Jack Crossfire's blog View Details
Archive for June, 2017
Posted by Jack Crossfire | Jun 28, 2017 @ 10:48 PM | 4,221 Views
It's quite clear that the lunchbox steering has been hunting, ever since the encounter with Asian capitalism. A rear wheel was damaged, so it bounces up & down. This makes the gyro oscillate, which makes the steering erratic. Its damaged state is a good time to try more aggressive techniques of locking the tires to the wheels.

The lion kingdom started seriously considering installing a camera & sound system for making eye level vlogs from the vehicle. 10 mile runs can get extremely boring & a lot of thoughts come through a lion's mind. It would be a much smaller camera than a gopro, suspended by a guywired carbon fiber rod. There are now lots of keychain cameras advertising "1080p" for under $40. Wireless headset microphones are now under $50.

Then of course, there's the DJI Mavic. There is a way to make a 1 handed remote control for it & fix the altitude so it follows an athlete semi autonomously. It would be 20 minutes at a time, but enough to capture a speed mile. There wouldn't be a way to drive a ground vehicle simultaneously. The Mavic would need to accurately track a speed. For $1000, the video would be watched by 20 people.
Posted by Jack Crossfire | Jun 25, 2017 @ 01:55 AM | 5,211 Views
The day had finally come to install short circuiting switches on the Mastech. Many circuits were fried because its current limiting was set too high. It was too much trouble to unplug the circuit & plug in a short circuiting wire to set it.

Despite looking simple from outside, the front panel is packed on the inside. There was only 1 place to squeeze the switches in. The LEDs had to be sandwiched between the switches & the plastic. At this time, another desire emerged to have switches for turning off the individual outputs without turning off the manes, but this would have been a much more incremental benefit than the short circuit switches.

With it all installed twice, the switches pointed at the current dial when they were shorting & pointed at the voltage dial when they were open. This was the most intuitive orientation. They worked very briefly, at low voltages & all current up to 5A. When the voltage was set to 30V, the switches quickly failed closed.

The switches open by a spring force which the human has no control over. The human can merely press the spring to make contact, but the spring must break contact by its own force. The spring had arc welded to the contact. It could be broken apart & reassembled, for the most part. Despite being rated for 6A 120V, the switches still failed at 30V 5A.

The best the internet can come up with is 120V AC ratings being equivalent to 14V DC, because in AC there is a zero crossing after 8ms to break the arc while in DC, the arc can continue. While the power supply limits current when quiescent, there is a very high inrush current when short circuiting it. The Chinese must have encountered the same problem, said "f*ck it" in Chinese & left out the short circuit switches.
Posted by Jack Crossfire | Jun 25, 2017 @ 01:09 AM | 5,033 Views
The lion kingdom long dreamed of a switch allowing a heat gun to blow cold air. It would cool hot glue. The deed was finally done. The wires were not intuitive. The big red & black pair didn't power the heating element, but probably powered the thermocouple. It was the tiny black pair connected to CON1.

Unfortunately, it takes a very long time for the heating element to cool off. The switch has to be off when it 1st comes on or it'll take 30 minutes to blow cold air. It does indeed cool hot glue.
Posted by Jack Crossfire | Jun 24, 2017 @ 02:48 AM | 4,530 Views
The story sounds great until you realize in order to reuse the 1st stage, they have to throw away 34% of the payload, according to Kiwipedia. There are no dual geostationary satellites at a time or payloads of opportunity like the Arianne 5.

Given this fact, let's calculate the cost of launching the same mass with reused 1st stages & expendable 1st stages. The shotwell said it costs "less than half" to reuse the 1st stage, which we'll assume means half. The 1st stage is 2/3 of the total cost, so that gives a total cost of 2/3 / 2 + 1/3 as the cost of a flight proven booster.

So the 1st launch of 1 payload costs 1 for each system. The later launches cost .667 for flight proven & 1 again for expendable. With these parameters, the cost/lb for flight proven approaches but never goes below the expendable system. The problem is the discount for a flight proven rocket exactly matches the reduction in payload.

As soon as the flight proven booster gets anywhere below 1/2 the cost of a new booster, it saves more than the reduction in payload & it becomes favorable. Just reducing the refurbished cost to 40% of a new 1st stage would barely start breaking even after 7 launches. If they miraculously got it to 10% of a new 1st stage, they would start saving huge amounts of money after 3 launches.

Even in the miraculous case, they wouldn't start saving money until 3 launches. So far, they've only gotten 2 launches from the reused 1st stages, so they're losing a huge amount of money. The future is still heavily dependent on new Falcon 9's being much cheaper than other rockets, with the hope that someday they can reuse just 1 booster for a whole year with much lower refurbishment costs.
Posted by Jack Crossfire | Jun 24, 2017 @ 01:19 AM | 4,621 Views
So Heroineclock II's mane problems were it had an offset crystal & it was calibrated from a computer RTC which itself was offset. It gained 5 minutes over 77 days. Its internal clock increments 250 times per second. Thus, it needed to subtract 5 * 60 * 250 ticks every 77 * 24 * 60 * 60 * 250 ticks or 1 tick every 22176 ticks.

Unfortunately, it had an existing trim factor of adding 1 tick every 10300 ticks, so the 2 trim factors need to be combined. The trick was to multiply 22176 * 10300. This predicts the existing trim factor adds 22176 ticks for every 22176 * 10300 ticks & the new trim factor subtracts 10300 ticks for every 22176 * 10300 ticks. Thus, the total change in ticks every 22176 * 10300 ticks would have to be 11876 or the addition of 1 tick every 19233 ticks. The new addition is less frequent than the old addition, so it satisfies the need to slow the clock down.

We still need to reduce the 19233 to 19230 make sure the clock doesn't run slow.
Posted by Jack Crossfire | Jun 22, 2017 @ 10:05 PM | 3,996 Views
After a few more days, a few hundred electrical & mechanical connections, the container was fastened. It's not as trivial as it looks. It hauled 3.6 lbs without flipping over. The wheels spun quite a bit on any uphill & it high centered. Because all the wheels are now fixed, it can now be supported by 2 front wheels & 1 rear wheel, leaving 1 rear wheel to spin.

The next step was installing a carbon fiber handle. After much debate, the decision was made to not make the handle removable. This limited objects to much smaller dimensions than the maximum, but clearly just as big as the previous container. The holes were cut just big enough to press fit the handle in. If they were expanded & cotter pins installed, the handle could be removable.

With the amount of material now removed from the original lunchbox, it was hardly worth its full price. The 1st drive was 6.8 miles. 3 miles had headlights & payload. 1 mile was at 10mph. It used 2777mAh.
Posted by Jack Crossfire | Jun 18, 2017 @ 07:17 PM | 4,708 Views
After 3 years, the lunchbox finally got run over by an H1B, as expected. It confirmed H1B's are indeed the lousiest drivers. It is a great irony how the most advanced software & the most money in the world is made by people who grew up with no modern appliances, still count in units of 100,000 instead of thousands or millions, & still eat with no utensils.

Didn't expect him to gun his $80,000 SUV, but he did. The human easily jumped in the middle of the road but the tiny, inconspicuous lunchbox didn't stand a chance. Amazingly, it still ran. There were some minor cracks, a broken spring & some bent plastic parts, but nothing that couldn't be worked around.

The lunchbox could easily have been put back on the road in its previous form, but it was a good time for the next long awaited mod. After much staring at walls, it was decided to replace the suspension with wood & replace much of the chassis with angle aluminum. This would lower the payload down to the wheels. Ideally, the wheels would have been raised higher on the existing chassis, but this would lower the battery down to the road.

Most of the chassis was ground off. The aluminum had to be ground away to make room for the motor. The aluminum ended up much heavier than ideal. There was enough room for a later step to expand the payload.

After 3 days, it was mostly complete. The suspention had to be rebuilt several times to get the measurements right. I bolts were key, but the 4-40 eye...Continue Reading
Posted by Jack Crossfire | Jun 16, 2017 @ 03:25 AM | 4,499 Views
Didn't realize Microsoft discontinued its flight simulator work in 2008. Considering the improvements in graphics hardware, the flight simulator was no longer the most immersive experience possible. What people want is immersion. The most difficult material to render accurately is human characters while the easiest is stationary landscapes. That limited the most immersive games before 1991 to flight simulators.

It was a miracle in 1991 when the 1st 1 mile resolution satellite photos started getting overlaid in the Aviator program that ran on Sun workstations. The immersion wouldn't compare with today's animated character games.
Posted by Jack Crossfire | Jun 13, 2017 @ 04:04 PM | 4,577 Views
With a 9 year old monitor & 7 year old PC, the pressure has mounted to do yet another upgrade. A modern monitor would have twice the resolution & much better color, for a lot less money. The pictures you see would look a lot better, rather than having erratic black levels & dull colors. The graphics card is 11 years old but was top of the line for it's time.

Besides the definite improvements available in picture quality, modern processors claim massive gains but no clockspeed increase. The 7 year old PC is a 3.2Ghz quad core AMD overclocked to 3.8Ghz. What does newegg show as the top end but 5 year old 4Ghz chips. The benchmarks show the Intel quad cores 3x faster & AMD octocores 2x faster than the old AMD, but benchmarks don't easily correlate with video playback.

The Macbook which runs Cinelerra 10% faster than the PC is only a 2.5Ghz Intel. 4k video editing on the top end Macs in the Apple store looked pretty slow. Performance gains may depend heavily on memory speed, which is independent of CPU speed. The 2.5Ghz Macbook may be very close to the 4Ghz top end, because of memory speed. Because of the amount of 4k video showing up, modern systems must be able to play it without hardware acceleration, at full resolution & bitrates. The old PC can decode the full 4k but only blit it to a reduced resolution window & decode it from a reduced bitrate. Heavy changes in detail make it studder.

Part of the upgrade would be returning to...Continue Reading
Posted by Jack Crossfire | Jun 09, 2017 @ 01:14 AM | 5,368 Views
Remember 4 years ago when drone delivery was just around the corner & Jeff Bezos was investing the billions in it that he now invests in Blue Origin? What about drone delivery which moves your luggage to the airport so you don't need to wait in line?
Posted by Jack Crossfire | Jun 04, 2017 @ 09:15 PM | 4,913 Views
Spacex vs spacex (3 min 22 sec)

You can infer more about the NROL-76 payload by comparing its launch against CRS-11.

The NROL-76 booster went to a much higher altitude but equivalent speed. NROL-76 was a slightly lighter payload, as shown by the faster liftoff. It had to burn a lot more fuel to land the 1st stage from the higher altitude, despite the lighter payload. CRS-11 was a 15,000 lb payload. 9000 of a Dragon mission is the Dragon system alone. The mass of the payload fairing is unknown, so it can't be directly compared to Dragon.

Estimating the mass of NROL-76 requires comparing the time it took to clear the tower to another communication satellite. SES-10 took off ever so slightly slower than NROL-76, so NROL-76 was a hair below 11,000lbs. The difference in speed was only obvious with Dragon launches, showing how the Dragon system was much heavier than a communication satellite with its fairing.

After launch, NROL-76 was detected in a 248mile circular orbit with 50deg inclination. There was no reason to go to the higher altitude besides concealing its orbit.

Falcon 9 nrol76 landing stabilized (3 min 32 sec)
...Continue Reading
Posted by Jack Crossfire | Jun 01, 2017 @ 11:49 PM | 4,916 Views
The lion kingdom's 1st motor was the Gilbert DC-3 motor. It was a marvel for a 5 year old, but it was quite difficult to get the 3V to power it in 1980. Nowadays, low voltages are everywhere, but in those days, everything ran on 120V unless it was expensive.

The motor collection has grown, over many vehicles. They're a lot more efficient than the DC-3. There are a few more little motors. Without a purpose, they're doomed.
Posted by Jack Crossfire | Jun 01, 2017 @ 12:11 AM | 5,606 Views

After 6 years of fabrication, the stratocruiser finally came out of the hanger for a fueling test. It was made out of used 747 parts, millions of fiberglass layups, & billions of latex gloves. It must be the largest piece of fiberglass in the world. Whether it's an ITS or a stratocruiser, the trend in space travel is bigger things.

In another twist, instead of marketing towards launching a single, large rocket, the plan is to launch multiple smaller rockets in a single flight. This model should allow it to avoid bad weather & reach different orbits in a single flight, but it's limited to low Earth orbit & very small payloads. The problem is they're still throwing away the rocket when a fully reusable rocket is coming increasingly closer to reality. By their forecasted 1st launch in the next 2 decades, a falcon heavy could technically achieve full reuse for small LEO payloads. The need for a gigantic airplane launching expendable rockets for these payloads would instantly end.