Posts Tagged ‘air hose’

 

Launch Cage Test Day

We were fairly keen to try out the new launch cage so even though it was 33 degrees C (50 degrees C on the asphalt) last Sunday, we ventured out to our local launch  site to test the water rocket car with the new launch cage at launch pressures.

The water rocket car had the reinforced triple stack of bottles attached, which have been tested to 180psi. We also had the upgraded launcher using the high pressure hose, both of which hadn’t been run on the car before.

We were also trying out the new MD80 Camera which is a light camera mounted to the water rocket car.

The aim of the test day was to see how the car would launch out of the cage, if it was sticking in the guide rail or not launching straight. Here is the video of the launch day.

Results
Its not shown on the videos, but we did do a 60pis test and an 80 psi test before doing the 120 psi & 125psi tests. The 60psi and 80psi tests worked fine so we increased the pressure up to launch pressures. We didn’t include the video of these launches as they were not really all that  spectacular :)

We were pretty happy with the results of the cage test. The car on both high pressure launches is leaving the cage straight and there doesn’t appear to be any major loss of speed due to friction using the guide rail. There doesn’t appear to be any recoil of the cage and launcher and the cage held together well on launch. Getting the cage to the launch site also worked well, only issue was some strangle looks we got on the way there ;)

The MD80 camera worked ok, but we still have a few teething issues to work through as the first run didn’t record, or most likely, the second video recorded over the first one. We will work on that and possibly download videos from the camera between runs using a laptop, just to be sure.

The car once it left the cage was turning left, this was most likely just a slightly sticking front wheel, the wheel bearings were not greased before this test as we were not going for distance, which would account for the minimal rolling distance as well as the left turn. This should be easily fixed.

Here are a couple of video images showing the water rocket car launching. One of these is now posted on the dragstrer competition page on www.wra2.org , the page is here

Launch 2 - 125psi, very clean exit form the launch cage

Launch 1 - 120psi, nice exhaust plume when leaving the cage

Posted by on February 2nd, 2011 Comments Off

Barbed Gardena Style Fitting + Wire Cage Development

Barbed Gardena Style Fitting
The barbed Gardena style female quick connect  fitting we ordered arrived  today. This fitting has a  longer barbed connector that ensures the hose can be clamped tighter to the fitting so the hose doesnt  blow off under high pressure.  This one is made by Neta but is the same style as the Gardena ones and accepts a 9mm male nozzle. Thanks to the friendly staff at Dural Irrigation Supplies for going through the product brochures to find it and ordering it in specially :)

Barbed Tail Gardena style connector

You can see from this pic that the area available to clamp the hose to the fitting is much longer than a standard fitting.

Close up of barbed connector

We did a simple replacement of the existing fitting on the launcher and installed  this new female quick connect fitting  to the high pressure hose.

New connector attached to the launcher

Wire Cage Development
Members of the  Water Rocket Forum are currently in the process of writing a set of  rules for  speed and distance world records for water rocket cars. We are gladly taking part in this process to ensure people who participate do it in a safe and consistent manner. One of the items that will go into the rules is having a cage around the pressure bottles on the car to contain any fragments /  connectors in the case of a pressure vessel rupture and explosion.

The cage will need to ensure no piece bigger than 10mm x 10mm can get out of the cage. We have found a galvanised welded mesh product which is used for aviaries and chicken coops that has a mesh size of 6.5mm x 6.5mm. This will provide a sturdy cage which only requires 1 wrap of mesh. Typical chicken wire has a twisted hexagon  of 12.5mm mesh size which would require two wraps to meet the mesh size specifications in the rules.

Mouse and Snake Mesh - 6.5mm x 6.5mm

This closup pic shows the mesh size better – tape measure is in cm

Closeup of Mesh

We will make a couple of cages, one for the rocket car and one to do hydrostatic tests in. We will feel a bit safer doing burst tests now if the bottles are in the cage. We will just need to try to contain the noise of the explosion with a wrapping of carpet or something around the cage  :)

Once the rules are established and agreed we should be ready to  submit a record entry pretty soon there after with the current car :)

Posted by on November 5th, 2010 2 Comments

Updated Launcher – High Pressure Components

Next on the list was upgrading the launcher with metal connectors and high pressure hose.  We upgraded the following

– replaced the gardena quick release on the abort extension hose to a male Nitto connector
– replaced the  first gardena quick release on the launcher with a Nitto Female quick release
– replaced the poly hose on the launcher with high pressure hose (290 psi)
– replaced the poly  90 degree elbow with a metal 90 degree elbow with bards

The abort extension hose was the first to be updated and now all connections are Nitto air hose connectors, the male Nitto connector was added to the end. The barbed section goes into the hose.

Nitto Male Hi Cupla Std 30PH

Added Nitto male to end of abort hose (to connect to launcher)

The brass elbow was fitted into two sections of high pressure hose, one section has a Nitto female connector to connect to the abort extension hose, the other end has a gardena quick release to connect to the rocket nozzle.

90 Degree Brass Elbow with barbed connections

This section effectively converts from air hose connectors to gardena quick release.

High Pressure converter from Nitto Air hose to Gardena connector

We have managed to find a female gardena connector that has a barbed connection on the hose side. This barbed connection goes 30mm down into the hose and ensures there is  more space for the clamp to hold the hose to the  gardena connector.  At the moment there is only about 8mm-10mm of the gardena connector down inside the hose, so there is a chance it might  fly off under high pressure.  We  ordered the barbed one in from our local irrigation supply store, so we will probably replace the one we have on the launcher prior to the next launch with the new one once it comes in.

The high pressure hose and connectors were mounted back on the movable section of the launcher, strapped to the steel rod and screwed down.

High Pressure Hose mounted back on the launcher

All the sections  were connected up for a test and no leaks.  This configuration is upgraded to the high pressure hose and connectors from the pump to the launcher, here is a picture of all the sections connected

All sections of upgraded launch system

This current launch system lets us position the abort valve 5m from the launcher and the pump another 15m back from that if required for high pressure launches and tests. We will do a high pressure test of the hoses and connectors in this configuration without a bottle to ensure the system can hold without any leaks.

Posted by on October 28th, 2010 2 Comments

Updated Abort System – High Pressure Components

Abort System Upgrade
Our next launch day of the rocket car will be with the reinforced bottle stack and a launch pressure of approx 150-170 psi. With this in mind we have

– added 5m of high pressure hose to move the abort system back further  from the launcher
– replaced the lower pressure hose with the 290psi high pressure hose
– replaced the plastic T piece with a metal one and metal joiners
– mounted the hose and valve to a piece of wood for better stability when operating

Updated Abort System

The Abort extension hose has the Gardena quick release on the end of it currently as the launcher uses this for its quick release,  this will be replaced with a nitto quick release when the launcher is updated with the high pressure hose and connectors (this is the next planned  update).

Extended Hose and Gardena Quick Release

The T piece has  three 1/4″ BSP threaded male connectors. Each of the hose connections uses a barbed female 1/4″ BSP connector. The barbed section of the connector fits down into the hose and is clamped. The female threaded section screws on to the male connector of the T piece,  teflon tape was used to stop any leaks. The hoses are secured to the board with 15mm saddles .

Metal T Piece and connectors

Accurate Distance Measurement
We would like to get a accurate measurement of the next launch distance as (fingers crossed) it hopefully will be our longest yet. We have invested in a 50m tape measure to mark out the road with 10m increments as accurately as possible.

50m Tape Measure

50m tape measure

Posted by on October 27th, 2010 Comments Off