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I decided to put a better GPS in my P2K GPS installation. The "standard" GPS for Light installations is the Sparrow. The little white box has the GPS receiver built in then the usual two servo connections, Transmitter connection and pressure sensor connection. It is enough to do things but since I normally fly the bigger stuff, the Sparrow is really annoying. It is a 4hz GPS RX and it takes a few minutes to sync up with the satellites. You also have to be more careful on the turns with the slow update rate.
The Sparrow is nicer but you have to deal with the external GPS RX. So there is more gear to install. I also wanted to put the TEK probe on the P2K. It makes no sense to pipe things to the tail on a small model. Instead I decided to install the V-tail probe behind the wing. It has to be removable and it also has to be far enough back to clear the ballast rod in the fuselage. That bar extends a good inch behind the wing. The tubing also has to be carefully placed. There is a rectangular guide for the bar under the center of the wing. The tubing has to be outside of that and the bar can't run into it in the back. The probe also ends up in the area you sometimes exit the RX antennas on a P2K because the RX fits under the back of the wing.
To solve the probe mount problem, I built a brass tubing elbow by soldering one tube into another. Note the bottom of the vertical tube is filled with solder to seal it up. I glued a small block near the top and fished the mount through the fuselage hole below the RX area. Double and triple check the ballast rod fits and you can fish the tubing in with glue applied. The photo shows the brass and tubing and where it needs to exit the fuselage behind the wing.
The next part is the Swift, and GPS antenna install. I made a tray that inserts in the front of the fuselage boom part. It fits just above the ballast rod. The Swift slides into the boom right at the wing LE. This is a carbon area, but that is OK. The GPS RX then sits on top of the ply plate so it is sitting in the fiberglass pod part of the fuselage. The TEK tubing also ends around there and a piece of flexible tubing is used to make the 180 bend back up to the top of the fuselage. The pressure sensor is just stuffed in alongside the Swift. The GPS RX coax is cut down to 15cm. Probably should have done about 13cm.
The photo shows the general layout. There is no space in a P2K fuselage especially under the wing. The ballast rod is there, servos and RX are flat above that. And pushrods are along the sides. It is a pain to cut and install those pushrods.
The RF for the Swift sits on the bottom of the fuselage. The short 7wire cable just makes it there. To keep the TX wire straight, I cut a strip of 1/64th plywood and tape the antenna to the plywood. This way the wire stays straight when you slide in the battery. The wire on the bottom below the battery works just fine. The only time I get no RF is when the model is sitting on the ground.
The other cabling problem is all the wires up front. I had to connect the motor/ESC channel which provides power, the servo/power connection to the Swift and I wanted the telemetry input to my RX so I could get flight pack voltage normally, and full power and current telemetry with my Unisense when I want to test props and motors. The ESC power wires are 24 guage, motor control signal is 26 guage, for the telemetry and Swift, the power wires are 26 guage and control line is 28 guage. This is teflon coated silver plate wire and it all fits in a 1/8 heat shrink tubing to keep it bundled.
The RX case got stripped. I ran the antennas out the top just in front of the TE They end up several inches behind the wing.
Motor is an XPower Windy 2925/8 with a GM 11x8 prop and YGE 65LVTE controller. Peak current is over 60A on 3S but it drops down to around 50A. It might be a little toasty on runs in a really hot place. The pack is a 2200mah battery. This is really generous. I have done two climbs and at least one full 20 minute course using about 1000mah. So two climbs is very safe, I can probably do three full flights without landing. The YGE controller is pricey but it has a good, adjustable voltage regulator and the telemetry is configurable for a bunch of different radios incuding JR DMSS. Also nice and thin. The XPower outrunner in a can is just nice and inexpensive with plenty of power. Currently I am flying this a little more nose heavy than my P2K's I fly in thermal contests but there is room for cutting the pod to shorten it and move the CG back.
The Sparrow is nicer but you have to deal with the external GPS RX. So there is more gear to install. I also wanted to put the TEK probe on the P2K. It makes no sense to pipe things to the tail on a small model. Instead I decided to install the V-tail probe behind the wing. It has to be removable and it also has to be far enough back to clear the ballast rod in the fuselage. That bar extends a good inch behind the wing. The tubing also has to be carefully placed. There is a rectangular guide for the bar under the center of the wing. The tubing has to be outside of that and the bar can't run into it in the back. The probe also ends up in the area you sometimes exit the RX antennas on a P2K because the RX fits under the back of the wing.
To solve the probe mount problem, I built a brass tubing elbow by soldering one tube into another. Note the bottom of the vertical tube is filled with solder to seal it up. I glued a small block near the top and fished the mount through the fuselage hole below the RX area. Double and triple check the ballast rod fits and you can fish the tubing in with glue applied. The photo shows the brass and tubing and where it needs to exit the fuselage behind the wing.
The next part is the Swift, and GPS antenna install. I made a tray that inserts in the front of the fuselage boom part. It fits just above the ballast rod. The Swift slides into the boom right at the wing LE. This is a carbon area, but that is OK. The GPS RX then sits on top of the ply plate so it is sitting in the fiberglass pod part of the fuselage. The TEK tubing also ends around there and a piece of flexible tubing is used to make the 180 bend back up to the top of the fuselage. The pressure sensor is just stuffed in alongside the Swift. The GPS RX coax is cut down to 15cm. Probably should have done about 13cm.
The photo shows the general layout. There is no space in a P2K fuselage especially under the wing. The ballast rod is there, servos and RX are flat above that. And pushrods are along the sides. It is a pain to cut and install those pushrods.
The RF for the Swift sits on the bottom of the fuselage. The short 7wire cable just makes it there. To keep the TX wire straight, I cut a strip of 1/64th plywood and tape the antenna to the plywood. This way the wire stays straight when you slide in the battery. The wire on the bottom below the battery works just fine. The only time I get no RF is when the model is sitting on the ground.
The other cabling problem is all the wires up front. I had to connect the motor/ESC channel which provides power, the servo/power connection to the Swift and I wanted the telemetry input to my RX so I could get flight pack voltage normally, and full power and current telemetry with my Unisense when I want to test props and motors. The ESC power wires are 24 guage, motor control signal is 26 guage, for the telemetry and Swift, the power wires are 26 guage and control line is 28 guage. This is teflon coated silver plate wire and it all fits in a 1/8 heat shrink tubing to keep it bundled.
The RX case got stripped. I ran the antennas out the top just in front of the TE They end up several inches behind the wing.
Motor is an XPower Windy 2925/8 with a GM 11x8 prop and YGE 65LVTE controller. Peak current is over 60A on 3S but it drops down to around 50A. It might be a little toasty on runs in a really hot place. The pack is a 2200mah battery. This is really generous. I have done two climbs and at least one full 20 minute course using about 1000mah. So two climbs is very safe, I can probably do three full flights without landing. The YGE controller is pricey but it has a good, adjustable voltage regulator and the telemetry is configurable for a bunch of different radios incuding JR DMSS. Also nice and thin. The XPower outrunner in a can is just nice and inexpensive with plenty of power. Currently I am flying this a little more nose heavy than my P2K's I fly in thermal contests but there is room for cutting the pod to shorten it and move the CG back.
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