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Old Jun 26, 2012, 05:55 PM
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United States, NV, Reno
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Sig Riser 2M Build

I am starting a Sig Riser. Although I have seem many positive reviews I have not seen much on the build process. I am going to be doing a stock build (more or less) unless their is something that will yield a big benefit for not too much work as I am a 1st time builder.

Any tips are appreciated.

Current Status is that I have started the inboard wings and will be posting pictures shortly.
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Old Jun 27, 2012, 07:23 AM
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Please post pictures as you build. I am interested in seeing how this one goes together. Thanks.
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Old Jun 27, 2012, 03:23 PM
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Photos 1st stage inboard Wings

Here are the inboard wings. I had some trouble with these; however, in the end I think they are turning out nicely. Any tips before I wrap up the wing build?
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Old Jun 27, 2012, 03:35 PM
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Looks good so far. If the instructions don't specify otherwise, I would glue in the dihedral braces before adding the top center sheeting.
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Old Jun 27, 2012, 09:38 PM
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Cool!

Thanks for starting this thread, now I get to see one of these being built and see how it all goes together so I can take notes. I've thought about getting one of these for a calm day slow floater and still thinking about it. First I need to finish my modified Spirit project.

Adios - Paul
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Old Jun 28, 2012, 06:20 AM
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Hi Fickle,

Our club just built five of these for a one design event.

FWIW each one had trouble with the 1/16" leading edge sheeting in the kit. It was very brittle and very easy to break. In some cases the sheeting was paper thin.

Paul, our experience has been that this plane can handle a fair amount of wind, 12-15 mph worth.

Don
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Old Jun 28, 2012, 11:38 AM
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If the 2M flies anything like the 100",you'll love it.

I just flew my Sig Riser 100 for it's maiden flight. I stretched the wings to 112" and built a Pod and Boom fuselage with build up tail feathers.

I wasn't sure how well it was going to fly. Or if it would fly at all But it is now one of my favorite planes. What a great flying,floating plane. I love mine.

I'm sure you'll love the 2M also.
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Old Jun 28, 2012, 11:41 PM
Making wood fly since 2007
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Fickle,

It's nice to see another Riser being built. I built mine 4 years ago and I still enjoy it. I built mine just like the plan called for and only made two modifications. The first was I added spoilers and the second was I built the rudder without the balance tab. Now having flown it for 4 seasons let me tell you what I would do if I built it again.
  • I would probably take off the balance tab again, it's a visual thing for me not performance. But, if you do that you would be wise to make the rudder a little bigger to make up for the lost area.
  • A notorious weak spot on this plane is the elevator, specifically the wood piece which holds the two elevator halves together. Reinforce this area either with a stronger piece of wood or maybe a carbon rod if you happen to have one. A little fiberglass CAed onto the joint would work also. Worst case scenario is the two halves break apart but the plane will fly just fine with half an elevator. Trust me on this one.
  • Get the servos placed as far forward as you can get them. The plan shows them further back then they need to be. This plane will require nose weight and the more gear you can get forward the less dead weight you will need to add.
  • When you put the top sheeting onto the fuselage face the open end where the wing TE will hit it with a little light plywood. What happens is that the wing TE will ding up the top sheeting there and that will make it hard to maintain proper wing alignment.
  • Shorten the hatch cover by about an inch and glue that section to the fuselage at the wing LE. This gives the wing a solid forward point to rest against and that will also help keep the wing aligned.
  • To assist in getting the upper wing sheeting to bend to the curve of the wing lightly dampen the top part of the sheeting with water and a sponge. Don't soak the wood because you only want one side of the wood wet. This will cause the wood fibers on that side to swell and it will bend/curve the wood for you. This should allow you to get it glued down and held in place while the glue dries without splintering it.
  • Be sure to run the servo rods along the fuselage sides and not down the middle of the fuselage. This makes it much easier secure the rods and prevent slop in the pushrods. It also makes it easier to install ballast later on should you want to add some weight on windier days because the center of the fuselage is open

That's all I can think of right now. Enjoy your build.

Wayne
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Last edited by Windependence; Jun 28, 2012 at 11:49 PM.
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Old Jun 29, 2012, 03:50 AM
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Don't pin through stressed wood like the spar caps! If you haven't glued it in yet, turn it around and put the pin hole towards the outboard end. If you don't have all the spar wood picked out, use the wood with the straightest and closest grain on the top inboard sections, the next best on the bottom inboard sections, and the rest on the tip sections. If it all looks the same, put the heaviest wood on that top inner spar cap, and so on. With the heavy end inboard.

If the grain on the spar caps is more than just a little crooked, replace it. You can use spruce(especially sitka) or fir (especially douglas), but look for tight, straight grain. Lots of other woods can work but they must be at least as strong as what comes with the kit.

If you see crooked grain elsewhere in the kit, don't be afraid to replace that wood as well.

Maybe the above isn't necessary, but I haven't built a Sig kit in years. Even on a high quality kit (which I know Sig used to be), it's a good idea to double check the wood.

In general, be aware of which balsa seems heaviest and stiffest. Use that wood toward the front and on highly stressed areas, and use the lighter stuff toward the back and on low stressed areas. For instance, the elevator can be made of pretty light stuff, especially if it's the correct type of grain.

For balsa that will be bent across the grain, A-grain is best and C-grain is worst. On the other hand, c-grain is great for stuff you don't want to bend across the grain. So it would make a good elevator.

Some useful pictures for identifying type of grain here:
http://sigmfg.com/cgi-bin/dpsmart.ex...FV5.html?E+Sig

Slow glue=low blood pressure. I prefer carpenter's yellow glue such as Titebond and to work on some other assembly while the one I just did dries. With a bit of planning, it won't slow you down, and you can reposition parts if they get put down in the wrong place. At least for the first few minutes. Also, it won't irritate your nose and lungs. Of course, high stress areas that don't fit VERY tightly should get epoxy.

Leaving off the balance tab probably does NOT mean that you need to make the fin and rudder larger, as long as you extend the top of the fin to replace it. That tab is not very efficient and causes lots of drag. Also, the rudder will be stronger if you leave the tab off.

It's a personal choice, but I don't like to Monokote fully sheeted surfaces like the fuselage. I prefer something like Sig Sanding Sealer, carefully applied water based urethane (damp paper towel, many applications), etc. You might want to put a bit of epoxy and glass on the bottom of the nose, as there's lots of abrasion there.

If the kit doesn't have it, be sure to reinforce the trailing edge where the rubber bands go. This can be as simple as snipping an aluminum rectangle out of the trailing edge and gluing it on.

If you have wood working tools, and you're going to need lots of noseweight, you can take some maple or something and make a new nose block. Much harder to work, but because it's extra far forward, you won't need as much extra weight. Check that it isn't too heavy before gluing it on. You can also hollow out the back of the block a little and glue in weight.

A more robust joiner is to take some music wire (not any old wire, but music wire, which is very strong) , maybe one sixteenth, and bend it so it can go along the inboard edge of one elevator, across the middle and along the inner edge of the other elevator. Maybe .047" would be stiff enough, I'm not sure. Don't count on the glue to hold it, but wrap something over it. Maybe a little cotton or fiberglass cloth glued over it or something like that.
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Old Jun 29, 2012, 04:11 AM
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Thank you for the help

This is exactly what I was hoping for. Thank you for the replys. I will look into most of these mods.

The spoilers are already planned. I will have to look closer to understand the rest of the modifications. I am really green and some of this stuff is just totally over my head.

Also, thanks for the wood selection tips. Everyone always talks about it but I don't really understand it beyond buying a scale to weigh it I have done virtually no selection at all.

nice 100 BTW. I actually called Sig to change my order to a 100 and they had already sent the 2 m out (within 4 or 5 hours really nice people and great service). Anyway I had been going back an forth on the convenience verses my perception of performance. That said I am happy I have the 2m for the moment (maybe I will need both).

More to come I am making super small gains as I have some work stuff that gets time consuming at the end of the month.
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Old Jun 29, 2012, 04:14 PM
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Here is a build thread from 2009. Very nice build, with some modifications: http://www.rcgroups.com/forums/showthread.php?t=1119189
But that's a 100. Maybe you can find some inspiration?

Here is mine Sig Riser 100. It's not really a slow floater. But maybe the Riser is more of a floater. Mine is kind of fast flying.
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Old Jun 29, 2012, 09:35 PM
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My 2 Cents.............

Fickle Flyer-
1st- I'll going along with everything everyone else already mentioned, they're right and have good methodology.
2nd- I don't want to toot my horn too loudly, but scroll through my build log the "Great Planes Spirit 2M with Modifications" (or however I titled it), look at how I used yellow glue and a iron approx 200-ish degrees to apply sheeting to the wings and other things, you'll be able to do this with your spar caps. This will be my 4th build, so I'm not any "expert" but I'm applying everything I've learned from the first three gliders and from people here on RCgroups such as the guys who have already put their 2cents in here also.

I'm not anti-(your favorite adhesive here that's not yellow glue), but I'm VERY PRO-Alphatic resin Yellow Wood Glue. If carefully fitted, almost everything if not everything can be applied with it, even fiberglass cloth, however, I yield to 20min finish epoxy on that. A LOT of low strain applications of fiberglass can instead be achieved with yellow glue and wetted cotton cloth(one or more layers), yes, really, it's surprisinly robust, less messy and nontoxic.

Speaking of fiberglass, I'm VERY PRO fiberglassing the nose of your plane, especially if you're new to flying, flying gliders with no motor, etc. It will be structural weight in front of the center of gravity which means less BB's added to the nose later(in other words, it really won't be adding any weight since you'll be adding it later anyway) and it will be keeping your plane together better during suboptimal landings.

Hope that is of some use to you.

Adios - Paul
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Old Jun 30, 2012, 01:29 AM
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Quote:
Speaking of fiberglass, I'm VERY PRO fiberglassing the nose of your plane, especially if you're new to flying, flying gliders with no motor, etc. It will be structural weight in front of the center of gravity which means less BB's added to the nose later(in other words, it really won't be adding any weight since you'll be adding it later anyway) and it will be keeping your plane together better during suboptimal landings
Word! I have glassed some models. It's not difficult, and it give the extra strength the Riser need. I glassed from the nose, to just aft of the wings. And of course fiber glass on the middle of the wings, where the rubber band goes.
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Old Jul 01, 2012, 09:52 AM
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Haven't been working on the build as I am busy at work (I plan to build a bit this weekend). I did cut a bunch of the parts and weigh some stuff. So far my inboard wings are off by 2 grams. That said I have a leading edge piece that is over 7 grams heavier than the rest of the pieces generally around 8-10 grams. I was thinking of just puting it on the inboard wing so it would be 5 grams off as I thought it would have less effect closer in. The other option is to see if I can get another piece today at the LHS. I am going to check it out.

For now I have been cutting the pieces for the outboard wings. I thought maybe one will come out much lighter than the other and I can use the heavy piece there. This leads me to a question. How much difference in the sides is acceptable (weight difference) from wing to wing.

Also, a few other questions while I am at it. Does anyone know of any good instruction sites about fiberglass application? I haven't looked into it at all.

Also, curious if elmers wood glue is the same as tightbond or is tightbond a lot better? I have elmers already is the only reason I ask.

Is there a better way to hold stuff together for drying or are pins the way to go?

Thank you
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Old Jul 03, 2012, 08:34 PM
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Not specific to model aircraft, but you may find this useful:
http://www.systemthree.com/reslibrar...Epoxy_Book.pdf
For flying models, you want to blot out any excess epoxy. You can do this with toilet paper and just a little pressure. Some people use a roller. The epoxy that's in between the fibers does most of the work, and anything pooling on top adds weight without helping very much.

The leading edge is a good place for dense wood, as it hits things first. If you were going to get another piece, I'd suggest matching the heavy leading edge, at least inboard. But I bet, unless the other pieces are light and soft, you can just use what you have. I don't know exactly how much imbalance becomes important, but I think it's probably more than what you are seeing.

If your Elmer's wood glue is fairly fresh, it's good. If it's getting thick, toss it. It's very similar to Titebond, though there are now different formulas with various forms of water resistance, and even a gel. I haven't played with the gel much, but don't try to fill gaps with it! Joints must be tight fitting with any of these glues. The gel might be handy for keeping the glue from running off vertical surfaces before you join them. I agree with Paul that it is good stuff. Just don't let it freeze or sit around too long. (Maybe a year or two, longer if larger container?) White Elmer's glue, on the other hand, seems to have a much longer shelf life. I've done indoor models with it but I'm not sure how good it is with denser wood. I have a pennyplane built with imitation Elmer's white glue that is holding together since the '80s. I suspect the white stuff is pretty good, but I don't know in what ways it's different from the yellow stuff. All of these have almost no odor and are supposed to be non toxic. That's nice, especially when working indoors.

I've used the heat activated yellow wood glue trick (with Elmer's, I think) to stick down sheeting. I have a glider I built that way around 1990, that has crashed a few times, but the sheeting stays put. I applied the glue to the ribs, put the sheeting in place, removed it and cleaned off any globs of glue. After the glue was dry I ironed the sheeting back on.

I've also used the Elmer's and cotton cloth trick. Works nicely on a quick and dirty winding stooge (for free flight models) I made years ago.

Pins are fine for holding stuff together. For denser wood or more critical joints, clamp if you can. For laminating something like doublers and fuselage sides, put the pieces on a flat surface and apply lots of weight. You could put down a sheet of upholstery foam or foam rubber from packaging, and then put on lots of magazines, books, etc. Be sure to wipe off any extra glue and to put plastic wrap or baking parchment under and over the pieces so they don't get glued to the board or the foam. If you have a vacuum pump, this is a great place to use it, but you don't actually have to go overboard. You could use a garbage bag, some paper towels to let the air out, and a vacuum cleaner. At least if you could stand the noise for an hour and the vacuum didn't overheat. Or this might be a good place to use the dried on glue and iron trick if you can keep it nice and smooth so there are no voids.

Some people like to use magnets and a steel building board surface.
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