Today's Message Index:
----------------------
1. 05:42 AM - Re: Alternate Engines (James R. Cunningham)
2. 07:21 AM - Re: Alternate Engines (Healy, Joseph)
3. 07:36 AM - Turbine engines (Gary Casey)
4. 08:03 AM - Renesis Rotary (Scott)
5. 08:14 AM - Re: Turbine engines (Healy, Joseph)
6. 10:28 AM - Re: RX8 HP??? (Nielsenbe@aol.com)
7. 12:14 PM - Re: Alternate Engines (Fergus Kyle)
8. 03:03 PM - Re: Alternate Engines (Tracy Crook)
9. 03:12 PM - Re: Renesis Rotary (Tracy Crook)
10. 03:30 PM - Re: RX8 HP??? (Tracy Crook)
Message 1
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| Subject: | Re: Alternate Engines |
--> Engines-List message posted by: "James R. Cunningham" <jrccea@bellsouth.net>
Do a google searh for
+"o-234" +"o-290" +bore +stroke
One of the hits is a table of differences between all Lycoming engines.
sportpilot wrote:
>
> --> Engines-List message posted by: "sportpilot" <sportpilot@moneypit.com>
>
> what is the difference between a 0235 lycoming and a 290 ? any info would
> help alot..
Message 2
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| Subject: | Alternate Engines |
--> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
Tracy,
I know you're a rotary guru, but I disagree that adding a PRT would
never pay for itself. Documentation I have dug up so far on the R3350
indicates an overall 20% increase in that engine's performance due to
the PRT with no heat or fuel penalty. The Constellation was the
pinnacle of long haul piston technology. Were it not for jet engine and
turbo prop development (and product liability issues that stunted GA
development) I suspect you would see more PRT's in aircraft today.
But that is my reason for pursuing this issue. I don't see too many
viable jet or turbo prop options for my 100hp Vari EZ. Plus there seems
to be insurance issues with gas turbines. So, a 20% increase in
performance, be it in range or power (without too much bleeding edge
technology) sounds good to me. Combined with a rotary engine, that might
be a winning combination.
The fact that the new RX-8 rotary is as efficient as a piston engine is
may be good news (after all 5% is 5%). But, possibly that is a step in
the wrong direction for a rotary/PRT combination. I was hoping for some
theoretical technical input from a turbo machinery designer, that would
compliment the valuable opinions heard so far.
I read that the Constellation R3350 engine with PRT was a maintenance
problem because when the piston engine lost a valve it wrecked the PRT.
With a rotary, the PRT would be immune to such a failure. What other
issues contributed to the Connie's PRT maintenance "nightmare"?
Joe
The "much worse" on the rotary engine is greatly exaggerated. It
amounts to perhaps 5% difference. The exhaust turbine recovery is an
old idea which was used on the old 3340 (?) radials used on the
Constellations (Connie). They were a maintenance nightmare then and I
suspect they would be now. In practical terms, it would never pay for
itself even though it does offer some increase in efficiency. The 5%
disadvantage is now gone on the new Renesis rotary engine used in the
RX-8. Exhaust temp is now same as on piston engines. Was 150 - 200 F
higher on the 1971 - 1997 rotary engines. Tracy Crook
Message 3
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--> Engines-List message posted by: "Gary Casey" <glcasey@adelphia.net>
<<Anyway, put the two concepts together using a rotary engine. That is,
use the exhaust gasses from the wankel engine to run a turbine that is
connected to a concentric counter rotating propeller shaft. This would
take advantage of the increased prop efficiency of the counter rotating
props and make use of the otherwise wasted exhaust gasses (which are of
course much worse on a rotary engine). Obvious centerline thrust
advantages.
Any thoughts?
Joe, N64CB>>
An interesting idea. There once was a project somewhere in the automotive
companies that used a piston engine (free-piston) as a gas generator for a
turbine. No power at all was extracted from the piston engine. A rotary
could be used for this purpose, run in a highly-boosted state and used as a
supplier of hot exhaust gas under pressure to run a turbine. I doubt,
without doing any calculations, that it would sufficiently efficient, but it
is an interesting thought.
Gary Casey
Message 4
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--> Engines-List message posted by: Scott <scott@tnstaafl.net>
>The 5% disadvantage is now gone on the new Renesis rotary engine used in
>the RX-8. Exhaust temp is now same as on piston engines. Was 150 - 200 F
>higher on the 1971 - 1997 rotary engines.
>Tracy Crook
Tracy,
The new Renesis is looking better and better. Everytime I read something
new about it, I'm impressed.
Do you know if we can buy them from Mazda dealers yet? Prices?
And most important, has anybody got a turbo designed for it yet? I'm not
that interested in raising the HP output as I am in Turbo-Normalizing it up
to 18,000 ft. Also a turbo could be used to pressurize the airplane, an
item near the top of my "next plane" list.
Scott
Message 5
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--> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
Gary,
I never heard of that. Do you have any more info?
I would expect a couple of problems with a free piston concept. Maybe
that's why it failed. Assuming that one is not designing what amounts
to a piston combustor for a jet engine from scratch. Adapting an
existing positive displacement engine that was originally designed for a
certain delivery shaft hp would waste the power plants capability and
the exhaust gasses would be at a higher temperature.
Volumetric through put for a piston is limited compared with an axial
compressor so you would need a very high RPM to get comparable
performance with a traditional jet combustor design. So maybe a rotary
version at high RPM would be just the ticket. However, the higher
exhaust gas temperature of an unloaded rotary type combustor-only
"thing" might burn the exhaust ports in an automotive conversion.
I would think 75% shaft hp from the engine and 25% from the power
recovery turbine. But that is assuming normal piston RPM's. Maybe one
could run the rotary at a very high RPM and directly connect the PRT to
the crankshaft. But I originally was in favor of not connecting the two
together. Rather, put the turbine on a separate concentric shaft
running a counter rotating prop. Now if these were small diameter high
RPM propellers, in a ducted fan you wouldn't need a geared PRU.
Joe
<
<
<There once was a project somewhere in the automotive companies that
used a piston engine (free-piston) as a gas generator for a turbine. No
power at all was extracted from the piston engine. A rotary could be
used for this purpose, run in a highly-boosted state and used as a
supplier of hot exhaust gas under pressure to run a turbine. I doubt,
without doing any calculations, that it would sufficiently efficient,
but it is an interesting thought.
Message 6
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--> Engines-List message posted by: Nielsenbe@aol.com
what are the HP numbers for a turbo RX8 engine? and about what fuel burn?
Thanks, Brad
Message 7
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| Subject: | Re: Alternate Engines |
--> Engines-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
I think the adding of a recovery turbine in the Wankel exhaust (while an
interesting concept) is a practical nightmare. tracvy is correct that the
R3350 +PRT was a maintenance terror, but not just for exhaust valve stem
failure. The technology of fast rotation was not advanced and the
maintenance and repair of the PRT kept several companies in the black for
the eight years I flew the L1049E to G models. What made it viable then was
a great increase in long-distance travel customers. The Connie reduced the
seatmile costs and we could afford the extra maintenance costs. You can't. I
seem to remember the engineering branch claiming a recovered 300hp from the
3 PRTs per engine.
Also, I don't believe there's enough recovery from the overall
efficiency of the proposal to merit the added complexity. The improved fuel
efficiency ascribed to the Wright PRTs appeared good because it was so poor
earlier. The law of dimishing returns from what are now more fuel efficient
models would tend to diminish the advantages IMHO.
Ferg
Europa A064 mono
----- Original Message -----
From: "Healy, Joseph" <WJH@brplusa.com>
Subject: RE: Engines-List: Alternate Engines
| --> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
|
| Tracy,
|
| I know you're a rotary guru, but I disagree that adding a PRT would
| never pay for itself. Documentation I have dug up so far on the R3350
| indicates an overall 20% increase in that engine's performance due to
| the PRT with no heat or fuel penalty. The Constellation was the
| pinnacle of long haul piston technology. Were it not for jet engine and
| turbo prop development (and product liability issues that stunted GA
| development) I suspect you would see more PRT's in aircraft today.
|
| But that is my reason for pursuing this issue. I don't see too many
| viable jet or turbo prop options for my 100hp Vari EZ. Plus there seems
| to be insurance issues with gas turbines. So, a 20% increase in
| performance, be it in range or power (without too much bleeding edge
| technology) sounds good to me. Combined with a rotary engine, that might
| be a winning combination.
|
| The fact that the new RX-8 rotary is as efficient as a piston engine is
| may be good news (after all 5% is 5%). But, possibly that is a step in
| the wrong direction for a rotary/PRT combination. I was hoping for some
| theoretical technical input from a turbo machinery designer, that would
| compliment the valuable opinions heard so far.
|
| I read that the Constellation R3350 engine with PRT was a maintenance
| problem because when the piston engine lost a valve it wrecked the PRT.
| With a rotary, the PRT would be immune to such a failure. What other
| issues contributed to the Connie's PRT maintenance "nightmare"?
|
| Joe
|
| The "much worse" on the rotary engine is greatly exaggerated. It
| amounts to perhaps 5% difference. The exhaust turbine recovery is an
| old idea which was used on the old 3340 (?) radials used on the
| Constellations (Connie). They were a maintenance nightmare then and I
| suspect they would be now. In practical terms, it would never pay for
| itself even though it does offer some increase in efficiency. The 5%
| disadvantage is now gone on the new Renesis rotary engine used in the
| RX-8. Exhaust temp is now same as on piston engines. Was 150 - 200 F
| higher on the 1971 - 1997 rotary engines. Tracy Crook
|
|
|
|
|
|
|
Message 8
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| Subject: | Re: Alternate Engines |
--> Engines-List message posted by: "Tracy Crook" <lors01@msn.com>
I agree with you on the efficiencies to be had with PRT technology. It's the development
costs (and size) that would kill it. This thing has the same problem
as the turbine engine. Efficiencies are much better when they are scaled
up in size, which is one reason it worked reasonably well on the R3350. Note
the two huge engines on the Boeing 777. Also note the failure of the tiny engines
which were supposed to go on the Eclipse jet. Small is very hard to do.
If you have an extra $20,000,000 to develop this thing for the 100 - 200 HP engine
market , it would definitely work. But I think you would also go broke.
Tracy
--> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
Tracy,
I know you're a rotary guru, but I disagree that adding a PRT would
never pay for itself. Documentation I have dug up so far on the R3350
indicates an overall 20% increase in that engine's performance due to
the PRT with no heat or fuel penalty. The Constellation was the
pinnacle of long haul piston technology. Were it not for jet engine and
turbo prop development (and product liability issues that stunted GA
development) I suspect you would see more PRT's in aircraft today.
But that is my reason for pursuing this issue. I don't see too many
viable jet or turbo prop options for my 100hp Vari EZ. Plus there seems
to be insurance issues with gas turbines. So, a 20% increase in
performance, be it in range or power (without too much bleeding edge
technology) sounds good to me. Combined with a rotary engine, that might
be a winning combination.
The fact that the new RX-8 rotary is as efficient as a piston engine is
may be good news (after all 5% is 5%). But, possibly that is a step in
the wrong direction for a rotary/PRT combination. I was hoping for some
theoretical technical input from a turbo machinery designer, that would
compliment the valuable opinions heard so far.
I read that the Constellation R3350 engine with PRT was a maintenance
problem because when the piston engine lost a valve it wrecked the PRT.
With a rotary, the PRT would be immune to such a failure. What other
issues contributed to the Connie's PRT maintenance "nightmare"?
Joe
The "much worse" on the rotary engine is greatly exaggerated. It
amounts to perhaps 5% difference. The exhaust turbine recovery is an
old idea which was used on the old 3340 (?) radials used on the
Constellations (Connie). They were a maintenance nightmare then and I
suspect they would be now. In practical terms, it would never pay for
itself even though it does offer some increase in efficiency. The 5%
disadvantage is now gone on the new Renesis rotary engine used in the
RX-8. Exhaust temp is now same as on piston engines. Was 150 - 200 F
higher on the 1971 - 1997 rotary engines. Tracy Crook
Message 9
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| Subject: | Re: Renesis Rotary |
--> Engines-List message posted by: "Tracy Crook" <lors01@msn.com>
--> Engines-List message posted by: Scott scott@tnstaafl.net
>The 5% disadvantage is now gone on the new Renesis rotary engine used in
>the RX-8. Exhaust temp is now same as on piston engines. Was 150 - 200 F
>higher on the 1971 - 1997 rotary engines.
>Tracy Crook
Tracy,
The new Renesis is looking better and better. Everytime I read something
new about it, I'm impressed.
Do you know if we can buy them from Mazda dealers yet? Prices?
And most important, has anybody got a turbo designed for it yet? I'm not
that interested in raising the HP output as I am in Turbo-Normalizing it up
to 18,000 ft. Also a turbo could be used to pressurize the airplane, an
item near the top of my "next plane" list.
Scott
It will take some time for Mazda to fill the supply line but yes, the engine will
be available. Mechanic's net price is something like $5800. I'm having Bruce
Turrentine build me one from parts now. Engine - Turbo matching appears
to be as much art as science. Lots of turbo work going on for automotive & marine
applications but you have the chance to be first on the aircraft turbo application
of the Renesis.
Tracy
Message 10
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--> Engines-List message posted by: "Tracy Crook" <lors01@msn.com>
----- Original Message -----
From: Nielsenbe@aol.com
Subject: Re: Engines-List: RX8 HP???
--> Engines-List message posted by: Nielsenbe@aol.com
what are the HP numbers for a turbo RX8 engine? and about what fuel burn?
Thanks, Brad
There is no such thing as a turbo RX-8 (yet) but it makes 238 HP normally aspirated
in automotive trim (cat converters, restrictive mufflers, etc) I get a best
of .46 - .47 BSFC at cruise on an 89 vintage 13B. The Renesis will be about
5% better I suspect. The improvement on the car is much better than this.
At idle & low speed the Renesis is %40 better than the earlier rotaries. An
idling rotary (earlier model) is a real hog. This really does not affect us
much in airplanes though.
Tracy
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