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Post by Garf on Feb 8, 2008 21:33:27 GMT -7
Engine has been recieved from Tom Hampshire. Looks and feels good. I'll probably bench run it once to see what it sounds like before flying it.
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Post by Garf on Feb 9, 2008 19:52:01 GMT -7
Bench ran the Brodak 40 today. I decided to try it on 0/12.5/12.5 (no nitro) fuel mix. It started easily and 4 cycled well. It seemed to lose power when leaned out. On 10/10/10 mix, it sounded similar, but more power. Time to test fly it.
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Post by lfinney on Feb 13, 2008 13:55:37 GMT -7
one run or two under a good load in a high humidity setting is all it takes, 4-0 steel wool or brass wool with mek or acetone to scrub off varnish will do the trick..
i had this problem when i resided in michigan, but seldom in southern cal free flighters who used cox products and iron piston engines added some #9 hoppes gun solvent to fuel.... this boosts perf and cuts down on varnish
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Post by Garf on Feb 13, 2008 21:53:28 GMT -7
Welcome to the forum. Tom Hampshire claims that 12.5% castor and 12.5% Klotz mix will prevent this from happening. We'll see.
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Post by Garf on Feb 16, 2008 21:42:47 GMT -7
I mounted this thing in my Galaxy to see what it does in the air. I'll try it tomorrow. The ground run has it going from a good setting, to lean, to rich thru the tank. Strange. Its almost like a heat/expansion problem.
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Post by Garf on Feb 17, 2008 12:39:48 GMT -7
Had 4 flights on the Brodak 40 today. First run, 10/10/10 fuel, 10-6 TF prop, started rich, leaned out after 30 seconds. After 3 minutes, started to sag. After another minute, it quit. Second run, 10-5 TF prop, 0/12.5/12.5 fuel, held a setting, low power. Third run, 10-5.5 graupner prop, 0/12.5/12.5 fuel, much better, more stable run. Fourth run, same prop, same fuel spiked with 1/2 oz 20% nitro, 20% castor fuel, a lot more power, but sagged half way thru flight. This thing has problems.
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jimp
New arrival
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Post by jimp on Feb 18, 2008 10:21:53 GMT -7
Saw this thread and it caused me to join up. Great site and I'm glad I found it. I have four B 40's and learned early on that you must, for sure, without fail follow the break in proceedures in the manual for good results. The nuts and bolts are 12 to 20 one to two minute stand runs in a 2-4 cycling run(let it warm up slightly lean) before attempting flight. Allow to cool to the touch. This allows the AAC construction to seat and mate properly. What we are looking for is heat, cool, and re heat. This will breakin much more consistently than a few long stand runs. Use at least half synthetic oil fuel. All castor is not good. After around an hour total time, the engine really reaches it's final break in and should be sweet beyond belief. Beyond that, it is a remarkable little engine capable of great breaking runs using some pitch in the prop or a steady two cycle run with less pitch, still making a very soft break in maneuvers. Some want more than it was perhaps designed for. It is best at under 600 inches in stunters at perhaps 46 oz or less and is a killer on Nobler/Oriental size ships. If you want to fly bigger airplanes it may disappoint you. Yep, I have some serious questions re: the Brodak needle valve assembly also. Wish they had done it as a one holer also. Glad to be aboard and thanks for the site. Jim
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Post by Garf on Feb 18, 2008 12:12:53 GMT -7
I tried the ST assy once. It did help some. The more I think about this, the more it could be this thing simply is not broken in yet. I only put 3 or 4 bench runs on it with straight castor fuel. I am trying to fly it now without the muffler. At first without the muffler, it would quit cold when it richened up in flight. After it came back from Tom, I installed his recommended plug. now it doesn't quit, not even with no nitro fuel. I'll probably put the muffler back on it for the next flights.
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Post by jehold66203 on Feb 18, 2008 14:41:30 GMT -7
Garf, if it is taking awhile to break in be glad. I was told years ago that the longer the break in the better the engine. I had engines that were flown at least 3 times every weekend and still needed more break in time. I usually run an engine on the bench long enough so it will run in the air and do lazy eights and loops plus inverted without getting hot. DOC Holliday
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Post by Garf on Feb 18, 2008 17:12:44 GMT -7
I believe GMA did the same thing.
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Post by Garf on Feb 24, 2008 12:41:41 GMT -7
I took the Brodak 40 out again today. First flight, started out a solid 4 stroke. At launch, it went into a 2 stroke and stood there. After a minute, it started to sag. after a while it crashed, broken prop. Second flight, started very rich. after about 15 laps it went lean and started to sag. after a few more laps, it went rich for the rest of the flight. I've about had it with this thing. I'm going to swap the brodak for an FP 35 and see what happens. If all is well, i'm going to dump the Brodak.
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Post by Garf on Mar 2, 2008 17:32:21 GMT -7
Tried the FP 35 today. First flight set slightly rich, leaned out during the flight and stood there. Second flight, set richer, at the end it was still a little rich. Either the Brodak 40 is bad, or the fuel tank is simply incompatible with the engine/plane combination. I have had that happen several times over the years. After the Brodak gets back from welding (again), i'll reinstall it and swap out the tank for another one, maybe a chicken hopper. If it still doesn't hold a setting, i'm going to put the Brodak thru a burn in process. Not much to lose as far as i'm concerned.
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jimp
New arrival
Posts: 11
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Post by jimp on Mar 5, 2008 11:03:19 GMT -7
A little strange but the overall problem seem to be that the Brodak is not fully broken in. The rich to lean, assuming a uniflow tank,suggests a leak. Anyway, the problem is fuel starvation/overheating obviously. I am fighting the rich to lean problem also with the Ringmaster 526/Brodak 40 combo. No tank leak that I can find in repeated checks. My next solution is adding a pressure tap to the Brodak muffler and trying muffler pressure. If that fails, will change tanks. The engine has performed well mounted inverted in a full fuselage ship but profile mounting is another story. Yes. it already has a supertigre needle valve assembly. Anyway, when you decide to go back to the Brodak, first be sure no trash in needle and filter is clean, then set it off so rich that it never breaks into a two stroke. Most B 40's seem to lean out a little when they hit the air. It appears that you are OK with no nitro and 25% oil, half castor so this might be a good way to continue the in air break in keeping it nice and rich-you should find the the B 40 makes a lot of power when in a dead 4 stroke with no break, assuming a good prop for that type run. Maybe after another 30 minutes or so, sneak in 5% nitro, same oil combo. A tank change might be the key also if the above fails. I think most important, try to get at least another hour's time on it in the air without it overheating. The overheat to the point of sagging is really not good. So bad, in fact, in my opinion that I will make every attempt to get it down immediately which is usually possible over grass. Interesting story in that with the Ring 526/B40 combo yesterday, I had the engine go leaner than I was comfortable with but not in a true melt down sag. Got in two touch and go's without killing the engine. On the final touch and go, I somehow forgot about my buddys lines on the circle and despite having 360 degrees of equally suitable dead grass and no wind, I managed to get it down in the 20 degrees or so of circle containing his lines. Net result: cost me a set of lines. The good news is that he wants to crimp them himself. Keep us posted. Jim
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Post by jehold66203 on Mar 5, 2008 18:58:00 GMT -7
Garf, if you truly can't get the Brodak 40 to work what would you take for it. I have an OS FP 35 I might swap for it. An aside on leaks you keep mentioning tanks. At the field last year my Ro-Jett 40 wouldn't hold a needle. We pressure checked tank by filling with fuel and looking for leaks. Even tried the needle valve assembly. Checked fuel lines and even replaced them. Found leaky metal fuel filter. Wrench and pair of pliers corrected the leak. Put up three more flights after setting needle back to normal. Later, DOC Holliday
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Post by Garf on Mar 5, 2008 22:00:53 GMT -7
I use the uniflo tank but I fly them capped for standard venting. What should happen is from rich to lean, but not back to rich again. If after a tank change, it still does the same thing, i'm going to put the Brodak thru a burn in process, similar to the Hi Johnson process. It won't be tight after I finish that.
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jimp
New arrival
Posts: 11
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Post by jimp on Mar 6, 2008 10:11:21 GMT -7
Tell us about the "burn in" proceedure. Not familier with it but sound ugly. Brodak says, and my observations support that break in is accomplished by numerous cycles of hot to cold, not so much total time on engine. This is why break in proceedure is 12 to 20 one minute stand runs of 1 to 2 minutes duration allowing engine to heat up nicely in a wet two cycle, then back to cool to touch. Actually, this is only a start as the complete break in usually takes another hour or so of flying time, allowing engine to go to full two cycle on ground, then backing off needle for hopefully a 4-2 breaking run in the air. After the hour or so total in air time, they get even sweeter in my observations. Jim
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Post by Garf on Mar 6, 2008 15:58:34 GMT -7
The "burn in" process is similar to the break in process for the hard cyllinder Johnson engines. Prop-tornado 12-4 cut to 7". Fuel, 5% nitro, 25% oil, mostly castor. Start the engine and bring up to full rpm, hold for 30 seconds then back the needle off until the slightest hint of richening. Maintain that for 5oz tank. Let cool. Repeat as necessary.
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jimp
New arrival
Posts: 11
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Post by jimp on Mar 6, 2008 17:22:36 GMT -7
Might do some good but see above re heating and cooling cycles. AAC engines are a different breed of cat from the old engines It would seem that the burn in method just lets the engine turn a brazilian RPM's but who knows. Would go light on the castor also, no more than half total oil. One regional flyer, competitive in expert class. Uses all synthetic, I think around 22% and gets cosistent nice runs from his Brodak 40. I still use half castor, 22% total, to maybe give some extra insurance from a melt down. Jim
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Post by Garf on Apr 3, 2008 10:47:50 GMT -7
I just got the Brodak 40 back from the welder. There is a pronounced bind in the engine when the piston is at the exhaust port. I'm going to bench run it, but its possible that the case is warped. Now i'm convinced this thing is cursed.
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Post by invisible on Apr 3, 2008 14:18:54 GMT -7
Wonder if the bind is in the case or in the liner, or both. If you take the liner out of the case and the bind is not there, then you might use some sandpaper on the inside of the case to get rid of the warp. If the bind is still there when the liner is free of the case, I don't know what to tell you.
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