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  #1  
Old August 11th 04, 04:23 PM
Peter Holm
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Default turbo video

Hi,

I donīt know much about aerobatics, but I would love to see a video of
an aerobatic airplane with turboprop engine doing the vertical climb
and the torque roll. A search with the Google machine for "turboprop,
video" on this forum didnīt give me any results. Does anyone here know
about such a video and where I can see it?

Thanks!

Peter
  #2  
Old August 17th 04, 05:12 AM
John Clear
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Default

In article ,
Peter Holm wrote:

I donīt know much about aerobatics, but I would love to see a video of
an aerobatic airplane with turboprop engine doing the vertical climb
and the torque roll. A search with the Google machine for "turboprop,
video" on this forum didnīt give me any results. Does anyone here know
about such a video and where I can see it?


Do a search on 'Turbo Raven'. Wayne Handley's site doesn't appear
to have video, but there is probably some out there. Unfortunately,
the Turbo Raven was only flown for one season.

http://www.waynehandley.com/archive.html

John
--
John Clear - http://www.panix.com/~jac

  #3  
Old September 17th 04, 04:07 AM
Peter Holm
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Default

Itīs been a while and I have been rather busy, but I nevertheless
didnīt want to let pass the deadline for responding.

(John Clear) wrote in message ...
(cut)
Do a search on 'Turbo Raven'. Wayne Handley's site doesn't appear
to have video, but there is probably some out there. Unfortunately,
the Turbo Raven was only flown for one season.

http://www.waynehandley.com/archive.html

John


Besides you, there has been one other person answering to my mailbox.
And that answer referred itself to the Turbo Raven as well. But I
havenīt yet found any video of that aircraft. In fact, it seems to me
as if that aircraft has been the only dedicated turboprop aerobatic
aircraft that was ever flown. And that there is nothing today. Am I
wrong on that?

Just in case that I am right:
I know that a turboprop airplane can easily cost twice as much as a
piston plane of the same size. But this fact could only explain a
relative rareness of turboprop airplanes among aerobatic planes. What
it cannot explain is their (next to?) absence, since experience shows
that if there is a will there is a way, and some or another team of
people should always be able to adquire one of these planes.

If I extrapolate by scale from what I have frequently seen with model
aircraft (which tend to have a much higher power to weight ratio than
full scale aircraft), an aerobatic turboprop plane should be able to
execute a sustained torque roll at 10 or 15 feet above ground. And
that ought to be an absolutely awsome sight! Has anybody ever done
that?

But now I think that - sadly - I will never get to see that, and I am
starting to wonder why.

I know that piston engines can have certain advantages under certain
conditions: For example, when it comes to propulsion on a solid
surface (greater range of rpmīs), or when it comes to the
transportation of large amounts of goods at a minimal price on a
liquid medium (fuel eficiency). But when it comes to airplanes, I can
see that turbo engines are employed either next to exclusively
(commercial/military airplanes) or at least frequently
(private/business airplanes), exept in the case of crop dusters - and
aerobatic airplanes. Now I can understand that turbo crop dusters make
little sense, but how about in the case aerobatic airplanes?

Therefore, my question is (always assuming that my basic assumption
above is correct):

Is there a rational reason for the next to absence of turboprop planes
among aerobatic aircraft, or is this absence perhaps due to some sort
of stubborn romanticism?

Peter
  #4  
Old September 17th 04, 11:06 AM
Byron J. Covey
external usenet poster
 
Posts: n/a
Default

Peter:

"Peter Holm" wrote in message
om...
Itīs been a while and I have been rather busy, but I nevertheless
didnīt want to let pass the deadline for responding.

(John Clear) wrote in message
...
(cut)
Do a search on 'Turbo Raven'. Wayne Handley's site doesn't appear
to have video, but there is probably some out there. Unfortunately,
the Turbo Raven was only flown for one season.

http://www.waynehandley.com/archive.html

John


Besides you, there has been one other person answering to my mailbox.
And that answer referred itself to the Turbo Raven as well. But I
havenīt yet found any video of that aircraft. In fact, it seems to me
as if that aircraft has been the only dedicated turboprop aerobatic
aircraft that was ever flown. And that there is nothing today. Am I
wrong on that?


The first that I saw was a turbo Great Lakes, sponsored by Mennen (the
aftershave company.) It used smoke that smelled like the aftershave, and
did a vertical S ontakeoff. That was in the eaarly 1970's as best as I
remember.

The Turbo Raven flew for a short time before the crash.

There is a turbo Sukohi that Ihave seen photos of, but I haven's seen it
live.


Just in case that I am right:
I know that a turboprop airplane can easily cost twice as much as a
piston plane of the same size. But this fact could only explain a
relative rareness of turboprop airplanes among aerobatic planes. What
it cannot explain is their (next to?) absence, since experience shows
that if there is a will there is a way, and some or another team of
people should always be able to adquire one of these planes.


Just a SWAG, but I would think that the Turbo Raven cost about 6 times what
a good Edge 540 would cost. Sponsorship before construction would be
important.

If I extrapolate by scale from what I have frequently seen with model
aircraft (which tend to have a much higher power to weight ratio than
full scale aircraft), an aerobatic turboprop plane should be able to
execute a sustained torque roll at 10 or 15 feet above ground. And
that ought to be an absolutely awsome sight! Has anybody ever done
that?

Doins so would be betting one's life and airplane on no wind gusts,
absolutely no pilot miscalculation, and no aircraft / engine problem.

I have seen the Turbo Raven hover, descend vertically, then ascend
vertically. Scary to watch.

But now I think that - sadly - I will never get to see that, and I am
starting to wonder why.


Rich and foolish is not a combination that survives long.

I know that piston engines can have certain advantages under certain
conditions: For example, when it comes to propulsion on a solid
surface (greater range of rpmīs), or when it comes to the
transportation of large amounts of goods at a minimal price on a
liquid medium (fuel eficiency). But when it comes to airplanes, I can
see that turbo engines are employed either next to exclusively
(commercial/military airplanes) or at least frequently
(private/business airplanes), exept in the case of crop dusters - and
aerobatic airplanes. Now I can understand that turbo crop dusters make
little sense, but how about in the case aerobatic airplanes?


Turb crop dusters make lots of sense for large scale application, are
numerous, ane are profittable.

Therefore, my question is (always assuming that my basic assumption
above is correct):

Is there a rational reason for the next to absence of turboprop planes
among aerobatic aircraft, or is this absence perhaps due to some sort
of stubborn romanticism?


Cost is a rational reason. Turbine engines are not allowed in international
aerobatic competition.

Peter


BJC


  #5  
Old September 17th 04, 07:38 PM
Peter Ashwood-Smith C-GZRO
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Posts: n/a
Default

Is there a rational reason for the next to absence of turboprop planes
among aerobatic aircraft, or is this absence perhaps due to some sort
of stubborn romanticism?


There are actually a number of tubro powered aerobatic planes, think
for example of the PT-6 trainers.

For competition aerobatics however which includes lots of gyroscopic
forces, there are I believe concerns about the long shafts in those
engines and the huge gyroscopic forces at work. That would limit them
to sportsman stuff .. which is quite a restriction for a $1,000,000 +
airplane.

I suspect also the time required to spool up/down the power is an
issue.

Peter
  #6  
Old September 17th 04, 10:12 PM
nametab
external usenet poster
 
Posts: n/a
Default

Power reaction is not such an issue for a single-shaft engine. My engine can
go from 10-90% torque in one second, no problem.

However, you did hit on the larger problem: Very high gyroscopic forces.
Although the spinning mass is not very large, my engine turns at 43,500rpm.
That's loads of gyro. I have to be very careful not to snap against the
engine or I might just loose it.

BTY, I fly aerobatic helicopters, so there's a larger gyroscope to deal
with, but it "flies"...

"Peter Ashwood-Smith C-GZRO" wrote in message
om...
Is there a rational reason for the next to absence of turboprop planes
among aerobatic aircraft, or is this absence perhaps due to some sort
of stubborn romanticism?


There are actually a number of tubro powered aerobatic planes, think
for example of the PT-6 trainers.

For competition aerobatics however which includes lots of gyroscopic
forces, there are I believe concerns about the long shafts in those
engines and the huge gyroscopic forces at work. That would limit them
to sportsman stuff .. which is quite a restriction for a $1,000,000 +
airplane.

I suspect also the time required to spool up/down the power is an
issue.

Peter



  #7  
Old September 19th 04, 07:40 AM
John Clear
external usenet poster
 
Posts: n/a
Default

In article ,
Byron J. Covey wrote:
Just in case that I am right:
I know that a turboprop airplane can easily cost twice as much as a
piston plane of the same size. But this fact could only explain a
relative rareness of turboprop airplanes among aerobatic planes. What
it cannot explain is their (next to?) absence, since experience shows
that if there is a will there is a way, and some or another team of
people should always be able to adquire one of these planes.


Just a SWAG, but I would think that the Turbo Raven cost about 6 times what
a good Edge 540 would cost. Sponsorship before construction would be
important.


Larry Ellison, CEO of Oracle, and owner of many big boy toys, is
also a fan of aviation. The story goes that he was talking with
Wayne Handley and Sean Tucker after some airshow, and they hatched
the idea of the Turbo Raven. Cost isn't much of an issue for Larry
Ellison, since he is way up there on the various 'richest people'
lists.

Another post mentioned the difference between aerobatics and
competition aerobatics. The T-6A and various other trainers are
aerobatic turboprops, but they don't have to worry about staying
in the competition aerobatic box, which is quite tiny. The cost of
a turboprop, and the size of the box are probably the main reasons
they aren't used on competition planes. The maintenance requirements
on the turboprop would probably also be an issue.

The Turbo Raven was just a show plane, in the same category as the
jet powered Waco. Fun to watch, but totally ridiculous.

John
--
John Clear - http://www.panix.com/~jac

  #8  
Old September 19th 04, 04:19 PM
nametab
external usenet poster
 
Posts: n/a
Default

Turbines are not more difficult to maintain. In fact the maintenance is much
lower on a turbine (on a per-hour basis). The cost of the overhaul is quite
different though! However, the TBO is much better for a turbine. Overhaul on
my turbine is about US$235,000 but I get 3000 hours out of it. It's quite a
bit more expensive than other turbines, but you still are in the US$100,000
zone for an overhaul of a 600hp+ engine.

How much would a 600hp piston engine cost to overhaul?

"John Clear" wrote in message
...
In article ,
Byron J. Covey wrote:
Just in case that I am right:
I know that a turboprop airplane can easily cost twice as much as a
piston plane of the same size. But this fact could only explain a
relative rareness of turboprop airplanes among aerobatic planes. What
it cannot explain is their (next to?) absence, since experience shows
that if there is a will there is a way, and some or another team of
people should always be able to adquire one of these planes.


Just a SWAG, but I would think that the Turbo Raven cost about 6 times

what
a good Edge 540 would cost. Sponsorship before construction would be
important.


Larry Ellison, CEO of Oracle, and owner of many big boy toys, is
also a fan of aviation. The story goes that he was talking with
Wayne Handley and Sean Tucker after some airshow, and they hatched
the idea of the Turbo Raven. Cost isn't much of an issue for Larry
Ellison, since he is way up there on the various 'richest people'
lists.

Another post mentioned the difference between aerobatics and
competition aerobatics. The T-6A and various other trainers are
aerobatic turboprops, but they don't have to worry about staying
in the competition aerobatic box, which is quite tiny. The cost of
a turboprop, and the size of the box are probably the main reasons
they aren't used on competition planes. The maintenance requirements
on the turboprop would probably also be an issue.

The Turbo Raven was just a show plane, in the same category as the
jet powered Waco. Fun to watch, but totally ridiculous.

John
--
John Clear - http://www.panix.com/~jac



  #9  
Old September 26th 04, 04:33 PM
Peter Holm
external usenet poster
 
Posts: n/a
Default

"nametab" wrote in message k.net...
Power reaction is not such an issue for a single-shaft engine. My engine can
go from 10-90% torque in one second, no problem.

However, you did hit on the larger problem: Very high gyroscopic forces.
Although the spinning mass is not very large, my engine turns at 43,500rpm.
That's loads of gyro. I have to be very careful not to snap against the
engine or I might just loose it.

BTY, I fly aerobatic helicopters, so there's a larger gyroscope to deal
with, but it "flies"...

"Peter Ashwood-Smith C-GZRO" wrote in message
om...

(cut)
There are actually a number of tubro powered aerobatic planes, think
for example of the PT-6 trainers.


Where and when do they fly?


For competition aerobatics however which includes lots of gyroscopic
forces, there are I believe concerns about the long shafts in those
engines and the huge gyroscopic forces at work. That would limit them
to sportsman stuff .. which is quite a restriction for a $1,000,000 +
airplane.

(cut)

Because you are flying such a large gyroscope, I wonder if you might
not be overestimating the gyroscopic forces produced by turboprop
engines. Because in distiction to what Peter Ashwood-Smith is saying
above, small turboprop motors only appear to have a long rotor shaft.
In reality they have two shafts mounted separately one behind the
other: The (single) rotor shaft and the power shaft (with the
reduction gears in front of the latter).

I can really speak competently only about model aircraft turboprops.
And the weight ratio of rotor shaft weight/total aircraft weight
should be at least equal if not higher in model aircraft than in real
aircraft. Besides, microturbine rotor shafts rotate at speeds
typically between 120.000 and 200.000 rpm. And in model aircraft, the
guroscopic forces from the rotor shaft are considered to be
negligible. I donīt see how this could be due to some sort of scaling
effect.

So in order to put an end to all of this speculation, I think what
would really be needed here is the testimony of a pilot who has
actually flown aerobatics with a turboprop plane.


One additional question for you out of interest: Do you believe that
aerobatic turboshaft helicopters are relatively more abundant than
aerobatic turboprop planes? And if yes, why would that be so? After
all, this appears to be contradictory since the pilot of an aerobatic
turboshaft helicopter ought to have to deal with much higher
gyroscopic forces than the pilot of an aerobatic turboprop plane.

Peter H.
  #10  
Old September 26th 04, 04:40 PM
Peter Holm
external usenet poster
 
Posts: n/a
Default

(John Clear) wrote in message ...
(cut)
Larry Ellison, CEO of Oracle, and owner of many big boy toys, is
also a fan of aviation. The story goes that he was talking with
Wayne Handley and Sean Tucker after some airshow, and they hatched
the idea of the Turbo Raven. Cost isn't much of an issue for Larry
Ellison, since he is way up there on the various 'richest people'
lists.


As you concede yourself, when it comes to aerobatic airplanes there
exists a source of financing which generallty doesnīt exist for
private airplanes: Sponsoring. Therefore, the cost argument in itself
can only explain the relative scarcity of turboprop engines in private
aircraft, but not the near absence of turboprop engines in aerobatic
aircraft.


Another post mentioned the difference between aerobatics and
competition aerobatics. The T-6A and various other trainers are
aerobatic turboprops, but they don't have to worry about staying
in the competition aerobatic box, which is quite tiny. The cost of
a turboprop, and the size of the box are probably the main reasons
they aren't used on competition planes.


If the competition aerobatic box tends to be too small for turboprop
planes, then it is inconceivable why they do not install a greater
competition box for turboprop planes.

The maintenance requirements
on the turboprop would probably also be an issue.

The Turbo Raven was just a show plane, in the same category as the
jet powered Waco. Fun to watch, but totally ridiculous.

John


Well now, this jet powered Whacko is nothing but a piston biplane
with a turbojet strapped to its belly. And this turbojet engine has a
bent exhaust pipe - kind of like a turboprop. As long as I havenīt
seen more data on this plane or seen it fly, I wonīt believe that this
setup has much more than decorative value.

And now you come and compare this thing with .... a classical
turboprop plane? Sorry, but thatīs what I would call ridiculous. You
know as well as I do, that turbomachinery rules the airwaves - exept
for a relative scarcity among private airplanes and a next to absence
among aerobatic aircraft. And this is clearly a non trivial fact which
requires a cogent explanation.

Peter H.
 




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