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Kits Scratch Build Balsa Plane

Discussion in 'Airplanes' started by Rc-Help Member, Nov 19, 2011.

< Extra 300 Foamy | 3D Hobby Shop Edge 540 >
  1. Rc-Help Member

    Rc-Help Member I Love This Site!

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    I have been searching for the balsa plans for either a scratch build Edge 540 or a Extra 300 with a 48+ inch wingspan (I know i can scale it to what ever). I found a kit for a Edge 540 Stevens AeroModel Edge 540 but i can't find the plans. I'm trying to find something to do this winter just to test my building skills. If you run across a set some where let me know. I've found a set for the following

    Ultimate Bipe
    Amp Jr
    Cap21
    Cap231
    Little Extra (not bad)
    P51-B
    P52-D2
    P52-pony
    Slick280 (not bad)

    So if your interested in trying one of these let me know and I'll senf you either a pdf or a dxf drawing.

    Thanks
     
  2. Tony

    Tony Administrator Staff Member

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    I may be interested in some of these. Like the Bipe and the 51. Can't wait to see what you decide to build.
     
  3. Rc-Help Member

    Rc-Help Member I Love This Site!

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    Well I found the silhouette of the 540, i just got to figure out how I can scale it out for a decent plan. I'm going to see it I can get someone to blueprint it for me to size. If you want any on the other plans let me know and I'll point you in the right direction. I've already downloaded the dxf and converted them to pdf.
     
  4. Tony

    Tony Administrator Staff Member

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    I will take them and print them out in full size on my plotter. Should make it a little easier to cut and print.
     
  5. Rc-Help Member

    Rc-Help Member I Love This Site!

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  6. rdsok

    rdsok Well-Known Member

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    Well... I found something that may help you get to where you want to go... sort of.

    Here is a set of 46" plans for a foamy version that is built similar what you may want and looks ripe to be converted to a balsa plane with just a bit of work... here is the thread I found them in... Big 46" EDGE 540 (The next step after BFU) - RC Groups


    Now for some additional info just so you are going into this with your eye's wide open... Building from scratch or even a kit seldom can save you any money these days. The costs for the materials is not as cheap as it once was and the kit/ARF makers can buy in such bulk, we can't get wood and the other hardware as cheaply as they do. So the people that still do this .... do so because they enjoy that part of the hobby. I know I did on the two I built from kits but I don't have the time or place to do it again at the moment.

    On the wing... the main spar normally is placed just in front of the CG line... look at your 3DHS Edge as an example/model.

    When my Dad was cutting out ribs... He'd make an inner rib and outer rib template, then stack all of the balsa for the ribs in-between these and then use his band saw to rought cut them all at one time including the notches where the spars go through. Don't forget to drill the hole for the wing tube before you seperate the ribs from the templates you make ( if you use that method ). He would then sand them down to the final shape by hand using a block of wood with sandpaper wrapped around it. Also remember to allow for the thickness of the sheeting you are going to apply to the front leading and rear trailing edges.

    They also make some balsa sticks that can help a little bit. They have "D" shaped pieces you can use for the leading edge as well as some trailing edge pieces... they will save you some sanding if you use them.

    On the tail pieces... airfoiling them will make them stronger and less prone to flutter but they add weight and are obviously more complex to build. If you go with flat tail pieces... try to use harder balsa to give it added strength... Typically you'll be hard pressed to get much choice here but it is something to keep in mind if you can.

    Hope some of that helps a bit...
     
  7. rdsok

    rdsok Well-Known Member

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    Forgot to mention... Hobby-Lobby.com is probably the cheapest source I found for wood. Another good source is Tower Hobbies but they are a bit higher priced.
     
  8. rdsok

    rdsok Well-Known Member

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  9. Rc-Help Member

    Rc-Help Member I Love This Site!

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    Yeah.. Thanks that helps a lot. I know it is going to take some time. I'm pretty handy with wood crafting I worked in a cabinet shop for about 10 years. I wish I had a laser. Guess I'll have to use the ole scroll saw and dremel. I have most of the necessary tools. I'll probably get a half sheet of 3/4" plywood to make my work top out of. i also have two dremels, a table saw, a joiner, drill press, disc sander, router with table and assorted bits and a few other tools that will help in shaping the wood. I'm not trying to be cheap, I just want to see what I can do from scratch. Thanks for the tips and I'll check hobby lobby for the wood items. I have one of the large hobby lobbies pretty close. I've priced some of the pre-cut kits also and they range from $200 to $500 for 50" and above. It should keep me busy and be fun.. lol
     
  10. Keith

    Keith New Member

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    I've just started a scratch build.... Hawker Fury Bipe.... Just finished all the ribs for the top wing... I cut my templates from aluminum sheet... Cut out some balsa blanks and bolt them between the two templates, then sand away... They come out perfect, just don't sand too hard when you get to the aluminium... I then file out the spar notches and drill holes to save weight....

    I made a table saw for my dremel and am using all sheet balsa... I can cut any sized spars I need up to 10mm thick... The saw only just cuts 5mm so I turn wood over for deeper cut.. I am using a set of plans I found in an old magazine... I photocopy each section as I build it, the plans are a bit fragile... Biggest prob so far is working out metric from imperial... I'm using 5mm for 1/4 inch and working from there so I should come out a bit lighter than the plan says.... Will get pics when I get a chance....
     
  11. Rc-Help Member

    Rc-Help Member I Love This Site!

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    Cool Keith, keep us posted on your progress. I haven't even got started I'm still in the planning stage.

    My current Edge 540 has a wing span of 41'. If I want to scale that up to 51" it comes out to about a 25% increase in the size. 41' x 1.25 = 51.25"

    I'm wondering if I increase all the outer measurements by 25% if all the stuff will match up and fit together.
     
  12. rdsok

    rdsok Well-Known Member

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    I know there are several areas than need addressed when rescaling a model but I can't give any specifics since it isn't an area I'm familiar with from experience or that I've read much on so I have to rely on just "Southern Engineering" principles... LOL :D

    There are considerations in strutural strength for the materials being used. The increase in mass results in gforces that often exceed what a smaller model can handle easily requiring stronger materials in the areas affected in the larger model.

    3DHS has recently released a new 48" Edge where they changed the horizontal/vertical stabs etc over too airfoiled versions from flat. They also went from CF LG on the 48" to the steel rod type that the 41" has had great success with, but are having minor reports of strength issues when using them on the larger version. They also had an older 55" version and upscaled to 58", the redesign has taken over a year to get from the drawing board, through prototyping to distribution.

    Hobbyking recently, last year or the first of this year, released a SBach made by some company that I've already forgotten the name of.... It was almost a complete bust with the majority of the complaints saying the model comes out very tail heavy... Turns out they had simply scaled down a larger model that did work well but didn't prototype it as a smaller model before starting to sell them... The only guys that were successful flying them did it by rebuilding the tail surfaces lighter and then the model still had a higher wing loading than they cared much for.

    Another area that must be addressed is the power plant. I'm not sure if the increase in power must be logarithmic or exponential but I do know it isn't a linear increase. The way I've always heard this refered to is that "the air doesn't scale"... in otherwords the drag increases for the size of the model and that the lift produced by a wing type differs as well but not linearly.

    I know my father has rescaled many planes in the past and usually doesn't have much trouble but he had been doing it since before I was born also, so I suspect he just naturally makes adjustments during the building and probably doesn't think about it much these days. The following are areas that I'd think ( but not know for certain ) that should be addressed...

    Beef up the landing gear and the LG block area. Not only building just the immediate LG block stronger but also spread out the forces it will need to take both forward and rearward from the block. I used two carbon fiber tubes that extend from the F1 former ( the former the motor box sticks out from ) to the former just behind the LG block area along with some CF sheeting in the LG block itself on my 51" Slick to do just this... works great. On the last bad landing I made ( was having elevator issues in flight ), I came in very hot on landing and my gear sheared off cleanly without damage to the fuse. I suspect the same landing on an unmodified LG block area would have ripped that whole area out instead.

    A slight increase in the strength/size of the wing spars to handle the additional mass of the plane better. Do a similar increase in strength on the tail surfaces either by going with airfoiled pieces or by using harder wood like bass wood in some of the key areas here near where they attach to the fuse.
     
  13. Keith

    Keith New Member

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    Here are some pics of the Dremel table saw which can be used for router/sander table as well...

    Top wing ribs and tailplane...



    Fury 006.jpg Fury 007.jpg Fury 008.jpg

    Fury 006.jpg

    Fury 007.jpg

    Fury 008.jpg
     
  14. Tony

    Tony Administrator Staff Member

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    Very interesting there Keith. That is a great idea when working with lightweight and fragile boards. And being able to take a sheet and make your own ribs is a great idea.
     
  15. Keith

    Keith New Member

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    And you can always make a couple of extra ribs because I have not built a plane yet where I have not broken a couple...
     
  16. Rc-Help Member

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    Slowly getting ready to start my balsa build. I got a scroll saw for Christmas and I have been shopping for places to buy my wood products. I found a online store with pretty decent prices on wood. It is rcfoam.com they have just about everything I need to get started and the prices are good too. If you have any suggestions on wood sizes, plywood or not, or jig ideas please let me know. I want to build a Edge 540 30 sized airplane which will put the wing span at about 52 inches.
     
    Last edited: Nov 28, 2011
  17. Tony

    Tony Administrator Staff Member

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    That will be about the same size as the Edge I have. You will love it when it's done.
     
< Extra 300 Foamy | 3D Hobby Shop Edge 540 >

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