Students questions to model rocket designs

Students questions to model rocket designs

Post by Maurice J. Lepin » Thu, 26 Oct 1995 04:00:00



I am a Technoogy Education Teacher with very little experience with
Model Rocketry. I have approximently 80 - 9th grade students designing,
drawing plans and then constructing scratch built model rockets. They
are very into this project, however they have asked some very good
questions that I do not fell qualified or comfortable to answer. So here
it goes:

1. Is there on optimum length for a 1" diameter rocket with a B-6-4
engine?

2. In relation to the rocket's length. How tall should the tailfins be?
How far out from the fuselage should they come?

3. In relation to the tail fins. How should the height compare to the
width?

 
 
 

Students questions to model rocket designs

Post by Maurice J. Lepin » Thu, 26 Oct 1995 04:00:00


I am a Technoogy Education Teacher with very little experience with
Model Rocketry. I have approximently 80 - 9th grade students designing,
drawing plans and then constructing scratch built model rockets. They
are very into this project, however they have asked some very good
questions that I do not fell qualified or comfortable to answer. So here
it goes:

1. Is there on optimum length for a 1" diameter rocket with a B-6-4
engine?

2. In relation to the rocket's length. How tall should the tailfins be?
How far out from the fuselage should they come?

3. In relation to the tail fins. How should the height compare to the
width?

 
 
 

Students questions to model rocket designs

Post by Konrad Hambri » Sun, 29 Oct 1995 04:00:00



Quote:

>In Stine's "Handbook of Model Rocketry", in the chapter on model rocket
>aerodynamics, he claims that the two best fin shapes are elliptical and
>"clipped delta", with the clipped delta being a lot easier to work with.
>He then has some numbers for an optimized clipped delta fin expressed in
>terms of the rocket diameter:

>                  |<-Ctip->|
>                      __________  _
>             /         |  ^         Ctip = D        (tip chord)  
>            /          |  |         CRoot = 2D      (root chord)
>           /           |            S = 2D          (span)      
>          /            |  S                                      
>         /             |            O = 20 degrees.
>     |O /              |  |
>     | /               |  V
>----------------------------  -
>           |<-----Croot--->|  ^
>                              D
>----------------------------  v

Nice drawing, Bill.

More from _The_Handbook_of_Model_Rocketry_:

Back in chapter 9 -- Stability ( my favorite chapter ;-), pp 145,
GHS quotes Mandell, et al. from _Topics_in_Advanced_Model_Rocketry_
saying:

   1.  Maintain a length-to-diameter ratio of 10:1 or
       more to provide adequate damping.

   2.  Maintain a static stability margin between 1
       and 2 calibers to prevent overdamping but don't
       go below 1 caliber.

   etc.

Just my $0.02 ;-)

-- kjh
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Students questions to model rocket designs

Post by Willia » Sun, 29 Oct 1995 04:00:00


    1. Is there on optimum length for a 1" diameter rocket with a B-6-4
    engine?

    2. In relation to the rocket's length. How tall should the tailfins be?
    How far out from the fuselage should they come?

    3. In relation to the tail fins. How should the height compare to the
    width?

In Stine's "Handbook of Model Rocketry", in the chapter on model rocket
aerodynamics, he claims that the two best fin shapes are elliptical and
"clipped delta", with the clipped delta being a lot easier to work with.
He then has some numbers for an optimized clipped delta fin expressed in
terms of the rocket diameter:

                  |<-Ctip->|
                  __________  _
                 /         |  ^         Ctip = D        (tip chord)  
                /          |  |         CRoot = 2D      (root chord)
               /           |            S = 2D          (span)      
              /            |  S                                      
             /             |            O = 20 degrees.
         |O /              |  |
         | /               |  V
----------------------------  -
           |<-----Croot--->|  ^
                              D
----------------------------  v

If you start with the optimized fins, and then calculate the minimum
length that gives a stable rocket, your rocket should be pretty optimal.
(as a starting point a length of 10*D or so seems pretty standard.)

BillW

 
 
 

Students questions to model rocket designs

Post by Helen Rapo » Mon, 30 Oct 1995 03:00:00



Quote:

>I am a Technoogy Education Teacher with very little experience with
>Model Rocketry. I have approximently 80 - 9th grade students designing,
>drawing plans and then constructing scratch built model rockets. They
>are very into this project, however they have asked some very good
>questions that I do not fell qualified or comfortable to answer. So here
>it goes:

>1. Is there on optimum length for a 1" diameter rocket with a B-6-4
>engine?

************
To do what?  Highest attitude, longest flight time by recovery
by parachute or streamer, closest distance between the launching
pad and the landing point or some other type of activity that
you have planned for these flights.
Quote:

>2. In relation to the rocket's length. How tall should the tailfins be?
>How far out from the fuselage should they come?

>3. In relation to the tail fins. How should the height compare to the
>width?

**********
There was section on this in the 1994 Estes catalog.  According
to it the size of the fins were a relation to the width of the
body tube.  It was recommend that the root edge (edge connected
to the body tube) side be 2 times the diameter of the body tube,
the opposite side of root edge be 1 diameter and the height
be 1.5 times the diameter.

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Students questions to model rocket designs

Post by AVin » Fri, 03 Nov 1995 04:00:00


Another $.02,

Get Stines book! it is really good. He goes over the basics and explains
things in a very clear manor. Be sure to ask yourself 'what do you really
want the rocket to do?'. I would guess that a bunch of 9th graders would
be more interested in the "Coolness" thing (look for an upcoming article
in rocket mags) than anything. If that id the case, they can get real
creative and have lots of fun. Again Stines book or the Estes catalog will
get you in the neighborhood.

Thanks Harry Stine for your contributions to the modeling community!!!