Jack Crossfire's blog View Details
Posted by Jack Crossfire | Nov 03, 2018 @ 05:02 PM | 2,026 Views
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Posted by Jack Crossfire | Oct 17, 2018 @ 10:03 PM | 1,935 Views
https://www.reddit.com/r/spacex/wiki...to_performance


Nifty table of all the SECO orbits. The speed & altitude can be derived from the webcasts, but the inclinations are not broadcast. Not sure how they calculated the inclination change. Even without inclinations, rough calculations based on high school geometry showed it achieving abnormally low orbits. The table confirmed those calculations were right. To recover the booster after launching a 7000kg satellite, it can only reach an elliptical 11000 miles. That's lower than GPS. It's a long way from the direct GEO insertion advertised but never used by the delta IV heavy.
Posted by Jack Crossfire | Oct 15, 2018 @ 03:59 PM | 1,571 Views
Can a PASSENGER land a PLANE? Presented by CAPTAIN JOE (15 min 51 sec)



After months of thinking about the problem, it became clear the passenger should fly manually instead of trying to reconfigure the autopilot as depicted. We're all familiar with the basic airplane controls, have played flight simulators, & can drive cars. Getting the plane to point in a certain heading & controlling speed isn't very hard.


The autopilot is a horribly complex addition. Most of the radio time is spent explaining how to use the autopilot & looking for the controls. She had to lower flaps, lower gear, & reverse thrust, despite the autolanding being engaged. A 2nd passenger could have managed the flaps & gear.
To the lay lion, manually flying would greatly increase the chances of success, but Caption Joe based the video on no doubt what the FAA recommends.
Posted by Jack Crossfire | Oct 13, 2018 @ 01:21 AM | 2,368 Views
Fascinating closeups of the tested fairing half dropped by helicopter. "LATCH +YA2", "PUSHER S/N 6", carbon fiber weaving, nitrogen bottles, are hanging out for all to see. Most important is the "NOT FOR FLIGHT !@%*@! SCRAP" written on a piece, obviously perfected from reviewing many job applications.


https://www.teslarati.com/spacex-mr-...test-practice/
Posted by Jack Crossfire | Oct 11, 2018 @ 12:35 AM | 1,495 Views
Falcon 9 launches & lands behind San Francisco (5 min 34 sec)



The plume had a similar effect as the eclipse in that it was much bigger in the sky than it looked in a photo. The flight went from Salesquota tower to the golden gate bridge. You think these events are tiny dots in the sky when in reality, they seem to take the entire sky up & they're bright. The plume was so big & bright, it felt as significant as the eclipse. Everyone else within view of it must have been as fixated on it as the eclipse.


Hopefully, someday rocket launches will be an hourly occurrence, with the bright plumes a routine sight.
Posted by Jack Crossfire | Oct 04, 2018 @ 01:22 AM | 2,230 Views
New model, showing the latest 10m thrust structure which is as wide as a Saturn V, the paint scheme you'll probably see on the real thing, a 31 engine arrangement, a window configuration which is slightly easier to model than depicted. Never perfect, but always getting better. The wings are bad, but we can see how they would interfere with a gridfin deployment on the pad. Suspected the wings & landing gear would have to be fatter than depicted to support the landing mass.
Posted by Jack Crossfire | Sep 14, 2018 @ 03:07 AM | 1,623 Views
A little more gamma reveals the blended wing body replaced by much simpler beveled wings & canards. The wings & rudder serve as landing gear. Horizontal surfaces are folding, so they can be flat to provide lift, then be a triangle to serve as landing gear. The folding might also provide aileron functionality. There are a lot more windows & they're tinted. The single piece window of BFR 1 returns. The heat shield is a simpler flat shape.

The engines seem to be the scaled down raptors that were tested 1st, but with vacuum nozzles. He decided to reuse the test engine for the upper stage, while reserving the full size engine for the lower stage. It would speed up development to not delay the ship for the full size engine. A bit disturbing to see ablative nozzles.

A bit puzzling how vacuum nozzles would allow landings on 2 different planets with different air pressures. An overexpanded nozzle is too unstable.

They could also be full sized engines with retracting nozzle extensions.
Posted by Jack Crossfire | Sep 14, 2018 @ 03:06 AM | 1,593 Views
Pay $30 for 4 new servos & the old one will start working again.


Anyways, reflowed the QFN's solder joints, & made a servo exerciser to thrash it all night. Naturally, it would never fail on the bench, but the new servos alone stood a good chance of reviving it. The last order of standard servos was 2001. They were $6 Tower Hobby branded, but shipping was much lower. Those hobbyking servos are now $5, but shipping has followed inflation.

Signs started pointing to a glitching battery connector crashing the microcontroller on the servo. The mane CPU also had glitches, but didn't lock up. The servo may just lock up under certain power glitches. After a cleaning, the $60 servo was revived & didn't crash again. So it's a lot more sensitive to electrical noise than a brushed servo. It must run at a much higher clockspeed.
Posted by Jack Crossfire | Sep 06, 2018 @ 02:42 AM | 18,388 Views
After 400 miles, the $60 brushless servo died & it went into the street. The death was intermittent, as it briefly came on again. Back on the bench, it managed to still have a fault. All the voltages were normal, with no voltage going to the MOSFET gates. Power cycling it a few times in the street didn't bring it back, but it did come back after a power cycle on the bench. Nothing that suffered mechanical wear seemed to be worn out. It was a microcontroller that had become flaky.



It's a Silicon Labs F330, 8051 core. Dave would check all the pins & try to fix it.

After all the servos, there's a real need to build a servo from scratch to last forever. The $60 one has enough useful parts to work again with a custom board, but this would be a significant investment in a rare time when the lion kingdom's time is actually worth more than a servo.



It would be a matter of removing the F330 & soldering a bare ATmega on a separate board to the 6 MOSFETs, PWM, & power. Not sure how the MOSFETs on the underside would be accessed.



Expensive, high performance servos have consistently died much faster than cheap servos. The biggest failure was the Airtronics 94761. https://www.rcgroups.com/forums/show...al#post9953885 A terrible waste from not knowing the importance of PWM frequency in tail rotor actuating.



The longest lasting might be the Tower Hobby brand from 20 years ago. Futabas are in the middle. Servos might have too many moving parts, moving too fast, in too little space.
Posted by Jack Crossfire | Aug 07, 2018 @ 04:17 AM | 1,971 Views
Amazing night views from a Falcon 9 (1 min 7 sec)


The lights of Fl*rida appear after stage separation. Then, we see lightning over the gulf of Mexico as the grid fins deploy, lit by the flickering light of the 2nd stage engine. Then, the sparks fly & the grid fins glow purple as we enter the hottest part of reentry.

https://www.rcgroups.com/forums/show...entid=11134499

It looks quite serene compared to block 3's barbeque, masking the growing spray of water in the octaweb. Can only imagine, after it hits the hottest part of reentry & the camera goes out, the water boilers are going full tilt, the grid fins are glowing, plasma is roasting the interstage & it's a pure hell.
Posted by Jack Crossfire | Jul 26, 2018 @ 05:23 AM | 1,981 Views
Falcon 9 over Pleasanton (3 min 7 sec)



There were actually very few good photos of the arc & no closeups, compared to east coast launches. The problem was fog. Everyone bent on getting good photos went close to the launchpad, under the fog. The few slackers stayed hundreds of miles away.

ISO 6400, F1.8, 1/30, 28mm for the video
ISO 400, F5.6, 30sec, 50mm, no mirror lockup for the stills

Surprised how much more interesting a video is when it shows a rocket over where you live. The USlaunchreport videos are the same white dots with the noise of a cell phone, but boring because they only show the context of a spaceport.


The color came out quite dramatic. The atmosphere & space are clearly deliniated by red & white. Was surprised how red the flame 1st was. There was no saturation effect, just a very high gamma setting, obliterating the haze. The reentry burn was another surprise. It showed it really was a Falcon 9 & the stories were real. It's another sign of a world Elon created, in addition to all the cars being Teslas.
Posted by Jack Crossfire | Jul 15, 2018 @ 04:48 AM | 2,015 Views
Finally had a go with Freecad's anaglyph feature. It's the 1st time the lion kingdom had anaglyph support in a modeling program. Maya couldn't do it, 15 years ago.
Posted by Jack Crossfire | Jul 14, 2018 @ 01:50 AM | 2,467 Views
If you held your breath, you'd last a minute on Mars without a space suit. You could feel the ground & the cold of Idaho, see an atmosphere naked eyed, but feel no air if you waved your arm. Taking your last breath would reveal a hard vacuum. You be unable to inhale & die.

Still, you could probably run out of an airlock & back in after a minute, just to feel it with your own body. A face mask could fill in while the airlock repressurized.
Posted by Jack Crossfire | Jul 13, 2018 @ 04:05 PM | 2,314 Views
As usual, the lion kingdom was the 1st to notice the heat shield isn't black, but the same color as the BFS renderings. It's a bit of fiction becoming reality & shows the BFS's color wasn't just a mockup. It's also different than the material used on the block 5 Falcon 9.


It's probably not the famous PICA derivatives but some metallic compound involving titanium. PICA was orange. It's been 80 years of trying to develop a better heat shield.
Posted by Jack Crossfire | Jul 08, 2018 @ 01:48 AM | 2,551 Views
The July 4 cruiser swore allegiance to the god emperor & chief & could make a lot of noise. It was going to be a night of fire, noise, & mane hair.


The 8 year old glow stick barely lit up. Either it expired or lion vision has deteriorated too much to see anything since using those as a kid.


The fireworks were pretty minimal. It was an overcrowded street with limited visibility & humans who were too busy yelling at each other to notice their god emperor. It was a pretty awful place for a fireworks show. The speaker wasn't needed, since they had barely audible music & the radio station didn't seem to be broadcasting the soundtrack, anymore. The FM banger came in a lot better in downtown. Then, during the 1 mile drive from the show, the $60 steering servo died. The metal gear came undone from its servo horn.

This part never got threadlock because of its tendency to crack plastic. The next idea was to threadlock just a bolt in the metal gear, let it dry, then install the servo horn. This is why you should never overhaul less than 50 miles before an important mission.
Posted by Jack Crossfire | Jun 03, 2018 @ 02:42 AM | 3,278 Views
That was a huge amount of work, intermittently, over the last 6 weeks. Still not texture mapped. Sort of gave up on something hyperrealistic, but it's still decent for a game. Don't forget griddy mcgridfin.

grid (0 min 14 sec)

Posted by Jack Crossfire | May 30, 2018 @ 11:58 PM | 3,106 Views
Drilling the holes in a space shuttle injector plate, in 1977. It was 1 of the 1st high quality photos a lion ever saw on a computer & the moment it became clear how laborious spaceships were to create. Decades later, lions realized after all that work drilling the holes, they had to plug the holes back up when they cracked.
Posted by Jack Crossfire | May 29, 2018 @ 10:00 PM | 3,028 Views
Finally cracked open the ice budget & attempted the 1st refrigerated transportation. This requires going both ways with ice blocks, significantly reducing range. 2 ice blocks were quite heavy, but it didn't show a significant increase in tire wear after 10.7 miles. Power consumption increased to 328mAh/mile. The weather started hot & got cold by the end. Sandwiched the salad between the ice blocks. The top ice block finished more melted than the bottom. The salad arrived still cold, which isn't very conclusive unless another test is done without ice, in the same weather. Ice cream definitely needs to be tested.


Whether ice on top or ice on the bottom is more effective is unclear. Most heat should get in from under the robot, but cold should travel down.
Posted by Jack Crossfire | May 26, 2018 @ 01:29 AM | 3,410 Views
Fixing the camber spread the tire wear over a larger area in the center but introduced bigger problems. It significantly reduced the range because of the higher rolling resistance & made the servo skip cogs because of the increased rolling resistance. Went back to the stock camber which wore down the inner edges & searched for a coating to resist the wear.


The solution was to glue fabric straps to the inner edges with E6000 adhesive. After hundreds of miles, they didn't wear off & the power consumption dropped to 280mAh/mile. Initially, the straps were common shoelaces, but kevlar would be the ultimate strap. The key is getting the strap to cover the entire wear pattern. If wear hits a strap edge, it'll peel off.

Earlier coatings were white electrical tape & CA glue, which instantly wore off. E6000 adhesive without fabric seemed to wear off.