After a lot of troubleshooting yesterday we concluded that the culprit was in fact the compression collet prop adapter. HUGE shoutout to Craig at Horizon Hobby as I was able to finally meet up with him and he had the proper bolt-on adapter. I removed the cowl and dummy radial and used my dremel with a cutoff disc and hacked off the end of the motor shaft for the new one to fit. The prop seats further rearward with this adapter so I cut of a bit of the dummy motor dome. Full power on and I have no more vibration.
Had another flight late yesterday afternoon. Perfect flight. No issues. I flew without the additional pack for ballast and there was little change in behavior. It was about a 4 minute flight and my packs came down with 3.75v per cell. I think I’d like a larger pack for at least another minute of flight. I’ll also note that the shorter flight may be due to the prop I’m using. I’m considering a Xoar WWII prop as I love Xoar props but the lighter weight will probably help with flight time. The trade off is the sound. I just love the sound these MA classic props make.
After doing some cleanup in the shop and doing some battery maintenance, I dug out the telemmetry files to have a deeper dive into some data because, well, it's me.
The graph below shows the RSSI signal strength from two flights. In blue is a flight on the P-47. The orange is on a Sundowner 50, which is a balsa aircraft as well but it does not have any aluminum. Both aircraft are using the same X-series receivers from FrSky. The only difference being 2 channels... X6R and X8R. They use the same protocol and antennas. The other factor is the distance. The P-47 was flown twice as far away from me over the Sundowner. The data shows that there is a difference of around 10% lower signal on the P-47. However, the RSSI low warning is at 20% signal. So we are WELL above that and that is with flying it at quite an extreme distance. The field at SEFF is enormous and I was at the far east end of the flightline. I was told on this flight that I had crossed past the far west end of the runway on this flight. THis is a full scale size runway. It is FAR. The Sundowner was kept within the east half of the runway. I want to note that this data directly correlates with a study on 2.4Ghz systems (Futaba and Spektrum) back in 2007 by a group of guys over at Flite Metal. There is a loss of signal on aircraft with aluminum, but it is not nearly as dramatic as you may think.
Ok, I got a new prop in the mail yesterday. I've been an advocate for Xoar props for a long time now. Look at the picture and you will be gin to see why. These props are the SAME size... 16x8. The MAS is WIDE and beefy. I put these on the scale and the MAS prop weighs in at 103 grams and the Xoar weighs in at 45 grams! The smaller amount of rotational mass will likely help me in my maneuverability as well as efficiency and throttle response. Some yellow on the tips and I think I'll be good.
While I had the prop nut off I took the opportunity to polish it up. Boy I'm glad I did. It matches the rest of the airplane much better now.
The last thing I need to touch on is damage a damage report. While there were a few wrinkles here and there the extent of damage from the trip is minimal. However, there is one spot in particular that needs some help. I used the hook side of a strip of velcro to stick a portion of microfiber cloth to the strap and then go over the airplane to hold it down. Apparently the single layer of cloth was not enough to prevent the tiny hooks from digging into the aluminum. I've worked out these with my burnishing tool for the most part but I'll likely never get this perfect again. Some spots need to be re-polished but that should not be a big deal. Maybe a half hour or so of work and she will be sparkling again like new.
I took the Jug out to the field this weekend. I wanted to see how the landing gear would handle my home field. Of course the Eflite gear handled things just fine. I also ran up the new prop and it is significantly more quiet. A good thing since noise translates to loss of energy, even though I love the choppy sound of the MAS prop.
Content with the prop, I painted the tips by masking them off and applying a white primer and then yellow rattle can paint.
I also touched up the scratches left from the burnishing tool when I corrected some dents. After cleaning, there was one spot around the canopy that needed a bit of paint touch up.
Still need to re-calibrate the throttle range on the ESC and paint the interior of the cowl. The remaining item is the cloth in the tail gear bay.
Let's get the simple things out of the way first. Re-calibrated the ESC. Seems no different. I may do the endpoint method over the standard calibration. Not decided. I tried installing fabric into the tail gear well. The problem was that the clearance is so tight for the wheel to clear in there that any time the fabric would bunch up the gear would bind. I probably COULD get it to work if I spent another 5 hours carefully cutting and sewing things up but it also means more complexity and points of failure. IMO, this has officially become more trouble than it is worth and I'd rather just service or replace the retract should anything happen.
Onto the cowl. Did some extensive research. Found information over at IPMS Stockholm about paint documents on the P-47 series of aircraft. What I found makes a TON of sense. These radials created massive amounts of heat and slung all sorts of oil, fuel, and grease all over the interior of the cowl. Keep in mind that there is not just the engine in there but all the hydraulics for the variable pitch prop as well. All of this hot contaminants would likely immediately strip any sort of paint off an aluminum surface. Therefore, I found that the interior sides of the cowl was anodized. This left a dull and rather dark grey color. Beautiful. This means that I just shoot primer and call it done. Used some masking tape to block off overspray and shot primer easy peasy.
My good friend Carl made a trip over to the Udvar Hazy museum (national air and space museum annex by Dulles airport) and confirmed this by snapping some pictures for me too.
Well, as with all good things, this build has officially come to an end...
A club member was nice enough to donate a couple of hex head screws for the cowl. Every time I went in there to service something the screws would get stripped. A ball-end allen key prevents this. Then after I had re-installed the cowl... problems. Some dirt had gotten into the motor and the cowl flaps were not working properly. Removed cowl AGAIN. Blew out debris from the motor and applied a bit of lube to the bearings and all is well there. One servo mount for the cowl flaps had broken free a little so medium CA to the rescue. Did some re-polish and cleaning in spots and the cowl was back on, prop too, the plane was set for storage/transport. and it was time to clean up.
The final nail in the coffin for a completed build is to recycle the box. It took the better part of 10 minutes to break it all down and stuff it in but it was a labor of love as I cycled through all I had been through on this build. What I learned... like the aluminum covering and polishing, 3D modeling skills, 3D printing, history of the aircraft, and of course remembering my broken ankle. I also recycled the printout of my reference views for panel lines and rivets.
Last was to put tools away and clean the table. While not totally ready for another build it is much better than before. Unlike after the Corsair or Bugatti builds, I'm already getting the itch to do something else. It's funny though, I said after the Bugatti I would not do a crazy detailed build and then I did the Corsair with all of its gimmicks. I did the same after the Corsair and then Horizon suggested this build. How could I say no? The guys at Horizon are really great and I'm not just saying that to blow sunshine. On every interaction they just want to see me fly and have fun. Truly a great experience working with them.
As for what's next? Well, there are events and such in the coming days and months. I believe she will continue to gather compliments and even better discussions around building. As for the workshop? Well, I need to keep it clean for a bit as we want to complete the flooring and baseboards in the basement. I'm not entirely settled on anything yet but I have a list of potential projects to just wrap up.
Top Flite Red Box F8F Bearcat
Top Flite Golden edition P-51 Mustang
Re-build the FFVS J-22 front end and try flying again
Repair and try to fly the HK Nemesis
Or start a completely new project, either on my own, through Horizon, or another sponsor.
Curious about your thoughts on these builds and I would also love to hear what you followers have gained from this build.