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Everything posted by Shadrach
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Indeed. Do understand that in order to be LOP at 16.5gph you will need to run higher MP than the book 75% ROP MP setting.
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I never have figured out why the Owner’s manual says that. Every system that I have encountered is precisely 4 pumps IF the system is fully bled.
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Your engine has a compression ratio of 7.5:1 which makes it less thermally efficient. For that reason, the multiplier/divisor is 13.7 instead of 14.9.
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It’s not that simple. At Max FF of 33gph a significant portion of that fuel is going out the exhaust as unburned hydrocarbons. That surplus fuel is used to slow the combustion event. For your engine, 75% LOP fuel flow would be ~16.5gph. I cannot stress enough that a TSIO520 is a power plant that requires a thoughtful and conservative approach.
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How many times do you want this verified? By how many people? Reread the thread and you will see a number of confirmations and the reasoning behind them. I'm not sure what else can be said. If you're really uncomfortable, maybe you should seek someone local that you trust or stick to the published POH power settings.
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You are full of opinions about operations that you’ve never conducted and data that you’ve never seen
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Is the actuator leaking or weeping? The vent hole at the bottom of the cylinder will weep a tiny amount of fluid over time. LASAR sells an overhaul kit for the actuator, but I’m sure the parts could be sourced locally. Several years ago I noticed a leak at the actuator. I took it apart but there was no evidence of a problem. I cleaned and reassembled everything and it’s been tight ever since. A piece of FOD must have entered the system.
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Any idea what caused it? I’ve seen a number of detonation issues over the years. 0% of them were attributable to LOP operations.
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Flaps should be totally hydrolocked after four pumps. More than that and there is air in the system. I made a short video so folks have a reference for how they should perform when properly set up.
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It’s clear to me that it matters no number of factory power graphs, annotations, accompanying explanations and references will be sufficient to change your misperceptions and that is fine by me. No one has ever asked you to operate your plane outside of how you see fit. I just wish you would stop stating your opinions as facts (especially with no supporting data). When someone posts a question about engine operations they are typically looking for something more in-depth than, “you don’t need some fancy engine monitor to run LOP. Just run at less than 60% like me. I’m risk averse and you should be to because your engine will self destruct if you run more aggressively than I do and anyway there is no such thing as high power LOP and if there is you’ll shoot your eye out trying and…” How many pilots do you think have harmed their engines in the last several years incorrectly operating LOP?
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The original calculations were APS numbers. Then someone created a CSV file that extrapolated multipliers for all compression ratios with an HP calculator (available here in the downloads section). Mathematically trying to differentiate between the the 14.89 used for 8.5:1 CR and the 15.13 used for our 8.7:1 CR Lycomings is like measuring two cubes of jello with a micrometer.
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Without pictures it’s hard to tell. However, I would say that there are scenarios where an initial, high grit, wet sanding makes more sense than starting with polish. Yes it’s more aggressive but in my opinion it’s also easier to be methodical and consistent.
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1) Remove the B-nut and plastic cover from the T shaped AN fitting on the ACTUATOR (lowest point in the system) and attach a pressure pot filled with the hydraulic fluid. 2) Ensure that the small lever is in the "flaps up" position (this is to say needle valve off the cam lobe that opens the check valve). 3) Attach an AN fitting with a 2' hose to the reservoir to act as an overflow. position the hose over a catch can (bucket). 4) Actuate the pressure pot and watch for fluid at the overflow hose at the front of the aircraft. 5) When you detect fluid coming through the overflow, cut the pressure from the the pressure pot. 6) Plug overflow hose and reservoir vent. 7) This is where it gets messy... remove pressure pot fitting and replace the blocking plate. 8) Remove whatever you used to block the reservoir vent plug (I've used chewing gum). Leave the overflow plug in place. 9) Select "down" position on flap lever and have someone simultaneously pump the the handle (slowly) while you back off the plastic plate on the aforementioned actuator "T fitting" just enough to allow it to leak. You should get fluid only, but possibly a small amount of air and then fluid. Have your pump person maintain gentle pressure. Make sure to only have the bottom of the system open under positive pressure from the pump person. Close it under pressure. If the person pulls up on the flap pump and the system is open it will draw air into the system... 10) With T fitting secure, pump the flaps down. Remove overflow hose, retract flaps and be ready with a rag to catch any overflow. If fluid level is too high in the reservoir , siphon a bit off with a drinking straw (use your thumb not your mouth). 11) close up the system, adjust flap retraction speed set screw so that the flaps take apprx 10 secs to retract, ops check, button everything up and go fly... The above process usually works. on occasion the pump cylinder will not draw in fluid. If that happens, it may be necessary to pre-prime the pump.
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I’ve seen 15.XX used but we’re in “angels dancing on the head of a pin” territory. Friction losses are a consideration but one must also consider that the transfer of force (mechanical advantage) to the crank varies throughout the power stroke, and that those variations of pressure during the power stroke will differ with changes in RPM. 15 is a good round number that’s close enough. Operating above 75% LOP (FF above 10gph) is not dangerous. If one has an engine monitor, it’s very easy to demonstrate why, but you must be at low altitude on a cool, high pressure day . You simply set book manifold pressure and rpm for 75% power at 100 ROP, and wait to observe steady state CHT‘s. Then reset the mixture on the lean side at wide open throttle. What will be observed is that 75% on the lean side yields lower CHT’s. And indeed more than 75% also yields lower CHT’s all other things being equal. This is a repeatable observation. At 1500msl on a cold day I can fly as fast or faster on less fuel with lower CHTs on the lean side. It’s coming up on the time of year here in the mid Atlantic where flying at 4500MSL might equate to a DA of 1100 feet. Under those circumstances it makes good practical sense to set mixture for the highest power possible on the lean side. Especially if you’re traveling westbound and will have to deal with high winds at higher altitude. This gives the operator the ability to fly low while enjoying a fuel burn that mirrors high altitude ROP operations coupled with a high TAS that yields optimal GS by staying below the strongest winds. Unfortunately, mixture setting can’t improve the ride down low when it’s bumpy.
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See my post above. If the numbers you posted are accurate, your engine was in a very happy and conservative place. Running closer to peak and pushing all of your CHT‘s into the low 300s would be equally efficient from a BSFC standpoint and slightly faster with no detriment to cylinder longevity.
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Detonation is a function of peak internal cylinder pressure. Mixture affects internal cylinder pressure but suggesting that it’s the primary driver muddies the water. Ignition timing, temperature and piston speed, are all contributing factors. Precisely defining the “red box” in its entirety is not really possible for practical reasons. One would have to set subjective metrics on each side of the box and the edges would vary based on conditions. It is however, easy to define the center of the red box. It is the fuel/air ratio for a given RPM that produces the most rapidly propagating flame front which in turn produces the highest PEAK internal cylinder pressure and thereby the highest CHT. Typically ~40ROP. Small changes in mixture from that point either richer or leaner make only small differences in flame front propagation and peak ICP. At some point beyond those small changes, propagation and peak pressure start to decrease significantly (relatively speaking). At some from peak ICP, going leaner generates a somewhat more rapid decrease than the corresponding point on the rich side. The Lycoming graph I posted earlier presents a clear, conceptual picture of the spectrum. The center of the red box (highest peak pressure) is depicted in the graph as the top of the CHT curve (hottest point). From an internal cylinder pressure standpoint, at any manifold pressure, peak EGT or leaner is more conservative than 100° ROP. By ~50° LOP, The engine is getting to a place that’s more conservative than 250° ROP. However, it’s difficult to make direct comparisons. CHT (all other things being equal ) is more a function of peak ICP than mean ICP. Power is a function of MEAN pressure produced during the power stroke. The slower nature of LOP flame front propagation can produce equal (or higher) mean pressures with lower peak pressure. Sort of the difference between a hammer blow at the top of the power stroke (ROP) and a constant push (LOP). EDIT: Hat tip to @bluehighwayflyer for catching a ROP/LOP typo. Correction made.
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CHTs in the high 200s/low 300s at an OAT of 40° are not “Redbox” numbers. It’s prudent to pay attention to the actual feedback from the engine, rather than generalized, one size fits all, theoretical recommendations. Here’s a controversial statement based on decades of operating a normally aspirated IO360 - The “Redbox“ does not extend into the lean side of the mixture spectrum for a Lycoming IO360. Its borders, while fuzzy, are located solely on the rich side of peak EGT.
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Looks like I got burned by the interwebs. Before posting, I did an image search of the TSIO360-MB1 and this turned up. My mistake.
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I’m not saying it’s impossible, but highly unlikely to get an approval to move to a new category. And if you were able to it would likely be for flight testing purposes only so no passengers or travel.
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That is a conservative setting (just under 70%). If your CHTs are only 240° Higher than the OAT of 40°, your engine is not stressed.
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For the op of this thread, this is not an issue as injected, Lycoming, 4 cylinders typically have excellent fuel/air distribution out of the box. Regarding the K model, the stock injectors in your TSIO360 MB1 likely flowed very evenly and precisely. The intake manifold is the problem and necessitates uneven injector flow to create even fuel air ratios. The “three holed flute” design of the intake allows fuel to migrate from one cylinder to the next, causing a progressively richer mixture. The reason most Lycomings run LOP well in stock configuration is because fuel cannot migrate from one intake tube to another like it does with the Continental. EDIT: it looks like my assumptions about the TSIO360-MB1 intake design were incorrect. However it stands true for the TSIO360-LB and GB suffix engines.
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It looks like you are referring to me without actually referencing me. Nothing I do with my engine requires that I am “really paying attention” anymore than I would be “really paying attention” operating any other way. I try to pay attention to my engine on every flight, especially in critical phases. I think that if one operates with a minimal amount of instrumentation, one would naturally wish to operate very conservatively. I too operate very conservatively. I just use temperature instead %power of as a proxy for internal cylinder pressure and engine health. If you can outline a scenario in which my engine is stressed when the highest CHT is <340…during a mid Atlantic August…I’m all ears. It also seems there is some confusion about how detonation typicall manifests with regards to mixture (to be clear, detonation is nearly impossible to induce in a NA Lycoming). The order of operations for mixture induced detonation typically starts with pressure from a rapidly propagating combustion event that occurs close to TDC. This makes for excessive peak internal cylinder pressure (ICP). As a result, CHT’s begin to elevate. If nothing is done to reduce ICP, CHT will continue an ever more rapid increase. Detonation will begin at some combination of elevated CHT and high internal pressure. The severity of the detonation and how long it is allowed to continue will determine if permanent and/or catastrophic failure will occur . Yes there are scenarios where detonation can be induced by pressure alone, but none that realistically apply to a normally aspirated Lycoming. Another thing that should be made clear. It would require idiotic levels of abuse to get a normally aspirated Lycoming to detonate even while in the “red box”… to get it to detonate with all cylinders on the lean side of peak would be damn near impossible. Operating on the lean side of peak above 65% is not dangerous, it’s not cavalier and it’s certainly not difficult…nor does it require special attention. It simply requires that one verify they are operating a well conforming engine (which is almost all stock, 4 cyl Lycs) and that one has a way to discern that the mixture on all cylinders is beyond peak. I could do this in my plane with the mixture knob and the airspeed indicator and be adequately precise. However, it’s much nicer to have engine data, especially when you’re learning. LOP operations are not riskier than ROP operations, nor are the margins thinner. If you look at Lycoming’s own graph, it shows CHT at peak EGT being roughly equal to CHT at ~130ROP. While the graph is conceptual, my real world experience after flying a well instrumented Lycoming for 20 years is that it’s a realistic representation of what can be duplicated in the field. If anything, peak (on richest cylinder) is more conservative than 130ROP (leanest cylinder). Detonation is just not the risk that it’s being portrayed as on the lean side of peak. Indeed there is almost no scenario where CHTS climb after peak, much less detonate. Many Pilots want to know more about their power plants and how they perform. They install engine monitors so they have access to real time data to use in pursuit of maximizing efficiency, speed and longevity. I’m pretty sure almost none of them instrumented their engines so that they could just set it at 60%. It’s fine advice for someone who doesn’t know what they don’t know. People don’t take cooking classes to learn how to pour cereal into a bowl. These threads are about optimal operation not just adequate. Moreover, the genesis of this thread centered on NA Lycoming ops. For TSIO engines, there are additional operational factors, considerations and risks as there are for TN’d engines. While the concepts, physics and chemistry are the same, I think blending NA and Turbo engine operations into one thread is suboptimal. For those of you that wish to learn something interesting about your engine. Record your CHTs at a full rich power setting in level flight and then (all other things remaining equal) pull to the lean side and see what LOP setting approximates the same CHTs as full rich. Those of you that have never tried this will likely be surprised at how close to peak on the lean side the engine will be to produce the same CHT as full rich.
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That OWT is spread here on a regular basis. Theoretically it is safe to run at an power level on the lean side, provided there is sufficient air available to maintain an adequately lean FA ratio at the FF needed for 100% power (just as its safe to run 100% ROP provided there’s an adequate surplus of fuel). It’s not practically possible for a number of reasons, but some TN applications can get close. I run in excess of 80% LOP when cruising at low altitudes. Another OWT is that “peak” is an abusive mixture setting. I have determined through testing that for my power plant, peak EGT (richest cylinder) produces about the same or slightly cooler CHTs than 100ROP, all other things being equal. Peak is the intersection of max power and max BSFC and is an excellent choice for cruising at DA’s between ~5,000 and 12,000. Peak makes for the best heater output in winter, but only by a small margin.
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XeVision® XeTREME™ LED LANDING LIGHT (par-36/46)
Shadrach replied to 201Steve's topic in General Mooney Talk
FYI. If it will fit the early J cowing, it will likely fit the vintage A, B, C, D, E, F and G models. These models all utilize PAR 46 bulbs mounted in roughly the same location. -
‘67 F Airspeed Indicator, Need to OH or Replace
Shadrach replied to gwav8or's topic in Vintage Mooneys (pre-J models)
Porter-Strait is in Tulsa https://www.porterstrait.com as an added bonus they also work on Brittain instruments