Max. Airship Speed?
Chris Morton
I've always wondered what this was, given that the basic shape could be very
aerodynamically clean, depending upon how the envelope and engines were
configured.
Any sort of propulsion, including jets is fair game.
Thanks.
Tony Williams
I suspect that a limiting factor would be wind pressure against the
nose of the airship. This is serious with current non-rigids, as their
shape is only maintained by internal pressure. It was less of a
problem with the old rigids which had a metal framework, but even so
they were clad with cloth. As speeds increased, the nose would have to
be more strongly constructed to retain its shape, therefore heavier.
--
Tony Williams
New book: Rapid Fire - The Development of Automatic Cannon, Heavy
Machine Guns and their Ammunition for Armies, Navies and Air Forces.
Details on my website:
http://www.users.globalnet.co.uk/~autogun/
Sent via Deja.com
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David Bromage
> What are the maximum theoretical and practical speeds for a rigid airship?
I recall reading somewhere that it's about 100kts. Beyond that, the energy
required for propulsion (big blunt nose) is greater than for lift and
thrust for fixed wings to carry a similar payload. Of course, the actual
number varies with the size of the ship.
Cheers
David
John Parkinson
I recall a documentary on the Hindenberg which put the max speed at 130kts
Regards,
John
"Chris Morton" <cmo...@newsguy.com> wrote in message
news:95kbn...@drn.newsguy.com...
Jörg Bihlmayr
Hindenburg.
Jörg
Chris Morton schrieb:
Randy Appleton
>Hi Chris,
>
>I recall a documentary on the Hindenberg which put the max speed at 130kts
>
knots, and max speed not *much* higher.
-Randy
--
========================================================================
|| Randy Appleton, Professor of Computer Science at Northern Michigan ||
|| University. And a big fan of Linux! ||
================= mailto:ra...@euclid.nmu.edu ==========================
John Parkinson
If this is the case, the documentary must have been talking in km/h. A
website I just looked at confirms this, putting the max speed at 84.4mph or
135 km/h. I stand corrected.
http://people.goplay.com/llb/hinden.html
Regards,
John
"Randy Appleton" <ra...@euclid.nmu.edu> wrote in message
news:slrn97uubu...@euclid.nmu.edu...
Bill Shatzer
On Tue, 6 Feb 2001, Randy Appleton wrote:
> On Mon, 05 Feb 2001 08:36:11 GMT, John Parkinson <jay...@bigpond.com> wrote:
> >Hi Chris,
> >I recall a documentary on the Hindenberg which put the max speed at 130kts
> In _Graf Zeplin and Hindenburg_ the cruise speed of both was around 70-80
> knots, and max speed not *much* higher.
Maximum speed for USS Akron and Macon is given as 75.6 knots - which if my
mental conversion calculator is working correctly, translates to a smidge
under 87 mph.
Cheers and all,
joe_...@my-deja.com
> The conventional cigar shaped hull acts as a crude airfoil
> and as such creates both lift and drag.
Every once in a while somebody comes up with an idea for making a
"hybrid" airship that is shaped more frankly like an airfoil (and less
like a frank? :), usually with the goal of a more economical hauler for
heavy or bulky cargo. Memories of the company described in John
McPhee's old book _the Deltoid Pumpkin Seed_ come to mind. This sort of
thing seems to be undergoing a resurgence, as are ideas for large
airships in the traditional cigar shape, e.g.,
http://www.airship.com/prod/skycat_frames.htm
vis-a-vis
http://www.hamilton.co.za/Home2.htm
or
http://www.aerospace-technology.com/projects/cargolifter/index.html
Most of them seem to dream of a niche that's a lot faster than oceangoing
ships and cheaper to operate or greater in certain aspects of capacity
than cargo airplanes. I'm not well qualified to judge the prospects of
either the individual technologies or the marketing aspects; just thought
you might find it interesting.
Note also some potential military applications besides airlift.
Cheers,
--Joe
Bill Shatzer
On Tue, 6 Feb 2001, David wrote:
-snips-
> As you know, an airship uses both aerostatic and aerodynamic
> lift in order to fly. The conventional cigar shaped hull acts
> as a crude airfoil and as such creates both lift and drag.
Actually, the traditional zeppelin-type airships used -negative-
aerodynmic lift. If the USS Los Angeles stalled, she stalled
-upwards-! The airship was trimmed for positive aerostatic lift
and the negative aerodynmic "lift" was used to maintain constant
altitude.
I leave it as an exercise to the reader to figure out just why this
scheme was utilized.
Cheers and all,
Ken Sykes
Snipperoo
> Maximum speed for USS Akron and Macon is given as 75.6 knots - which if my
> mental conversion calculator is working correctly, translates to a smidge
> under 87 mph.
>
> Cheers and all,
75.6 knots is 87.05740909mph. You can get a handy-dandy
converter proggy for all sorts of units here...
Quote:
Your one-stop source for all your conversion needs! Master Converter is
an extremely easy-to-use program that can convert over 700 units in 38
categories, with the ability to add your own units and categories.
Intuitive interface makes conversions quick and easy.
Tallyho!
KS
Yeff
Ken Sykes<kens...@epix.net> wrote in
rec.aviation.military:
>
> 75.6 knots is 87.05740909mph. You can get a handy-dandy
> converter proggy for all sorts of units here...
>
> http://www.savard.com/
"Convert" does the same thing and it's free.
http://www.joshmadison.com/software/convert/
-Jeff B.
yeff at erols dot com
Geoff May
news:3A82A5...@epix.net...
Actually, according to http://www.ycs.at/ycs/segeln/dictonary/s.htm you are
both correct. (The explanation in the web page is that the 'International
Nautical Mile' is 1,852m and the 'British Nautical Mile' is 1,853.18m. Trust
us Brits to do things differently ;).
P.S. the page is in German, but you can find the relevant entry under
'Seemeile - sea miles'.
MfG
Geoff.
David
"Bill Shatzer" <bsha...@OregonVOS.net> writes:
>David wrote:
>
> -snips-
>
> > As you know, an airship uses both aerostatic and aerodynamic
> > lift in order to fly. The conventional cigar shaped hull acts
> > as a crude airfoil and as such creates both lift and drag.
>
> Actually, the traditional zeppelin-type airships used -negative-
> aerodynmic lift. If the USS Los Angeles stalled, she stalled
> -upwards-! The airship was trimmed for positive aerostatic lift
> and the negative aerodynmic "lift" was used to maintain constant
> altitude.
This is very interesting Bill. Mine was a brief reply, and of course you're
right that airships often use
negative lift to adjust trim. Airship operation is a good deal more
complicated than most people imagine :)
The interactive trade off between aerodynamic lift and aerostatic lift is a
complex one, but what you say about Zeppelin LZ-126 or Los Angeles as she
was called the Americans is new to me.
Everything I have read or been told about the rigids, puts a good deal of
emphasis on the 'weighing off' process, prior to take off and landing. Put
briefly, this involved adjusting the ballast carried until the ship just
hung there - neither rising nor sinking. A combination of dropping ballast
and the aerodynamic lift caused by forward motion/ ground crew pushing
upwards, resulted in the ship rising upwards on take off. On landing the
ship was again weighed off so that she was responsive to the controls even
at low speed.
As far as I understand it, a ship like you describe that's trimmed to be
positively buoyant and relies on negative alpha to maintain altitude is
likely to give the pax and crew a very bumpy ride - especially so as fuel is
consumed and the ship becomes even more buoyant, requiring an increasingly
nose down attitude. As Dr Knut Eckener writes in his father's book, My
Zeppelins:
"...a 'light' ship flies badly and inefficiently. She is very unstable,
constantly pitching up and down, and makes a lot of trouble for the elevator
man."
I know the need to conserve helium with the US airships resulted in some
highly innovative design concepts such as water recovery systems to maintain
trim without valving the expensive He or flying at crazy angles. But are you
sure the LA or any US rigid was trimmed for positive aerostatic lift to any
significant degree ? If so how did the crew maintain trim as the ship became
lighter through fuel consumption or superheating ?
Best regards
David
Eugene Griessel
You are both partially incorrect. The nautical mile is that distance
that subtends an arc of 1 minute at the centre of the earth. And
because the earth is an oblate spheroid the nautical mile varies
between 1842.9 m at the equator and 1861.66 metres at the poles. The
lengths you are discussing are lengths of convenience. The average
nautical mile is approximately 1855.38 m which is known as the
geographical mile. For convenience sake the Brits took 6080 feet
(1853.1877m) as their standard and the International Nautical mile was
for some off reason set at 6076.1 feet (1852 m). The slight
differences are usually not important and if you do most of your
travelling in the 50 - 55 degree latitudes not important at all.
However if you are blundering around the equator you will notice the
difference, where you can be a few miles off in just a day's run
North-South/South-North.
Eugene L Griessel eug...@dynagen.co.za
Personal Page - www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Celestial Navigation - www.dynagen.co.za/eugene/where
Snakes - www.web.netactive.co.za/~sean
Gord Beaman
Bill Shatzer
On Thu, 8 Feb 2001, David wrote:
> "Bill Shatzer" <bsha...@OregonVOS.net> writes:
> >David wrote:
> > -snips-
> > > As you know, an airship uses both aerostatic and aerodynamic
> > > lift in order to fly. The conventional cigar shaped hull acts
> > > as a crude airfoil and as such creates both lift and drag.
> > Actually, the traditional zeppelin-type airships used -negative-
> > aerodynmic lift. If the USS Los Angeles stalled, she stalled
> > -upwards-! The airship was trimmed for positive aerostatic lift
> > and the negative aerodynmic "lift" was used to maintain constant
> > altitude.
> This is very interesting Bill. Mine was a brief reply, and of course you're
> right that airships often use
> negative lift to adjust trim. Airship operation is a good deal more
> complicated than most people imagine :)
> The interactive trade off between aerodynamic lift and aerostatic lift is a
> complex one, but what you say about Zeppelin LZ-126 or Los Angeles as she
> was called the Americans is new to me.
-snips-
> I know the need to conserve helium with the US airships resulted in some
> highly innovative design concepts such as water recovery systems to maintain
> trim without valving the expensive He or flying at crazy angles. But are you
> sure the LA or any US rigid was trimmed for positive aerostatic lift to any
> significant degree ? If so how did the crew maintain trim as the ship became
> lighter through fuel consumption or superheating ?
Well, I was -sure- I had read that in at least a couple places. But,
rechecking with the one reference I have in my home library ("Up Ship",
Robinson and Keller) discloses references to the US Navy airships flying
both heavy and light - with normal flight regimes between up to 11 degrees
nose up and up to 11 degrees nose down - generating both negative -and-
positive lift as the situation dictated. This was all directed, of
course, at the need to conserve helium which they Navy never had enough of
to operate more than a single airship at a time.
So, I stand partially corrected. And, you are absolutely correct that
airship operation was a -terribly- complicated undertaking.
Cheers and all,
Chris Morton
says...
>I recall reading somewhere that it's about 100kts. Beyond that, the energy
>required for propulsion (big blunt nose) is greater than for lift and
>thrust for fixed wings to carry a similar payload. Of course, the actual
>number varies with the size of the ship.
That of course raises the question of whether the nose actually HAS to be big
and blunt, or at least blunt.
Chris Morton
>I suspect that a limiting factor would be wind pressure against the
>nose of the airship. This is serious with current non-rigids, as their
I seem to recall a '50s era Navy experimental Navy airship with a
rigid/semi-rigid skin. I can't recall exactly what. Boron rings, a bell, but I
also vaguely recall boron being proposed as a FUEL for something too. The two
may or may not contradict each other.
I suspect that there'd be some kind of plastic or composite material that you
could use now.
Chris Morton
>As you know, an airship uses both aerostatic and aerodynamic lift in order
>to fly. The conventional cigar shaped hull acts as a crude airfoil and as
>such creates both lift and drag. Any aircraft is a trade-off between various
Would changing the envelope from a cigar shape to an airfoil (pumpkinseed) shape
affect this positively, negatively, or not at all?
Would shaping the envelope more or less like a flying wing overcome the inherent
problems of the cigar shape?
Bill Shatzer
At the cost of a different set of problems. The traditional cigar-shape
is the best compromise between lifting gas capacity and air resistance.
And the circular cross section of the traditional cigar-shape provides
maximum strength with minimum materials (i.e., weight).
Cheers and all,
David
>Chris Morton wrote:
>> "David" says...
>
> >As you know, an airship uses both aerostatic and aerodynamic lift in
order
> >to fly. The conventional cigar shaped hull acts as a crude airfoil and as
> >such creates both lift and drag. Any aircraft is a trade-off between
various
>
> Would changing the envelope from a cigar shape to an airfoil
(pumpkinseed)
> shape affect this positively, negatively, or not at all?
>
> Would shaping the envelope more or less like a flying wing overcome the
> inherent problems of the cigar shape?
Certainly, William Miller of Aereon believes the deltoid config. offers
advantages over the conventional cigar shape. He's not alone, interestingly
enough, the "2025" study by the Air Force University shows an Aereon ship on
its web site as a possible candidate for future heavy lift role.
A key modifier of any LTA design is the ease of control when the thing's on
the ground. A conventional ship can be quite a handful - though bow
thrusters and vectoring engines are making
the job of the ground crew much easier than their predecessors in the early
days of the airship.
Those who favour the more aerodynamic hull form ( such as a deltoid or
discoid) believe the ships would be less of a handful and be able to deal
with strong winds etc.
Some years ago, Roy P. Gibbens - a Lockheed engineer proposed a vehicle
called the SRA (Small Rigid Airship.) The model photograph I saw showed a
streamlined rectangle with a rigid, composite hull. It was an elegant
approach to the problem of keeping the mass of the stucture down whilst
maintaining strength - and of course the 20s/40s Tin Blimp or to give it its
correct title: the ZMC-2 had a metal monocoque hull.
FWIW, I'd say that as form follows function, it would be necessary to
consider a specific mission for any airship before decisions could be made
regarding its size and shape. In some circumstances, a hybrid vehicle such
as a deltoid may offer significant advantages over conventional designs.
Best
D
Phil Fraering
> In article <95ll8f$6nr$1...@nnrp1.deja.com>, Tony says...
>
> >I suspect that a limiting factor would be wind pressure against the
> >nose of the airship. This is serious with current non-rigids, as their
> I seem to recall a '50s era Navy experimental Navy airship with a
> rigid/semi-rigid skin. I can't recall exactly what. Boron rings, a
> bell, but I also vaguely recall boron being proposed as a FUEL for
> something too. The two may or may not contradict each other.
I think it was aluminum. It was in the 30's, and it was called the
ZMC-1.
I have a book with pictures of it somewhere around here.
--
Phil Fraering
p...@globalreach.net
And you can't have my shiny thing!
Phil Fraering
From: Phil Fraering <p...@globalreach.net>
Chris Morton <cmo...@newsguy.com> writes:
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