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Another RV-10 flying! (with some performance questions)

 
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dan(at)syz.com
Guest





PostPosted: Sun Jan 29, 2017 1:35 am    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

Hi everyone.

I'm happy to say that after 11+ years of work, my RV-10 is finally in the air. As a testament to Van's incredible design (both in terms of the airframe performance and reliability, and perhaps equally importantly, in producing a kit that newcomers to the idea of homebuilding can build safely) , the first flight (and subsequent ones) have been pretty much uneventful. Everything "just works" - the plane handles like a dream and I'm looking forward to spending thousands of hours flying it. Still a ways to go yet - I'm currently at 9 hours of flight time in it Smile

But as nice as the plane seems to be, I'm in the phase right now of analyzing the heck out of everything to make sure it's operating as it should (fortunately, I have some AFS EFISes in there that log data for me to go over afterwards). And though the plane is operating 99% as well as I hoped for, there are a couple of things not operating quite as I expected - I'm after other people's advice to see if they've experienced something similar. Any help or insight anyone can give on any of these issues would be greatly appreciated!

My plane is a pretty standard build with a factory-new Lycoming IO-540 D4A5 and 3-bladed MT prop.

1. Fuel pressure drop climbing to higher altitudes: Today, I did an "informal" climb at 110 KIAS and 2500 RPM/full throttle/full rich to 10000' to see how it would handle it. At around 3200' MSL, I see a fuel pressure of about 21psi with the engine pump (boost pump off). But in the climb, the fuel pressure drops significantly. At 5000', it's at 18psi, at 7000' it was about 16psi, then it started dropping faster. At 8000' it was down to 13psi and by 8700' had dropped down to 11psi. I turned the boost pump back on and it promptly shot back up to 20psi, so I continued the climb to 10000' and then made my way back down. By the time I got back down to 4300' I turned the boost pump off and the engine pump maintained pressure at 22psi. I never did take the chance to level out and test pressure further - without knowing if it was a significant cause for concern, I got back down to the lower altitudes instead. I haven't seen any significant pressure fluctuations in flying around under 5000'.

According to the Lycoming manual, the fuel pressure for the IO-540-D4A5 at the fuel injector is supposed to be between 14 and 45 psi. This is where the Van's stock fuel pressure sensor is measuring, isn't it? Though I've seen at least two other pilot's RV-10 POHs that use numbers for the acceptable pressure to be what Lycoming quotes as that for the inlet to the fuel pump of -2 to 35 psi, so it's got me wondering if I'm misinterpreting either the Lycoming documentation or the fuel plumbing. So the question I have - is that low fuel pressure the cause for concern I think it is? If so, what might be causing it, and how would I fix it? Or is it normal? What do other people see in climb to 10000'? Though I can use the boost pump for climbs to higher altitudes (and I've heard of some certified aircraft that suggest it), it doesn't strike me as an appropriate measure if the boost pump were to fail.

2. Rate of climb at high altitudes: I haven't constructed the wheel pants yet, so I know performance will improve when they're done. At low altitudes I certainly can't complain about rate of climb - with 450 pounds of fuel and me, I did a short field takeoff today climbing out at about 85 knots and saw a 2150 fpm climb rate. But when I got up near the 10000' point, at 110 KIAS, I was only getting around 500 fpm. I haven't done proper climb charts yet, but since I've heard of lots of people cruising in the RV-10 at 15000'-17000', how are they getting up there? My climb was at full rich, as I've been taught to do in lower performing planes - is it standard practice to lean out the mixture in climbs up at that altitude for more power? Or perhaps a slower climb speed/steeper angle than my 110 KIAS?

3. Performance in general: I did some airspeed indicator calibrations today at different power settings at 3200', and ended up with the following true airspeeds: 25"/2500RPM: 150 knots, 24"/2400 RPM: 147 knots, 23"/2300 RPM: 141 knots, 21"/2300 RPM: 134 knots, 18"/2300 RPM: 118 knots, 16"/2200 RPM: 103 knots. These numbers are without wheel pants, but with that in mind, do they seem reasonable? Vans' web site suggests cruise at 171 knots at 75% power at 8000'. I know that claims should be taken with a grain of salt, and I didn't run these tests at 8000', but if my calculations are correct, at 25"/2500 RPM I should have been producing about 80% power. Is it expected that the wheel pants and/or a higher altitude are going to make a significant enough improvement to get closer to Van's numbers?

4. CHT temps: To break in the engine, I've been running it pretty hard - usually around 25"/2500 most of the time (with some cycling to 25"/2600 or down to 24"/2400 to avoid building a ridge in the cylinder). In cruise with those power settings, my cylinders 3 and 4 run comparatively cool at around 375F. Cylinders 2, 5, and 6 are about 410F, but cylinder 1 is a bit of an anomaly. Usually it's the hottest of all, getting up to around 440 (5 degrees hotter than Lycoming's recommendation for maximum service life), though there have been a few times where it's dropped rather abruptly by 50-60 degrees (for no apparent reason I can see), making it surprisingly suddenly the coolest cylinder. But it doesn't stay there - after awhile, it climbs back up to step in line with what cylinders 2, 5, and 6 are doing... but usually stays 20-30 degrees hotter than the rest. Outside temperatures have been around 30-40 Fahrenheit during the flights so far.

Of course, at lower power settings, the CHTs all drop down to well under 400. And all power settings, the engine operation has been very smooth - no roughness at all.

I can reduce the height of the dam in front of cylinder 1, and I've heard of lots of people having to do that. But especially with the strange temperature fluctuations I'm still not sure if it's fully broken in yet, so I've been holding off until things settle. Has anyone else noticed a hot cylinder 1, and if so, how much of the front dam did you remove to cool it down? The good thing is my centre two cylinders seem plenty cool so I should be able to sacrifice some of their airflow to get #1 down.

5. Break in: I've flown the engine pretty hard now for 9 hours, but haven't seen any dramatic sign of CHTs reducing as is supposed to happen with a break in (with that said, the engine was run in at Lycoming for about an hour, and about 45 minutes on the ground under supervision of an aircraft engine shop for further break in before first flight). Other indications like "until the oil consumption has stabilized" haven't helped either - I put in about 3/4 quart of oil at about the 6 hour mark, but that's been it.... so far, it hasn't used excessive oil, and as I've only added oil once, I'm unsure of how to even define "stabilized". Now that I'm at the 9 hour mark for flight (11 hours on the engine overall), should I conclude that the engine is probably broken in about as good as it's going to get, or should I still be holding out for a noticeable drop in CHTs?

Sorry for the long email! But if anyone has any suggestions, advice, or comments on any of these or other issues, I'd certainly appreciate hearing from you!

I'm looking forward to meeting with some of you at fly ins, as soon as I finish flying off the 25 hours I need to do first!

Dan
---
Dan Charrois
President, Syzygy Research & Technology
Phone: 780-961-2213


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jesse(at)saintaviation.co
Guest





PostPosted: Sun Jan 29, 2017 5:08 am    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

1. A lot of the RV-10's do this. I know people who have changed out their engine driven pumps thinking they were going bad and nothing changed. The main thing to monitor is if your engine starts leaning out or stumbling because of it. If everything is smooth, then it's not a problem. The pressure at the inlet to the pump has a much different range because it can be sucking the fuel from a substantially lower point (the "-2") or it can be pressurized by the boost pump (the "35"). If stock, you are measuring at the pump outlet. Keep your eyes on it and you should be fine, but it doesn't hurt to run the boost pump for peace of mind.

2. You should absolutely lean out the mixture as you climb. I start leaning by 1,500' usually. I lean the EGT's out to about 100-150 degrees ROP in the climb. You can find this number by seeing what your EGT's peak at. To do this, run 20" and 2400 rpm at 3,000' and lean until they peak. I see most peak at 1,425-1,450. If so, I climb with the hottest cylinder at 1,300-1,325, and keep leaning as I climb to keep it there. I run a little more rich if I need to for CHT's, but I never run WOT much above the pattern. This will make a huge difference in your power, especially as you approach 10,000'. I suspect that 1 and 2 are somewhat related. If you start to lean, your fuel flow will decrease as you climb, and your fuel pump will be able to maintain a higher pressure.

3. Some planes are faster than others and some are slower, but I have only seen a total speed fluctuation of less than 10 ktas. The MT prop is slightly slower than the Van's-used Hartzell. Some say it's the same, and others say it's 8 knots slower. It's somewhere in that range. The takeoff and climb is supposed to be better, which I suspect will prove true once you start leaning. The wheel pants and gear leg fairings, in my experience, add about 17 kts. That should get you fairly close to the Van's numbers. I suspect you will I prove speed by leaning. Run the speed tests at 6,000-8,000 density altitude. In my experience the absolute fastest is at about 6,500 density altitude, wide open throttle, matching prop rpm and about 15-16 gph fuel flow. Most RV-10's will get 174-183 ktas in this test.

4. I suspect you have the air dam in front of Cylinders 1 and 2. Remove the dam from Cylinder 1 to see if that helps. I usually end up leaving those air dams out completely on both 1 and 2. I suspect it will. Then, increase your climb airspeed to lower those temps. Temps will come down as the engine breaks in, but those number are hotter than I like to see. Try to keep them below 400 if possible, and certainly below 420. The fluctuation seems to me to be more of a gauge issue than the cylinder. I assume these temps are all in climb. Take another look through your baffles and seal any spots where air can get to the lower cowl without going through the cylinder fins. These engines usually require at least half a caulk tube of RTV to seal well.

5. You may still get a decent drop in CHT's, but you may already be broken in most of the way. How high are you keeping your oil? I usually add 8 quarts at a change including the filter, and add a quart when it gets to 6.5. I've seen these engines settle in at 5 hrs/quart to 20+ hrs/quart. It sounds like you are at about 8-10 now. See if that drops.

Jesse Saint
Saint Aviation, Inc.
352-427-0285
jesse(at)saintaviation.com

Sent from my iPad

Quote:
On Jan 29, 2017, at 4:34 AM, Dan Charrois <dan(at)syz.com> wrote:



Hi everyone.

I'm happy to say that after 11+ years of work, my RV-10 is finally in the air. As a testament to Van's incredible design (both in terms of the airframe performance and reliability, and perhaps equally importantly, in producing a kit that newcomers to the idea of homebuilding can build safely) , the first flight (and subsequent ones) have been pretty much uneventful. Everything "just works" - the plane handles like a dream and I'm looking forward to spending thousands of hours flying it. Still a ways to go yet - I'm currently at 9 hours of flight time in it Smile

But as nice as the plane seems to be, I'm in the phase right now of analyzing the heck out of everything to make sure it's operating as it should (fortunately, I have some AFS EFISes in there that log data for me to go over afterwards). And though the plane is operating 99% as well as I hoped for, there are a couple of things not operating quite as I expected - I'm after other people's advice to see if they've experienced something similar. Any help or insight anyone can give on any of these issues would be greatly appreciated!

My plane is a pretty standard build with a factory-new Lycoming IO-540 D4A5 and 3-bladed MT prop.



1. Fuel pressure drop climbing to higher altitudes: Today, I did an "informal" climb at 110 KIAS and 2500 RPM/full throttle/full rich to 10000' to see how it would handle it. At around 3200' MSL, I see a fuel pressure of about 21psi with the engine pump (boost pump off). But in the climb, the fuel pressure drops significantly. At 5000', it's at 18psi, at 7000' it was about 16psi, then it started dropping faster. At 8000' it was down to 13psi and by 8700' had dropped down to 11psi. I turned the boost pump back on and it promptly shot back up to 20psi, so I continued the climb to 10000' and then made my way back down. By the time I got back down to 4300' I turned the boost pump off and the engine pump maintained pressure at 22psi. I never did take the chance to level out and test pressure further - without knowing if it was a significant cause for concern, I got back down to the lower altitudes instead. I haven't seen any significant pressure fluctuations in flying a!
round under 5000'.

According to the Lycoming manual, the fuel pressure for the IO-540-D4A5 at the fuel injector is supposed to be between 14 and 45 psi. This is where the Van's stock fuel pressure sensor is measuring, isn't it? Though I've seen at least two other pilot's RV-10 POHs that use numbers for the acceptable pressure to be what Lycoming quotes as that for the inlet to the fuel pump of -2 to 35 psi, so it's got me wondering if I'm misinterpreting either the Lycoming documentation or the fuel plumbing. So the question I have - is that low fuel pressure the cause for concern I think it is? If so, what might be causing it, and how would I fix it? Or is it normal? What do other people see in climb to 10000'? Though I can use the boost pump for climbs to higher altitudes (and I've heard of some certified aircraft that suggest it), it doesn't strike me as an appropriate measure if the boost pump were to fail.



2. Rate of climb at high altitudes: I haven't constructed the wheel pants yet, so I know performance will improve when they're done. At low altitudes I certainly can't complain about rate of climb - with 450 pounds of fuel and me, I did a short field takeoff today climbing out at about 85 knots and saw a 2150 fpm climb rate. But when I got up near the 10000' point, at 110 KIAS, I was only getting around 500 fpm. I haven't done proper climb charts yet, but since I've heard of lots of people cruising in the RV-10 at 15000'-17000', how are they getting up there? My climb was at full rich, as I've been taught to do in lower performing planes - is it standard practice to lean out the mixture in climbs up at that altitude for more power? Or perhaps a slower climb speed/steeper angle than my 110 KIAS?



3. Performance in general: I did some airspeed indicator calibrations today at different power settings at 3200', and ended up with the following true airspeeds: 25"/2500RPM: 150 knots, 24"/2400 RPM: 147 knots, 23"/2300 RPM: 141 knots, 21"/2300 RPM: 134 knots, 18"/2300 RPM: 118 knots, 16"/2200 RPM: 103 knots. These numbers are without wheel pants, but with that in mind, do they seem reasonable? Vans' web site suggests cruise at 171 knots at 75% power at 8000'. I know that claims should be taken with a grain of salt, and I didn't run these tests at 8000', but if my calculations are correct, at 25"/2500 RPM I should have been producing about 80% power. Is it expected that the wheel pants and/or a higher altitude are going to make a significant enough improvement to get closer to Van's numbers?



4. CHT temps: To break in the engine, I've been running it pretty hard - usually around 25"/2500 most of the time (with some cycling to 25"/2600 or down to 24"/2400 to avoid building a ridge in the cylinder). In cruise with those power settings, my cylinders 3 and 4 run comparatively cool at around 375F. Cylinders 2, 5, and 6 are about 410F, but cylinder 1 is a bit of an anomaly. Usually it's the hottest of all, getting up to around 440 (5 degrees hotter than Lycoming's recommendation for maximum service life), though there have been a few times where it's dropped rather abruptly by 50-60 degrees (for no apparent reason I can see), making it surprisingly suddenly the coolest cylinder. But it doesn't stay there - after awhile, it climbs back up to step in line with what cylinders 2, 5, and 6 are doing... but usually stays 20-30 degrees hotter than the rest. Outside temperatures have been around 30-40 Fahrenheit during the flights so far.

Of course, at lower power settings, the CHTs all drop down to well under 400. And all power settings, the engine operation has been very smooth - no roughness at all.

I can reduce the height of the dam in front of cylinder 1, and I've heard of lots of people having to do that. But especially with the strange temperature fluctuations I'm still not sure if it's fully broken in yet, so I've been holding off until things settle. Has anyone else noticed a hot cylinder 1, and if so, how much of the front dam did you remove to cool it down? The good thing is my centre two cylinders seem plenty cool so I should be able to sacrifice some of their airflow to get #1 down.



5. Break in: I've flown the engine pretty hard now for 9 hours, but haven't seen any dramatic sign of CHTs reducing as is supposed to happen with a break in (with that said, the engine was run in at Lycoming for about an hour, and about 45 minutes on the ground under supervision of an aircraft engine shop for further break in before first flight). Other indications like "until the oil consumption has stabilized" haven't helped either - I put in about 3/4 quart of oil at about the 6 hour mark, but that's been it.... so far, it hasn't used excessive oil, and as I've only added oil once, I'm unsure of how to even define "stabilized". Now that I'm at the 9 hour mark for flight (11 hours on the engine overall), should I conclude that the engine is probably broken in about as good as it's going to get, or should I still be holding out for a noticeable drop in CHTs?



Sorry for the long email! But if anyone has any suggestions, advice, or comments on any of these or other issues, I'd certainly appreciate hearing from you!

I'm looking forward to meeting with some of you at fly ins, as soon as I finish flying off the 25 hours I need to do first!

Dan
---
Dan Charrois
President, Syzygy Research & Technology
Phone: 780-961-2213







- The Matronics RV10-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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Tim Olson



Joined: 25 Jan 2007
Posts: 2702

PostPosted: Sun Jan 29, 2017 6:01 am    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

Dan,
A big congrats. I'd write a long reply but Jesse replied most of what I would have said, so take his advice. On the fuel pressure issue don't sweat it just use the boost pump. I did buy a fuel pump cooling shroud but haven't installed it. I suspect that if I did install it , it would help then fuel pressure at altitude.

Also, i did a write up late my ago about cutting CHTs. Read that and just basically check your baffling, cooling find, and seal any leaks around your cylinders. Some people place a washer spacer behind the back cylinders as well. I would halt your climb if you get over 410 degrees or even 400. Certainly don't let it hit 440 like you mentioned. Don't let the oil temp get past 240 either....or I would prefer 225-230. Keeping the oil temp under 200-210 and CHTs below 400 will be beneficial to long engine life. Climb at higher airspeeds.

Lean for climb. My person rule of thumb is to start leaning at around 5000' and lean anytime your EGTs are below 1225. Just lean them until the hottest EGTs are about 1225-1250, and keep them there on the way up.

Performance wise it's not even worth doing the numbers to compare to others until you have the wheel and leg fairings done. It's an extreme difference.

For the air dams, if you are flying with them full height just chop them down to about half. Many people remove them but I'd say start with 1/2. I don't think most anyone will have things be as cool
As they want if they leave them full height. The Rv14 Van's did smarter and they are easily removable or replaceable.

Also for climb rate, leaning will help but once you get over about 12-13,000' you're going to see that climb rate get slower. It is impractical for most people to fly the RV10 over 16,000-17,000' unless they are carrying no load. I have been full gross to 16,500 but it climbs so slowly that it's not worth it. Plan your trips to stay below 14,500 and you will be fine with the occasional excursion over 16,000.

Enjoy the plane and treat it right and it will return the favor.
Tim

Quote:
On Jan 29, 2017, at 3:34 AM, Dan Charrois <dan(at)syz.com> wrote:



Hi everyone.

I'm happy to say that after 11+ years of work, my RV-10 is finally in the air. As a testament to Van's incredible design (both in terms of the airframe performance and reliability, and perhaps equally importantly, in producing a kit that newcomers to the idea of homebuilding can build safely) , the first flight (and subsequent ones) have been pretty much uneventful. Everything "just works" - the plane handles like a dream and I'm looking forward to spending thousands of hours flying it. Still a ways to go yet - I'm currently at 9 hours of flight time in it Smile

But as nice as the plane seems to be, I'm in the phase right now of analyzing the heck out of everything to make sure it's operating as it should (fortunately, I have some AFS EFISes in there that log data for me to go over afterwards). And though the plane is operating 99% as well as I hoped for, there are a couple of things not operating quite as I expected - I'm after other people's advice to see if they've experienced something similar. Any help or insight anyone can give on any of these issues would be greatly appreciated!

My plane is a pretty standard build with a factory-new Lycoming IO-540 D4A5 and 3-bladed MT prop.



1. Fuel pressure drop climbing to higher altitudes: Today, I did an "informal" climb at 110 KIAS and 2500 RPM/full throttle/full rich to 10000' to see how it would handle it. At around 3200' MSL, I see a fuel pressure of about 21psi with the engine pump (boost pump off). But in the climb, the fuel pressure drops significantly. At 5000', it's at 18psi, at 7000' it was about 16psi, then it started dropping faster. At 8000' it was down to 13psi and by 8700' had dropped down to 11psi. I turned the boost pump back on and it promptly shot back up to 20psi, so I continued the climb to 10000' and then made my way back down. By the time I got back down to 4300' I turned the boost pump off and the engine pump maintained pressure at 22psi. I never did take the chance to level out and test pressure further - without knowing if it was a significant cause for concern, I got back down to the lower altitudes instead. I haven't seen any significant pressure fluctuations in flying a!
round under 5000'.

According to the Lycoming manual, the fuel pressure for the IO-540-D4A5 at the fuel injector is supposed to be between 14 and 45 psi. This is where the Van's stock fuel pressure sensor is measuring, isn't it? Though I've seen at least two other pilot's RV-10 POHs that use numbers for the acceptable pressure to be what Lycoming quotes as that for the inlet to the fuel pump of -2 to 35 psi, so it's got me wondering if I'm misinterpreting either the Lycoming documentation or the fuel plumbing. So the question I have - is that low fuel pressure the cause for concern I think it is? If so, what might be causing it, and how would I fix it? Or is it normal? What do other people see in climb to 10000'? Though I can use the boost pump for climbs to higher altitudes (and I've heard of some certified aircraft that suggest it), it doesn't strike me as an appropriate measure if the boost pump were to fail.



2. Rate of climb at high altitudes: I haven't constructed the wheel pants yet, so I know performance will improve when they're done. At low altitudes I certainly can't complain about rate of climb - with 450 pounds of fuel and me, I did a short field takeoff today climbing out at about 85 knots and saw a 2150 fpm climb rate. But when I got up near the 10000' point, at 110 KIAS, I was only getting around 500 fpm. I haven't done proper climb charts yet, but since I've heard of lots of people cruising in the RV-10 at 15000'-17000', how are they getting up there? My climb was at full rich, as I've been taught to do in lower performing planes - is it standard practice to lean out the mixture in climbs up at that altitude for more power? Or perhaps a slower climb speed/steeper angle than my 110 KIAS?



3. Performance in general: I did some airspeed indicator calibrations today at different power settings at 3200', and ended up with the following true airspeeds: 25"/2500RPM: 150 knots, 24"/2400 RPM: 147 knots, 23"/2300 RPM: 141 knots, 21"/2300 RPM: 134 knots, 18"/2300 RPM: 118 knots, 16"/2200 RPM: 103 knots. These numbers are without wheel pants, but with that in mind, do they seem reasonable? Vans' web site suggests cruise at 171 knots at 75% power at 8000'. I know that claims should be taken with a grain of salt, and I didn't run these tests at 8000', but if my calculations are correct, at 25"/2500 RPM I should have been producing about 80% power. Is it expected that the wheel pants and/or a higher altitude are going to make a significant enough improvement to get closer to Van's numbers?



4. CHT temps: To break in the engine, I've been running it pretty hard - usually around 25"/2500 most of the time (with some cycling to 25"/2600 or down to 24"/2400 to avoid building a ridge in the cylinder). In cruise with those power settings, my cylinders 3 and 4 run comparatively cool at around 375F. Cylinders 2, 5, and 6 are about 410F, but cylinder 1 is a bit of an anomaly. Usually it's the hottest of all, getting up to around 440 (5 degrees hotter than Lycoming's recommendation for maximum service life), though there have been a few times where it's dropped rather abruptly by 50-60 degrees (for no apparent reason I can see), making it surprisingly suddenly the coolest cylinder. But it doesn't stay there - after awhile, it climbs back up to step in line with what cylinders 2, 5, and 6 are doing... but usually stays 20-30 degrees hotter than the rest. Outside temperatures have been around 30-40 Fahrenheit during the flights so far.

Of course, at lower power settings, the CHTs all drop down to well under 400. And all power settings, the engine operation has been very smooth - no roughness at all.

I can reduce the height of the dam in front of cylinder 1, and I've heard of lots of people having to do that. But especially with the strange temperature fluctuations I'm still not sure if it's fully broken in yet, so I've been holding off until things settle. Has anyone else noticed a hot cylinder 1, and if so, how much of the front dam did you remove to cool it down? The good thing is my centre two cylinders seem plenty cool so I should be able to sacrifice some of their airflow to get #1 down.



5. Break in: I've flown the engine pretty hard now for 9 hours, but haven't seen any dramatic sign of CHTs reducing as is supposed to happen with a break in (with that said, the engine was run in at Lycoming for about an hour, and about 45 minutes on the ground under supervision of an aircraft engine shop for further break in before first flight). Other indications like "until the oil consumption has stabilized" haven't helped either - I put in about 3/4 quart of oil at about the 6 hour mark, but that's been it.... so far, it hasn't used excessive oil, and as I've only added oil once, I'm unsure of how to even define "stabilized". Now that I'm at the 9 hour mark for flight (11 hours on the engine overall), should I conclude that the engine is probably broken in about as good as it's going to get, or should I still be holding out for a noticeable drop in CHTs?



Sorry for the long email! But if anyone has any suggestions, advice, or comments on any of these or other issues, I'd certainly appreciate hearing from you!

I'm looking forward to meeting with some of you at fly ins, as soon as I finish flying off the 25 hours I need to do first!

Dan
---
Dan Charrois
President, Syzygy Research & Technology
Phone: 780-961-2213







- The Matronics RV10-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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Kelly McMullen



Joined: 16 Apr 2008
Posts: 1079
Location: Sun Lakes AZ

PostPosted: Sun Jan 29, 2017 6:37 am    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

Big congratulations. Makes all the work worth it. My first flight was last April.

On Sun, Jan 29, 2017 at 6:07 AM, Jesse Saint <jesse(at)saintaviation.com (jesse(at)saintaviation.com)> wrote:
Quote:
--> RV10-List message posted by: Jesse Saint <jesse(at)saintaviation.com (jesse(at)saintaviation.com)>

1. A lot of the RV-10's do this. I know people who have changed out their engine driven pumps thinking they were going bad and nothing changed. The main thing to monitor is if your engine starts leaning out or stumbling because of it. If everything is smooth, then it's not a problem. The pressure at the inlet to the pump has a much different range because it can be sucking the fuel from a substantially lower point (the "-2") or it can be pressurized by the boost pump (the "35"). If stock, you are measuring at the pump outlet. Keep your eyes on it and you should be fine, but it doesn't hurt to run the boost pump for peace of mind.
I suspect that the fuel pressure pickup isn't plumbed correctly, or there is an issue of a restriction somewhere in the lines between the tanks and the fuel servo input. The pressure hose should be connected at the fuel servo. I just went back and looked at my data from a few recent flights.

The only time my fuel pressure drops below 25 psi is when I push the throttle in for take-off, where it may drop to 18 psi for a few seconds before returning to above 25 psi. No change in fuel pressure up to 9800 density altitude, which is highest I have gone in recent flights.

The RSA fuel servo needs 15 psi to work correctly. If the boost pump increases pressure by more than 2-3 psi, the mechanical pump is having to work too hard.

I would be looking for restrictions, such as junk in the fuel filter, a kink in plumbing, etc. Or there could be a small air leak into a fuel line, allowing sucking of air that will reduce fuel pressure, even if there is no leak. The boost pump giving a big boost implies that there is either too much suction needed, or a leak. Early on, I had a few seeps in the lines, wing to  fuel selector to firewall. I went back in tunnel, installed a paper towel at every connection, and made corrections to any that left any fuel traces at all.

I modified my original fuel selector install, to get the valve and lines as low as possible in the tunnel, because you don't want the valve looking like a big inverted siphon that creates potential for vapor lock. Basically spent the money to get extension for the Andair valve so I could move the valve itself down, instead of being up at the top of the tunnel.

Quote:

2. You should absolutely lean out the mixture as you climb. I start leaning by 1,500' usually. I lean the EGT's out to about 100-150 degrees ROP in the climb. You can find this number by seeing what your EGT's peak at. To do this, run 20" and 2400 rpm at 3,000' and lean until they peak. I see most peak at 1,425-1,450. If so, I climb with the hottest cylinder at 1,300-1,325, and keep leaning as I climb to keep it there. I run a little more rich if I need to for CHT's, but I never run WOT much above the pattern. This will make a huge difference in your power, especially as you approach 10,000'. I suspect that 1 and 2 are somewhat related. If you start to lean, your fuel flow will decrease as you climb, and your fuel pump will be able to maintain a higher pressure.
You can start your leaning where ever you choose. I lean generally to maintain EGTs in the 1200 to 1300 range during climb starting at perhaps 3000 MSL, then lean to lean of peak once I level into cruise. It isn't critical exact numbers in climb, just a twist occasionally to keep EGT in that 1200 -1300 range which will be about 150-200 rich of peak. Or if you are near sea level, see what your EGT is shortly after takeoff at full rich. It should be in that range, but use whatever it is at as an upper limit, and stay about 50 degrees cooler than that.

Quote:

3. Some planes are faster than others and some are slower, but I have only seen a total speed fluctuation of less than 10 ktas. The MT prop is slightly slower than the Van's-used Hartzell. Some say it's the same, and others say it's 8 knots slower. It's somewhere in that range. The takeoff and climb is supposed to be better, which I suspect will prove true once you start leaning. The wheel pants and gear leg fairings, in my experience, add about 17 kts. That should get you fairly close to the Van's numbers. I suspect you will I prove speed by leaning. Run the speed tests at 6,000-8,000 density altitude. In my experience the absolute fastest is at about 6,500 density altitude, wide open throttle, matching prop rpm and about 15-16 gph fuel flow. Most RV-10's will get 174-183 ktas in this test.
I agree with Jesse. I have the MT prop. Once I got gear fairings installed, I run about 160-165 TAS at power below 70% and 170-175 above 70% as long as I am above 5500. Speed definitely improves with altitude, while fuel flow decreases as power available decreases. I haven't done finish work on fairings yet, so I may find a couple more knots when I do that and when I get paint done. Your numbers are similar to what I had before I got the wheel pants and fairings installed.

Quote:

4. I suspect you have the air dam in front of Cylinders 1 and 2. Remove the dam from Cylinder 1 to see if that helps. I usually end up leaving those air dams out completely on both 1 and 2. I suspect it will. Then, increase your climb airspeed to lower those temps. Temps will come down as the engine breaks in, but those number are hotter than I like to see. Try to keep them below 400 if possible, and certainly below 420. The fluctuation seems to me to be more of a gauge issue than the cylinder. I assume these temps are all in climb. Take another look through your baffles and seal any spots where air can get to the lower cowl without going through the cylinder fins. These engines usually require at least half a caulk tube of RTV to seal well.
Spot on. I removed the air dams, and then when 5 and 6 ran hot with no dams, used some aluminum tape on front two cylinders to achieve temp balance. I may do small dams to match where I have the tape now. Definitely use power and airspeed adjustments to keep CHT below 400. Your CHT will come down once you get wheel pants on.

Quote:

5. You may still get a decent drop in CHT's, but you may already be broken in most of the way. How high are you keeping your oil? I usually add 8 quarts at a change including the filter, and add a quart when it gets to 6.5. I've seen these engines settle in at 5 hrs/quart to 20+ hrs/quart. It sounds like you are at about 8-10 now. See if that drops.
You will find an oil level that the engine likes. Right now mine is around 6 quarts in the sump. I hope to improve that with an air/oil separator on the breather line. You probably have the engine 80% or more broken in. There will be small improvements perhaps to 25-50 hours, but nothing like the first 5-10 hours. 

Quote:
 
Kelly McMullen

40866 with about 90 hours of flying time

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PostPosted: Mon Jan 30, 2017 6:09 am    Post subject: Re: Another RV-10 flying! (with some performance questions) Reply with quote

I would suggest that you install the wheel pants before you fly again. I had similar issues with high CHTs without them, and after I installed them the temps came down. The additional air flow from the higher airspeed helps kept the cylinders cool. I never let my CHTs climb above 400 deg. I generally climb out at 125kts and reduce power after a safe altitude for an exned climb to 25/25.
My air dams ended up at approx one third of the original height.


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PostPosted: Tue Jan 31, 2017 2:36 am    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

Congratulations Dan

Wishing you safe skies and low temperatures.

Warm regards from downunder.

Patrick

Quote:
On 29 Jan 2017, at 20:04, Dan Charrois <dan(at)syz.com> wrote:



Hi everyone.

I'm happy to say that after 11+ years of work, my RV-10 is finally in the air. As a testament to Van's incredible design (both in terms of the airframe performance and reliability, and perhaps equally importantly, in producing a kit that newcomers to the idea of homebuilding can build safely) , the first flight (and subsequent ones) have been pretty much uneventful. Everything "just works" - the plane handles like a dream and I'm looking forward to spending thousands of hours flying it. Still a ways to go yet - I'm currently at 9 hours of flight time in it Smile

But as nice as the plane seems to be, I'm in the phase right now of analyzing the heck out of everything to make sure it's operating as it should (fortunately, I have some AFS EFISes in there that log data for me to go over afterwards). And though the plane is operating 99% as well as I hoped for, there are a couple of things not operating quite as I expected - I'm after other people's advice to see if they've experienced something similar. Any help or insight anyone can give on any of these issues would be greatly appreciated!

My plane is a pretty standard build with a factory-new Lycoming IO-540 D4A5 and 3-bladed MT prop.



1. Fuel pressure drop climbing to higher altitudes: Today, I did an "informal" climb at 110 KIAS and 2500 RPM/full throttle/full rich to 10000' to see how it would handle it. At around 3200' MSL, I see a fuel pressure of about 21psi with the engine pump (boost pump off). But in the climb, the fuel pressure drops significantly. At 5000', it's at 18psi, at 7000' it was about 16psi, then it started dropping faster. At 8000' it was down to 13psi and by 8700' had dropped down to 11psi. I turned the boost pump back on and it promptly shot back up to 20psi, so I continued the climb to 10000' and then made my way back down. By the time I got back down to 4300' I turned the boost pump off and the engine pump maintained pressure at 22psi. I never did take the chance to level out and test pressure further - without knowing if it was a significant cause for concern, I got back down to the lower altitudes instead. I haven't seen any significant pressure fluctuations in flying a!
round under 5000'.

According to the Lycoming manual, the fuel pressure for the IO-540-D4A5 at the fuel injector is supposed to be between 14 and 45 psi. This is where the Van's stock fuel pressure sensor is measuring, isn't it? Though I've seen at least two other pilot's RV-10 POHs that use numbers for the acceptable pressure to be what Lycoming quotes as that for the inlet to the fuel pump of -2 to 35 psi, so it's got me wondering if I'm misinterpreting either the Lycoming documentation or the fuel plumbing. So the question I have - is that low fuel pressure the cause for concern I think it is? If so, what might be causing it, and how would I fix it? Or is it normal? What do other people see in climb to 10000'? Though I can use the boost pump for climbs to higher altitudes (and I've heard of some certified aircraft that suggest it), it doesn't strike me as an appropriate measure if the boost pump were to fail.



2. Rate of climb at high altitudes: I haven't constructed the wheel pants yet, so I know performance will improve when they're done. At low altitudes I certainly can't complain about rate of climb - with 450 pounds of fuel and me, I did a short field takeoff today climbing out at about 85 knots and saw a 2150 fpm climb rate. But when I got up near the 10000' point, at 110 KIAS, I was only getting around 500 fpm. I haven't done proper climb charts yet, but since I've heard of lots of people cruising in the RV-10 at 15000'-17000', how are they getting up there? My climb was at full rich, as I've been taught to do in lower performing planes - is it standard practice to lean out the mixture in climbs up at that altitude for more power? Or perhaps a slower climb speed/steeper angle than my 110 KIAS?



3. Performance in general: I did some airspeed indicator calibrations today at different power settings at 3200', and ended up with the following true airspeeds: 25"/2500RPM: 150 knots, 24"/2400 RPM: 147 knots, 23"/2300 RPM: 141 knots, 21"/2300 RPM: 134 knots, 18"/2300 RPM: 118 knots, 16"/2200 RPM: 103 knots. These numbers are without wheel pants, but with that in mind, do they seem reasonable? Vans' web site suggests cruise at 171 knots at 75% power at 8000'. I know that claims should be taken with a grain of salt, and I didn't run these tests at 8000', but if my calculations are correct, at 25"/2500 RPM I should have been producing about 80% power. Is it expected that the wheel pants and/or a higher altitude are going to make a significant enough improvement to get closer to Van's numbers?



4. CHT temps: To break in the engine, I've been running it pretty hard - usually around 25"/2500 most of the time (with some cycling to 25"/2600 or down to 24"/2400 to avoid building a ridge in the cylinder). In cruise with those power settings, my cylinders 3 and 4 run comparatively cool at around 375F. Cylinders 2, 5, and 6 are about 410F, but cylinder 1 is a bit of an anomaly. Usually it's the hottest of all, getting up to around 440 (5 degrees hotter than Lycoming's recommendation for maximum service life), though there have been a few times where it's dropped rather abruptly by 50-60 degrees (for no apparent reason I can see), making it surprisingly suddenly the coolest cylinder. But it doesn't stay there - after awhile, it climbs back up to step in line with what cylinders 2, 5, and 6 are doing... but usually stays 20-30 degrees hotter than the rest. Outside temperatures have been around 30-40 Fahrenheit during the flights so far.

Of course, at lower power settings, the CHTs all drop down to well under 400. And all power settings, the engine operation has been very smooth - no roughness at all.

I can reduce the height of the dam in front of cylinder 1, and I've heard of lots of people having to do that. But especially with the strange temperature fluctuations I'm still not sure if it's fully broken in yet, so I've been holding off until things settle. Has anyone else noticed a hot cylinder 1, and if so, how much of the front dam did you remove to cool it down? The good thing is my centre two cylinders seem plenty cool so I should be able to sacrifice some of their airflow to get #1 down.



5. Break in: I've flown the engine pretty hard now for 9 hours, but haven't seen any dramatic sign of CHTs reducing as is supposed to happen with a break in (with that said, the engine was run in at Lycoming for about an hour, and about 45 minutes on the ground under supervision of an aircraft engine shop for further break in before first flight). Other indications like "until the oil consumption has stabilized" haven't helped either - I put in about 3/4 quart of oil at about the 6 hour mark, but that's been it.... so far, it hasn't used excessive oil, and as I've only added oil once, I'm unsure of how to even define "stabilized". Now that I'm at the 9 hour mark for flight (11 hours on the engine overall), should I conclude that the engine is probably broken in about as good as it's going to get, or should I still be holding out for a noticeable drop in CHTs?



Sorry for the long email! But if anyone has any suggestions, advice, or comments on any of these or other issues, I'd certainly appreciate hearing from you!

I'm looking forward to meeting with some of you at fly ins, as soon as I finish flying off the 25 hours I need to do first!

Dan
---
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President, Syzygy Research & Technology
Phone: 780-961-2213







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PostPosted: Tue Jan 31, 2017 5:18 am    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

I don't recall if it was suggested, but you might want to either Tee in a calibrated fuel pressure gauge, or just substitute one to see if your engine monitoring system is reporting fuel pressure accurately. The mechanical pump is used on a variety of engines, a lot of the fuel injected models using the same part number. Both the 4 cyl 200 hp engine on my Mooney and the IO-540 of my -10 use the same pump. They both produce indicated 25-27 psi and the boost pumps increase that by 1-2 psi. While I don't think gascolators on the suction side should create much restriction, who knows. One other thought...the fuel vent line is supposed to have 45 degree cut to slightly pressurize the tank. (section 44-7), . If the tank isn't at atmospheric pressure or better at higher altitude the pump has to work harder.

Easy way to check for air leaks between boost pump and mechanical is to simply turn on boost pump with mixture at cutoff until it reaches max pressure, turn it off, and see how long the system holds that pressure.
-sent from the I-droid implanted in my forearm

On Tue, Jan 31, 2017 at 3:32 AM, Dan Charrois <dan(at)syz.com (dan(at)syz.com)> wrote:
Quote:
--> RV10-List message posted by: Dan Charrois <dan(at)syz.com (dan(at)syz.com)>

Thanks for all the responses, everyone!  And as it turns out, the timing is good for doing some adjustments and tweaks.  Since the weather here is supposed to be not great for a little while, and since it was getting to be about time for the first oil filter inspection/oil change anyway, I think I'll be pulling a few more things apart for inspection while I'm at it.  With 9 hours of initial flight time, I figure it might not be a bad time to give it the equivalent of an annual to make sure everything is working as it should.

With regards to my engine pump, it's somewhat encouraging that some people have also noticed a pressure drop while climbing.  But not everyone seems to - a lot of people have reported very little if any loss of pressure.  Along the way I've learned a lot about how engine fuel pumps work (thanks for the YouTube link, Tim!).  Over the next few days, I'm going to be pulling apart my fuel filters and strainers to see if any contamination or blockages have made their way in (quite possible after construction - and now I certainly hope so, since that would be an easy fix!), and will certainly check for possible kinks or air leaks into the fuel lines too.  I have an Andair fuel selector valve with an extension so the valve is towards the bottom of my tunnel, eliminating at least one potential issue.
  
   


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PostPosted: Tue Jan 31, 2017 12:19 pm    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

I agree in general, however I seriously doubt any vapor is occurring. There is supposed to be a blast tube of cooling air on the mechanical pump, providing ambient air. With a constant flow of fuel the avgas is unlikely to vaporize under 15 psi of pressure. You would have a lot more occurences of low pressure and likely some engine stumbles if there really was vapor. I did a lot of my Phase I at temps above 100 degrees, and had no issues with fuel pressure.

I could see bending the fuel vent lines forward a little to get more pressure into the tank to see if that helped.

-sent from the I-droid implanted in my forearm

On Tue, Jan 31, 2017 at 9:14 AM, Tim Olson <Tim(at)myrv10.com (Tim(at)myrv10.com)> wrote:
Quote:
--> RV10-List message posted by: Tim Olson <Tim(at)MyRV10.com>

At higher altitudes the fuel will vaporize easier.  Additionally, most
of the time while you're climbing the airflow thru the cowl isn't
as good.  So, you have heat buildup causing vapor, and altitude making
vapor easier to form.  With the fuel pump behind the
engine, it's in an area of higher heat.  So, vapor can be a
problem.  There are PLENTY of people who have noticed this
in their RV-10s.  There are some who have not.
I certainly wouldn't replace a fuel pump over it, because it
is common enough that I don't believe it to be highly abnormal.
This has happened to me maybe 25 times or 30 times in
1200 hours...maybe more, but not every flight.  Usually
it happens when I get over 8000'.  Never has the pressure
actually dropped enough that the engine felt it.
I have seen as low as 12PSI.  Leaning for climb helps,
because you reduce the flow which increases the pressure.
Climbing slower helps because you cool better.

I HAVE seen it happen where running the boost pump for 30 seconds
takes care of it and it doesn't re-occur.  Other times it may
come back in a minute or two.  Maybe it's a pocket of vapor
that gets blow thru with the boost pump.  Either way, the
important thing is you know it's happening and most EFIS
systems will audibly alert you.  When I get the alert I
just look at the gauge, turn on the pump, and the problem
is over.

I did buy a fuel pump cooling shroud from Aircraft Spruce at one
with the intent of adding blast cooling to my fuel pump.
I never bothered to install it because it's kind of a
pain to get into that area and install it, or even
replace the fuel pump in the first place.  I decided that
it wasn't worth the effort for an occasional occurrence.

It's not bad that you're going to go thru all the inspection work,
but I wouldn't sweat it too much about the fuel pressure in
climb unless it happens to you all the time.  Try climbing
at 120kts and try a few things before you spend too
much worry over it.

Tim





On 1/31/2017 4:32 AM, Dan Charrois wrote:
Quote:
What I just don't understand though is why at low altitude and high
power settings (25"/2500, and around 20 gph), I'm seeing an OK fuel
pressure of around 22 psi.. but for some reason when I did my climb,
the pressure went way down even though the flow stayed the same.. and
then when I got back to a lower altitude, the pressure went right
back up again.  I'm not sure if it was related to altitude, high
power for an extended period, or climb attitude.  Once I finish going
through the system for leakage, blockages, etc. and get the plane
back in the air, if I'm still having trouble, my plan is to try a
step climb to try and isolate whether altitude or attitude is more
likely causing the issue in the first place.

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PostPosted: Tue Jan 31, 2017 6:23 pm    Post subject: Another RV-10 flying! (with some performance questions) Reply with quote

Hi Dan,
I have just been looking at my numbers from the AFS 4500 System on my Rv10
with the IO-540 D4A5,
Your performance numbers are pretty much the same as mine so when you get
your wheel Pants and Spats sorted out I think you
Will have no trouble getting better than 170 KTAS. The best I have seen on
mine so far has been 173 at 9000 ft WOT.

As for CHTs they seem a bit high from what I am seeing here. I have to
convert my numbers for you because here in VH we
use a Hybrid system where volume and Temp are metric. You don't show Fuel
flow numbers for your figures but at Sea Level
We look for 96 litres /hour which if I convert for you is 25.4 gph.

Climbing to 7500 ft and WOT the highest my CHTs got was around 198 deg C
which is 388 deg F.
This was when the engine had about 25 hours on it. The Delta from OAT of 25
deg (77 F ) was 173 deg C or (311 deg F).
Now that the engine has about 85 hours on it, it is running a little cooler
with the Hottest being 194 C (381 deg F) for a delta of
167 deg C (301 deg F).

So putting a few more hours on it have made the temps come down a bit, by a
around 10 deg F.

By the way I climb out at the approx IAS for max Aerodynamic efficiency
which I have been told is 117 KIAS.
(If someone has an update on that number I would be Interested to know what
you have.)
Anyway a bit more air over the Cylinders makes it a little cooler of course
and if I climb at 85 knots the
Engine does get quite a bit hotter and the temp will climb above my usual
limit of 204 deg C (400 F). Although I haven't tried that
sort of Max performance climb for a while so it may be running a little
cooler at 85 knots now.

As for your #1 Cylinder doing funny stuff, I had my number 2 doing a similar
thing. It would go high at full power
and then flip suddenly to under all the others when I leaned the engine. It
turned out it was a partially blocked
Injector. I couldn't work out what it was in there except that I could see a
very slight whisker of something in the
Orifice when I looked through it. We couldn't get it out with air or an
Ultrasonic Cleaner, so I resorted to a
Very fine piece (much finer than the drill size of the orifice) of copper
wire to poke it out. Problem fixed!

So after all of that check your Fuel flow is above 25 Gph at sea level on
takeoff just to be sure that the Servo
Is giving the Engine enough fuel.
Cheers

John MacCallum
VH-DUU
RV 10 # 41016

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