Author Topic: Titanium Falcon  (Read 10086 times)

Offline biosehnsucht

  • Full Member
  • *
  • Posts: 181
  • Liked: 44
  • Likes Given: 52
Re: Titanium Falcon
« Reply #20 on: 08/18/2017 07:41 AM »
At first I didn't notice the day of month or year and was like "well, duh, we already know they switched to titanium grid fins".

You totally called that.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6061
  • Everyplaceelse
  • Liked: 788
  • Likes Given: 4896
Re: Titanium Falcon
« Reply #21 on: 08/18/2017 07:46 AM »
But having booster and upper stage made of different materials eliminates any production synergism.  it would require separate tank production lines.
Indeed.

Conceptually it would duplicate the Saturn V architecture, trading performance for cost, but with structure changes rather than fuel changes.  :(

That would be a re-visiting of the design-for-minimum-cost paradigm, with a big simple booster and the higher performance reserved for the US.

While theoretically attractive in reducing the overall recurring costs of a govt programme (the really expensive tech gets used where its weight is 1:1 ) I think SX have found that commonality of structures, propellants and engines across both stages has been much more productive.

And SX have shown themselves quite sensitive to the costs of splitting an LV design by fuel, materials or engine design
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6061
  • Everyplaceelse
  • Liked: 788
  • Likes Given: 4896
Re: Titanium Falcon
« Reply #22 on: 08/18/2017 08:03 AM »
This isn't a Cold War project like the B-70 (which was ultimately too expensive to produce more than the 3 airframes anyway).

Only two XB-70s were built (the second crashed, the first is in the USAF museum in Dayton, OH), and they were almost entirely made of stainless steel, with titanium just in the most critical parts.

The SR-71, on the other hand...
AIUI Titanium was ruled out of the XB70 on cost and availability grounds. It's payload was about 10x that of the A12/SR71 and even then the CIA set up front companies to buy the raw Titanium  from Russia.

Books on the SR71 say that while Titanium was being used a bit in the US at the time,  Kelly Johnson's team had to set up quite a lot of the infrastructure themselves. [EDIT and learn things like you can't use felt tip pens on the alloy as they will eat through it (what ??? ) likewise IIRC Chrome in Chrome Vanadium steel tools embrittled it. It seems like real EE Smith territory (where the hero has to build the tools, that build the tools, to build the machinery that's actually needed  :(  )  ]

Either no one had experience of doing what they wanted or doing it on the scale they wanted to do it.

What was amazing about the XB70 (apart from its shockwave rider aerodynamics) was how NAA did it with a relatively pedestrian 17/7 steel alloy by using honeycomb panels, although QC on them seems to have been a nightmare.  :( [EDIT in principal, with pervasive use of shop floor CNC and real time monitoring of mfg processes  they would be much more consistently reproducible. Provided you could live with a vehicle with an enormous RCS  :( ]

People seem to forget that people have already built LV's with steel tanks and did so up to the Atlas III, while Centaur is still a steel tank design.

No one has AFAIK built a Titanium stage, although it's relatively easy to diffusion bond.
To play to its strengths you'd need to decompose a design into "primitives" you could use standard Ti sections for (which actually have quite tight dimensional tolerances)like the "slicing" software used to analyze CAD drawings to drive a 3D printer , then construct a layup of steel sections to support the structure before canning it, evacuating the can and sticking it in a large heated press. 

BTW IIRC the Atlas steel tanks were about 1-2mm thick ("no thicker than a Dime" was the phrase) in the SS301 FH temper. This is roughly 1/10 the maximum thickness that modern FSW systems can cope with in steel (not just Aluminum), so well within the current SoA for FSW but with near 100% weld efficiency.
« Last Edit: 08/18/2017 08:38 AM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online LouScheffer

  • Full Member
  • ****
  • Posts: 1551
  • Liked: 1734
  • Likes Given: 197
Re: Titanium Falcon
« Reply #23 on: 08/18/2017 01:09 PM »
Might make sense to make /portions/ of Falcon out of Titanium. Like the grid fins or maybe parts of the thrust structure. To enhance durability and reduce the amount of TPS you need.

But I don't think they'll make the tanks (etc) out of it. Hard to work, not generally as good structure/mass (the lower density of aluminum helps for compressive structures in ways beyond pure strength/weight ratio because of reduced buckling).
Called it.
For historical interest only, mvpel may have called it first.  The idea was certainly rattling around:
Titanium grid fins for supersonic rocket manufactured

Quote from: LIN Industrial
3D printed plastic grid fins we currently use can't withstand the dynamic pressure and heating at supersonic. That's why we have started manufacturing titanium grid fins. They are cut from a single piece of titanium with a CNC machine:



Offline tdperk

  • Full Member
  • **
  • Posts: 225
  • Liked: 70
  • Likes Given: 21
Re: Titanium Falcon
« Reply #24 on: 08/18/2017 05:18 PM »

Well, the MCT is (purportedly) more than just a second stage, so comparing BFR to MCT is less like comparing Falcon 9's stage 1 to stage 2 and more like comparing Falcon 9's stage 1 to the Dragon 2.

No, it is still the same comparison.  The MCT will have a propulsion system with elements common to the booster.

Which in no way requires identical tankage, or even concept of how that tankage is to be made.

Offline dorkmo

  • Full Member
  • ****
  • Posts: 643
  • Liked: 292
  • Likes Given: 758
Re: Titanium Falcon
« Reply #25 on: 08/18/2017 09:33 PM »
Might make sense to make /portions/ of Falcon out of Titanium. Like the grid fins or maybe parts of the thrust structure. To enhance durability and reduce the amount of TPS you need.

But I don't think they'll make the tanks (etc) out of it. Hard to work, not generally as good structure/mass (the lower density of aluminum helps for compressive structures in ways beyond pure strength/weight ratio because of reduced buckling).
Called it.
For historical interest only, mvpel may have called it first.  The idea was certainly rattling around:
Titanium grid fins for supersonic rocket manufactured

Quote from: LIN Industrial
3D printed plastic grid fins we currently use can't withstand the dynamic pressure and heating at supersonic. That's why we have started manufacturing titanium grid fins. They are cut from a single piece of titanium with a CNC machine:




shout out to dorkmo for starting that clairvoyant thread :P
« Last Edit: 08/18/2017 09:34 PM by dorkmo »

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6061
  • Everyplaceelse
  • Liked: 788
  • Likes Given: 4896
Re: Titanium Falcon
« Reply #26 on: 08/21/2017 07:41 AM »
shout out to dorkmo for starting that clairvoyant thread :P

Consider yourself shouted out.

"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline darkenfast

  • Member
  • Full Member
  • ****
  • Posts: 735
  • Liked: 370
  • Likes Given: 719
Re: Titanium Falcon
« Reply #27 on: 08/21/2017 08:16 AM »
Every time Titanium comes up in this forum, I think of the line in the early part of "Destination Moon", where the rocket-building industrialist barks into his telephone: "Too heavy! Try Titanium!".

On a slightly more factual note, I was always impressed that the Soviet Union managed to build whole large submarine pressure hulls out of the stuff.   None of which is germane to Falcon 9, of course!

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6061
  • Everyplaceelse
  • Liked: 788
  • Likes Given: 4896
Re: Titanium Falcon
« Reply #28 on: 08/21/2017 09:44 AM »
On a slightly more factual note, I was always impressed that the Soviet Union managed to build whole large submarine pressure hulls out of the stuff.   None of which is germane to Falcon 9, of course!
Rocket propellant tanks are also pressure vessels and welding Titanium (which I think is how the Russians did it) is pretty tough, although they also seem to have worked on diffusion welding quite a bit, especially in devising clever ways to build and operate on site vacuum chambers.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Karloss12

  • Full Member
  • *
  • Posts: 198
  • Liked: 28
  • Likes Given: 0
Re: Titanium Falcon
« Reply #29 on: 08/22/2017 09:15 PM »
When comparing the running costs of a reusable Aluminium core vs Titanium core the only difference is the cost of fuel.
The 20% heavier Aluminium core will need to burn 20% more fuel.  If Elons statement that the cost of fuel per launch is $500k is correct then each launch will be a total of $100k less expensive.
If the fabrication of a titanium core costs $20mil more than an Aluminium core then the small $100k saving per flight will never pay off the $20mil sunk into the cores fabrication.

Offline Stan-1967

  • Full Member
  • ****
  • Posts: 467
  • Denver, Colorado
  • Liked: 247
  • Likes Given: 162
Re: Titanium Falcon
« Reply #30 on: 08/22/2017 09:25 PM »
It is not the cost of fuel that would drive any use of titanium.  I think of the following drivers.
1.  Does titaninum enables more re-uses to ammortize the full cost? ( this covers safety margins & more re-use margin)
2.  Does it enables less refurbishing effort that can be monetized?
3.  Does it increase safety margins that might affect insurance rates?

Titanium grid fins definately met #1 & #2.  Would a Ti core do the same?

Online russianhalo117

  • Senior Member
  • *****
  • Posts: 3806
  • AR USA / Berlin, DE / Moscow, RF
  • Liked: 737
  • Likes Given: 448
Re: Titanium Falcon
« Reply #31 on: 08/22/2017 10:37 PM »
This isn't a Cold War project like the B-70 (which was ultimately too expensive to produce more than the 3 airframes anyway).

Only two XB-70s were built (the second crashed, the first is in the USAF museum in Dayton, OH), and they were almost entirely made of stainless steel, with titanium just in the most critical parts.

The SR-71, on the other hand...
Actually they are XB-70A's the original XB-70 programme ended when the B-70 programme was cancelled. XB-70A research programme replaced the XB-70 development programme: http://www.boeing.com/history/products/xb-70-valkyrie.page

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6061
  • Everyplaceelse
  • Liked: 788
  • Likes Given: 4896
Re: Titanium Falcon
« Reply #32 on: 08/23/2017 07:17 PM »
Actually they are XB-70A's the original XB-70 programme ended when the B-70 programme was cancelled. XB-70A research programme replaced the XB-70 development programme: http://www.boeing.com/history/products/xb-70-valkyrie.page
Interesting point from that webpage.

The landing gear for the XB70 weighed 5.4 tonnes for a GTOW of 542Klb (which comes to 246363 Kg, not 245,847 )
That means it's 2.197% of GTOW.

That's relevant because the SEI study for the SABRE based TSTO reckoned you needed at least 4% for a similar sized vehicle.

Which demonstrates the difference between (common) state of practice and state of the art (and IIRC the B58 was even lower).

Unfortunately this has limited relevance to a VTOL Titanium rocket, given that a)Most of the XB70A was steel honeycomb and b)the landing legs only deploy on landing, when it will be realistically <10% of stage takeoff weight (probably by quite a wide margin).   :(
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 27025
  • Minnesota
  • Liked: 6915
  • Likes Given: 4879
Re: Titanium Falcon
« Reply #33 on: 08/24/2017 12:27 PM »
Yeah, it's definitely possible to get lower than 4% weight for legs. This is a point HMXHMX often makes.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6061
  • Everyplaceelse
  • Liked: 788
  • Likes Given: 4896
Re: Titanium Falcon
« Reply #34 on: 08/24/2017 04:11 PM »
Yeah, it's definitely possible to get lower than 4% weight for legs. This is a point HMXHMX often makes.
True but that misses the point.

It's basically a time honored heuristic of aircraft design.

But AFAIK there is no equivalent heuristic for VTOL, although I think Armadillo and Masten have both done enough to have some number in mind depending on wheather you want it to stand on them fully fueled or only deploy when the tanks are nearly empty.

That's clearly going to make a big difference to what mass you need to assign given loads.

IDK, for a fully fueled VTO stage 4% might be too low, while for gear that's only going to be needed during it's near empty landing it's grossly high, but by how much?
"Vertical Landing" (as a thing) is not going to go away any time soon.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline envy887

  • Senior Member
  • *****
  • Posts: 2707
  • Liked: 1248
  • Likes Given: 780
Re: Titanium Falcon
« Reply #35 on: 08/24/2017 06:08 PM »
Yeah, it's definitely possible to get lower than 4% weight for legs. This is a point HMXHMX often makes.
True but that misses the point.

It's basically a time honored heuristic of aircraft design.

But AFAIK there is no equivalent heuristic for VTOL, although I think Armadillo and Masten have both done enough to have some number in mind depending on wheather you want it to stand on them fully fueled or only deploy when the tanks are nearly empty.

That's clearly going to make a big difference to what mass you need to assign given loads.

IDK, for a fully fueled VTO stage 4% might be too low, while for gear that's only going to be needed during it's near empty landing it's grossly high, but by how much?
"Vertical Landing" (as a thing) is not going to go away any time soon.

The F9 is about 27 tonnes (or tons?) at landing according Hans K. The legs are about as much as a Model S (about 2,000 kg) according to Elon. So that's between 7.4% and 8.1% of the landing mass, depending on whether Hans meant short or metric tons.

Either way, a lot more than 4%...

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6061
  • Everyplaceelse
  • Liked: 788
  • Likes Given: 4896
Re: Titanium Falcon
« Reply #36 on: 08/24/2017 07:17 PM »
Yeah, it's definitely possible to get lower than 4% weight for legs. This is a point HMXHMX often makes.
True but that misses the point.

It's basically a time honored heuristic of aircraft design.

But AFAIK there is no equivalent heuristic for VTOL, although I think Armadillo and Masten have both done enough to have some number in mind depending on wheather you want it to stand on them fully fueled or only deploy when the tanks are nearly empty.

That's clearly going to make a big difference to what mass you need to assign given loads.

IDK, for a fully fueled VTO stage 4% might be too low, while for gear that's only going to be needed during it's near empty landing it's grossly high, but by how much?
"Vertical Landing" (as a thing) is not going to go away any time soon.

The F9 is about 27 tonnes (or tons?) at landing according Hans K. The legs are about as much as a Model S (about 2,000 kg) according to Elon. So that's between 7.4% and 8.1% of the landing mass, depending on whether Hans meant short or metric tons.

Either way, a lot more than 4%...
Well that's intriguing. Definitely not my instinct would have been. So 7-8+% of gross landing weight.

I'm pretty sure one of the (theoretical) benefits of VL was expected to be it's very low landing gear penalty  compared to the wheeled landing gear on HTOL or VTOHL systems.

This suggests that has not really worked out IRL.  :(

Perhaps the new on deck grabber robot will help?
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline guckyfan

  • Senior Member
  • *****
  • Posts: 6384
  • Germany
  • Liked: 1608
  • Likes Given: 1414
Re: Titanium Falcon
« Reply #37 on: 08/24/2017 07:59 PM »
Well that's intriguing. Definitely not my instinct would have been. So 7-8+% of gross landing weight.

I'm pretty sure one of the (theoretical) benefits of VL was expected to be it's very low landing gear penalty  compared to the wheeled landing gear on HTOL or VTOHL systems.

This suggests that has not really worked out IRL.  :(

Perhaps the new on deck grabber robot will help?

The dry mass penalty for horizontal landing is the added structural mass needed for different load paths and the wings. In total much more mass, even if the landing gear itself would be lighter.

Offline livingjw

  • Full Member
  • **
  • Posts: 293
  • Liked: 285
  • Likes Given: 126
Re: Titanium Falcon
« Reply #38 on: 08/24/2017 11:49 PM »
That much weight for the landing gear just seems way to high. Just my opinion.

John

Offline Apollo100

  • Member
  • Posts: 25
  • Liked: 0
  • Likes Given: 0
Re: Titanium Falcon
« Reply #39 on: 08/25/2017 01:28 AM »
No comments yet about the ability/complexities to FSW Ti?

Tags: