Can the Guy Next Door Build
His Own Cruise Missile? YES!
[and why that may not be the disaster you're expecting!]
- Part II [June 26, 2003] -
by Larry Cottrill, Editor, jetZILLA online magazine
_____________________________________________________
Note from the Author:
All opinions expressed in this series of articles are my own.
Mr Bruce Simpson was not consulted or interviewed in the
preparation of this article. He may, of course, respond publicly
or privately at any time, and is especially welcome to point out
anything he perceives to be in error in my description of this
project. This article is not meant to either endorse or
disparage Mr Bruce Simpson or his ‘D-I-Y Cruise Missile’ project,
and is solely intended to give the public needed information,
along with another viewpoint, on this topic.
_____________________________________________________
Recap of PART I
A few months ago, New Zealand pulsejet experimenter Bruce Simpson
set up a page on his popular Website purporting to show the
public how easy it would be for a normally skilled person with
malicious intent to build, from scratch, a small jet-powered
cruise missile at low cost and without arousing suspicion when
procuring the materials needed. While assuring the world that he
would not be revealing anything of a critical nature that would
be of use to a domestic terrorist in executing such a plan, the
project nonetheless quickly generated a high level of public
anxiety and a great deal of controversy. There seems to be little
doubt that Mr Simpson CAN accomplish his plan, given his high
level of technical skill in several critical areas. The question
most people are concerned with is whether the project should be
done. The question I would pose, however, is this: Even if Bruce
Simpson can succeed in this, does it really matter, in terms of
an actual terrorist threat of this kind that might materialize?
The purpose of this series is to try to come to a reasonable
answer to that question.
To recap what a terrorist would need to be able to do to bring
such a scheme to fruition - after the necessary planning and
technical design work, the plan would involve at least the
following tasks:
- Build a large, fast, rugged model airplane of sufficient
size to carry the deadly payload [and necessary fuel and
equipment] successfully to the desired target site
- Build a working jet engine out of new and/or scrap metal
[mostly some kind of sheet metal, assembled by welding]
- Build a guidance system [could be radio controlled, pre-
programmed dead reckoning with gyro guidance, GPS guidance,
or some combined system]
- Build a launching device to get the model up to speed
quickly when finally needed [this could supposedly consist
of a fast car, van or small truck]
- Perform extensive testing, without detection
- At the chosen moment in the wee hours, make a fast run down
the road and launch your device at the intended target;
then beat it back home and wait for the media coverage to
start
Bruce’s “construction diary” site page lays out his picture of
this process in better detail. [The link to this page on Bruce’s
site is listed at the bottom of this article.]
Bruce’s vision of how to accomplish the project is basically a
process of gluing together a great deal of easily available
‘over-the-counter’ technology, rather than coming up with a lot
of new and exotic stuff. This is the main reason that there is
little serious doubt that such a scheme is possible. Where I come
up with doubts about the viability of this threat has nothing to
do with what is possible, but rather with what is feasible. In
the area of pulsejet-powered missiles from the neighbor’s garage,
I will try to show that there is a great gulf between the two.
In Part I of this series, I made the following claims, all of
which are meant to cast some doubt on successful completion and
deployment by your neighborhood domestic terrorist:
1. Just because you can design a pulsejet doesn’t mean you can
build it
2. Just because you can design an airframe doesn’t mean you
can build it and get it flyable
3. Just because you’ve built the engine doesn’t mean you can
run it
4. Just because you can get it running doesn’t mean it will
perform well enough to deliver the payload
5. Just because you can get it running right doesn’t mean you can
launch it
6. Just because you can launch it doesn’t mean you can pilot it
7. Just because you can pilot it doesn’t mean a robotic system
can pilot it to the intended target point
Now it’s time to flesh out these claims so they can be heated in
the crucible of public opinion. You can let me know how much of
this looks real and how much you think is "fool's gold".
Just because you can design a pulsejet doesn’t mean you can
build it
When you study the possibilities for available engine designs to
use, you encounter a staggering variety, each claiming to be
successful, as constructed by the original designer. Basically,
there are two categories of designs to choose from – valved and
valveless pulsejets. This division is more than just technical;
it has a lot to do with construction methodology and run-time
performance.
There are few valved designs that work out well for amateur
builders with limited tooling. The best valved engines ever
created and successfully deployed are probably the very large
German Argus engine [used on the famous WWII “buzz bombs”] and
the somewhat more modern, but vastly smaller, DynaJet. While very
simple in mechanical principle, both involve very fine machining
of the front-end ‘valve plate’ to support the thin metal reeds
that enable them to work. Any lack of good fit or poor seating
between the valve plate and the reed valves results in degraded
performance and increased valve wear and breakage [and the
breaking of a valve can shut down the engine instantly!].
Technical improvements were made to the Argus design after the
war, but these did nothing to simplify manufacture of the
critical parts. Here’s an original Argus engine, partially cut
away to show interior details [photos by Dmitry Petrov]:
THE ORIGINAL
Mr Dmitry Petrov of Russia stands beside a captured Argus engine,
a relic of WWII German war technology. The Argus is probably the largest
pulsejet engine ever produced, and is certainly the first pulsejet design
ever put into mass production. This machine, designed by Paul Schmidt, is
the engine that propelled the infamous V-1 "buzz bomb" across the English
Channel to terrorize London and a few other target areas. Static thrust of
the Argus was approximately 550 pounds [275 force kg]. The noise of this
engine was unbelievable - and unmistakeable. This one has been heavily cut
away at the front end [at the bottom in this shot], to show the precisely
machined valve plate assembly [see detail shot, below].
Photo provided by, and property of, Dmitry Petrov
CLOSE UP AND PERSONAL
This closeup shot of the cut away front end of the Argus shows the back
side of the intricate valve plate, which in the Argus is a 'grid' made
from a precision casting that is machined to support both the thin spring
steel valves and the fuel injectors. Surprisingly, the reed valves
themselves are so small and numerous that they can't really be seen in
the photo, but three of the injectors are visible protruding from the
rear face of the grid. The steel tape Dmitry is using in these pictures
is metric, of course - each major division [between red marks] is 1/10 of
a metre, or just a hair under 4 inches.
Photo provided by, and property of, Dmitry Petrov
Valveless designs generally eliminate altogether the need for
fine quality machining. It is often said that these are the
simplest jet engines ever designed. What’s needed here are
skills in welding, sheet-metal forming and blacksmithing, but
these are needed [though to a lesser extent] in building a
valved engine, too. Basically, you’ve got to be able to put
together a sheet metal weldment of extremely light weight with
sufficient skill to ensure no weakness or leakage anywhere in the
structure. With some designs, such as the Lockwood [often called
the ‘Lockwood-Hiller’] type, just forming the tubular parts is a
major test of skill.
Mention of the Lockwood brings up the difficulty of scaling,
since the Lockwood is one of the few designs that has been
successfully worked out in medium-size versions that could be
used without re-scaling from something significantly larger or
smaller. Most published plans for pulsejet engines are for very
small engines of insufficient thrust for a terror weapon that
could really deliver something meaningful. Pulsejets are
notoriously hard to re-scale and get a successful engine,
although it is true that ‘scaling up’ [going larger] is somewhat
easier to handle than ‘scaling down’. Re-scaled engines often
have poor power for their size, or don’t start or run reliably.
These problems can be overcome, but not very easily. You either
need the ability to take a methematical approach to solving the
fluid dynamics problems involved in re-scaling, or work the
problems out experimentally through a lot of difficult tearing
apart, re-building and noisy test running [very hard to do
without detection, in most places].
Yes, there are plenty of amateur experimenters who possess these
skills, and the tools to go with them. However, this is just
the first phase of our domestic terrorist's cruise missile
project. A lot of other things have to fall into place beyond
this to move the project forward.
Just because you can design an airframe doesn’t mean you can
build it and get it flyable
At first thought, the airframe might seem to be the easy part of
the project - after all, we just need a big model airplane that's
capable of fairly high-speed operation [one figure Bruce has
mentioned is about 400 miles/hour, but this may be optimistic].
Again, the design and construction of a moderately high speed
airframe is found to be not quite as easy as 'scaling up' from
some design that is known to work as a 'speed trial' model plane.
With sport models, weight is usually the main problem - you want
to get a reasonably low wing loading [on the order of a few
ounces of aircraft weight per square foot of wing area] and a
moderate power loading [perhaps 1/2 HP per square foot] to go
along with it. A typical model might be a scale model of a WWII
fighter, for example. When it comes to designing record-breaking
speed models, however, weight is no longer the issue - drag at
the anticipated airspeed determines the design, almost
exclusively. That's why no one goes the route of scaling down a
full-size record racer, because you'll never get the desired
performance. Instead, the design becomes a kind of 'minimalist
sculpture' model -- getting the most power into the least surface
area possible, while packing enough 'beef' into the structure to
handle the considerable stresses of high flight speeds.
DRONING ON
A Russian export that isn't caviar - an Eniks target drone, from the 1990s. A target
drone is a small plane designed to be a moving target for fighter pilots, air defense
rocket launch teams, etc. They need to be cheap and fast, easy to see and hard to hit
[good evasive maneuvering is an important part of the training process, especially
when training fighter pilots]. This one is powered by a valveless engine that appears
to be based on the Lockwood design. I have no technical data, except that the
engine is supposed to supply about 34 lb [17 kg] thrust, which makes this a very small,
light craft [typical of target drones]; I would guess that a couple of guys could heft
this onto the launcher [shown in a separate photo, below]. Note the external mounting
of the engine above the fuselage, and the aluminum reflector to prevent heat-blistered
paint. Note also the relatively small wing and tail surfaces - minimal area for low drag
at full operational speed. A homebuilt missile might be similar in overall configuration
to this, but somewhat larger and almost certainly less colorful. This photo is from
an Eniks company marketing brochure.
It is easy to underestimate drag stresses when you first think
about high-speed flight. Aerodynamic drag is basically a
GEOMETRIC function of speed - to double the speed of a model, you
must overcome FOUR TIMES the drag; to triple the speed, you must
deal with NINE TIMES the drag; and so on. This is not just a
matter of power, but also structural strength. The wing of a slow
sport or stunt plane doesn't even need any special design for the
drag forces, but for a speed ship, the drag force on the wing is
one of the highest stresses in the entire plane.
For this very reason, both prop-driven and jet-propelled
U-control speed models are often simply carved out of solid pine
or basswood [an excellent illustration of the fact that weight is
not considered much of an issue]. But that's only a practical
construction scheme for the smallest models that can get by with
minimal control complexity. Construction of larger models would
need to involve advanced 'stressed skin' design concepts, and
would probably need to be built using some form of 'composite'
construction with 'fibreglas' or carbon-fiber reinforcing. This
type of construction requires a lot of experience to be effective
- it's not easy to get high strength where it's most needed in
the root section of a small wing, and the slightest structural
flaw can bring catastrophic failure in a sudden maneuver.
Another issue is the moving of the control surfaces. Every R/C
modeler knows how critical smoothness and reliability are, but in
the case of the missile, the speed and weight throw an extra
wrench into the works. In the case of small, slow models, there
is almost no significant aerodynamic force on the control
surfaces as they move further into the airstream; not so, when
you have a couple of hundred pounds of plane moving at 400 MPH.
The forces involved will be significant, and standard hobby
servos aren't going to deliver the power needed. Industrial
units are expensive [though possibly not enough to blow the
budget], and take a lot of electrical power to operate [which
means that large batteries will need to be carried on board].
Homebuilding small servos out of easily obtainable DC motors is
not out of the question, but demands yet one more skillset for our
terrorist. 'Aerodynamic balancing' of the controls can reduce
power demands to some degree, but this isn't feasible for ailerons
and wing flaps [if these controls turn out to be needed]. Also,
control hinges and linkages need to work smoothly under large
stresses, requiring critical design and accurate alignment.
Again, it's very doubtful that a beginner could get the job done
right. There are a lot of people who do have the experience to
accomplish the tasks needed, but this has to be on top of
building that perfect engine. And, the plane being built will
be moderately large and needs to be carefully concealed during
all this construction and finishing. But wait - there's more!
Just because you’ve built the engine doesn’t mean you can
run it
One more important thing that hobbyists have discovered about
pulsejets: No matter how good a builder you think you are, you
can’t get by without a lot of engine testing. Even with the
simplest pulsejet designs, there’s still plenty that can go
wrong. Even building from a proven design of the right size, you
still need to test, and you need to get your starting technique
perfected. You’re not going to do that on your first test run.
So, even if you have a “perfect” design and top-drawer quality
construction, you’re not going to get by without a considerable
amount of noisy testing, so you know what you’re doing at launch
time. Thrust measurement requires acquiring or building even
more equipment [at considerable expense, for a medium size engine
such as we're talking about here].
Once you start measuring thrust, you'll find that it's not quite
up to expectations. There is considerable 'tuning' to pulsejets
to get them really working right, even if your construction
skills are very high. Almost any pulsejet hobbyist will be glad
to tell you how easily an eagerly anticipated "first run" turned
into a research project that stretched out over weeks of spare
time. Getting a pulsejet engine right takes time, effort,
possibly considerable extra out-of-pocket expense, and a lot of
very noisy testing. Unless you're working with an exactly full-
sized model built from a carefully dimensioned plan of a totally
proven design, there's just no way around it. Our domestic
terrorist is going to need a test site pretty far off the beaten
path to get through this phase without arousing suspicion.
Just because you can get it running doesn’t mean it will
perform well enough to deliver the payload
Getting a good static run out of your engine and getting it to
carry you all the way from point A to point B are two somewhat
different things. Some pulsejet designs get weaker in thrust
and/or less fuel efficient when you introduce 'ram air' into the
equation. The Argus design, on the other hand, has been shown to
have actually performed better once it got moving, due to the
constricted opening of the front end, which creates a 'diffuser'
section [something like a ramjet front end] right in front of
the valve grid.
All jets are 'gas hogs' and pulsejets are poorer in fuel
efficiency than most other types, because of the absence of
compression during most of the combustion cycle. So, one of the
big problems for our missile designer is the need to carry a
heavy load of fuel [or on the other hand, to accept very limited
range]. The takeoff phase of the flight, where the machine is
struggling to gain speed, is particularly wasteful. [One way to
get around this is discussed later, when we talk about how to
launch the missile.]
Reliability of the engine is also an issue in getting your
deadly payload to the chosen target. All you need to stop a
running pulsejet is to make it miss one explosion, because the
energy of each explosion is used to pull in the next charge of
combustion air. This makes ultra-reliable fuel feed essential.
With liquid fuels, sloshing in the tank due to sharp maneuvers
[or even rough air along the route] could create enough of a
bubble in the fuel line to stop the engine cold. An explosion
behind the tailpipe [say from a small rocket in pursuit] can
halt engine operation, also. I'd speculate that the same thing
could be accomplished at the front end, though I'm by no means
certain of this.
Most fuel feed problems could be avoided with the use of a
pressurized gas or liquified gas fuel, such as propane, but it
would still require careful design and construction, including
an appropriate pressure reducing valve, at the cost of some
additional weight. In general, pressurized or liquified gas
fuel systems are thought to be bulkier and heavier than the
energy equivalent in combustible liquid fuel setups. In this
case however, that may not be true, since we'd almost certainly
need an electric pump to deliver liquid fuel [with a sizeable
and heavy battery to power it, of course], and a pressure
regulator to make sure the engine will keep running steadily.
There are only a couple of practical ways to test how your
engine will run in the air - test it in a wind tunnel [way too
expensive and complex to add to the project], or flight test it
[risky and hard to do while avoiding detection]. Of course,
our backyard terrorist might elect to just get it running the
best he can on the ground, and 'hope for the best' in flight;
that would be a poor choice, however, considering the
likelihood of failure or unacceptable performance.
Just because you can get it running right doesn’t mean you can
launch it
Contrary to popular belief, the most critical phase of any
airplane flight is not the landing, but the takeoff. This is
precisely where the vast majority of accidents happen, especially
in the case of light aircraft with non-professional pilots. It's
usually the best opportunity for engine failure, and the best
chance for stalling the airplane without sufficient room to
recover - and you can stall a plane with your engine delivering
full power! It's an interesting combination of dangers: you're
low and slow, but need all the power you can get to keep going -
and, you have no room to maneuver if you 'lose it' for even a
split second. And, all it takes to 'lose it' is a little too
much back pressure on the stick or tightening a turn a bit too
much in the climb!
But what you have going for you in a light plane at takeoff [that
we know our terrorist won't have in his missile at launch] is a
trained, thinking human being inside who can see, hear and feel
what the airplane is doing, and react properly. All three senses
may be involved in making a life-and-death decision, with only a
moment to react to what's happening. With luck, a human pilot can
save the situation, because the technique is practiced until it
becomes 'second nature' to react quickly and correctly [the key
word here being "correctly"].
At this point, someone should ask, "So, how is it that the German
V-1 crews were able to successfully launch several hundred such
missiles per day?" The secret is getting your missile up to MUCH
HIGHER THAN STALL SPEED at the launch -- and here is the one area
where weight really DOES work against you.
The Argus engine, like all well-developed pulsejets, had a quite
acceptable thrust-to-weight ratio; however, the V-1 missile as a
whole must have weighed at least a couple of metric tons [roughly
4000 lb], so the 550 lb thrust developed amounted to a fully
loaded aircraft T/W ratio of 1:7 or less - pathetic, even by WWII
standards. To allow the thing to take off under its own power
would have taken half a mile or more, with an unbelievable waste
of fuel in the first minutes. So, a launch scheme was designed
that was far superior to a normal takeoff run: booster rocket
launch.
The V-1 was positioned for launch at the end of a long 'launch
rail'. Under the surface of the rail, linked to the V-1 by a
simple lug that extended up into it, a solid-fuel rocket [the
so-called 'launch piston'] was triggered as soon as the Argus was
running full bore. Thus, the Argus and the booster 'piston' both
contributed to the launch thrust [much like the US Space Shuttle
and its solid boosters today]. The result was the V-1 getting
off the end of the rail with MUCH higher speed than the minimum
that would keep it in the air, virtually assuring a successful
beginning to its flight. The Eniks drone shown earlier uses a
clever portable launch rail, with a [presumably hydraulic]
cylinder and cable catapult arrangement taking the place of the
V-1's booster rocket system:
OUT TO LAUNCH
Another shot from the Eniks sales brochure - here, the Eniks drone is set up on
its portable launch rail, ready to go. This is an extremely short rail, mostly due to the
small size and weight of the drone; it also appears that there is a 'boost' catapult built
into this launcher, in the form of a hydraulic cylinder and a cable system that acts
as a velocity multiplier [looks like it might apply four times the cylinder's speed to the
drone at the first part of its forward slide up the rail]. The V-1, being much larger,
had permanent launch rails built, with rocket boosters to get the craft moving. Without
such an added boost, the takeoff run would be hopelessly long, with very high probability
of crashes after takeoff. The launcher shown here seems to be about the size of a large
boat trailer, and would probably cost far more to make than Bruce Simpson's entire
project budget!
Now, this is a wonderful method of getting our missile into the
air, except for one little thing: a launch rail with booster
could never be built for anything less than the cost of the
missile! For the V-1 or the Eniks drone, this makes sense because
multiple missiles will be launched from a single rail. But unless
our homegrown terrorist is independently wealthy [and can do all
this in an area as secluded as the Australian 'Outback'], this
method is out of the question. I agree with Bruce that the only
practical alternative is a launch from a fast land vehicle. I do
NOT agree, however, that this is very likely to work as
anticipated. Such a launch can be nothing better than a minimally
assisted takeoff.
Up to this point, I would have every confidence in Bruce's skills
to do whatever is needed to make the project work. Right here,
though, I think he's up against something fundamentally
different. Everything up to now has been build-and-test, go-at-
your-own-pace stuff. But at this point, we're talking about a
plane designed to cruise at 400 MPH lifting off at some humanly
attainable highway speed [granted this could be 100 MPH or more]
and controlling itself perfectly at the lowest speed it can fly,
for at least a second or two [long enough to gain some speed so
that it can safely pull up into a climbing attitude]. Everything
about this couple of seconds is critical -- the slightest excess
in nose-up attitude will stall it; all the control surfaces are
at minimum effectiveness, so responses will be sluggish; the
height above the roadway will provide mere feet in which to gain
any speed needed to recover. This exact scenario has cost untold
lives in normal category light aircraft, and this situation for
a truly high performance craft is far worse than for any single-
engine plane that gets off the ground at 50 or 60 MPH!
Is it possible to create control software that will handle the
takeoff so well that the potential problem never develops? Well,
of course, you can argue that anything is possible. What I know
is, IF the slightest thing goes wrong in those critical first
seconds, you've lost it, and you won't have the space and time
needed to get it back. If you're lucky when that happens, your
missile will be out in the clear in front of your truck before
it splats; but, since we know it's struggling along at minimum
speed, there's about as much chance of this as of winning the
Irish Sweepstakes. As an old pilot who remembers what these
stalls are like [and how easy it is to get into them], I'd
conservatively give this launch method about a 2 percent chance
of success. [And, I'll hope that Bruce has his fire retardant
suit and helmet on and in good condition, when he's speeding
down the highway on his launching run in that pickup!]
[There is a link to an excellent V-1 history site, with several
good V-1 launch photos, at the bottom of this article.]
Just because you can launch it doesn’t mean you can pilot it
Ask any R/C plane builder how often a new plane handles
perfectly the first time you take it out after building: never.
A new plane, even one kit-built and supposedly identical to a
thousand others, always has new quirks of its own. Usually,
these are minor issues of getting your plane 'in trim' [hard
to define, but one way to say it is, the ship will fly itself
straight and level without pilot intervention]. Sometimes,
though, major problems will be uncovered that need correction,
and on certain rare occasions, catastrophe strikes.
The point is, you have to fly the plane under the remote control
of an experienced human pilot to have any chance of knowing
whether all the systems work as planned. No modeler can ever
assume that everything will be perfect the first time out. For
our backyard terrorist, this means test flying a large, fast,
noisy aircraft without giving away the game.
Oh, and one more thing: He'll need to be, or have the help of,
an experienced high-performance R/C pilot to do this testing
successfully [i.e. with the airplane still in one piece
afterward]. Definitely not for novice flyers. The fact that good
control will need to be established immediately after a vehicle-
assisted launch at marginal flight speed only adds to the chance
of catastrophic failure. It is entirely likely that multiple
such test flights will be needed to know that everything works
reliably, all achieved without either public awareness or
private disaster.
Just because you can pilot it doesn’t mean a robotic system
can pilot it to the intended target point
From a purely technical standpoint, this may be the most
controversial part of the entire plan. I have no idea what
Bruce's software development skills are, but bringing this kind
of guidance and control system together would be a major
challenge for even an expert developer. There is a serious
question as to whether any over-the-counter GPS systems really
have the necessary resolution for such accurate targeting, and
apparently, device position is only updated once per second -
good enough for a hike through a national forest or even for a
sailing trip around the world, but pretty difficult to handle
properly in a device moving at almost 600 ft [about 180 m] per
second!
Guidance to a target is not just a matter of monitoring where you
are at a given moment. You need to process that information,
along with some number of previous positions [so you know your
actual direction!] and work this into a course correction. The
closer you get to the target point, the more rapid and accurate
such corrections will need to be [although you hope these will be
smaller and smaller corrections as you go].
Guidance to a precise target point is not simple; even the
military can't guarantee 100 percent accuracy or reliability, and
they've spent millions trying to perfect precision weapons
guidance technique. This is just one more example of something
that you'll never have working properly on your first attempt at
it. Admittedly, your initial testing could be done with small
models [even prop-driven ones] to wring out the most basic
problems. Eventually, though, you have to tie guidance in with
the actual control systems in your missile and make sure it all
works as planned.
Remember also that this is a three-dimensional guidance problem,
not just making sure you follow a path on a map. You want to take
advantage of 'tree top level' operation, but that means knowing
the terrain along the route and being able to program in the
altitudes you need everywhere along the path. At the end of your
flight, you want a smooth, fast descent into the target point
[for most kinds of potential targets, anyway]. Man-made obstacles
are a considerable hazard, and require constant updating of
stored data; in the rural Midwestern US, where I live, a new cell
phone tower 50 or 60 feet high seems to spring up out of nowhere
every two or three weeks!
This is a much too advanced topic for me to begin to appreciate
fully, but seems like a major problem area in the overall plan.
And again, we encounter the same recurring problem: there has to
be some practical testing in the final stages, without arousing
public interest. And, I'm not sure that this aspect of the
project will really ever be adequately proven [even by completing
a successful test!] using a path laid out in some sort of 'safe'
test flight range, since most meaningful targets for a real
terrorist wouldn't exist completely isolated, out in the middle
of nowhere.
(breathing a sigh of relief) - Conclusion to Part II –
I hope to have shown some of the problems our would-be pulsejet
missile terrorist will have to deal with in getting his evil
goal accomplished. The more I think about this, the less likely
it seems to me to come to reality as a one-man job; there's just
an awful lot to this, and I've just covered the basics - people
working in these technical specialties could point out a lot more
pitfalls than this [and correct a lot of things I've said in
blissful ignorance], I'm sure. This doesn't necessarily mean that
a man with the technical skills of Bruce Simpson can't bring the
project off; BUT, it does cast doubt on the reality of the threat
as perceived by the general public. I’ll try to zero in better on
the real nature of the threat in Part III. And in Part IV, I’ll
wrap up by talking about how I think the hobby pulsejet community
can relate in a meaningful, educational and non-threatening way
to the rest of the world.
Bruce Simpson’s ‘Construction Diary’ page is at:
www.interestingprojects.com/cruisemissile/diary.shtml
An excellent site on the German V-1 missile program, with an
impressive gallery of historic photographs, can be found at:
www.warbirdsresourcegroup.org/LRG/v1.html
-- End of Article Part II –-
____________________________________________________________
Larry Cottrill is Editor of jetZILLA online magazine and
 Director of Product Development and CEO of
Cottrill Cyclodyne Corporation of Mingo, Iowa, USA -
striving to create the world's smallest, safest and most
practical hobby jet engines.
You may contact me concerning this article at:
mailto:Editor@jetzilla.com
This article first appeared in jetZILLA ezine, Special Edition,
June 30, 2003. Permission is hereby granted by the author and
publisher to freely distribute this article, so long as you
agree to use the article in its entirety, without alterations
or additions, including this resource box.
Do you write articles? Click Here To Learn How You Can
MASSIVELY BOOST Your Exposure for FREE!
www.writers-viral-syndicator.com/Default.aspx?id=1156
The author is a member of the free Writer's Viral Syndicator
and sponsored by ad-CLiX Traffic Exchange Network
www.ad-CLiX.com
____________________________________________________________
Don’t miss the remaining articles in this series! Simply
subscribe [at no cost] to jetZILLA online magazine – just send
a BLANK email:
mailto:jetZILLA-subscribe@topica.com
Be sure to do this from the system where you want to receive
each email edition of jetZILLA. You should receive a validation
email immediately.
|
