Need some pics of different ways to build take apart wings. Thanks for the help. Guy

A quick primer on take apart wings

I apologize for not having the time to flesh this out more fully at the moment but I will edit it as time permits.


Building a take apart wing is no different than building a one piece wing. You will proceed in exactly the same manner. It is importent to consider that the only thing you are doing is replacing the balsa spar material and the sheeting immediately on top of it at the point where you cut through the spar. For the most part, sheeting on a wing does not add to the strength of the wing (with respect to its ability to carry a load) (it helps transfer loads) in any location other than at the high point of the wing (yes it helps provides torsional resistance for the panel itself but we are only interested in attaching the wing to the fuselage) so cutting the sheeting does not present a problem. In order for the wing to fail, the high point would have to fail first. Since that is where the spar is, if it failed then there is no other major load bearing structure in the wing and hence the wing would fail. Most full size wings are stand alone units which attach at only three points per panel, at the high point of the main/carry-through spar (upper and lower) and at the drag/rear spar. The drag spar is there so that inertial forces do not cause the wing to pivot forward as the plane halts its forward movement. So all we have to do is make up for cutting the spar and the sheeting directly above it with our mechanical fastenings. Since we are going to replace balsa wood with aluminum we don't need very much metal.

It is also no more difficult to build a take apart wing than to build a one piece one. If you have the requisite take apart fasteners, I would say that it would add only about an hour of building time to the project. You can of course make the prcocess more eleborate but it is not essential.

The take apart pieces are boltled together as if the wing were assembled and then glued as a unit to the main spar with epoxy (24 hour). In most cases you will need to either box the metal pieces in with balsa or bind them to the spar with strong nylon thread (or both). Once the epoxy dries (depending on what else you may wish to do to the wing) you can cut the spar and unbolt the wing panels.

Below I have attached some pictures of different take apart systems and construction details.



The first four images show the wing take apart pieces of the SkyWriter. You will note that the bolt (sometime refered to as the "Jesus Bolt") is in shear. This is by far the prefered way to make a take apart but it also reqires some fairly exact milling. Most take apart fasteners will have the bolt in tension. ( I have never had one let go)

Note that the spar itself is made of maple. The aluminum pieces are epoxied and pinned with brass rod. The maple main spar has sweep built in and is also a machined piece. (Maple machines very well!) Notice the vertical end grain bracing between the spars. The spars must not be allowed to move towards each other or the wing will fail at once.

Take apart wings part three: One piece wings


I would like to show you three different methods of making a one piece take apart wing. We will look at a full built up fuselage with no pipe, a profile fuselage and a full built up fuselage with a pipe. Since I just took apart "Classic" we can look at how this goes together (or comes apart  :-)  )

To make a one piece take apart wing for a piped model, we need to provide a means to attach the wing at both the leading and trailing edges to the fuselage. As opposed to a full fuselage plane without a pipe tunnel, we will need to move the actual joiners up (towards the top of the fuselage) in the fuselage so that they do not interfere with the installation of the pipe. The front attachment will made via a doubled former at the leading edge of the wing. The rear attachment is by means of a plywood tab that projects past the trailing edge of the wing and mates up to horizontal former in the fuselage.

When you are building the fuelage, position a doubled former at the leading edge of the wing. To make this former cut all pieces and make up two square plywood formers just slight larger than is required. Then tack glue the two formers together and using something like a miter-sander sand them perfectly square. Without taking them apart, lay out the fuselage/fuel tank compartment rear former and the wing leading edge former. The fuselage former is full depth as in a normal model terminating just below the area where the pipe passes through. The wing former will run from the centerline of the wing down to the same point as the fuselage former. (see the first three pictures)

The first picture shows the former at the rear of the tank compartment (looking aft) with three aluminum bushings to accept the 4/40 bolts that will hold the front of the wing. The second picture shows the same former from the rear (in the space where the wing will go). The third picture shows the front of the wing and the duplicate former with three blind nuts to receive the bolts. Note that these formers must be made of plywood.

Note also the triangular blocking in the tank compartment. The complete take apart system was installed prior to making the bottom of the pipe tunnel.

The next picture shows the pipe tunnel looking aft and the rear attachment point.

It should be noted that before any take apart pieces were installed, the wing was temporaily installed and attached to the lower section of fuselage running below it. The take apart fastenings were then built around and up to the existing structure. Once all attachments were made the rest of the pipe tunnel was fabricated. Finally,the lower fuselage sides were cut free from the rest of the fuselage.

The next picture shows a close-up of the rear mounting point. Note the larger plywood plate in the picture is attached to the fuselage with 1/2" triangular bracing on the top side. (not visible) Also note the two aluminum bushings fro the 4/40 attachment bolts. Both the plate that attches to the wing and the one that attaches to the fuselage were fabricated first and the bolted together. A wedge of balsa was carefully fabricated to position the wing joiner plate exactly horizontal and both pieces were then glued to the wing and fuselage at the same time. It is irrelevant if the joiner is mounted crooked as the wing is still mounted perfectly square to the fuselage at this point. (it sounds harder than it is) The reason for the small step is to accomodate the pipe mount at a lower point so the pipe would lay horizontal without needing to make the fuelage deeper.

Next is a front view of the former at the wing leading edge. Note the three blind nuts to recieve the attachment bolts. Also note that the triangular pattern of the bolts permits the center section of the former to be relieved to permit the pipe to pass through.

We now see a top view of the rear mounting plate projecting past the trailing edge of the wing and actually inside the basic fuselage box as well. Note the traingular bracing to help attach the wing to the fuselage sides.

Next is a picture of the rear mouning point in the fuselage. It consists of a plywood plate that is also glued inside the basic fuselage box. The fuselage plate is suported by 1/2" traingular stock on the top side.

Next we have the completed lower fuselage and pipe tunnel below the wing. All take apart pieces were comletely installed and functional before the lower fuselage  under the wing was cut apart from the rest. Then the pipe tunnel was fabricated.

The next picture shows both the front and rear fuselage mounting points and the space where the wing sits. A saddle is made by using expoxolite forced into the crack between the fuselage side and the wing while making the filet. DO not make this filet with non structural fillers. You need the strength of real epoxolite in this area.You will note that the fuselage sides near the canopy are fairly shallow. 1/64" ply was used on both sides to stiffen this up and prevent cracking. (The plane is now five years old and shows no signs of fatigue)

The next to last picture is out of order but shows more of the detail of the rear wing joiner including the balsa block to make the wing joiner plate level.

The final picture shows the completely assembled wing and fuselage.


.........more pictures and more editing to com.........

The plywood facings are attached to both the center section and the wing panel. There are four pieces of 1/64" ply in the photo, two glued face to face along their periphery on each side. The plywood is laid out perfectly square and center lines are applied. Holes for the take apart fixtures are drilled. The outer rib of the center section and the outer rib of the wing panel are aligned to the center line of the plywood rectangle and glued in place. The plywood is then positioned in the cradle between the two foam pieces. The ribs will come to rest on the foam as if they were not attached to the plywood. You now install the spars and sheet up to each plywood piece and sheet the center section. Once trimmed of the overhanging plywood the take apart spar holes are opened up through the balsa and the bolts are removed. (The bolts remain captive in the take apart fitting so they won't get lost)  Assuming no glue has made it past the edge of the ribs, the wings will fall apart.


Kim.

Guy,

No SHOCKWAVE is a wholly new design from the gound up made just for electric power. It is 740 square inches in area and has almost unlimited power. The SkyWriter is 620 square inches and was powered by a conventional .60.


p.s. more pics and info posted.

Neville,

The primary reason we use take apart technology is to enable the model to be packed into as small a case as is possible. Generally the tube in the fuselage sticks out quite some distance either side of the fuselage. R/C planes generaly have their servos located in the wing right at the aileron or flap. Any flexing of the wing at fuselage due to imperfect fits of the two tubes is mostly irrelevant. Control line planes have their flap actuating device permanently installed in the fuselage thus if the wing were to flex due to the take apart mechanism you would disturb the centerlines of the flap horn and the flaps themselves. Next, take a look at the total weight of the take apart system used in SHOCKWAVE, only 40 grams!. Lastly, the tube would need to go right where the bellcrank is usually installed in the fuselage and might impact the routing of the leadouts inside the wing. I am sure it can be done your way but why mess with success.

The technology described is not complex at all. Like I stated in the posts above, it adds only a bit of work to the construction of the wing.


Kim.