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Thread: Cedar strip airplane

  1. #36
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    Default Re: Cedar strip airplane

    Quote Originally Posted by kjl38 View Post
    Hi rtfm

    Am I correct in assuming the wood is non structural and just acts as a fairing with a frame that takes the stresses?

    There is a guy in NSW by the name of Allan Newhouse who builds very nice strip plank kayaks, he posts on woodworkforums as anewhouse https://www.woodworkforums.com/searc...rchid=36748364

    He was very approachable when I met him at the Hobart wooden boat festival and I think he would be an excellent person to contact for Australian advice.
    Excellent lead. Thank you.

  2. #37
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    Default Re: Cedar strip airplane

    Quote Originally Posted by DeanP View Post
    If the cedar strips are only a "core" material, you could save a lot of weight by going to balsa. End grain balsa is the traditional wood core material. (Think of the DeHavilland Mosquito bomber. Wood inner and outer skins with an end-grain balsa core.) If you are relying on the strips for structure beyond core properties, I would think you would need some strips off the longitudinal axis. I built and fly an (aluminum) plan and am building a cold molded sailboat (cedar strips with +/- 45 degree cedar veneers). I've always wanted to build a wood plane, but have not found a design just right for me. Good luck.

    Dean
    Hi Dean,
    The *main* reason for using WRD planking is the aesthetics. I have plenty of high density foam, but the plane would end up having to be painted, defeating the purpose.

    As far as longitudinal structural members (longerons) my design has three:
    Side view with bulkheads.jpg
    These tie together the bulkheads.

    I understand the softness of WRC, but it is a beautiful substitute for the foam I already have in the Yardworks.

    Duncan

  3. #38
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    Default Re: Cedar strip airplane

    Quote Originally Posted by upchurchmr View Post
    Speaking as a structural designer for military aerospace, I'd be scared to death of watching this thing take it's first flight.
    Not sure why. There are a hundred design features which I haven
    't mentioned, because this is a forum for wooden boats, and that's all I was asking about. But I'll answer your specific questions.
    You haven't talked about how to get the loads from the front wing to the pod, and then the reaction loads from the rear "wing" via attachments to the pod.
    The front wing is attached via a swivel directly to one of the forward bulkheads. The outer panel of the wing is attached via two struts attached directly to bulkheads. All bulkheads are tied together by three longerons. The picture below shows the bulkheads (in red) and the longerons (in brown).

    Can you show the wing connection?
    Here is a picture of the HM293. The front wing is attached to the fuselage by two 2mm steel brackets bolted to the main frame members. The rear wing is fixed and bolted on (again, to the main longeron). Mine is very similar, except my wings are attached to longerons and bulkheads.
    HM293 basic side view.jpg


    The very first thing you need to do is make samples of strip planked skins with the different materials you think you could use and break them to see which is strongest.
    Second it to compare your tests to strength requirements at different places in the pod.
    Why? I already know T88 is stronger than the wood.
    Third is to build something strip planked. So you have some idea of the actual techniques required to get the curvature on that thing.
    This is a good point.
    I strongly suggest you paint this thing. You won't believe how much easier and quicker it is to build for paint.
    Probably, but this defeats the whole purpose.

    please do a final sandbag load test when the plane is finished.
    I do plan to do this.

    To answer your questions.
    Staples or nails to position strips for gluing. The weight of a clamp can twist a strip out of position, unless you have very unusual clamps
    Many people have said the opposite. To be expected, I guess. I think I'm going to use staples with a protective piece of plywood to protect the WRC when I pull the staples out.

    No way to tell if you need multiple layers of strips until you show us the joint you are making.
    No multiple layers. On layer only. Why would I need more? 6mm is plenty as a layer between the glassfibre.
    You don't need a "keel" unless there is a specific high load you need to accomidate.
    I will be using a keel, a mid-longeron and an upper longeron. These will tie the bulkheads together. I'm not envisaging the cedar planks providing anything structural.
    How are you going to hold the shape formers (bulkheads) so that they are aligned? The ones that will be removed. Typically they should be about 1' apart to get a smooth exterior, without a lot of fairing compound.
    Formers and former stands.jpg

    As you can see, 14 formers, attached to 14 stands, which are fastened to the build table at the correct spacing.
    The "ring" should be built first, installed in the tool which shapes the pod. The ring would have to be faired to the shape of the skin, before stripping starts. The ring should have a separator sheet placed on it before it is used to provide the required shape for the strips. Once the strips are complete and the glue dried, the interior tool and the ring would be removed.
    I'll be leaving the ring as an integral part of the fuselage. No need to remove it.

    Sorry if I'm being patronizing, but I am concerned.
    I really don't think your fears are warranted. However, thank you for the advice about how to build the strip planking part of the construction.
    Last edited by rtfm; 08-15-2021 at 07:49 AM.

  4. #39
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    Default Re: Cedar strip airplane

    Duncan,
    You certainly know small planes and this one infinitely better than I ever could.

    One last question: Will the inner layer of glass be continuous where the "ring" is located? I don't understand how you will not interrupt the glass in that area if the ring is integral.

    Having tried clamps vs staples or small nails with plywood pads I think your choice is best. There are boats done in a similar fashion, but which use much thicker "planks". These have plenty of stiffness to resist the weight of clamps, and may really require clamps, but the boats are much heavier - by intent.

    There is a quick way to use epoxy to bond together the strips. I have only done it on a test piece (about 4 feet of the nose of a kayak). You nail or staple the first strip in place. Then the second strip is stapled in place with a small gap. .020" for example.
    Continue fitting and stapeling strips on until done. Then use a syringe or brush to coat (and fill) the joints between the strips with epoxy. On a kayak the bottom part of the hull can be stripped in a day or two, instead of a week's hard work. Unfilled epoxy will easily flow into those gaps and saturate the wood edges. Let it cure, sand of any excess (pretty quick since the epoxy is localized), and you have the shell ready to finish sand and glass.
    The only issue with insuring there is enough epoxy is on the tapered ends of strips which is required due to the curvature of the shell. You should go back over the joints and add to any areas where the end grain has sucked up more epoxy - a real issue.
    The only reason you can't just leave any small depressions to be filled by the epoxy in the glass is the potential for amine blush - a wax like coating which occasionally forms. Amine blush will prevent bonding of the glass/ epoxy layer, and will show up as a yellow looking inclusion - only removable by removing the glass and sanding deep enough to remove it. Some epoxy's claim no blush, but there have been occasional reports of blush for those resins. Luckily blush is water soluble. Just wash with water and a green scrubie and it will be gone.
    The best thing about this technique is that you don't have to do the tedious fitting/ sanding of the edge to edge joint to make it fit. Just leave the edges square. If you are in an area of high curvature, you can just but the strips together, lightly, since there will be a V shaped crack to accept the epoxy. Less total work involved.

    One other time/ effort saving idea is to use a heat gun to pre curve the strips to fit your shape. This is easily learned. You can curve and twist a strip at the same time. Check to see if it fits, if you did too much or not enough, just do it again until it fits. After the first 2 you will probably get one done the first time. I generally work in 1' increments to make it easy to check. Just start from the middle of the strip.
    Don't use a hair dryer - the temperature is not high enough. Here in the US a cheap heat gun will produce 1000 or 1500F temperatures. I always use the high temp to get it done faster. Just don't charcoal the strip.

    Last suggestion. Wood is not always consistent. Big surprise. You will have everything stapled down perfectly and will find areas where the strips do not exactly match in height between formers. Use a staple going into both strips to bring them to the same height. You have to support them from the backside so they are level before you put in the staple. The biggest reason is that you will have to sand out any height differences before glassing or there will be a bubble. AND there will be another mismatch on the inside. After you sand out both sides the wood can get really thin - a local strength issue. Worst case you can sand thru the strips leaving a hole. Ask me how I know.

    Another last suggestion. I find a thick plastic under the head of the staple or small nail works better and cheaper than plywood for protecting the strips when you remove them.

    You have demonstrated that you know a lot more than was apparent in your first post.
    If I am repeating things you know, just call me a know it all and do your thing.

    Good luck.
    Marc

    PS: Thanks for the aircraft answers.

  5. #40
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    Default Re: Cedar strip airplane

    What you have shown us is a semi-monocoque construction. As above, the inner fiberglass skin must be continuous, wich means all structure (ringframes, bulkheads, stringers) must be glued in afterwards.
    There are a lot of stapleless construction methods, youtube is your friend. If you use staples you can sometimes close the holes with steam (clothes iron before sanding), but there is no guarantee.

  6. #41
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    Default Re: Cedar strip airplane

    Quote Originally Posted by narfiwillem View Post
    Two good places to start looking at plans/kits for wooden aircraft.

    https://fisherflying.com/
    https://www.teammini-max.com/

    I especially like the Fisher Dakota Hawk, but ultimately ended up starting an aluminum build with my son.
    Thanks. I'm familiar with both these companies, but I was interested something a bit more "substantial". I like these, but the build time is too long:

    https://buildandfly.shop/product/sequoia-f-8l-falco/
    https://www.ospreyaircraft.com/gp4.htm


    These are basically plans built aircraft (rather than kit built), so the builder needs to do it all. In the end, I settled for a boat. Perhaps, after I retire...

    Regards,

    Dean

  7. #42
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    Default Re: Cedar strip airplane

    Duncan,
    If you want to shrink the staple or brad holes, just use a spray of plain water.
    It will shrink the hole, but not always completely.

    When you finish sand the assembled strips, before glassing, spray down the strips with water.
    Light colored discoloring means some glue left you didn't sand off, dark colored lines mean scratches you didn't sand out.

    Once its glassed it is shocking to find those flaws which detract from your pretty wood grain appearance which you obviously want.

  8. #43
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    Default Re: Cedar strip airplane

    Quote Originally Posted by Rumars View Post
    What you have shown us is a semi-monocoque construction. As above, the inner fiberglass skin must be continuous, wich means all structure (ringframes, bulkheads, stringers) must be glued in afterwards.
    Now that is something I wasn't aware of. I'll do a few layups and measure the thickness of the glass fibre, and reduce the size of my permanent bulkheads by that amount. Thank you for that piece of information.

    Duncan

  9. #44
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    Default Re: Cedar strip airplane

    Hi,
    I came across this:
    https://www.clcboats.com/shoptips/st...ll-i-need.html

    The basic formula they use is:
    Number of WRC strips needed.jpg

    Anyone able to verify this?

    Duncan

  10. #45
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    Default Re: Cedar strip airplane

    Are you going to be using bead and cove shaped strips as in the calculator?
    After having done both bead and cove and square edged strips, I choose square edged.

    You get a little more width of strips with square edged, but the calculation is just about right.
    Of course, most of the strips are shorter than the full length of the aircraft (or any boat).
    So the 20% excess is included in the strips that are long.
    However, you will have to learn to splice short strips together on the mold to make use of the excess. Not a real problem, you just need to be aware and practice before starting your prized aircraft.

    Are you going to make any type of a pattern using dark and light strips? Example - an arrowhead on the belly of the plane.
    Easily done, but you have to plan. If so you will have to guesstimate the amount of dark vs light strips. You might search on kayak or canoe strip planked, and look at the images. Lots of creative ways to enhance your wood look. Some are really simple to do.

    Since you are doing this for the first time, I would suggest adding additional strips. You need to be able to throw a strip away if you just can't make it fit. ( or use that strip for a shorter position, and not completely throw it away).
    You also want to cut the thickness of all strips at one time so they will be identical. Resetting up the table saw setup for additional strips almost always ends up having two different thickness of strips, causing more sanding to get a smooth surface, and thinning your core (the wood).

    The formula is good, for people who have done this before. I would add more strips, but that is my ham- handed work experience. Especially if you are going to do bead and cove - I tended to break off the thin cove edges just moving the strips around.

    You should thank Rumars for his comment about continuous inside skin (I know you did). It is very important for good structure of this type.

  11. #46
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    Default Re: Cedar strip airplane

    Hi,
    Thank you. I actually plan to buy my cedar strips from Boatcraft Pacific - not too far from me. They supply strips 3m to 4m in length, and they come ready milled with a really substantial bead and cove profile. According to the formula above, I'm going to need 60m of strips @ $4.26 per lineal metre https://boatcraft.com.au/Shop/index....d44912b90d1e09 which is just over $255 for the whole plane. I'm very happy with that. I'll glue the strips together with Titebond Ultimate, since the integrity of the fuselage isn't in the core, but in the glass covering. No need for epoxy I think. Your thoughts?

    Patterns... I hadn't considered this.

    Yes, very pleased with the tip from Rumars. I'll be using West System epoxy with a couple of layers of glass fibre.

    One issue, however. I am trying to complete my current airplane. The fuselage is complete, and I'm about to start on the wings. To be fair to myself and to the people who are eager for me to get it finished so that they can evaluate its flying qualities and (hopefully) place an order, I am going to have to get it finished before I spread myself too thin by starting another build. Bugger.

    But I have a bunch of research still to do anyway...

    Warmly
    Duncan

  12. #47
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    Default Re: Cedar strip airplane

    The only reason to not use bead and cove is if you wanted to try the spaced strips which are glued together with epoxy after you fully strip the mold.
    Not conventional, so I expected you might not do that.

    You understand that when you need to bring a strip into a pre-existing one you are going to have to make a tapered cut on the end of the strip. Once you make the correct angle cut, then you are going to have to put the cove on that cut by hand.
    That is where I decided to never use that method again. You may find it is easier to cut your strips approximately in half so you can taper each end of the strip and still get it to fit for total length. Breaking the strip allows you to put a joint near the middle, which would be where the final fitting for that strip would occur. That guarantees the ends fit tight.

    Have you gone to look at a strip canoe or kayak? Take a look at how the strip ends are tapered in the ends of the boat.

    I suggest again that you find a mold for either a kayak or canoe, and strip the first 4' of either end.
    What seems theoretical becomes blindingly obvious.

    Please be sure to continue this thread when you do start to build this aircraft. I really want to see it. Thanks.

  13. #48
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    Default Re: Cedar strip airplane

    A last thing.
    2 plys of glass will obscure the grain of the wood.
    Make samples of one ply and two ply to see if you still like the wood look.

    If the main strength is in a steel frame you might not need 2 plys each side of the wood.

  14. #49
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    Default Re: Cedar strip airplane

    if you intend to put glass on either side, or both-buy enough"Peelply" to cover. ...after the cloth has been wetted out, cover the surface with the peelply and press in with the same roller that the resin was applyed with. ("peelply" might be known under a different name there) pp is layed over the matrex's surface and excess resin wicks thru the weve and comes off with the pp when it's pulled/peeled away, after curing.. excess resin only adds weight and very little strength. all thruout the build process you'll be constantly looking for ways to avoid weight.
    Last edited by the_gr8t_waldo; 08-15-2021 at 11:55 PM.

  15. #50
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    Default Re: Cedar strip airplane

    I've built and still use a WRC "stripper" canoe. It's mainly the fiberglass/epoxy skin that gives strength, not the core.

    Perhaps you could build a simple 8ft pram dinghy as a learning exercise? If the WRC is too expensive, you can use other woods.

    Dave

  16. #51
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    Default Re: Cedar strip airplane

    Lots of good advice above from the kayak building perspective. You wrote early up about having to build the various strip components as separate items, as in the case of the engine covers that need to be removable, etc.

    The easiest way to get fair lines on a kayak is to build it as a unit and then cut out the pieces that are to become hatches, or in the case of a break-down boat, the entire boat is built and then cut in half or thirds. Likewise on getting the interior glass continuous from bow to stern. The hull is built over formers, they are all removed, the insides are glassed, and then later in construction permanent bulkheads are installed.

    A final thought --getting a good looking clear finish in this type of construction does take some practice. Thinner epoxy and good quality fiberglass are musts. My first shot at it involved making a pram-style cradle for my grandson.

    I'm fascinated by the concept & will be following.
    -Dave

  17. #52
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    Default Re: Cedar strip airplane

    Hi,
    I'm considering building the cowl for my current project out of strip planking.

    This is an interesting build, because it is a sit-on design, completely cut on a CNC router. The frame is 15mm gaboon ply, and the skins are 3mm gaboon.
    Fleabike v2 Side view.jpg

    The fuselage is complete, with the tail fin having been bonded in place yesterday. The cowl still needs to be done, but I haven't quite decided how to do it. Looks like a possible candidate for an initial strip planking project. Small enough that it doesn't matter if I get it wrong, and big enough to give me some real practice.
    AFB v2 completed fuselage.jpg

    This one will be painted.
    Duncan

  18. #53
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    Default Re: Cedar strip airplane

    An engine cowling in particular, is subject to temperatures that might degrade the epoxies that we boat builders use. One very popular system has a heat deflection temperature of 123F. That means that itís beginning to soften.
    Iíve had glass-epoxy composite parts collapse when they were left in the sun on a warm day.
    This is a specific risk that you need to evaluate.

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    Default Re: Cedar strip airplane

    Mmmm I wonder what the composite plane guys do - I'm pretty sure their engine covers are composite. I'll check. Thanks for the heads-up.

    Duncan

  20. #55
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    Default Re: Cedar strip airplane

    Just saw this on Reddit:
    A strip planked corset.

    Cedar Strip corset.jpg

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    Default Re: Cedar strip airplane


  22. #57
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    Default Re: Cedar strip airplane

    Thread drift, but not a bad one

  23. #58
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    Default Re: Cedar strip airplane

    Hi,
    I'm still at the conceptual drawing stage, but I need some practical advice. If you refer to the screenshot below, you will see my current thinking about how to anchor the rear wing. Basically, the red bits are the 9mm ply bulkheads, to which I want to fasten the 40mm square steel wing "masts". Obviously, these two masts need to be very securely anchored to the aft portion of the fuselage, so I want to tie the bulkheads into three longerons (stringers) of 19mm x 19mm Hoop Pine.

    Aft bulkheads.jpg

    The steel masts angle outwards, so they do not actually come into contact with the longerons - only the bulkheads.

    Question:
    I was intending on including 19mm deep recesses in the formers to accommodate the hoop pine longerons so that the cedar strips would lay flat against them (and be bonded to them). So far, so good (I think). But when it comes time to glass the inside of the fuselage, I will have three 19mm longerons rising 19mm proud of the inner surface. It strikes me that glassing over these protrusions is not going to be that easy. Do I glass the inside first, and add the longerons afterwards? Seems like a difficult thing to do, but I seem to recall seeing inwales (is that the right word?) done in precisely this way.

    Suggestions?

    Regards,
    Duncan
    Last edited by rtfm; 08-18-2021 at 07:33 AM.

  24. #59
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    Default Re: Cedar strip airplane

    Glassing in one long run (flat) is to take advantage of continuous lengths of Fiber fixed to the surface. If you have to go round stuff you lose the benefit, it will be a weak spot.

    you can wrap the parts in cling wrap or some such material and build with them installed. The glue won't stick to the cling wrap so the component should come away easy when you need to glass. Packing tape also works as a releasing agent, use it on your form edges to stop the strips gluing to the molds.

    when gluing up your strips concentrate on aligning the inside faces as well as possible, sanding the inside fair for glassing is much harder than sanding the outside. The neater you can do the inside the less work you'll have.

    Staple holes are only an aesthetic consideration and not a big one in my opinion.

    Exciting project, remember pictures are greatly appreciated.
    It's all fun and games until Darth Vader comes.

  25. #60
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    Default Re: Cedar strip airplane

    what purpose/use is the space behind the pilot serve? it strikes me that instead of mounting the wing/elevator to an "A" framed support post of steel, you might consider "dovetailing" it into the fuseloge structure it's self and do away with the reliance on a steel posts and possibly a bit of wing support structure inside of the area.as well. sorta "channeling the stresses into the strip built fuesaloge rather than to an inverted "a"post- a particularly long one, at that (in the end that's where they ultimatly end up at, anyway.) a slight change of "strip" lay up schedual- at this point of your construction/planning, could be done rather painlessly. after the fuse. is removed from it's mold any fiberglass patches/reinforcements could be easyly added by simply rolling ( gently, of course) the fuse into a position that aids the craftsman to do the needed work
    Last edited by the_gr8t_waldo; 08-18-2021 at 11:01 AM.

  26. #61
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    Default Re: Cedar strip airplane

    It strikes me that glassing over these protrusions is not going to be that easy.
    You are correct on that point. The glass will not willingly conform to sharp bends or inside edges.

    I don't think it has been mentioned yet in this thread, but the composite wood construction bible is The Gougeon Brothers on Boat Construction. Offered free online now. There's pretty much all you need to know, at least as it applies to boats, plus some engineering information. The Gougeon brothers were laminated wood pioneers who developed techniques for constructing large wind turbine blades as well as boats.
    -Dave

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    Default Re: Cedar strip airplane

    Quote Originally Posted by Woxbox View Post
    You are correct on that point. The glass will not willingly conform to sharp bends or inside edges.

    I don't think it has been mentioned yet in this thread, but the composite wood construction bible is The Gougeon Brothers on Boat Construction. Offered free online now. There's pretty much all you need to know, at least as it applies to boats, plus some engineering information. The Gougeon brothers were laminated wood pioneers who developed techniques for constructing large wind turbine blades as well as boats.
    they built aeroplanes too
    lots of info and articles on aviation applications for wood epoxy and wood foam composite construction in their free online magazine 'eppxyworks' archives available on line through their website
    Simpler is better, except when complicated looks really cool.

  28. #63
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    Default Re: Cedar strip airplane

    Quote Originally Posted by gypsie View Post

    Staple holes are only an aesthetic consideration and not a big one in my opinion.
    Sounds like it might be true but experience tells me it is not a minor consideration at all. I was part of a team building a racing trimaran some 30 year ago. We thought the launching a big enough deal to have the local TV people there with their cameras. Everything went swimmingly and finally the TV people left but not a moment too soon. The poor boat was sinking and the culprit turned out to be staple holes not filled by epoxy coatings in laying up the laminated arc circular bottom of the main hull. We managed to get it to sail to shore and then emptied of a disgusted amount of brackish water.

    Surface free energy is not just something to confuse a college student but a real effect to be reckoned with when holes or any sharp edge is encountered by epoxy or any liquid finish. Forcing thickened epoxy into the myriad holes or cracks with a squeegee by chastised glass eliminators became a new skill.

  29. #64
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    Default Re: Cedar strip airplane

    staple holes in cedar strip canoes are covered with glass cloth set in epoxy resin
    Simpler is better, except when complicated looks really cool.

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    Default Re: Cedar strip airplane

    Quote Originally Posted by the_gr8t_waldo View Post
    what purpose/use is the space behind the pilot serve? it strikes me that instead of mounting the wing/elevator to an "A" framed support post of steel, you might consider "dovetailing" it into the fuseloge structure it's self and do away with the reliance on a steel posts and possibly a bit of wing support structure inside of the area.as well. sorta "channeling the stresses into the strip built fuesaloge rather than to an inverted "a"post- a particularly long one, at that (in the end that's where they ultimatly end up at, anyway.) a slight change of "strip" lay up schedual- at this point of your construction/planning, could be done rather painlessly. after the fuse. is removed from it's mold any fiberglass patches/reinforcements could be easyly added by simply rolling ( gently, of course) the fuse into a position that aids the craftsman to do the needed work
    Hi,
    These are interesting observations. The *main* reason for the space behind the cockpit is to accommodate the plan view, which requires it. I can't chop off the space behind the pilot without also chopping the plan view, which would not be a good idea. But I could use part of it as a storage area - although I will have to keep this storage area relatively small because I can't risk the centre of gravity being moved too far aft.
    Top and side view.jpg
    Generally speaking, wing struts are made from 25mm circular steel tubing, frequently encased in an airfoil shape. I investigated building struts out of wood, but the tensile strength wasn't sufficient, which meant the wooden struts would need to be too massive. The airplane will weigh somewhere in the region of 300kg all up (with me in it). The struts are mainly in tension, but also have to withstand compressive forces. At 4G, that's 1200kg. Hence the steel, and wanting to lock this into a bulkhead anchored solidly to three longerons, since bonding the bulkhead to the cedar strips only is not going to provide sufficient security. I'm thinking I might have *two* bulkheads, one on either side of the 40mm steel strut.

    Cheers,
    Duncan

  31. #66
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    Aug 2021
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    Default Re: Cedar strip airplane

    Quote Originally Posted by Woxbox View Post
    You are correct on that point. The glass will not willingly conform to sharp bends or inside edges.

    I don't think it has been mentioned yet in this thread, but the composite wood construction bible is The Gougeon Brothers on Boat Construction. Offered free online now. There's pretty much all you need to know, at least as it applies to boats, plus some engineering information. The Gougeon brothers were laminated wood pioneers who developed techniques for constructing large wind turbine blades as well as boats.
    Hi Dave,
    Thanks for the link. I'll spend time today reading it. Actually, last night I watched the OrcaBoats video of fitting the inwales on a kayak. Gosh - LOTS of work...
    https://www.youtube.com/watch?v=SYQcMfq2-Nc

    My main concern is ensuring that the bulkhead to which I attach the wing spar is very securely attached to the rest of the aft fuselage - which is why I want three stringers/longerons. If I can bond these three longerons securely in place, I can notch the bulkhead so that it keys into the longerons and then bond it in place.

    Regards,
    Duncan

  32. #67
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    Aug 2021
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    43

    Default Re: Cedar strip airplane

    Quote Originally Posted by Sandlapper View Post
    Sounds like it might be true but experience tells me it is not a minor consideration at all. I was part of a team building a racing trimaran some 30 year ago. We thought the launching a big enough deal to have the local TV people there with their cameras. Everything went swimmingly and finally the TV people left but not a moment too soon. The poor boat was sinking and the culprit turned out to be staple holes not filled by epoxy coatings in laying up the laminated arc circular bottom of the main hull. We managed to get it to sail to shore and then emptied of a disgusted amount of brackish water.
    Ha ha. What a disaster, and an excellent escape! The OrcaBoats video was interesting in how he kept the strips attached. He used zillions of strips of masking tape to pull each successive strip tightly against the preceding one. Seems a good idea...

  33. #68
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    Feb 2006
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    9,353

    Default Re: Cedar strip airplane

    If you don't like staples, you can tie down the strips with monofilament or synthetic sinew wrapped over the strips and then back around screw heads in the formers. After the glue sets, it's easy to cut the line and pull it free of the structure. It slides right through the joins no problem. The line also provides more tension where needed than a staple. There's all sorts of ways to skin this cat.
    -Dave

  34. #69
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    Mar 2021
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    Oriental, NC ,usa
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    127

    Default Re: Cedar strip airplane

    Quote Originally Posted by Paul Pless View Post
    staple holes in cedar strip canoes are covered with glass cloth set in epoxy resin
    You are undoubtedly talking about small staples and relying on coating the wood strips with enough epoxy to stop water entry. A layer of glass and epoxy did not prevent the trimaran from taking on water. The larger staples that penetrated both layers of the wood mold could not be filled with normal epoxy coating. It is a different case with different materials but still....

  35. #70
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    Aug 2021
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    Brisbane, Australia
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    43

    Default Re: Cedar strip airplane

    The Gougeon Bros book was a fascinating read - especially the section on how to ensure a completely clear glass covering. Thank you.

    Duncan

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