DonStegall

My Feedback: (1)

The Viper 500 wing is a good wing. The only real problems with it are the weight and the ailerons. The weight can be anywhere from 18 to 19.5 ounces out of the box. And the ailerons having only a 1" chord have resulted in many people losing control as they get slow on landing. The weight is more of an issue for the clubs running Quickie 25 as many have adopted a 3 pound 4 ounce minimum weight limit.

I'm going to attempt to build a better wing for the Viper and other planes that use the S8064 airfoil. I will keep a close eye on weight and strength. This wing will not be as strong as a Viper 500 wing. But it should be up to Quickie 25 and AMA 424.

I'm going to start with my Light wing. This wing has .007" x 1" carbon fiber laminate on top and .007" x .75" on bottom with fiberglass on the trailing edge. It also has 1/64" plywood on the trailing edge. Because I am using contest balsa, I have made the decision to start using at least 36" of 1/2 ounce to 3/4 ounce fiberglass between the skins and the cores. On the S8064 wings I am using cloth between the entire surface of the balsa and foam.

With this wing all trimmed up, except for the last bit of trailing edge, the weight is 9.5 ounces. It needs a leading edge. Even though I cut the cores for a 3/16" LE, I am going to put 1/4" on it just in case I sanded down or trimmed down any little bit too far.

djlyon

I've never cut a Viper wing up, but why is the wing you are building not as strong, or 428 strong. Other than some center section glassing and a good leading edge before finishing it looks strong enough to me. I do build stronger myself but I overbuild.

Denis

DonStegall

My Feedback: (1)

Denis,

It may be. It doesn't have much more flex now than a Viper wing does and it's not even covered yet. I think if it is glassed on the outside it will be as strong. The Viper 500 wing has wood spars in it though.

I didn't use a carbon fiber leading edge on this one because they are adding up to an ounce to the wings. At least before they are sanded down.

DonStegall

My Feedback: (1)

I didn't have any 1/4" x 1/2" x 48" balsa, so I cut some from a 6" sheet. It weighed 1/2 an ounce. It is well oversize, so the main addition in weight will be the glue.

I mixed up a batch of WEST 105/206 and added cabosil to it. I spread it on the front of the wing and put the leading edge in place with tape on the ends and in the middle. I then scraped away the excess. Then I added more tape. With the tape and all, it was up to 10.4 ounces. It will have to cure overnight, but I'm doing multiple building tasks tonight, so time is not an issue. A good cure of the epoxy is more important.

DonStegall

My Feedback: (1)

The next step is to rough trim the leading edge to shape.

A lot of people wonder how I get as much done as I do. It's not that I work fast. it's that I have tricks that I use. Masking tape is one of my best friends. To rough shape the leading edge, I place 2" masking tape on the skins to protect them. You've got to remove a lot of material and the contest balsa skins are so soft, you will spend a lot of time trying to sand down to the skins without hurting them. The masking tape solves the problem.

Use a plane to rough the leading edge to shape. Say within 1/16" of the skins. Then I use a 12" sanding bar with 80 grit paper. The 80 grit cuts quickly and the 12" is managable. If you see masking tape getting scuffed, back off on that area.

I rough trimmed this leading edge in less than 30 minutes.

Oh, the weight is now 10.0 ounces. So the leading edge not fully shaped has added only 1/2 an ounce.

But It's 9am and I have to go to "work" now.

DonStegall

My Feedback: (1)

The next step, if you haven't done it from a previous wing is to make sanding templates.

I include a printout of the airfoil with all of my cores and sheeted wings. I am going to get laser cut templates, but I just got set up with SIG as a manufacturer, and the lead time is several weeks plus I have to get the CAD files together. So we'll do it this way for now.

Our main focus is the leading edge template, but it is easier to just go ahead and lay out all of the templates now, even if you don't cut them until you need them.

Part out a leading edge template, a trailing edge, a top, and a bottom.

Cut out a piece of 1/8" light ply. I suppose you could use 1/8" to 3/16" balsa, and then harden up the edges with CA.

Spray 3M 77 on the ply and on the backs of the templates and put them together. You don't want the paper coming off.

After this dries, I will cut out the leading edge template and start sanding the leading edge to shape.

DonStegall

My Feedback: (1)

I cut out the leading edge template tonight. I realized I need to send 2 copies of the template, or else you need to get one or more copies made. The reason being that you need to be able to check yourself as you sand out the template.

I used a Dremel scroll saw and cut it pretty close. Then used a half round file and a 1/8" round file to get it to shape. I also found out real quick that you need to mark top and bottom. I've only done symmetrical 66-012 wings in the past and that wasn't an issue. I put my template on a Viper wing and panicked when it didn't come close to fitting ... upside down.

So now the task of shaping the leading edge begins. One thing to remember is that if you mess up, you can always cut it off and glue another one back on.

Electric Delta

My Feedback: (13)

I like to use Perma-Grit sanding blocks for shaping leading edges, among other things. They are very straight, very long-wearing, and have 80 grit on the one side and 120 grit on the other. After doing the basic shaping with the plane, and two stages of Perma-Grit, I then switch over to a padded sanding block, just to smooth the surface up with 220 grit or so paper, not really changing the contour much any more. Good enough for film-covering. Of all the tools in my shop, the Perma-Grit sanding tools are the ones I couldn't do without.

freeair

i must say the viper 500 wing is abit on the heavy side considering its a covered wing and not painted but i will say as for ailerons are concerned , there is no need to enlarge there size just for the sake of safer landings. i have found this model to be a very predictal with both power on and power off, the aileron size is perfect and if more was added so would extra drag be added resulting in slightly slower speeds in turns etc , if the pilot has trouble in there landing approaches with dead stick [ no power ] all thats needed is the use of dual rates on ailerons, so instead of the normal aileron rates set at say 1/8 th inch up and down , hit the dual rates so its 1/4 inch up and down.