Monday, October 01, 2012

Launch Report 2012-15

Location: The 'hood
Weather: mid-60's, wind 0 mph, clear
Total flights: Today - (7) -; YTD - 80
Total motors: Today - -; YTD - 95
Motors by class YTD: 
(Air-25); (H2O-4); MicroHybrid-1; MMX-6; A-6; B-5; C-32; D-7; E-23; F-6; G-9


Since the there wasn't a hint of any wind, I stayed in the neighborhood for a few test flights. The rockets I flew (pictured) included: A 2-L water rocket based on Quest components, my old Hydro-1L, the Guillows Shuttle and a modified Mike Bauer stomp rocket. On the latter, I trimmed down the upper fins to increase its stability. As a note for future reference, the double sided tape assembly method appears to work great on fins but the tape tends to come loose on the nosecone section. 

Here is a run-down on the operation of the Quest water rocket launcher:

  1. The assembly is easy, the stake down is secure and the release mechanism works easily.
  2. Unfortunately, with the direction of the pull string and with the launcher tilted (a feature on the stake), the rockets will naturally angle over your head. They'd be easier to watch and there would be less chance of you getting wet if the release was actuated from the other side. This could be accomplished with stakes on 2 legs.
  3. You either have to unhook the launcher from the stake or plan to spill a little water. No biggie.
  4. The kit includes a second washer, which was required for my 2-L bottle.
  5. The kit is only intended for up to 80 psi  and is intended to leak above that.
  6. The recommended water volumes are 100mL for 1-L and 200mL for 2-L. These sound low for optimal altitude, but I forgot what I read so long ago. This will be easy to research on-line.
  7. At 60psi and with 200 and 400mL, the 2-L rocket is unstable. I'll have to look for a longer, skinnier one and try again.
The results follow:
  1. Quest water - I only had one washer in the screw-on nozzle and it leaked like a sieve. I pulled the release at an unknown pressure with an unknown amount of water and it anemically lobbed off the pad.
  2. Quest water - The 2nd washer was installed. I used 200 mL and launched at 40 psi. Unstable.
  3. Quest water - 400 mL and 60 psi. Unstable. At least the water rockets pressurize quickly.
  4. Hydro-1L - 400 mL and 60 psi. Stable but not that impressive. I need to see if I can find some notes on the previous flights.
  5. Guillows Shuttle - I flew it at 30 psi and pointed it at a low angle. It looped over and landed nearby. I don't know how to add more nose weight without killing its glide unless I modify the wings. This was pretty much expected but I had hoped the laws of physics would have been on a lunch break.
  6. Guillows Shuttle - 40 psi and a steep angle. Same results.
  7. Paper stomp - 40 psi. With the trimmed fins, it had just a hint of a barrel roll. High flight with a nice lawn dart in the rain-soaked ground. No nose cone damage but the 2-sided tape on the nose cone's shoulder released. It stuck back but undoubtedly is getting less secure with each flight. 
Update for future reference: I found some information about the Hydro-1L thanks to the Wayback Machine.  I used a simple, low-tech, automatic mechanism to release the water rocket (via James Yawn). Here, a tire valve was inserted through a hole in the bottle cap. When the pressure builds sufficiently, it is pressed through and the rocket launches.  Because I had to set the electric pump going and back off, I never saw the launch pressure. I should have set the pump at an angle and used a set of binoculars...but I didn't. Here are two examples.

Nozzle opening/water volume/results (alt. is a WAG)
13/32" / 500ml / ~45' alt., launch at ~45 sec
13/32" / 300ml / ~85' alt., launch at ~45 sec

2 comments:

  1. Looking good Dick :)
    "The recommended water volumes are 100mL for 1-L and 200mL for 2-L. These sound low for optimal altitude, but I forgot what I read so long ago."
    These do seem low for max altitude, but should still give you fairly good results. The one thing the lower water amounts will give you is higher acceleration off the pad. Here is a whole article on the optimal amount of water to use: http://www.aircommandrockets.com/water.htm

    - George
    PS. Welcome back to the light side. :)

    ReplyDelete
    Replies
    1. Thanks George. I looked at some of the info on your site but not that page. I also played with the simulator you pointed to but only ran a few examples. The page you just provided should fill in the blanks. It could very well be that the smaller amount of water at a slightly higher pressure than I first tried would make for a stable flight (lees weight and faster launch speed). I will try that before I recycle the Quest parts (including prying the foam bumper off the nose cone). I was a bit surprised that my earlier flights were better than the ones off the Quest set up.

      PS - I know the quest launcher is suboptimal, but I hope to get reliable flights before introducing it to my grandson :)

      Delete