Testing booster recovery equipment is not like testing other equipment as booster recovery is of no advantage to the customer. If you test the fins and they fail the test what do you do? You have to choose between delaying the customer's launch (if possible) and expending the booster.
Quote from: Stan-1967 on 12/18/2018 11:42 pmThe grid fins deploy when S1 is in free fall, and they are also carry some not insignificant mass. I wonder if the hydraulics do not have power to deploy them when under 1g, therefore they can’t be ground checked when S1 is vertical under its own internal power. Deployment also looks s bit non linear, like it is spring loaded or something. Actual control inputs are rotational, and give 2 axis control only.Afair, Falcon9 used to retract the fins on its own after landing, during saving procedure. They also extended them under 1 G on F9RDev1 flights, although those were lighter aluminum fins and a dev vehicle.It could be something mundane like physically being in the way of the TE that prevents a full actuation test on the pad. Or they just didn't bother since the system wasnt mission critical until now.
The grid fins deploy when S1 is in free fall, and they are also carry some not insignificant mass. I wonder if the hydraulics do not have power to deploy them when under 1g, therefore they can’t be ground checked when S1 is vertical under its own internal power. Deployment also looks s bit non linear, like it is spring loaded or something. Actual control inputs are rotational, and give 2 axis control only.
Maybe that check could be done after the partial retraction of the TE?
.... ( note SpaceX does use springs for S1/S2 separation, & fairing sep. They like springs.) ...
Quote from: Stan-1967 on 12/21/2018 02:50 am.... ( note SpaceX does use springs for S1/S2 separation, & fairing sep. They like springs.) ...I'm pretty sure stage separation is pneumatic. (High pressure helium if I'm not mistaking)
Inside that 21-inch-by-18-inch-by-11-inch box is a self-contained factory using the near-weightlessness of space to pull high quality optic fiber from highly technical glass....As Saad talked about the project last week on the upper floors of Thorlabs' headquarters on Sparta Avenue, more than 250 miles higher still, astronauts were installing the third box in a series of four that make up this stage of experiments.The third box was delivered to the ISS on Dec. 8, aboard the SpaceX-16 mission and returns to Earth early next year when the docking vehicle leaves the station. A fourth box will be delivered aboard SpaceX-17, due to launch in March.Saad heads up the Thorlabs team that is working with a team from a California-based company, Made in Space, which is providing the mechanics of the glass-pulling "factory" in the box....The glass being used in the ISS experiments is made from a group of fluoride compounds.The difference between glass fiber made from silica and fiber drawn from fluoride is the wavelengths of light that can be transmitted along the fiber....Saad said the first two flights of the production box on ISS did not produce any fiber because of mechanical issues....The result was blobs of glass, rather than strings of glass.In this third box, the glass is pulled along and it's hoped strands of fiber will result. The box has three "pre-forms," specific size, shape and weight pieces of pure glass, which can be pulled into a total of 1.5 kilometers (0.93 miles) of optic fiber....
(Snip)I'll defend myself a bit & say I think it's fair to consider a pneumatic pusher as a type of spring. :-) My original thinking was however that it was mechanical, so I erred in that. To the points I made, using the existing high pressure helium to deploy the heavy grid fins seems consistent with a favorable trade against oversizing the hydraulics for ground test or deployment under gravity.
Titanium grid fins are not “heavy” in free-fall. 😉They are massive, but the power to deploy them is inverse to the speed of deployment. (Even under 1g)However, the power to actuate them against the airstream must be huge. The scaling of the hydraulic actuation system is unlikely to be effected by deployment.
The last line in the article should really say:CRS-17 is the next Dragon ONE mission to the ISS, currently scheduled for March.
Quote from: ejb749 on 01/14/2019 04:22 amThe last line in the article should really say:CRS-17 is the next Dragon ONE mission to the ISS, currently scheduled for March.I like your optimism.
Will DM-1 be the next splashdown for SpaceX? Is CRS-16 the last Dragon1 splashdown before the first Dragon2 splashdown? If so, what a sweet 16.
Quote from: tyrred on 01/15/2019 08:43 amWill DM-1 be the next splashdown for SpaceX? Is CRS-16 the last Dragon1 splashdown before the first Dragon2 splashdown? If so, what a sweet 16.You need to add the two test flights plus the pad abort test, but then subtract CRS-7, which had a rather harder splashdown than usual.So there have been 18 good splashdowns and one not so good so far. Not counting the various parachute tests, of course.
Re: CRS-16 splashdown and return to port at nearly the same time as...Iridium Next Flight 8 1st stage return to port:Are both assets returning to the same dock or dock area? If so, might they be there simultaneously?That would be a great photo-op!
Quote from: zubenelgenubi on 01/13/2019 07:51 amRe: CRS-16 splashdown and return to port at nearly the same time as...Iridium Next Flight 8 1st stage return to port:Are both assets returning to the same dock or dock area? If so, might they be there simultaneously?That would be a great photo-op!Tweet in NSF forum post here contains video of such a view!
