Kitbashing a "Prowler" into a "Growler"...

Kitbashing a "Prowler" into a "Growler"...

Post by nojun » Fri, 12 Jun 1998 04:00:00



I recently bought an Estes "Prowler" in a local hobby shop, after
looking at it and deciding that it would be an excellent candidate for
some modifications.  Here's a brief summary about how to turn your
Prowler into a Growler.  (What *were* they thinking...B4-2, B6-2, C5-3,
and C6-3?  Nahhh...this seems more like a D15 through F39 type of rocket
to me!)

First, some background and kit info...

The Estes Prowler is a new (1998) kit, originally designed for 18mm
motors.  As kitted it was 40.5 inches long, with a listed weight of 4.2
oz. (120g), and comes with a 24" plastic parasheet (standard Estes
issue).  This one uses through-the-wall, to-the-motormount fin mounting.
It comes with glow-in-the-dark stick-on decals, and warnings that these
are just for display purposes, and not to launch it at night due to the
danger of tripping over stuff and hurting yourself in the dark.  (I
sometimes wish that our society hadn't become so litigious, and we could
just let Darwin do his job on those that would eventually be culled from
the breeding pool.)

The changes I decided to make were...

Since the kit was already using TTW fins, I figured it would be strong
enough to make good use of a 24mm motor mount.  I also decided to modify
the motor mount to allow use of the Aerotech 24mm RMS system.  The other
major change was to use the Anti-Zipper design from the recent Sport
Rocketry article.  I also used the transition piece that came attached
to the nosecone as a boattail.  This slightly changes the lines of the
rocket, giving it a "faster" look, and should help it achieve somewhat
higher altitudes.

Construction hints, tips, and gotchas...

I wound up using almost all of the kit parts that were supplied, with
the exception of the original motor mount tube, centering rings, and
black retaining ring.  These can be used in other scratchbuilds, so
there was essentially no waste.  (Actually, since I used the adapter
piece that came attached to the nosecone as a boattail for my modified
kit, I "wasted" one less part than Estes wanted me to.)

The first step in construction is the motor mount.  I just used a piece
of 24mm Estes tube in place of the supplied motor tube.  I also used a
large green thrust block from an old kit as a thrust ring.  I used a
Dremel wheel to grind off a portion (about 1/2 of the original length)
of the front of the motor hook so that I could place a 24mm RMS casing
in the tube.  I used double centering rings (2050 thin-stock rings,
glued together to make them double thickness...4 total used, 2 in front
and 2 at the rear).  Measure carefully; you'll want the front and rear
edges of the fin tabs to *just* touch the centering rings, to give some
additional gluing surfaces and adding some more rigidity to the rear of
the rocket.

The motor mount was moved rearward about 1-1/2" so that the tube would
extend to be even with the rear of the boattail section.  Some slight
"machining" was done on the plastic to allow the motor hook to work
within the boattail.  (I just needed to "thin" the plastic; there's no
gap in the line of the boattail as viewed from the side...the motor hook
stays inside the diameter of the end of the boattail.) A small centering
ring was added inside the rear portion of the boattail to act as an
additional support and gluing surface for the motor mount.  

System3 epoxy was used throughout the construction.  Silica thickener
and phenolic microballoons were added as necessary for the various
functions (adhesive, fillet, etc).  

The fins were made of the hardest balsa I have ever encountered.  Since
I was using a larger motor tube, I had to remove some stock from the
mounting tab to get the fins to sit flush against the body tube.  A
Dremel reinforced cutoff wheel was used, but it was really slow going,
and there was some scorching of the wood as it was being cut.  As I
said, that was some *hard* balsa!  Leading and trailing edges were
tapered with a sanding drum, and the tips were left squared off.

For the zipper-proof mods, only the front two body tube sections were
glued together.  The rear tube section gained a 1/4" thick basswood
baffle plate glued into the coupler, with multiple 1/4" holes drilled
through it.  A***eye was placed in the middle and epoxied in place.
One half of a "ChoreBoy" sc*** was pushed through the motor mount
tube to the area between the front of the motor mount tube and the
baffle plate.  This can easily be removed for replacement when needed
from the tail end of the rocket.

All that's left now is the finishing steps; construction is done.

The fins and body spiral are going to be coated with thinned Elmer's
Fill-n-Finish, primed, and painted with Rust-Oleum Metallic paints.  A
clearcoat over the paint and it should look *great*.  Even with the
rearward-moved CG (larger motor mount, shifted back for the boattail,
and the baffle system) the kit should require no noseweight, since it's
a nice, long, overstable Estes design at its heart.

I'm looking forward to finishing this one and getting a decent-sized
motor into it.  It's a clean design, and with the boattail and other
mods it should be interesting to fly.

--
Mike
NAR #70953 - Sr./Insured ~ SeaNAR - The Seattle Area NAR Section #568
NO Junk Email, please! Real email to: amphoto [at] wolfenet [dot] com.
<WARNING: Do not look into laser beam with remaining eye!>

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by PeteAlw » Sat, 13 Jun 1998 04:00:00


Quote:

>I recently bought an Estes "Prowler" in a local hobby shop, after
>looking at it and deciding that it would be an excellent candidate for
>some modifications.  Here's a brief summary about how to turn your
>Prowler into a Growler.  (What *were* they thinking...B4-2, B6-2, C5-3,
>and C6-3?  Nahhh...this seems more like a D15 through F39 type of rocket
>to me!)

You know, If I were going to kitbash this one, I'd turn it scale, but if I
*were* inclined to increast the impulse, It just cries out to be made into a 3
x 18mm engine cluster.  Line up the three BT-20's betwen the fin slots, and the
fins can be reinforced between tubes.

Peter "Make it into a Doorknob, Pencil, S-520, Sandhawk, Viking, D-Region
Tomahawk, or Aries" Alway

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Armando Flore » Sat, 13 Jun 1998 04:00:00


If you are limited to a typical playground field like I am, the original size and
construction is perfect with C6-3's and C5-3's.  It gives the little ones a chance
to see the apogee and deployment of the chute (I modified the engine mount with
Kevlar and put a nice spill hole on the chute).  Lots of ooohhhss and aaahhhhhs
from the little tykes.

However, if you want to put some spark, put a D engine mount (you can always go
back to B's and C's) and watch the action.  My next Prowler/Growler I plan to build

will have a 3 18mm cluster engine mount.  I would like to see how it will operate
with 2 C6-0's and 1 C5-3.  EOM

Regards
Armando Flores
Certifiable BAR
KB5DTU
EOT

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Robert DeHat » Sat, 13 Jun 1998 04:00:00


Quote:

> I recently bought an Estes "Prowler" in a local hobby shop, after
<snip>
> For the zipper-proof mods, only the front two body tube sections were
> glued together.

<snip

What did you do for the zipper-proof mod?

Just wondering.

RDH8

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Tim » Sat, 13 Jun 1998 04:00:00


Quote:

> However, if you want to put some spark, put a D engine mount (you can always go
> back to B's and C's) and watch the action.  My next Prowler/Growler I plan to build

> will have a 3 18mm cluster engine mount.  I would like to see how it will operate
> with 2 C6-0's and 1 C5-3.  EOM

If you don't plug the C6-0's with epoxy, you will have ejection at
burnout.  They will have plenty of pressure to eject the recovery
system.

Tim

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Scott McCrat » Sat, 13 Jun 1998 04:00:00



Quote:


>>However, if you want to put some spark, put a D engine mount (you can always go
>>back to B's and C's) and watch the action.  My next Prowler/Growler I plan to
>>build

>>will have a 3 18mm cluster engine mount.  I would like to see how it will
>>operate
>> with 2 C6-0's and 1 C5-3.  EOM

>If you don't plug the C6-0's with epoxy, you will have ejection at
>burnout.  They will have plenty of pressure to eject the recovery
>system.

>Tim

Right-O, except Tim didn't mention that modifying the motor by pouring epoxy
into is a violation of the safety code. Not that it wouldn't work and not that
it hasn't been done--just that you probably shouldn't do it. Another thing, with
three C motors that 3-second delay is likely to be way short. If you want to use
three 18mm motors, go ahead and use three C6-5s (C6-7s if altitude calculations
indicate a need for it). The extra ejection oomph caused by three ejecting
motors isn't normally going to cause any problems.

Scott McCrate
NAR 71680

------------------
Spam free Usenet news http://www.newsguy.com

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Buzz McDermot » Sat, 13 Jun 1998 04:00:00


Quote:

> I recently bought an Estes "Prowler" in a local hobby shop, after
> looking at it and deciding that it would be an excellent candidate for
> some modifications.  Here's a brief summary about how to turn your
> Prowler into a Growler.  (What *were* they thinking...B4-2, B6-2, C5-3,
> and C6-3?  Nahhh...this seems more like a D15 through F39 type of rocket
> to me!)

   < excellent kit bash review deleted >

Mike -

Great posting! This is an excellent example of what I consider to be the best form of kit
enhancement - you use as many as possible of the original parts, whether strengthening for more
powerful motors or bashing into a different design.

What I get a laugh out of are posts where someone buys a rocket kit, then proceeds to replace just
about everything but the nose cone before they are done!

Again, good post. And using the transition as a boattail was a cool idea.

Buzz McDermott
NAR 13559 TRA 1785  L2

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Buzz McDermot » Sat, 13 Jun 1998 04:00:00


Quote:


> > However, if you want to put some spark, put a D engine mount (you can always go
> > back to B's and C's) and watch the action.  My next Prowler/Growler I plan to build

> > will have a 3 18mm cluster engine mount.  I would like to see how it will operate
> > with 2 C6-0's and 1 C5-3.  EOM

> If you don't plug the C6-0's with epoxy, you will have ejection at
> burnout.  They will have plenty of pressure to eject the recovery
> system.

All of which is moot since the proper combination for this rocket would be 3xC6-5 or 3xD21-7. Don't
worry about booster motors!

Buzz McDermott
Dallas, Texas
NAR 13559  TRA 1785  L2

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by nojun » Sat, 13 Jun 1998 04:00:00


Quote:

> What did you do for the zipper-proof mod?

> Just wondering.

Robert:

        I have the rocket separate at the lower body tube joint rather
than ejecting the nosecone (which is tightly attached to the top tube).
The two upper tubes are glued together, then I sanded the couler that
sticks out of the bottom tube for a *slightly* looser fit.  I took a
piece of 1/4" basswood and cut a disc out of it just big enough to fit
into the top end of the coupler which is glued into the lower tube
section.  I drilled several holes into the disc, and attached a***
eye in the center.  This creates a vented bulkhead. that doesn't rely on
a shock cord being attached inside the lower body tube.  Even if it
ejects early or late the way the shock cord is attached helps to prevent
any major damage to the tubes.

Sport Rocketry magazine (the NAR magazine) had an article about the
zipperless design that I had just read before I saw the Prowler/Growler
kit in the store.

--
Mike
NAR #70953 - Sr/Insured/Level-1 ~ SeaNAR - The Seattle NAR Section #568
NO Junk Email, please! Real email to: amphoto [at] blarg [dot] net.
<NOTE: WA resident, could use the $500, has time for court!>

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by nojun » Sat, 13 Jun 1998 04:00:00


Quote:

> You know, If I were going to kitbash this one, I'd turn it scale, but if I
> *were* inclined to increast the impulse, It just cries out to be made into
> a 3 x 18mm engine cluster.  Line up the three BT-20's betwen the fin
> slots, and the fins can be reinforced between tubes.

hmmmmm....I was thinking about building another one later on, using 3
external "pods" to make it a 3x18 + 1x24.  A central D12 or D15 and 3
outboard "kickers"...that one would probably need a little bit of
noseweight, though <g>.  

Another mod that would be a little more work, but still fairly easy,
would be to either keep the 18mm or build up to a 24mm central mount,
then cut into the body tube and mount 3 18mm (or 13mm, or 24mm) tubes
"buried" 1/3 of the way into the body tube, with 2/3 of a nosecone on
each (make them like fairings), and vent the ejection to the outside.

Yeah, this kit leaves itself wide open to modifications; it's certainly
a good collection of parts to start out with.  

I think Estes has come up with a winner with this one.

--
Mike
NAR #70953 - Sr/Insured/Level-1 ~ SeaNAR - The Seattle NAR Section #568
NO Junk Email, please! Real email to: amphoto [at] blarg [dot] net.
<NOTE: WA resident, could use the $500, has time for court!>

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by nojun » Sat, 13 Jun 1998 04:00:00


Quote:

> What I get a laugh out of are posts where someone buys a rocket kit, then
> proceeds to replace just about everything but the nose cone before they
> are done!

> Again, good post. And using the transition as a boattail was a cool idea.

Thanks!  My original idea was to sort of try out the "zipperless" design
on a $12 rocket as a test before building something to fly on an H or I.
By Estes including the transition the way they did it was almost as if
they are saying "here it is...have a blast!".  By making it TTW and
using such hard balsa they opened up the kit to a lot of possibilities,
without having to replace everything ("jack up the paint job and slide a
new rocket under it").

--
Mike
NAR #70953 - Sr/Insured/Level-1 ~ SeaNAR - The Seattle NAR Section #568
NO Junk Email, please! Real email to: amphoto [at] blarg [dot] net.
<NOTE: WA resident, could use the $500, has time for court!>

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Bob Kapl » Sun, 14 Jun 1998 04:00:00


Quote:


>>If you don't plug the C6-0's with epoxy, you will have ejection at
>>burnout.  They will have plenty of pressure to eject the recovery
>>system.

> Right-O, except Tim didn't mention that modifying the motor by pouring epoxy
> into is a violation of the safety code. Not that it wouldn't work and not that
> it hasn't been done--just that you probably shouldn't do it. Another thing, with
> three C motors that 3-second delay is likely to be way short. If you want to use
> three 18mm motors, go ahead and use three C6-5s (C6-7s if altitude calculations
> indicate a need for it). The extra ejection oomph caused by three ejecting
> motors isn't normally going to cause any problems.

Thank you for filling in as RSO, and for pointing out that the 3 second
delay would probably be too short for this rocket.

BUT... anyone needing to "plug" questes booster motors for some sort of
application like this might try a technique I came up with several years
ago. I stuck a cork down the top of the motor casing. It's not permanent any
more than tape is, so it's perfectly legal. If you really want to get it out
after flight, drive a***eye into the cork and pull, or hack it out with
a knife if necessary. Pick a cork that's real tight. It will hold up to the
booster blow-thru OK. But put it in a conventional motor with an ejection
charge, and you've got the meanest pop-gun you've ever seen.

        Bob Kaplow      NAR # 18L       TRA # "Ctrl-Alt-Del"

Kaplow Klips:   http://www.FoundCollection.com/
NIRA:           http://www.FoundCollection.com/

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Armando Flore » Sun, 14 Jun 1998 04:00:00


I don't know if you have built any of the Custom or Quest kits, but they use
the Kevlar/elastic method on their kits.  My new Big Bertha has this
modification.  25 flights and no sign of wear with the original elastic on
the end of the Kevlar.  The original Big Bertha went over 45 flights, mostly
on C6's and the C5-3 (It is still around but retired).

I am going with your advice on starting out clustering with 3 A8-3s and work
it up.  My reason for wanting to use boosting was to show the effect to
young kids.  I have seen this before as a tyke and the effect gave an
everlasting and incredible impression.  Watching the 2 engines go out at the
same time while the 3rd continues on.  The rocket went up to about 300 feet,
I saw the apogee and the rest is history.

Thanks for the advice.

Armando Flores  Certifiable BAR

I have a big bertha/ranger model with 3 18mm engine mounts.  Even with more

Quote:
>noseweight that was necessary and some weathercocking, 3xC6-7s still eject
>before apogee, although it's pretty close.  I'd have to do it on C6-5s.
Also,
>the B4-6 was a great motor for this model.  Ejection was right at apogee.

>As far as ejection, you have to remember that the lower end of the shock
cord
>is going to get a lot of heat damage.  I have always heard each ejection
>charge separately, which means the first kicks the parachute, streamer, and
>the second two go right past the shock cord mount.  My original shock cord
>mount with epoxy was completely worn out and blackened after 7 or 8
flights.
>I wouldn't trust it to another flight.

>I really recommend this mod.  It's a great way to learn clustering and you
>can use A8-3 engines for the first flight unless you've really built a
heavy
>model.

>Ryan Coleman

 
 
 

Kitbashing a "Prowler" into a "Growler"...

Post by Jon38 » Sun, 14 Jun 1998 04:00:00


<snip excellent mod suggestions>

Quote:
><BR>
>I think Estes has come up with a winner with this one.<BR>
><BR>
><BR>
>-- <BR>
>Mike<BR>
>NAR #70953 - Sr/Insured/Level-1 ~ SeaNAR - The Seattle NAR Section #568<BR>
>NO Junk Email, please! Real email to: amphoto [at] blarg [dot] net.<BR>
><NOTE: WA resident, could use the $500, has time for court!><BR>
></HTML>

Uh-oh.  Now you've done it.  Estes will discontinue this kit for sure.

John O'Donnell  NAR 60742  Sr. L2                                              
                                                       CSAR Sec 113
Visit my web page at http://members.aol.com/Jon3854/index.html