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About Petehdgs

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    Culpeper VA KCJR
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    M20E Super 21

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  1. Thanks for the kind words. Bob, what kind of cowling is on the front of your bird? It looks similar to stock but with smaller air inlet holes. Can it be added without much fuss? Or is it a 70 hour install? Does it improve airspeed or climb? You have my attention! Just so you all know I'm not much on cruising through message boards except when they show up in searches about things I am curious about. If you come across something that you think I might interest me give me a shout. I might not answer right away but if it is interesting I'll be sure to take a look.
  2. >>> Welcome aboard, and best regards, >>> Thank, you Carusoam >>>What brings you to visit MS? Looking for a faster, more efficient bird?>>> I initially joined when I was looking for a better bird. I owned a '68 Cherokee 140 from 6/04 to 12/17 13.5 years. It took about 6 months without my own bird to realize I really needed my own bird again. So I started looking and comparing models and based on the flying I do, and want to do in the future. That includes some grass field work and possibly mountain flying for a trip to Utah or Alaska or Canada. I sought out and bought a '64 E model about 6 months ago in part because it is the best short field Mooney and in part because it can be reasonably priced to purchase, own, and maintain. My bird a really nice example of the type and is basically a legacy aircraft with some speed mods. The fact that it is all mechanical with steam gauges suits me perfectly. I love it. I had forgotten that I signed up here until I started researching the PFE exhaust system for my bird. >>>Note: To keep an eye on my fuel level... I use a flow meter and totalizer, backed up with fuel level gauges, and another set of fuel level gauges for another level of back-up...>>> Right now I do not own a fuel flow meter and have not owned one. I understand their usefulness, especially in airplane operations, but I am frugal and can get the same information through other means. I am not saying I wouldn't spend the money to buy one in the future, but it is not high on my list because of cost vs benefit to me. >>>>>1) does the PFM work as advertised on the Mooneys, or not? (So many details beyond the theory...) >>> I can't say from personal experience at this time, but they have published data that can be duplicated in the field, and their claims are not unreasonable. I would say that they are likely to perform as advertised and they have a 60 day return policy (parts only no labor) to back it up. As long as you understand the gains are small, and not likely to pay for themselves in fuel savings alone then my short answer is yes. >>> 2) Do I need to fully understand what an exhaust header is supposed to do? Or why it does it? >>> Yes and no. Airplane ownership and maintenance involves making informed decisions as to how best to spend your hard earned money on your own airplane. Most people don't know too much about exhaust systems and that is normal. Years ago I read an article in HotRod that asked the simple question: If I buy this muffler for $40 or that muffler for $90 what do I get for my extra 50 bucks? That sounds a lot like the same questions raised here in this topic. HotRod based an article on that question and used a chassis dyno to power test 6 different mufflers that were popular at the time. That is the first article that introduced me to the complexities of exhaust systems. Do you need to know all that to maintain your airplane? No. Do you need a good working understanding of what you are buying or not buying if you are considering new equipment for your airplane? I say YES. If you have to replace your exhaust anyway, then the labor part of the cost is the same. If a new stock system is $2000 and a new PFE is $4000, you are going to spend $2000 anyway (or $1800 or $1500 depending on cost at the time). That means the upgrade is really only $2000 instead of $4000 because you would have spent $2000 anyway. But the PFE is supposed to be the last exhaust you will need to buy. It all boils down to personal choice and cost vs benefit, and to make an informed decision you need to know what you are buying or not buying. >>>3) Let’s assume for a moment, I understand the thermodynamics of internal combustion engines used in my Mooney... >>> >>>4) There are quite a few MSer’s that will be reading this thread.... Let’s assume for the moment, they don’t feel insulted when they are told they may not fully understand... >>> Not an insult, just an observation based on the contents of the posts. There is no shame in not knowing everything in aviation. No one person can know it all, least of all me. >>>5) If we have the required AMUs, and want to spend them... will we see the performance improvements or are they fictional creative writing exercises by the PFM marketing team, foisted upon the unknowing aviators..? >>> I am not sure what an AMU is. The rest of the question is a legitimate concern. Do they work or are they trying to blow smoke up your A##? Even if their claims are true, the improvements are very small and may not be readily apparent to some owners and pilots. Want to climb better? Simply fly on cooler days! If you test the stock system in 40F weather and test the PFE in 60F weather you may not notice anything at all. That is because the gains are small enough that a change in weather on the testing days may make the improvements appear to vanish. In the industrial engine business engine performance is guaranteed at at a certain air temperature and altitude. Hotter today? Not as much power is produced. Colder today? I've got me a little hot rod. I truthfully can't tell you the performance improvement claims are real. I can tell you they did their best to provide data that can be repeated. That alone should say they are real... but small. >>>6) Often, The PFM is being considered as a replacement for the original hardware... and comparisons are being considered... fit, finish, maintenance issues, does the heat still work... all important issues... >>> I agree >>>7) If the PFM works so well at removing exhaust gasses, because of its brilliant design...does the exhaust expand so quickly under low atmospheric pressure, that the EGT becomes colder, and residence time is minimized....does the EGT drop too fast to allow adequate heat transfer to occur..? >>> The working fluid in an internal combustion engine is air in its various forms. Air, Air and Fuel, Air and Fuel on FIRE, and Air as spent HOT exhaust gasses. Air and fuel has mass, and connot be stopped or started instantaneously. The work that is being done here is to use the energy in the exhaust during the valve overlap period to help start the flow of intake air into the cylinder as the intake valve opens, before the movement of the piston is actively pulling the air in, thus displacing the remaining exhaust gasses into the exhaust system. This is where the timing of the exhaust pulses causes a suction on top of the piston to help pull the intake air into the cylinder as the intake valve just opens. The suction pulls more of the spent gasses out due to lower pressure near TDC, and the lower pressure helps suck out the intake air, which is stationary next to the valve, at the instant it begins to open. Once the intake charge is moving and the exhaust valve closes that work is done. The reduction in EGT is mostly a result of less preheating of the intake air fuel charge on top of the piston because less of the hot exhaust gasses are present. The increase in power comes from more overall air and fuel entering the cylinder, thus increasing volumetric efficiency. My previous calculations were 8% more power (more air), and 1.56% better efficiency (less fuel burned at the same power output). I hope that answers most of your questions. I am out of time right now.
  3. After reading this thread it appears to me that some of you may not fully understand what an exhaust header is supposed to do and why. Tuned exhaust headers are designed to use the explosive kinetic energy of the spent exhaust gasses to pull a vacuum on the exhaust port as the piston is approaching TDC on the exhaust stroke. While the piston is moving through TDC and is very close to the top of its stroke, the exhaust valve is closing as the intake valve is opening. Several degrees before TDC the intake valve begins to open, several degrees after TDC the exhaust valve becomes fully closed. During this short time of valve overlap both valves are partly open and the piston is very close to the head, leaving the small exposed volume of the combustion chamber open to the “wind” formed by the moving intake and exhaust gasses. This wind can move backwards through the engine if there is back pressure in the exhaust or vacuum in the intake manifold during the valve overlap period. The diameter and length of the header tubes, collector, and output pipe work together to harness the momentum of the exhaust gasses and pull on the exhaust port as the piston nears TDC and the flow of gasses leaving the cylinder slows. Depending on valve timing and other factors, these forces could be powerful enough to pull some intake mixture clean through the combustion chamber and into the exhaust manifold. At first header pipes were designed mostly by trial and error. Later a series of manometers were connected through a timed distributor to a sensing port close to the head. 12 Manometers tied to the engine at 5-degree intervals could show the port pressures from 30 degrees before to 30 degrees after TDC, giving the designer a better look at what affects the headers were actually providing. These days modern computer programs can simulate the filling and emptying cycles of an engine with a high degree of accuracy, provided correct information about the various engine parameters are applied. This includes bore, stroke, RPM, bearing friction, ring friction, parasitic loads, valve diameter, valve lift, timing and lift profile, intake runner length, diameter and type, exhaust runner length and type, carburetion, octane rating, fuel ratio, ignition timing, and atmospheric conditions including temp, altitude, and barometric pressure. An engine designer or modifier with a computer now has a tremendous tool available to get most of the trial and error bugs worked out before welding up pipes and adding them to the engine. I have experimented with these computer programs and they can be a lot of fun as well as enlightening as to how engines move air and produce usable power. There is another aspect to all of this to consider. Engine and airplane manufactures have known for decades that intake and exhaust systems can improve or retard engine performance. Therefore, lower performance machines will likely have quieter and more restrictive exhaust systems, whereas higher performance machines will likely have louder and less restrictive exhaust systems. That means there is less potential for improvement on the higher performance machines with less restrictive exhaust systems than there is on the lower performance machines with more restrictive exhaust systems. However, the lower performance engines are also likely to have less aggressive valve timing and lift profiles, thus limiting how much improvement can actually be realized. This is one reason why performance increases are likely to be small. If you are racing cars and a small improvement let's you beat the competition and win some races, then all the effort is worth the cost. Not racing? Then maybe not. Fortunately there are other tangible advantages like improved takeoff, initial climb, better climb at high altitude, and higher service ceiling. These other improvements are also likely to be small. The components are of high quality and designed to last for the airplane's lifetime, so the PFE is and premium upgrade not just a replacement exhaust. Is all this worth it to you? Only you can decide that. Now let’s look at some of the performance numbers from Powerflow. There is a link to the performance charts at the bottom of their web pages for the M20C 180HP and M20EFJ 200HP machines. These files show stock TAS and fuel flow vs PFE modified TAS and fuel flow at 2500, 5000, 7500, and 11500 feet and at different RPM settings. In nearly every case there is a slight speed gain and a slight fuel flow increase. Most readings are taken from 50°F ROP and WOT or as specified, meaning that the data could be duplicated if necessary. For example, M20E at 7500 MSL 2500 RPM WOT 50°F ROP tested 153 KTAS at 11.0 GPH with the stock exhaust. With the PFE it tested 159 KTAS and 11.7 GPH. What would the fuel burn be back at 153 KTAS with the PFE? By reducing RPM to get back to 153 KTAS the fuel burn would be 153 / 159 (Squared) x 11.7 = 10.83 GPH. That number might not be perfect, but it is pretty close by my estimates. I admit that is not a lot of fuel savings, but it takes the same HP to drive 153 KTAS with either system, so the PFE is actively improving engine efficiency by about 1.56%. The 50°F ROP engine is thus more efficient at the same power output, and making that same amount of power at a lower RPM. At 159 KTAS vs 153 KTAS the engine is producing about 8% more power to do so. 159/153 TAS (squared) = 1.07997. 11.70/10.83 = 1.080. In a cruising airplane the fuel burn and HP required varies with the square in the change in true airspeed unless the drag profile is changed by adding weight or changing the configuration. That means you can use your airspeed indicator to indicate fuel flow, like a poor man’s fuel flow meter. If you want to learn more about how engines and computer simulation software works, get a copy of Desktop Dynos from ebay. It is old book but very informative. If you want to learn how to use your ASI to indicate fuel flow then read my article in Air Facts Journal and apply that to the charts in your POH. I made a quick reference chart that is easy to use while flying. Have FUN! Fly Safe!! Petehdgs Powerflow M20C180.pdf Powerflow M20J200.pdf
  4. The Lift AOA system is very similar to the older Lift Reserve Indicator. The owner of Lift Management redesigned the Lift system probe to be easier to install and to adjust than the probe used on the LRI system. Other than that the two systems operate the same. They are fully self contained and require no power from any existing aircraft systems. Last December, I sold my '68 Cherokee 140 after owning and flying it for 13 1/2 years. I had installed an LRI in the panel back in 2007 and flew with it for about 10 years. I trained hard with it and learned a lot about flying and about my aircraft as well. It is definitely worth having, but you must train with it to fully understand it and what it can do for you. It is also a lot of fun to play with your aircraft at minimum flying speed utilizing maximum AOA without going over the limit. This is exactly what the Wright brothers did to teach themselves and the rest of the world how to fly. The only instrument on the early Wright flyers was an AOA indication. Right now I am in the process of purchasing a '64 Mooney E Super 21. I have bought Lift AOA system to install on it and am looking forward to using it on my new (to me) bird. Read the last comment by me about using the LRI in N5586F UPDATE 3/12/19: I have owned my Super 21 for six months and have logged about 40 hours so far. I have installed the Lift Indicator and set the needle at the bottom of the green at the best angle of climb. The Mooney behaves much differently then my Cherokee. The numbers are right much closer on the Mooney and the mush falls off rather quickly, meaning there is not much bottom performance to be gained like there was in the Cherokee. I do find I can climb right much steeper with the lift indicator simply because I can hold the right AOA as the aircraft accelerates and it climbs quickly and steeply as as it accelerates out of ground effect. The best way for me is to rotate in the white and hold the climb at best AOA as the needle rises and the airplane accelerates. I then raise the gear after the steep climb is established. With single pilot and full fuel on a cool day, things are happening too fast to lift the gear before establishing the steep climb. On a hotter day and with more weight on board this method may need adjustment. But for now, I have me a little hot rod!