[Laforet]

Correct, the engines were going to be retired anyway but they are keen to reuse the titanium grid fins on the boosters which cost a small fortune to make.

The core actually had older ablative grid fins made of aluminium so no great loss there[0].

[0]https://i.redd.it/l6s2bds7pl801.png

[0xTJ]

Have you seen an approximate price for those fins anywhere. I saw the interviews, but I want to know how expensive is expensive.

[nigwil_]

Platinum is USD$32K per KG, so if the platinum grid fins are 100KG, then they would cost > $300K each just for materials. With 4 per booster that might be a million dollar price tag for the grid fins.

[varjag]

The fins are titanium, not platinum. The cost of material is negligible.

[nigwil_]

Oops, you’re right my mistake

[aquadrop]

That would be $3200k for each, but they are made out of titanium, not platinum, and most of the cost is in the work, not material. I'd like to know the price too though.

[philjohn]

Yep - Titanium is notoriously difficult to work with.

[dsfyu404ed]

Titanium isn't particularly terrible to machine. Nothing is hard to machine if your budget can cover the correct tools and you machines can provide the right setting to run those tools.

Your typical mechanical engineer fresh out of school has incredibly limited experience when it comes to things that are not stupid-proof to work with (engineering programs have other priorities). They then go on to build specialized knowledge in various subjects and usually more on the design side, not the execution side. Of course someone who designs plastic molds or simulated impeller designs all day is going to create a black box around things that aren't their specialty. You don't care about how the impeller or mold is made other than knowing that it can be made, what its material properties are and knowing that actually making it involves a bunch of details you don't know so you offload it to a 3rd parts (for the same reasons someone else is having you design the impeller or the mold).

A bunch of engineers and otherwise smart people on the internet saying that titanium is like computer programmers saying residential electrical is complicated or web devs complaining about bash. It really doesn't mean much but people who have no experience with this things tend to think the people who only have a shred know what they're talking about.

It's not difficult. Most other people just know they don't know how to do it and that they don't know what they'd need to know to go about learning how.

[varjag]

It's not that difficult. The more common alloys machine relatively easily; some of the tougher ones can be a pain but not much more than other special purpose materials like Inconel.

[TomK32]

So difficult that the SR-71 leaked fuel before starts and had to be re-fueled right after take-off. https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Fuel

[votingprawn]

The SR-71 took off with a small fuel load to reduce stress and improve engine-out performance, that is why it was refuelled immediately after take-off.

The mental image of it leaking so much fuel on the ground such that it needed immediate refuelling is a myth propagated extensively on the internet.

[nsnick]

The SR-71 leaked fuel before takeoff because it needed separation distance between parts to allow for expansion. It had nothing to do with the difficulty machining titanium.

From your source: "Fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was achieved as the airframe heated up and expanded several inches.[30] Because of this, and the lack of a fuel-sealing system that could handle the airframe's expansion at extreme temperatures, the aircraft leaked JP-7 fuel on the ground prior to takeoff."

[jpitz]

The Blackbirds leaked because they had engineered gaps to allow for heat expansion.

[dsfyu404ed]

That has nothing to do with titanium and everything to do with material expansion, the design/shape of the assembly and ambient vs operating temp.

[epanchin]

KU Leuven states the grid fins at 41kg. (The same volume of material would be 193kg in platinum)

[gameswithgo]

ahh, I noticed that in the feed and was wondering why. I guess they expected it was the least likely to work? or needed the better grid fins less because of the cylindrical top

[josu]

Can they still recover them?