sandpiper Posted July 7, 2011 Report Share Posted July 7, 2011 A power reduction at 500' AGL is just fine. This is normal practice in many Cont & Lyc engines with CS props. In the fixed pitch rotax set properly there is no real reason to do this unless temps are a problem which shouldn't be the case after only 500' of climb. But, I can't think of any good reason in normal circumstances to come back to 3950. No, you shouldn't be cruising at 4000 RPM. Listen less to what you hear at hangar flying sessions and more to what competent instructors and the manual tell you. Four years ago my plane came from FD set to 5300 rpm flat out. I changed to to 5450 and was happy until just recently when i changed it to 5550-5600 flat out which now gives 5150 in climb. I'm happier with that. Seems cooler, too. Today I went from 180 msl to 6000 msl and topped out at 235 degrees oil temp. The sooner you convince your planes keepers to do this, the happier all of you will be. Link to comment Share on other sites More sharing options...
mocfly Posted July 7, 2011 Report Share Posted July 7, 2011 Roger, When speaking to an LSA Rotax mechanic about the whole pitch issue his comments were that he "advised caution and "if the plane isn't in the experimental category he can only put it back the way the manufacturer wants it" What the ? Sandpiper, Which manual are you referring to? FD? Rotax? There I a discrepancy here. Link to comment Share on other sites More sharing options...
mocfly Posted July 7, 2011 Report Share Posted July 7, 2011 Roger. Could you ask the gentlemen from fla if he is going thru Chattanooga on his way back and or if he would be available to speak to me directly after the work is done and he has been on his way for a few legs? Thanks Link to comment Share on other sites More sharing options...
opticsguy Posted July 7, 2011 Report Share Posted July 7, 2011 I have my CT pitched on the coarse side, though I did back it off 1 degree from the factory. I think it will do 5400 WOT at 2000' MSL. I throttle back to 28 psi a few hundred feet off the ground for climb. The hottest my oil has gotten, after a 30 minute climb to 6500 ft (where it was still 25C) was 205F. I cruise at 5150 RPM, a good combination of speed and fuel burn. Some CT's cool better than others. Mine cools so well that I need to tape the radiator below 60F (600 ft MSL) Link to comment Share on other sites More sharing options...
sandpiper Posted July 7, 2011 Report Share Posted July 7, 2011 mocfly, I was thinking generically but normally I would go by the manufacturers Pilot Operating Handbook (POH). Link to comment Share on other sites More sharing options...
sandpiper Posted July 7, 2011 Report Share Posted July 7, 2011 Roger says 30 minutes to repitch as in from taking the cowl off to cowl back on and ready for flight. And he can do that. I know 'cause I owe him a dinner on that one. I, on the other hand, take a little longer as I don't do it very often since I generally only work on my own plane. So, having only done this 2 times (three if you count the favor I did for a friend) it takes me a little longer especially if you add in repeat trips to the tool chest to finally end up with the right tools, extra time reading the manual, etc. Still, it's a quick and easy task. Link to comment Share on other sites More sharing options...
mocfly Posted July 7, 2011 Report Share Posted July 7, 2011 Sandpiper, I would agree except in cases like this where engine manufacturer and aircraft manufacturer are not in sync, as Roger has pointed out on numerous occasions within this domain. Link to comment Share on other sites More sharing options...
sandpiper Posted July 7, 2011 Report Share Posted July 7, 2011 That's why I used words like "generically" and "normally". In this case I tend to come down on the side of rotax which is apparently what FD does with its new planes. I mean, mine was delivered with a full throttle climb of less than 4800 rpm. That's just too low. You could feel and hear the engine struggling if you were even remotely mechanically inclined. After that rotax came out with new instructions and FD has followed that new guidance. Link to comment Share on other sites More sharing options...
mocfly Posted July 7, 2011 Report Share Posted July 7, 2011 No one in my club has ever said it feels laborious in climb. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 7, 2011 Report Share Posted July 7, 2011 Hi Mocfly, I don't think your plane's engine is necessarily laborious, (I know what sandpiper means though) but I don't think the people in the club would know the difference if they haven't flown all different prop settings on that plane not to mention the different props. I'm not dissing your friends it just they don't have all the years and time with Rotax engine setups. I have flown 3 different props (getting ready to fly a fourth) and at least 40 different CTSW's and LS's (other 912 aircraft too) at all different settings. I'm very comfortable giving advice on CT prop settings as they reference performance. I'm on several other forums and give the same advise to those 912 owners. Many people don't know how a Rotax should run properly because they haven't flown enough Rotax engined aircraft or CT's for that matter. I know who you are talking to Florida and to that end, he/they have a little different philosophy than some. I will tell you that FD wants the rpm set to 5500 WOT rpm and Rotax to at least a minimum or 5500 WOT, but they don't specify at what altitude. This is for you to set up for your specific location in the world. You need to decide if you are using a ground adjustable prop or a constant speed and specific flight characteristics (i.e. density altitude). This will determine other parameters for you to follow. FD also says to follow the Rotax manuals and all SB's. Both sets of these documents talk about not running in the low rpm range at WOT or during cruise and that if it gets too low can cause damage to the engine. No, you are not in the damage range, but you are definitely too low and you're just in the poor performance range for your normal density altitude. I have reset the WOT rpm on several different SLSA's with Rotax 912's and not a single person has gone back and everyone says it feels like their plane got a boost. Someone would need to show me in writing where FD says you can only set the prop exactly where it was when delivered? There isn't anything and it isn't restricted in any FD manual. FD says to follow the Rotax manual and that gives you the leeway to make adjustments to help and protect your engine.. Here is the best solution. Believe none of us and have the flight school mechanic or you go take the Rotax school. That will answer all your questions right from the horses mouth so to speak. Call around to a few other Service centers (i.e. CPS, a Rotax distributor and ask for Jeremy) and see what he says. I don't think this gentleman is coming back through Tenn. Link to comment Share on other sites More sharing options...
sandpiper Posted July 7, 2011 Report Share Posted July 7, 2011 I'm just saying that to my precision M1A1 ears, which CHS, the engine sounds alot "happier" now than it did when I got it. Link to comment Share on other sites More sharing options...
mocfly Posted July 7, 2011 Report Share Posted July 7, 2011 Roger, I agree with what you are saying regarding the members in our club. I know that this is the first Rotax powered machine that I have ever been in, so I defer to people with your level of experience when it comes to questions such as this. I'm gonna put all the cards put on the table for the executive committe of the club and let them make the call. Its certainly going to make it harder to fly it to Oshlosh knowing what I know now, if the call is not to get the prop done. And you can bet that I will be a visitor to both fd and Rotax to get some definitive answers, cause it seems they can't get together. Maybe a public question during one of the public forums they hold during the show? It is a great little plane and I really think it will be a good acquisition for the club. However issues like this make people reluctant to fly it. Again, Thanks Roger If I get out to Tucson I'll be sure to look you up. Another quick note. So you have CPS number? And did you see the reply from fd about the use of TCP? Link to comment Share on other sites More sharing options...
Roger Lee Posted July 7, 2011 Report Share Posted July 7, 2011 CPS is 510-357-2403. You may not get some people to come together on a specific answer because some just have personal biases. Your flight to Osh will be just fine. Your numbers just aren't that far off. At Osh go find the Rotax tent/display and ask Eric Tucker what he thinks. Eric teaches and has taught all these people in the US for Rotax. Instead of using TCP with the harsh chemicals that isn't supposed to be in the cabin, try Decalin that does the same lead scavenging without the harsh chemicals and it's far easier on the aircraft fuel system.. Link to comment Share on other sites More sharing options...
mocfly Posted July 7, 2011 Report Share Posted July 7, 2011 Roger, Have you worked with anyone close to me that has your iunderstanding of what we are encountering? I'm trying to get an idea of cost for the re-pitch. In order to make a case to the club membership to re-pitch I need to know a cost along with what type of performance increase we would expect to see. I can call a recommended tech for cost and would ask for opinions or observations of what others have seen. This all may be mute but I owe it to the guys in the club to put all the applicable information in front of them. Again thanks for the input. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 8, 2011 Report Share Posted July 8, 2011 Mocfly, The charge should be about $40-$50. It will take someone 35-50 min. You will get better climb, better cruise speed, better fuel economy, better oil temps, better CHT's and you'll feel better that you did it and feel better that now you know more than the other guys who did it. To me it looks better all around. I just did that gentleman's from FL. today. and he is faster, climbs quicker, off the runway quicker, less fuel use and faster in cruise. What's not to like. (There sure are a lot of better's in here, I hope I'm right! ) Link to comment Share on other sites More sharing options...
mocfly Posted July 8, 2011 Report Share Posted July 8, 2011 Roger, If it were mine alone it would have already been done. It's gonna be a hard argument when the reseller doesn't concur and continue la to rake the stand that what we are seeing is normal. Im gonna hook up with a friend who is flying a 172 to osh, and he plans on talking to the guys at fd about purchasing one. The performance while we travel together will either work to make his choice easy or if as I suspect the performance I gonna be marginal, will cause him to ask some pretty good questions. It will be interesting to watch that dialogue. Especially since my plan is to take engine instrument readings every 1/2 hour on the way up to put in a spreadsheet. Stay tuned. I now trying to find a comfy seat cushion. Link to comment Share on other sites More sharing options...
mocfly Posted July 8, 2011 Report Share Posted July 8, 2011 Please excuse the typos. My fingers are to fat for the iPhone keyboard Link to comment Share on other sites More sharing options...
Roger Lee Posted July 8, 2011 Report Share Posted July 8, 2011 Many people will have an opinion on this subject, even the experts. But ask how many different CT's they have flow, how many hours total time in a CT, different props flown and different rpm settings to compare on each. That should weed out a few. Link to comment Share on other sites More sharing options...
mocfly Posted July 8, 2011 Report Share Posted July 8, 2011 And of course there will be a few ct guys at the show that I'm gonna seek out. Link to comment Share on other sites More sharing options...
mocfly Posted July 8, 2011 Report Share Posted July 8, 2011 Another interesting tidbit is that when i was inspecting the engine logbooks today after changing the oil the rpm setting was 4950 from the factory. I couldn't find another place where the rpm was again noted. What the? Link to comment Share on other sites More sharing options...
Tom Baker Posted July 8, 2011 Report Share Posted July 8, 2011 Mocfly, I am about 300 mile from you in southern Illinois. I would be glad to adjust the pitch on your prop for you. Like roger said less than $50 should do it if nothing else is needed. My first CT had the prop set just like yours and I had oil temp problems. The airplane was sold before re-pitching the prop idea started going around. I did repitch the prop on my current CT and have seen all the advantages that Roger spoke of. I have also started doing it for my customers as their airplanes come through for maintenance, with their permission. All have liked the differences in the numbers they have seen. Tom Link to comment Share on other sites More sharing options...
mocfly Posted July 9, 2011 Report Share Posted July 9, 2011 Tom, Can I get your contact info? You can send it to my email. Chrismarinello@yahoo.com You wouldn't be planning on going to Osh would you ? Link to comment Share on other sites More sharing options...
mocfly Posted July 10, 2011 Report Share Posted July 10, 2011 Guys, If the Rotax manual sets wot@5200 0msl what would the measured manifold setting be at 3500 da? Of course they want to measure it using a manifold gauge. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 10, 2011 Report Share Posted July 10, 2011 Hi Mocfly, Manifold pressure for us using the ground adjustable prop and naturally aspirated engine isn't a great help since we can't do anything about it in flight. Now if we had the 914 Turbo and a constant speed prop then that would be needed and helpful. Link to comment Share on other sites More sharing options...
207WF Posted July 13, 2011 Report Share Posted July 13, 2011 The old rule of thumb is you lose one inch of mp for each 1,000 feet. WF Link to comment Share on other sites More sharing options...
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