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Post by sgmason on Jan 27, 2013 22:58:04 GMT -4
I just came up with another idea, I could build my own high wing trainer out of foam board and pick up the electronics locally. I am thinking something like this mikeysrc.com/Sport-Trainer.html, but I would make an actual airfoil for the wing and add a rudder. I have the fiberglass spare from the broken wing to add stiffness, and I would box in the fuselage for a bit of electronics and battery safety.
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Post by osidak on Jan 27, 2013 23:21:15 GMT -4
nothing wrong with building your own. just use a recognized airfoil and you should be ok
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Post by sgmason on Jan 27, 2013 23:27:05 GMT -4
A foam board airfoil is pretty easy to do. Just take a look at the flitetest baby blender. My problems will come when its time to picking out the electronics to power it, esc and motor. I want to make a stable gentle 4 channel flyer that actually looks like a cub. I will start designing tomorrow after I do some painting
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Post by Dr. Evil on Jan 27, 2013 23:46:29 GMT -4
A foam board airfoil is pretty easy to do. Just take a look at the flitetest baby blender. My problems will come when its time to picking out the electronics to power it, esc and motor. I want to make a stable gentle 4 channel flyer that actually looks like a cub. I will start designing tomorrow after I do some painting That would be awesome G, keep us updated on your progress....love to see this come all together for ya buddy.
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Post by sgmason on Jan 28, 2013 0:01:53 GMT -4
Well I just went and checked out parts on HK. If I want to stick with 3-4s power, and 4 channels I would be looking at a $120 total build for everything including shipping and an orange Rx so I don't have to steal one from something else. I also included a couple extra 9g servos in that because you never know when you may need another servo for something stupid. The designing phase will be easy enough, I have a decent 3D CAD program, so I just draw up what I have in my mind, then roll out the surfaces to see how much foam board I would need. It also gives me the chance to do any edits before putting knife to foam. Hopefully the experience plank guys will speak up and offer suggestions when I actually get the basic design done. I am going to kick back for the night and watch the new Top Gear UK then its bed time for this bonzo ;D
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Post by sgmason on Jan 28, 2013 16:04:46 GMT -4
Ok so I have my 3D drawing done, just need to roll it out to make the layout for the foam board. I am not too sure on the cowl area, I will have to adjust it after I figure out what size motor I will need. Dimensions are in inches and I haven't added the flaps yet. I am still trying to decide on if I will ad a dihedral or just kick up the wing tips a bit I plan to make the landing gear struts out of aluminum sheet I have laying around, and the wing struts will be BBQ skewers that will set into small tubes with set screws. the wing will be held down with the standard crossed elastics. I will need to ad a bit of light ply or something of the sort to mount the electronics to and make a motor mount. the battery hatch will be just behind the landing struts and held shut with either a magnet or Velcro. With the wing span being 50" I will probably need to make it as 2 half wings and join it with a pair of spars in the middle. I may have made my ailerons a tad long to be able to put effective flaps on at some time. Now to figure out where my CG point needs to be for it to fly properly. I know I read up on it some where I just can't remember where it was Any suggestions on my rough design let me know.
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Post by Dr. Evil on Jan 28, 2013 16:36:23 GMT -4
WOW! Mr. Airplane designer....keep up the good work. Looking forward to the final product!
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Post by sgmason on Jan 28, 2013 17:11:55 GMT -4
Drawing it up is the easy part, unwrapping the UVs to get a true flat plan is the hard part. To draw it all I did was find a picture of a Piper Cub with front, side, and top views. I brought those into my 3D cad program and put one view in each window then traced it Now that i have it drawn I have to flatten it out, without actually changing the dimensions of the curved parts or distorting any of the lines. Once I have that done I have my layout for the foam board and I can figure out how many sheets I will need. The horizontal and vertical stabs are the easiest because they are flat. The wing is the hardest because it is an airfoil. Will it all work once I get it figured out and built remains a mystery ;D
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Post by Valkman on Jan 28, 2013 17:28:46 GMT -4
Why build when you can have one sent to your door for about the same money? Im looking at the grasshopper from the UK to me all in is $130 all in which is about what you are going to spend. If your are going to build one thing you have to keep in mind is the type of foam you are going to use.
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Post by sgmason on Jan 28, 2013 17:47:50 GMT -4
I like to create If I build my own grasshopper I get a sense of satisfaction that I can't get from buying a kit. Then there is the replacement parts, if I break a wing or something like that I just pick up another sheet of foam board and make a new one. Thats a lot cheaper than having to order another from HK. As to what type of foam I will use, it is usually depron foam that has poster board glued to both sides. It is fairly stiff on its own and durable too thanks to the fibers in the paper. Prices range from a buck or so at stores like Dollar Tree, to $20+ if you go to a art or business supply store I am lucky enough to have a Dollar tree store not that far away
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Post by sgmason on Jan 28, 2013 21:19:17 GMT -4
Well I have it roughed out, and with a 50" wing span I need 3, 40X20 inch, sheets of foam core. I was going to head out to Dollar Tree tomorrow, but we have an ice rain warning for the next 3 days, so I most likely wont make it out till next week. This is what it will look like laid out on the three sheets. If I could find 50"X40" I could do it on one piece. Tomorrow I will start working on creating a 1:1 printable PDF so I can get the patterns ready
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Post by osidak on Jan 28, 2013 22:17:49 GMT -4
why foam - why not wood?
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Post by sgmason on Jan 28, 2013 22:25:50 GMT -4
Its cheap and easy to repair. I looked at a couple of wood kits and decided with my crash record foam core was the more resilient option.
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Post by sgmason on Jan 29, 2013 1:09:40 GMT -4
Apparently anyone who decides to build a Piper cub from scratch comes up with the same thing. I had never seen this before I started my design, but it pre dates mine by a "few" years. Funny thing is he made his design the same way I did, a three view picture and went from there. I guess that is why they look almost identical www.rcgroups.com/forums/showthread.php?t=1028141I am going to continue with my own design, but if mine doesn't fly like I want I can always take his plans and upscale them to the size I want.
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Post by Valkman on Jan 31, 2013 6:08:31 GMT -4
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