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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
>>
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>> Homepage: http://www.flyrotary.com/
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