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billderou(at)yahoo.com
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 Posted: Sat Dec 02, 2006 6:03 pm Post subject: Yet More RV-10 Performance/Efficiency |
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Sorry everyone about the Subie bashing but I simply don't get it and probably should not have answered an email on the subject.
Hi Tim: always good to hear from you.
I have flown only 3 cross-country missions with the RV-10 and am still learning about LOP operations. My engine EGTs max-min is only 30 deg F - so it seems that the fuel injection nozzles are producing similar flows. After many test flights and trimming the front entrance dams I can now control my CHT's. Typically during cruise the cylinder temp max-min is 40 degrees F with an average around 325.
When I fly with over 21" MP the engine feels "rough" to even peak mixture settings. If I fly 20" or under then I can run 20 degrees LOP but the engine feels "starved" (better than rough). Apparently, there is a minimum altitude to reap the fuel flow benefit.
It would seem that the engine will run LOP satisfactory at some high altitude or at some low power setting. However, there is an airspeed drop of approximately 10mph from peak to LOP settings. I should invent some metric to show graphically on my display how efficient the aircraft is flying. TAS divided by gph seems simple, but it would also be useful to bring the prop speed into the equation as it will also affect efficiency. BTW - what prop speed settings are you using during cruise?
My engine just feels smoother, which I translate to healthier, at peak leaning so I have adopted a conservative approach. Perhaps if I pulled the throttle back to the 10mph less point and then leaned LOP the engine would still feel healthy and the speed not drop off. Have you noticed any negatives of running LOP? Are there any negative reports? Lycoming recommends leaning back to peak but I have not seen a statement focused on LOP operation.
Clearly, there is more to flying LOP than simply leaning.
Bill DeRouchey
billderou(at)yahoo.com (billderou(at)yahoo.com)
Flying with a few pit stops
Tim Olson <Tim(at)MyRV10.com> wrote:
[quote]--> RV10-List message posted by: Tim Olson
Hey Bill, I'm not going to join a pile-on about Subies. For the record
I basically agree, but still encourage anyone willing to step forth.
I personally wouldn't buy the finished plane because it isn't what
I'd want, but I meet others who would now and then. If the promises
deliver, I'd think it would be a viable "alternate" engine, but I would
doubt that in the end any of the benefits or deficits would be all
that big one way or another.
What I did want to do though was point out a couple more numbers. Just
today I took a prospective RV-10 buying family up for a demo flight...
that's 3 weekends in a row now. Dad's a retired TWA 767 captain, and
son flies little corporate jets. We stuck mom and son in the back
and climbed out at about 1900fpm thru somewhere in the 4000-5000'
range, and leveled out above a broken layer for some stick time. They
wanted flow numbers and I said to expect 13-14gph running ROP at
that altitude, but more like 10 by running LOP. I pulled it LOP
at reduced power at 6500' (don't usually do it below 8K), and we
quickly had our flow down and were truing at 166Kts True (I added
2 to my number since after testing I'm 2kts low in indication).
8.5gph is easy if you're willing to fly over 10K, and from Jesse's
experiences (they've flown higher on long trips than most of mine),
flows in the 7's aren't hard for them to get either.....If I were
seeing 12gph as you are, I know it would be rich-of-peak....so I
assume that must be how you cruise.
So it was a good little demo flight and the performance shows real
well....'specially this time of year up here. The part that gave
me the biggest kick was having both of the other non-flying pilots
tell me that the power in my panel was far better than in the
jets that either of them fly. It's truly amazing what the
21st century brought, and it's great to have it more available
to us builders than it even is to those who just want to plunk
down a wad of cash on a new certified plane.
I know that wasn't much subie/lyc stuff, and as I said, I don't
really care to pile on. But I do agree with you that the performance,
and reliability, and everything else in an engine is there for me,
so I'm very happy with that. What would be really cool though
is to see Dan's Subie come in as a good performer and light a fire
under the lyc clone companies to keep the competition level high
and bring everyone's price down.
Tim Olson - RV-10 N104CD - Flying
do not archive
Bill DeRouchey wrote:
[quote] What is it the nay-sayers should be surprised about?
Sticking to the hard facts:
I am flying an RV-10 with the Lyc IO-540 260HP as Van recommends.
The power is wonderful. The reliability unquestionable. The engine is
extremely smooth. The engine drops into place with a proven installation.
If the issue is economy, and you consider the Lycoming thirsty, pull the
throttle out to 8.5 gph and the TAS will settle at 150mph true. When its
time to fast and far then climb up to 10-11K with full throttle and fuel
flow will settle to 12gph at 195mph true.
If the issue is power then consider I can takeoff with a very light load
and without crossing the end of a 4000' runway perform a hard, climbing
turn (poor mans Immelman) to downwind and settle at pattern altitude at
mid-field. Or, during my last cross-country we climbed with full tanks,
2 souls, and some baggage from 7500 to 11500 in 4 minutes. Class B
airspace? No worries.
Perhaps the issue is initial expense. If you are able to save money on
the initial engine installation then you will have an RV-10 that is
worth that much less when its time to sell. The number of RV-10 buyers
for used aircraft with an Egg engine could dance on the head of a pin.
Buy Lycoming and the money is only parked for a while and can
be redeemed later upon sale.
Maybe the real issue is the Egg folks are rebels at heart. This is good
as I am a rebel myself. However, I don't mess with the airframe nor
engine. You can be a great rebel by painting the airframe in LSD
rainbows or Playboy nudes. Tile the inside. Pull out the back seats and
install a shallow spa. Glass in a row of upside down surfboard fins
along the fuselage spine and paint sharks teeth under the cowl. Go for
it - I love creativity.
Maybe the issue is you hate Lycoming. Everybody has bad experiences. I
can't help you with this one.
So ... help me get it, but stick to facts.
Bill DeRouchey
billderou(at)yahoo.com
Flying with a few pit stops
*/millstees(at)ameritech.net/* wrote:
-Les:
I think that should read "about to deliver 14 RV-10 Engines". He
has 14 engines sold, mine among them, for delivering in the
December-January time frame. To the best of my knowledge, the other
engines sold for the RV-10, are for '07 delivery. My -10 is a year
or better away from flying, however, I think Dan Lloyd is much
closer, and will probably be the first RV-10 with the Subaru engine
to fly. I am, obviously, looking forward to the first airplane to
fly, and am expecting all the nay sayers to be suprised.
Steve Mills
RV-10 40486 Slow-build
Naperville, Illinois
finishing fuselage
Do Not Archive
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Tim(at)MyRV10.com
Guest
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| Posted: Sat Dec 02, 2006 7:07 pm Post subject: Yet More RV-10 Performance/Efficiency |
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Hey again Bill,
Strange that you get rough running at those higher MP's. What
injection system is it...mine's the vanilla Silverhawk Precision
(bendix)? I don't know that there's a min. altitude so much
as a max power setting, but yeah, I typically don't bother
if I'm under 7,500', but on any x/c, that's a typical min.
altitude anyway. (except for the trips when I've been stuck
at 1200' AGL....those I just suck it up and burn lots more gas)
As for prop speed, coincidentally, when Vic and I flew eachother's
planes, I was quite surprised to see that he says his feels best
at 2360rpm. Totally un-coordinated, I had been playing with RPM's
for months previous and found that 2360 seemed to be a sweet feeling
spot as well. Who knows, maybe there's a good harmonic there.
I can cruise at 170-172kts running ROP and then switch to LOP and
get great flows and still pull 165-166kts. If I'm willing to run
even more LOP (closer to 50-75 deg), I can get the flow back another
gallon almost, but I'll be down to 152-156kts doing it. So I'm
usually 25-50 LOP. I don't notice any difference in smoothness,
but just a drop in speed. You then feel the difference in power
if you richen it up after a while...once you get used to the feel,
the sudden increase in power is very noticible. So yes, I do
know that I'm sacrificing a little speed. But as Jesse so perfectly
pointed out way back, with that loss in speed comes great leaps
in distance traveled...so if you can skip just one gas stop, you'll
save a TON of time, and lots of fuel too when you don't have to
climb back up into cruise. When I took off for home on my last
big trip, I was 300nm+ into the trip and still showed 700nm+ of
range left....and I was cruising in the mid 160's at 13K'.
I haven't noticed any negatives. Clean plugs at 170 hours,
and great LOP CHT's, so actually, I've only seen positives so
far. Only time will tell on how long it goes to TBO +/-. My
gut is telling me it looks like a great thing right now....or
maybe that's my pocketbook, as I've already saved enough to
afford a cylinder or two. 
There's actually a bunch about leaning out there on the net.
The big thing about it is, it's another personal choice thing. You're
going to find people well ingrained in either camp, and people will
preach one way or the other. I never ran my last plane LOP (couldn't
as it was a carb engine), but this plane I did after a few dozen
hours and now I'm convinced that it is definitely for me.
Here's a good article to start you off: http://www.taturbo.com/future.html
Tim Olson - RV-10 N104CD - Flying
do not archive
Bill DeRouchey wrote:
[quote] Sorry everyone about the Subie bashing but I simply don't get it and
probably should not have answered an email on the subject.
Hi Tim: always good to hear from you.
I have flown only 3 cross-country missions with the RV-10 and am still
learning about LOP operations. My engine EGTs max-min is only 30 deg F -
so it seems that the fuel injection nozzles are producing similar flows.
After many test flights and trimming the front entrance dams I can now
control my CHT's. Typically during cruise the cylinder temp max-min is
40 degrees F with an average around 325.
When I fly with over 21" MP the engine feels "rough" to even peak
mixture settings. If I fly 20" or under then I can run 20 degrees LOP
but the engine feels "starved" (better than rough). Apparently, there is
a minimum altitude to reap the fuel flow benefit.
It would seem that the engine will run LOP satisfactory at some high
altitude or at some low power setting. However, there is an airspeed
drop of approximately 10mph from peak to LOP settings. I should invent
some metric to show graphically on my display how efficient the aircraft
is flying. TAS divided by gph seems simple, but it would also be useful
to bring the prop speed into the equation as it will also affect
efficiency. BTW - what prop speed settings are you using during cruise?
My engine just feels smoother, which I translate to healthier, at peak
leaning so I have adopted a conservative approach. Perhaps if I pulled
the throttle back to the 10mph less point and then leaned LOP the engine
would still feel healthy and the speed not drop off. Have you noticed
any negatives of running LOP? Are there any negative reports? Lycoming
recommends leaning back to peak but I have not seen a statement focused
on LOP operation.
Clearly, there is more to flying LOP than simply leaning.
Bill DeRouchey
billderou(at)yahoo.com <mailto:billderou(at)yahoo.com>
Flying with a few pit stops
*/Tim Olson <Tim(at)MyRV10.com>/* wrote:
Hey Bill, I'm not going to join a pile-on about Subies. For the record
I basically agree, but still encourage anyone willing to step forth.
I personally wouldn't buy the finished plane because it isn't what
I'd want, but I meet others who would now and then. If the promises
deliver, I'd think it would be a viable "alternate" engine, but I would
doubt that in the end any of the benefits or deficits would be all
that big one way or another.
What I did want to do though was point out a couple more numbers. Just
today I took a prospective RV-10 buying family up for a demo flight...
that's 3 weekends in a row now. Dad's a retired TWA 767 captain, and
son flies little corporate jets. We stuck mom and son in the back
and climbed out at about 1900fpm thru somewhere in the 4000-5000'
range, and leveled out above a broken layer for some stick time. They
wanted flow numbers and I said to expect 13-14gph running ROP at
that altitude, but more like 10 by running LOP. I pulled it LOP
at reduced power at 6500' (don't usually do it below 8K), and we
quickly had our flow down and were truing at 166Kts True (I added
2 to my number since after testing I'm 2kts low in indication).
8.5gph is easy if you're willing to fly over 10K, and from Jesse's
experiences (they've flown higher on long trips than most of mine),
flows in the 7's aren't hard for them to get either.....If I were
seeing 12gph as you are, I know it would be rich-of-peak....so I
assume that must be how you cruise.
So it was a good little demo flight and the performance shows real
well....'specially this time of year up here. The part that gave
me the biggest kick was having both of the other non-flying pilots
tell me that the power in my panel was far better than in the
jets that either of them fly. It's truly amazing what the
21st century brought, and it's great to have it more available
to us builders than it even is to those who just want to plunk
down a wad of cash on a new certified plane.
I know that wasn't much subie/lyc stuff, and as I said, I don't
really care to pile on. But I do agree with you that the performance,
and reliability, and everything else in an engine is there for me,
so I'm very happy with that. What would be really cool though
is to see Dan's Subie come in as a good performer and light a fire
under the lyc clone companies to keep the competition level high
and bring everyone's price down.
Tim Olson - RV-10 N104CD - Flying
do not archive
Bill DeRouchey wrote:
> What is it the nay-sayers should be surprised about?
>
> Sticking to the hard facts:
>
> I am flying an RV-10 with the Lyc IO-540 260HP as Van recommends.
>
> The power is wonderful. The reliability unquestionable. The
engine is
> extremely smooth. The engine drops into place with a proven
installation.
>
> If the issue is economy, and you consider the Lycoming thirsty,
pull the
> throttle out to 8.5 gph and the TAS will settle at 150mph true.
When its
> time to fast and far then climb up to 10-11K with full throttle
and fuel
> flow will settle to 12gph at 195mph true.
>
> If the issue is power then consider I can takeoff with a very
light load
> and without crossing the end of a 4000' runway perform a hard,
climbing
> turn (poor mans Immelman) to downwind and settle at pattern
altitude at
> mid-field. Or, during my last cross-country we climbed with full
tanks,
> 2 souls, and some baggage from 7500 to 11500 in 4 minutes. Class B
> airspace? No worries.
>
> Perhaps the issue is initial expense. If you are able to save
money on
> the initial engine installation then you will have an RV-10 that is
> worth that much less when its time to sell. The number of RV-10
buyers
> for used aircraft with an Egg engine could dance on the head of a
pin.
> Buy Lycoming and the money is only parked for a while and can
> be redeemed later upon sale.
>
> Maybe the real issue is the Egg folks are rebels at heart. This
is good
> as I am a rebel myself. However, I don't mess with the airframe nor
> engine. You can be a great rebel by painting the airframe in LSD
> rainbows or Playboy nudes. Tile the inside. Pull out the back
seats and
> install a shallow spa. Glass in a row of upside down surfboard fins
> along the fuselage spine and paint sharks teeth under the cowl.
Go for
> it - I love creativity.
>
> Maybe the issue is you hate Lycoming. Everybody has bad
experiences. I
> can't help you with this one.
>
> So ... help me get it, but stick to facts.
>
> Bill DeRouchey
> billderou(at)yahoo.com
> Flying with a few pit stops
>
> */millstees(at)ameritech.net/* wrote:
>
> -Les:
>
> I think that should read "about to deliver 14 RV-10 Engines". He
> has 14 engines sold, mine among them, for delivering in the
> December-January time frame. To the best of my knowledge, the other
> engines sold for the RV-10, are for '07 delivery. My -10 is a year
> or better away from flying, however, I think Dan Lloyd is much
> closer, and will probably be the first RV-10 with the Subaru engine
> to fly. I am, obviously, looking forward to the first airplane to
> fly, and am expecting all the nay sayers to be suprised.
>
> Steve Mills
> RV-10 40486 Slow-build
> Naperville, Illinois
> finishing fuselage
> Do Not Archive
>
> --
| | - 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:
http://www.matronics.com/Navigator?RV10-List |
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coop85(at)bellsouth.net
Guest
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| Posted: Sat Dec 02, 2006 8:28 pm Post subject: Yet More RV-10 Performance/Efficiency |
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Just to chime in FWIW, I also run around 2320 RPM as it feels better than
2400 or more, might be the prop combination or something I don't know
anything about but it is an interesting coincidence that several folks are
gravitating toward the same RPM because it feels right. I'll try 2360 next
time just for fun.
I've been running a lot of LOP at 6,000+MSL and think it's great. With only
an hour left on one flight I did some comparisons and it was going to cost
me 4 gallons to save 7 minutes if I pushed it up - clearly not worth it. I
get about 170-172 ROP (~14.5GPH) and 160-162 LOP (~10.6 GPH).
Marcus
40286
--
| | - 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:
http://www.matronics.com/Navigator?RV10-List |
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