Last weekend I started on the airframe modification to the Stryker for the speed competition. The first step was to smooth out some lines on the front end of the plane. There are some cosmetic air intakes along each side of the canopy. The fronts of the intakes are flat and have a significant impact to the orthographic projection of surface area for drag. I took my handy wire cutter and streamlined the profile freehand. Some final forming was done using a medium grit sand paper. The imperfections were then filled with a lightweight spackle and sanded to a smooth finish. The overall area reduction is not huge, but at speeds in excess of 100 miles per hour, it will have an impact.
The standard Stryker has 4 cavities in the foam at each training edge to accommodate the elevon tabs. Since I am making custom elevons out of balsa (with control hinges), I filled the cavities with spackle as well. Once filled, the training edge was sanded smooth.
During the modification I added a 6mm carbon tube to the underside of the wing. The spar was set into the foam using my hot wire cutter and epoxied in place. The position of the spar is just aft of the servo pockets, extending from wing tip to wing tip. I have see some discussion in regards to reinforcing this airframe with additional pieces of carbon, but it is my belief that with a fiberglass surface there is more than enough strength in this airframe.
With the spar epoxied in place, I sanded the entire surface of the airframe to remove any molding imperfections in the foam. I then wiped all surfaces with denatured alcohol to prepare the surface for glassing.
Last night I began the glassing process on the bottom of the airframe. Using a .75 oz fiberglass cloth, I cut out a single piece that would cover the entire bottom surface. I then mixed some water-based polyurethane with a small amount of water. This was done to prolong the dry time of the PU, so I could work the surface smooth. With the glass laid in place, I worked the PU over the surface and into the weave. I started the application at the fuselage, and worked my way out to the wing tips. With the surface whetted, I used a business card to squeegee the excess PU for an overall smooth surface. With the PU drying, I took an exacto knife and trimmed the leading edge of the wing. I then went back and applied more PU along the edge to verify that the glass was secure.
Pictures to be added soon…
Thursday, January 28, 2010
Friday, January 22, 2010
Flying Videos
In addition to the modified F-27 Stryker I am building for the speed competition with Andy, I also build a Parkzone Super Cub over the Christmas holiday. This is not your standard cub, and definitely not a trainer anymore.
• Turnigy 35-36c motor turning APC 11x8e, 54 AMP ESC, and 3S 2200mAh 30C battery
• Covered with Econocote
• Added ailerons
• Zero dihedral wing with 6mm rod reinforcement
I received a small HD camera for my birthday, and have been recording some of the flying done this winter. I will have some video up of the cub in the next day, or so. I have been having some issues with some new video editing software (Adobe Premiere Elements 8), but I don't want to get started on that issue.
Here is my version of a WW2 Navy J-3 Cub. Yes, I took some artistic license with the design.
• Turnigy 35-36c motor turning APC 11x8e, 54 AMP ESC, and 3S 2200mAh 30C battery
• Covered with Econocote
• Added ailerons
• Zero dihedral wing with 6mm rod reinforcement
I received a small HD camera for my birthday, and have been recording some of the flying done this winter. I will have some video up of the cub in the next day, or so. I have been having some issues with some new video editing software (Adobe Premiere Elements 8), but I don't want to get started on that issue.
Here is my version of a WW2 Navy J-3 Cub. Yes, I took some artistic license with the design.
Thursday, January 21, 2010
Throwing Down The Gauntlet
THE CHALLENGE
Winters are long in Minnesota and we all need to find things to keep sane. Over the summer I started flying RC airplanes with a buddy of mine. As winter approached we were discussing builds that would keep us busy. As the discussions progressed, the tone turned more competitive. An RC speed competition, where the only rules are that the plane must use electric power, and must continue flying after the top speed run has been captured.
The prize is for nothing more than the honor of building the fastest plane, but I plan on creating some sort of traveling trophy for the winner to hold until the next challenge. The competition will take place some time in early March, but a firm date has not been set.
THE BUILD
My initial build plan was to create a mid-body pusher YF-22. I had some initial models created, but was worried that the amount of design work would keep me from meeting the March deadline. I started to focus on commercially available foam airframes that others have already modified for speed, and had a proven flight envelope. The final decision was to go with the Parkzone F-27 Stryker airframe. It's cheap, it has good slow flight characteristics, and it has been modified to fly at speeds of 130+ mph. http://www.youtube.com/watch?v=gSM2kAYxIx4
STATUS
At this point I have all the components to start the modifications to the airframe. Specific details regarding those modifications will be outlined in the coming days. At this point I am sanding the body smooth of all molding imperfections and surface defects. After the sanding is complete, there will be some information regarding reinforcement of the airframe. Unfortunately this work can not be complete until I receive the motors from Hong Kong. Stay tuned...
Winters are long in Minnesota and we all need to find things to keep sane. Over the summer I started flying RC airplanes with a buddy of mine. As winter approached we were discussing builds that would keep us busy. As the discussions progressed, the tone turned more competitive. An RC speed competition, where the only rules are that the plane must use electric power, and must continue flying after the top speed run has been captured.
The prize is for nothing more than the honor of building the fastest plane, but I plan on creating some sort of traveling trophy for the winner to hold until the next challenge. The competition will take place some time in early March, but a firm date has not been set.
THE BUILD
My initial build plan was to create a mid-body pusher YF-22. I had some initial models created, but was worried that the amount of design work would keep me from meeting the March deadline. I started to focus on commercially available foam airframes that others have already modified for speed, and had a proven flight envelope. The final decision was to go with the Parkzone F-27 Stryker airframe. It's cheap, it has good slow flight characteristics, and it has been modified to fly at speeds of 130+ mph. http://www.youtube.com/watch?v=gSM2kAYxIx4
STATUS
At this point I have all the components to start the modifications to the airframe. Specific details regarding those modifications will be outlined in the coming days. At this point I am sanding the body smooth of all molding imperfections and surface defects. After the sanding is complete, there will be some information regarding reinforcement of the airframe. Unfortunately this work can not be complete until I receive the motors from Hong Kong. Stay tuned...
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