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TT .28 issues ???
I'm new to glow engines, but I have had the help of an "old hand" in sorting this problem out. I flew my new TT .28 today on a SpadStik. She would start and run through transition easily enough, but any time she was tipped up, she'd die. My buddy made a number of adjustments and she seemed to be OK.
Of course, as soon as I had her up and flying...on a small rise in altitude, she died out again. I am going to re-route the fuel line so it stays more horizontal. Right now, the fuel line rises over the engine bulkhead and back down to the input fitting That rise is only about 3/4 of an inch. Could that be the issue? When she dies out, the fuel line is still FULL??? I noticed that she doesn't draw much in the way of fuel, as compared to my other engine. When I close off the intake port and hand crank the engine, the fuel doesn't rush forward, like it does on my other .46 engine.?? Additionally, my buddy noticed that we have oil coming out of the front bearings. Could this be a factor and what might I do about it? This engine has only been run a half dozen times on my bench, and now with two flights, it doesn't seem to be working very well. Any and all help appreciated. Thanks Rich p.s. I also own a OS .46 AX which display s none of these issues. |
RE: TT .28 issues ???
Try opening the HS needle valve a couple clicks
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RE: TT .28 issues ???
We did a lot of adjusting of the needle and the "air bleeder setting??". It seems that the TT doesn't use a high and a low needle like the OS. Anyhow, that is what we thought while on the field today. That is the only way we got her to fly at all..... then...poof..she still stopped running on the first climb. I just now re-routed the fuel line.
Any chance that the leaking front bearing is stealing "draw" power from the engine??? thanks Rich |
RE: TT .28 issues ???
ORIGINAL: w8ye Try opening the HS needle valve a couple clicks The air bleeder is not affecting the fuel while it goes from level to tilted. The air bleed is your low speed mixture. Make sure your "helper" understands air bleeds vesus low speed needles. They operate opposite of the Low Speed needles typical found on higher end engines. There is nothing wrong with them. My GP42 has one and it's a great running engine. w8ye has your answer above. Jack |
RE: TT .28 issues ???
Yep, you fellows have the solution. I opened it a lot more than " a couple of clicks" but....I found a spot where she liked to run and didn't stall out when I lifted the plane. If the winds slow down a bit, I'll give her another flight tomorrow. Thanks for all of your help. Rich
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RE: TT .28 issues ???
Hi!
Use a Tettra "bubbleless"tank and notice the difference! |
RE: TT .28 issues ???
Well, just readjusting the HS needle did the trick. She flew today and flew well, considering my lack of skill and the wind gusts. I still have some landing gear issues due to our rough field, but the motor and plane did well.
thanks again for the help. Rich |
RE: TT .28 issues ???
This is a great engine! I have one on a kick around plane; when you get the mixture and fuel lines corrected you will be happy with its performance.
Francis |
RE: TT .28 issues ???
Save me a trip to the TT4U site by telling me if this is a plain bearing or a ball bearing engine. My guess is plain bearing since the carb is equipped with an airbleed instead of a low speed needle.
Engines become better handlers as they accumulate running time. Fly the snot out of her, but keep that high speed mixture always rich of peak with the nose of the model pointed upwards by at least 45 degrees. Also try to run the smallest prop that the engine manufacturer recommends for your engine during break-in. It is good to keep the load of the prop low so that the engine will not overheat during the critical break-in period. I'm glad you are flying again. Have fun and good luck. Ed Cregger |
RE: TT .28 issues ???
Ed, It is a sleeve bearing engine, what makes this new design interesting is this engine has the carb cast as part of the case, along with a integral backplate mount, etc.
Here is a link http://www.thundertiger4u.com/thunde...8-p-13278.html |
RE: TT .28 issues ???
Incorporating integral carbs usually spells the coming end for a model engine manufacturer. I would not like to see that happen.
Folks have been making engines with separate carbs for many decades now. This desperate measure to relegate the engine to throw away status would have succeeded if it were not for one thing - the price. Ed Cregger |
RE: TT .28 issues ???
I have seen the carb and case get busted together. Perhaps it would be a little cheaper to replace them as a unit?
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RE: TT .28 issues ???
Does the TT .28 have a bushing in the crankcase?
Ed Cregger |
RE: TT .28 issues ???
ORIGINAL: richg99 I'm new to glow engines, but I have had the help of an "old hand" in sorting this problem out. I flew my new TT .28 today on a SpadStik. She would start and run through transition easily enough, but any time she was tipped up, she'd die. My buddy made a number of adjustments and she seemed to be OK. Of course, as soon as I had her up and flying...on a small rise in altitude, she died out again. I am going to re-route the fuel line so it stays more horizontal. Right now, the fuel line rises over the engine bulkhead and back down to the input fitting That rise is only about 3/4 of an inch. Could that be the issue? When she dies out, the fuel line is still FULL??? I noticed that she doesn't draw much in the way of fuel, as compared to my other engine. When I close off the intake port and hand crank the engine, the fuel doesn't rush forward, like it does on my other .46 engine?? Additionally, my buddy noticed that we have oil coming out of the front bearings. Could this be a factor and what might I do about it? This engine has only been run a half dozen times on my bench, and now with two flights, it doesn't seem to be working very well. Any and all help appreciated. Thanks, Rich P.s. I also own a OS.46AX, which exhibits none of these issues. I presume your engine is a Thunder Tiger .28GP. There is also a Pro version, but it is only available for ground vehicles (there isn't an airplane version). The GP does not have ball bearings, but it does have a bronze bushing in the crankcase, in which the crankshaft spins. In such engines it is quite natural for oil to leak out the front, behind the prop driver... If no leak forms, the oil clearance for the crankshaft is insufficient. Just ignore this issue, as it is not a problem. If you open the throttle and have the needle open 2 turns, fuel will rush into the engine, as you choke the carburettor and the air-bleed hole and turn the crankshaft over. This will also happen, in the same amount, if you plug the exhaust outlet and turn the crankshaft over... This is probably safer, BTW... A .46 engine, especially one with a two-needle carburettor, provides better suction... The fuel-tank mounting should be vibration isolated with ¼" latex foam. The tank should be as far forward as possible (without touching the firewall) and with its center-line must be at the same level as the center of the carburettor barrel. The pickup clunk must be at least ¼" from the back of the tank and free to 'fall' to the top of the tank, when the model is inverted. The pressure line must be open to the inside of the tank, with the other end connected to the muffler (make sure the nipple is open). The entire fuel-line must free of pin-holes and as short and as straight as possible... The means no 'slack' to ease refueling. The fuel system in its entirety, must be free from any debris, including the carburettor passages (debris/lint/hair in the carburettor's fuel jet, is one thing that can cause problems you are having). The engine must be adjusted to run consistently at full-throttle, with the nose straight-up. If it sags, or leans out, it is set too lean! The air-bleed idle mixture adjustment, must be done for best transition; from a steady idle to full power, in level-flight attitude. Screw it in to richen, out to lean the low-end mixture. There are not 'buts', no 'ifs' and no excuses... If you do just one of the above wrong, your engine will not run right; and one thing cannot 'compensate' for another. And your engine has a gender... it is a neutral 'it', rather than a 'she', or a 'he'... It has absolutely no mind of its own and the quality of its running, is totally dependent upon your installation and your adjustment skills... If the engine quits on you, too far away, you can't blame that 'old hand'; only yourself. So, you had better perfect them all, so your engine will run well; not lousy. |
RE: TT .28 issues ???
Thanks, SHE is running just fine now with the help posted on the 2nd answer above. Yes, running her a couple of turns out was the answer that I needed. I will file your response for future reference, though. Thanks for the detailed help. regards, Rich
p.s. if boats are called "she"....(which they have been for centuries) I believe that they perform better. Mine certainly always have. Probably true for airplanes and engines, too. Ha ha RG |
RE: TT .28 issues ???
ORIGINAL: richg99 Thanks, SHE is running just fine now with the help posted on the 2nd answer above. Yes, running her a couple of turns out was the answer that I needed. I will file your response for future reference, though. Thanks for the detailed help. regards, Rich p.s. if boats are called "she"....(which they have been for centuries) I believe that they perform better. Mine certainly always have. Probably true for airplanes and engines, too. Ha ha RG I am glad you got your engine running well... As someone new to this, you can learn from what I had written. As to ships and maybe planes being called 'she'... at least they can move under their own power (or sails) and go places... Using 'she' for your plane's engine would be similar to calling you plane's left wing; 'Michael'... |
RE: TT .28 issues ???
OK I'll concede that naming an engine is a stretch....but boats and planes need names. How else can I cuss them out when they don't behave my erratic commands? Ha ha regards, Rich
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RE: TT .28 issues ???
Engines breath, therefore they live. ;):D
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RE: TT .28 issues ???
You're lucky for resembling Ernest Borgnine. I resemble the baby buzzard in the Warner Bros. cartoons. "I'm lookin' for a baby bumblebee..."
Hmm. That might make a great avatar for me. Ed Cregger |
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