Rotary Engines for Helicopter? (eg. Mazda Renesis Engine, RX7)
sanman
I was reading about Wankel rotary engines, including the new improved
Mazda Renesis engine. They seem to provide higher RPMs and more power,
with lower weight and compact size, as well as less vibration. I'd
like to then know why a rotary engine such as the Renesis wouldn't be
nice for a small helicopter type of aircraft?
I'd read that with rotary engines, one big issue is adequate airflow,
but I'd assume that the airflow with an aircraft caters to that issue
quite well.
I'd heard some say that rotary engines aren't quite as good on fuel
economy as a piston engine, but that the new Renesis may have closed
the gap or even taken a lead.
The whole higher RPMs idea seems to cater to the needs of a helicopter
quite well. I'd also wonder how the engine reliability would compare,
such as in avoiding engine stalls, etc.
Is there any information on the net, on how to fit a rotary engine to
a small helicopter or even a gyroplane?
Craig C.
>Is there any information on the net, on how to fit a rotary engine to
>a small helicopter or even a gyroplane?
Haven't seen any, but that doesn't mean that it hasn't been done.
There used to be a pretty active group that converted them for fixed
wing use and had gained a considerable amount of time with them. You
might do some looking in that vein first. There might still be an
e-mail list on those engines too.
I think that there is an experimental helo group out there too, so you
might do a little digging in that direction.
BTW...smallest helo that I know of that might be near rotatry ready is
the RotorMouse. It's designed for a T-62 turbine.
Good luck and have fun...
Craig C.
Jon Williams
www.moller.com use rotary engines (their own design) in their skycar range.
JPW
Rhodesst
>Hi,
>
>I was reading about Wankel rotary engines, including the new improved
>Mazda Renesis engine. They seem to provide higher RPMs and more power,
>with lower weight and compact size, as well as less vibration. I'd
>like to then know why a rotary engine such as the Renesis wouldn't be
>nice for a small helicopter type of aircraft?
>
Hmmm, interesting. I've not hear of this engine. I'll have to look it up!
:-)
>I'd read that with rotary engines, one big issue is adequate airflow,
>but I'd assume that the airflow with an aircraft caters to that issue
>quite well.
>
One would think that airflow wouldn't be a problem in an aircraft but what
about a hovering helicopter?
>I'd heard some say that rotary engines aren't quite as good on fuel
>economy as a piston engine, but that the new Renesis may have closed
>the gap or even taken a lead.
>
The older rotory engines that Mazda put out weren't quite as good on fuel
economy as their piston powered counterparts from what I'd heard. If they've
managed to improve it, that's great.
>The whole higher RPMs idea seems to cater to the needs of a helicopter
>quite well. I'd also wonder how the engine reliability would compare,
>such as in avoiding engine stalls, etc.
>
Higher RPM isn't necessarily the point in a helicopter. What's more important,
I think, is the engines ability to produce usable torque throughout a
relatively wide RPM band. If this new rotory can do that better than it's
piston engine cousins, it should make a good candidate.
>Is there any information on the net, on how to fit a rotary engine to
>a small helicopter or even a gyroplane?
I can't say I've seen a rotory engine in a helicopter but there are several
gyroplanes out in the world that have been powered by converted Mazda engines.
FWIW,
Fly Safe,
Steve
multi...@yahoo.com
Also have a nice 13B rebuild video. I have seen it and recommend it !
Wim.
"sanman" <sanm...@my-deja.com> wrote in message
news:f69a20c6.01060...@posting.google.com...
The Charltons
at Kerrville. He ran it up, hovered for a while, but I can't remember if I
saw him fly away with it or not. Seemed to run fine and wasn't as loud as I
expected it might be.
Duncan
Jesse D. Sightler
Diesel
state they have put em in airplanes and are one of the best motor builders
in the country
sanman
> Hmmm, interesting. I've not hear of this engine. I'll have to look it up!
> :-)
Check out
www.wankel-rotary.com
www.avnet.co.uk/midwestengines/html/helicopters.html
www.stittind.com
www.usbusiness.com/helicopter/WScor1.htm
> One would think that airflow wouldn't be a problem in an aircraft but what
> about a hovering helicopter?
Yeah, I think it's just a matter of decent-sized intakes. It seems to
work fine in a stationary car.
> The older rotory engines that Mazda put out weren't quite as good on fuel
> economy as their piston powered counterparts from what I'd heard. If they've
> managed to improve it, that's great.
Check out various sites on the new Mazda Renesis:
http://www.mazda.co.nz/technology/1178.html
http://www.edmunds.com/news/autoshows/articles/45676/page029.html
http://history.mazda.co.jp/motorshow99/english/concept/evolve/c_responce.htm
> Higher RPM isn't necessarily the point in a helicopter. What's more important,
> I think, is the engines ability to produce usable torque throughout a
> relatively wide RPM band. If this new rotory can do that better than it's
> piston engine cousins, it should make a good candidate.
Well, that's the thing, it can produce good torque all the way upto
several thousand RPM. I don't think that the torque requirements for
aircraft rotors are quite as tough as those for cars, where the rubber
hits the road.
> I can't say I've seen a rotory engine in a helicopter but there are several
> gyroplanes out in the world that have been powered by converted Mazda engines.
Well, I read that the Renesis is being aimed towards aircraft as well.
It appears to then be the most efficient Wankel rotary engine to date.
Might be a really good candidate for a small 2-seat helicopter. I'd
really like to find out more about the fuel economy, though. And
although it says that it's 30% lighter, I still don't know what that
weight is in absolute terms.
Mark Blackwell
Think the biggest problem is not in the engine, but the fact that it turns
at higher rpms and needs a reduction drive to turn the prop or rotor at an
rpm that is effective. I don't know about helicopters but I suspect they
are simular to airplanes and an airplane prop isnt very efficient at over
say 3500 rpms. A high reving engine that doesn't develop hp at low rpms
need a drive that reduce rpms to a point that a prop can work. It can be
done though, but not as easy as you would think
--
Mark Blackwell
http://www.aviatorsonestop.com
Felix Miata
Try here: http://home.earthlink.net/~rotaryeng/
--
A fool gives full vent to his anger, but a wise man keeps himself under
control. Proverbs 29:11 NKJV
Team OS/2 *** Rotary ONLY since 1973
Felix Miata *** http://mrmazda.members.atlantic.net/ <- Not just a FAQ
Capt.Doug
D.
"Jon Williams" <> wrote in message ..
Jon Williams
feasible. You can make them, but most people scoff at them because they are
currently not practical. I've seen weirder shaped aircraft that have
succesfully flown, would you consider the skycar so silly if it wasn't
called a skyCAR but rather just a regular aircraft?
JPW
Ben Sego
> Maybe, but from an engineering point of view those skycars are totally
> feasible.
No. They're not. Not as described (read "hyped") by Moller. That's what
Capt. Doug meant with the PT Barnum inquiry. This subject has been done to
death in rec.aviation.homebuilt. (I'm not sure where you normally post, so I
left the cross-posts in.) Do a dejagoogle search on "Moller skycar", and limit
the group to RAH. Read a bit, if you're interested.
> You can make them, but most people scoff at them because they are
> currently not practical.
No, it's not because they're not practical, it's because, they currently don't
fly. When they begin flying (manned, untethered), _then_ they won't be
practical. Or safe.
> I've seen weirder shaped aircraft that have
> succesfully flown, would you consider the skycar so silly if it wasn't
> called a skyCAR but rather just a regular aircraft?
Call it any damn thing you want to call it, though my vote for the most
accurate name would be "pipe dream." (Though "piltdown plane" was a close
second.) The fact that it has "car" in the name doesn't keep it grounded; so
far physics does. After that, either good sense or the FAA (those being, for
the most part, mutually exclusive) will serve nicely.
Once again, I apologize for the cross-posts; I really only intended this for
RAH.
Ben "deja f'ing vu" Sego
Ray Leonard
<j...@optushome.com.au> wrote:
>Maybe, but from an engineering point of view those skycars are totally
>feasible. You can make them, but most people scoff at them because they are
>currently not practical. I've seen weirder shaped aircraft that have
>succesfully flown, would you consider the skycar so silly if it wasn't
>called a skyCAR but rather just a regular aircraft?
>
From an engineering point of view the performance promises are a
morass of contradictions and pie in the sky. See below.
Ray
On Sat, 24 Jul 1999 13:04:39 GMT, "Dan Hanson"
<danh...@home.com> wrote:
>I just found an article that Peter Garrison wrote for "Flying" in August
>1991 regarding the M400 Skycar. There are some interesting things in there.
>
>Here are some basic specifications for the Skycar:
>
> - It is claimed to have a maximum range of 900 miles, with 240 lbs of
>fuel.
> - It is supposed to cruise at 350 mph.
> - It is powered by 8 rotary engines producing 960 HP, with deflector vanes
>to vector thrust
> - Gross weight is 2400 lbs, and it claims a payload with max fuel of 740
>lbs.
> - Wingspan is 18'
>
>
>Now, here are the problems that Garrison sees with the design:
>
> - According to Moller's drag figures (which Garrison thinks are highly
>optimistic), to maintain the claimed cruise speed the airplane would burn
>40-50 gph, giving it a real range more like 250 miles with reserves.
>
> - Due to the small wing, the induced drag would be very high at lower
>speeds, meaning even an economy cruise would burn gas like mad.
>
> - V/TOL would burn gas at a fiendish rate, further cutting into range.
>
> - To back up his claim of cruise efficiency, Moller plans to shut down 4
>engines, but this would require feathering fans, which are not part of the
>design.
>
>- The rear wing would have a clear-cut stall, but the front ducts wouldn't,
>which is the reverse of what you want in a canard configuration.
>
>- The rear engines are operating in the wash of the front engines, which are
>going to blow all kinds of FOD into them.
>
>- The supposed redundancy of having two engines per duct isn't as safe as it
>looks, since a fan failure would likely take out the whole duct, and a fan
>failure in the front duct could take out both ducts one one side of the
>airplane.
>
>- The Thrust-deflection vanes require a large number of rotating parts
>operating in an unfriendly environment of oil and airborne dust
>
>He didn't go any farther in the article, but it's interesting that he wrote
>the article because Moller was advertising that the M400 was going to fly
>later that year. You have to question the engineering judgement of someone
>who says that an airplane will fly in a few months, and then takes 9 more
>years.
>
>All of the numbers surrounding this thing sound suspect. Moller claims an
>empty weight of 1420 lbs. This for an airplane with 8 engines, fans, and
>subsystems to control them all. It seems to have a lot of frontal area, and
>it looks to me like there would be a ton of interference drag from all the
>struts and supports.
>
>In short, I can't help but think it's all smoke-and-mirrors, yet Moller and
>his team seem highly qualified. What's the scoop?
C.D.Damron
United States, it's a pretty small club of those with that type of
experience. Such efforts would not go unnoticed by the industry.
I would dare Moller to describe the basics of his system or give somebody a
quick glance at the thousands or tens of thousands of lines of code such an
effort would require.
Ray Leonard wrote in message <3b204d3a...@news-byoa.prodigy.net>...
Dave
already here... At least one anyway. ;-)
http://www.usbusiness.com/helicopter/WScor1.htm
On 7 Jun 2001 04:37:23 -0700, sanm...@my-deja.com (sanman) wrote:
BOb U
"Capt.Doug" wrote:
>Was it PT Barnum who said there's a sucker born every day?
>
>D.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Shame on you, Capt. Doug.
For penance bring TWO cases of that special beer to STE.
Here's the real deal...
P.T. himself welcomes you to Ringling Online and the
World Wide Web!
There is no proof that Phineas Taylor Barnum ever said "there's
a sucker born every minute." He did, however, say that "every
crowd has a silver lining," and acknowledged that "the public is
wiser than many imagine."
Plagiarized from....
http://www.ringling.com/history/barnum/
Jon Williams
since there is such a huge force telling me i'm wrong :) I stand corrected
then.
Uhh, i tend to go on a bit sometimes so i'd better stop before i get totally
off topic. :)
JPW
The Raven
news:t9bvhtc72p8pb5rse...@4ax.com...
[snip]
>
> From Mazda's New Zeland website,
> http://www.mazda.co.nz/technology/1178.html
>
> "The Mazda rotary engine is an elegantly simple idea. It has far fewer
> parts and less stress on its components than piston engines. In modern
> form it is highly reliable. So reliable it is now being developed for
> use in aircraft. "
>
> Interesting that MAZDA says someone's working on an aircraft
> application. Wonder what David Orr will have to say about that.... :)
I don't know who David Orr is but there have been several wankel rotary
aircraft over the years. Yes, a majority have been homebuilts but there have
been several production aircraft.
The world's first wankel powered aircraft first flew in 1969. It was built
by Lockheed and powered by a 185HP Curtiss-Wright RC2-60 engine.
Additionally, there was a rotary powered Lockheed Q-Star.
To date, most of the homebuilt aircraft have used modified automotive rotary
engines.
--
The Raven
** Undisputed President of the ozemail.* NG's
** Conqueror of the uunet.* NG's
Russell Kent
Ben Sego wrote:
> After that, either good sense or the FAA (those being, for the most part,
> mutually exclusive) will serve nicely.
Russell Kent
BOb U
That's prrretty good, but when it comes to truth and the FAA,
I'll vote for Joe Norris and his quip...
>> I doubt there are too many people who know all the FAR's by heart.
>Even within the FAA!!! :^)
>Joe
sanman
> In article <BA4A69187AC47066.617D6F02...@lp.airnews.net>,
> main rotor? The main rotors have to be driven as much lower than 3500 rpms.
> The only difference should be the ratio.
>
>
> Bob Reed
Which makes me then wonder, what is the best RPM range for a small
helicopter?
What, in practice, should be the highest reasonable RPM for a small
helicopter?
I have read that the Rotax 582 gives 65 HP @ 5000 RPM. Is that then
the ideal power and RPM for a small helicopter?
If a helicopter's overhear rotor spins slower than a fixed-wing's
propeller, then why wouldn't you want an engine that gives high power
at a lower RPM?
It sounds then like higher power at high RPM is really best-suited for
fixed-wing propellers. It would also be suitable for a gyroplane or
anything that needed to turn a small propeller rapidly. Propellers of
course need higher RPM than large rotors because of their lesser
airfoil surface.
So then Rotary Engines would be best suited for propeller-driven
aircraft, because they offer high power-to-weight ratios and high
RPMs.
While the new Mazda Renesis engine is too heavy for a small helicopter
(140 kg), and it offers more horsepower than is needed (250 HP), it
does seem to be able to provide a nice compression ratio (9:1) without
a turbocharger.
It would however be great if the technological improvements of the
Renesis engine could be passed on to smaller, less powerful rotary
engines, so that these too could offer higher power-to-weight and
efficiency within their size ranges.
Until we see some new small Mazdas, the engines offered by Mid-West
and Wankel Rotary seem to be the best rotaries for small aircraft, for
now. Otherwise, anybody know of any better small rotary than these?
wmbjk
"C.D.Damron" <dam...@lex.infi.net> wrote in message
news:9fpkhu$t7h$1...@nntp9.atl.mindspring.net...
> Just thinking about the on-board real-time processing blows me away. In the
> United States, it's a pretty small club of those with that type of
> experience. Such efforts would not go unnoticed by the industry.
>
> I would dare Moller to describe the basics of his system or give somebody a
> quick glance at the thousands or tens of thousands of lines of code such an
> effort would require.
No need to speculate. I read months ago that it would be flying this month. If
you hear something overhead that sounds like a cross between a hornet's nest and
a heavy metal band, DUCK and COVER!! (And pray that the crane sling was hooked
up right.)
Wayne
Capt.Doug
TWO cases of >that special beer to STE.
Yeah, but he gave up without a good fight. Why don't you remind us how the
old-timers
troll! :-)
D.
Vincent
It was a birotor which produce 190 HP. The first time it was shown was
during the annual french vintage automotive meeting "RETROMOBILE", year 2000
!
I put some pictures on this page
http://www.apcom.fr/eurosmclub/rencontres/retromobile2000/retromobile2000.ht
m
But I have many others.
I have seen also some ROTORWAY Scorpion helos with MAZDA rotary engine on
the Web.
Vincent
Vincent
http://www.apcom.fr/eurosmclub/rencontres/retromobile2000/retromobile2000.ht
m
The final "m" was missing.
Craig C.
>
>Which makes me then wonder, what is the best RPM range for a small
>helicopter?
>What, in practice, should be the highest reasonable RPM for a small
>helicopter?
>
>I have read that the Rotax 582 gives 65 HP @ 5000 RPM. Is that then
>the ideal power and RPM for a small helicopter?
Most main rotor systems turn in the 300 RPM range.....kinda hard to
build a small motor that will provide the necessary power at that rpm
level without the use of massive flywheels.
As to using the Rotax, there have been some issues with the Rotax in
the Mini-500 program where vibrational analysis was either ignored or
poorly done and the result was numerous failures that should not have
occured. Do a search on the Mini-500 in this newsgroup and you can
have a couple of days worth of reading....
As to the "ideal hp and rpm"...it is so design and performance
requirement dependant that you really can't answer this without much
more info. Define the design and the mission requirements and you can
start looking at the hp required to meet them.
Craig C.
mike gray
>
> The french manufacturer CITROEN made two rotary helos between 1975-1979.
>
> It was a birotor which produce 190 HP. The first time it was shown was
> during the annual french vintage automotive meeting "RETROMOBILE", year 2000
Oooooooh, man, cruising down I-95 in my 67 Citroen DS21 Pallas saloon
with a three-rotor humming.... My thighs are getting sticky!
Not so far out - in 1969 there were 500 Citroen M35 coupes with a 49 hp
Wankel made.
m
David
Mark Blackwell wrote:
>
> Think the biggest problem is not in the engine, but the fact that it turns
> at higher rpms and needs a reduction drive to turn the prop or rotor at an
> rpm that is effective. I don't know about helicopters but I suspect they
> are simular to airplanes and an airplane prop isnt very efficient at over
> say 3500 rpms.
With a propeller, you need to keep the prop tips below the sound
barrier...
So, the max RPM is dependent on the prop length.
I've seen a model aircraft with a 74cc two stroke petrol engine spin a
24" prop fast enough to cause a sonic boom. It has nasty effects on the
tips of the prop too.
A high reving engine that doesn't develop hp at low rpms
> need a drive that reduce rpms to a point that a prop can work. It can be
> done though, but not as easy as you would think
> --
> Mark Blackwell
> http://www.aviatorsonestop.com
--
Dave
****
"It's all just a load of Klatchian to me..."
Rincewind
****
Stu Padaso
"Flying Machine Soars Three Miles in Teeth of High Wind Over Sand
Hills and Waves at Kitty Hawk on Carolina Coast: No Balloon Attached
to Aid It; Three Years of Hard, Secret Work by Two Ohio Brothers
Crowned With Success; Accomplished What Langley Failed at; With Man as
Passenger Huge Machine Flew Like Bird Under Perfect Control; Box Kite
Principle With Two Propellers," Virginian-Pilot, Dec. 18, 1903
sanman
> barrier...
> So, the max RPM is dependent on the prop length.
>
> I've seen a model aircraft with a 74cc two stroke petrol engine spin a
> 24" prop fast enough to cause a sonic boom. It has nasty effects on the
> tips of the prop too.
Yeah, but a rotor thwip-thwips thru the sound barrier all the time, so
it wouldn't be an issue for a helicopter. But I'm assuming that a
helicopter would have Max RPMs limited by the strain on the
transmission.
I was looking at the Masquito helicopter ( www.masquito.be ) under
development, and it looks like they don't really have much of a
transmission, which is why they run their Jabiru 2200 engine
vertically, and modified for higher RPMs.
Still, I don't understand why they modified the Jabiru to do higher
RPMs, if all helicopters require a reduction drive to begin with.
Isn't that contradictory?
Charlie and Tupper England
>
> Hi,
>
> I was reading about Wankel rotary engines, including the new improved
> Mazda Renesis engine. They seem to provide higher RPMs and more power,
> with lower weight and compact size, as well as less vibration. I'd
> like to then know why a rotary engine such as the Renesis wouldn't be
> nice for a small helicopter type of aircraft?
>
> I'd read that with rotary engines, one big issue is adequate airflow,
> but I'd assume that the airflow with an aircraft caters to that issue
> quite well.
>
> I'd heard some say that rotary engines aren't quite as good on fuel
> economy as a piston engine, but that the new Renesis may have closed
> the gap or even taken a lead.
>
> The whole higher RPMs idea seems to cater to the needs of a helicopter
> quite well. I'd also wonder how the engine reliability would compare,
> such as in avoiding engine stalls, etc.
>
> Is there any information on the net, on how to fit a rotary engine to
> a small helicopter or even a gyroplane?
several Mazda's are flying on gyros.
Ben Sego
Yeah, he was too easy. I thought it was going to be the usual protracted
exchange, where eventually somebody makes fun of the designer or the people who
have died or will die in the design, and then somebody else will tell us that
the people that have died or will die had a family and people who loved them,
or will have a family and people who loved them, then the offending poster will
point out that it is our nature to use humour (note spelling) to ease the pain
of difficult situations, and that as pilots and caring human beings it is our
responsibility to learn from the mistakes of others and our duty to bring the
issue before the eyes of the uninitiate that they might also be spared, and
then the complaining poster will say that it's not funny and there are better
ways to do it and then the offending poster will tell us that if he does
something in an aircraft that qualifies him for the Darwin award that he damn
well _expects_ his friends to make fun of him in eulogy, and then the offended
poster will slink away, but it won't matter because most people will have
started ignoring him. You know _that_ exchange? That's what I expected.
Ben "As I lay Dying" Sego
Joe Norris
> it wouldn't be an issue for a helicopter.
Huh? What gave you that idea? Ever actually figured out the tip speeds of
a helicopter rotor? Check it out sometime!
Joe Norris
Craig C.
Run the calculations.....For the Huey/Cobra main rotors, the outboard
foot or so almost always has supersonic flow when it is the advancing
blade. That is what give them the unique sound in forward flight.
Ch-47 has a considerable amount of problems with the tips being
supersonic, but due to realities, has a lot of destructive
interference, so you don't get as much pop off the tips.
Even the JetRanger, the Astar and TwinStars will get the tips going
mildly supersonic in certain flight regiemes. It's just that most
people try and not operate in that part of the envelope with the
smaller birds as it is hard on everyone in the cabin.
Craig C.
Floyd Dan
more errors in sanmans comments:
To quote sanman again:
I was looking at the Masquito helicopter ( www.masquito.be ) under
development, and it looks like they don't really have much of a
transmission, which is why they run their Jabiru 2200 engine
vertically, and modified for higher RPMs.
Still, I don't understand why they modified the Jabiru to do higher
RPMs, if all helicopters require a reduction drive to begin with.
Isn't that contradictory?
sanman, you are in error;
_Yes they do have a transmission.
_The engine appears to be mounted horizontally, not vertically.
_The reason they run the 2.2 liter Jabiru at higher than normal rpms
is to increase HP as explained on the web site.
The engine makes its power at 3700 rpm. The reduction gearing lowers this to 690
which is very high for a helicopter, but the rotor diameter is small.
The tip speed is only 60% of the speed of sound.
Floyd Dan
Vincent
What is "three-rotor humming" ?
Only 267 M35 Coupe were made.
Vincent
sanman
Thanks for the corrections, Floyd. Hmm, but then why do they comment
that they preferred Jabiru because it was one of the only engines
rated for vertical operation? Otherwise why say it, if they weren't
mounting and operating that engine vertically?
Anyhow, it's surprising that they went to the extent of redesigning
that engine rather than simply getting one with a higher power rating.
I would think that a MidWest rotary engine would show a superior
power-to-weight ratio, with best power at the higher RPMs that the
smaller rotor needs.
Ian Stirling
>"Joe Norris" <jnorri...@tznet.com> wrote in message news:<K0qU6.34521$Uo3.11
>77...@news6.giganews.com>...
>> > Yeah, but a rotor thwip-thwips thru the sound barrier all the time, so
>> > it wouldn't be an issue for a helicopter.
>>
>> Huh? What gave you that idea? Ever actually figured out the tip speeds of
>> a helicopter rotor? Check it out sometime!
>>
>> Joe Norris
>more errors in sanmans comments:
>To quote sanman again:
>I was looking at the Masquito helicopter ( www.masquito.be ) under
>development, and it looks like they don't really have much of a
>transmission, which is why they run their Jabiru 2200 engine
>vertically, and modified for higher RPMs.
>Still, I don't understand why they modified the Jabiru to do higher
>RPMs, if all helicopters require a reduction drive to begin with.
>Isn't that contradictory?
If increasing the RPM increases the horsepower, then that may be the
reason.
--
http://inquisitor.i.am/ | mailto:inqui...@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
He who lives in a glass house should not invite he who is without sin.
mike gray
>
> Do you always own it ?
Naw. Just a wet dream. A fantasy. A very erotic fantasy
>
> What is "three-rotor humming" ?
About 50% more hp than a two-rotor humming. The way we Mazda folks
hot-rod a rotary. Just keep stacking those rotors. There are some
four-rotors around, but the engine bay is more accomodating of three.
Tuners like Pettit and Racing Beat offer them off-the-shelf.
> Only 267 M35 Coupe were made.
I'll take yer word. Georgano says 500.
m
Rod Buck
Stirling <Inqui...@I.am> writes
>>Still, I don't understand why they modified the Jabiru to do higher
>>RPMs, if all helicopters require a reduction drive to begin with.
>>Isn't that contradictory?
>
>If increasing the RPM increases the horsepower, then that may be the
>reason.
>
I mean ANY engine needs a reduction box to match it's speed to the
reduced main rotor speed .
NO small engine produces power at 300-600 rpm, at the necessary torque!
Therefore you need a reduction box. Not just to reduce rpm, but to
multiply torque.
Therefore, it matters not if your chosen engine produces its power at
2500 rpm, or at 6000 rpm - just choose the reduction drive ratios to
produce the desired output rpm and torque?
Mind you, in piston engines, there may be a reason to choose lower-
revving engine - reliability, due to reduced piston speed. Particularly
in helo use.
The lower the revs, the less the stress, so reliability increases,
generally.
However, with a rotary engine, which may be happier at higher rpm, just
use a box with a higher reduction ratio.
- Rod Buck
BOb U
Thanks for filling in, Ben. <g>
BOb U
Badwater Bill
>
>more errors in sanmans comments:
>To quote sanman again:
>I was looking at the Masquito helicopter ( www.masquito.be ) under
>development, and it looks like they don't really have much of a
>transmission, which is why they run their Jabiru 2200 engine
>vertically, and modified for higher RPMs.
Sanman:
Horsepower is equal to (torque) x (rpm)/5252 in the English unit
system, i.e. torque in foot-pounds. If the torque curve is relatively
flat with rpm, then an increase in rpm provides a comensurate increase
in horsepower. That's why they spin it faster.
Just think about it, if you double the rpms, you eat twice the air,
twice the fuel...etc. and you get twice the power output (within
limits).
This is exactly what they do in the Exec (Rotorway) helicopters, and
even the Enstrom. They BUZZ that engine to get the hp they need.
Badwater Bill
Kenny P
the published specs of the SkyCar.
A snippet: ": ~ .12 lbs./hp/hr to meet the goals "
The numbers were IMPOSSIBLE. The required
specific fuel consumption was more than an
order of magnitude better than what is currently
feasible today ... or tomorrow.
Although ... the flying boat anchor might reach its projected
speed ... upon running out of fuel.
BTW, I use the phrase 'order of magnitude' to mean
exactly that: the fifth root of 100, or ~2.51. Betcha
didn't know that!
Kenny P.
"Richard Riley" <richard*NOSPAM*@riley.net> wrote in message
news:q1j0ito6f31f9atkb...@4ax.com...
> At some point in the past, ( Fri, 08 Jun 2001 03:20:55 GMT, as it
> happens) someone using the name "Jon Williams" <j...@optushome.com.au>
> made the following views known to all those in rec.aviation.homebuilt
> >Maybe, but from an engineering point of view those skycars are totally
> >feasible. You can make them, but most people scoff at them because they
are
> >currently not practical. I've seen weirder shaped aircraft that have
> >succesfully flown, would you consider the skycar so silly if it wasn't
> >called a skyCAR but rather just a regular aircraft?
>
> No, we'd still think it's silly. There was a very good post on RAH a
> few months ago running the fuel consumption numbers. Everything else
> about Moller is theoretically possible (once you assume a bunch of
> stuff about government regulation, robotics, and the mindset of the
> general public) but the fuel consumption is something that can't be
> overcome.
>
> --
>
> Richard Riley
>
> Vote Cthulhu for President!
> Don't settle for a lesser evil!
Ron Natalie
Kenny P wrote:
>
> BTW, I use the phrase 'order of magnitude' to mean
> exactly that: the fifth root of 100, or ~2.51. Betcha
> didn't know that!
>
Only if you're an astronomer with imprecise use of terminology.
The astronomical term is just "magnitude" (without "order of").
The correct statement would be "the Moller requires a magnitude
better specific fuel consumption than current technology can provide."
If you use the term "order of magnitude" with bases other than 10,
people will think you are daffy.
But I generally agree, my II/6 1934 Moller Pipe Organ (Opus 5967)
probably has a better chance of flying.
Ken Sandyeggo
> that they preferred Jabiru because it was one of the only engines
> rated for vertical operation? Otherwise why say it, if they weren't
> mounting and operating that engine vertically?
>
By "vertical operation," I believe they mean a craft that flies
vertically, not the engine stood on end. That's the way I'm reading
it. "Vertical operation" to me has always meant vertical flight, not
engine orientation, but different terms are used differently in
different parts of the world, so could be.
Ken J. - Sandy, egg ho
Kenny P
Whether imprecise or not, the phrase
'order of magnitude' is commonly used ... even
by astronomers.
Although I am usually the one
pointing out improper and imprecise and redundant
speech ;-]
I was disturbed when the convention for pronouncing
'giga' as a prefix veered from 'giant' ... we used to say
"jiggahertz" in reference to a radar system!
But ...
That Moller thingy will never do all of the things the
good doctor says ...
KP
And make sure that you video Venus slipping behind
the crescent moon in the daylight. I will be. It should
be visible to the naked eye.
"Ron Natalie" <r...@spamcop.net> wrote in message
news:3B250A34...@spamcop.net...
Ron Natalie
Kenny P wrote:
> I was disturbed when the convention for pronouncing
> 'giga' as a prefix veered from 'giant' ... we used to say
> "jiggahertz" in reference to a radar system!
No, the prefix giga (as with most of the the prefixes)
comes from the greek. The word is not giant, but
gigas (which means giant). The soft-g sound for giant
in English comes from the French (and probably so did
the soft-g for gigahertz, as most of the SI stuff seems
to have been hammered out in Paris). The Greeks used
a hard g.
Jon Williams
speeds, range etc rather than saying it just won't fly at all?
JPW
Richard Riley
I'm saying that with enough money, man hours and engineering talent
thrown at it, it could fly. At a wild guess, it would take 10 to 100
times the resources currently being applied to it, and at that point
it wouldn't fly as well, as cheaply or as safely as aircraft flying
today.
I'm also saying that unless we completely rewrite the laws of physics,
it won't come close to meeting it's published specs.
The fact that they keep publishing such absurd specs is a strong
indication to me that it's a complete and purposeful fraud, rather
than a good effort that might or might not work.
Think of it in automotive terms. If someone were flogging investors
for a new car that would use an alcohol powered fuel cell to run a
Corolla sized vehicle, at Corolla type speeds, but would get 60 MPG,
it's within the realm of possibility. Look deeper, see what's the
critical technology that needs to be developed, what's the track
record of the people in charge of the financial and technical side,
look at the market, and decide if you want to risk the money.
But if they were flogging investors for a solar powered Ferrari that
will do 0-60 in 2.1 seconds, have a 460 mph top speed, unlimited
range, never needs gas and only needs to be parked in the sun half an
hour per day, I'd think you should hold on to your money.
Paul Baechler
kensan...@msn.com (Ken Sandyeggo) wrote:
>By "vertical operation," I believe they mean a craft that flies
>vertically, not the engine stood on end. That's the way I'm reading
>it. "Vertical operation" to me has always meant vertical flight, not
>engine orientation, but different terms are used differently in
>different parts of the world, so could be.
When Franklin and Lycoming used "vertical" they referred to engine
orientation. The engine shouldn't care if it's mounted in a craft that
flies vertically or in a ground power unit, so long as its operating
limits are not exceeded.
--
Paul Baechler
pbae...@bellsouth.net
Kenny P
get MORE investors!
KP
"Jon Williams" <j...@optushome.com.au> wrote in message
news:hYbV6.5222$l_3....@news1.rochd1.qld.optushome.com.au...
highflyer
>
> So are you people really saying that it just won't meet their specified max.
> speeds, range etc rather than saying it just won't fly at all?
>
I doubt that it can be made to fly with any kind of reasonable safety
and control. However, there is NO way their specs can be met without
seriously violating all of the accumulated body of knowledge concerning
heat engines and fuel consumption. :-)
--
HighFlyer
Highflight Aviation Services
clayton ashley
David B Brownell
The ultimate efficiency in an internal combustion engine would be a
combustion chamber that would be spherical in shape, that would expand
and contract in diameter. A sphere has the greatest volume for it's
surface area than any other geometric shape, therefore the heat loss
will be the lowest for the operational displacement, hens, highest
fuel/thermal efficiency.
In second place, there is a geometric shape called a cylinder!
Very high insulation qualities would boost the efficiency of both
combustion chamber types.
Dave Brownell
DB Technologies
Mesa, AZ
Dave Jackson
Mini 500's to rotary.
Their web site is: http://stittind.com/
"sanman" <sanm...@my-deja.com> wrote in message
news:f69a20c6.01060...@posting.google.com...
The Raven
news:e1b015c3.01061...@posting.google.com...
> ATTN: Reality Speaking!
>
> The ultimate efficiency in an internal combustion engine would be a
> combustion chamber that would be spherical in shape, that would expand
> and contract in diameter.
And if anyone can figure out how to do that for a mass produced low cost
automotive engine they'll be able to buy Bill Gates out.
> A sphere has the greatest volume for it's
> surface area than any other geometric shape, therefore the heat loss
> will be the lowest for the operational displacement, hens, highest
> fuel/thermal efficiency.
>
> In second place, there is a geometric shape called a cylinder!
And a cylinder with a true hemispherical piston and combustion chamber would
need to be quite large (in stroke) to be able to generate sufficient
compression ratio. The next challenge would be to get a spark plug to hover
in the exact centre of the sphere formed at TDC. How you get the intake and
exhaust to work will also be a challenge, seeing a valves wouldn't make the
chamber truely spherical.
It's an interesting concept that's probably been tried and may prove
possible in the future. For the moment I think it's not very practical.
>
> Very high insulation qualities would boost the efficiency of both
> combustion chamber types.
Something along the lines of the adiabatic engine concept (from vague
memory)?
--
The Raven
** Undisputed President of the ozemail.* NG's
** Conqueror of the uunet.* NG's
David B Brownell
And a cylinder with a true hemispherical piston and combustion chamber
would need to be quite large
(in stroke) to be able to generate sufficient compression ratio. The
next challenge would be to get a spark plug to hover in the exact
centre of the sphere formed at TDC. How you get the intake and exhaust
to work will also be a challenge, seeing a valves wouldn't make the
chamber truly spherical.
DB> When I said-- "In second place, there is a geometric shape called
a cylinder!,"
the word spherical was not used; as a matter of fact, as far as a
piston engine is concerned, having a hemispherical piston head and
cylinder head would decrease efficiency, as the surface area created
by the sphere at top dead center would add surface area to the "swept
volume" (displacement) of the engine.
This "created sphere" at top dead center is not part of the "swept
volume" (displacement) of the engine.
(displacement=Bore:Stroke Pi R^2 H --period)
A piston engine has the lowest surface area for it's "swept volume"
(displacement) with a flat top piston, and a flat surface cylinder
head.
Dave Brownell
DB Technologies