Cat blocked from blogging....

Hangar 9 Pulse XT60

One of my absolutley favorite planes was the Mike McConville designed Eflite Pulse XT25e. Apparently, as I review the few blog entries I had on it, I had at least 4. I flew this plane almost every single time I went out, as a 4S. It was fast, maneuverable, stable and predictable. I managed to destroy 3, the last one destroyed itself, and curiously, from a known flaw in the design that I did not manage to provoke before. The wings folded at the bottom of a moderate loop on like the 3rd time I ever flew it. It was a common problem for this plane, likely the small joiner was not enough to adequately distribute the lift forces and the wing commonlty folded in the middle. Eflite would deny this, but why else can an otherwise exquisite design? I miss this one, a lot. Sadly, the main build blog lost its pics in the Great Google Picture Rapture (I deleted a lot of pictures back when Google limited the storage space, not realizing I was also then removing them from the blog posts). What a shame. Simple build, fun to fly.

It was with excitement that I found a flying club aquaintence selling a Hanger 9 XT60, incluing a brand new RCGF-USA 20cc engine, the servos and IBEC (I am hoping its the Tech Aero Ultra IBEC, which knowing Ken, it is).

This is sweet. She is a larger version, is 20cc gasser powered, which if I converted correctly is a big engine for this (I believe that she is designed for a 0.6 glow, which is about 10cc, so 20cc should give great performance). She has a proper aluminum wing spar, so one hopes her classic Hershey Bar wing won't fold. She is pre-hinged, and Ken has done a lot of the build already (pic below), so I hope to be able to plug a receiver in and fly. She would get by with a 6 channel, since she is designed with two aileons (and I would want to program in flaperons, so each their own channel), one elevator, rudder and throttle. I will also need to pick up a wing bag. I think I won't glue the halves together to make her easier to transport. If all goes as planned I will be picking her up tomorrow! More to follow!

Actual Build Photo

The Damnable Cost of LiPos

This is THE reason I don't fly my 600 helis, nor my 30cc sized electric MX-Bach, that need 6S 4500 mAh batteries...

This is an Admiral 6S 4500 mAh LiPO battery from Motion Rc. This is a good company battery, not a PULSE, but very stable witn consistent quality, and a seller that is exceptional. It costs $80. For one. It may last 2-3 years at best. This is a good competetive price. And its way over priced. For twice that I can buy a 10-15cc gas enging and fly it for the rest of my life for pennies of fuel.  Sadly my helis are electric, so I am bound to batteries. My last 6S batteries died out a couple of years ago, so I fly at most 5S, which is fine for my flying style, but I only have 4 of them, and the 600's require two at time in parallel (10S). When those go, I will need to put out about $250 for 4 new ones.  This hobby is too expensive for most two job homes in America... This is likely one reason our hobby is dying out again.

Walbro WA-80 Carb Project: Challenges

The Walbro WA-80 carb arrived yesterday. I am using it instead of a replacement RCGF carb becasue I am curious what effect going from a 1-mm carb to a 7 mm carb might have on letting me lean out the mixture. Performance, efficiency and less oil all over evrything.  It is new and unused, but its box had seen better days: apparently it's one of the last ones out there being Walbro no longer makes them. The WA-80 does fit, but there are a couple of unexpected challenges.

WA-80 on the left, stock RCGF one on the right. It's much smaller, but the faces are the same so it is compatible with the 10cc motor. The venturi is about 7mm but it cones down so on the outside air intake it is about 10mm.

The bottom. Very different here, and the first challenge. The throttle is on the opposite side. I do NOT want to move the throttle servo, so the WA-80 will be going in upside down. The RCGF throttle arm is the longer one. Note that it is desgined to be attached to a servo control arm, and can be removed to be replaced 180 deg. The smaller arm is the choke, which I had a manual control arm on, but never needed.

The top. Challenge number two is the throttle arm is not only on the wrong side, but it is designed for a throttle wire to move laterally across the carb, not fore and aft as on the aircraft servo control rod. How to I tranlate the servo fore-aft movement to lateral movement at the throttle arem? This throttle assembly can come out, but the throttle are is press-fit, not screwed on, so there is NO changing it. This about to beome THE major challenge and it will take a couple of hours to solve.

Removed the idle set screw.

Another view of the throttle arm. That idle screw post is gonna have to go. I Dremeled it off.

Another view of the throttle.

Test fit to see the lay of the land. The wire connector is removed and that large hole is where it was. The hole moves back and forth across the enging, not fore-aft, and the servo control are ain't going to go that way. I thought about how to use the existing linkages to translate the fore-aft to left-right. Nothing worked through the full throttle range. I was going to have to figure out how to attach a control arm on top of the throttle to change the geomety. No way to drill the steel...

I took an epoxy control horn since it is flat and figured out how to best fit it, then trimmed one side, and CA'd it in place. I was able to use two M2 screws and nylock nuts with rubber sided compression washers to futher secure it. It ain't elegant, but it would turn out to work quite well with a little shaping.

One of the screws is through the large hole the other is off one side of the throttle arm.

Another view.

Trimmed down.

Another view.

Engine installed. I would need to trim the servo arm to get full range of motion.

The "underside", installed this is the top. The fuel inlet is now on top, the needles inconveniently on the bottom.

View of the "top" which installed is underneath. Very busy in there.

With the control arm in place. I set it up so that I got range of motion from closed (where the throttle arm would have touched the idle screw arm) to full mechanical open (where the throttle stopped). The throttle in this configuration overshoots full open a few mm, so I need to remove the motor and mark the full open position. I did't think of this until I had installed it, as I had noticed it did this while toying with it while trying to figure out the control arm challenge. I would think it would have hard stops at both ends of the range.

I started working on this after I got home from work at 9pm, and stopped around midnight. This morning, if I get around to it, I plan to remove the engine and mark the real full range of motion, reinstall the engine and see if she will fire up. I will see where the needles are, they are clearly marked  HI aft and LOW foreward, and that about 1.5 rotations would be a nice starting point. It comes with no manual.

If this carb is used on RC engines, the control arm would need to be redesigned and I would prefer it be screwed on rather than press fit allowing 180 degree re-positioning. While it would be more convenient to have the needles on the other side, this would require a major redesign. Most of us install the gas engines with the cylinder down due to the size and trying to maintain the scale appearance of the cowl on those aircraft with one. This makes having the needles on the "bottom" and throttle are on the "top"  of the engine more convenient. When installed the needles are on top and the throttle underneath. This is without a choke, which is good because lordy there is no room for one.

We'll see how this goes! I will update this post, not make a new one.

UPDATE 1:

Air inlet.

Air inlet, throttle leaflet.

Clean look on top.

A close view of the needles. Clearly marked high/low. I put a touch of silver on a corner to mark their location. Each was about 1-1/4 turns out. Nice place to start.

I checked the ROM and the full that I have takes it from the actual full to closed just fine. Lots of distance, should allow for a nice range of speeds with good resolution.

IT WORKS! IT WORKS!

Listen to that. LISTEN TO IT! That is the sound of success! It took about 45 min of tuning about the default setting to find the sweet spot. When they say "screw driver blade width" adjustments, that's what this baby needed. A little too much or not enough changed everything. The high needed very little tweaking. I didn't have the tach set up, but she idled wonderfully without thrust, and ran WOT clean with that sound I know is her max. Transition was sweet with fine resolution, more than this plane and pilot needs. She idled forever, and it was nice to have to use the ignition cut-off to stop her. I ran her over and over again with the same results, so I am pretty sure she is solid. I need to get her in the air to see how she handles altitude and orientation changes, loading and unloading. I am not sophisticated enough to say, but between lowering the servo speed to one second and this smaller carb, she transitions a lot smoother than before. She is back to being a good engine! I am a happy boy!

I knew she would need to be primed from dry, and couldn't fit my finger back behind the engine to cover the air inlet. I made a little thing and it worked first turns.

Going into position.

Obstructing the air inlet.  Only had to do this with the first start, now that the carb is wet shouldn't be a problem, but I will keep this stick in the field box.

Another thing I did notice performance wise, and this was one of the goals. No fuel oil all over the plane. She ran smoother, less four-cycling, and this clean look support that she is running much leaner!

I think this experiment is a success! For production she would need a few design changes, but nothing internally, all easy stuff. This smaller carb may be the way to go!

Why do I blog?

I get asked this a lot because it takes time and effort to keep up at it and I can be prolific. Besides being a narcissist, I do it for the reasons I stated way back when I started it on October 29, 2010. I really enjoy sharing that I am the average pilot. I am a mediocre flier, a mediocre builder, and a mediocre fixer. I know some stuff, and don't know a lot of other stuff. I started with helis, and have been flying one or another on and off for over 9 years, and still can get embarrassingly happy dancey over getting one to go around in a circle and land.

(This is the first pic I ever posted. I have no idea what heli this is... or if its even mine!)

When we go to the clubs, we see all the shiny, all the skills we don't have, we are embarrassed to try new things because we don't understand them, we are embarrassed by the basic things we don't understand, we are embarrassed when we crash or have near misses. Not just because meritocracies make us compare ourselves to others, but also because the others often forgetting their own struggles, can be unknowingly harsh to newbies, house proud. Everyone else seems to know what's going on and got skilz. Most clubs have a Bell Curve of member personalities, but it's not always evident that most love to share and teach. And every club has "that guy" that flies everything 3D, that guy who knowns the tech, that guy who builds marvels. The point is, where do newbies hang out, and who represents them?

Me. I am "Joe Schmuckatelly", the average guy. I am clever, can solve problems, understand how airplanes fly. But I came into this knowing nothing about RC. I had flown three U-Control 0.049 nitro planes as a kid, but I didn't understand them as I had no one to teach me. I started because I like helicopters and bought a Syma 107 (second pic) and loved it. I wanted more. I wasted a lot of money because I had no idea what I was doing and bought the wrong equipment. I quickly realized I probably needed to learn how to fly RC in general, and bought a Spektrum Dx6 and a cheapo foamie Cub from an US Chinese vendor,  immediately putting it in a tree. And I started teaching myself, I started experimenting. I learned that one could join a flying club, and learn how to fly from some really great guys who loved this sport more than their mommies. I had taught myself a lot, and was learning so much in just a few visits at MCRCC, my first club, and I got hooked. These flying monkeys literally got me.

I made a promise to myself that I would blog my successes and my failures, everything. I wanted to share that everyone first learns to move the pawn, and that most of us are mediocre and that is just fine. I wanted every persons to know that we are all making this up as we go along, that even pros shank one into the ground on a regular basis, that the hobby is "more fixing than flying", and that they were right on track with everyone else. I wanted to share that the hobby is for everyone, not just the 3D stars. That "276 days since my last crash" counter is so high because I didn't fly much last year, and winter came. Usually it's about a week. Don't be impressed. If you aren't crashing you are trying hard enough.

So read. Enjoy, and realize we are all doing just fine.

All I need is the new Walbro

I took the Stik out to the garage today to see what would happen. In my last post I noted that I had thought I found the sweet spot for the idle, albeit high.

Recall that the carb kept needing tuning every time I took it out. Recall further, I screwed this engine up when I rebuilt it trying to get better performance, when it already was fine. It was my first RCGF, a few years old, and needed a cleaning anyway., so I rebuilt it and the carb, and it's never been right since.  Joe Nelson of RCGF, and I are sure it's the carb.

Well, the carb went back to its antics and ran great WOT and most of the time at half, but idle dropped to a high idle probably around 3500, then would slowly step down and then stop over  aminute. Am I crazy thinking an engine should be able to sit at idle indefinitely?  In my last post I noted I purchased a Walbro WA-80 carb, which is no longer in production. I found two new ones at about the same price on eBay. On Flying Giants a poster noted that a smaller carb works better for these small engines, so instead of the stock 10mm, the WA-80 is about 7.1 mm. They note far better performance. So I took the engine off the airplane, and removed the carb. As soon as the new one gets here I will install and put this thing back together. I can't wait to get this engine back to it's flying performance!

I also slowed the servo to about 0.7s, and honestly, it provided a nice smooth progression from idle to WOT. I may do this on all my gassers. It lows the transition in the carb preserving the vacuum, as opposed to jamming it forward and losing vacuum causing the engine to lean as you need more fuel.

RCGF Updates

RCGF updated their website! Sweet look. By the way, saw they are selling the 15cc Beam Mount side muffler engine for $209, the rear muffler for $199. That's the same price as the 10cc. And a 30cc TWIN is coming. Check it out!

I have had great luck with these engines, except for the 10cc on the Stik. I think it's a bad carb... The need to re-tune it every time I start it suggests this, and the curious way it runs at times, like there is a fuel flow issue. Joe Nelson thinks its the carb too. I finally decided to change it. I went to the RCGF website yesterday and it must have been while they were updating it as the website URL could not be found. Gave me a fright that it folded! Nope, as noted, new site. But since they were closed at the time, I went looking for what to buy. As I looked at Google pickings there was a discussion on RC Universe about carbs on these RCGF and similar engines being too big, like 2-4 times too big, and that this made them run  inefficiently, rich.

** RCGF-USA uses only Walbro carbs now.**

"I would offer that the carb that comes on the 10cc rear exhaust engine is a Walbro clone with a 10mm or so venturi, that is 3-4 times the size it needs to be. To get good throttle response requires a super rich low speed mixture. After many hours messing around trying to civilize this engine, it was discovered that if you slowed the throttle opening using the same process you would on wing flaps or gear doors, allowed for a dramatically leaner low speed mixture.

Those with automotive hot rod experience might relate to a comparison of having a 1050 Holley carb on a 302 small block, using mechanical secondaries. When the carb is opened quickly there is a complete loss of vacuum causing the engine to fall flat on it's face. In the caes of the 10cc RCGF, slowing the carb opening allows the engine to maintain vacuum, resulting in a much more desirable acceleration.

Worth noting is the slow carb opening is not noticeable in use, and the engine handles nicely, much like bigger rear carb engines, and flip starts easily."  ~ AHICKS

Going smaller might lead to loss of WOT RPM, but better and more linear power. The stock carb is 10mm, and the discussion was bringing that down to 7.1mm using a Walbro WA-80 carb. Well, I could not find one... I even wrote Walbro (they are not making them anymore but are thinking about it... and would need a run of 40 before they reopened the line; email with Walbro). The WA-80 supposedly is a perfect retrofit for the stock Chinese one (which, by the way works just fine on the Sukhoi RCGF 10cc). So I bought one of the only two available new, on eBay for $35.

While I do like the Evolution 10cc, I still have lost my heart to these RCGF engines. Hopefully this solves this problem with the Stik's RCGF 10cc. I haven't tried running it since the other day when I finally got her re-tuned again. Her high idle shouldn't still be an issue... We'll see.

The other suggestion I have seen for these really small engines is brought up again by AHICKS:

"Worthy of note, when installing the Walbro carb, many advise the use of some sort of thermal break between the engine and carb. I laminated about 1/4" if fiberglass scraps together with some CA and carved one out from that. A stack of gaskets may work as well, or, see what happens without!"  ~AHICKS

I don't have any materials that I know of to make this thermal break, so will try it without it... Not sure this is a thing?

SCUTTLEBUTT:  Well this is interesting...  VVRC used to be a drop shipper for RCGF-USA (You order from VVRC, but the product is sent from RCGF-USA). RCGF-USA makes these engines in China, but the company is US owned. There were issues with the molds they used in the early years. RCGF-USA developed their own molds for these engines and have solved the QA issues, and now produce great engines at great prices. More importantly, they have always offered personal, outstanding customer service. You talk to the owner, not an employee. I have used VVRC in the past and am disappointed in their aggressive and inflammatory posting. I don't know where Tom is getting his RCGF engines, but if they are from those old molds, buyer beware... I would not buy any RCGF product from anyone but RCGF-USA.