Need 46 size engine help

OS claims to have solved their problems with peeling cylinder linings. Just make sure that you don't buy old stock. The Thunder Tiger 46 Pro is a very fine engine. I suspect that those complaining about them didn't take the trouble to break them in properly. They do take about half a dozen runs before they settle down to excellent engines.

Jim - AMA 501383

Dean wrote:

No amount of money is going to save you from having to tune whatever engine you choose. No amount of money is going to eliminate deadsticks. Both are the reality of the hobby.

IMHO, the Thunder Tiger's perceived "problem" is simply a tuning issue. It's been my experience that most people tweek the main needle until the plane is screaming at maximum RPM, point the nose of the plane in the air without knowing what it means, then go fly. In other words, they don't know how to tune their engine at all. This leads to problems, deadsticks, and undeserved bad reputations for many engines. All the Thunder Tigers I've flown or seen fly have been as reliable as a glow engine can be.

OS revised the plating process on their cylinder liners about two years ago amid much fanfare about how this new plating process was an improvement to an already-perfect process.

The OS lining problem was solved some time ago. Great engine. I dont own one as yet but every owner of one that I know loves it.

I have 2 OS .46fx engines. One older and one new. Both run great, and the new one, AFTER adjusting the idle speed after a couple of tanks, has a super reliable very slow idle. Haven't had a dead stick. I run 15% nitro fuel.

Bob

Doug, This is not anything other than a simple observation. I have noticed that some of the guys I know who fly both spend an inordinate amount of time fiddling with the glow engines trying to get the last RPM out of them. I have begun to think that our AR portion drives us to things that do allow for fiddling. On the other side, I just dial the glow in and go fly and view playing with prop/gear combinations not to my taste or pocketbook.

Jim Branaum AMA 1428

Six_O'clock_High Target snipped-for-privacy@Guns.com

I quit flying electrics because I like different planes and each plane needed a different battery size, type, what have you. I would spend most of the previous afternoon, and all evening charging everything up then be out of juice and sitting on my hands in the space of 20 minutes or so at the field. Phooey! Slope or glow for me.

Thanks for the input, but I didn't ask about electric power, and neither did the original poster.

Happens more often than you think...

I fly electric too. When my batteries dump, there's little usable power left. In fact it actually hinders the plane more often than it helps. IMHO, if you run the plane to the BEC cutoff, you're essentially deadstick. There's no going around for a second try at landing.

All that stuff costs a lot more money than a little needle tweaking, though. You can't just add a cell to a pack; the pack must be discharged, then partially disassembled so you can add the cell, then slow charged to bring the cells back into balance. It's a 2-day project.

Maybe I'm just impatient, but I never spend a whole lot of time tweaking an engine on a plane, and the few deadsticks I do have are always my fault (i.e. throttle too low). If an engine won't tune, I know something else is wrong. This year, it seems to be holes in the fuel tubing. You can't blame that on the engine, or glow power in general. It's my fault for flaring the ends of the brass tubing on the fuel tanks.

I think I'm going somewhere with this, but I'm not sure where... Ah yes, most of the problems people have with glow power are self-inflicted.

Yes, but you did make a sweeping generalization. | > With an electric, the only way you get | > an dead stick is if your prop flies off or breaks, your engine burns | > out or something else fails. | | Happens more often than you think...

I've had one prop fly off and one (cheap-ass 180 GWS) motor burn up in flight in the last two years. In the same time, I've probably had 100 IC engines die in flight.

| > Instead, you find yourself with less and | > less power. Your BEC may turn off your motor, but throttling back and | > then forward again will usually give you a few more seconds of thrust. | | I fly electric too. When my batteries dump, there's little usable | power left. In fact it actually hinders the plane more often than it | helps. IMHO, if you run the plane to the BEC cutoff, you're | essentially deadstick. There's no going around for a second try at | landing.

In my experience, it usually cuts out the first time if I go to full throttle for a bit, so then I go to half throttle and have another minute or two of very gentle flight. Of course, the plane that I fly the most has a brushless motor that sucks a lot of current, so that's why the BEC engages so early. But even my slow park flier (a Tubby Cubby, all stock except for a beefed up wing) give me plenty of warning before not being able to maintain altitude.

| > As for tuning, you'll try different battery packs, different props and | > maybe different gear ratios, but there's not fidding with things at | > the field trying to get the $^#$& thing to run. | | All that stuff costs a lot more money than a little needle tweaking, | though. You can't just add a cell to a pack; the pack must be | discharged, then partially disassembled so you can add the cell, then | slow charged to bring the cells back into balance. It's a 2-day | project.

I should have also mentioned that all that stuff is optional. If you buy a plane with a suggested motor, battery and prop you can just use that and be fine.

| > | Both are the reality of the hobby. | > | > I find I've spend more time fiddling with my engines on my glow planes | > than I've spend flying them lately. Perhaps that's why I fly the | > electrics (and gliders) so much lately ... | | Maybe I'm just impatient, but I never spend a whole lot of time | tweaking an engine on a plane, and the few deadsticks I do have are | always my fault (i.e. throttle too low). If an engine won't tune, I | know something else is wrong. This year, it seems to be holes in the | fuel tubing. You can't blame that on the engine, or glow power in | general. It's my fault for flaring the ends of the brass tubing on the | fuel tanks. | | I think I'm going somewhere with this, but I'm not sure where... Ah | yes, most of the problems people have with glow power are | self-inflicted.

Absolutely. I don't tune my engines for top performance -- I just find the peak, then back off a little and leave it at that. I still haven't gotten down adjusting the low end quite right, and I think that's a lot of my problem. But even so, I'm always running into and fixing problems with fuel line pin holes, leaking fuel tanks, crud getting into the engine (even when I use filters), bad glow plugs, etc. And then there's the problems I never find out what they were, but they sometimes go away after replacing the entire fuel system or taking the engine apart and cleaning it. Sometimes.

Self inflicted? I can't argue with that. Unfortunately, I can't take myself out of the equation. :)

Doug, I learned the 'correct' way to tune the low end from George Aldrich. He gave me instructions at the LHS one afternoon when I was complaining about loosing the engine at idle on a regular basis. I tried it and have rarely lost an engine due to flooding or too lean on the low end.

This is for 2 strokes with two needles (low and high speed) only. First get the top end near right with the tank 1/2 full. Then bring it back to a fast idle. Slowly bring the idle down to where you want it. Then you get your glow driver out and put it on the plug. If it speeds up significantly, your low end is too rich. Most of the time you have to kill the engine to turn the low end needle unless you are extremely careful and have the right tools which vary with carb type. Now if it did not change RPM when you put the glow driver on it, you are either right on or too lean. To check for too lean I use the 'pinch' test. Pinch the fuel line briefly just before the fuel enters the carb. If the engine speeds up, you are fine. If it quits, you are too lean.

Two words of warning here. First is that after the engine is broken in you will need to re tune it. The second is a bit more important. Whenever you change brands or mixes of fuel, recheck your low end setting after about 5 tanks full of the new fuel. There ARE fuels out there that have extra stuff in the oil that burns with the fuel so you may become too lean or too rich when you change the fuel. In one particular case I know of the newer fuel made me lean out the low end almost 1/2 needle turn.

Hope this helps you a bit

Jim Branaum AMA 1428

Six_O'clock_High Target snipped-for-privacy@Guns.com.

Excellent technique suggestions, Jim --

May I also suggest that for final high end adjustments, use a tachometer and lean the needle for peak RPM, making a note of the peak. Then ever so slightly richen up the needle so that the RPM is somewhere between 300~500 RPM less than peak. This allows for prop unloading in flight.

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