Modifying LOC Legacy Payload section for Altimiter

Modifying LOC Legacy Payload section for Altimiter

Post by Stephe » Sat, 28 Dec 2002 03:37:31



I want to modify the Payload section on my LOC Legacy so it can hold a
simple recording or peak altitude altimeter. What do I need to do?

--
Stephen Corban
NAR# 81338
When all fails, find someone
who knows what they are doing
Tripoli Quad Cities

 
 
 

Modifying LOC Legacy Payload section for Altimiter

Post by John Karpic » Sat, 28 Dec 2002 06:55:48


Nothing, except find something to fill up the space. The  Legacy has a long
payload section and the altimeter will slide around. Then you will need to
drill a hole so that the air can get the pressure sensor on the altimeter.


Quote:
> I want to modify the Payload section on my LOC Legacy so it can hold a
> simple recording or peak altitude altimeter. What do I need to do?

> --
> Stephen Corban
> NAR# 81338
> When all fails, find someone
> who knows what they are doing
> Tripoli Quad Cities


 
 
 

Modifying LOC Legacy Payload section for Altimiter

Post by Woody Mille » Sat, 28 Dec 2002 11:03:30


Drill a vent hole is good (if the altimeter needs it), but you may want
to actually mouth the altimeter to the AF, and not just "use something
to fill the space".

Without knowing which altimeter, my guess is your best option is to
mount the altimeter to something like a piece of G-10, longer than the
altimeter, with a T-nut on the bottom and top...

That way you can slide it into the payload section, line up the t-nuts
with a couple holes in the BT, and secure it with screws..

The other thing you probably will want is a "power switch", as some
altimeters don't like being powered up before they are in the launch
position.  This can be as simple as a hole to stick two wires thru, that
are twisted together on on pad and stuffed back in, to a real switch
(rotary, locking toggle, etc...).

Once this is done, a small hole in the bulkhead will allow using an
ematch/bp charge for ap deploy later..

Quote:

> Nothing, except find something to fill up the space. The  Legacy has a long
> payload section and the altimeter will slide around. Then you will need to
> drill a hole so that the air can get the pressure sensor on the altimeter.



>>I want to modify the Payload section on my LOC Legacy so it can hold a
>>simple recording or peak altitude altimeter. What do I need to do?

>>--
>>Stephen Corban
>>NAR# 81338
>>When all fails, find someone
>>who knows what they are doing
>>Tripoli Quad Cities

 
 
 

Modifying LOC Legacy Payload section for Altimiter

Post by Davi » Sat, 28 Dec 2002 13:18:46


You can mount it on a board or something, but I just stick mine loose in the
bay.  Put some padding in the bay (I use bubble plastic, or wadded
newspaper) above and below the altimeter.  Put the altimeter in something
soft - I slide mine into a sleeve made out of bike inner tube.  Make sure
you don't cover up the pressure sensor hole (if you're using a barometric
unit).  Drill a small (1/8") hole in the payload bay if you're using a
barometric unit.

And, the most important thing - put a***through the airframe into the
shoulder of the nosecone!  I lost a missileworks altimeter in a cow pasture
when the force of ejection charge caused the altimeter to slide forward
quickly and knock the nosecone off the payload bay.  It plummeted to its
death and was never seen again.

-- David

Quote:
> I want to modify the Payload section on my LOC Legacy so it can hold a
> simple recording or peak altitude altimeter. What do I need to do?

> --
> Stephen Corban
> NAR# 81338
> When all fails, find someone
> who knows what they are doing
> Tripoli Quad Cities

 
 
 

Modifying LOC Legacy Payload section for Altimiter

Post by Woody Mille » Sat, 28 Dec 2002 14:10:47


The "pack it with bubble wrap or whatever" scheme is very bad...  might
work with a low impulse motor, but anything more will cause the alt to
compress the packing, and maybe cover the vent or the sensor..
Something you won't know until it's got bad data, or the bird is DOA if
using electronic deploy.....

The size of the vent hole might be bigger than 1/8", based on the volume
of the bay - Missile works has some very good online doc, including the
needed calculations.......  For the Legacy, 1/8" would be fine...

Quote:

> You can mount it on a board or something, but I just stick mine loose in the
> bay.  Put some padding in the bay (I use bubble plastic, or wadded
> newspaper) above and below the altimeter.  Put the altimeter in something
> soft - I slide mine into a sleeve made out of bike inner tube.  Make sure
> you don't cover up the pressure sensor hole (if you're using a barometric
> unit).  Drill a small (1/8") hole in the payload bay if you're using a
> barometric unit.

> And, the most important thing - put a***through the airframe into the
> shoulder of the nosecone!  I lost a missileworks altimeter in a cow pasture
> when the force of ejection charge caused the altimeter to slide forward
> quickly and knock the nosecone off the payload bay.  It plummeted to its
> death and was never seen again.

> -- David


>>I want to modify the Payload section on my LOC Legacy so it can hold a
>>simple recording or peak altitude altimeter. What do I need to do?

>>--
>>Stephen Corban
>>NAR# 81338
>>When all fails, find someone
>>who knows what they are doing
>>Tripoli Quad Cities

 
 
 

Modifying LOC Legacy Payload section for Altimiter

Post by Davi » Sun, 29 Dec 2002 02:24:35


I've used this method up to an I284.  The padding material will compress
during motor burn, but will then un-deform as the acceleration decreases, so
by peak you are fine (for recording purposes).  You can't put anything
bigger than an I200 in a Legacy anyways (if that). If you wad the packing
loosely, the chance of the packing moving and creating an air-tight seal
over the vent hole is near zero (especially if you use newspaper).  It's a
lot harder to create an air-tight seal that it might seem.  The rocket is
going to have several seconds near apogee to equalize the pressure inside
the bay.

I certainly agree that for electronic deployment, you need the altimeter to
be carefully mounted so that it can't move.  But that wasn't the original
question.

-- David


Quote:
> The "pack it with bubble wrap or whatever" scheme is very bad...  might
> work with a low impulse motor, but anything more will cause the alt to
> compress the packing, and maybe cover the vent or the sensor..
> Something you won't know until it's got bad data, or the bird is DOA if
> using electronic deploy.....

> The size of the vent hole might be bigger than 1/8", based on the volume
> of the bay - Missile works has some very good online doc, including the
> needed calculations.......  For the Legacy, 1/8" would be fine...


> > You can mount it on a board or something, but I just stick mine loose in
the
> > bay.  Put some padding in the bay (I use bubble plastic, or wadded
> > newspaper) above and below the altimeter.  Put the altimeter in
something
> > soft - I slide mine into a sleeve made out of bike inner tube.  Make
sure
> > you don't cover up the pressure sensor hole (if you're using a
barometric
> > unit).  Drill a small (1/8") hole in the payload bay if you're using a
> > barometric unit.

> > And, the most important thing - put a***through the airframe into
the
> > shoulder of the nosecone!  I lost a missileworks altimeter in a cow
pasture
> > when the force of ejection charge caused the altimeter to slide forward
> > quickly and knock the nosecone off the payload bay.  It plummeted to its
> > death and was never seen again.

> > -- David


> >>I want to modify the Payload section on my LOC Legacy so it can hold a
> >>simple recording or peak altitude altimeter. What do I need to do?

> >>--
> >>Stephen Corban
> >>NAR# 81338
> >>When all fails, find someone
> >>who knows what they are doing
> >>Tripoli Quad Cities

 
 
 

Modifying LOC Legacy Payload section for Altimiter

Post by Kurt Kesle » Sun, 29 Dec 2002 02:36:19



Quote:
> I certainly agree that for electronic deployment, you need the altimeter to
> be carefully mounted so that it can't move.  But that wasn't the original
> question.

> -- David

I have seen Gwiz altimeters properly function after coming completely
off their mounting hardware and tumbling more than a foot into the
bottom of the rocket.  Not that I would recommend that situation ;-)
--
Kurt Kesler
 
 
 

Modifying LOC Legacy Payload section for Altimiter

Post by Mark Simpso » Sun, 29 Dec 2002 10:28:38


Quote:

> Drill a vent hole is good (if the altimeter needs it), but you may want
> to actually mouth the altimeter to the AF, and not just "use something
> to fill the space".

Caution: mouthing altimeters may be hazardous to your health. ;-)

Mark (couldn't resist) Simpson
NAR 71503 Level II