Author: David Talley <dtalley1@...> Time: Thu Aug 26, 2004 4:30 pm PDT Link
The folks at Innodyn were claiming 6 to 7 GPH per 100 HP at OSH.
When I asked for EXACT fuel burn rates they said they were working on
it. When I pressed for the TRUTH (You know airshow sales reps) they think
it will probably be closer to the 5 GPH per 100 HP. At least in the 5
point something range. Of course, no guarantees!
They have two patents on the fuel system. The digital system makes
corrections to the fuel burn every 20 degrees of rotation of the turbine wheel.
Now let's look at that: The turbine turns about 60,000 RPM (Actually around
61,000 but the math is easier with 60k).
The turbine is spinning at 1000 RPS (That's on thousand times per
SECOND!) The computer is making corrections every 20 degrees of
rotation. 360 divided by 20 equals 18. That's a computer adjustment
eighteen times per rotation. 1000 times 18 is 18,000 times a SECOND
adjustments are made. Multiply that by 60 and well you get the message.
So in the old days it was done mechanically, today the digital computer
does the trick. We all remember growing up thinking of a turbine for some
kind of homebuilt. However, the fuel consumption was so high, it wasn't
worth the effort. Things have definitely changed!
Remember, the only CONSTANT is CHANGE itself! Sometimes technology is a
good thing!
Innodyn and Rivers just got the RV-6AT flying with the NSI prop. The RV-4
has an MT three blade prop. I think the correct prop will be the biggest
factor in the FLYING numbers. NSI had a sheet listing a prop for the "ATP"
at OSH. I'm looking forward to the numbers. I think that other prop
players in the world might have stopped by to look at the engine. Time
will tell. A lot of you are way ahead in the building process then my
lovely bride and me. I, too, want some more definitive numbers, but am
willing to wait. Just how long is another issue.
Dave Talley
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Author: "eric_panning" <eric_panning@...> Time: Thu Aug 26, 2004 6:23 pm PDT Link
Dave,
We have similar views on technology but I disagree on this topic.
Disagreement is ok and if you will share the skies with me I will
share them with you.
I'm not sure I follow all your comments on computer control of fuel
delivery. Do you know what they are monitoring at 18 kHz? Temp
or ???? I agree that computer control might help at idle power to
minimize fuel burn (not a strong point for turbines) I'm not sure
how the control helps at cruise settings. 5 gal per 100 HP is a BSFC
of ~ 0.35. Based on thermodynamics, I think this is unreasonably low
for practical exhaust turbine temps.
Do you know why they have moved away from MT props? It would be
interesting to see the article written in sport aviation where the
speed was at ~ 160 mph?. Why don't they link that article on their
site?
Generally speaking, I would not expect a big improvement from a new
prop for long winded reasons. :) I think that is part of the reason
why people are wondering why they have not released performance data.
If you go to the internet archive (Wayback machine) for ~ 2001 you
will find the following data for www.atpoinc.com (pre- Innodyn)
ATP Model 6.5
HP Static Thrust RPM GPH [BSFC]
120 300 lbs 2650 10.7 0.62
150 375 lbs 2650 11.6 0.54
180 450 lbs 2750 13.4 0.52
210 525 lbs 3000 14.9 0.50
240 600 lbs 3050 16.6 0.48
To my knowledge, this was the only data openly posted and I have
watched their site since ~ 2001. I'm not sure if it is actual or
model data. The above numbers were with computer controlled ignition
and are consistent with what would be typical of turbines. I have
added the [BSFC] numbers. If this is the engine they installed in the
RV-4 then they should have seen 212 mph at gross weight with 180 HP
and a typical prop. Looking at Van's numbers online, an RV-4 flying
at only 160 mph would take less than 82 HP. (An RV-10, being bigger
and heavier requires ~ 115 HP for the same speed)
I would rec. raising these concerns directly with Innodyn. If I have
stated something incorrectly I am more than willing to retract it.
http://web.archive.org/web/19960101000000-
20031231235959/http://atpcoinc.com/Pages/Products.html
Eric
RV10 kit 40150
--- In RV10@yahoogroups.com, David Talley <dtalley1@s...> wrote:
> The folks at Innodyn were claiming 6 to 7 GPH per 100 HP at OSH.
>
> When I asked for EXACT fuel burn rates they said they were working
on
> it. When I pressed for the TRUTH (You know airshow sales reps)
they think
> it will probably be closer to the 5 GPH per 100 HP. At least in
the 5
> point something range. Of course, no guarantees!
>
> They have two patents on the fuel system. The digital system makes
> corrections to the fuel burn every 20 degrees of rotation of the
turbine wheel.
>
> Now let's look at that: The turbine turns about 60,000 RPM
(Actually around
> 61,000 but the math is easier with 60k).
>
> The turbine is spinning at 1000 RPS (That's on thousand times per
> SECOND!) The computer is making corrections every 20 degrees of
> rotation. 360 divided by 20 equals 18. That's a computer
adjustment
> eighteen times per rotation. 1000 times 18 is 18,000 times a
SECOND
> adjustments are made. Multiply that by 60 and well you get the
message.
>
> So in the old days it was done mechanically, today the digital
computer
> does the trick. We all remember growing up thinking of a turbine
for some
> kind of homebuilt. However, the fuel consumption was so high, it
wasn't
> worth the effort. Things have definitely changed!
>
> Remember, the only CONSTANT is CHANGE itself! Sometimes technology
is a
> good thing!
>
> Innodyn and Rivers just got the RV-6AT flying with the NSI prop.
The RV-4
> has an MT three blade prop. I think the correct prop will be the
biggest
> factor in the FLYING numbers. NSI had a sheet listing a prop for
the "ATP"
> at OSH. I'm looking forward to the numbers. I think that other
prop
> players in the world might have stopped by to look at the engine.
Time
> will tell. A lot of you are way ahead in the building process then
my
> lovely bride and me. I, too, want some more definitive numbers,
but am
> willing to wait. Just how long is another issue.
>
> Dave Talley
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Author: "Chris , Susie McGough" <VHMUM@...> Time: Fri Aug 27, 2004 3:40 am PDT Link
Eric good points ....I only work on what I see and experience. . Harmon (who builds all RV gear legs) got rid of the MT prop because it was waaay to slooooow. He Put a Hartzel on and yippee!!
Chris
----- Original Message -----
From: eric_panning
To: RV10@yahoogroups.com
Sent: Friday, August 27, 2004 11:03 AM
Subject: [RV10] Re: Fuel burn-Innodyn turbines
Dave,
We have similar views on technology but I disagree on this topic.
Disagreement is ok and if you will share the skies with me I will
share them with you.
I'm not sure I follow all your comments on computer control of fuel
delivery. Do you know what they are monitoring at 18 kHz? Temp
or ???? I agree that computer control might help at idle power to
minimize fuel burn (not a strong point for turbines) I'm not sure
how the control helps at cruise settings. 5 gal per 100 HP is a BSFC
of ~ 0.35. Based on thermodynamics, I think this is unreasonably low
for practical exhaust turbine temps.
Do you know why they have moved away from MT props? It would be
interesting to see the article written in sport aviation where the
speed was at ~ 160 mph?. Why don't they link that article on their
site?
Generally speaking, I would not expect a big improvement from a new
prop for long winded reasons. :) I think that is part of the reason
why people are wondering why they have not released performance data.
If you go to the internet archive (Wayback machine) for ~ 2001 you
will find the following data for www.atpoinc.com (pre- Innodyn)
ATP Model 6.5
HP Static Thrust RPM GPH [BSFC]
120 300 lbs 2650 10.7 0.62
150 375 lbs 2650 11.6 0.54
180 450 lbs 2750 13.4 0.52
210 525 lbs 3000 14.9 0.50
240 600 lbs 3050 16.6 0.48
To my knowledge, this was the only data openly posted and I have
watched their site since ~ 2001. I'm not sure if it is actual or
model data. The above numbers were with computer controlled ignition
and are consistent with what would be typical of turbines. I have
added the [BSFC] numbers. If this is the engine they installed in the
RV-4 then they should have seen 212 mph at gross weight with 180 HP
and a typical prop. Looking at Van's numbers online, an RV-4 flying
at only 160 mph would take less than 82 HP. (An RV-10, being bigger
and heavier requires ~ 115 HP for the same speed)
I would rec. raising these concerns directly with Innodyn. If I have
stated something incorrectly I am more than willing to retract it.
http://web.archive.org/web/19960101000000-
20031231235959/http://atpcoinc.com/Pages/Products.html
Eric
RV10 kit 40150
--- In RV10@yahoogroups.com, David Talley <dtalley1@s...> wrote:
> The folks at Innodyn were claiming 6 to 7 GPH per 100 HP at OSH.
>
> When I asked for EXACT fuel burn rates they said they were working
on
> it. When I pressed for the TRUTH (You know airshow sales reps)
they think
> it will probably be closer to the 5 GPH per 100 HP. At least in
the 5
> point something range. Of course, no guarantees!
>
> They have two patents on the fuel system. The digital system makes
> corrections to the fuel burn every 20 degrees of rotation of the
turbine wheel.
>
> Now let's look at that: The turbine turns about 60,000 RPM
(Actually around
> 61,000 but the math is easier with 60k).
>
> The turbine is spinning at 1000 RPS (That's on thousand times per
> SECOND!) The computer is making corrections every 20 degrees of
> rotation. 360 divided by 20 equals 18. That's a computer
adjustment
> eighteen times per rotation. 1000 times 18 is 18,000 times a
SECOND
> adjustments are made. Multiply that by 60 and well you get the
message.
>
> So in the old days it was done mechanically, today the digital
computer
> does the trick. We all remember growing up thinking of a turbine
for some
> kind of homebuilt. However, the fuel consumption was so high, it
wasn't
> worth the effort. Things have definitely changed!
>
> Remember, the only CONSTANT is CHANGE itself! Sometimes technology
is a
> good thing!
>
> Innodyn and Rivers just got the RV-6AT flying with the NSI prop.
The RV-4
> has an MT three blade prop. I think the correct prop will be the
biggest
> factor in the FLYING numbers. NSI had a sheet listing a prop for
the "ATP"
> at OSH. I'm looking forward to the numbers. I think that other
prop
> players in the world might have stopped by to look at the engine.
Time
> will tell. A lot of you are way ahead in the building process then
my
> lovely bride and me. I, too, want some more definitive numbers,
but am
> willing to wait. Just how long is another issue.
>
> Dave Talley
Yahoo! Groups Sponsor
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Author: lessdragprod@... Time: Fri Aug 27, 2004 3:41 am PDT Link
Hi All,
The previously provided chart copied below shows exactly why Innodyn has
gone away from the MT Propeller. 2800 RPM looks like about 186 hp.
2800 RPM is the maximum allowable RPM for the MT Propeller.
I talked with one of the Innodyn people about using a different gear ratio
so the propeller RPM would run at around 2000 RPM. I believe they said they
had a gear reduction unit available for 2000 propeller RPM, but at least ten
people would have to buy the engine package before it would be available.
Somehow getting aircraft performance be using an optimum propeller RPM was not
an obvious concept.
With regard to turbine design, I had to dust off a few cobwebs.
For single stage turbines, 0.75 pounds per shaft horsepower hour was a
maximum fuel efficiency. 1.0 pounds per shaft horsepower hour was more typical.
I also seem to recall that 60% fuel flow was required just to run with zero
power output. So partial power flight wouldn't seem practical. (50%
propeller thrust would be at around 80% fuel flow.)
The best fuel efficiency I've ever seen documented was on a turbofan engine.
It was running at 0.398 pounds per pound thrust per hour. Perhaps the
newer 100,000+ pound thrust turbofan engines are even more efficient.
IMHO, if someone says they are running a small turbine engine at 0.35 pounds
per shaft horsepower per hour, then they are not using Jet A. It seems more
likely that it is running on snake oil. :-)
Jim Ayers
In a message dated 08/26/2004 6:49:15 PM Pacific Daylight Time,
eric_panning@yahoo.com writes:
(Stuff Cut)
Do you know why they have moved away from MT props? It would be
interesting to see the article written in sport aviation where the
speed was at ~ 160 mph?. Why don't they link that article on their
site?
Generally speaking, I would not expect a big improvement from a new
prop for long winded reasons. :) I think that is part of the reason
why people are wondering why they have not released performance data.
If you go to the internet archive (Wayback machine) for ~ 2001 you
will find the following data for www.atpoinc.com (pre- Innodyn)
ATP Model 6.5
HP Static Thrust RPM GPH [BSFC]
120 300 lbs 2650 10.7 0.62
150 375 lbs 2650 11.6 0.54
180 450 lbs 2750 13.4 0.52
210 525 lbs 3000 14.9 0.50
240 600 lbs 3050 16.6 0.48
(Stuff Cut)
[Non-text portions of this message have been removed]
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Author: robhickman@... Time: Fri Aug 27, 2004 3:13 pm PDT Link
In a message dated 8/27/2004 3:59:47 AM Pacific Daylight Time,
VHMUM@bigpond.com writes:
Harmon (who builds all RV gear legs) got rid of the MT prop because it was
waaay to slooooow. He Put a Hartzel on and yippee!!
Actually he put on the new Whirl Wind 200RV
Rob Hickman
RV-4 N401RH
RV-10 N402RH
[Non-text portions of this message have been removed]
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Author: "Martin Gomez" <mlg28@...> Time: Tue Aug 31, 2004 2:37 pm PDT Link
As I recall, that article in Sport Aviation SAYS why they had RESTRICT the speed to 160
mph. Didn't they say something like this:
... because their exhaust stack was flush with the fuselage, i.e. parallel to the airflow, so
when the air blew by, it created backpresure, which caused high TIT. They couldn't push
the power level all the way to the max because they'd exceed the TIT limit, so they got 160
mph worth of power. They even said "now we know why King Airs and the like have the
exhaust stack bent aft."
I still have high hopes for these folks.
Martin
--- In RV10@yahoogroups.com, "eric_panning" <eric_panning@y...> wrote:
> Do you know why they have moved away from MT props? It would be
> interesting to see the article written in sport aviation where the
> speed was at ~ 160 mph?.
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Author: Scott Bilinski <bilinski@...> Time: Tue Aug 31, 2004 3:49 pm PDT Link
I honestly have high hopes too, but just like people I dont care what they
say I care about what they do. So far they are not doing a whole lot except
talking. They have had over 2 years to fix that exhaust problem and at OSH
I noticed the exhaust was the same as the last time I saw it 2 years ago,
at OSH. I also posted on their E-mail list about the intake and exhaust,
is, the way it is, on production planes for a reason.......because it
works!!! They told me they are breaking new ground and not following the
old ideas. They have had plenty of time to fix it. Hmmmm, now that I think
about it, I have not got an E-mail from their list in over a month
now......I guess they dont like my questions and removed me?
At 08:19 PM 8/31/2004 +0000, you wrote:
>As I recall, that article in Sport Aviation SAYS why they had RESTRICT the
>speed to 160
>mph. Didn't they say something like this:
>
>.... because their exhaust stack was flush with the fuselage, i.e.
>parallel to the airflow, so
>when the air blew by, it created backpresure, which caused high TIT. They
>couldn't push
>the power level all the way to the max because they'd exceed the TIT
>limit, so they got 160
>mph worth of power. They even said "now we know why King Airs and the
>like have the
>exhaust stack bent aft."
>
>I still have high hopes for these folks.
>
>Martin
>
>--- In RV10@yahoogroups.com, "eric_panning" <eric_panning@y...> wrote:
> > Do you know why they have moved away from MT props? It would be
> > interesting to see the article written in sport aviation where the
> > speed was at ~ 160 mph?.
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