Reference / Paper · 2007
Peak of Flight #176: How To Set Up Multiple Flight Events In RockSim
Apogee Components' Peak of Flight newsletter, issue 176 (2007-01-30).
- peak-of-flight
- apogee-components
- model-rocketry
Reference / Paper · 2007
Apogee Components' Peak of Flight newsletter, issue 176 (2007-01-30).
Apogee Components' Peak of Flight newsletter, issue 176 (2007-01-30).
I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 How To Set Up Multiple Flight Events in RockSim INSIDE: • How To Set Up Multiple Flight Events in RockSim • Defining Moments: Foam Core • Web Sites Worth Visiting • Tip of the Fin: How To Fix Sticky Launch Lugs 1130 Elkton Drive, Suite A Colorado Springs, Colorado 80907 USA www.ApogeeRockets.com e-mail: [email protected] phone: 719-535-9335 fax: 719-534-9050 I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 How To Set Up Multiple Flight Events in RockSim by John Manfredo If you have a complicated rocketry project that has multiple electronic events included in it, there are ways to tell RockSim to do just what you want it to do. To start off, we will look at a large project and its events which will illustrate this situation perfectly in Picture 1. You will see a high power rocket design from RockSim. This particular design is a two-stage model with central motors in both stages and clusters in both stages. This means that the main motor for each stage is in the middle, and then there are multiple motors that surround them, which will ignite at a predetermined point in the flight. The Motors and Deployment The booster stage in this particular configuration has a central M1297 motor with six J570 motors that surround it. The upper stage has three I200 motors that surround a central K700 motor. Each stage has parachute recovery with the upper stage having a dual-deployment setup. The plan for the booster is to ignite the M1297, followed by the six J570's two seconds after the rocket goes into the air. A parachute will recover this stage safely after the two stages separate. About this Newsletter You can subscribe to receive this e-zine FREE at the Apogee Components web site (www.ApogeeRockets.com), or by sending an e-mail to: [email protected] with “SUBSCRIBE” as the subject line of the message. A P O G E E Page 2 Next, the upper stage K700 needs to ignite two seconds after stage separation. This will be followed by the cluster of three I200's firing to take it to about 18,500 feet above the ground. At that point, the smaller drogue parachute is deployed and finally, the main parachute pops-out at 1200 feet in altitude. All-in-all, there are eight different events that need to take place for this flight to work right: • Central sustainer motor ignites • Sustainer cluster ignites • Stage separation • Booster parachute deployment • Sustainer central motor ignites • Sustainer cluster ignites • Sustainer drogue parachute deploys • Sustainer main parachute deploys Beginning the Process The best place to begin is by loading the motors into the design, so I will go into the "Prepare for launch" screen by clicking on the button as seen in Picture 2. After loading the motors in each stage, I set the ejection delays and ignition delays as follows: The Booster The central motor in the booster has no ignition or ejection delay due to the fact that I need it to fire right away. Each of the motors in the booster cluster are set with a 2 second ignition delay so that they will start burning shortly after launch. The ejection delays for all of the cluster motors are set at 2 seconds as well. If the motor you are setting a delay on doesn't have the delay that you want, just highlight the delay space (see Picture 3), and type in the delay you want. Then, continued on page 3 Newsletter Staff Editor / Writer: John Manfredo Layout / Cover Artist: Dave Curtis Co-Editor and English Specialist: Michelle Mason R O C K E T S I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 continued from page 2 click on the "Return" key on the keyboard. This will save your setting. The 2 second ejection delay will give me 2 seconds from booster stage burn-out until the sustainer motor fires (it seperates the stages too). The Sustainer Now comes the time to set the events in the sustainer. The central motor in the sustainer gets no ignition delay, but the cluster of three receives a 2 second ignition delay so that they start after the main motor. As far as the ejection delays in the sustainer go, they are set at "none". Picture 4 shows the settings that I have done so far. Flight Events Now we need to set the flight events for each of the parachutes and their deployment. There are several options which can be used. For our purposes, the settings will be as follows. The booster will be set to deploy 2 continued on page 4 P/N 00508 A P O G E E R O C K E T S Page 3 I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 continued from page 3 Examining the Data seconds after stage separation, the sustainer drogue parachute is set to deploy at apogee, and the sustainer main parachute at 1200 feet before touchdown. Picture 5 illustrates these. I click on "plot graph", and RockSim will generate a graph based on the flight and data that I asked for. Picture 7 shows what the graph looks like (The blue numbers and associated legend were inserted by my- Now that all the events are set, it's time to get this project off the ground, so to speak. Select the launch button and let the simulation take its course. Once the simulation ends it is time to examine the data to see if all of the events went as planned. Setting Up the Graph Graphs are an incredible source of information. You just have to know how to set up a graph for the particular information you want to glean from it and also how to interpret the data once you have it displayed. For this situation, I want to see three things on the graph. The first is time, of course. I need to see the information over a given period of time to see how it changes. The second is thrust, so that I can recognize when each motor fires. The third and last label I need is velocity. This help identify the speed changes relating to parachute deployment. I will also need to set the graph data starting point to "0" and the graph data ending point to "40 seconds". These settings are seen in Picture 6. Once all the settings are in place, I am ready to generate the graph. self for your benefit so that you would be able to see the explanations better). As you can see, the red line indicates the thrust and the green line indicates the velocity. At point 1 on the red line, the central motor in the booster is indicated as having started by the increase in Newtons, which are listed on the left side of the graph. At point 2, the red line deviates from its path at 2 seconds which indicates that the cluster fired okay. At about the same point you can see how the green velocity line shifted a bit as well. This backs-up the evidence for the cluster firing, thus changing the velocity. The gap just before point 3 and the drop-off in the velocity at point 5 indicates the slowing of the rocket prior to stage separation and booster parachute deployment. Just after this gap at point 3, the sustainer central motor lights causing stage seperation; and there is another increase in velocity. At point 4 and the associated velocity line, there are more increases which show the sustainer cluster firing. Point 6 shows the drop-off in speed of the rocket indicating that the sustainer motors have burned out and the rocket is slowing down. The drogue parachute coming out is at a little over 30 seconds, which is shown as a change in the velocity continued on page 5 A P O G E E Page 4 R O C K E T S I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 continued from page 4 To Sum It All Up of the rocket again. This is shown in Picture 8. Looking a little further down the line there is indication of the main parachute deployment at about 290 seconds and can be seen in Picture 9. A P O G E E Now that all the data has been examined, I can see that all of the flight events have worked flawlessly. As I said before, the graph in RockSim can be a powerful tool when used in the right way. This is the reason for doing an article like this; so that your RockSim skills can "take off"! If you haven't tried this powerful software yet, please go to http://www.apogeerockets.com/rocksim.asp, take a look, and download the demo! You will quickly find out that this design and simulation software is something you can't be without. R O C K E T S Page 5 I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 TIP OF THE FIN When you put your rocket on the launch pad, make sure it slides easily both up and down the rod. If it gets stuck going down the rod, this usually means that it will get stuck on the way up as well. This has the potential to become dangerous if the rocket becomes stuck at liftoff and it tips the pad over. A little sanding on the rod or the inside of the launch lug(s) will help prevent this and insure a flawless liftoff. Always perform this check prior to launch. Call us at: (719) 535-9335 or e-mail John at: [email protected] for details! "Apogee Books" is not affiliated with Apogee Components. But they do sell some nifty space books, and we do recommend them. A P O G E E Page 6 R O C K E T S I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 DEFINING MOMENTS A Foam Core Fin increases the strength of a fin etal framework. Bond the skin directly to the foam and without significantly increasing its mass. You can insert any structural members. Epoxy is usually a safe adheexpanded polystyrene into the hollow areas.This will sive to use on foam, while polyester resins and instant add strength and stiffen the skins. glues may melt it. Again, the type Skin from balsa or cardstock The added strength is usually so of skin should be appropriate for remarkable that many structural the expected loads and the shape Hardwood caps members inside the skin can be of the fin. Flat and stiff skins such eliminated and this decreases the as light cardboard, thin balsa, thin mass of the wing. plastic, or thin plywood are suitConstructing a foam core strucable only to fins with flat surfaces. ture is similar to building a built-up For curved surfaces, fiberglass structure. Start by creating a skelcloth soaked in epoxy is genereton framework around the fin and ally better. Several layers of fiberPlastic foam core cut a piece of foam to fit any holglass can be added to give extra low area. Shape the foam using a Foam core fins are good candidates strength to the fin. This technique for high power rockets sanding block so it exactly matches is especially applicable to larger the perimeter defined by the skeland higher-powered rockets. Foam Core Graphic from Model Rocket Design and Construction www.apogeerockets.com A P O G E E R O C K E T S Page 7 I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 Web Sites Worth Visiting There are many of you who I'm sure know about our website worth visiting. I found this site a long time ago when I was first getting back into the hobby. I was searching for some information on my first model rocket from when I was in junior high school, which was an Estes Patriot rocket, as seen in Picture 1. I really thought it was huge way back when! Follow the link http://www.ninfinger.org/ ~sven/rockets/rockets.html to Sven Knudson's website and you will be transported back in time to see a lot of your favorite rockets too. Sven has just about every catalog page posted from companies such as Centuri, Estes, Vashon, Enerjet, FSI, LOC, North Coast Rocketry, and many more! As you can see in Picture 2, the cover of the 1960 Estes 3-page catalog was pretty plain! There are links to clubs and personal rocketeer webpages as well as some interesting links to White Sands and Robert Goddard Museums. I thoroughly enjoyed taking a trip down memory lane to see a lot of my favorite models over the past 30 years or so. I'm sure that you will, too. By the way, thanks for the link to our website Sven! ������������� ������ � ���������������� ����������������������������������������� ������������������������������������� �������������������������� ������������������������������������� ����������������������������� ������������������������������������������ ������������������ �������������������������������������������� �������������������������������������� ����� ������ �������� ������������������ ������������������������ ������������������������������ www.ApogeeRockets.com/go-box_controller.asp A P O G E E Page 8 R O C K E T S I S S U E 1 7 6 - J A N U A R Y 3 0 , 2 0 0 7 Question & Answer Ryan writes to us in regards to the Perfectflite Altimeter (http://www.apogeerockets.com/Altimeter.asp) and asks, "With the USB data transfer kit, how many flights can be recorded? The website reads one at a time, so is it possible to save the recorded data to a memory stick or does it need a computer? More specifically, I have a little USB transfer device which allows me to copy data from one USB device to another without the computer as long as the USB devices have a FAT12, FAT16 or FAT32 file system. With this device I can copy stuff from my camera to a memory stick. Would the altimeter be able to be used with a device like this?" A P O G E E The answer comes to us via the people at Perfectflite themselves. They say, "You do need a computer. Unlike a camera, memory card, etc. the altimeter does not function as a simple data storage device. It contains its own protocol for transferring flight data (among other functions) so it will only communicate with our software running on a host computer. It will not interface with a device that copies the contents of one USB storage device to another." R O C K E T S Page 9