Welcome to the Water Rocket Computer Model HTML Help Pages. These form a companion to the context sensitive help that is associated with each control on the computer model itself.

These pages are organised so that using the computer model can be quick and easy for the novice, yet sufficiently complex to satisfy the curiosity of the experienced.

Basics

	Getting Started
	When you first load the simulator, you are presented with a screen that tells you a few basic things about the running of the program and how to navigate around using the key. At the bottom of this page there is a check box that allows you to elect not to see this screen again (don't worry, you can get it back if you make a mistake). Following this, you are presented with the start-up screen that always appears at the beginning and presents you with some options. You can go onto the program without altering anything just by pressing or letting it count down. The options you are given regard: the `level' of the user (Novice or Expert); the units you want pressure in (Bar or psi); and, the height measured in metres or feet. Your selection is stored in a zero length configuration file so that they will appear as the default the next time you run the program. Pressing takes you onto the main screen.
	First Calculations
		Just Press
		To do your first calculation, you can use the default values set in the model - there is no need to change anything. All you need to do is to click on the Calculate button or press . Once you have done this, a basic set of results will be displayed in the window in the top right - these are results that people are most interested in when doing calculations (There is a more complete set of results on the quick graphs page - see Results and Quick Graphs). If you have a real rocket and want to find out how it will perform, just enter the values that you can measure on the Input Parameters sheet and press Calculate.
		Changing Values
			Novice Level
			You can just enter the values but if you prefer and you have started on the Novice level, you can use the Wizard (right) to help you enter the values. You can get the Wizard while the variables frame is visible just by pressing or by double-clicking the mouse on the help box in the top-right of the screen. The meaning of each step is explained and once you have finished, you will be ready to launch the rocket.
			Expert Level
			At Expert level, just enter the values directly into the fields on the Input Parameters sheet and press Calculate. Common values of all but one of the Environmental Variables may be entered quickly by pressing the appropriate letter. With the Gamma and Density of the gas in the rocket, both variables may be altered at the same time by entering the uppercase character - the Gamma and Density of CO2 may be entered just by pressing E.
	Files
	If you want to save your rocket for future reference or modification, you can press save and a form will pop up allowing you to choose a file name and save your work. Note that the units you use for pressure or height do not alter the data stored in the file and therefore this information may be sent to different people who use different unit sets and they will get the same results as you. To load a file that has already been saved, press the load button and a form will pop up with a file list window. Highlighting any file will display the description of that file as long as the Automatically view description box is checked. If it is not, a Description button appears allowing you to see the description of the highlighted file. You may choose to do this if your file system is slow (if you are working from a floppy disc) or one of the files is known to be corrupted for some reason (my advice is to delete the file).
	Print
	You can print out a hard copy of the model - the input parameters, the model parameters (time slice and so on) and the results - by pressing the Print button. This allows you to print to a selected output device (on LPT1:, LPT2:, LPT3:, COM1:, COM2: or to a file), including a form feed if required. The output device is remembered by the program as is the decision regarding the inclusion of a formfeed at the end of the print (the form feed just makes the printer push out the rest of the piece of paper after it has finished printing - the amount of paper on continuous paper stock depends upon the setting on the printer for paper length). The file name suggested is in the form WRCM????.TXT where ???? is a number from 0001 to 9999 and the suggested number is automatically incremented from the highest file number in existence. So, if the highest file is WRCM2135.TXT, the suggested file name is WRCM2136.TXT. If you have got to 9999, it will always suggest WRCM0000.TXT - 10000 without the leading 1. Introducing a file called WRCM9999.TXT will force the suggested file name to be WRCM0000.TXT and by default, it will be appended so a single file with all of the results in may be created - especially useful in a class with many users if you want a single file as output. You can select any 8 character filename as the output file although README.TXT and READ1ST.TXT are reserved and the program will not allow you to print over these. By default, a file will be appended but you do have the option to overwrite a file with the same name. If you what to quit the print form without printing then just select Done.
	About
	The about button simply displays the current version information . . . Water Rocket Computer Model Release V 4.30 Copyright (c)1994 - 2000 P. A. Grosse. All Rights Reserved. e-mail pagrosse@compuserve.com http://ourworld.compuserve.com/homepages/pagrosse/h2oRocketIndex.htm A specially adapted version of Version 1.0 of this model was distributed on the cover disc of PC Plus Magazine in issue 131, September 1997 in Wilf's Programmer's Workshop. This Version gives a new, easier to use interface, parachute, launch tube and T-nozzle options, launch angle, quick graphs including 3D graphs and takes into account research done by AWARS members into the real effects of fluid flow into nozzles. The 3D optimisation now includes the ability to adopt a set of parameters directly from the graph thus speeding up optimisation by an order of magnitude. This program is distributed only as a zip file as an e-mail attachment or direct download from the above site (with MD5 hash for security). If you obtained it via any other route, you need to e-mail the copyright owner at the above address. You will also receive details of any further updates via e-mail. See the readme.txt file for further details regarding updates and registration (this program is postcardware). Postcardware is like shareware but a while ago, I decided that because paying was such a pain - getting money in a foreign currency and then sending it off in the post with all of the worries associated with it getting there safely - I would give up on the idea of ever making any money out of 26 years of programming experience and ask simply for a postcard from the person who uses the software, of a place near to where they live. This is a great deal simpler, easier to do and costs a lot less.
	Exit
	In the unlikely event that you should ever need to get out of the water rocket computer model program, I have thoughtfully provided you with an Exit button and, just to make sure that you have not made a horrible and regrettable mistake by selecting it, you are asked to confirm your intentions.
	Keyboard
	It is possible to get around the program using just the keyboard although you will hit something of a functionality brick wall when you get to the 3 Dimensional Optimisation where you will need a mouse to do some of the things there (but not all). Generally speaking, you can jump around the input fields by pressing so that you can modify any of the input parameters. You can alter any of the fields by typing in the numbers although it is worth pointing out that when a field first gets the focus, it will highlight the whole number so if you press any valid input key other than an arrow key, it will overwrite the existing value. This is a useful function but if you are not aware of this, it can seem like a hindrance. In addition, you can press from any field on the Input Parameters and the model will calculate.
	Caveat (or Finally)
	One thing to remember is that this is a computer model and not a real water rocket and the results will only be meaningful if they reflect your real rocket therefore you should take care to make reasonably accurate measurements. The model will give you results to one decimal place or even two under certain circumstances. However, in real life, you may find it difficult to measure the diameter of a nozzle or weigh a lightweight rocket. Some things you will not be able to measure unless you have a wind tunnel or a sophisticated fluid flow test-bed. In these circumstances, example values are given by the model and you can use your own judgement as to the value you enter. In addition to this, there are a number of things that can make the real flight differ from the predictions such as the nozzle being non-axial, the parachute deployment being earlier than expected (or not at all or the parachute getting tangled), wind speed, launching downwind of a small hill and so on. At best, any computer model can only provide a starting point. Used at its best, modifying the variables according to real flights that you do, you can make the results more meaningful. The real trick is to use the model to find out what will fly, how much you can vary things without affecting performance or endangering people and go out and have a lot of fun. Play around with the model and find out what happens when you change various values - you may find that you can vary the amount of water by 100mls either way and only affect the height by 0.5 metres. If you want to build water rockets and wonder how you can do so, you can have a look at my water rocket web pages on http://ourworld.compuserve.com/homepages/pagrosse/h2oRocketIndex.htm which show you how I tackled the problems and found solutions. This is only one way of doing it and I recommend that in addition, you look at a number of other people's web sites to form your own opinions on water rockets - links are at the bottom of the index page. On these help pages, there are a number of links. The links to these help pages are in bold text and the external web links are not. You can visit any of these help pages without a connection to the Internet as you have downloaded the whole `site' in the zip file. Have fun. P a u l G r o s s e Author of the Water Rocket Computer Model. Copyright ©2000 Paul Grosse. All Rights Reserved.