Calendar year 1999 was dedicated to research, development, design, performance and testing. We evaluated three of the leading brands of airframes, three leading models of engines being offered, three leading manufactures of chutes, and three leading manufacturers of propellers. After endless hours of flying and studying all configurations of frames, chutes, engines and propellers we went to work on our first prototype.
The goal was to design an airframe that was simple, clean, and strong with emphasis on detail. The first and most obvious improvement was to run the chromoly frame rails the entire length of the airframe, giving a strong structure for mounting your engine and suspension. The rear end of a PPC is what takes the abuse of time, abuse from engine and propeller vibration, not to mention those not so perfect landings that in a lesser design will destroy a propeller.
The next design enhancement was to reduce the number of junctions, nuts & bolts that were inherent in the existing PPC’s airframes and most noticeable in the engine and fan guard area of these designs. Powrachute threw out the tiny channel brackets, plastic saddles and multiple tubes found in the existing designs and replaced them with single piece radiused engine support tubes, formed 6061T6 Aluminum extruded brackets and precision machined 6061T6 Aluminum saddles.
The next improvement was to plug every tube. We noticed that this was only being done in structural areas of other PPC’s, therefore without a plug if a bolt was tightened too much the tube would egg shape and cause fatiguing of the tube. In addition, holes in the frame that do not have plugs will eventually elongate the radius of the drilled hole. By plugging “every” tube and using precision machined saddles you eliminate this problem. Each plug
is machined .0005 over, shrunk in -400F nitrogen then installed. The plug then becomes an intrigal part of the tube sealing out any moisture for future corrosion issues.
Another improvement was the design of our one piece A-arm suspension. This piece was cleverly designed. Before the bend of the A-arm takes place we drive a 3” piece of 6061T6 Aluminum bar stock to the center of the axle bolt hole. This makes a solid connection point for the wheel. Once this is driven into place the tube is then bent to form the A-arm. You will notice the A-arm is attached to the chromoly main frame in a manner that allows it to move freely in an up and down motion, working in concert with the hydraulic spring over shock or the upgraded air adjustable shocks.
Now let’s take a look at the fan guard area. On most designs you will notice use of brackets, bolts, rivets, etc to join the hoop ring to the fan guard supports arms. Although this is effective it is not the most simple or clean application. On all Powrachute designs you will notice a very simple clean application in this area. By utilizing liquid nitrogen we are able to freeze and shrink the plugs that are used on the fan guard support arms where they attach to the ring. Once the plug comes back to room temperature it expands and locks into place. The saddles we use to join the tubes and the fan guard supports to ring have a machined recess on the flat side of the saddle for the fan guard support to join into the saddle providing a smooth clean finish. To complete the junction you will notice another saddle and a 3 ½ stainless lag screw that screws right into the plug that was sweated into the fan guard support.
The frontal fuselage bars are another Powrachute innovation. This design feature was scoffed at by our competitors as unnecessary and if you look around now you will see most manufacturers now offer them standard or as an option. The reason we added the frontal fuselage bar was to provide an added measure of protection to the pilot and passenger in the event they should fly into an object such as a power line, fence, tree limb, etc. Two by
products come from the use of these bars. (1) Added roll over protection (2) the trussing of the frame from the pylon to the nose wheel. This is one innovation we were actually happy to see our competitors copy, providing their customers with this added measure of safety.
Why does Powrachute use a bolt together frame versus a welded frame? The short answer is that we build aircraft not race cars or motorcycles.
Keeping the above statement in mind we make maximum use of certified component parts in our design. AN Hardware is certified military specification hardware and has with stood the test of time. 6061 T6 also falls in the class of aircraft grade aluminum. A welded frame is only as good as the person doing the welding and even the best welders when welding certified parts should have them x-rayed or magniflux tested. Additionally, if you have the best welder and x-ray the welds, it would be difficult when pre-flighting your aircraft to find a cracked weld caused from the stresses put on the airframe after several hours of flight time. Another reason we use a bolt together is to make it easy to replace damaged parts. If you damage a welded frame you will have to locate a fabricator or become one yourself to make even minor repairs. How do you paint it to match the factory powdercoat job? In other words we don’t believe a welded frame is as fail safe as a bolt together frame.
Why doesn’t Powrachute build a lighter aircraft? We could and it would be simple to produce and lower cost to produce. We choose not to because we don’t like the tradeoffs that come with this decision. To do so would mean sacrificing structural integrity of the airframe something we are not willing to do. Consulting with the two leading parachute design engineers in our country, Bill Gargano of Quantum Parachutes and John LeBlanc of Performance Design, we started development and testing of the high narrow attach system. After doing multiple flights at different spread distance we found a winner. We discovered exactly what Bill and John had told us, better performance! Better in flight stability, rocking common with the low wide spread is significantly reduced with the Pegasus. The traditional stair step climb is all but eliminated, turning performance is un-matched. You may be asking yourself why this higher more narrow attach can accomplish such a significant improvement over the traditional low and wide set-up. I’ll do my best to explain.
The core engineering in the parachutes design came from the sky diving world. If you look at sky diver’s chute, you will notice it is attached to the shoulder area which is high and narrow. You see, the traditional low and wide outrigger gives the parachute more leverage on the cart in addition the low position causes the lifting point to be right through the center of mass. This causes the cart to pitch up and down in a rocking motion when hit with a gust of wind from the front or rear. When hit with a side gust the chute lifts the cart from a low wide point on the craft causing a bucking and yawing effect. By utilizing the high more narrow attach we have not eliminated but have significantly reduced these effects.
You might be saying ok that makes sense but what about this better climb rate. I have to admit that this was not anticipated but was discovered in flight testing. First of all by utilizing the high attach we were able to get the lifting point significantly higher than the thrust line, which allows the cart to push out in front of the chute quicker, changing the angle of attack of the chute sooner creating a shorter take off roll once your chute is kited over head. Some designs actually have the thrust line above the attach point, causing the thrust line to actually push the cart in down and forward direction creating a longer take off roll, slower climb and a more pronounced stair step climb.
The other effect we learned was that the higher more narrow attach had the ability to minimize the traditional stair step climb associated with low, wide attach points. In a full power climb with the low wide outrigger you will notice once the cart gets to its peak angle of climb the chute rotates back over the cart, then the cart gets back in front again and so on, during the climb. With the high more narrow attach point you will notice a steadier straight climb angle. You will notice the Pegasus is still climbing while others are stepping.
Do your own research and you will find the Airwolf and Pegasus are simply the best powered parachutes money can buy.