testwest

Great discussions. I never come off WOT until pattern entry or approach, either. For intermediate level offs I just let it accelerate. Typically the controller is trying to increase lateral spacing from some other traffic conflict to let you climb.. so the faster you go while leveled off, the quicker the conflict resolves and they then issue a higher altitude.

Thanks! More to come, I am going to post more a bit later!

So, my use of the term Vz is titled "Best Efficiency of Climb". The cruise speed Vz postulated by Brent Silver never really caught on in the vernacular....and the reason I chose Vz is it is easy to remember Vx is best angle Vy is best rate Vz is best efficiency. Graphically those ideas could be simply presented in a drawing of an airplane climbing very steep for best angle, a little less steep for best rate and a little less steep again for best efficiency. Vz is 1.32 times the published max gross weight sea level standard day indicated airspeed Vy as shown in the POH. No need to adjust the speed for gross weight, cg or density altitude. All of those variables fall out in one easy-to-remember performance limit, which is 500 feet per minute rate of climb. For the M20J, climb at 115 KIAS, WOT, Target EGT, cowl flaps as needed for CHT less than 380 deg F. When performance drops to 500 fpm climb, transition to constant 500 fpm climb until speed decreases to Vy, then maintain Vy.

Dave, well done handling a really bad situation. If you have your parts manual you will note that bolt (a machine screw, actually) is supposed to be an NAS222-13....but this hardware nomenclature has been superseded, the new part is MS27039-1-13, available here: http://www.aircraftspruce.com/catalog/hapages/MS27039.php?clickkey=3770 , they are $0.15 each. Bob is right, those seats take a beating. But the substitution of an all-thread screw because someone way before FlyDave got stymied on the old part designation did not help, either. The information I show here was found in under 5 minutes of Google use.

Hi everyone I am presenting the Vz paper to a regional symposium of the Society of Experimental Test Pilots this Friday in San Diego. I would love to hear any feedback from anyone who has adopted this climb profile and uses it on a regular basis. Thanks!

Bumping this up to the top to refresh the thread, and to support another post.

Benchmark runs under the Mac OS, currently OS10.* something or other, named after a large cat. It does not run under iOS like on the iPads. That may be a future development of Benchmark, but such development isn't currently driven by any financial motivation.

Sure! 1. You are going to need a Mac. No way around it. I bought a MacBook Air just for this program, and it has become my favorite laptop by far. I run Parallels and Win7 anytime I need that environment for other programs, like JPI EZTrends. 2. Download the program free, here: http://www.seqair.com/benchmark/index.html There is a MASSIVE amount of information on this website on how to run Benchmark. Be sure to read through all of it before you contact the software author. 3. You can perform flight tests for your airplane's performance, or input the perf data from the POH like I did. 4. Have fun!

So, this is one of those questions that Benchmark is tailor-made to answer. Let's put an M20J at 8000 feet, best power, WOT and RPM pulled back to 2400. You are making 135 hp at 11.1 gph or so. Here is a graph of a McCauley C212 under those conditions: Note the thrust horsepower is about 118 hp. Now consider running LOP to get the same power, it takes about 2550 RPM, 9.2 gph and you are still going about 155 knots or so. Note the thrust horsepower is exactly the same. Remember, you are much better off picking at altitude where your CAFE parameter is maximized for the wind and route. If you like WOTLOP and 2400 for cruise, just put those numbers into the fltplan.com advanced burn profile and then run the wind matrix button off the flight log page. It's really handy, and it's free.

That is true. It sounds like you have everything quite well dialed in. I would make the center electrode resistance test part of your regular spark plug maintenance regimen. It remains to be seen if back-to-back comparisons of Champion massives versus Tempest fines make any difference in GAMI spread or overall specific fuel consumption. Any difference would be pretty hard to sort out, more than likely.

For Doc, if you are running well now, no need to change. Check your center resistance at the next scheduled plug service. Above 5000k ohms, may want to replace. Fines may or may not increase efficiency a very small amount. RAM says yes, TAT says maybe not. I would use them on a boosted engine, but on an NA only if you don't mind the extra cost.....

This is one awesome discussion! I think we got most of the points......Carson's Speed for the M20J is 115 KIAS, or 113 KCAS. This is for sea-level standard day conditions, and remember at these conditions you have about 2 knots of position error, so your ASI reads about 2 knots high, assuming no instrument error. Vy (and by implication, Carson's Speed), decreases with altitude a little bit. However, the magnitude of the decrease for altitude, or changes for gross weight and temperature are not huge. Trying to keep track of all these little differences is bread and butter for a piston airplane performance engineer, but unlikely to be rigorously applied by a "usual and ordinary" pilot. That's why the Vz profile uses the published sea level standard day Vy as the starting condition. Weight, temperature, engine not quite putting out 100%, all that stuff falls out to the 500 FPM performance limit in the profile. So the technique becomes very effective, while being easy to apply every day and insensitive enough to the actual precision of a pilot's flying technique to remain viable. I ran sensitivity analyses for all of those conditions during the thesis work. For cruise, the parameters of interest are velocity made good, and mpg. This means winds are an overriding factor in cruise efficiency as measured by the CAFE score. What I have done is put the Vz climb profile and my 65% LOP cruise speeds and fuel flow into the advanced performance profile on fltplan.com ...and I use the wind matrix to predict the altitude which yields the best CAFE score. Your choice of altitude to maximize your 65% LOP cruise CAFE scores is how you get the balanced CAFE efficiency out of these airplanes day after day. Down low you may be at 2200 RPM WOT into a headwind, and up high you may be 2600 to make that 65%. You may be slightly better off going 70% power LOP into a headwind, but doing a 2 variable condition wind optimization (altitude and LOP power) is beyond anyone's capability to model at this point.

You guys know all about the Champion problem with increasing resistance on the center electrode, right? Lots of material here on that.

Very interesting, indeed. I have not done a sensitivity analysis on LOP climb for Vz, however the very stark increase in prop efficiency and lower drag factors (not speed, obviously, but less cooling drag from wide-open cowl flaps and less drag induced from counteracting sidewash) while on the Vz profile tells me choice of climb speed is far more important than using an LOP climb versus a Target EGT ROP climb. Still waiting for aaronk25's flight test report.

Peter, if you wind up losing the ability to make pressure after replacing the o-rings and servicing the fluid in a short period of time down the road, it is definitely time to replace that master cylinder. This happened to us, we kept losing one of the brakes, the master cylinder o-rings were replaced, it would work for awhile, then fail again. Once the master cylinder was pulled out, scoring marks were easily seen in the barrel, which were prematurely failing the o-rings. One new master cylinder, problem gone. If you service the brake fluid yourself, a pressure pot with a good bit of 5606 is helpful. The brake line has a high point in the wheel well and I am pretty sure one could trap an air bubble in there, leading to the spongy brake feel. Pushing in a bunch of fluid "should" alleviate that problem. If you have a cooperative AMT, you can do a lot of this yourself. It is messy work, but you certainly gain a better knowledge of your airplane by wrenching on it.

If, for some reason, your drains aren't sealing well, LASAR has a little kit of o-rings to reseal them, $7 a pop. This happened to us! But resealing the wing (pitot) drain will be a trick to get to, it is accessible from inside the cabin, you will need to remove the front seats and the cabin liners at the left wing root. Then there will be several wire bundles that need to be moved out of the way. Expect that the vampire airplane will want a blood sacrifice before further cooperation, so drip a little somewhere, and then the drain piston will come right out.

Gary, welcome! We are nearby in Seattle. My first M20 was an F, between my wife and I we have owned 4 different Mooneys. What kind of updates did you do?

Hi 7MC Welcome to the forum. Scott is right on that Gill, we have not used them in years. The Concorde 35AXC will help.....however, make sure you are charging correctly and that there is no drain on the electrical system when the master is off. Try to figure out how to get that batteryMINDer on your plane when it is parked. It is a great device, we have one on both our planes, the Aerostar really likes it since we have to start 2 turbo-Lyc 6 bangers in a row on the same small(ish) battery.

Gary, I would like to add my voice to what Byron and Scott are saying. Leave that throttle in and leave the prop at 2700. It is a hard thing to find out that nearly everything you were taught about operating CS prop equipped aviation engines was pretty much flat wrong. You may also try climbing with that power setting at 130 mph. That "seems" fast, but it is the best way to climb until you can't maintain around 500 fpm. The climb profile is called Vz, take a look in the forums you will find a lot on that.

A couple of additional items for aaronk25: it sounds like you are trying to maximize mpg (least fuel used). If you are maximizing mpg on climb, it also makes sense to fly maximum ENDURANCE speed (min fuel flow) on your cruise. At cruise, that is a very low power setting, and the specific fuel consumption is higher than it would be for a ~65% cruise. As Byron said, your LOP climb will result in a longer distance to climb. If you then do a ROP climb next, after level off you are not at the same point from takeoff. You will most likely be closer to the takeoff point. Evaluating fuel used at that point is incorrect, because you are not at the same point in the sky. You will have to cruise some to get to the top of climb point for the LOP climb you just accomplished. Again, your measure of efficiency is not rigorous unless you factor in the velocity made good into the evaluation. Speed has a value, just like fuel. The CAFE parameter I have written about extensively is, in my opinion, the most valuable measure of merit when discussing small airplane efficiency. You will need to hold every other parameter nearly constant to do a comparative performance analysis. That will include flying back to the airport after your first climb and refueling so your first and second takeoffs result in the airplane weighing the same for both. Flying the second flight 30lb lighter will invalidate your results. Same thing with weather, you need to fly the points back-to-back during a time of day in which the temperature, winds and barometer setting are pretty much the same. Once you note the time, fuel and distance to the same point using both techniques (assuming you are using about Vy (88KIAS or 86KCAS for the J), evaluate it this way: Velocity Made Good = Distance/Time. You will get some airspeed number. Raise that number to the 1.3 power. MPG = Distance/Fuel Used. Then multiply Vmg**1.3 x MPG. That number is the CAFE parameter. The higher number is more efficient. You should be able to produce a data table like the one below. Also, if you are savvy with the track log function of a GPS and Google Earth, you should be able to produce a visualization of the flights like the photos shown below. There are two flight tracks in the photos. The Vy one is in magenta, and the Vz one is in white. Vz top of climb used 4.1 gallons. Vy climb was 3.5 gallons. Is that more efficient? No. The airplane is 7.5 miles closer to takeoff. Flying down to the Vz top of climb point in cruise used .6 gallons. The fuel to the same point in the sky was the same, but the Vz climb velocity-made-good was 95 knots, the Vy was 76. 19 knots faster on the same gas....achieved solely due to pilot technique. This particular test day had a very strong headwind for the climbout path. However, since you are after comparative data, the test day conditions don't need to be normalized to standard day conditions. You may wind up with higher CAFE scores due to a tailwind, but you can only compare data obtained under nearly identical conditions. I have gotten similar results with an M20K (with STCed wastegate and intercooler) and an Encore. Also attached is the test card used to hand-record some of the data on the flight. Hope this helps. Look forward to your report! Vz Flight Card.pdf

Thanks for posting that. The chart says the configuration for Vy is 15 deg of flaps, is that what you do? Is there a climb chart published with flaps retracted?

MJC, I know you said twins may be out of the question, but I'll try again anyway. There are more than a few Mooney drivers who went to the Aerostar twin. I am one of them. The turbonormalized pressurized 601P with the "big" turbo option is not just a step up, it is a game changer. It is possible to fly this airplane at 6000' or 25000' efficiently in comfort, and philosophically the design is right in line with Al Mooney's designs. It is a 26gph airplane when flown 65% LOP, but at 25K you get 228 knots true. Lower is slower of course, but you have the choice of a huge range of altitudes to allow for favorable or adverse winds. You will probably spend about $200k to purchase one and do the catch-up maintenance needed to make it reliable. Aerostar Aircraft is still in business in Coeur D'Alene, Idaho and fully supports the type design with parts, improvements and tech support. And it flies like an absolute dream.

Trying to upload my thesis, the uploader barfs after momentarily showing the upload. Anyone wants a copy just PM me, it is a 12.7mb PDF file.

Great post Hank! A comparison of climb rates is quite a bit more complex than most people think. There are a host of factors that affect rate, and although the instantaneous climb rate at any condition is somewhat interesting, the real parameters of interest are time, fuel and distance to climb. That's why the chart is listed that way in the earlier POHs. And predicting climb rate at any other condition than Vy (required by the FAA for certification) requires a rather lengthy set of performance calculations, which cost a lot of money. Mooney did publish a "cruise climb" schedule in some of the latest POHs...there is one for the Encore and some of the Ks. I'll take a look and post a picture in a bit. Hank, what is your published Vy speed? Carson's Speed is about 1.3 times that, however, Carson's has never caught on as a cruise speed because the resulting power is just too low, unless you are at a very high altitude. And winds aloft are an overriding factor in cruise velocity-made-good, so efficient flight (max CAFE score) has as much to do with flight planning (choice of altitude) as it does with engine operation. In a nutshell, my thesis shows that Carson's Speed is a pretty ideal climb speed, subject to performance limitations (500 fpm)...which is the Vz climb profile. Jack Norris touched on this in his book "The Logic of Flight", but he did not discuss target EGT or factor in any consideration of performance limits or winds. John Eckelbar wrote about cruise climbs in his book "Flying High Performance Singles and Twins", he discusses a cruise climb of about 1.15(ish) times Vy, but does not rigorously show the efficiency (speed and mpg in proportion). 201er wrote: "Can someone lay the case and justify LOP as being more fuel efficient in the long run for climb in the span of an entire trip." Actually, you can do that yourself! An LOP climb may be more fuel efficient, but it may (will) take more time. You can't make full rated power lean of peak with these engines. So the time to climb to any target altitude will be longer. And LOP ops above around *roughly* 70% power run a higher risk of detonation unless you are significantly lean of peak on the richest cylinder. And you will quickly get to a performance limit (500 fpm or less) where it is pretty hard to keep climbing consistently. For the span of an entire trip, choice of cruise altitude to maximize your CAFE parameter for the trip is a much bigger factor than climb technique...and the tradeoff of a reduced-power LOP climb means a "little" more time down low where you don't get the advantages of higher true airspeed for a given IAS. For Byron, I have not yet modeled an LOP climb in Benchmark.....but it would be possible to do a back-to-back flight test comparison of Vz to whatever LOP climb technique one would want to evaluate. You need a handheld GPS with track recording capability and an accurate fuel totalizer. The test cards and the procedure are in the thesis, if I can attach it. You would need to change the procedure for any LOP climb (I compare the published POH Vy technique to Vz), and compare the resulting CAFE scores at top-of-climb for whichever technique resulted in the longest distance to climb.

For Byron, you should be able to get "around" 550 fpm at Vy, 9000' PA, gross weight and standard day. At 115 KIAS you would get only about 280 fpm, per Benchmark.