Spitfire Engine Blown Sparky, Kaput

I thought that I was nearing the end of the Spitfire #3 build, but during the engine run-ups the post-crash RCGF-USA 10cc I just didn't like the sound of the engine, and she didn't seem to get up to full RPM/power. I found the following thrust results, average of 3 measures of static thrust, the aircraft weighs 8 lbs dry. Using a Thrust to Weight ration of 0.7, the plane would fly fine with 5.6 lbs of thrust (I couldn't find any other estimate of Thrust to Weight for gas):

14x6x2: 5.4 lbs

13x6x2: 4.2 lbs

13x8x3: 4.4 lbs

She just doesn't sound right. I am not confident the bearings, especially the front one, are okay, and I think she should produce more RPM.

The spark plug stripped, I think it was coming free during these run ups, and afterwards it just came loose, and it wouldn't tighten. I will be sending this engine to Joe Nelson at RCGF-USA to take a look at and see if he can solve the problems he finds. I suspect she will need a new cylinder head and bearing(s), possibly a new spark plug. 

In the meantime I am considering taking the RCGF-USA 10cc from the Sukhoi and moving it to the Spitfire. That engine runs perfectly, is the same exact engine, and would be a simple exchange. When the repaired engine comes back I can put it in the Sukhoi. I am stalling on that because it runs and works perfect in the Sukhoi and I don't want yo screw around with that. Patience...

Spitfire #3 Essentially done!

Last night I essentially finished the third Spitfire. I installed the fuel system, engine, and the electronics, the wing is joined to the fuse and everything works!

Rather full upper equipment bay. Fuel tank forward, reciever on the starboard side, 2S 2300 mAh LiPO on the port with the mai  power switch on underside of  th throttle switch. Snug and cozy.

I really like the simple switch from Hobby King. Its electronic so will fail "on", and has a nifty multicolored battery charge detector. On line in, one out. I hadvto trim of the handy flanges. Great price even if shipping was steep, almost the same price as the part for the guy on the bicycle speed delivery.

Another view of the equipment bay, looking aft.

The cowl is done, the engine and muffler holes cut out and it has been fitted. Needs to have needle access drilled out still, but its done. Leaving it off for the first engine start to make sure there are no issues. That's really all that is left, first fuel, first start and run up!I do need to find some letters for the side, didn't like the ones ai got for being too narrow (ordered them online, didn't get a good look). I'll put my initials on either side of the fuselage rondels.

Dry weight is just shy of 8 lbs (~ 3.6 kg).

Spitty Update: Wing joined, Tail feathers done

Tail feathers done. Completed the horizontal stabilizer and the rudder, connected their control assemblies.

I completed the wing Y harnesses and joined the wings. I decided as before that its just easier with all the wiring.

Tail feathers and wing joinery setting and drying.

Elevator and rudder servos and their connecting rods.

Red fuel vent. I decided this time to put it aft of the wing. There isn't really a good place anywhere forward.

I also plumbed the fuel tank, clunk and vent. I am thinking about how to get the 3-way in place without crimping it with a tight turn while keeping the line to the carb short. 

Next I will set up the engine, then the electronics.

Spitfire #3 Underway

Tempting fate, trying a third Phoenix Models 10cc Spitfire. The first two were both lost on their maiden flights. I am resolved to greak the curse.

And AWAAAAAY we go!

Thought these servoless retracts were $17 a piece from Hobby King. Nope, a pair, says so right there on the listing, so I have an extra set of retracts.

The box, she be opened. No ghosts or wights came out, whew....

Fuel proofing on the front inside of the fuse drying. I kinda sm stalling...

Wing one. Let the games begin.

Painting the wheel hubs white, the flap well is primed, will be painting it red.

Tip: I learned before to put the flap control horns on first, then install the flaps. To do this the servos had to go in first so I could know where the horns would go. I amusing Tactic 47s from previous models.

Wings are done! Took about 3 days, mostly due to issues getting the landing gear to work right (see below).

Red came out great! Not sure how I am going to set up the flaps...  They are on a Y, so I am not sure how I will get the end points to match. I don't remember how I did them before. I am using an 8 channel receiver.

I wonder if I should leave the landing gear cover off to keep the underside of the wing flat and unobstructed? The gear is well into the wing with the changes. 

Once again putting the non-stock servoless retracts on took a lot af work, trial and improvements on first takes. I haven't done them quite the same on any of the three models  but this approach worked the best.  The issue is they are full 90 degree retracts, and if it binds at less than 90 retracting up, it gets stuck, won't budge, and is locked.had to remove them to let them unbind. That's how I figured out what the problem was. I had to raise the hardpoint the thickness of a popsicle stick, which I tailored two for each gear. Further I had to make a round hole in the center of the wheel well creating another 1 cm of space by allowing the head of the bolt holding the tire on to pass through and a bit under the well. Lastly I had to trim one of the gear cover support brackets so it wouldn't bind on the gear retract body. Now they work perfectly! Took some tiresome trouble shooting to figure this out, and the differnt sites causing binding.

As with the last two Spittys I had to cut the back off one of the gear cover supports so the gear could retract completely, not blocking full retract by running into the body of the retract.

My, that is a big bolt head right there... It ran into the wheel well cover before it fully retracted, causing binding. Partly relieved by raising the hardpoint, and by making a space for the bolt head in the bottom of the well,

Melted with soldering iron then Dremel sanded a hole in the center of the wheel well for the gear bolt. The underside of the wing is several mm deeper, more than enough room for the bolt. I located the spot by removing the wheel and reinstalling the volt by itself and seeing what it ran into. Made the hole there.

Taking a break. Next how to fit everything in. Using a single LiPO with a Tech-Aero UltraBEC, saving space and weight. I am going to use a Hobby Eagle 3-Axis stabilization system on it*. Not sure where that's going. The receiver is a big Spektrum AR8010T with a sat. Not sure where that's going either. 

More adventure to come!

* Um, nope. Says specifically not for glow/gas aircraft. This solves another problem, lets me assign separate flap channels if I need them.

Test Stand and RCGF-USA 10cc Survived

I had removed the RCGF-USA 10cc from the Stik that took a massively destructive header right on to the engine. Before I committed it to the new Spitfire, I wanted to make sure that it survived intact. All tree blades were snapped at the hub and she came down right on the hub, which is ground up quite a bit.

The RCGF-USA 10cc on the newly built test stand.

Runs perfect!

A simple rig. Manual throttle, the ignition  is fro  the engine and will be installed on the Spitfire. On old NiMH battery pack and the tachometer are also fixed to the rig. I put the 10 cc mount on one side so I can put a larger engine ,out on the other side if ever needed. 

The RCGF-USA 10cc on the test stand. Brief cut.

HK 500e FBL Main Bearing Plates and a Bad One-Way Bearing

The new bering plates came in and I went to install them today. I found the plate to be 5mm too narrow! It's always something...

I had some 3 mm plates of very dense wood and use them to make the gap. 

Worked fine, very solid as the wood is so dense.

Tuned up the 4 blade head.

Now this was curious. The lightest blade was the "heaviest" on the balancer. It weighed in at 56.7, and on the right that's the heavier one at 58.2! I rechecked all the weights and they are real. The blades CG are all about the same. I have no idea why this is. So I balanced them all to the "heavy" blade.

I had planned to use 450 size blades before I realized that the grips only fit the 500 size. 

I may have to fly her 6S, fortunately have plenty of them.

She is all set! But, wait! There's more! I took her out to check her tracking and she swings the big blades fine, the tracking was perfect, and she was acting balanced. But, the one-way bearing is shot and slipped with the extra weight. It's the original so I am not surprised.

I ordered a whole new main gear one-way bearing set so its all fresh, from Amainhobbies. good price, great shipping option.

Blown bearing!

I've never blown a bearing before, but I shredded the lower motor bearing today on the Trex 600e FBL. It's been making noise since the hard landing, and it was bad today when I spun it up to test the new tail blades, so I checked it out. I suspect it's because one of the two motor plate screws came off the right side at some point and were lost, so the motor was not secure.  I didn't notice this until I was removing the bearing plate. I had to chisel the outer frame of the bearing from the plate and it took some work to get the inner run off the the motor shaft; had to pop the pinion off to get the remnant off. Ordered some 6x12x4 metal shielded bearings to replace it, didn't have one in stock. Took the opportunity to oil up the Scorpion motor bearing. Replaced and re-Locktited the motor based screws. A few screws were missing on the right side of the frame... checked all of them. I ordered the new bearings from Amazon, will be here in two days.

The bottom of the main gear should not have been rubbing on the torque tube power takeoff gear, so I rechecked the location of the washers on the manual. I was surprised to learn that the 0.3mm and 0.5mm washers are put together, and that they go  under the main shaft stop over the top main shaft bearing. This lifts the entire mechanism and will make the main gear and the power takeoff gear clear. I had them together but on the top of the main gear hub, immediately under the lower main shaft bearing plate. To remind me I put them on the shaft over the clothespin.

I found that the top of the main gear metal hub was rubbing the underside of the lower main shaft bearing plate. There was some metal stripping off the top of the main gear hub. Not sure what's up with that. Was it not seated properly because the washers were in the wrong place? I hope so.

 

UPDATE: Replaced the bearing, hover tested, perfect. Quiet, smooth, balanced, ready to fly again!