SIG Riser 130 rebuild - Page 3 - RC Groups
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Jan 01, 2011, 09:12 PM
Registered User
flyb0y's Avatar

Theory for what it's worth

Hey PP

I've retired my Riser, and am scrambling to get my Oly III done before spring, but thought I'd add a few comments about theory, as I understand it.

If the Riser design at 100 inches is ideal, then adding more wing means that your elevator and rudder moments (ability to turn, pitch) will be lacking. In other words with a larger wing you will need to do one of 2 things, extend the fuse to give the elevator & rudder greater leverage or increase their size. How much ... that I can't tell you ... wish I could, I simply know that increasing the size of the wing will increase it's pitching moment and require more force to hold its angle of attack (stab), and additional rudder force to turn the bigger wing.

I'm still learning the degree to which the ideal (theory) applies to the reality of flying, but I don't think it can be ignored.

Good luck! Let me (us) know how it turns out

Last edited by flyb0y; Jan 02, 2011 at 09:41 AM. Reason: fixed a bit of miss-speak ;)
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Jan 01, 2011, 10:08 PM
planepainter's Avatar
Hi Joe. Good comments. I am going to use a carbon boom for the fuse to get that tail feathers back further. And I will most likely rebuild the tail feathers anyway as the old ones won't mount to the tail saddle as they are. I would still like to make them removable somehow. A lot of interesting challenges.

Jan 02, 2011, 04:27 PM
planepainter's Avatar
I am at the point on the wing where I will begin to add the flap arrangment. I have one question though. What should the trailing edge/ flap attach material be? Balsa or spruce? It has to carry some strength so I want to get it right. Thanks.

Jan 02, 2011, 06:53 PM
who has rabbit ears down
Captain Canardly's Avatar
PP! I'd go with 1/8" spruce for the falspar, and D Stackhouse was discussing shear web loads @ the Raven site, so I think I'm gonna start doing flap LE's with 45 degree balsa plys- 1/4" total- sounds pretty impressive way to get strength and rigidity!
Jan 05, 2011, 11:39 PM
Thermal Naked!
Hossfly72's Avatar
Hi Hoss,

That's a really good idea. Why didn't I think of that ????

Bob in Seattle
Cause you're not as lazy as me Bob! LOL
Jan 06, 2011, 08:46 AM
planepainter's Avatar

gap strips

Quote: Hey PP,

What about just sticking some 1/16th cap strips on top of the ribs to meet the new sheeting. Sure the wing will be a little thicker, but you'll have less sag between ribs and it's not really a speed demon anyway so the thickness won't hurt much.


Hoss, I am not the brightest bulb on the christmas tree so I am not quite sure what you mean by "gap strips" and where they go.

Jan 06, 2011, 11:15 AM
registered weapon
CAP STRIP: 1/16'' balsa strip 3/16'' wide or so that run the length of the rib, top and bottom, between the d-sheeting and trailing edge.

thread is about carbon cap strip but 1/16'' balsa would be sufficient in your case &just what your looking for to solve your question
Last edited by IHAVAWDY; Jan 06, 2011 at 11:39 AM.
Jan 06, 2011, 11:54 AM
Thermal Naked!
Hossfly72's Avatar
IHAVAWDY got it PP. I figured it would be easier than sanding the sheeting down to perfectly match the ribs all along the wing. Basically, it would just be increasing the height of the rib up to match the sheeting and it would keep the covering from sagging a bit. My Sagitta 600 has cap strips so they just popped into my head.
Jan 06, 2011, 12:20 PM
registered weapon
Last edited by IHAVAWDY; Jan 06, 2011 at 10:48 PM.
Jan 07, 2011, 12:19 AM
Registered User
I think you may be overdoing it with the flaps. On lots of thermal duration gliders the l.e. of the flap is just foam. That's not ideal, but it takes quite a while to fall apart. If you want to use spruce, a good place is the last bit of the flap trailing edge. Plane it to match the taper of the rest of the flap. T.e. is much stronger that way.
Jan 09, 2011, 11:05 AM
planepainter's Avatar

flap construction

Hi guys. Still working as often as I can on the project. My wife is in the hospital with MS so I am gone a lot. But I find that working on my sailplanes during this hard time gives me seasons comfort.

The first photo shows that I have cut the top and bottom pieces for the flaps. I considered using trailing edge material but found that the pieces were not straight enough and rather than try to straighten them, I decided to build the flaps. Besides, I also wanted the flaps bit deeper than the trailing edge material would afford.

After measuring for the depth of the flap and then for the trailing edge stringer, I trimmed the ribs and glued the stringer in place making sure it was perfectly flat with the rest of the wing.
After securing the top and bottom flap pieces I used CA to drop in some carefully cut flap ribs. These ribs will give support the flaps and also provide proper spacing. Sorry about the photo but I too it too close.

Jan 09, 2011, 12:59 PM
planepainter's Avatar

gluing front strip

This photo shows that I am now gluing the front strip into place. This small, long piece goes along the front of the flap completing the last of three sides. This will butt up against the trailing edge stringer.
Jan 09, 2011, 05:43 PM
volare est vivere
ray foley's Avatar
hi there from Toledo

Hey PP:

What kind of clamps are those in the last photo? You sure have a scad of them.

ciao -rjf

ps: My club is "the Flying Tigers R/C Airplane Club" and we may need some of those dandy P-40 shirts. How about some up to date info on them so I can take the info to the club officers?


Ray Foley
Jan 09, 2011, 07:19 PM
planepainter's Avatar
Hi Ray. Those are just metal hair clips that you can buy at any Wal Mart or Drug store. They are very affordable and can clamp lightly when bigger clamps might do damage. The nice thing about them is that you can bend the tips slightly to match different shapes.

I PMd you about t-shirts.

Jan 10, 2011, 09:58 AM
planepainter's Avatar

flap installed

This photo shows the completed flap installed with a piece of tape on the bottom which is the way I plan to hinge it.


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