This is the plane currently under development. I call it the "Wedge" (I had to call it something) due to it's very angular shape. A simple plane in both concept and design, this is the ninth in the series. Some have been a nominal .40 size although the last few have been a nominal .60 size. Eventually, the design will be carried into much larger planes; the ZDZ 80 twin should make an excellent power plant for a Wedge in the 18 to 20 lb. range.
The concept of the Wedge grew out of the need to make a highly aerobatic plane that was very inexpensive and quick to build. Learning 3D, especially the hover, can take a lot of planes. I started with Morris designs (the Knife is still the best overall 3D plane available commercially) but found that they are too expensive to buy over and over again. After building two Morris planes, it became quite obvious that these would be very easy planes to scratch build. The next step was to make a bigger version powered with a Saito .91; this is the plane that I actually learned to hover with. Finally, I began to "work backwards" with interesting results- instead of trying to alter / improve existing designs and concepts, I wondered what would be the absolute minimum needed to make a workable plane. The result is the Wedge; I do not believe it can be lightened or simplified much further no matter what materials are used.
The idea is very simple- use the minimum amount of material needed to attain a given area and / or shape. The wing is easy enough.... just follow the design of the lightest available wings made today. The ailerons and tail feathers are also quite conventional. The fuse, wing and engine mount took a little more effort but again, it's nothing more than a stolen idea. For centuries it has been known that the lightest, strongest structure type is truss construction- look at any railroad bridge as an example. Most people seem to think that the fuse design is complicated and 'engineered' but this is not the case; it was designed 'on the fly' using the "that looks about right" system!
To make the plane easy to construct, all sub-sections are nothing but trusses built flat on a building board. The fuse shape occurs at assembly and is actually quite easy to do. Final alignment is done using straight edges and sightings (looking straight down the structure).
This is what the fuse sub-sections look like before assembly.
The nose sections are also built flat.
The sections are then joined to form the fuselage. This is the rear fuse assembly before the nose is attached. The vertical wood just to the left of the glue bottle is where the fuse will eventually separate for transportation but during assembly it is left as one piece.
This is the forward part of the fuse now joined to the rear portion. The engine mounting portion is at the extreme right. Scraps of wood are used to hold the entire assembly together while it's aligned and the wing is fitted. Pictures of the wing are not shown here because it is a very conventional "D" tube design. The wing area is clearly visible in this picture although the vertical support has not yet been removed.
After the wing is installed and the fuse itself is rigidly and permanently mounted, the lite ply nose plates are added. These provide the necessary strength to tie the engine, wing, fuse and landing gear together. In this view the rear of the fuse has been removed.
After having quite a few conventional shear webs fail due to glue-line delamination, I've been using this method with great success. Again, a truss design with 3/32" balsa end plates to increase the contact area of the crossed sticks. Not quite as fast to build as shear webs but as light and much, much stronger.
Side view. Note the vertical attachment point on the fuse and the tongue & groove retainers (only the top connector is visible in this view).
This is what it looks like taken apart for transport. Only (2) 1/4-20 nylon bolts are used to assemble the plane. Both attachment points are made of 1/8 lite ply and 1/4 plywood for the tongue itself. This arrangement has not failed yet and appears to be strong enough to take the greatest flying abuse imaginable.
All electrical connections are incorporated into the bottom attachment point. This is the back, or male half. The near three connections are for the rudder and they are redundant; each wire uses (2) electrical contacts in the event one fails. The elevator connections use only one contact each but as there are (2) separate elevators and elevator servos anyway, a measure of redundancy is built in. NOTE: So there is no misunderstanding, the "male" part of the connection refers to the mechanical connection only. It just so happens that the "female" electrical connector is mounted to the "male" mechanical connector; this <could> cause some confusion.
This is the front-bottom, female connector. Again, it's the mechanical female connector and obviously the male electrical connector.
This is the completed, flying plane. Note that there is no vertical stabilizer- this too appears to be an unnecessary part used on most aircraft.
Coating is laminating film- similar to hobby coatings but cheaper, lighter and in my opinion, easier to work with. Power is provided by a YS .91 AC engine. The two aluminum pieces on the upper / front fuse are fuel dots. The landing gear is 3/16" music wire. And yes, the wheels are home-made :-)
It may not appear so in this picture but the fuse is just slightly under 12" from top to bottom at it's widest point. Wing span is 51". Wing area is 1,000 sq. in. and side area is 500 sq. in..
All-up weight is 5 lb. 12 oz.. Vertical is..... impressive.
In the hover, the fuel tank is clearly visible as is fuel quantity. A nice touch but purely and totally accidental (it's a by-product of using clear covering).
The hinges are also somewhat unusual. They are "X" or rolling hinges made of the covering material itself. Two strips of coating are cut, one is inverted and the glue sides are ironed together in the center. This strip is then cut into strips about 3/4" wide. One side is ironed onto the stationary part (wing, horizontal stab., etc.) and the other side is ironed onto the flight surface (aileron, elevator, etc.). The strips are alternated from top to bottom and crossed as they are attached. This creates a hinge that resembles the letter "X" when viewed from the side. The advantages to this type of hinge are: No wood cutting necessary, absolutely no gap needed and absolutely no friction as the surface is deflected. Also, they allow a full 90 degree per side deflection.
My goal was to arrive at a final design eventually but it seems that this many never happen. Several modifications have been made since these pictures were taken including new aluminum motor mounts (to ease assembly and be both lighter and stronger than the original maple bearer beams), a new aileron design to allow better airflow over the tail when the ailerons are deflected (coupled ailerons- "flaperons") and a modified, split elevator using a pair of servos. This has had several advantages including greater potential deflection, redundancy in the event of an elevator servo or elevator control failure, and "ailevators" which allows the elevator halves to move synchronously with the ailerons and yields much better low speed roll control. As time passes, more ideas occur and these often end up on the plane itself. Not all have been steps forward though; there was the unfortunate incident involving a much too far rearward placement of the aileron and elevator hinges. It <seemed> like a good idea at the time but turned out to be awful.
This picture is of the latest generation Wedge, taken as my brother 'catches' it. Note the smoke trail coming from the plane and moving toward the right- there was a pretty stiff breeze blowing from the left, hence the angle of the plane. This photo was taken at the South County R/C Club's annual display put on at the URI Balloon Festival on 29 July, 2001. This particular plane has all the latest improvements including a redesigned wing (both airfoil and construction), no aircraft plywood used anywhere, no hardwood used anywhere, and aluminum motor mounting plates. And before anyone asks, no, we did not call each other and color-coordinate before going to the 'Fest but it did seem to work out that way :-)
