Maniac Motor Mount Too Far Back

Maniac Motor Mount Too Far Back

Post by Kempist » Sun, 19 Jul 1998 04:00:00



As I was putting the motor mount into a Estes Maniac the glue seized too soon.
As a result, the motor is now going to be 5/8 inch further back (aft) than it
should be.  Will this affect stability?  If I have to add some weight to the
nose, how much should I add?  I'm guessing that this will not make any
difference but this is my first D powered rocket pre or post BAR and I don't
want to lawn dart it in front of 20 other people at the club launch next month.

BTW, Estes calls this thing level three.  What a joke.  The only reason they
call this thing level three is the sparsity of the instructions and the
attention to a couple of details to make sure it survives D & E thrust levels.
Big Bertha (Level I) was harder to put together becasue of the fin gluing but
it had very detailed instructions.  On the plus side I had 75% of the Maniac
done in 30 minutes or less (didn't time myself).  With my schedule that's about
all I can spare in an evening to build.

Thanks in advance for any help!
-- Mark

 
 
 

Maniac Motor Mount Too Far Back

Post by Bob Fortun » Sun, 19 Jul 1998 04:00:00


Quote:

> As I was putting the motor mount into a Estes Maniac the glue seized too soon.
> As a result, the motor is now going to be 5/8 inch further back (aft) than it
> should be.

   sounds salvagable if you keep the cg where it was originally, that
is, at the forward launch lug.  add some clay "snakes" through the hole
in the nose cone to change the distribution squishing them into the nc
with a dowel. then call this motor mount feature a "boat tail" and
everyone will be impressed by your engineering prowess.

   a more fun way to fix it would be to remove the misplaced mmt and its
couplers and insert a 29mm motor mount tube using multiple winds of 1/4
or 1/2 inch tape as centering rings and epoxy into place.
this way you can fly it on an F or G and never worry about your previous
glue challengement. :-)  see the maniac thread earlier on this newsgroup
about glassing for strength and speed.  they really scoot on these
motors!

bob fortune

 
 
 

Maniac Motor Mount Too Far Back

Post by The Silent Observe » Sun, 19 Jul 1998 04:00:00


Quote:

> As I was putting the motor mount into a Estes Maniac the glue seized too soon.
> As a result, the motor is now going to be 5/8 inch further back (aft) than it
> should be.  Will this affect stability?  If I have to add some weight to the
> nose, how much should I add?  I'm guessing that this will not make any
> difference but this is my first D powered rocket pre or post BAR and I don't
> want to lawn dart it in front of 20 other people at the club launch next month.

You shouldn't find any problem with that amount of difference in the
motor mount location.  The Maniac, like many other Estes kits, has a
good bit of excess stability.

It might be advisable to run a VCP or other CP calculation and balance
the rocket in launch configuration before attempting to fly it on an RMS
24/40, though; that motor (especially with E and F loads) is a little
heavier than an Estes D12.  Even that, though, is probably okay.

Quote:
> BTW, Estes calls this thing level three.  What a joke.  The only reason they
> call this thing level three is the sparsity of the instructions and the
> attention to a couple of details to make sure it survives D & E thrust levels.
> Big Bertha (Level I) was harder to put together becasue of the fin gluing but
> it had very detailed instructions.  On the plus side I had 75% of the Maniac
> done in 30 minutes or less (didn't time myself).  With my schedule that's about
> all I can spare in an evening to build.

If you look over the Estes catalog with an eye toward skill levels,
you'll note that any model that uses D motors, no matter how trivial to
build (like the Maniac, as the extreme case) is Skill Level 3 or
higher.  They've done that just to put off complete novices who don't
know how to get a motor mount glued in place so it stays, I think;
there's certainly (as you point out) less work in building a Maniac well
than there is in building either a Big Bertha (skill 2) or an Alpha
(also skill 2).

Of course, what they don't tell you is that any competent *** (the
sort who don't cut themselves trying to pick up a single-edge razor
blade) ought to be able to start with Skill 2 and make any skill 3 or
skill 4 kit in the catalog as a second rocket -- assuming they're paying
attention and don't get in a rush.

--
 WARNING!!  This area has been designated an official DOPE FREE ZONE!!

      If you're going to be a dope, please do it somewhere else!

Donald Qualls, aka The Silent Observer           NAR # 70141-SR Insured
Rocket Pages             http://www.FoundCollection.com/

Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.

 
 
 

Maniac Motor Mount Too Far Back

Post by Greg Holdr » Sun, 19 Jul 1998 04:00:00


: As I was putting the motor mount into a Estes Maniac the glue seized too soon.
: As a result, the motor is now going to be 5/8 inch further back (aft) than it
: should be.  Will this affect stability?  If I have to add some weight to the
: nose, how much should I add?  I'm guessing that this will not make any
: difference but this is my first D powered rocket pre or post BAR and I don't
: want to lawn dart it in front of 20 other people at the club launch next month.
:

Same here but with 3/8"*** out. What glue did you use? I used
5min epoxy. I figured I didnt use enough so that when thei
motor mount was almost there the glue was so sparse which
prevented lubrication. I think the next one will be with more
glue and I will go faster to get it in.

--
Greg Holdren

 
 
 

Maniac Motor Mount Too Far Back

Post by Kempist » Mon, 20 Jul 1998 04:00:00


Quote:
>Same here but with 3/8"*** out. What glue did you use?

I used Elmers yellow wood glue.  Usually I put quite a bit in but this time I
tried being a little less wasteful.  

If I build one again, I'm going to put a used D engine in the MM so I have
something to push against.  Also it looks like my thumb fits nicely into the
bottom of the motor mount so I could push evenly with it.

I should have realized that this was going to happen, I had the same problem
with the green motor maount band but enough pushing moved it to the center of
the MMT.

-- Mark

 
 
 

Maniac Motor Mount Too Far Back

Post by Kempist » Mon, 20 Jul 1998 04:00:00


Quote:
>Same here but with 3/8"*** out.

BTW,  How does it fly?

-- Mark

 
 
 

Maniac Motor Mount Too Far Back

Post by Greg Holdr » Tue, 21 Jul 1998 04:00:00


: >Same here but with 3/8"*** out.
:
: BTW,  How does it fly?
:

Flew great! D12s, D15, E11 so far, well until last launch.
It it suffered to many free falls from the heavens and as we all
know the BT above the fin unit likes to crimp up on the Maniacs.
After 3 falls it was to much to use CA to re-enforce it anymore.
I choped it up and used the BT for making a Rastrocam,
(Rear facing Astrocam). The last mod on the rocket was with Kevlar
line doubled up and epoxied on the "E" to "D" convertor ring.
Guess where it broke? Yep, at the epoxy joint. Like others have said
,"Kevlar does not like tight bends with glue". Next time
I will wrap around the MM tube while building. Extra coupler
for the area above the fin unit.    

--
Greg Holdren