RV-10 Service Ceiling

I bought a completed RV-10 last November with a Lycoming IO-540 (260 HP) engine. I typically have been flying in the 5,000 to 10,000 foot range but wondered if I would be better off flying higher and taking advantage of the winds and better fuel economy. On the Van's website they "estimate" that the service ceiling for the RV-10 (with 260hp) is FL240. I am sure that most of you know that service ceiling is defined as where the airplane is climbing at a max rate of 100 fpm. To fly up at anything above 14,000 you of course need supplemental oxygen. This was a catch 22 for me. I needed the oxygen to see how high I could climb but I didn?t want to purchase a oxygen system if the performance did not warrant it. I fortunately was able to borrow a bottle for my test flight. I guess I could have done it when it was cooler and had better results but I wanted to get on with it and that happened to be at 12 noon one day last week when the OAT was 81 degrees at take-off. I figured that I would run out of manifold pressure before anything else so I kept track of it from 6,000 feet up (results below this note). I started using the oxygen at 10,000 feet and continued a VFR climb to 17,500. I called Oakland Center and requested a IFR clearance and a climb to FL200. I explained that I was doing a test flight in an experimental aircraft to determine the service ceiling. I did have to change frequencies to get the high sector controller but they accommodated me immediately and I was cleared to FL200. They were giving me vectors to say out of everyone else?s way so I did have increased ?G? loads every time I made a turn in the racetrack pattern. Out of FL180 I had to click off the TruTrak auto-pilot because it was having a hard time at that altitude. When I got to 18,800 feet I was still climbing at a rate of about 300 fpm but the engine was misfiring every once in awhile and I was in a very nose up attitude indicating 90 MPH. I decided that I had gone as high as I wanted under those conditions and asked for a descent out of the class A airspace. I kept a very close eye on all of the engine instruments during this trial and the engine RPM was always pegged on 2700 RPM. Although I was still climbing at 300 fpm and was indicating 90 MPH I don?t think I could have gotten above FL195. I have to wonder how Van?s came up with their estimate of FL240 for the 260 HP engine. Has anyone else tried to find out what the service ceiling is on their 10 by actual flight testing like this?

Alt MP
6,000 23.5
7,000 22.5
8,000 21.5
9,000 20.9
10,000 19.9
11,000 19.2
12,000 18.5
13,000 17.8
14,000 17.0
15,000 16.3
16,000 15.6
17,000 14.9
17,500 14.6
18,000 14.3

Why would you run at 2700 RPM?

I did my testing during phase I. 21,100 at gross weight (2800 at takeoff), aft CG. No wheel fairings.

I think I could have gotten a little higher and still maintained 100feet/min...

Cold Spring day.

I normally cruise on cross country at 14,000 - 16,000. Live in Utah, so CC below 10,000 is not very practical.

I have built in O2.

DJP said:

When I got to 18,800 feet I was still climbing at a rate of about 300 fpm but the engine was misfiring every once in awhile and I was in a very nose up attitude indicating 90 MPH.

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Curious why the engine was missing. Were you leaning the mixture?
I took mine to 17,500 during phase 1 with no problems at all. I could have gone quite a bit higher but Minneapolis Center was very busy that afternoon, so I decided not to bother them.
I routinely fly cross country at 10K to 13K. The airplane does very well at higher altitudes.

High altitude will show up ignition system weaknesses. E.g., carbon in the mag can cause it to misbehave. Same for the ignition harness.

Guys, I would be careful stating publicly that you went above 18,000 in phase 1. My phase 1 limitations said "day, VFR", not "day, VMC".

Note to DJP:
Living in northern CA not having O2 is a real limitation if you frequently fly east, over the Sierras. Even when it is clear, flight at the oxygen altitudes is frequently much smoother than down "low" (12000) where you are close to the terrain.

NOT phase 1

This was not a phase 1 test, just a "test" to see how high it would go according to the OP.



The pic is of his RV-10 used for the test and I believe it has accumulated several hundred hours.
I'd be curious as to what caused the "misfiring" as you stated.

I was referring to one of the other posts.....

I really can't see the point above about FL160, and only 170 at a pinch. If you need to go that height to get out of weather....you should stay at home!

As for missing, you need your plugs mags and everything going for you up there.

Leaning, well I would suggest lean to best power, once above 10'000 and be sure you are not too rich.

The RV10 sweet spot is from 7000-14000 I find.

Be careful up there!

Geico266 said:

Why would you run at 2700 RPM?

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Unless I missed something during my initial checkout in the RV-10 I have been led to believe that take-off and climb is done at full power and 2700 RPM. Since I am "climbing" to see what the maximum Alt is that the aircraft with reach I am using the climb power setting. I was not cruising, I was climbing that is why the RPM was at 2700 RPM. Any other ideas, suggestions, comments?

DJP said:

Unless I missed something during my initial checkout in the RV-10 I have been led to believe that take-off and climb is done at full power and 2700 RPM. Since I am "climbing" to see what the maximum Alt is that the aircraft with reach I am using the climb power setting. I was not cruising, I was climbing that is why the RPM was at 2700 RPM. Any other ideas, suggestions, comments?

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At that high of altitude I would think coursing the prop out would help performance. I have cruised many hours above 15k at 2250 with very good performance numbers.

dmaib said:

Curious why the engine was missing. Were you leaning the mixture?
I took mine to 17,500 during phase 1 with no problems at all. I could have gone quite a bit higher but Minneapolis Center was very busy that afternoon, so I decided not to bother them.
I routinely fly cross country at 10K to 13K. The airplane does very well at higher altitudes.

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Mine also went to 17.5 with no problem and I was still using the auto pilot it was so stable. I started out climbing at a modest rate of 1500 fpm then reduced it to 1000 fpm and was probably still doing about 600 fpm when I leveled at 17.5 It was out of FL180 that I started to really notice the engine miss and the rate of climb drastically reduced. No, I never leaned the mixture, I wanted as much fuel as I could get into the engine. Below FL180 the performance is very good and I can see that I can easily cruise in the 15,000 to 17,000 range. I was just surprised at the lack of performance above FL180.

Geico266 said:

At that high of altitude I would think coursing the prop out would help performance. I have cruised many hours above 15k at 2250 with very good performance numbers.

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Cruising and climbing are two very different animals. At cruise you reduce prop RPM to take a bigger bite of the air during each and every revolution of the engine and you can do that because you are no longer "going up hill". The old bicycle analogy works fine in the example. You don't what to be in HIGH gear (reduced prop RPM) trying to peddle up the hill but once you get to the top you can. You want to be in "low gear" as long as you are climbing. Once you get to where you are going (cruise Alt) you can and should reduce RPM and MP and you can have some great performance numbers.

If you were full rich @ 18K I would be surprised if it didn't miss. You have exactly half the oxygen available a sea level.

RV10inOz said:

I really can't see the point above about FL160, and only 170 at a pinch. If you need to go that height to get out of weather....you should stay at home!

As for missing, you need your plugs mags and everything going for you up there.

Leaning, well I would suggest lean to best power, once above 10'000 and be sure you are not too rich.

The RV10 sweet spot is from 7000-14000 I find.

Be careful up there!

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You seem to have missed the entire point of the forum post and the test flight. It was for one purpose and one purpose only and that was to establish what the service ceiling for MY RV-10 is. I know what Vans has publish and I have seen some other numbers floated around but I wanted to know what MY machine would do. I have spent the majority of my life above FL310 so it was not for the thrill of going up high or getting over the weather or ANY OTHER reason as you suggest. I started off my post with "I typically have been flying in the 5,000 to 10,000 foot range but wondered if I would be better off flying higher and taking advantage of the winds and better fuel economy." In order to do that I needed to find out what the performance of this particular machine is and there is only one way to do that, which was to fly the flight.

DJP said:

Cruising and climbing are two very different animals. At cruise you reduce prop RPM to take a bigger bite of the air during each and every revolution of the engine and you can do that because you are no longer "going up hill". The old bicycle analogy works fine in the example. You don't what to be in HIGH gear (reduced prop RPM) trying to peddle up the hill but once you get to the top you can. You want to be in "low gear" as long as you are climbing. Once you get to where you are going (cruise Alt) you can and should reduce RPM and MP and you can have some great performance numbers.

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I was confused by your post. You said you asked to descend and maintained 2700rpm. It didn't sound like you ever "shifted" .

DJP,

Please do not take offense but it sounds like you are used to modern turbine engines where a computer takes care of everything for you, you just set the power. Unfortunately the piston engine you now fly is nothing like that, and you need to review either on your own or with someone who knows engines (and there is a lot of hearsay and old wives tales out there) how to operate them.
But you will find universal agreement on this: full rich at 17000' will be nowhere near the best power mixture setting. I think it's amazing the engine ran at all, you were drowning it in fuel it couldn't burn because of the lack of oxygen, given the low air density at that altitude. That totally explains the missing, some cylinders were so over rich they wouldn't ignite.

The question on the RPM was this: the prop was optimized by Hartzel for cruise, probably around 2400 or 2500 rpm. Is it possible that at an RPM less than 2700 that the increased prop efficiency more than makes up for the loss of engine power? some have claimed the answer is yes.

Note to Oz: Here in CA 17000' sometimes is less than 3000' AGL, so it gives you some gliding range should things go bad.

I often fly my Cessna 180 at altitudes between 14,000 and 18,000 feet. Out here in the U.S. west, it's often necessary to do that to be clear of clouds and terrain. Sometimes 18,000 feet isn't enough but that's another topic.

DJP's experience, with dwindling indicated airspeed and manifold pressure, is exactly what to expect. True airspeed is still decent, of course. Fuel flow rate decreases along with the decrease in manifold pressure because there's less air to burn it.

It's necessary to lean for best power to climb well. The improvement is significant. Plan on doing it repeatedly as you climb. And it's also necessary to rum at full throttle (normally aspirated motor) and maximum continuous rpm to generate the maximum available power to climb.

I expect that with proper leaning, Van's service ceiling would be met.

For descents, my experience, again, is with my 180. The RV-10 might differ. But I find that unless I decrease power to the bottom of the green on manifold pressure and rpm, it's very difficult to descend. On my plane that's 15" and 2,100 rpm. If you can run your engine below that it'll help. Part of the difficulty is that due to turbulence, I like to keep my speed to the beginning of the yellow arc at 160 mph. That's considerably faster than gust penetration speed but any slower and I'd not be going down. I also like to maintain a maximum rate of descent of 500 fpm for comfort.

Sometimes I slip the plane to increase the descent rate - why? Because sometimes I'm descending through lift.

Yes, you have to periodically enrichen the mixture as you descend. I forgot once, on a descent from 9,000 feet to about 1,000 feet, and the engine quit on short final. It was an excellent reminder.

Dave

aerhed said:

If you were full rich @ 18K I would be surprised if it didn't miss. You have exactly half the oxygen available a sea level.

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I agree. You would definitely need to be leaned to climb that high. I also agree that a high prop RPM is appropriate for climb. Low RPM at cruise is fine.

You could find that a slightly courser pitch is more efficient, when chasing every last ounce.

Pierre in some of his speed racing has found a sweet spot that is not quite 2700 RPM, but he is rather tight lipped about exactly where

Not quite

Oz, 2630 RPMs gave the fastest cruise at WOT and 800' ASL!

I can't help with high altitude stuff since my -10 has never been over 10,000' since I've owned it.

Best,

DJP said:

Cruising and climbing are two very different animals. At cruise you reduce prop RPM to take a bigger bite of the air during each and every revolution of the engine and you can do that because you are no longer "going up hill". The old bicycle analogy works fine in the example. You don't what to be in HIGH gear (reduced prop RPM) trying to peddle up the hill but once you get to the top you can. You want to be in "low gear" as long as you are climbing. Once you get to where you are going (cruise Alt) you can and should reduce RPM and MP and you can have some great performance numbers.

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If you were full rich at the altitude you were drowning the engine in fuel and way down on power. If you tried it again with proper leaning I think you would find the aircraft did much better.

George

pierre smith said:

Oz, 2630 RPMs gave the fastest cruise at WOT and 800' ASL!

I can't help with high altitude stuff since my -10 has never been over 10,000' since I've owned it.

Best,

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SSSHHHHHHHHHH now your secret is out!

Funny you say that, my CSU is set to exactly that RPM, I would be fibbing if I said by design, more like sheer fluke.

It climbs and goes well!

Headed your way in under 48 hours..... Look Out!!!

The Air up there...

Guys,

My good friend and Missionary Pilot Steve Saint is probably one of the few RV10 Pilots who regularly uses his RV-Vision Ten for business travel. Their Missionary Organization ITEC built their RV-10 in Ecuador as a mission platform. It has 120 Gallons of fuel, a stock 260HP IO-540, Slick Mags and Hartzell BA with on-board O2.
Steve and two other pilots routinely flight plan at 15-17K and Steve commented "the 10 flies great up high, 15K-17K". From their home base in Central FL they can go non-stop to OSH, TX, and have flown it to Ecuador.

Jesse Saint can answer any questions about performance.
http://www.saintaviation.com/
V/R
Smokey

PS: Recently Steve was injured in an accident and is recovering. More information is available on the website.All your thoughts and prayers are appreciated.

www.itecusa.org

PSS:My RV10 experience was delivering one coast to coast across the US. I flew at 12.5-14.5 at full throttle and 2550 RPM/11GPH LOP/165KTAS.

why 2700rpm

Take off at 2700rpm until 1000AGL, than pull the RPM back to 2500rpm for the rest of the climb. Lycoming states you can run 2700rpm forever but it would be like running your car engine near redline when shifting gears would be better, less wear, per se. Think of it this way. As a runner one starts out with shorter step as well as climbing a hill, but as the road smoothes out and the momentum is faster the steps become larger. Same with the engine 2700rpm to get you started than down to 2500rpm once there is some speed at 1000 AGL and less need for smaller bits of air. Once at cruise than the prop can come down to 2200-2400, or whatever you engine likes most.
In my mind, why make a prop go faster when slower rpm will give you more efficient use of the constant speed prop.
Pascal
RV-10

DJP said:

Cruising and climbing are two very different animals. At cruise you reduce prop RPM to take a bigger bite of the air during each and every revolution of the engine and you can do that because you are no longer "going up hill". The old bicycle analogy works fine in the example. You don't what to be in HIGH gear (reduced prop RPM) trying to peddle up the hill but once you get to the top you can. You want to be in "low gear" as long as you are climbing. Once you get to where you are going (cruise Alt) you can and should reduce RPM and MP and you can have some great performance numbers.

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DJP

I suspect you are close to me and I will be glad to instruct and teach you about your engine and High Altitude.

I fly a Saratoga and in the process of building a 10. I am partners in the Saratoga and we fly out of the Nut Tree in northern ca. if you fly over I will show you how to determine your best power setting and egt for that setting. We can go do this in the Saratoga and then in your 10.

It is very easy to learn and why it is important to use best power in climbs.

I am a a&p mechanic for over 30 years now and have been flying high altitudes since I was 16. I am also a retired US Air Force Flight Engineer, It is much smoother up higher and i think more enjoyable. Just remember O2.

Just let me know if your interested,

Best way to contact me is my e-mail [email protected] or my cell 707-479-5895

John, when you gonna come up to Cameron Park and see the 10??

Or should I fly down there?

Service Ceilings and Speeds

I have about 220 hours in less than 2 years on my -10, and finally have the wheelpants on. This plane is my first with a CS prop and I am still getting used to, and surprised by adjustments in MP and RPM. I have flown from Virginia to Oregon, and from Oregon (my base) to OSH and back already, in addition to trips to the Bay Area and Seattle. It's a kick to fly.

My configuration is a little less standard than most - I have an O-540-B4A5 235 HP engine and the Hartzell prop that is vibrationally matched to the engine, earning me the 25 hour fly-off. My max rpm is 2575 rather than 2700 and it is a low compression engine (I can and do use autogas happily). My fuel efficiency and speeds are slightly less than 'standard.' I always see an average of 12 gph, but I had been cruising at 2400 rpm, roughly 24" MP. I discovered only recently that I could drop back to 2300 rpm and 23" at height (8500+) and get no change in TAS, so I will have to run the measurements again but expect that I will see better efficiency. I expect that this will be my 'economy cruise' setting. And I ALWAYS lean with altitude.

Cross-country handling at 10-14K is just fine - very stable - and same efficiencies. Looking into a (medical) oxygen system with cannula and tubing for under $150 for upcoming trip to KOSH.

Another test flight is in order!

Thanks to all of you that have responded to my post on the Service Ceiling test. I have found it very useful and informative, especially the part about leaning in the climb. It makes perfect sense now that I see it but I didn't think about it at the time. Normally when climbing to 7-8 thousand feet I keep the mixture at full rich until I level off, then I adjust the MP, prop RPM and then the mixture. I never thought about leaning in the climb when I got to the higher altitudes. That also probably accounted for the engine starting to miss around FL180. I guess all of this information calls for a NEW TEST FLIGHT using the insight I have received. Now that I have done it once I will do it again when it is closer to the STANDARD temp and not when it is 21 degrees over standard. Stay posted, I will let you know if the "missing" is eliminated and I get closer to the Van's service ceiling by leaning.

Here's a simple suggestion from John Deakin, author of the Pelican's Perch Column on AVWEB:

"Do you ever note your EGT shortly after liftoff, during the first 1,000 feet of climb (at sea level)? You should, and here's why.

If your engine is set up for the correct fuel flow at sea level and full power, and you note that EGT shortly after takeoff, you have a good EGT setting for the rest of the climb. Simply tweak the mixture knob to roughly that EGT from time to time during the climb, and you will get excellent results, both in terms of economy and safety for the engine.

Note the simplicity? Full throttle, full prop, full rich for takeoff. Tweak the mixture knob now and then in the climb for a loose "target EGT." That's it! No tweaking the MP every thousand feet to bring the MP back up to some oddball MP setting that never made sense in the first place. "

Here's the links to the 4 articles which I consider priceless:

Part 1 - Where Should I run my engine?http://www.avweb.com/news/pelican/182179-1.html

Part 2 - The Climb http://www.avweb.com/news/pelican/182176-1.html

Part 3 - Cruise http://www.avweb.com/news/pelican/182583-1.html

Part 4 - Descent http://www.avweb.com/news/pelican/183094-1.html

Leaning in the climb

Todd

Your statement is totally right. Sea Level standard day take off egt will goive you the best fuel mixture for the climb, and EGT is nothing but a measure of fuel mixture.

I have done this and have used it for years. Works awesome.

On high altitude departures i allways set egt on take off to the egt for sealevel which in the Saratoga is about 1350 egt and you can really hear and feel the performance difference in the plane. I wish Instructors would teach this to there students when giving high performance instructions.

Come and visit.

Mike

I have been swamped with family obligations the past year. Then the annual was due by the end of June along with my medical and BFR, So June was crazy.

Well make ya a deal you fly to Vacaville and I will buy the Ice cream at Fentons next to the field a great lunch stop my treat.

Just let me know when you might have a few open hours to come and visit.

Thanks again for the offer.

John, your TARGET EGT method is 100% correct for take off at high fields, however once flying above 10k you might as well use around 75ROP in he climb, you want best power and the low power state means it is not necessary to have that richer mixture.

As you climb though every 2000 feet it pays to refind peak again

I have found that if I set around 37LPH going through something like 12k I just take a shallow LOP climb.

It is less effort and makes very little difference overall.

The RV Ten is an awesome aircraft

my experience

i flew at 17,500 all the way from texas to nova scotia one time with two fuel stops, engine ran fine even with the junk slick mags that I put on there, The best high altitude mags are the bendix 1200 series, they put those in most if not all turbo airplanes. I could still get close to 500 fpm but my airplane was extremely light. the problem with flying that high is that you have no power so you dont go any faster but you do get extremely good fuel economy and if winds are favorable you could do well. i was doing 180 knots gs because of the tailwind with my indicated somewhere near 100 knots. i was burning 5.2 gallons per hour. If i were ifr rated i wouldve gone higher.
just a tip if you get an oxygen bottle use a medical regulator and valve so you can get filled cheap. dont buy the aviation setup because they are expensive to fill at airport.

Engine management

Don, I would be happy to go with you and show you some of the techniques I have used on my IO 540 in the last 800 hours. I think you may get a significant increase in power by leaning out at higher altitudes, and reducing rpm's a couple of hundred may help too. It takes several flights to get good performance data. I remember getting very significant climb performance going through 21 K ft with my IO 540. Even my old 160 hp RV4 was getting 400+ fpm at 18 K, at close to gross.

Steve

RPM - Be Airport Friendly

At 2700 RPM some props make a lot of noise, please be airport friendly and pull it back at a safe altitude around built up areas. 25 squared is a good climb power until 3000' AGL.

Correct me if wrong but I believe the tips of longer props may approach the speed of sound at max RPM and lose efficiency so 2630 RPM may perform better than 2700.

George

25 squared is a good climb power until 3000' AGL.

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That is bad advice, it is an old wives tail from way back when, however this only reduces performance and raises CHT.

Better to leave it at 2700 and WOT unless your prop is noisy one, some of the 185's with big three bladders make an awful noise.

In these cases just pull a few RPM, maybe 50-100 even, and leave the MP alone. Mixture will be where it should be and everyone will be happy.