Aim For The Moon - model rocket contest

Aim For The Moon - model rocket contest

Post by Vincent Ca » Tue, 19 Jun 1990 06:55:15



1992 marks the 500 year anniversary of Columbus' trip to America.  It
would be fun to commemorate this with an "Aim for the moon" model rocket
contest.  The goal of the contest could be to get a small transmitter near
the moon as cheaply as possible (cost could be measured as total
newton-seconds of thrust for all stages).  The only restrictions would be
that only off the shelf "model rocket motors" could be used and that the
standard transmitter must be in the payload.  I think this limits people
to using "N" or smaller rockets.

It seems that using a small rocket to send a small transmitter to the
moon would be very possible.  It would take a rocket with a number of
stages starting with the larger size motors; however, I think you could do
it without going so far as making a 10 stage rocket that starts with
multiple "N"s.  To save you some arithmetic, let me point out that an "N"
has about 8,000 times the newton-seconds of an "A" motor.  The Isp on larger
"model" rocket motors is about the same as that used on "real" rockets.  
This means that, for each stage, the delta-Vs should be comparable to that
of large rockets with a comparable fraction of total weight as fuel -
except for air resistance. :-)   If you only want to lift a very small
payload it should be possible to do it with a reasonably small rocket.

Such an event would probably be well covered by the media.  This would be
good for rocket enthusiast in general and model rocket companies in
particular.  It could be a world wide contest.  Companies could probably
be convinced to donate prize money or sponsor a rocket.

There could be prizes (first, second, ...) in a number of different
categories.  One might be the "cheapest" rockets to get within 100,000
miles of the moon and go beyond the orbit of the moon.  Another might be
for the rockets that come the closest to the center of the side of the
moon facing us (crash landings ok).  Another might be for the shortest
trip time.  Another might be for the cheapest to escape the Earth's
gravitational field.

The rockets would be on the expensive side for model rockets (not for
space in general) so whole clubs would probably work together on one
entry to the contest.  My guess is that a rocket could be built for under
$5,000 in parts.  Once there is a formal contest, kids could get sponsors
and donations.  Many clubs would be able to raise that kind of money for
such a fun project.  The radio could be made to transmit the names of the
sponsors, designers, and builders.

If lots of us recommend the idea to clubs and rocket manufacturers this
might happen.  Please pass the idea on.

Such a contest would dramatically demonstrate the contrast between 1492
and 1992.  Back then many people thought the world was flat, today kids
all around the world can send rockets to the moon!!!!!!!!

    -- Vince

PS   I think the solar sail race to Mars is so neat that it would be fun
     to other things kind of like it.  Since entering this contest is
     relatively cheap, it could let many people get involved.

 
 
 

Aim For The Moon - model rocket contest

Post by kevin.w.mcki » Wed, 20 Jun 1990 03:41:42


Quote:

>1992 marks the 500 year anniversary of Columbus' trip to America.  It
>would be fun to commemorate this with an "Aim for the moon" model rocket
>contest.  The goal of the contest could be to get a small transmitter near
>the moon as cheaply as possible

Geezzz...couldn't we start with orbiting the earth?

Somebody want to volunteer to get the FAA clearance? :-)

Kevin

---------------------------------------------------------------------
Kevin McKiou                         UUCP:     att!ihlpy!kwm
NAR 51581

---------------------------------------------------------------------

 
 
 

Aim For The Moon - model rocket contest

Post by Patrick John Horg » Wed, 20 Jun 1990 10:40:08


WOW!  What an idea:)  Is this really feasible?  I would have thought
that the normal construction methods for model rockets would result in
the destruction of the model by the thrust of the early stages.  Does
anyone know the altitude record for model rockets using "normal", i.e.
<= D size engines?


 
 
 

Aim For The Moon - model rocket contest

Post by Ralph Re » Wed, 20 Jun 1990 10:54:05


Sounds like a great idea, but how big can a model get until it is no
longer a model?  I like the idea of just getting to the moon with
small rockets; perhaps a crash landing resulting in a small crater
would not require any radio at all (just send the rocket there by
itself?).

--
Ralph.
ARS: N6BNO
Compuserve: 72250,3521

 
 
 

Aim For The Moon - model rocket contest

Post by Edward V. Wrig » Thu, 21 Jun 1990 01:38:54


Quote:

>Somebody want to volunteer to get the FAA clearance? :-)

The FAA is not in charge of this.  You need a license from the
Dept. of Transporation's Office of Commercial Space Transporation.
The regulations are very complex, you will need a lawyer, and the
cost of the license will almost certainly exceed the $5000 budget
for this project.
 
 
 

Aim For The Moon - model rocket contest

Post by Vincent Ca » Thu, 21 Jun 1990 03:36:28


If you send $2.00 to:

Aerotech, Inc  
1955 South Palm St,  Suite 15
Los Vegas, NV 89104

  you can get a catalog of large engines.  They at least go
up to "M" and maybe "N".  Aerotech's phone numbers are (702) 641-2301
and (702) 641-2302.  An "M" sells for $995.  A "G" sells for $17
at a local store.  I do not have a catalog yet, but it seems prices
are going to be doing something like:    

A
B
C       $1
D       $2
E       $4
F       $8
G      $16
H      $32
I      $64
J     $128
K     $256
L     $512
M    $1024
N    $2048

The above estimated prices are probably not too far off for "G" and up.
There is some place that sells them for 30% off.

In case you did not already know, each letter has twice the newton-seconds
of the previous one.  A "G" has about 120 N-S of thrust and the fuel
weighs about 60 grams (I don't know the case weight).  While "A" to "D"
are rather small, there are large rocket motors for sale for reasonable
prices.  Note that if you had one stage for each of the above motors
your total motor cost would be about $4,096.  Your delta-V should be
more than enough to get escape velocity if your payload is about the
weight of an "A".   Note that the transmitter may transmit a high
powered burst for a very short time, say 1/100 of second every 100
seconds, so as not to use very much power.  With a 90 foot dish on the
ground we should be able to pick up such a signal.  I think us little
guys could really make rockets to send things into space!!!!!!!!!!!

It seems you may have to be a member of Tripoli before you can buy
large engines (at least from some places).  Tripoli's address is:

Tripoli Rocketry Association Inc.
P.O. Box 87669                                    
San Diego, CA  92138-7669                        

The important point is that a small rocket gets the same delta-V for
the same payload/fuel ratio of a large rocket if it has the same Isp
and these "little" rockets have about the same Isp.  This means that
ROCKETS SCALE DOWN VERY WELL except for air resistance and control.  
If all you want to do is go up, control may not be much of a problem
(could fins and spinning be enough?).  Getting into orbit would be
hard since you would need good control.  The higher you get the less
of a problem air resistance will be.  Smaller rockets do have smaller
diameters, but air resistance does cause lower payload/fuel ratios for
small rockets getting the same delta-V as larger ones.

   -- Vince

 
 
 

Aim For The Moon - model rocket contest

Post by Vincent Ca » Thu, 21 Jun 1990 11:55:49


Patrick John Horgan

Quote:
>WOW!  What an idea:)  Is this really feasible?  I would have thought
>that the normal construction methods for model rockets would result in
>the destruction of the model by the thrust of the early stages.  

Feasible really boils down to, "How much money can you spend?".  If you
have $30,000 I am rather sure it is feasible.  If you have $5,000,
I think it is.  If you have $2,000, maybe.  A big part of the contest
would be designing for low cost.

I don't think the high Gs would be all that much more than model
rockets are used to.  There is no real reason that the acceleration
from the lower stages would be any higher than the upper stages.  If
each stage is half the size of the previous one (with the payload
equal to the weight of the last stage), each motor is pushing on upper
stages about equal to its starting weight (modulo cases).  Thus each
stage could add about the same delta-V with about the same acceleration.


Quote:
>Five years ago, the MIT ...

>The goal was to put 1 kilogram in orbit.  We learned a lot, especially that
>things like guidance systems do not shrink nearly as easily as fuel tanks.

>The SCOUT Planning Guide says that a Scout booster (21500 kg GLOW) can put
>a 250 kg payload into a 200 Km orbit, which is about as low as you can get
>and still call it an orbit.  Linear scaling says that an 86 kg model rocket
>could put 1 kg into the same orbit.  Unfortunately, the scaling ain't
>linear!

If we only put 1 oz or 100 grams into space it would still be loads of fun.
Only :-) control, the motor cases, and air resistance are not linear.
If large rockets cost about $10,000/lb to send stuff into GEO then getting
1 oz near the moon for $5,000 still leaves a factor of 8 for non-linear
scaling.  You just aren't thinking small enough!!!!  

Quote:
>Scout is about as simple a rocket as you can get.  The stages are all solid
>fuel, more or less the same as high-class model rocket engines.  The
>guidance system is incredibly simple: a roll-yaw stabilization gyro, a
>pitch stabilization gyro, and a timer.  The timer kicks the pitch gyro
>occasionally to bend the trajectory downrange.  Even though it's 1960
>technology, you're not going to build a system much lighter than that
>with microprocessors.  The fourth (and optional fifth) stages are spun up
>pointing in the right direction, but otherwise unguided.

What if we just use fins on the first stage or two to get going and
spin things up, and then just use the spin for all of the later stages?  
No control computer or servos at all!!!!  If we can keep within 15 degrees
of vertical we should be just fine, assuming the goal is just to get up.
It would be just about as fun to fly past the moon 100,000 miles away
as it would be to hit the moon.  Also, remember that the moon will pull
things towards it.

Getting into orbit would need active control and so ruin the scaling.
You would need lots of servos and a computer.  I don't think you need this
just to "Aim For The Moon".

   -- Vince

 
 
 

Aim For The Moon - model rocket contest

Post by Ronald G Minni » Fri, 22 Jun 1990 03:14:09



Quote:
>The regulations are very complex, you will need a lawyer, and the
>cost of the license will almost certainly exceed the $5000 budget
>for this project.

OK let's get uncle sugar to pay the cost. What are senators for?
I am actually dead serious, if there were an amateur organization
with this sort of activity in mind then the govt. might be persuaded to
make life much easier for them. Look at what the FCC did for amateur
radio types all those years ago.
   Anybody in the DC area doing this stuff?
ron

--
Grad student, ca 1976: Gosh, the v6 kernel is < 64K! Compare it to that
                       OS/MVS hog at 400K!
Grad student, ca 1986: Look at all the good stuff in Gnu Emacs for only 600K!

 
 
 

Aim For The Moon - model rocket contest

Post by bil » Fri, 22 Jun 1990 04:34:26



Quote:
}>Somebody want to volunteer to get the FAA clearance? :-)
}The FAA is not in charge of this.  You need a license from the Dept. of
}Transporation's Office of Commercial Space Transporation. The regulations
}are very complex, you will need a lawyer, and the cost of the license will
}almost certainly exceed the $5000 budget for this project.

Perhaps some other country would be willing to host the shoot, without
all the legal complications.

Mexico's first space launch, perhaps??

--

 
 
 

Aim For The Moon - model rocket contest

Post by mos » Fri, 22 Jun 1990 04:34:37


Quote:

>I think us little
>guys could really make rockets to send things into space!!!!!!!!!!!

Hmmm....  Let's see.  Escape velocity is about 7 miles/sec = 25,000 m.p.h.
Now while this space rocket wouldn't reach top velocity until the final stage
burned, it seams to me that the friction associated with Mach 10+ in the
upper atmosphere would turn this rocket into a crispy critter. Not to
mention the structural stresses of super-sonic speeds on a balsa and paper
model.  Of course the rocket could be made from light weight metals but then
its no longer a *model* rocket.  At this point we're starting to enter
amatuer rocketry (no flames please - I have nothing against properly
supervised amatuer rocketry).

Still, the idea of a non-governmental, non-commercial hobbyist space launch
is quite interesting.  This could probably catch the attention of some media
types and provide some positive press for model rocketry, esp. if the launch
were combined with another rocketry event.

Barry Moss

 
 
 

Aim For The Moon - model rocket contest

Post by Vincent Ca » Fri, 22 Jun 1990 06:24:53


Lawrence Curcio:

Quote:
>Assumptions:
>[...]
>Rocket is composed of class N clusters, because Class N engines
>have the best mass ratios

>Top stage is one N engine

>Each stage carries stages above it that total half of the mass of
>the current stage => mass ratio of each stage is 2.0
>[...]
>ENGINES REQUIRED= 6561
>MINIMUM COST IN $ 8529300   (That's $8,529,300.00)

>Any calculational errors? Please correct and repost.

You do NOT want the total weight of all of the above stages
to be half the current stage weight for model rockets where
the current stage case weight is significant.

You do NOT want to have your smallest stage be made from the largest
and most expensive rocket engine that you can buy.  The goal is to
end up with 1 oz way up there, not kilograms (the last case in your
design weighs 2 kg!!).  We are not after efficiency, only low cost.
If your smallest engine costs $2,000 and each larger stage costs more than
a factor of two more than the previous (your design) your total cost
will be around 2,000 times as much as if your smallest stage cost
only $1.00.   The whole point of the idea is to use small cheap motors
to send up a very very small payload!!

Some real prices from Vulcan Systems Inc (719) 633-9889:

Motor  Thrust  Length     Cost
--------------------------------
E       40 ns   3.0  in     $8
F       80 ns   4.5  in    $10
G      130 ns   6.0  in    $15
H      320 ns   7.25 in    $32.5
I      640 ns  11.25 in    $60
J     1280 ns  11.25 in   $110
K     2560 ns  22.0  in   $210

They did not give me the weights of the motors.

Imagine a multistage rocket made using one motor from each motor type.
If each motor were only 1/2 fuel (the other half case) each stage
would act like a single stage rocket with 25% of its weight as fuel.
By my calculations a single stage rocket with an Isp of 230 that is
25% fuel will get a delta-V of 1,500 MPH.  In practice all motors from
G to N are over 1/2 fuel so they will do better than this.  So it
should be possible to make a rocket with less than 14 stages (A to N)
that gets the needed delta-V.  If you launch from a balloon you could
start at 100,000 feet and avoid most of the air.  It now looks like you
could buy one motor of every type up to "N" for under $3,000.

   -- Vince

PS  Has anyone calculated what a space shuttle solid rocket booster is on
    the "model" rocket scale?  Seems like it will be something like 100 "Z"s
    but I don't have the data for the SRBs.

 
 
 

Aim For The Moon - model rocket contest

Post by Vincent Ca » Fri, 22 Jun 1990 07:00:21


I just talked with someone at Vulcan Systems Inc.  He told me that
their K500 weighs about 3.5 pounds with the fuel being 2.5 pounds of
that.  He said that the Isp was about 225.  I asked if by paying
more I could get lighter cases and he said, "Sure if it is large
order".   He could replace the 16 oz case with a 4.5 oz case.  
The 4.5 oz case was about $100.  A 2.75 lb rocket with a 0.25 lb
case would be far better than a 3.5 lb rocket with the same thrust,
especially when used as an upper stage.  The extra cost would be well
worth it.

I told him about wanting to send something into space and he said
they were building a 60 inch rocket motor for somebody who was sending
something into orbit.  I was surprised and he said that they made
stuff for the military and could make any size.  I said, "So I
could just order a "Q" and you would make it?"  He said, "Sure."

With very light cases we should be able to get about a 3,000 MPH delta-V
from each stage (using an engine of half the size in each higher stage).  
Thus a total of 8 stages or so should do it.

I AM SURE WE CAN SEND LITTLE ROCKETS INTO SPACE!!!!!!!!!!!!!!!!!!!!

  -- Vince

 
 
 

Aim For The Moon - model rocket contest

Post by Lawrence Curc » Fri, 22 Jun 1990 11:52:15


Simmer down there, Vince! If the discussion is going to make
sense, we have to start doing some numbers, and that means we
have to start making some assumptions and modifying them. Nobody
else was doing this, so I thought I would. I assumed you would be
using Aerotech class N's because (1) I have data on only Aerotech
motors, and (2) I figured you wanted the highest available mass
ratio. The larger the diameter, the higher the mass ratio. The
class N has a mass ratio of four. The engine you described has a
mass ratio of 3.5. If you have smaller mass ratios, you are going
to have to have more stages. More stages means bigger lower
stages. There is a trade-off. (BTW the class N costs $1300, not
$3000.)

The business of upper stages weighing half of the current stage -
that was pulled out of the air. There is an optimization problem
here. Again, let's do NUMBERS. Show us a better configuration.

I forget what a reasonable orbital velocity is - 4 mile/second?
If that is true, then orbit can be achieved in 5 stages - or
fewer if you can have a bigger engine made. Problem is, why send
up only one ounce? How will you know it got anywhere? It will be
like any other rocket that goes out of sight, only bigger and
more expensive. This isn't a rhetorical question. As I say, I'm
up for something, but a good thing deserves up front
consideration. Lets do some. The group seems like a good forum.

-Larry Curcio

 
 
 

Aim For The Moon - model rocket contest

Post by Henry Spenc » Fri, 22 Jun 1990 13:03:38


Quote:

>Sounds like a great idea, but how big can a model get until it is no
>longer a model? ...

I believe the US regulations are set up so that any rocket capable of
going above 100km falls under OCST jurisdiction, i.e. it is a full-fledged
launcher requiring full paperwork.  The rules don't say "100km" for silly
reasons of interagency politics, but they set restrictions on total impulse
and the like that supposedly amount to a 100km limit in practice.

Under that there is a large gray area where OCST does not get involved,
but the FAA and explosives laws do; I don't know much about the situation
there.

To truly qualify as a model rocket, it has to pretty much stay within
the orthodox model-rocket rules and size limits.
--
As a user I'll take speed over|     Henry Spencer at U of Toronto Zoology

 
 
 

Aim For The Moon - model rocket contest

Post by Vincent Ca » Fri, 22 Jun 1990 15:09:14


Lawrence Curcio:

Quote:
>If you have smaller mass ratios, you are going
>to have to have more stages. More stages means bigger lower
>stages. There is a trade-off.

I can make a 12 stage rocket where the lowest stage is an "N" that has
the same delta-V as an 8 stage rocket that you make where the top stage
in an "N".  Your lower stage is far far larger than mine.

Quote:
>(BTW the class N costs $1300, not $3000.)

The $3,000 was for one of every motor from "A" to an "N".

Quote:
>Problem is, why send up only one ounce?  How will you know it
>got anywhere?

The 1 oz payload is a radio transmitter that sends out a burst every
now and then (say 1/100th of a second every 100 seconds).  The burst
can be very high power while the average power usage is very low.
Using something like this I think we can get by without having a
directional antenna on the rocket and using only a lithium battery
(solar cells would be fun too).  

One thing the contest organizers would have to provide would be a number
of large ground dishes.  For low altitudes we should be able to get
by with a small portable dish.  After it has gone up 100 miles we could
follow it with one or more of the very large SETI dishes (like 90+ foot
diameter).  We do, of course, need to talk some SETI people into this
but I think that could be done.

Anyone interested in helping to organize an "Aim For The Moon" contest?

   -- Vince