Aim For The Moon - model rocket contest

Aim For The Moon - model rocket contest

Post by Jonathan Lee » Fri, 22 Jun 1990 15:55:10



Quote:

>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.

    What are "SETI dishes"?  If you're talking about the DSN antennae
at Goldstone, the VLA, or something else used for real science, I
don't think you could use them without holding a gun to somebody's
head.
--

    ``Are there any more questions, besides the ones from the
      liberal communists?''
        - George Uribe, natl. director of "Students For America"
 
 
 

Aim For The Moon - model rocket contest

Post by Karri Tapani Palovuo » Fri, 22 Jun 1990 17:08:44


Quote:

>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.

Wrong! (This is a very common mistake).

The escape velocity is not the velocity needed to escape!

A rocket that would climb 1 m/s would eventually reach the moon (yes, it
would take some time). Isn't this quite natural?

The escape velocity is the _theoretical_ (starting) velocity that would be
needed for a bullet to escape the gravity field generated by earth (solar
system, galaxy - there's many different 'escape velocities'). It is also the
speed gained by an object which is accelerated by corresponding gravity field
from infinitely far away.

Quote:
>Barry Moss

Karri

 
 
 

Aim For The Moon - model rocket contest

Post by Henry Spenc » Sat, 23 Jun 1990 00:24:45



Quote:
>The escape velocity is not the velocity needed to escape!

>A rocket that would climb 1 m/s would eventually reach the moon (yes, it
>would take some time). Isn't this quite natural?

>The escape velocity is the _theoretical_ (starting) velocity that would be
>needed for a bullet to escape the gravity field generated by earth...

However, for rockets with relatively brief burn times, escape velocity is
still a useful approximation to the truth.  The most efficient way to get
off Earth, were it not for the atmosphere, *would* be to accelerate to
escape velocity immediately.  Climbing under power wastes fuel fighting
gravity.  Given the atmosphere, alas, in practice it's necessary to climb
to quite high altitudes before getting into serious acceleration.  The
shuttle, for example, does almost all of its accelerating horizontally
at very high altitude -- to a sloppy first approximation, the basic job
of the SRBs is to get the rest of the shuttle up out of the atmosphere.
(In practice, one optimizes the trajectory for maximum results, and the
SRBs do end up contributing *some* horizontal velocity, but it's not
their primary job.)
--
As a user I'll take speed over|     Henry Spencer at U of Toronto Zoology

 
 
 

Aim For The Moon - model rocket contest

Post by A J Cunningh » Fri, 22 Jun 1990 21:52:57


        Given the current concern over the amount of debris already in
earth orbit shouldn't people be giving some consideration to what
happens to the payload after launch? Obviously the orbit will decay and
the payload will re-enter but after how long?
                Tony
--

        Yuppies think I'm a wino 'cos I seem to have no class,
        Girls think I'm ***ed 'cos I watch them as they pass.

 
 
 

Aim For The Moon - model rocket contest

Post by Derek Buza » Sat, 23 Jun 1990 02:46:45



#
#>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.

So get a boat and launch the thing from 201 miles offshore :-)

--
******************************************************************************
Derek Buzasi                     *    "History is made at night.
High Altitude Observatory        *     Character is what you are in the dark."

 
 
 

Aim For The Moon - model rocket contest

Post by Vincent Ca » Sat, 23 Jun 1990 04:01:08


Tony Cunningham:

Quote:
>    Given the current concern over the amount of debris already in
>earth orbit shouldn't people be giving some consideration to what
>happens to the payload after launch? Obviously the orbit will decay and
>the payload will re-enter but after how long?

I would not expect any of the rockets to go into orbit around the earth.  
They will either go up and back down, hit the moon, or escape the earth's
gravitational field.  The ones that come back down should do so after a
rather short time and so have much less chance of running into something
than the garbage that is orbiting for years.  

   -- Vince

 
 
 

Aim For The Moon - model rocket contest

Post by Phillip Harbis » Sat, 23 Jun 1990 01:50:31



Quote:

> Wright) writes:
> > 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?

It might be worth your trouble to contact the Consortium for Commercial
Development of Space at the University of Alabama in Huntsville.  They
get about $4 million a year from NASA to sponsor commercial launches.
Their latest was Consort 3, a successful flight which lofted a dozen
microgravity experiments to an altitude well over 100 miles.  They may
be interested in this "model rocket to the moon" idea, especially if
it only cost $10K-$50K.  I believe Deke Slayton's company charged them
about $1.5 million for the Consort 3 launch vehicle and services.

--
Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807

Bell: 205-883-4233, 205-880-8951

 
 
 

Aim For The Moon - model rocket contest

Post by Vincent Ca » Sat, 23 Jun 1990 04:26:15


I have an idea for raising money that I really like.  The idea is to make
a sort of "space-athon".  You get all of the people who are participating
to go around door to door getting people to pledge money for every rocket
that gets near the moon (within 100,000 miles).  People could pledge
10 cents per rocket or $1 per rocket or whatever.  If we could get the
equivalent of 10,000 people pledging $1 per rocket, then all of the rockets
that flew well should get enough prize money to more than pay back their
rocket club's expenses.

I would be willing to pledge at least $1 per rocket and I think that
with a little effort at least 9,999 other such people could be found.

This would just be for a "completion prize".  There would be other
prizes as well.  Also, people could still sponsor a rocket directly.

One nice thing about the completion prize is that different groups would be
able to work together and share ideas without worrying about loosing this
prize money.

What do you think?  Would you pay $1 per rocket that made it?
Send email pledges to:


   -- Vince

 
 
 

Aim For The Moon - model rocket contest

Post by David Palm » Sat, 23 Jun 1990 15:04:44


Three suggestions for hitting the moon:

        Handle aspect sensing (which way are we pointing?) with a sun
sensor.  Easy to make: just a cross of cardboard and 4 photodetectors
gives an error signal for adjusting the pointing.  Launch at dawn
to get the eastward component.  Launch at the right phase of the moon
so that the moon will be there when the rocket gets there.  Guidance
problem is solved.

        Launch from a weather balloon.  Going up even 50,000 feet
gets above a lot of the atmosphere.  For a small rocket, the balloon
doesn't have to be big.  Hang the rocket horizontally (tilting slightly upward)
and have it fire when the atmosphereic pressure is low enough AND
it is pointing in the right direction as determined
by the sun sensor.

        Launch from outside the US, maybe in international waters,
near the equator.  Saves a hell of a lot of money on legal fees.

        Good luck.

--
                David Palmer

                ...rutgers!cit-vax!gap.cco.caltech.edu!palmer
        I have the power to cloud men's minds -- or at least my own.

 
 
 

Aim For The Moon - model rocket contest

Post by Russ Ca » Sat, 23 Jun 1990 09:38:37


Quote:

>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.

No, not at all.  You have to consider that an eastward launch gets
a big advantage from the earth's spin velocity, while a vertical
launch gets nothing and a westward launch gets a penalty.  A 15
degree error is enough to make the difference between gaining
escape velocity and re-entering in a day.

Quote:
>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".

In that case, it is time to re-think the concept of servos.
Motors running gear trains are certainly too bulky and massy,
but what about piezoelectric plastic sandwiches pushing vanes
into the rocket exhaust (jetavators)?  Can they be built?
(By amateurs?  I am a double-E, not a mechanical engineer.)

Computers are light-weight, just order unpackaged semiconductor
dice or PLCC chips without the epoxy coating.  A couple lithium
watch batteries will run a 5V CMOS microprocessor.  I'm sure
that amateurs could assemble hardware from these (carefully).

The one element I see no simple way to shrink is the attitude
reference.  Unless...  Ha!  This may be it!

Does everyone remember the magnet-hovering-over-superconductor
photos we all saw when the high-temp superconducting ceramics
hit the press?  Okay, use tiny magnetic marbles as the gyros,
suspend them in nitrogen-chilled cups in a very small vacuum
chamber, and use coils to spin them up (with off-board power)
and read the signals from their spinning when they are off-axis.
Bingo.  There is your gyro table.  It will warm up and spin
down after a while, but after the boost phase is over you
don't care.  Boost phase will last a couple of minutes.

It might be doable for a mass budget of a few grams.  It will
need a lot of machining.  (Definitely too much for a $5,000
budget, but maybe not too many times more than that.)

[Please set your "Followup-to:" appropriately.]
--
  I am paid to write all of RSI's opinions.  Want me to write some for you?
(313) 662-9259        Forewarned is half an octopus.

 
 
 

Aim For The Moon - model rocket contest

Post by Henry Spenc » Sun, 24 Jun 1990 02:03:57


Quote:

>So get a boat and launch the thing from 201 miles offshore :-)

And then move to Liberia...  It doesn't matter if you launch the thing from
the Moon :-), if you're a US citizen, the US government claims jurisdiction.
--
As a user I'll take speed over|     Henry Spencer at U of Toronto Zoology

 
 
 

Aim For The Moon - model rocket contest

Post by Mark SOKOLOWS » Sun, 24 Jun 1990 02:37:50


        When somebody talked about the Scout's capacity in a recent post
(around 200 kg in LEO), I would like to show a calculation I did about
a manned spacecraft fitting in this weight category. First of all
it is possible to build a mercury like capsule having this mass, complete
with a thermal shield and controls. The simple requirements are for me
to go in there without a space-suit. For the other figures:

        - Me, 67 kg

        - The aluminium body, sustaining a 1 athm pressure
          (In practice, 0.3 athm. of pure O2), 100 kg

        - The attitude engines + main deceleration engine (Class N
          engine), 10 kg.

        - The survival unit (O2 for a few hours, climatization), 10 kg

        - A computer + interfaces, communication electronics, my
          walkman, 3 kg.

        - Parachute, 10 kg

        Of course, don't expect to much luxury aboard. 1/2 m^3 of
practical space (and inexistant bathroom). But I expect good sized
windows (a little like for gemini) to admire the view. And I won't be
afraid to go in it, even at the cost of being arrested afterwards (at
least in Canada) for sending a rocket of more than 500 grams into the
air! By the way, does anybody know where I can buy a Scout booster?
I'm starting the construction of my capsule at the end of this summer,
then I'll proceed to a space trip next year, after buying the booster
(ideally) or building one myself (Less preferable, since I don't have
much practical experience, but I'll do my best...). I guess this will
be a good start for Venus. Any comments???

Mark S.
-------

 
 
 

Aim For The Moon - model rocket contest

Post by Doug Mohn » Sun, 24 Jun 1990 05:54:35


Quote:

>    When somebody talked about the Scout's capacity in a recent post
>(around 200 kg in LEO), I would like to show a calculation I did about
>a manned spacecraft fitting in this weight category. First of all

[cut calculations...but 100KG for a capsule which will get you up and back
is a little bit thin. You'd want at least 200Kg as a safety margin. Of
course, you may not be afraid of re-entry so much...]

Quote:
>much practical experience, but I'll do my best...). I guess this will
>be a good start for Venus. Any comments???

Could you test the Clarke theory on vacuum while you're up there? There
are several stories (2001 among them) where his protagonists have to go
out the airlock without space suit, and I know many people on the net have
speculated as to what would happen if it was REALLY done. I think, Mark,
you would be the perfect candidate for such an experiment, and I'm sure
I could pass the hat to get you a flight on a Soyuz/Mir mission (NASA being
booked up for the next 5 years) so you can try it.

Upon your return, we can discuss Venus, hum?

 
 
 

Aim For The Moon - model rocket contest

Post by John DuBo » Sun, 24 Jun 1990 04:58:37


+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.

     I worked it out once; as I recall they're close to ZZ's.

        John DuBois

 
 
 

Aim For The Moon - model rocket contest

Post by Paul Ba » Wed, 27 Jun 1990 06:34:37


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).

The AmSat and other ham folks could likely design a suitable small
transmitter.  I'd suggest using UHF or VHF frequencies and
antennae build from "springy" metal (current hamsats use an old
measuring tape) perhaps from old watch/clock springs.  It really
doesn't take much power at all to achieve decent line-of-sight reception.
Using hams avoids FCC problems too.

Quote:
>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.

Nah.  Get hams involved - there are hams with significant investments
in equipment for LEO and moonbounce communications and access to more.

Quote:
>    Given the current concern over the amount of debris already in
>earth orbit shouldn't people be giving some consideration to what
>happens to the payload after launch? Obviously the orbit will decay and
>the payload will re-enter but after how long?

I think a LEO shot first is a good choice - and probably a 1 ounce
payload could be made with the right area:mass ratio to be short-lived.
A resonant 3-axis VHF set of dipoles might be just what's needed.

                        -Paul "Spice is the Variety of Life"