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Thread: New guy with some questions

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    New guy with some questions

    Id like to say hello, and how great of a forum this is, ive been reading seems like none stop for several days now. I don't have a kit or plans, just some ideas of what id like to learn an aircraft gets built our not.
    Id like to make an aircraft 103 legal with a closed canopy (theiss speedster style) i noticed that entire plane was made of white bead board styrofoam, other then some wood structure... I have read all the posts i could find about solid core wings and the type of foam to use.. I still am unsure if the white bead board could be an option. I understand it will require the use of epoxy and not vinylester... I am asking because i have almost unlimited supply of large foam sheets..they have a taper, 3" down to 2"... 7 1/2 feet long and 4 feet wide. I was thinking of a bi wing construction, because shorter wing lengths could be used... I did some backwoods testing (me and my buddy jumping on the foam supported only on the very edges) found that a span of this foam 7' by 2' could support us (330 pounds) that is the bare foam.i might have figured this wrong, but that would be about 23.5 lbs per sq. Foot.... I don't know the first thing about aircraft design, just what i think makes sense... If anyone could once again shed some light on this subject that would be of great help... Oh and when i said almost unlimited supply..... I get more sheets then i can store (some has become insulation)

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    Registered User cluttonfred's Avatar
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    Re: New guy with some questions

    Quote Originally Posted by Deuce View Post
    Id like to say hello, and how great of a forum this is, ive been reading seems like none stop for several days now. I don't have a kit or plans, just some ideas of what id like to learn an aircraft gets built our not.
    Id like to make an aircraft 103 legal with a closed canopy (theiss speedster style) i noticed that entire plane was made of white bead board styrofoam, other then some wood structure... I have read all the posts i could find about solid core wings and the type of foam to use.. I still am unsure if the white bead board could be an option. I understand it will require the use of epoxy and not vinylester... I am asking because i have almost unlimited supply of large foam sheets..they have a taper, 3" down to 2"... 7 1/2 feet long and 4 feet wide. I was thinking of a bi wing construction, because shorter wing lengths could be used... I did some backwoods testing (me and my buddy jumping on the foam supported only on the very edges) found that a span of this foam 7' by 2' could support us (330 pounds) that is the bare foam.i might have figured this wrong, but that would be about 23.5 lbs per sq. Foot.... I don't know the first thing about aircraft design, just what i think makes sense... If anyone could once again shed some light on this subject that would be of great help... Oh and when i said almost unlimited supply..... I get more sheets then i can store (some has become insulation)
    Welcome to the group. As far as using foam as a structural component, there is foam and there is foam, and it's important to know exactly what kind you are using. Two resources that I can suggest are:

    1) the thread on the Robin ultralight design on this group -- Robin Ultralight -- and the related blog pages including the history of the Wren ultralight;

    2) I would also recommend buying a set of Sky Pup plans, which might work for you a design, which could be modified to have a fully enclosed cockpit, or would be a good way to learn about wood and foam construction -- Skypup Plans

    Cheers,

    Matthew
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    Re: New guy with some questions

    Deuce, welcome!

    White bead board is not often used for aircraft construction due to its very low structural strength. It is sometimes used as a filler or as a shaped support for the actual wooden structure as it appears on the Theiss, but the blue foam is much more common. Even within the same type of foam, there are different densities, which affects the strength.

    Your test of jumping on an edge supported board doesn't really mean much from a standpoint of aircraft design, since it doesn't represent a typical aircraft structure configuration. Nor is your figure of 23.5 lbs/ft² meaningful; what you describe is bending stress, where the strength is a function of the thickness of the material as well as the flat area.

    You might be able to safely use the white bead board for some things, like wing or tail ribs, or fuselage fairings, but the actual amount you'd use would be relatively small and you wont' save much money by using the bead board on hand, so you're better off using a higher grade material.

    -Dana

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    Re: New guy with some questions

    Quote Originally Posted by Dana View Post
    Deuce, welcome!

    White bead board is not often used for aircraft construction due to its very low structural strength. It is sometimes used as a filler or as a shaped support for the actual wooden structure as it appears on the Theiss, but the blue foam is much more common. Even within the same type of foam, there are different densities, which affects the strength.

    Your test of jumping on an edge supported board doesn't really mean much from a standpoint of aircraft design, since it doesn't represent a typical aircraft structure configuration. Nor is your figure of 23.5 lbs/ft² meaningful; what you describe is bending stress, where the strength is a function of the thickness of the material as well as the flat area.

    You might be able to safely use the white bead board for some things, like wing or tail ribs, or fuselage fairings, but the actual amount you'd use would be relatively small and you wont' save much money by using the bead board on hand, so you're better off using a higher grade material.
    As Dana said, welcome to the forum.

    There are so many better options out there that resorting to the "cheapest" or most readily available often winds up costing you more in the long run. In many cases- even in commercially built aircraft- selecting the wrong material for the wrong application for structural purposes can cost you your life. Sadly, this is more common in experimental amateur-built (E-AB) aircraft because some see the leeway that the FAA gives us as an excuse or encouragement to try to use any material they have access to try to build an aircraft. You see people using non-standard bolts to anchor vital parts of the structure (seats, restraints, etc) and other things that, in hindsight, are very poor choices when they should be learning from those who did the same thing previously and had a "bad outcome".

    If you don't mind me getting on the soapbox I used for my EAA Experimenter article for just a second, you're going to use that leeway, it should be move the field forward and not trying to simply prove you can make a very simple aircraft out of marginal materials. That has been repeatedly done before with mixed results. Why not pick a bigger challenge and make a real mark for yourself in the annals of aviation history and have some fun while doing it?
    "Unfortunately in science what you believe is irrelevant."- Orion

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    Re: New guy with some questions

    Thank you guys for the replies.... Like i said im here to learn al i can, i hate to see things get thrown away but don't hate it enough to danabet My life on it... I was looking as another option, to make the structure out of .059 4130 tubing and them use the foam as.a filler as Dana stated.... Forgive my spelling and typos i use my phone for the internet....

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    Re: New guy with some questions

    to make the structure out of .059 4130 tubing
    If you're going for an ultralight, that might be a little too heavy if you are going to provide a decent frame. Aluminum would be another option if designed properly. Perhaps going for an LSA might be a better option which would give you a similar amount of freedom in operations but more weight with which to work?

    Forgive my spelling and typos i use my phone for the internet....
    No worries, especially if you forgive my being blunt most of the time. LOL
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    Re: New guy with some questions

    I like when people don't beat around the bush... I have a tgood but of experience welding aluminum, my Masson concern would be the HAZ in thin wall tubing or annealing it to 0 temper. I welded a few small test pieces .025 thick with some .060 alum. Sheetmetal for gussets.... I no nothing about rivets, or other forms of tube construction... I was thinking 4130 for the fact i would not have to worry ever about the welded

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    Re: New guy with some questions

    Quote Originally Posted by Deuce View Post
    I was thinking of a bi wing construction, because shorter wing lengths could be used.
    An other, often unnoted advantage of biplanes/quadplanes etc is that wing volume is much lower.
    With a biplane you double the span, but chord and wing thickness are halved, so a net reduction of wing volume of 50%. That allows you to either have only half the foams weight, or use a higher-density foam (stronger) for the same weight.

    Triplanes or quadplanes result in 3 and 4 times reduction in volume...
    Aude somniare

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    Re: New guy with some questions

    An other, often unnoted advantage of biplanes/quadplanes etc is that wing volume is much lower.
    That depends on whether you need that wing volume for things like fuel storage which probably played a role in the disappearance of the biplane. However, if you're not looking to do more than putter around on sunny days and never get far from the pattern it wouldn't be as much of a problem.
    "Unfortunately in science what you believe is irrelevant."- Orion

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    Re: New guy with some questions

    In your OP you stated(i noticed that entire plane was made of white bead board styrofoam, other then some wood structure... ) What plane were you looking at? I think this would help answer your question better.

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    Re: New guy with some questions

    I was looking at the theiss speedster.. They no longer sell the kit, or the plans that i know of.... It seems like a cool little craft

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    Re: New guy with some questions

    i believe herb beaujon used solid white foam in his flybike wings, with wood spars.

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    Re: New guy with some questions

    Quote Originally Posted by Deuce View Post
    I was looking at the theiss speedster.. They no longer sell the kit, or the plans that i know of.... It seems like a cool little craft
    Sorry for not noticing the obvious. All the designs I know that use foam don't fall under the 103 rule because of weight.If you have your heart set on a enclosed cockpit try looking at mini max and the high max,these are wood construction.
    If your looking to get in the air faster try going to barnestormers.com and checking out the ultralight section there.You can pick up a MX quicksilver for next to nothing and it is a safe and proven design.Hope this helps you out some.

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    Re: New guy with some questions

    Quote Originally Posted by Deuce View Post
    I like when people don't beat around the bush... I have a tgood but of experience welding aluminum, my Masson concern would be the HAZ in thin wall tubing or annealing it to 0 temper. I welded a few small test pieces .025 thick with some .060 alum. Sheetmetal for gussets.... I no nothing about rivets, or other forms of tube construction... I was thinking 4130 for the fact i would not have to worry ever about the welded
    Welded aluminum is rarely used for aircraft construction, partly because it destroys the temper, as you mention above. Aluminum tube with bolted or riveted gussets is a very common way of building an ultralight. Welded 4130 (.059 would be way too heavy,though) also produces an extremely strong structure, but ultralights that use steel usually only have a central cage and motor mount of 4130, with aluminum for the tail and wing structure.

    -Dana

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    Re: New guy with some questions

    Thank you guys for your replies... It may be years before i start... I keep a note book of this stuff ... You guys are awesome. I really like the computers run on smoke tag.. Ha ha

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