Posts Tagged ‘modules’

 

Slow Progress

Progress has been slow this last 2 weeks, or maybe the weeks just went past a lot quicker than usual :)

We have been working on building 3 wrockets to take to our next launch day. A one bottle wrocket a 2 bottle wrocket and a 3 bottle wrocket. I want all the wrocket to have at least 1 parachute. The single bottle will have a main chute module, the 2 bottle will have a main chute module as well as a drogue chute module and the three bottle will have a main chute module as well as a drogue chute module. Hopefully this way we can get some more testing done on the dual chute setup.

PL Glued Chute Structures
The additional wrockets have meant building additional modules which is in progress. These new corrugated cardboard structures have all been glued with PL Premium instead of my usual metal pins method.

I haven’t put the elastic bands on them yet for the pressure plate, but the sides seem fairly strong. Here are some pics

Main Chute Module - PL Premium

Main Chute Module - PL Premium


Main Chute Module (side)  - PL Premium

Main Chute Module (side) - PL Premium


Main Chute Module (inside)  - PL Premium

Main Chute Module (inside) - PL Premium


My PL gluing skills need a bit of work but the second one was better than the first one.
Here is a drogue chute module structure
Drogue Chute Module - PL Premium

Drogue Chute Module - PL Premium


Drogue Chute Module (side) - PL Premium

Drogue Chute Module (side) - PL Premium

Fin Fix
After the last launch day we had a fin come loose. I decided to remove the metal pins and glue the fins to the RFA. These seem very solid now. Ready to fly again.

Small RFA - PL Premium

Small RFA - PL Premium


Small RFA (Close Up of Fin) - PL Premium

Small RFA (Close Up of Fin) - PL Premium


The side attachments as well as the spine of the fin itself is glued to the bottle.

New Timer Mounting
As we have a new method of mounting the Tomy timers, we had to order some more, 5 arrived today .. so these will be put to good use in the chute modules with both the timer and the mount itself being used. The rest unfortunately, goes in the bin :(

5 New wind up Tomy Toys

5 New wind up Tomy Toys

Posted by on December 1st, 2008 1 Comment

Main Parachute Module + Large PPNC Dummy Module

Main Parachute Module
After the last crash, we decided to split the main parachute module and the PPNC Nosecone.

We used the same design as the drogue parachute module for the main module by shrinking the bottom section of a 1.25L bottle and cutting the top off. The existing nosecone structure and door panel were used. The tomy timer was stuck on top of 3 layers of corrugated plastic to enable the handle section to protrude past the wall of the rocket.

Main Parachute Module

Main Parachute Module

This module weighed in at 54 grams minus the parachute. Click here for other module weights.

Full Size Dummy Nosecone
The dummy nose cone was built from a new bottle. This one is a full height dummy nosecone. A small section was cu tout of the bottom so as not to interfere with the door of the main parachute module. We also decided to fly it without the bubblewrap to see how it would fair in a crash.

Full Size Dummy Nosecone

Full Size Dummy Nosecone

This module weighed in at 23 grams . Click here for other module weights.

Posted by on October 19th, 2008 2 Comments

PPNC Dummy Nosecone Module

One of the downsides to crashing a wrocket with the PPNC Main Parachute module is that the nosecone itself in almost all cases needs to be replaced. This usually means redoing the door and holes for the tomy timer. Whilst this is not overly difficult, on a flight day if we have a crash like this it usually means the end of testing the parachute mechanism as its usually damaged enough not to work.

With this in mind we have come up with the dummy PPNC nosecone module. If on flight day we have a crash most of the damage will be to the dummy nosecone and the thinking is we can just put another dummy PPNC nosecone on and fly with the parachute again. These PPNC Dummy nosecones take literally 5 minutes to make, so we can have a few of them at the ready.

Here is the dummy PPNC nosecone with its bubblewrap padding.

PPNC Dummy Nosecone

PPNC Dummy Nosecone

Its a bit smaller than the normal size PPNC simply because this is what we had left after making the door for the Drogue Chute Module.  We may decide to make it full size in future. Here is a pic next to the PPNC Nosecone module and main chute.

PPNC Dummy Nosecone v's PPNC Nosecone with main chute

As with the other modules it fits snuggly onto the shrunken bottle bottom undernearth, wether this is another module or a pressure bottle. Here is the PPNC Dummy module with the Drogue Chute Module and a shrunken pressure bottle

PPNC Dummy Module + Drogue Chute Module + Shrunken Pressure Bottle

PPNC Dummy Module + Drogue Chute Module + Shrunken Pressure Bottle

We have added this to the module weights page, the PPNC Dummy Module weighs in at 22 grams (0.776 oz)

Posted by on October 10th, 2008 Comments Off

Dual Deploy Nose Cone – Part 2

Rethink
After building the SSPPNC and thinking about the servicing problems I was facing, I came to the realization that this SSPPNC didnt really fit with our philosophy of a modular approach to water rocket construction. Rather than building a SSPPNC that could deploy both chutes we decided to leave the PPNC as it was and build a drogue chute module. The idea being that this module could be added or removed from the rocket based on the requirement of the launch.

Bottle Shrinking
One problem we have found when fitting and aligning the parts of the rocket was the fact that the diameter of the PPNC is smaller than the bottom section of the PET bottle, not by much but enough to have it not fit on straight and sometimes having to be realigned after taping.

We decided to use George’s method (http://www.aircommand.com) of shrinking the bottom of the bottle. This ensured the PPNC slides over the bottom of the bottle underneath it in the rocket. See Georges video about the 4:00 minute mark for how to shrink a bottle. We didnt quite have the water boiling but Im guessing around 80 degrees C. We immersed the bottom of the bottle a few times until we had it the size we wanted.

Here is a pic of 2 x 1.25L bottles. The bottle on the left is a standard bottle, the bottle on the right has had the bottom shrunk slightly.

Shrunken bottom of 1.25L bottle (right)

Shrunken bottom of 1.25L bottle (right)

Although they look very similar there is a big difference when connecting the modules together. This is best shown with a video. So here one is. In this video I am connecting the new drogue parachute module to one of the rockets pressure bottles. First connecting to one I have shrunk, then to an untouched bottle. You can see the difference.

Drogue Parachute Module
In part one of this article we showed the nosecone structure for the drogue deployment module. As we have now decided to make a drogue module that can be added or removed from a rocket, we needed an enclosure that would allow this. The obvious choice was to use the bottom section of a shrunken bottle.  This will allow the PPNC module to fit over the top of it, it also allows this module to fit over another module (a future payload module) or the bottom of the pressure bottles.

Drogue Chute Module

Drogue Chute Module

We have used bubble wrap as fill in the top section (its lighter than sponge), the size of the structure and door opening is smaller, to take smaller chutes, but the tomy timer configuration and air flap is the same as the PPNC module

Putting The Modules Together

The modular method we have used to shrink the bottom section of the bottles allows the modules to be easily put together to form the rocket combination we desire. Here is a video of the PPNC module, drogue module and out pressure bottle being assembled. For liftoff they are taped together. This method makes module alignment much easier.

I have weighed the modules and shown it here for those interested. You can always get to this from the Menu section of the site then under categories then weights.

Dual Deployment
Here is a test run of both chutes deploying, the modules are connected to H2. We will do a bit more testing prior to launching this configuration, however so far so good. The air flaps detect launch and will sit closer to the rocket body during acceleration

Posted by on October 7th, 2008 Comments Off