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Urs_Wildermuth last won the day on March 23 2018

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About Urs_Wildermuth

  • Birthday 12/27/1962

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    M20C, 1965

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  1. So after about 10 hours into the new prop, we now are working with a constant degradation of 5 kts in comparison to what the 2 blade prop was, with identical fuel flow. As most of this 10 hrs were recurrency training, we donˆt really have proper cruise data up high yet. If this confirms once we get to fly more, it would mean quite a significant loss (5 kts means an average planning speed of 135 KTAS rather than 140 we had before) but not as dramatic as 8 or 10 kts. With a 4 hour range, it would kick some 20 NM off the plannable rage and a cost increase of about 6% over a 500 NM distance. Not nice, but we will have to live with it. Take Off RPM and MP is higher now, I have no exact figures reported to me yet, but it appears the adjustments did something. Take off performance is notably better. One other bit is Weight and Balance... the new prop installation is now approx 10 kgs heavier and causes a massive CG movement to the front. I have to play with this a bit but all in all, this will further restrict range as both Weight and CG are now critical. For training flights with 2 up front and full tanks, we will need some 30 kgs of ballst in the baggage compartment to get it back into envelope.
  2. Of course not. Most people will eventually get a preferred setting they use all the time. So do we in most cases. Yet that setting has to be covered in the database in Foreflight or whatever you use to make sense. For most of our planes including the stock C model, those models are readily available, therefore people feed it into their Ipad and go. Nothing wrong with that in the least, or even with the more basic approaches, as long as people are familiar with them. The way you do this does not matter as long as they coincide. I know. Let me tell you that for example there are much worse "Range" figures in other makers POH, even though much better "organized" but just as wrong. I've been using a different algorythm for a long time to generate Range figures. And guess what, they are quite a bit smaller than POH figures. You know, I really don't want to make things more difficult or to as the saying goes in Switzerland "make a doctorate out of it". The main thing is to get some basic data to start with. The rest is easy. And the aim is to provide something which the other pilots can use for information which looks and is easy to use, such as the old tables printed on the sunscreen of most Pipers. I had all that for the C as it was and now it needs updating, that's all that is to it. I REALLY don't want to tell anyone else how to go about things, really, all this is about getting some data. I am quite happy with the results, as they confirm my gut feel: 1. we know that the take off RPM/MP is way too low and we know as well that there is at least someone who gets the figures he expects with the same prop. That means for me we need to find out if our installation is faulty or what is going on. And then we will figure out the rest.
  3. Well, Ross, you probably fly a lot more than I do. And in the US, you have countless airfields and airports where you can decide to land and fuel and where you can do so without prior permission (often up to 48 hours ahead) and similar stuff. Clearly, that makes it a lot easier. I would not dream of calling anyone names because of that! Also, with the fuel prices we have, we really aim to fly as efficient as we can. And personally I fail to see how to achieve that without proper performance data. Quite often it turns out that what people THINK is quite different from what transpires if someone who knows performance looks at it. Anyway, all I wanted to get in this thread is some information what other people who have this STC get in terms of figures.
  4. It depends what exactly you are doing but I'd say for rather short range (in airliner terms) commutes you stand a real good chance. My base route e.g. is Zurich to Salzburg. In the old days, there was a Fokker 70 route (later a Saab 2000) which took about 50 mins flying time. So with check in, check out (not counting getting to the airport as the Mooney also resides there) the airliner took the better part of 2.5 hours per way. The Mooney flies this distance in 1-20 and I usually managed to get out and started in about 20 minutes after reaching the airport, sometimes 30. So yea, it will beat the airlines but primarily also the schedule is mine, not theirs. In recent years, I had to fly to Bulgaria with dogleg flights as there were no convenient direct flights. The result was mostly trip times airport to airport of above 6 hours, which is what the Mooney takes to fly the same distance with a 45 min fuel stop. But with the Mooney, I can go to where I actually want to go, not just to the Capital city. So yea, in many regards Mooneys will be faster or at least not slower. This does change obviously when distances grow further.
  5. Well, I guess that is in my dispatcher's blood. During my airline time I came across some really challenging datasets which needed to get into computer generated flight plan or weight and balance models. I probably was one of the first who managed to get a DC3, Caravelle and a TU154M into a electronic load and balance program (in the 1980ties mind) from simple graphic data. Later we did performance evaluations for high fidelity flight sim products. And if you think I am picky about numbers, don't ever mess with that crowd So I am not simply some sort of number freak, but I like to be on the precise and safe side when doing the docs for my airplane and I want to have a pretty good off hand idea what it can do. But primarily I want a dataset I can safely put into flight planners and which actually work. No point in taking a default C performance model and wondering why it's calculating wrong. For what I use, this requires a complete 75/65/55% power table plus some other goodies which for now remain the same (time fuel distance to climb/descend). That is all. And btw: At least in Switzerland, we are strongly encouraged to have an Operational Flight Plan available in case of ramp checks. In Europe many people still carry a paper briefing package for that purpose. Myself, i also find it easier to work with. But as you say, each to his own. In order to generate an operational flight plan, data needs to have some semblance of accuracy, otherwise in the case of an incident or heaven forbid accident, the authorities will have a field day proving you negilgent in flight preparation.
  6. I think I know what you mean. Of course there is always the unexpected and it's also part of the fun.
  7. Yes, both up and downlock. I actually had the chance to operate them today on the blocks and they work superbly. I also got the cowl closure, but that one will have to wait to be fitted until later. It is more work than I tought and the shop can't accomodate it right now. It's not any where close as unobtainable than you think and once you are set up with a proper flight planner and really good and verified data in it, it's a very easy thing to do just that. I used to have some fun with a friend of mine whom I visit by plane from time to time, after departure I text him my ETA and he will turn up exactly on time to verify. So far, the only time I got in there late was due to holding at destination. And so far I've never yet had to get even close to my final reserve fuel, even though we have done 5 hour flights with the airplane.
  8. Ok, thank you, that is very good to hear. I have not been looking at rumours but at the actual numbers from our test flight, which was done with 2300 RPM as we did not get the information about the 2350 RPM limit in time. Cruise: (All DA and TAS) 75% TAS at 5000 ft between 138 kt with FF 10.6 GPH. According to the book it should be 146 kt at this FF 65% TAS at 5000 ft we got 127 kt. FF 9.2 GPH. According to the book, it should be 136 kt at this fuel flow. 75% TAS at 10'000 ft we got 140 kt. FF 10.6 GPH According to the book, it should be 153 kt. 65% TAS at 10'000 ft we got 135 kt, FF POH9.2 GPH. According to the book, it should be 141 kt. This gives a consistent 6 to 8 kt less than book speed. And while it never reached fully book speed also before, the differences were less pronounced, max 1-2 kt at 75% and pretty much spot on at 65%. We also did a test with WOT 2500 RPM at 6000 ft and got 148 kt at around 12 GPH. The airplane is equipped with a Shadin Miniflo fuel computer linked to the GNS430W. No problem there. We also have an Aspen PFD so we can read off TAS direct and a Davtron instrument which reads DA direct. That is quite comfortable for what we need to do. This morning, maintenance bench tested the RPM gauge and found it accurate. A run up at DA 2000 ft resulted in 2550 RPM and 25" HG. We are all clear that this is not enough, so we are talking to the prop shop how to proceed. I am not ignoring anything, just the opposite, I collect all the values you guys give here with huge interest. And your report of being actually 4 kt above POH speeds tells me, that something really has to be checked with my airplane. It has the power flow exhaust, which in my experience has been largely responsible for us making book values with the 2 blade prop, so now getting values which I can't explain bothers me. I spent quite some time last night to produce a preliminary power table taking into account the new situation and now we will testfly the airplane against that table at 2400 RPM and 2500 RPM to see what happens. Well, incidently, I have been flying this plane since 2009. The process I am going through right now is not new to me, other than up to today, I always had POH values to fall back on, to at least give me some base line to work from. During this time we found out quite a few snags which cost us performance or we thought it did, such as a faulty K-Factor in the Shadin which gave us a wrong fuel flow, such as an RPM gauge which overread by 50 RPM, such as a wrong conversion factor between mph and kt which got introduced into a flight planner and affected thousands of users, few ever noticed and even less noticed it's gone by now. Some even claimed they did reach the wrong KTAS figures but that is down to bragging rights I think. What I can say is that if it is flown with some sort of precision, on AP and power set according to thee book, the airplane, like most, pretty much delivers a very constant performance. For economic reasons we always flew the airplane at 65% and sometimes 55% if we had to play range vs speed and it delivered with no less precision than the A320/330 and MD11's I used to dispatch. BUT, the main thing is, garbage in, garbage out. We have great flight plan systems like Foreflight and similar, which have accurate in flight winds e.t.c. but often profiles which were done with less than desirable accuracy. Add to that, each airplane has its particular performance deviation from the book, some better, many worse. I call this a performance factor and we had those in the Airbusses and MDC's as well. Individual fleets could vary up to 1-2 %, which in a 100 ton airplane is quite a lot. I've done some adapted tables for friends who fly Mooneys and other airplanes, if you really put the work in and get flight data back, those things are not worse than today's airliners with all their FADEC's and fancy displays. You'd be surprised how many folks don't even know the real meaning of TAS vs IAS, can't work out a Fuel Flow even if it is displayed right in front of them and are simply uninterested in the nice features such as fuel computers e.t.c. we all have. Well, part of my fun I have is to be able to really plan my flights properly and to be able to fly them in such a way that pre-planning results work out in a reasonable fashion. I find that this way I can go much more towards the performance limits of this wonderful airplane than people who simply go fuelling every two to 3 hours no matter what. I recall vividly how we got a friend of mine out of a very short runway where one of his pilots had landed with a tech problem after they had thought to use a helo to get it out, but in the end the POH was right and it cleared the far end comfortably, after waiting for a day for conditions to be just right. For me, a cross country flight is successful if it arrives within a couple of minutes of EET and +- 1 USG of either fuel remaining or used on the operational flight plan. Flying in an environment where most airports are PPR and many (including my homebase) give out tight slot times of +-15 mins you have to hit or divert, you can't afford not to know your performance. Well, with enough effort, you can make an actual POH which works, has the correct stuff inside and can even be approved by the competent authority. I've pretty much done this for my plane with the performance part, (well I thought I did, back to square one now) and procedures, I might do it for the actual systems and equipment too. The stuff is out there, it just takes someone to organize it and put it into writing.
  9. How do you want to plan a flight, produce a legally acceptable Operational Flight Plan and fuel calculation if you have no idea about the speeds and consumptions? WOT at 8000 ft means some 75% power with 11 GPH. We usually cruise at 65% power with 9 GPH. At that altitude this would be somewhere around 20" and POH TAS of 140 kt. No, heavens no. We lean very agressively from the start. I am a former flight dispatcher and I get very uneasy about going into undocumented territory when it comes to flight planning. Not to mention that there are no indications about the speed loss the 3 blade prop causes vs the POH TAS. I am now hearing 8 to 10 kts, which would be horriffic. Basically turns a M20C into a PA28. Also we do operate the airplane (any airplane we operate) strictly by numbers out of the POH, not just some guesswork. The way I see it we will now start using a 10 kt performance penalty and increase final reserve to 1.5 hours on flight planning for the time being while we have to testfly the airplane to figure out what it actually will do. As nobody appears to have legit figures I don't see any other way. This about halfs the range of the airplane for the time being, but with no figures available, we basically have to start as if we had an undocumented experimental on our hands. Clearly I was totally naive and stupid when it comes to the impact of this prop change. I expected some improvement in noise fees and I really did NOT expect loosing 10 kts of speed. We will see, most probably we will have to change back to a 2 blade prop in the not too distant future.
  10. How much for the prop? Has that any chance of being made servicable again? Wonder if it will fit in a hat rack on an airliner...
  11. Thanks. That confirms what I think. That prop's governor needs some talkin' to. Well yea, but that means you can calculate or at least estimate what 65% is as it is between 63.1 and 67.3. On the 2400 table the lowest you get is 70% if I recall right. So what if I need a setting for 65 or 55% i.e. to feed a flight planner? We can't very well use our former airplane profiles otherwise that prop won't last very long, they tend to get bent when people run out of fuel 200 NM before their destination and land in a cornfield! And as our British friends point out, that is NOT Cricket.. and there are cheaper ways to make popcorn. Hey ya all, keep it cool. Yea, I am in Europe and within that in Switzerland. Avgas prices here have gone beyond the current rate of 3.26 CHF per Liter (after coming down from more). Soo, one USG last time I looked was 3.78 liters, consequently a US Gallon costs 12.32 CHF per USG. And the US Greenback is noted at 0.97 to the Swiss Franc right now, so that makes it $12.70 per USG. Today. Thankfully I only need to fuel on Friday But seriously, I think some here have gotten their boots on the wrong way about this before. European Fuel prices are a totally different league than in the US. Why do you think we fly Mooneys and why do you think Tesla is selling way too many cars over here. I fuelled normal 95 grade autofuel two days ago for $9.13 per Gallon. Before Uncle Vlado threw his wobbly prices were somewhere in the 1.70 CHF for automotive fuel and 2.30 for Avgas, so if you do your math right, that would be between 6 and 9 $ per USG respectively. We are used to it, mortage our houses and carry on flying. Oh, yea, and I got a 1300 USG heating oil tank buried under my back garden which I need to fill. I just hope the oil speculation will go back to pre-Ukraine levels before I have to do that. Otherwise, another mortage... They all but had to revive me some years back when I filled up my rental car in Miami after 2 weeks of driving on one fuel tank. Swiss and Europeans tend to have nervous breakdowns and google searches for Greencard Lotteries at gas stations in the US. Chill. It's normal. Enjoy it while you can. Anyway, there is one good thing about this bickering about European prices here... I can do the math between liters, gallons and between CHF and USD in my sleep now.
  12. @Hank and whoever else flies with this prop: What static and what rolling take off power do you see at Max Take Off Thrust? At the test flight we got 25" and 2500 RPM with all the levers full forward. OAT was about 27 degrees Centigrade at 1400 ft, so about 2000 ft DA.
  13. @Hank, My problem is, the POH does not even give figures for 65% at 2500 and 5000 ft for 2400 RPM. So how can I e.g put a proper planning together at 65% in those altitudes. If I read the performance part of the manual and look for 65% at 2500 or 5000 ft there is simply nothing there. The long range cruise figures we had with the 2-blade prop were based on 2300 RPM and optimized figures out of the tables, basically see where you get the largest range with least consumption and within a reasonable time. The 1800RPM cruise does not make sense unless you are up for an endurance record, as the time you fly (and with it get to time limits TBO, 50 and 100 hour checks faster) also is part of the aim to fly efficient. From what I've seen so far, 2400 RPM in the lower range figures ups the consumption, therefore decreasing range. But all of the stuff in the POH is with the 2 blade prop. So what about the 3 Blade ones? I have no table which even tells me it has no influence on the POH figures (apart from the restriction) so in fact, I have no document available to tell me the performance of this airplane. So what do I feed into the 65 and 55% sections in the flight planning computer? On what basis do I do my fuel calculation? Which to me means, we have to go out there and figure them out with test flying. With Fuel prices up to 12 $ per gallon and rising, simply putting the pedal to the metal does not work anymore, at least not for me. We always flew 65% below 1 hour of flight and LRC whenever above it. Only that with 2400 RPM, the figures aren't even there to start calculating.
  14. The STC gives two restrictions: Avoid continuous operatio below 15 inches HG between 1950 and 2350 RPM. If Powerflow STC ... for a tuned exhaust is installed: Avoid continuous operation below 22 inches HG between 1950 to 2350 RPM. The latter imho is a total killer, as it means no more long range cruise and loss of most of the performance information we have in the POH! If we have to fly 2400 RPM all the time, 65% power is not possible below 7500 ft using the POH, let alone 55% or any other power setting. That means pretty much no long range cruise, worse range and so on. There is also no information in the STC the way I see it as to what performance factor the new prop has. So basically we have to testfly this? I am extremely angry at myself (and the others involved in the purchasing of this prop) for not seeing all this before I ordered, i would never have ordered this prop with these restrictions. But now we have spent 20k$ for the darn thing, we don't have money to throw it out and buy another. And without validated performance tables, how are we supposed to operate this airplane? The thing I see coming is that we have to testfly it in all configurations in order to find out what FF and TAS we get and basically recreate the performance section. Before that, we can't release the plane to the other pilots who fly it as well. I honestly wonder how this STC could have been approved without all this vital data. So I still am asking the same question: Those who fly this prop with or without the Powerflow exhaust, what performance tables do you use? Standard POH are obviously for the 2 blade. So we are basically on experimental ground, but with a certified airplane.
  15. We just got this prop installed. Due to the power flow exhaust we also have, we find that we are massively restricted in power settings, as there is a note to avoid continous operation between 1900 and 2350 RPM with MP smaller than 22". Question: Does anyone have performance tables for this configuration? I just looked at the M20C POH and it is e.g. not even possible to determine a 65% cruise regime if you are limited to run the prop above 2350 RPM. Likewise, there are no data on fuel flow or similar things. How do those who run this prop on the M20C calculate their performance? Just by experience? Or is there some documentation for this?
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