Finally, a flying day!

Dark, heavy, but high clouds threatened rain, but the drought made this unlikely, a coy deception. Pretty much windless, and a comfortable mid 60s temps, I had been itching, and Saturday afternoon was time to scratch!

Bill Renault brought out a couple of fun old school classics. This nitro 2-stroke of course flew marvelously, that sweet nitro smell and soft purr powered her through the skies effortlessly!

He also had the Sig 4 Star 120 with its awe worthy 4-stroke. 

Bill flies 72 mHz. He clearly enjoys flying and talking about flying! He was wonderful company at Wagner. Clarence, who I swear lives in the filed shed, was there since morning, and hung around to chat. Always nice to see him. 

Anthony was there too, flying the little mosquito of a 370. This is an old pic as I don't think he stopped flying the whole time he was there. I suspect he flew the bigger one too, getting in 14 flights! Perfect temps and winds for these guys! He reminded me I need to be bringing my helis out!

I got in about 5 flights, most about 10 min as the engine is still running rich in flight, or theirs an airleak in the carb path. Starts fine, runs with power but in the air she starts popping and running "wet".  She is always an amazing flier! I plan tomrebuild the carb, not sure if I have done that before. She used to be an amazing engine, an RCGF 26cc. At some point this year this rich running airborne became a problem.

Brought the Hangar 9 Ultra Stick out to maiden. Engine ran just fine, but the Twitch Curse showed up, so I grounded her on the runway. Just drove her around a bit. Man, I really wanted to fly her...

Its Baaack... The servo twitch curse.

The Ugly Stik had this aileron twitch I could not get rid of... it eventually lead to the loss of the Stik. I guess I haven't fired up the Ultra Stik with the wing on, because I would have noticed this twitch curse has come to the new plane. I had her out at the field and set her up, excited to maiden her, even drove her around to range test her, but I noticed that at idle and WOT the twitch showed up, curiously not in midrange. The video doesn't capture the worst of it, it would occasionally go full deflection. The only parts that are the same are the Hitec HS-485HB servos, except for the elevator which is new. Odd, the left aileron is again affected, and the elevator! The connections are all solid but will get a second look. These are usually voltage issues.

Needless to say, I grounded her, "fool me once" sorta thing. I am thinking about the facts: only the servos are the same. I ave no idea why its the left aileron again... The elevator is a brand new servo; the old one locked up and failed without the engine on. I am thinking these discontinued Hitec HS-485HB are the problem, but possibly fixable. The other clue is that with the engine off they are perfect, no twitch, rock solid, function perfectly. This suggests the ignition is somehow involved. Now the ignition is in perfect condition, and this is a different engine, the EVO 10cc and its CDI. Its a different battery from the old Stik. This aircraft has a simple RCexl opto remote kill switch, not sure if it was on the Sbach or the Stik... 

So here's my plan. I can't afford to change out the aileron and elevator servos to higher end digital metal gear servos at about $35+ a pop (I would need 4), so I am working up the food chain.

1. A capacitor.  The theory here is that the twitch is from voltage spikes and drops, and the milliamps stored in the capacitor acts to buffer this letting those variations come from the capacitor per se, and not the reciever. This plugs into a spare port on the reciever. I am not sure they work, and people seem to find them controversial as to their effectiveness or need for that matter. This one from Amazon for $8 delivered (had a coupon, cost me $3).

2. Tech-Aero Ultra IBEC. This is what I prefer to the simple RCexl remote opto switch. The optical switch is supposed to isolate the electrical noise from the ignition and keep it out of the reciever by using a optical interrupt (the electrical signal gets turned into an optical (photon) signal, back to electrical, with that light isolating the two sides from on another, or something like that). It runs about $17. The Ultra IBEC instead filters the signal 4 times through various capacitors and then stabilizes the power to remove any noise. I honestly don't know if these have any functional differences otherwise. They both could be replaced from a noise cleanup standpoint, by using a ignition only battery. Clearly if this is an ignition noise issue the RCexel switch is not stopping it. Since I think it would, if the IBEC instead works, then its a voltage stabilizing issue that the capacitor could not solve.

3. Change the servos.  People knock "budget" servos, but honestly the only difference I have seen is initial quality. If they work out of the bag/box, they work fine, but yeah there are some junk brands out there so you have to know what you are buying. Reviews show these to be very reliable and I get 4 metal gear digital servos for a great price, $18 for 4. I have never had one that failed, even out of the bag. Someday when I can drop $150 on 4 name brand servos I may change them, but right now, this is the way to go.

I will probably end up doing all these things, leaving the Hitecs on the flaps, but one at a time to see what fixes the twitch. Something has to work...

New Aircraft are ready to Maiden!

 

The Hangar 9 10cc Ultra Stick has her balanced prop on and is ready to go!

Got the cowl on the Phoenix Spitfire, and checked her CG: SPOT ON no changes necessary!

Looking good. I am ready to give this, my third Phoenix Spitfire a run for my money. I have had two previous ones perish on maidens. The first when I clipped a tree coming out of an intended stall, the second when she stalled on takeoff and torqued into the firmament. I have no doubt this one is the one.

Lit the fires on the Ultra Stick

No pics today, but I got the Ultra Stick out to the back on the test table and ran her up. Started right away, needed a little tuning. Produce 5.2 lbs of thrust with the 13x8x3. Then the uncollapsable table leg collapsed in front and she dropped on the prop still attached to the fallen front of the table. I was a bit pissed so didn't take any pics. 

The engine ran ok, but was really slow to run up, and thenreally slow to come back down. I leaned it out I  the low end and she is running pretty well. I was pretty much finished when the end of the table collapsed,.

The elevator servo went rogue. I suspect this is the bad one that killed the Ugly Stick? The tests could not find it, but it went really jittery and then locked up, already ordered a replacement.

I think once ai replace the servo she is ready to maiden!

Yikes, a 9-1/2 lb baby...

I mentioned previously that the Hangar 9 Ultra Stick 10cc was quite tail heavy, and that test fitting the  455g (1 lb) lead block I happen to have from a dead Eflite Stearman of long ago balanced it out perfectly just forward of the CG, and I mean just forward. This is no child... its a manly block of lead. There isn't any room to put any lesser weight in the tank area.

I created a partial wall forward of the lead block to support it, with some lightweight plywood (thought I had a pic, but alas...). This is the block in place, the Dual-Lock Velcro is CAd in place on the base and the "back" against that wall. The foam is to add some compression when the wing is in place to dispel any notions it has about wandering about the cabin in flight.

The CG machine verifies my finger-tip test.

The CG is now spot on.

Concern is that her spec weight is 7 lbs, and she comes in at 9.5 lbs dry. I didn't see a different spec weight for electric vs gasser, and I have no doubt my Ugly Stick was heavier than spec too. This heavy-lift wing will undoubtedly be up to the job, but...  One thing of note, seen in this last pic, is the long length of those landing gear. Hope I don't see too much flex from the extra weight.

Planned to light the fires today, but its fixin' to storm.

The Bad Cylinder Revisited

Joe Nelson of RCGF-USA had asked me to check the top of the piston on the RCGF 10cc engine I had reworked to fix a stripped spark plug hole, after it blew out. Was it soft metal, as we expected, or had the piston pounded it out? I was between bench jobs so I took the cylinder off.

Conveniently three of the hex top bolts holding the head in place stripped... so I had to grind them off then bang the head off (easy, killer...). 

The piston top is smooth, no evidence of it striking the adapter. There is some damage along the rim of the spark hole seen at about 12:30 on the right in the cylinder head that wasn't there when the adapter was installed.

I wanted to use a Walbro carb, the the reed plate bolt holes that secure the carb to the crankcase had stripped on one side. I figured why not retap it, and that worked. Snug, tight, not gorilla tight. This was a cantankerous carb. I oiled up the cylinder and put it in a plastic bag. When I can afford a new cylinder I will get one from Joe. I don't have a plane for her right now, though, but that, as we know, is never an obstacle. (I can't find a round cowl WWI plane, like a Sopwith Pup or Nieuport to put her in, my first choice. Second is the Phoenix Zero. My heart is on a WWI biplane...).

Hangar 9 10CC Ultra Stick Completed!

 The Hangar 9 Ultra Stick 10 cc project is done, and it was some kind of journey. I've not had a build shift course so many times. Its not where I was going, but its where I intended it to be.

It started out straight forward enough. This was the original design of the equipment bay. This was based mostly on the ginormous reciever/ignition battery, a 2S 5200 mAh LiPO I had bought for the test bed, but instead decided to use it on the Stick. Its weight is about the same as two 2500 mAh NiMH batteries. Its a hard case battery, and its size limited options for the other equipment. I couldn't use the standard size cut out that runs across the fuse at the front of that tray because the battery covers it. I was planning to use a mini servo for the throttle, and had to chisle out a mm here and there to get that to fit. You will notice there is no throttle control rod. At this point I wasn't sure how this was going to work. This plane was designed around the now discontinued Evolution 10 cc engine that I am using, but I am not sure where they thought the control rod was going to go through the firewall straight to the throttle. Was planning to solve that problem later. Even then it wasn't going to be straight, as you will see below. The satellite is forward on the starboard side. None of this plan would survive first contact with the enemy, except the reciever.

This original design survived. I made this connector to allow a single output from the battery to split to the ignition and receiver electric switches. I had soldered a single Futaba connector to the main leads of the battery. This resulted from my having to cancel the order of the Hobby King Turnigy Battery Switch as by day 8 it still hadn't shipped, instead I went with the dual Miracle switch I had on hand. 

This is the battery harness in place on the switch.

I was now going to have trouble placing the switch. It was going to need me to move the battery out of the way, but there is no room for that, unless I cut the deck and allow it to rest on the bottom. Remember that everything forward of the servo on the port side is reserved for the control rod. Initially I planned to lay it flat under the deck, but there was no way to get it in there. I changed the idea again and decided to make it lay vertically. The landing gear hard point would be under the front, so it will be angled, but the highest part, forward, would still be under the wing that forms the top of the compartment.

So, I made a vertical tray. Since the battery is a hard case, and its a 80C only running a receiver and ignition it will never puff, so close quarters are fine. Not really sure what happens when hard xase batteries puff...

 

To give it a clean look I painted it black.

Looking good.  I still wasn't quite sure how the switch was going to fit, or where.

While that was drying, I moved to the landing gear. This is a sturdy metal tail gear assmebly I used for two reasons. I had gone back and forth between using the stock straight plate with it's connection to the rudder, a design that can put a lot of  stress on the rudder hinges as the plate doesn't completley protect them from jostling forces on the gear shaft, transmitting them to the rudder and therefore the hinges. Also, I am using the big wheels from the Ugly Stick, so the low set stock tail assembly would lead to a bit more angulation of the fuse and endanger a rudder strike. Lastly, I wanted something sturdy. The reason I like the larger wheels on both Sticks was to allow it to fly off rough surfaces, as when I first flew the Ugly Stick it was off the clumpy grass at the Bedford field that claimed so many landing gear. Flying off that rough a surface won't be much of an issue now, but I do like the look.

Here she is, on her wheels for the first time.

The engine installed. I removed the two muffler extension pieces that were needed to get the muffler out of the wide Sbach cowl, and she is back to stock configuration.

I made a fuel vent. I don't know why these are so hard to find. I don't like a simple tube running down. Here I used a fuel dot rim, and a clunk with a flat bottom that I JB Welded to one another. The clunk just happened to fit in the rim! Came out swell!

I want the satellite to be aligned vertically. In the equipment bay it was going to be severely blocked by the battery. I decided to move it aft as far as I could. I can't get back there easily so I came up with the idea of putting it on a boom and getting it back there.

You can see the satellite block aft of the reciever here. Its set on a platform I made using Dual-Lock velcro. Here you can see the switch in place. I used the stock switch cut out on the port side, enlarged it a bit. You can see how the switch is kinda deep and would not fit on  the starboard side. You still see the mini servo...

So this is where the bay layout stood for a few minutes.  It is packed. Still working on ideas for the control rod at this point.

With all the angulation back and forth in the control rod path, I figured the only way I would get something to work was to use braided wire, its flexibility making it a working solution. After several tries I managed to solder the Du-Bro linkage to the wire. In practice however, the final path took a sharper angle at the end near the throttle than the wire would allow making it too flexible at a point that elbowed, transferring the movment to flexing insetad of to the throttle linkage. I tried hardening it with solder, but that only partially solved the problem. I decided to try a softer, smaller diameter flexible solid control rod. That worked better than I had tought. I changed the throttle control rod connection as well as I couldn't get the Du-bro connector to solder to the rod.  I did have to drill a new passage throught the firewall taking the engine mounts into account, making for a straighter path. New problem: the micro servo was working with both designs, but taking a lot of strain to do so due to friction in the path. It was going to need a standard servo.

Here the standard servo is in place. Once again had to do more cutout in the already trimmed out servo tray. and build up the servo hardpoints. Here you can see the control rod in place. I used two pieces of thin plywood to create a hardpoint as the rod passes into the guide tube. This stiffened the path so the softer control rod could would be more efficient in transfering the movement to the throttle.

Here I had to remove the engine and mounts to drill a new pass through hole through the firewall to creat a straighter path. The engine still blocks the path, which as you can see below, required a cut out of the mount strut itself to keep a sharper S curve out. Epoxied this in place,, but the firewall is almost a cm thick. I could have drilled a hole into the mount from behind, but I didn't think of that until now... I will go back and do that, I think.

Here is where it passes throught the firewall on the engine side. I had to grind a big dent in the engine mount strut to allow it to weave pass the base of the engine. It remains hard against both but more or less straight. The stock design has the engine upside down as I do it, so I have no idea how they connected this.

You can see the tank is as far to starboard as I could make it. The path is pretty much straight now, except after it passes the firewall and runs into the engine. The ignition is in a small bay directly underneath.

All up! Did the programming last night into the iX12. Need to set the CG and weigh her. All in all I am quite pleased and hope she flies well! 

Hangar 9 10cc Ultra Stick ARF. Evolution 10cc gasser, Evolution CDI Ignition, with a 13x8x3 Master Airscrew prop under an aluminum spinner. RCExcel optical ignition remote cut out. Zeee 7.4V(2S) 5400 mAh LiPO receiver/ignition pack in a hard case, from Amazon ($17 shipped!). Miracle power switch. Spektrum AR7010 receiver with one satellite. Sullivan 4" tires. Don't know the make or source of the tail assmebly, but its for a 50cc aircraft and easy to find as there are so few options out there. Could find a decent one for 10cc 0r 60 sized airplane.