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Building Tips and technical articles. => Building techniques => Topic started by: Dwayne on October 19, 2009, 12:25:31 PM
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Hi could someone please post pics on how to mount landing gear in a foam wing.
Thank you
Dwayne
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can do easy
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Thanks Paul
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You just axed for pitchers, but here's little text to go along with them.
What I have here is a box beam spar that mounts both the landing gear and the bellcrank, and also joins the two wing halves. It's mostly balsa except for the hardwood channels for the landing gear and the hard points for the bellcrank. The landing gear is my standard torsion bar setup with the wire twisting in the channel and an anti-rotation bend near the centre of the wing.
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Paul's setup is certainly strong, but here's another method that has proven to be far more than strong enough and is by far lighter and easier to install.
I developed the method of installing 1/8 inch thick landing gear "clips" or ribs that but up against a full-depth spar at the rear and sit flush with the surface of the core, allowing the wing sheeting to contact them and impart strength to the entire assembly.
I layout and cut 1/8 inch slots from the leading edge back to the full-depth spar and then insert a piece of 1/8 inch Lite-Ply into the slot. I trace around the wing shape onot the plywood and then remove the plywood and layout "lands" onto which custom built landing gear plates will sit later on. It is extremely light and requires very little foam be cut away in order to install the clips or plates. I've performed this procedure on hundreds of wings since developing the method in the early 1970s. I've never had a landing gear failure with this method, not has any of my customers reported any failures. In fact one of my customers recently had a stooge release his model before he was out to the handle. The model actually got airborne before my friend grabbed the down line out of the air (lucky grab!). The model abruptly hit the ground at speed right on the landing gear. The impact bent the outboard landing gear back far enough that the rear end of the wheel pant went clean through the UPPER surface of the wing! The gear wire was bent, but the mount din't even crack! He re-bent the gear, fixed the wing covering where the wheelpant had punctured through and he is still flying that ship. He says he'll never use any other gear mount method!
Hopefully the photos will tell the story. One of them depicts the finished system with cover/gear retainer plate already in place on a built-up wing. It works just as well in a built up system as it does in a foamer!
Later - Bob Hunt
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Thank you Bob
Dwayne
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The system shown can be modified to accept either a maple block with a slot in it for the landing gear wire, or for a plate that has basswood strips attached to it to form a channel for the wire. I use the latter because it is lighter. I don't have any photos that depict the way the plate system is fabricated, but I will document the next one I do and post it here.
This system is thoroughly explained and depicted in step-by-step detail in my company's Lost-Foam DVD set. See my Robin's View Productions page elsewhere on this forum for details on that.
Attached is a photo of the finished system in the Caprice just before painting.
Later - Bob
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Sorry for dragging up this old thread, but I figure it's probably the best place to tack on a few more questions.
Hopefully, If you're around Bob, you could help me get a bit of a better understanding of things.
One thing that's twisting my noggin is the method of securing the torsion bar upstand in the wing? are you mounting a plate near the top surface on the wing or is there something else keeping that upstand in the right place? I take it your cover plate is ply with a balsa fairing fitted to match the shape of the wing?
Another query is the main spar, is that just butt joined at the centre section?
Thanks,
Greg
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Hi Greg:
I published a How-To on this in Stunt News a few years ago. I could not find the text I used there, but I do have the photos in sequence and I think they tell the story on their own without the need for text.
I'll post about ten per response so that I do not exceed the limit per response.
Here goes the first ten...
Later - Bob Hunt
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Here are the next ten photos...
Bob
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...and ten more.
Bob
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...and ten more yet...
Bob
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and 41 to 50...
Bob
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Here are 51 to 60...
Bob
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And here are the last of the photos! #^
Bob Hunt
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Bob, thanks so much for that, not only is the detail easily followed the photography is perfect and the building is sublime.
If a picture is worth a thousand words, I think I owe you about a million after that.
I beleive I am ready to stick some wheels out of my wing!
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;D
Bob
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Excellent tutorial in pictures. Nobody does it better. Not sure if anyone else does it period. I didnt need the lesson, but that was a perfect response with all the answers and not one sour note.
Kudos Mr. Robin
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;D ;D
Bob
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Now you know why he one of the greatest in this hobby/sport. #^ #^
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8)
Bob
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Excellent tutorial in pictures. Nobody does it better. Not sure if anyone else does it period. I didnt need the lesson, but that was a perfect response with all the answers and not one sour note.
Kudos Mr. Robin
oh yeah,, well take this,,
Lemon drops
hows THAT for a sour response,, muah hahaha S?P
well done Mr Hunt,,
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If someone gives you lemon drops, make, uh, lemon drop aid...?
Thanks Mark, John and Doc for the comments. I have developed the habit of taking photos of virtually everything I do in the shop. It's amazing just how many How-To possibilities there are, but you need the photos to illustrate them. I'd suggest that everyone keep a digital camera charged and at the ready to record progress on a model. y1
Later - Bob Hunt
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If someone gives you lemon drops, make, uh, lemon drop aid...?
Thanks Mark, John and Doc for the comments. I have developed the habit of taking photos of virtually everything I do in the shop. It's amazing just how many How-To possibilities their are, but you need the photos to illustrate them. I'd suggest that everyone keep a digital camera charged and at the ready to record progress on a model. y1
Later - Bob Hunt
Bob, I keep a camera charged and at the ready, in fact I take lots of pictures,, but my model got really upset when I told her I was posting pictures of the progress I was making ,,
oh wait, different model huh,,
dang
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Fantastic tutorial in pictures Bob! Thank you.
I really like the baby flush cut saw xacto blade. What is the number on that one?
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Thanks, Mark!
Not sure what you meant about the flush-cut saw blade. To which photo number in the sequence are you referring? I'll help if I can. The long blade in the #2 handle is the #26 Whittler's Blade (my second favorite tool after the Solingen Razor Plane...).
Later - Bob
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Thank you Bob. I was looking at 38 and 39 where the parts were being brought to flush with the wing surface and immediately thought of a flush cut saw. They are springy and work great in the right situations but probably more for door jams then models I admit. ::)
I will have to try that blade.
-Mark
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Hi Mark:
You know, I never thought of trying a flush-cut saw (didn't even know the actual name for that tool until I read your post...). There are probably a lot of applications for those in modeling. y1
Thanks - Bob
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Bob
I always have my cāmera, and take a lot of pics..
Why is it that they don't look as good as yours??? LL~ LL~ LL~ LL~
Bob's how-to are the best in business.. and free for all!!
Not only a great builder/finisher and pilot, but a role moddel...
Marcus
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Marcus, it takes practice and more practice. I don't think I could live long enough to get the experience our Bobby Hunt has. Read the latest editorial in Flying Models I just received yesterday.
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Bob,
I have a cross cut flush cut Japanese style pull saw that I love when I get to use it. It is thin and cuts very quickly. I don't think you would even have to grind a safe edge on it, like the corners of a file, because none of the teeth kick out.
Mark
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That sounds great, Mark; do you have the address of a website at which I might purchase one of those?
Thanks - Bob
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Bob,
Here is one at Lowe's http://www.lowes.com/ProductDisplay?partNumber=375302-281-213103&langId=-1&storeId=10151&productId=3612246&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1 (http://www.lowes.com/ProductDisplay?partNumber=375302-281-213103&langId=-1&storeId=10151&productId=3612246&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1)
Same sort of saw http://www.lowes.com/ProductDisplay?partNumber=88288-414-BS250D&langId=-1&storeId=10151&productId=1103271&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1 (http://www.lowes.com/ProductDisplay?partNumber=88288-414-BS250D&langId=-1&storeId=10151&productId=1103271&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1)
Mine is not on its hook and is hiding somewhere in the garage right now otherwise I would check the brand.
Mark
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Just bumping this to the top. I've received a number of requests for information on landing gear systems and how I do them. There is a photo essay here that shows how I make and install my landing gear systems and how I make the form-fitting covers that match the airfoil.
Later - Bob Hunt
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we share our grass circles with little critters that like to make holes, i have a hunt scorpio wing with wing mounted gear that i increased in size to 5/32 ,.after 3 years it is still as tight in the wing as it was the day i put it in.
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Actually, your timing for this (at least for me) is perfect, Bob. Thank you. :)
And for that matter, thanks for all the "how-to" posts and guides for building that you've put together over the past few years. It's made my slow-but-steady most recent build a lot less frustrating and a lot more rewarding.
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Anther "Thanks" to Bob for the great tutorial. This should be a "sticky".
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I agree, this topic would be a good one to "sticky" at the top. Who could do that? Hmmmm. Sparky, Randy, or maybe Bill Little?
I was wondering about putting a "plug-in" wire gear into either a foam or built-up structure, the way the the Ukrainians and others do. All I've got is a picture of Mike Haverly's plug-in tailwheel strut (see picture). I was thinking it would fit nicely against the spars and cause less interference with leadouts, tho you'd still want some plywood ribs to spread the load into the LE sheeting and LE cap, if one is used. The nicest thing is that you'd have a spanwise slot in the LE sheeting instead of the chordwise slot as I've seen in Eastern European stunters. It even might be possible to put some torsion bar in it, somehow, but I'm looking for ideas. And maybe instead of wire...molded CF? ??? Steve
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I have a question for Bob or any of you that think you can answer it (I hope its not too obvious, but I'm tired tonight!).
Why is the balsa block that holds down and boxes in the main landing gear mount plate wider at the wing inboard end than at the outboard end? I'm just curious if there is a structural reason for that? Because of more twisting force imparted?
I also am wondering if the main plate is "Lite Ply". It looks to be 1/8" light ply, with basswood strips forming the slot.
Last question is what thickness and material is the inner plate that bolts in. It looks like thinner regular ply to me, maybe 1/16" or 3/32" thick.
Thanks! That is an awesome picture essay.
Bob brings up a great point about documenting build. Not only are they useful for others, I have found them to be helpful to my own (RC) projects that I might sideline for a 2-3 year period. When I bring them out, if I have a build thread going, I just look back and refresh myself with what the plan was. Especially helpful with sheeted/v-bagged foam cores that later have servos to be installed in specific places.
R,
Chris