LOC Magnum with 2 h180s ????

LOC Magnum with 2 h180s ????

Post by Christiaan Jacobs N9V » Thu, 21 Nov 1996 04:00:00



The LOC Magnum comes with one 54mm mount and 2 29mm outboards.
I have a friend who certified with this rocket at Danville and we were
thinking of trying to fly it on just 2 H180 RMS 29mm motors. Has anyone tried
this motor configuration before? Is it enough? What kind of flight to you get?

Tnx in advance.

Chris TRA#4948
and level one certified now.  Great time at Danville a bit cold and rainy but
hey I got my nose cone back!!!!!!

 
 
 

LOC Magnum with 2 h180s ????

Post by DG » Thu, 21 Nov 1996 04:00:00


Quote:

> The LOC Magnum comes with one 54mm mount and 2 29mm outboards.
> I have a friend who certified with this rocket at Danville and we were
> thinking of trying to fly it on just 2 H180 RMS 29mm motors. Has anyone tried
> this motor configuration before? Is it enough? What kind of flight to you get?

> Tnx in advance.

> Chris TRA#4948

Chris:
I don't want to discourage anyone from doing clusters, because I enjoy
doing them very much myself, but I don't recommend flying the Magnum
this way.

Two H180's have a total impulse of one I211, which is a low & slow
flight (1000' +/- depending on how heavy you built it, short delay or
altimeter needed).

Rule #1: Never use Copperheads for clusters

I recommend that you always fly it with a motor in the center hole. With
no center motor, if one of the outboards lights before the other, you
will have a very unbalanced, low speed takeoff that will likely hit the
ground shortly after leaving the launch rod.  Then the other one lights,
and you have a "land shark"

Another reason to not do it this way is cost and complexity: The retail
for two H180's is about $30.  Plus, you'd need at least two ignitors
instead of one.  Therefore, you could buy an I211 instead and save about
$5, or take the $30 plus the money you saved on the extra ignitor, and
get an I284. Then you won't have to load (and then clean) two motors,
etc. etc.  The I284 will fly about 30% to 40% higher and with fewer
potential problems than the two H180's. YMMV

I can tell you that an I284, J350 or I435 (or a Kosdon I400 for your new
520 ns casing) center motor with two H180's in the outboards is an
awesome flight with a big roar and lots of flame.  For a lower-altitude
flight, you could try it with an H242, or I357 in the center and two
H128's or two G80FWL's in the outboards.  When clustering, try to have a
center motor that has average thrust at least 1.5x or preferably double
of what each outboard has.  Typically this means either a much larger
center motor, or a Blue Thunder (or Kosdon FAST) motor in the middle
with White Lightning (or SLOW) in the outboards. I recommend that you
put two small to medium-sized ignitors such as two Firestar FS-18's
(rather than one medium to large one such as a single FS-24) in the
center motor as a failsafe to make sure that it lights.

Always make sure that the launch control system can handle the extra
current requirements.  Check for beefy output wire, and check the
breaker(s) for rating - should be at least 10A for each Firestar ignitor
you're using (considerably less needed for HiRMI or Daveyfire), and that
the battery is well charged.  Checking the voltage with a meter is a
good idea.

If you're still determined to fly it on two H180's, I recommend that you
use the two ignitors per motor trick for both of them.

One last word:  When clustering, always do a continuity test on each
individual ignitor before you twist them all together.

Happy Flying!

--
DG
TRA #4666

 
 
 

LOC Magnum with 2 h180s ????

Post by Frank J. Bur » Thu, 21 Nov 1996 04:00:00


Winroc shows 1300 feet and a short delay, given a cd of .7 and a weight of 6#.
I'd want to be pretty sure I lit both those motors though, or at least have
an altimiter backup in case one didn't light and it only went 400 feet or so.

Frank



Quote:
>The LOC Magnum comes with one 54mm mount and 2 29mm outboards.
>I have a friend who certified with this rocket at Danville and we were
>thinking of trying to fly it on just 2 H180 RMS 29mm motors. Has anyone tried
>this motor configuration before? Is it enough? What kind of flight to you get?

>Tnx in advance.

>Chris TRA#4948
>and level one certified now.  Great time at Danville a bit cold and rainy but
>hey I got my nose cone back!!!!!!

 
 
 

LOC Magnum with 2 h180s ????

Post by DG » Fri, 22 Nov 1996 04:00:00


Quote:

> Winroc shows 1300 feet and a short delay, given a cd of .7 and a weight of 6#.
> I'd want to be pretty sure I lit both those motors though, or at least have
> an altimiter backup in case one didn't light and it only went 400 feet or so.

> Frank

The lightest Magnum I've ever seen (one that was actually glued
together and painted, and has all its hardware and chute mounted) weighed
7.5 lbs "dry", measured on a digital scale.  Fantasy weight may vary.  
The good news is that the CD is from 0.5 to 0.6 depending on how well
it's finished.  Mine weighs 11.5 lb (it's got a longer payload section,
is Kevlar/carbon/glass reinforced, and has 4 fins) and a CD of 0.6.

If it's stock and you want to use outboards only, you'd better have an
altimeter because the outboard tubes are not full length so you get NO
ejection from them.

If you launch it on 2 H180's and one doesn't light, don't worry about an
altimeter.  A shovel might be more useful.

--
DG
TRA #4666

"Not everything that can be counted counts,
and not everything that counts can be counted" -
Albert Einstein