I had a very productive meeting with about a dozen students interesting in becoming engineers. Once I clarify a few details in the PowerPoint file I used as an information resource during the meeting, I plan to make a pdf copy of it available on the web and announce it here in this blog.
I'd be happy to answer any questions this summer, and I expect to repeat this session as a program at the TCC "STEM Center" this fall. Watch for announcements on campus.
Please stop by my office (SM 290) or e-mail me (carrj -at- tcc.fl.edu) if you are interested in pre-engineering advising or joining the Engineering Club.
Wednesday, June 3, 2009
Saturday, May 2, 2009
Historic Amateur Rocket Launch
Although our team did a nice job, this launch of a 1/10 scale Saturn V really takes the cake. At 1648 pounds and 36 feet tall, it is one serious rocket. I've seen a K motor launch a 7+ foot hybrid rocket to about 3500 feet. That went up with an impressive roar. This one must have been something to see in person.
See also this guy's photographs, such as this one (notice the person in the foreground for scale!), and some of the "related" videos. For example, this video follows the flight from launch to deployment.
By the way, notice the scaling laws at work here. It is 1/10 as tall as a 363 foot tall Saturn V, but a tiny fraction of the 6,699,000 pound original. This is not just due to the difference between length and volume scaling. Scaling up the mass by a factor of 103, which keeps the density constant, only gives 1,648,000 pounds. The missing factor of four or so is due to the fuel (and extra thrust) needed to put a 260,000 pound payload (a lot even if scaled down to 260 pounds) into low earth orbit rather than "just" send the rocket up to 4440 feet.
The thrust of the model rocket was 7700 pounds force, almost exactly 1/1000 of the 7,648,000 lb-force thrust of the Saturn V's first stage. The much greater thrust-to-mass ratio of the model makes it take off "like a rocket" rather than lumber off of the pad as the real one did, but the latter could burn for 150 seconds. If you never saw the Apollo rocket go up, here is one video of the usual TV launch view we saw (where you get a sense of the fact it took more than 10 seconds to clear the tower), and another (higher resolution) view looking down at the first stage engine section from the point where the final fueling connection is broken, about a dozen seconds before ignition. (A similar sequence is used on the Shuttle, which also has a connection to the main fuel tank that remains until it is time to pressurize the tank.)
See also this guy's photographs, such as this one (notice the person in the foreground for scale!), and some of the "related" videos. For example, this video follows the flight from launch to deployment.
By the way, notice the scaling laws at work here. It is 1/10 as tall as a 363 foot tall Saturn V, but a tiny fraction of the 6,699,000 pound original. This is not just due to the difference between length and volume scaling. Scaling up the mass by a factor of 103, which keeps the density constant, only gives 1,648,000 pounds. The missing factor of four or so is due to the fuel (and extra thrust) needed to put a 260,000 pound payload (a lot even if scaled down to 260 pounds) into low earth orbit rather than "just" send the rocket up to 4440 feet.
The thrust of the model rocket was 7700 pounds force, almost exactly 1/1000 of the 7,648,000 lb-force thrust of the Saturn V's first stage. The much greater thrust-to-mass ratio of the model makes it take off "like a rocket" rather than lumber off of the pad as the real one did, but the latter could burn for 150 seconds. If you never saw the Apollo rocket go up, here is one video of the usual TV launch view we saw (where you get a sense of the fact it took more than 10 seconds to clear the tower), and another (higher resolution) view looking down at the first stage engine section from the point where the final fueling connection is broken, about a dozen seconds before ignition. (A similar sequence is used on the Shuttle, which also has a connection to the main fuel tank that remains until it is time to pressurize the tank.)
Thursday, April 16, 2009
Rocket Project Success
Many of you know this already, but the rocket project has been carried out EXTREMELY WELL by our team. Their official competition launch was successful and came within 86 feet of the target altitude of 2000 feet. One test launch (over at the launch site in Madison County run by the NFCC Sentinel Rocket Club) had reached 2900 feet, so the rocket was capable of much more than the competition demanded.
This was the only non-hybrid rocket, so it was guaranteed to win its class. However, I was particularly pleased to read the following in the e-mail from the director of the competition:
I believe that means our team would have won an "open" competition against the teams launching hybrid rockets! As I said above: you did an EXTREMELY IMPRESSIVE job.
By the way, team members, don't think that detail about "most consistent with your reports" is a minor compliment. Teams have won major national competitions (like the concrete canoe race in civil engineering or some of the robot competitions in mechanical or electrical engineering) because their documentation and project presentation took top marks over a team that was slightly better in what they thought was the main competition. Being tops in both metrics (consistent reporting and hitting the target altitude) is a real triumph.
This was the only non-hybrid rocket, so it was guaranteed to win its class. However, I was particularly pleased to read the following in the e-mail from the director of the competition:
... we had 6 teams competing in the hybrid competition and your team was the most consistent with your reports and you were closer to 2000 ft.
I believe that means our team would have won an "open" competition against the teams launching hybrid rockets! As I said above: you did an EXTREMELY IMPRESSIVE job.
By the way, team members, don't think that detail about "most consistent with your reports" is a minor compliment. Teams have won major national competitions (like the concrete canoe race in civil engineering or some of the robot competitions in mechanical or electrical engineering) because their documentation and project presentation took top marks over a team that was slightly better in what they thought was the main competition. Being tops in both metrics (consistent reporting and hitting the target altitude) is a real triumph.
Wednesday, April 8, 2009
Laser pointer danger
I told one of my classes this semester about the availability of Class IIIb laser pointers (at a non-trivial cost) and their legal use for pointing out stars - and the serious risk of a felony conviction if they are misused.
Today I saw an article from the BBC about a police helicopter equipped specifically to detect, locate, and arrest persons who point such devices at aircraft that includes video of a demonstration. You can see the dangerous effect of the laser in an aircraft cockpit as well as the use of FLIR (infrared vision) to track the perpetrator. Side links to earlier articles indicate that misuse of these lasers has been a growing problem in the UK over the past year or so.
Today I saw an article from the BBC about a police helicopter equipped specifically to detect, locate, and arrest persons who point such devices at aircraft that includes video of a demonstration. You can see the dangerous effect of the laser in an aircraft cockpit as well as the use of FLIR (infrared vision) to track the perpetrator. Side links to earlier articles indicate that misuse of these lasers has been a growing problem in the UK over the past year or so.
Update: Electric Cars
One of my students told me the electric car show yesterday was excellent. Among other things, he got to see a Tesla Roadster!
The Tallahassee Democrat has a photo gallery from the event. (Yep, there he is in two of the photos.) I've seen the plug-in converted Prius (pictures 5 and 6) around town, but only heard about the Dodge Caravan last Friday. Now that is a serious bit of home-brew car conversion!
The Tallahassee Democrat has a photo gallery from the event. (Yep, there he is in two of the photos.) I've seen the plug-in converted Prius (pictures 5 and 6) around town, but only heard about the Dodge Caravan last Friday. Now that is a serious bit of home-brew car conversion!
Tuesday, April 7, 2009
Friday, April 3, 2009
Electric Vehicle Event (April 7)
Attention Solar Cart workers!
The Tallahassee Area Electric Vehicle Association (taeva.org) and Electric Auto Association (EAA) are having a special event in conjunction with a TAEVA chapter meeting on Tuesday, April 7, at 3 PM.
There will be hybrids, plug-in hybrids, and all-electric vehicles (including locally built conversions) on display, but the real attraction is the Spirit of FC plug-in hybrid that is on a tour of all US state capitals. That link takes you to the blog describing the tour. Today (April 3) they are on their way to Birmingham, Alabama, then on to the capital in Montgomery before heading to Tallahassee.
The meeting location, at the Tallahassee city "Fleet Management" center (400 Dupree St), is convenient to TCC so it would be easy to go over there after class on Tuesday afternoon. TAEVA has a map showing the meeting location on its website. Dupree is halfway between Appleyard and Mabry, south of Pensacola.
The Tallahassee Area Electric Vehicle Association (taeva.org) and Electric Auto Association (EAA) are having a special event in conjunction with a TAEVA chapter meeting on Tuesday, April 7, at 3 PM.
There will be hybrids, plug-in hybrids, and all-electric vehicles (including locally built conversions) on display, but the real attraction is the Spirit of FC plug-in hybrid that is on a tour of all US state capitals. That link takes you to the blog describing the tour. Today (April 3) they are on their way to Birmingham, Alabama, then on to the capital in Montgomery before heading to Tallahassee.
The meeting location, at the Tallahassee city "Fleet Management" center (400 Dupree St), is convenient to TCC so it would be easy to go over there after class on Tuesday afternoon. TAEVA has a map showing the meeting location on its website. Dupree is halfway between Appleyard and Mabry, south of Pensacola.
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