User Profile: Chris


Member Since: November 29, 2010


  • February 22, 2015 at 12:03pm

    How is this a surprise? I learned about using a 9V battery and a piece of fine steel wool as a firestarter when I was in the Boy Scouts back in the early 60′s. I believe this is primarily an issue with 9V batteries (what they used to call “9V transistor radio batteries”) because of the proximity of the terminals and the higher voltage. It is harder to short across both terminals on a cylindrical cell like a AA or C cell. I haven’t tried it yet to see if it works with those batteries.

  • February 15, 2015 at 6:23pm

    There is a lot of effort going on right now to figure out how to safely integrate UASs into the National airspace. These efforts aren’t for little “hobbyist” type of vehicles but for much larger stuff to be able to fly in an environment that includes aircraft, including commercial aircraft.
    Eventually UASs will be able to electronically “see and avoid” other aircraft and will mix into the national airspace. None of these will be of a scale to be impacted by these rules – this looks like it focuses on the little stuff.

  • January 18, 2015 at 4:10pm

    To really be a drone it needs to be a lot more autonomous than an RC aircraft of whatever kind. If you can program it to take off, fly a flightpath and return without intervention from somebody on the ground then it is a “drone” although I like the not somewhat out of date term Unmanned Air Vehicle (UAV) better.
    Even if the big kids like the predators are monitored by a pilot while they are up, the vehicle does most of the flying on its own. Thankfully the armed ones still need somebody to decide what and whether to shoot.
    The military gets most of the press for UAVs but they are becoming a really good tool wherever the environment is dirty, dangerous, or dull. One of the coolest uses I’ve heard proposed would have a high altitude long duration UAV orbit over a developing hurricane so it could follow it from development to its eventual breakup and supply continuous real-time data the the ground throughout the storm.

  • January 18, 2015 at 3:55pm

    This isn’t a drone it is just an electric powered RC airplane. From the way he describes it, it may be an R/C sailplane with an electric motor.
    The sun didn’t bother the radio at all, it confused the pilot about the orientation of the aircraft.
    He is standing a the launch point with the transmitter in his hand watching the plane fly from a distance. Being able to control the plane requires that you be able to see it and know which direction it is pointing. Then it if flying away from you the controls work as you expect – right stick turns you right, left turns left. When it is flying toward you the controls reverse. If you want it to turn right you give it left stick and vice-versa since you are seeing it from the front.
    If you can’t see the plane because of the glare or you can’t figure out what direction it is pointing you can lose control fairly easily. One of my friends advised me to put a strip of aluminized Mylar tape on the wing leading edge so you had a chance to see the reflection as it turned toward you.

  • [1] January 11, 2015 at 1:14am

    One of the requirements for the NASA commercial launch project is that the companies involved meet both engineering AND business milestones. That means that they had to build a business model and attract outside funding to remain in the program. At least one company was dropped from the program because they couldn’t attract outside investment. A large part of the point here is that NASA did not want to foster a private space industry that was entirely dependent on NASA money to succeed. The ideal situation is that they build a viable business that stands on its own and NASA buys services from them when needed.

  • [2] January 11, 2015 at 1:05am

    The shuttle SRBs were parachuted into the ocean and recovered by two specialized ships that floated them and towed them back to shore. Since the SRBs were solid fuel most of their structure was empty tube once they were burned out. The nozzle, APU and actuator were pretty much in the bottom segment. Once they were returned they could be thoroughly cleaned and refilled. I suspect that the nozzles were one-time use, not so much because of the salt water but because of the erosion that occurred during the burn.
    The flyback capability of the SpaceX first stage is available, in part, because of the fact that it can perform its mission and still have enough propellant aboard to perform the landing. The Shuttle needed all of the impulse from the SRBs to get it into orbit, and was a much older design so the flyback capability wasn’t possible when it was designed.
    The SRBs ended up being solid fueled because, with the limited budgets available during development the engineering costs for the solid booster was lower than it would have been for a liquid booster even though the operational costs were higher.
    A major reason why the shuttle wasn’t as reusable as it was intended to be is because the design pushed the materials that were available to build it from far harder than expected. The shuttle main engines were the highest efficiency, highest chamber pressure engines ever put into an operational vehicle and they stressed the materials they were made from more than was expected.

  • January 7, 2015 at 11:49pm

    A light year is a measure of distance (not time!) and represents the distance that light travels in one year. The pillars are something like 7000 light years away from us, meaning that the light from them takes 7000 years to get here from there. In effect, the light that we see representing the pillars left there about 7000 years ago so we are seeing them as they looked 7000 years ago. If a supernova near them detonated 6000 years ago it would be another 1000 years before we see it happen. If a supernova near them detonated 6000 years or so ago they could have already been destroyed, we just haven’t seen it happen yet.
    Essentially, the farther away something is, the farther back in time you are seeing.

  • December 22, 2014 at 1:00pm

    Because Canada geese are bigger than most airplane engines can easily ingest and BOTH engines on his flight got hit and put out of commission.

  • December 22, 2014 at 12:57pm

    The difference is treating the way that Airbus makes their airplanes as something unique and revolutionary when US manufacturers have been doing the same kind of things for years.

  • [2] December 18, 2014 at 1:42pm

    Actually, it is the other way around. A satellite launch requires higher speed and more energy than an ICBM warhead, so satellites are are harder to launch than ICBMs. If you can launch a satellite you already have what you need for an ICBM.

  • [2] December 10, 2014 at 6:50pm

    Previous presidents have stretched the Christmas weekend by giving an extra day off when the actual holiday falls on a Tuesday on Thursday. the interesting thing here is that this action, which is clearly within his constitutional powers as head of the executive branch was done formally, over his signature and properly printed in the Federal Register while the other recent executive actions that do not appear to be within his constitutional powers get a more informal treatment, aren’t signed, and aren’t officially published.

    Responses (1) +
  • November 5, 2014 at 10:47pm

    We pay these guys to be up there but they make cool water blob videos in their spare time.

  • [1] November 5, 2014 at 10:44pm

    Same answer as Agent’s. just different words.. Surface tension means that the blob of water wants to pull itself into a sphere since that shape maximizes the volume and minimizes the surface area. Water is happier (which really means at an energy minimum) when it is completely surrounded by other water molecules. That lets it hydrogen-bond to the other nearby water molecules. The sphere is that shape that puts the fewest molecules on the surface. In this case the good of the many outweighs the good of the few.

    Turning gravity “off” – or really minimizing its influence – makes the other forces that are usually overwhelmed by gravity more prominent.

  • October 29, 2014 at 9:33pm

    I have yet to see **ANY** indication of an emphasis on “Muslim outreach” within the Agency, at least at the level of the average engineer or scientist. Every other major emphasis area ends up being reflected all the way down to individual performance plans.

  • [2] October 14, 2014 at 11:51pm

    My manager reviews my credit card purchases every month, or at least every month that I make a purchase. The people running the program review all of those approvals and they (and the whole program) get audited every year. Larger purchases get made by the procurement division with the people on my level developing the technical specs and reviewing the bids for compliance with the specifications but we don’t make the award, we make a recommendation.

  • October 14, 2014 at 11:45pm

    Actually, for purchase cards it is the bank that issues the card that doesn’t get paid until all of the month’s charges are reconciled. On the travel card the employee is on the hook to pay the bill when it comes due whether or not the government has paid them for it. If I have to travel the airline ticket (in the cheap seats, of course) gets paid for on my travel card and I pay the bill out of my own pocket when it comes. Normally the charges get through travel audit quickly enough that the government reimburses me before the bill comes but if they don’t I still have to front the government the money until they do.
    The purchase limit on the purchase card is $3000 per transaction. I have to reconcile my part of the bill every month – to the penny – then my supervisor reviews it and the people running the purchase card program review it after that.
    We aren’t allowed to mix government and personal purchases on either the purchase or the travel card. We also get training every year on what you can and can’t use the cards for.

    And, $3000 and below is considered a micro-purchase. Above that has to be done on a PR (which, it turns out, costs something like $140 to process) . The rules change at about $25,000 and again above $100,000. I think that in my 26+ years I’ve probably purchased two items above $100K and that was because I got handed the job of leading the process of buying a couple of major instruments for the rest of my group to use.

  • [1] September 29, 2014 at 9:03pm

    No, it just proves that most mutations aren’t improvements!

  • [1] September 17, 2014 at 11:28pm

    I was on a flight like that once. This was a 15-seat twin turboprop operated by the place I work. The cabin was pressurized, but it had been something like -20 the day before and the morning the flight left it was around 0. The trip to our destination was fine but on the way back we were fighting a strong headwind so they weren’t wasting any bypass air to warm up the cabin. I spent the whole two hours with my winter coat on and my feet tucked up under me to try to keep warm. Once we got home, my car, which had been cold-soaking in the parking lot all day actually felt warmer than the airplane had.
    That was a great plane, but as it got more and more expensive to operate we eventually discontinued its use and went all commercial.

  • September 14, 2014 at 11:11pm

    I saw that movie.

  • August 13, 2014 at 9:52pm

    This may be a choice, but it isn’t like choosing between McDonalds and Burger King for lunch. The problem is that when somebody is that deeply depressed they can’t see a lot of the other options. They can get to the point where they only see one option – they can’t believe/understand that there is any way that things can get better or that the pain will stop. It isn’t rational, but being rational is not one of the hallmarks of clinical depression.

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