First lighting of the fires RCGF-USA Stinger 20cc

Today I made a few adjustments to the tank plumbing, as I accidentally reversed the fuel fill and the vent lines. Realized that when I started to fill the tank and fuel,started running out the vent as quick as it went in. Took the plane out for her first start and run.

On opening the basement doors, ran into this little guy working on his nest. He stood there and wondered if he should run, or if I would leave. He took off. If I didn't come and go this would be a great nest spot.

Started right up! Took a few minutes to find her feet and as each minute passed she ran better and more smoothly.  Tweaked the needles a bit, but a smidge only. Within a couple minutes of running it quit when the spark wire came off, melted and cut right thru the plastic wire tie. Came up with and actual wire system to hold it (below).

Got even more smooth than this.

I ran a stranded wire around the spark wire, and used a copper tube crimp to close the loop. As I noted earlier the cowl will also support it. I then threw another plastic wire tie around it again, using some shrink tube to protect it from heat and friction.

The finger nuts came in, so I can now secure the cowl. I am placing a rubber bonded washer to reduce the likelihood it will not work loose from the vibration.

I balanced the 15x7x3 Master Airscrew. I expect the 3 blad aluminum spinner in a week, but for now I do have a black DuBro spinner I can use to check CG shortly.

She is a wish away from maiden.

Nitroplanes Pitss Model 12 Build Basically Done!

 

Installed the fuel dot.

The sparky isn't  securely, but is firmly sticking to the plug, and I am afraid to force it, so am using this zip tie to keep it from loosening off. This and the cowl will hold it in place. Its not tight, just holding it. 

Finally on all her wheels!

Installed the lower wing without any drama.

Break in prop on!

Top wing on for fit testing!

Fuel vent installed. Tougher cote around it.

Fuel tank did arrive today and installed, plumbed and ready to go!

I made these wires for the cabanes and they look great. I am willing to install the til wires but its not as obvious to me where they go. Back to the web for ideas.

Next step will be firing up the engine! Hope my transmitter comes back soon.

Nitroplanes Pitts Model 12 20cc Nearly Done!

I haven't posted for a few days, but I have been busy. An unexpected delay in the arrival of the fuel tank had to be worked around, it should arrive tomorrow. Here are some updates. Things went really well.

Combo shot of the aileron and its control horn, the servo hardpoint. The wing side had to be expanded to allow the servo to fit, hence the carve outs. There were a few weaknesses in the design that required this sort of fix. The standard servo barely fit on the cover/hardpoint.

 

The top wing.

The elevator halves are joined by a balsa "rod" between the halves. I wanted some more stiffness across the halves since the servo is attached to the port side (see below) and drives both elevator sides. I put a steel rod I bent into shape across the cross over, and this worked as designed. 

This is the starboard side. Not shown is that I went on to double the control horn putting another one over the existing horn. When I drilled a larger hole for the larger control rod, the margins around the hole were much less than desired. This strengthened the control horn and the connection.

This is the port side with the servo. The elevator and rudder are the 25 kg torque version of the 20kg ones on the ailerons. I really like the quality of these servos. The control rod provided were way too long, so I used this Traxxas one I had laying around as it was perfect. It uses an M3 bolt, hence needing to drill out the control horn. Sturdy undies to be sure. Also here is the rudder pull-pull connection.

Installed the RCGF-USA 20cc Engine. I love this engine!  Its like it was made for this airplane, fits perfect with no modification. 

The throttle servo set up I had to rig. Works well. My notations on the rail mark the WOT, middle and stop throttle positions I used to set mid throttle on the servo. I had to make the opening smaller for the servo so it would secure correctly.

One of those design issues. The cowl bolt heads are inside the cowl, I don’t have a hex screw driver long enough. Also, the way the cowl is set on it has to come up from underneath a bit and gets pushed up into place, so this really is the only way. I need to figure something out.

Perfect center. You can see the cowl mount bolts inside the upper right and left sides. Putting s 2.5 inch aluminum 3 blade spinner over the Master Airscrew 15x7x3 prop, after breaking it in with a MA Scimitar 2 blade.

The rudder pull-pull system.

The underside of the lower wing, the center of which is where I laid down the fiberglass  under the AMA sticker. Came out nicely. Painted the control rods flat black, the stock white was just wrong.

The big M4F sparky doesn't hold onto the RCExcel ignition spark plug wire (neither does the CM6 I tried). I  set up the cowl cut-outs to allow part of the cowl to hold it in place.

The  cowl cut-outs for the muffler pipes and the tip of the spark plug wire. 

Painted the aft part flat black.

Internal electronics layout, the battery not in place. Spektrum AR637T receiver, Tech Aero UBEC that filters noise from the ignition nd is the ignition on-off switch, the flag-pun powerswitch, the rudder servo. Underneath is the voltage regulator taking the 7.4V battery packmdown to 6.6V.

The underside, above the wing. Wiring and the voltage regulator.

The Ignition LED and the flag-pin fail-on reciever power switch.  Works perfectly! Wonder how long before I snap the pin off...

The backside of the flag-pin switch. I added some support to the fuselage balsa to support use of the switch. Battery pack. Imhad to search for some time before I found this flag-and-pin fail-on switch at RadicalRC, one designed to not to need a power regulator system, but to act as  primary switch. 

Very clean electronics bay. Missing the fuel tank still. It will be mounted to the port side forward of the receiver. One antenna horizontal, one vertical.

Tech Aero UBEC lateral to the 2S 7.4V 5200 mAh LiPO battery pack.

The RCGF-USA Stinger Engines sticker, one on each side. 

Thanks Joe at RCGF-USA! I add the weblink.

Tomorrow the fuel tank will arrive. I need to solve the cowl bolt problem.

 

Nitroplanes Pitts Model 12 20cc Build Continues

The joy continues!  The past couple of days have seen some progress. Here's some work over the pat couple of days.

 

Put the wheel struts on. These babies are some sturdy underpants. The kit comes with some really good quality upper fairings that are made of fiberglass. I wish the Phoenix Waco had come with something like these. There's some rubber tubing to use along their edges. More on that when I install them.

Sorta on her legs. Won't put the wheels and pants on for now.

This is the Pitts next to the 20cc Phoenix Waco. When the cowling goes on she will be several inches longer.

I permanently joined the lower wing halves.

On an aside I painted the tips of the Master Airscrew 15x7x3 prop I have on hand. This is the same one I use on the PulseXT with its 20cc engine. 

Aileron servos are all on their hardpoints ready to install. These generic servos are really amazing quality.

I didn't do this with the Waco, but the YouTube video of the Pitts with a 20cc engine shows the canopy popping off despite the latch. This suggests there is some kinda internal air pressure, so I decided to put a exit vent on the back underside. I had one from a previous build hanging around.

With that "popping off of the canopy" I also wanted to add a couple strong magnets to help secure it.

That's them in the corner. 

I don't have a lot of faith in wings joined with a short wood beam rather than a wing tube, because one of my PulseXT 40's folded like a diaper pulling out of an easy loop. Since then any design with that I tend to want to put a couple layers of thin fiberglass on the underside. I peeled back the cote, taped it off, sanded it (there was an epoxy sine from the joining seen here).

Sanded smooth.

I used 15 min epoxy thinned with alcohol, painted the wood with it, laid down a sheet of fiberglass cloth, layered it with more epoxy, laid the second sheet, and more epoxy. Smoothed it out.

 Letting it dry. Once it's dry enough I will cut the edges clean and pull the tape, let it dry a day or two, then cote it after a light sanding.

This is the fine fiberglass cloth I used. It is kinda hard to work with in that it un-weaves with even the slightest traction.

Today the RCGF-USA 20cc engine arrived today! I am expecting the ZYHobby fuel tank, and the rudder and elevator servos to arrive today as well, along with the voltage regulator, so I hope to make some progress. It will be a few days before the flag-and-pin switch arrives.