DonStegall

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Next on my lay-up list is the Swee' Pea.

I have one on hand that was primed in the mold. But it does not have carbon fiber in the nose or tail and I have someone wanting one with the CF.

I have molds for the tail and wing, but I'm going to make templates for foam cores. The original wing was only 52", but I'm going to stretch it out to 56".

The original plans also have a ventral fin option that mimics one version of the real Swee' Pea.

DonStegall

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I've had some interest in the Swee' Pea lately. I snapped off a pic last night and one this morning with my mock up wing. I am getting back into full production of the composite Swee' Pea kit. As well as a fiberglass and foam version. The fiberglass and foam kit is $125 plus S&H. I will post the composite kit price soon.

DonStegall

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I'm making a couple of molded composite Swee' Pea airframes.

I laid up another wing today. Here are some pictures I snapped as I was doing it. I might try to notate the pictures later.

PylonDave

Wow Don, it looks like you are setup for production!!!

DonStegall

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Dave,

I'm lucky to have a big work area. I designed my house and I designed a 37'x20' room with a 10' ceiling in it upstairs. And I negotiated with the contractor for my Dad to be able to work onsite and he added a 23'x13'x8' room as well. I'll shoot some pictures. It takes a lot of room to do composite wings without having to shuffle stuff around. That's one of the reasons why I recommend that people start out with small pieces like V-tails before they graduate to wings.

Templates are essential to making composite parts and enjoying the process. Just like building a regular plane, you need plans. I make templates for every part that is repeatable. Here are the templates for:

1) the wing skins
2) the wing cloth
3) the wing peel-ply and breather

DonStegall

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And I do have a lot of space. I have a number of 6'x2.5' tables and some other tables.

BTW, I have a new name for the business. It is [link=http://HouseOfPylon.com]HouseOfPylon.com[/link] and it now takes you to www.StegallHobbies.com ... I have not started changing the web site yet. What do you think of the new name?. I think it is more representative of what I do.

These are pictures of the perimeter of the shop.

DonStegall

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Here are pictures of the interior of the main shop.

Note that you don't see a lot of planes and parts sitting around. Most everything lives in the other room on shelves. The other room has the table for vacuum bagging wings and tables for vacuum bagging tails and smallers parts.

DonStegall

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The skins came out fine. I let them stay under vacuum for over 36 hours. I was too tired last night to do a tail anyway.

Here are a couple of pics

DonStegall

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I used to make the Swee' Pea wings from 3/32" balsa. I used 1.4 ounce cloth on the outside and 0.7 ounce on the inside. The problem was that the trailing edge is hard to do with the thick skins and the complex curves of the tips don't always lay down unless you use soft contest balsa. So I decided to switch to 1/16" skins. I'm using 1.4 ounce cloth inside and outside.

This change requires a whole new set of templates for the internal structure. The internal structure consists of the spar, ribs, blocks for the front wing hold down bolts, and pieces in front and behind the hinge line.

I've got to cut some cores and sheet a couple of wings today, but making the structure and closing this wing is my priority for the next two days. Since I don't have any CAD drawings of the wing, I have to use mechanical methods to make the templates for the structure. As I will be creating documentation, it only takes a little extra time to post here, so I'm going to post pictures and words. That way you and my customer can see how I do the work.

DonStegall

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Because of the frame on the top mold, I can't drill the torque rod holes from the bottom side. So I made a jig to drill them from the top. It is indexed on the nearest two clamping holes.

DonStegall

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Reference lines are drawn for the ribs and the spar end location.

Then a profile gauge is used to get the shape of the root and tip locations so that the spar size can be determined.

The spar size is critical. If it is oversize, the wing will not close properly. Either the seams will be too thick, or they won't be sealed. If the spar is undersized too much, a lot of extra glue will be required and that adds weight in a hurry.

I drew the root and tip sections. The root measured just over 0.8". With 1/16" skins plus the cloth, this sounds about right since the wing should be close to 1". I have a fiberglass mockup wing and I will check it from the outside to see just what the maximum thickness is at the root..

DonStegall

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Here is the reference wing.

The root measured 0.990" and the internal measurement is 0.815". The tip thick point measured 0.510" and the internal measurement is 0.375". The tip difference is just over 1/8" inch which is to be expected for 1/16" skins. However the root difference is 0.175". After looking at my drawings I realized that the Cf laminate is at the thick point of the root, but not at the tip. So that adds about .020". I still have .050" unaccounted for. I have to look at the skins to see if maybe they don't exactly conform to the molds in the center section. I think the top has a bit of a fillet in the center section and that may be part of it.

What I will do is the first rib position which is 1.5" out and see how it compares inside to outside.

DonStegall

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Using the profile gauge, I created drawings for the ribs. You can see the gap at the rear of each rib, this is where the glue will fill in the gap. I will work on reducing this and making the skins come closer to the edges so that less glue is needed for the edge join. But for now, I need to get the wings made.

DonStegall

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I made the template for the spar. I reduced the size by .050" to allow for .014" carbon laminate top and bottom and .020" of gap. That will be pushing it in terms of size, but I think the balsa skins would compress enough if it is oversize by a few thousandths. Plus when I make the balsa spars I will make sure they are not oversize at all.

I made spar material out of a piece of 3/8" x 4" x 48" contest balsa. It weighed 3.7 ounces. I cut it into 8" pieces and glued it with TiteBond yeilding a 24" x 8" piece. This should make spars for at least 6 wings.

While the glue is drying I'm going to cut cores and sheet a couple of wings. So I have to move the spar material off of my cutting table.

DonStegall

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Here are the spars and the CF laminate before assembly.

Epoxy and cabosil was mixed up and put on the spars. Then the CF laminate was placed on the spars and they were put in presses.

They'll be ready tomorrow.

DonStegall

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The spars came out fine and the measurements are good. One tips is about .260" and that is .010" over what I wanted, but my measurements were based on pen marks and the profile gauge, so I'm not going to worry about it.

Here's a picture of the spar on the wing.

Oh, the weight of the spar was not bad. 1.1 ounces total. The breakdown is that the wood for each half weighed 0.2 ounces and the CF for each half weighed 0.2 ounces. So I only used a little over 0.1 ounces of glue per side.

DonStegall

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Making the torque rods is the next step. The ribs have to go in, but they have to be fitted and the torque rods notched into place. So here is how the torque rods are made.

I use 1/8" [link=http://www.houseofpylon.com/Materials/TorqueRods.aspx]Torque Rod Material[/link] which is welding rod. The rod I use is pristine with no blemishes to cause problems with the bushings.

I make a bend which is 1.5" in this case. It is important to make the bend before cutting the threads so you don't scar up the rod.

Then the rod is cut to length.

Using a [link=http://www.houseofpylon.com/Tools/DieStock.aspx]1" Die Stock[/link] holding a [link=http://www.houseofpylon.com/Tools/Die6-32.aspx]6-32 Die[/link], threads are cut on the torque rod. The torque rod is held in a vise using a rubber pad to prevent any scarring of the surface.

DonStegall

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The completed torque rod. A 5" long piece of 5/32" aluminum tubing is used as a bushing. The torque rod extends several inches into the aileron as it costs little in weight.

Note that two ribs will have to be notched for the torque rod.

The torque rods are heavy because they are steel. At 0.6 ounces each, they contribute to the weight. But you have to have reliable control. And these are absolutely solid with no solder joints, collars, or screws to come loose.

I think I'm going to start offering these pre-made for my Quickie 500 sheeted wings.

DonStegall

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Here is the top of the wing with all of the structure in place. Everything is glued down except the spar. The ribs were CA'd in place as were the pieces in front and behind the hinge line. These pieces seal the wing from air entering from the hinge. The torque rod bushings are just tacked down with CA to keep them from shifting during the join.

Don't know if I'll have time to take any pictures of the glue. If I can, I will. I have to fill the edges, and then put it on the structure, and finally run a bead around the edge. This is the part of the process that makes a wing usable or a piece of trash.

DonStegall

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I did manage to get one photo of the glue.

The wing cooked in the hotbox at 80-95 degrees for 12 hours. Then I let it cool for 1/2 an hour.

I took it out and it looks good. No surface blemishes.

The untrimmed weight is 17.7 ounces and I think it will go below 17 after trimming because some of the leading edge glue is in the overhang.

DonStegall

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The finished wing came in at 16.9 ounces. It is very strong. The hinges came out just right. They have a lot of movement, but are still very stable. The Kevlar was just the right amount.

DonStegall

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Here's a picture of the production tail and wing on an older fuselage. I'm laying up one with carbon fiber in the nose and tail this afternoon.

PylonDave

So Don from the pics it looks like you have 3 strips of kevlar on each airloin + what ever fiberglass is on the top of the wing???. The carbon on the airloins is on the top of the airloin but does is not part of the hinge right??

DonStegall

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Dave,

The wing skins are 1/16" balsa. I used 1.4 ounce cloth inside and outside. So the hinge has two layers of 1.4 ounce. Then the three pieces of Kevlar. I cut the middle piece sort of in half, but Iwill probably just use a 1" piece from now on.

The carbon fiber tissue is 0.5 ounce and it is only on the part of the aileron outside of the hinge area. I extended it past the balsa so it would strengthen the area where only cloth and glue make up the sharp trailing edge. There is CF tissue on the top skin and the bottom skin. Iuse tissue because cloth is too thick, and laminate doesn't conform to the curves of the beveling of the balsa. Plus the random fibers strengthen the aileron in all directions. At the front of the aiileron there is a piece of 1/16" balsa (during the join). That's all the gap there is. That's a major reason I switched to 1/16"skins from 3/32". It was too hard to get the skins shaped properly. And the 1/16"skins are plenty strong with the 1.4 ounce on the inside.

Now I'm ready to put this plane in production and the initial kit price will be only $275 for the molded composite and $360 for a Ready To Paint with the tail jig mounted and engine mount / firewall installed.

DonStegall

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I have a new jig in progress for mounting the tail. I will take pictures when I'm satisfied with the design.

Doing threads this detailed is a little bit of extra work. I hear from some people who follow them. Do you like the threads? Have I done enough that it's time to just do my work and stop posting? I do know that my customer for this plane has enjoyed seeing the process. So that is probably enough to justify doing them. Just wondering about the rest of you.