have been at least four attempts to develop new aircraft using solely the information gained through the use of these simplified design packages. All four were failures.

    Any tool is only as good as the person using it. A tool that is "simplified" in order for a wider variety of individuals to be able to use it will of course have further limitiations.

    Now, don't get me wrong. The work done by the developer (Gil Crouse)
    should be recognised and commended as it is probably the best work to date at developing this type of analysis. But by making the design process more automatic and understandable by the layman, the developer necessarily had to take a number of shortcuts. Solely depending in this software could lead any amateur designer down the wrong path with a false sense of confidence.
     
  8. Oct 20, 2003 #8

    TES111

    TES111

    TES111

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    Agreed.

    This software gave me a completely different set of numbers for a well known design. I have to chalk this up to a bad tool for design use. I have to say that this software may give you an Idea of where to begin with a 1/4 scale model but it will not give you a well mannered aircraft. There are to many variables left out of the soup. It gave me a gross weight that was way outta range for the fore mentioned plane.

    Just my 2 cents

    TES111
     
  9. Oct 20, 2003 #9

    StRaNgEdAyS

    StRaNgEdAyS

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    Yes I totally agree with you Orion,
    these applications are there to be used as a too to assist in the design process, not replace it completely.
    After all, where would the challenge be for us mere mortals if it was all just a case of push a button and out spits the exact thing we want?
    They are great applications, and this one is the easiest to use that I have come across so far, and the level of information and the degree of customisation, is very a helpful aid indeed, but as you say...
    It's not by any means a stand alone tool.
    It has however save me a great deal of time, as I have drawn up and scrapped quite a few plans using this tool, in so much less time than I have doing it the hard way...:roll:... because it does pretty well let you know if it is a viable option of not, in a very short time.
    I have a couple of options now with which to explore, and it certainly has made the process of a full scratch build much easier. especially since I am working on a 100%experimental craft, right down to the engines.

    :D
     
  10. Oct 20, 2003 #10

    TES111

    TES111

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    Post some pics or post your web site Strange. I would love a little inspiration.
     
  11. Oct 21, 2003 #11

    StRaNgEdAyS

    StRaNgEdAyS

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    Sure thing...
    I'm hunting for vector conversion plugins so I can upload a couple of pics...
    :D
     
  12. Oct 21, 2003 #12

    StRaNgEdAyS

    StRaNgEdAyS

    StRaNgEdAyS

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    pics

    ****!
    I didnt think it would be a hard ask to find a plugin for photoshop to let it read vector format!
    :mad:
    I did end up finding a shareware app to convert them to jpegs so I can post them here for you...
    This is the current evolution of the craft I am designing...
    It is constantly undergoing revision but for now this is how it is...
     

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  13. Oct 21, 2003 #13

    StRaNgEdAyS

    StRaNgEdAyS

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    and another

    :D
     

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