|
I feel better now. That lines up pretty well with the
191 true I measured at 8500'. Still would like to duplicate that 2000+fpm
though.
Mike
Sent: Wednesday, February 10, 2010 2:36 PM
Subject: [FlyRotary] Re: rpm vs Power was : Throttle limits was Re:
N.A. Renesis to turbo
Jeff,
I have seen 194 mph true air speed on the EM-2. My
GPS also was showing the same number. I only went full throttle for
about 5 minutes traveling both north and south. I believe this was at
around 7,000' alt. I have never tried to get max. speed at
500' - I guess I am a little chicken to run full out down low. Maybe
I'll do it this spring.
Dennis H.
Jeff Luckey wrote:
Dennis,
What is your top
speed?
From: Rotary motors
in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Dennis
Haverlah
Sent: Tuesday,
February 09, 2010 14:50
To:
Rotary motors in aircraft
Subject: [FlyRotary] Re: rpm vs Power was
: Throttle limits was Re: N.A. Renesis to turbo
Ed, did you trim your propeller to less than
76 in. dia? I thought you or Tracy had trimmed one to 74 in.
I've been flying my Renesis RV-7A for almost 3 years. My
static is about 5200 rpm and top end in flight is around 6300
rpm. I have the 2.85:1 drive on my Renesis a Catto 76 in dia. and
88 in pitch composite and a very quiet exhaust on a Van's RV-7A. I had
fabricated the intake using the original Renesis 4 port intake. I
cut it off just above the secondaries and added a plunum with a Mustang
throttle body. Last spring I replaced the intake with a new intake
designed with Ed Anderson's much needed assistance. The new intake
really improved the take-off, climb and top end performance. The new
intake uses dynamic ram effect - the reflected pulse from the closing of one
rotor intake causes a compression wave to bounce off the side of the rotor and
the tube lengths are such that the pulse arrives at the other rotors intake
port just before it closes. My top end RPM increased from about
5800-5900 to 6300 with the new intake. I now see climb rates above 2000
fpm at 100 kts. See attached photos of the old and new
intake.
Ron, you mentioned temperatures of water - 185F and oil 205F at
8000' I normally see 20 deg. delta. between oil and water with oil
hotter like yours - but I don't see oil temp. above 200 in the summer.
If you are getting 205 oil in the winter it will probably be much too
hot in the summer. Temps are about linear with outside temp -
a 25 deg increase in outside temp will add about 25 to both oil and
water! Also with your prop turning 2450 rpm, the engine would be turning
6980 rpm. I'd think you would be going much faster than 174 mph at that
rpm with the same prop, engine and gear drive as I have. Tracy, if you have the
data could you give us the RPMs you saw at the 205 and 217.5 air
speeds?
Dennis H.
Renesis RV-7A
Austin, Tx.
Ed Anderson
wrote:
Good
point, Tracy
I had one instance
where I my static and top end rpm were essentially the same. I had a
static of 6000 rpm and a top end in flight of around 6100 rpm. But, in
my case, the cause was very obvious – my muffler of the time was limiting the
top end to my static rpm. Once I changed the muffler - top end rpm was
again up around 6800 rpm.
Ed
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Tracy
Crook
Sent: Tuesday, February
09, 2010 8:21 AM
To:
Rotary motors in
aircraft
Subject: [FlyRotary] Re: rpm vs Power was
: Throttle limits was Re: N.A. Renesis to
turbo
Ed's experience pretty
much matches my own when changing gear drive ratios. A little more top
end. (Sun 100 results were 209 mph w/ 2.176 drive vs 217.5 mph the next
year with 2.85 drive.) Takeoff & climb performance improved
dramatically though. It's not an inexpensive change though.
What
does mystify me is the small difference between Mike's static & top end
rpm. I got an 1100 rpm difference. 5200 vs 6300 with a 68 - 81
Performance prop.
Another detail I'm not certain about is whether
Mike's manifold pressure is or is not increasing during that last 1/3 - 1/2
throttle travel with no power increase. Seems like he said it did go up
but I'm not sure. If it is going up, there is still something
unexplained going on. What was the MP doing Mike? Was it at full
ambient at the point where the rpm stopped increasing?
Tracy
On Tue, Feb 9, 2010 at 12:12 AM, Ed Anderson <eanderson@carolina.rr.com>
wrote:
Well, Mike, just for comparison, when I had a 2.17:1
and a 68 x72
Performance prop, 5200 -5400 rpm on a nominal 70deg day was
what I got for
static.
While I don't claim my set up was the best in
the land, I think it was a
pretty fair set up. So I would say you are
doing just fine.
It does not matter how large a throttle body you have
when the manifold air
density hits ambient or as close as it can given any
losses in the induction
system - that's it. You can continue to open
the throttle body, but you
will not get any more power. However, there is a
way!
Looking at some of the variables in the power equation we
have:
Power(HP) = Torque * rpm/ 5250, swapping some variables around we
get:
RPM = Power/torque. So this indicates the rpm can increase
if either the
power is increased or the torque is decreased. Well, it's
difficult to
increase the power by itself(unless you go to forced induction
or nitrous
oxide)
But one way to get more rpm (and ultimately more
power) is to lower the
Torque load on the engine. Decreasing
the Torque permits more engine rpm
even if power did not increase.
However we know that more rpm = more air =
more power. The torque
load on the engine caused by the prop decreases as
your gear ratio
increases.
By going to a 2.85:1 gear ratio that would reduce the
load on the engine by
approx 25% (assuming the same prop at the same static
rpm). Now the rpm
power relationship were linear (which it is not
with a prop as the load)
then I should have gotten around 6650 rpm with the
new gear box - well not
really - due to the cube root relationship between
prop rpm and power, it
will be much less of an increase and due to the fact
I put on a larger
diameter prop.
But in any case, all this theory
aside, with the 2.85 and 74 x88 prop I now
get engine 6000 - 6200 rpm
static or about an 13% increase in rpm. So
that's using use the same
intake, throttle body and engine for both. But
now because the engine
can turn faster (lesser prop load at any specific
rpm).
Now the fact
the engine is turning faster means it takes more airflow to
maintain the
same (ambient) air density in the manifold. This is because the
higher
engine rpm can "suck" that manifold volume (which didn't change)
down
faster than it did before. This in turn means that the throttle
position
has to be more open to let a sufficient increase in air flow need
to achieve
and maintain that (hopefully) ambient air density in the
manifold.
So from what you are reporting, I really don't see anything
poor about your
performance with your set up. In fact, it's pretty
good.
The new set up gave a noticeable benefit in take off performance
(and I do
mean noticeable). However, the top end was relatively
unaffected - although
I did measure an approx 4 mph increase in top
aircraft speed.
In any case, that is my
experience.
FWIW
Ed Anderson
Rv-6A N494BW Rotary
Powered
Matthews, NC
eanderson@carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
-----Original
Message-----
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net]
On
Behalf Of Mike Wills
Sent: Monday, February 08, 2010 10:36 PM
To:
Rotary motors in
aircraft
Subject: [FlyRotary] Re: Throttle limits was Re:
N.A. Renesis to turbo
Thanks Ed. Mentioned this a few months ago and
was convinced at least for
the moment, to just fly the plane as is. So
that's what I have been doing.
To recap, my engine is an NA 13B built
by Bruce Turrentine. It is a
second
gen engine with Turbo rotor housings (no exhaust splitter) and
high
compression NA rotors. The exhaust uses 1 3/4" x 32" primaries into a
Burns
merge collector, 2 1/2" outlet directly into my "muffler". My
"muffler" is
essentially a 4 1/2" x 30" tube with some spiral baffles and 2
1/2"
inlet/outlet. The intake uses a modified 87 lower manifold casting
port
matched to the engine. The upper manifold uses 4 tubes (1 1/2" and 1
1/4"
dia) over the top of the engine to a small dynamic chamber/plenum
directly
over the oil filler port in the center iron housing. The throttle
body
copies Tracy's original - a
stock second gen 3 throat TB cut down to just 2
ports.
The gearbox
is Tracy's first RD-1
with 2.17 gears. Prop is a Warnke 68 x 80
(not sure the pitch number is
meaningful - everyone seems to measure it
differently). On the ground
static RPM is about 5350 and is reached at about
2/3 throttle opening.
In flight max RPM I've seen is about 5750.
The Warnke prop is unique
due to the shape. The appearance gets a lot of
comments. I'm really
hesitant to mess with it and screw it up unless/until I
can say with
certainty that there isnt something else I can do with tweaking
(I'm
thinking on the intake side) to improve airflow through the
engine.
Hard to believe that there isnt more HP to be had when a hacked
2 barrel TB
is only 2/3 open and I've hit the limit. But like you say there
are a lot
of
variables.
Mike
--------------------------------------------------
From:
"Ed Anderson" <eanderson@carolina.rr.com>
Sent:
Monday, February 08, 2010 5:06 AM
To: "Rotary
motors in aircraft" <flyrotary@lancaironline.net>
Subject:
[FlyRotary] Throttle limits was Re: N.A. Renesis to turbo
> Hi
Mike,
>
> Several things could be causing the situation you see in
advancing your
> throttle but getting no increased engine rpm.
This is not an uncommon
> situation. Ok assuming we are talking
naturally aspired engine (no forced
> induction), fixed pitch prop and
assuming your engine is basically OK (not
> weak on compression,
etc),
>
> then the most likely cause is you have simply
reach the point at which
> where the engine is producing all the power
it can - given the prop load
> it
> sees at that moment.
Once that point is reached, then advancing the
> throttle more
does not result in more air flow through the engine and
> therefore no
increase in power nor rpm. In fact, it can cause the engine
>
to
> run leaner and actually produce less power than a partial closed
throttle.
>
> It's sort of the chicken and the egg in that you
need more power to
> produce
> more rpm, but power is dependent on
air flow - which is dependent on rpm
> which dependent on power
produced, etc. {:>). But to try to be a bit more
> helpful,
look at it this way.
>
>
> Basically for every throttle
position (at a constant altitude, temp, air
> density, etc) there is one
associated manifold pressure(air density).
> This
> manifold
pressure is a product of a number of variables, but the most
>
dominating ones involving the engine are volumetric efficiency,
throttle
> position and engine rpm. Now your volumetric
efficiency is more or less
> fixed by the intake/exhaust design so we'll
eliminate that for the moment.
> That leaves throttle position and rpm
as controllable variables and your
> ambient air density as a fixed (for
this discussion).
>
>
> We know the engine is a positive
displacement pump which displaces the
> same
> volume once each
engine cycle. The power the engine produces in that cycle
> is limited
by the density of the air in the combustion chamber as the
>
volume
> is always a constant (fixed by size of your combustion
chamber). The air
> density into the combustion chamber is
dependent on the air density in the
> intake manifold.
>
>
So that leaves us with: More throttle = higher manifold air density
=
> = more oxygen + More fuel(permits more fuel to be burnt) =
more power =
> more rpm. That is until you hit the limit - what
limit you say?
>
> The limit is that once you have opened the
throttle plate sufficiently
> that
> the air density in the intake
manifold is equal to ambient air density (or
> as close as its going to
get- given intake losses) - then it will not make
> any difference (in
power) to advance the throttle further. Once you have
> reached
that limit, then advancing the throttle further does not further
>
increase the air density in the manifold and therefore limits the
amount
> of
> fuel you can burn/power you can
make.
>
> Clearly if you have a large throttle body you can reach
that point with a
> smaller opening of the throttle plate than if you
have a small throttle
> body.
>
> As I said - there can be
other causes, but this is the one I think most
> folks run into. You can
find the same situation even on the ground, where
> again once the
manifold air density = ambient air density (or as close as
> your engine
Ve will permit) you stop producing power increase even if you
> have
throttle travel left.
>
> Therefore if your throttle body is sized
so you get max power at 100%
> throttle opening a sea level, then with
every increase in altitude, you
> will
> find you have additional
throttle travel that produces no increase in
> power.
> The higher
you go in altitude the more throttle travel will be available
> that
results in no power increase. This is because the ultimate limit
is
> based on the ambient air density.
>
> Hope this
helped.
>
> Ed
>
>
>
>
> Ed
Anderson
>
> Rv-6A N494BW Rotary Powered
>
> Matthews,
NC
>
> eanderson@carolina.rr.com
>
>
http://www.andersonee.com
>
> http://www.dmack.net/mazda/index.html
>
> http://www.flyrotary.com/
>
> http://members.cox.net/rogersda/rotary/configs.htm#N494BW
>
>
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
>
>
-----Original Message-----
> From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net]
On
> Behalf Of Mike Wills
> Sent: Sunday, February 07, 2010 12:51
PM
> To: Rotary motors in
aircraft
> Subject: [FlyRotary] Re: N.A. Renesis to
turbo
>
> Don,
>
> I'm at about 23 hours and am seeing
roughly the same performance on my
> RV-4
> with a Bruce T built
gen 2 13B. My temps are a little cooler. I'm pretty
> happy with the
performance, but like you say, its not possible to have too
> much
power. But I don't have room for a turbo and intercooler.
>
> I
think there's more power in my NA engine. I'm still a little mystified
>
by
> the fact that at about 1/2 - 2/3 throttle the engine stops making
any more
> power. But I decided to take several people's advice and just
fly it for a
> while. I also think there's more speed in it via some
drag reduction. A
> turbo would be nice to tame the noise
though.
>
> I'll be interested in seeing how the Burns muffler
works out for you. I'm
> not willing to dive into any more muffler
experiments for the moment since
> my failed trial with the DNA muffler.
But sooner or later, and one way or
> another I have to quiet this thing
down.
>
> Mike Wills
> RV-4 N144MW
>
>
--------------------------------------------------
> From: "Don Wallker"
<drwalker@gbis.com>
> Sent:
Saturday, February 06, 2010 6:21 PM
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
>
Subject: [FlyRotary] N.A. Renesis to turbo
>
>> Dear list,
Turbo flyers and especially David
Leonard,
>> I've 16 flying hours on my
RV-8 with a Renesis and all of Tracy's
>>
stuff
>
>> and a Catto 76/88. The airplane flys great,
just like an RV, no gliding
>> time, and about 36 hours on the
ground. SPECS
>> Full throttle 8,000' 174 mph indicated, 2450
on the prop, water 185,
>> oil
>
>> 205,
>>
Climb out 110 mph, rate of climb, 1250'/min. Field elevation
5046.
>>
>> These are not bad numbers, but I would like
better. I've been influenced
>> by some of the the local jet
jocks who say that there is no such thing as
>> too much horsepower
and they are right! N113BR seems to be performing
>> about
like a 160-170 HP RV. So I am investigating turboing it! The
idea
>> is to have a little better than sea level performance on take
off
>> (designed for 210HP N.A.) and turbo normalizing at cruise.
Up to 12000'
>> would be nice.
>> During the air races
this year, Dave Leonard showed up
and I was very
>> impressed by his airplane. He was able to
turbo and inter cool it and
>> have it all inside an RV cowl, so I'll
likely base my installation on
>> his. Plus, he has been
through the learning curve of 3 or so turbos so
>>
he
>
>> knows what to do, what not to do and what would be
better if he were to
>> do
>
>> it all over
again.
>>
>> I've spent the afternoon looking through the
archives, reading as much as
>> I can find about turbos, and
downloading all the photos I can. Here is
>> what I am
tentatively planning on doing.
>> Get one of Techwelding's
Renesis exhaust flanges made from 304 SS and
>>
have
>
>> my local waterjet guy copy it and make one out of
321SS. I'll weld 321
>> SS
>
>> and
manifold it together and run it into the bottom of the turbo
that
>> will sit right in front of the exhaust. The turbo will
have additional
>> support. Run the turbo outlet air from it
through a stock RX-7 inter
>> cooler sitting in front of the left
cheek opening and then out to the
>> right side of the engine,
probably routing it under the PSRU and then up
>> to a throttle body
and manifold. Then four al tubes over the top of the
>> engine
into a cut down and welded up stock RX-8 intake manifold.
The
>> exhaust out of the turbo will run down and out in the
usual center of the
>> back of the cowl opening. I am thinking
of trying one of Burns Stainless
>> all SS mufflers. It is
basically a glass pack, but instead of glass,
>>
they
>
>> are using stainless steel wool and they say it is
holding up for the
>> rotary racers. They make it any length
you want and is about 4 lbs with
>> their SS vs 9 lbs with the
hushpower 2 I'm using now. The combustion air
>> intake to the
turbo will be on the aft left side of the cowl via an NACA
>> duct
opening as Dave's is.
>> The oil cooler will have to be moved to
under the engine. I will build
>> up
>
>> a
fiberglass scoop, probably based on Van's scoop and modify it to have
a
>> bigger opening and be farther forward, closer to the prop.
I will
>> probably have the oil cooler made a little
larger (Techwelding) than the
>> one I have
now.
>>
>> That's the basic idea at this point. I'll
finalize my plan, prebuild as
>> much as possible before tearing the
airplane apart and try for as little
>> down time as possible.
I'm looking for the list's critique here, plus
>> questions
that I will have missed. The following are a list of
questions
>> that I have.
>> 1. Which turbo should I use,
which orientation and who should I use to do
>> the work, plus what
is the approximate price? TO4 hybrid? Dave and
>> Steve
Brooks mention BNR turbo as a modifier. Who manufactures the
>>
turbo?
>> 2. What is the ideal situation with a waste gate?
Full open or not, or,
>> or?
>> 3. I read about a
N.O.oil line solenoid to the turbo bearings. I assume
>> that
if the Turbo fails, you turn it on to the N.C. position to prevent
>>
oil from being pumped down your exhaust? I assume the oil that is
used
>> is
>
>> routed back to the sump.
>>
4. What size exhaust is optimum? It seems Dave is running 2.5
inch.
>> 5. What size throttle body should I use and what would
be a good one?
>> One
>
>> throttle body or two? 4.
What size injectors should I use, and where
>> should the
secondaries be placed? Dave is using 480cc and staging is
at
>> 32 inches. Are you using the same for the primaries and
is there an idle
>> problem with the larger injectors?
>> 5.
Anyone out there turboing a Renesis? Anyone flying
one?
>> 6. My compression is 9.7 to 1. Any problems with
this higher
>> compression ratio as long as I use an inter cooler and
keep the boost no
>> higher than 35"?
>> And lot more
questions, but that's all I can think of now.
>> So If any of you can
add any thought, let me know.
>>
>> Don
Walker
>>
>> --
>> Homepage: http://www.flyrotary.com/
>> Archive and
UnSub:
>> http://mail.lancaironline.net:81/lists/flyrotary/List.html
>>
>
>
>
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