Comments by "SeanBZA" (@SeanBZA) on "Scott Manley"
channel.
-
2
-
1
-
1
-
1
-
1
-
Helicopters tend to avoid negative G for noise abatement purposes. Heck of a noise as the rotors hit the tail if you pull negative G past a point. Some helicopter designs include in the tail a heavy steel cutter bar, designed so that you get a very audible warning, as it chews the tips off the main rotor blades, that what you are doing is not a good idea. Yes you will need all new rotor blades, very expensive, and a good pit of panel work to fix the hole cut in the tail rotor, but still cheaper than losing the airframe.
Do remember having a flight with some really stressed out pilots, who had spent 3 hours turning in circles to calibrate the magnetic compasses after a replacement, and I took the flight back instead of driving on the tractor. Sitting in the cabin, door open, legs out and holding to the strap, with the sky below my feet, and the ocean visible through the rotor blades, as they were doing barrel rolls in this 16 ton helicopter. Yes it could lift cargo, 16 tons max at sea level, and if you could fit it inside, it would carry it.
1
-
1
-
1
-
Probably supplied by the same company, just had a little more care taken in processing to keep thickness variation, always there with thin foils, to a minimum, and to have a single pass pressing, so both sides are shiny, unlike the regular foil in which 2 foils are done at a time, with a thin oil coat between to prevent sticking, so as to cut time and cost. the foil from the roller is rolled onto a wide long roll, then goes to a slitter, where it gets cut to a width, then the length of foil required per pack is rolled onto the disposable mandrel in the box.
1
-
1
-
1
-
Outer layer would be destroyed by the sun, but the aluminium under will be mostly fine, except where the plastic of the threads has been destroyed, so the blankets will have sagged and deformed, with likely some of the structure visible now. Paint exposed will be basically only the oxide pigments, and the mineral powders and fillers, nothing organic left, except where sheltered. Glass exposed could likely be a lovely blue from photon and electron bombardment, though most of it would be brown for the same reason. Thin film of dust on everything, as it rains down from the sky, as a result of micrometeorite bombardment nearby causing dust to fly up, and also from static charge causing particles to levitate in the vacuum from charge generation due to impact from solar wind protons and electrons.
1
-
1
-
1
-
1
-
1
-
1
-
1
-
1
-
1
-
@-danR High pressure gas comes into the check valve, then there is a orifice plate to provide some flow restraint, and then the burst disk. In the space between the 2 units you can add a simple leak detector. For the oxidiser just use a high pressure electric feed through and a plain low carbon steel thin wire that will be corroded open if there is any leakage, and similar for the fuel, as it is also corrosive. Cheap, and can be integrated into the flange and orifice plate as well with ease, along with a pressure test port. You could also add in pressure transducers and a low pressure fill with gas, but pressure sensors that will survive that fuel and oxidiser are not cheap, nor are they low mass, as you need a diaphragm and transfer fluid to keep from melting the silicon strain gauges, which are ironically the cheapest part of the sensor.
1
-
1
-
1
-
1
-
@paulhaynes8045 The phone has GPS yes, but also the towers, because they have a fixed nearby location, also will send the ephemeris data for all the locally visible satellites to the phone on request, so the phone GPS can lock really fast, and it also uses the time difference between local towers to gat a very fast and somewhat accurate location if indoors, so that it can at least give a position to within 30m almost immediately, even if there is no sight of the sky for GPS signals. The GPS signal is used outside in your car, to track better, but rough location is done using the signal strength and timing of local towers.
Did once turn on a phone GPS with no coverage from the network, and it took around 20 minutes to finally position me, within a 100m sphere, while another phone, with service and data, took under a minute to position, using data and the 2 visible towers to get a rough area to gain coarse position fast. GPS in your phone needs data, stand alone GPS can do without it, though your accuracy improves with time on, as it refines errors out long term, though you also get the map used providing some sort of sanity check, as there is an assumption if you are moving you are on a road, allowing it to remove parallel paths easily.
1
-
1
-
1
-
1
-
Not necessarily that the parachute will fail to operate, it could, because of the Russian space program wanting simplicity and robustness, have a very simple pressure capsule that was only armed by a pin being pulled during separation, that now is waiting for the pressure to approach a part atmosphere, which would be the opening pressure in the upper Venusian atmosphere, and thus acting as a backup for the electronic trigger, or it also acts to power up the lander, as it would assume it was doing reentry, and thus connect the internal batteries to the electronics. 50 years and the batteries might have still some residual charge, enough to have it give a final few seconds of swansong, as the radio transmitter operates for a few moments before they deplete completely.
1
-
1
-
1
-
1
-
1
-
Remember every survivor of an ejection does get a tie pin from Martin Baker, as testament to surviving the event. Fun thing is the speed at which it does eject you does compress your spine, so you will only ever eject once, as the second time might kill you. Your legs get pulled in with straps, but your hands are not pulled in, instead you have both hands on either the top ejection pull ring, or the one between your legs. You do though want to pull your legs in before, as there is a rather good chance if you do forget that those straps that pull your legs in to the seat are there, and that they pull your feet in by being attached to the airframe, and pull in while the seat is busy making you 10cm shorter. You have a greater than 50% chance that unprepared your ankles and shins will be broken.
Yes have chatted to pilots that survived landing separate to the plane, and met the one who landed missing large parts of the airframe behind his seat, but still had a working engine (sans afterburner, seeing as the missile hit that), and no parachute or brakes. Him ejecting would have been fatal, he is a little past the design envelope for that particular seat design, and ejecting would mean his head was the canopy breaker. Fighter pilots are in general short and stocky, because the cockpits are designed for short and stocky people. Very uncomfortable for bigger or taller people like me to fit in there.
1
-
1
-
1
-
As more satellites were added in different orbits, accuracy improved. With low numbers of satellites, and also with long paths through the air to provide diffraction of the signal, you got poor accuracy. More orbits meant more visible at any time, and thus a more precise position. You need, IIRC, at least 4 to get a coarse position in 3 axes, and with every added satellite visible at the same time your error reduces. At 6 you get 100m, and with more the error reduces further, with most receivers able to handle up to 12 simultaneous decodes at a time, and with more sophisticated receivers using ADC units that can sample at the actual chirp bit rate, timing each individual bit as it comes in, and thus being able to correct for smaller drift with each cycle.
Some of the software defined units have no real limit on the number of satellites they can view simultaneously, just depends on the amount of memory and processor speed, as you can always add more of both, and make the rake receiver scale with visible satellite numbers. Some of those have impressive cold start capability, being able to start from cold within a few minutes, and with warm start capability of seconds, provided the data they have is not too stale.
Big issue is with noise, you find that often GPS signals in urban areas are poor, lots of RF noise desensitising the receiver, and also urban canyons making for lots of multipath distortion, and limiting visible sky to use. Sometimes I need to restart the old Garmin I have a few times, as it is unable to start, but often during RF quiet times it will be up and running in 2 minutes, from a warm start.
1
-
1
-
1
-
@ericlotze7724 Not much about VFD's other than they all die eventually. The SOS construction because you have to grow a film on an insulator for electrodes, and sapphire in pure form is transparent, and making the whole clock in the display area is possible, as the electronics can all be coated with silicon nitride to provide isolation afterwards, except for some bumps at the edge of the device that are built up with aluminium to make the top layer connections. You probably will want to use an electrochromic display instead of LCD though, as that saves a lot of power, though you will still need to have a capacitor to store the energy needed to refresh the display, which likely will only update once a minute. But same construction physically as LCD, just needs a very low current high voltage (around12V) power source to do the update.
Going to be fun to do the crystal drive though, with nanowatts of power available, and typical watch crystals being in the microwatt range for drive. Battery array likely to be a lot bigger and thicker than the display. your wristwatch is going to be Rolex Oyster size, and only rated to 10m depth.
1
-
1
-
1
-
1
-
1
-
1
-
1
-
1
-
1
-
1
-
1