Quantcast

Neil_W's half-baked design thread

The Rocketry Forum

Help Support The Rocketry Forum:

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
2,543
Reaction score
1,329
I guess that's OK?
I bet it'd be fine, it looks like it will be going plenty fast enough, so I'd guess that accelerating further wouldn't be necessary.

As it is, speed off the rail with C/C is just under 50 fps.
I bet that's fine as well, it seems to me that 50 fps is a very conservative number with plenty of margin. (Cue famous last works from my place of employment: "It's fine, just ship it.").
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
7,369
Reaction score
2,314
That would be nice, but I've not heard that it is coming, so I can't assume. Not sure why, it seems like such an obvious use for that motor.
Just for funzies, (I am not getting out much) can you sim your model with the C5-3 in the booster to see how it gets off the rail? ( :oops: for the peanut gallery, yes I know you can’t fly it that way.)
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
2,543
Reaction score
1,329
Just for funzies, (I am not getting out much) can you sim your model with the C5-3 in the booster to see how it gets off the rail? ( :oops: for the peanut gallery, yes I know you can’t fly it that way.)
Yeah, I wonder as well (as a fellow member of the peanut gallery who isn't getting out either), it does have quite a bit more punch in the first few fractions of a second.

Didn't there used to be a B14 or something like that? Now that would have been a great booster motor. POP -> Psssshshhhhhhhh
 

neil_w

Marginally Stable
TRF Supporter
Joined
Jul 14, 2015
Messages
10,670
Reaction score
3,659
Location
Northern NJ
Yeah, I wonder as well (as a fellow member of the peanut gallery who isn't getting out either), it does have quite a bit more punch in the first few fractions of a second.
Hey, I’m always up for some OR nodding around. I’ll report back on that.
Didn't there used to be a B14 or something like that? Now that would have been a great booster motor. POP -> Psssshshhhhhhhh
Yes. I believe it used the same core geometry as the C5, just with less propellant for the sustain part of the burn.

Very short intense burn, like a BP VMAX. :) Must have been a fantastic booster motor.
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
2,543
Reaction score
1,329
Just found this post, and with a video by the late Gary Byrum (post #14)

 

jqavins

Joseph Avins
TRF Supporter
Joined
Sep 29, 2011
Messages
4,685
Reaction score
1,947
Location
Howard, NY
If I limit the sustainer to a B6, I buy a little margin back, but I'd *like* to be able to fly the C/C stack, which sims to about 800 ft, plus or minus.
And increase the rod exit speed at the same time. But I get that you don't want to.

I would love to see the B14 - especially the B14-0 - come back. I've had to send my Quest Terrier-Orion two stage conversion back to the drawing board because a C6-0 or B6-0 won't get it off the rod fast enough, even with just an A8 in the sustainer. A B14-0 would solve that, as a C5-0 probably would as well. (I'll redesign for a D12-0, but there will be complications.)
 

neil_w

Marginally Stable
TRF Supporter
Joined
Jul 14, 2015
Messages
10,670
Reaction score
3,659
Location
Northern NJ
I had a 1% baked idea (really haven't even turned on the oven yet) of a pod design, possibly plasma core pods, that looked something like this:
1606706312635.png

Neither Tinkercad nor my CAD skills are really up to the task of showing this exactly like I wanted to, but it kind of conveys the idea. Would probably use 3D-printing for the curvy bits joining the nose cones and the strakes, although it would be possible (not easy) to do it with wood and paper.

No idea what to do with this yet, if anything.
 

jqavins

Joseph Avins
TRF Supporter
Joined
Sep 29, 2011
Messages
4,685
Reaction score
1,947
Location
Howard, NY
Would probably use 3D-printing for the curvy bits joining the nose cones and the strakes, although it would be possible (not easy) to do it with wood and paper.
Easier than wood and paper would be wood and carving tools. But I think you're right that 3D printing is the way to go.

I suspect it would look better with hemisphere ends (which are much better for a pressure vessel like a plasma core).
 

neil_w

Marginally Stable
TRF Supporter
Joined
Jul 14, 2015
Messages
10,670
Reaction score
3,659
Location
Northern NJ
1606744570109.png

I'm a little frustrated by all the extra unwanted object outlines being shown, but I don't think there's anything that can be done about that in Tinkercad. One of my todo items for the coming year is to properly learn Fusion 360.
 

jqavins

Joseph Avins
TRF Supporter
Joined
Sep 29, 2011
Messages
4,685
Reaction score
1,947
Location
Howard, NY
Ooh, todos for the coming year. I resolve not to join any resolution threads.

Yeah, I like it better with the rounded ends, FWIW.
 

neil_w

Marginally Stable
TRF Supporter
Joined
Jul 14, 2015
Messages
10,670
Reaction score
3,659
Location
Northern NJ
It occurs to me that if it's an engine, then it needs some sort of nozzle-y thing in the back. Sealed at both ends and separate from the main airframe (spaceframe?) doesn't make much sense, even to me.

I suppose the alternative could be that it's simply a power source positioned outside the main body, but I'm not sure that's the most logical explanation.
 

boatgeek

Well-Known Member
Joined
Dec 27, 2014
Messages
3,070
Reaction score
1,498
It occurs to me that if it's an engine, then it needs some sort of nozzle-y thing in the back. Sealed at both ends and separate from the main airframe (spaceframe?) doesn't make much sense, even to me.

I suppose the alternative could be that it's simply a power source positioned outside the main body, but I'm not sure that's the most logical explanation.
Star Trek certainly has a long canon of warp nacelles set far away from the starship body. If it's not an ion/chemical engine, then it wouldn't need a nozzle. Alternatively, one might set a radiation-generating power source far from the main hull to limit the amount of shielding needed to protect personnel. Doesn't really help at the space station, though...
 

jqavins

Joseph Avins
TRF Supporter
Joined
Sep 29, 2011
Messages
4,685
Reaction score
1,947
Location
Howard, NY
Unless it's a power generating reactor. Plasma or electricity or something is brought into the main structure through conduits contained within the pylons. Actually, I have always pictured your plasma cores as generators that feed the drive and ancillary systems that are located elsewhere. Possibly, in PD and PDII, the drives are aft of the cores and the crews forward. Using multiple cores provides more power, and placing them outboard allows for a bigger habitable volume.

(Ninjad by boatgeek's second alternative. And space stations can have all the shielding they need, since they're stationary.)
 

neil_w

Marginally Stable
TRF Supporter
Joined
Jul 14, 2015
Messages
10,670
Reaction score
3,659
Location
Northern NJ
I had in my head the nacelles from the TOS Enterprise, but indeed it seems that later models had warp nacelles that were just power/field generators, with nothing resembling exhaust.

OK, I will reconsider. Could go either way, I will work on whichever looks better. :)
 

boatgeek

Well-Known Member
Joined
Dec 27, 2014
Messages
3,070
Reaction score
1,498
I could envision an alternative physics scenario where the engine itself doesn't get much larger with more power, but the reactor volume does. [white shoe salesman voice] "You want to get up to 8.7 times C? We can do that by bolting on two more nacelles and upgrading the injectors, for the low, low price of..."
 

jqavins

Joseph Avins
TRF Supporter
Joined
Sep 29, 2011
Messages
4,685
Reaction score
1,947
Location
Howard, NY
Even the TOS nacelles didn't have exhaust. Though some artists' renderings seemed to, those were from artists who didn't get it.
1606757444317.png
 

neil_w

Marginally Stable
TRF Supporter
Joined
Jul 14, 2015
Messages
10,670
Reaction score
3,659
Location
Northern NJ
Even the TOS nacelles didn't have exhaust. Though some artists' renderings seemed to, those were from artists who didn't get it.
Did not know that! (although I never thought about it much)

It makes sense that a ship capable of FTL interstellar travel wouldn't ever be able to rely on any sort of traditional propulsion system. In the Star Wars universe, the sub-light drives all have nozzles, but seem not to eject mass, just light from some sort of internal glowing energy source. I've not looked deep enough to see any obvious visual evidence of the hyperdrives on the various ships. The TIE fighters have no visible means of propulsion at all, which is one of the things I love about them (I tend to think of the TIE fighter as one of the greatest, if not *the* greatest, sci-fi ship designs of all time).

Our rocket, on the other hand, must have a tradition motor. In doing sci-fi designs we must either integrate it into the design, or just ignore and/or de-emphasize it. Ultimately there are no rules, only care about what looks good. Usually it does help for it to be at least somewhat logically consistent, but it is not a strict requirement.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
7,369
Reaction score
2,314
The TIE fighters have no visible means of propulsion at all, which is one of the things I love about them (I tend to think of the TIE fighter as one of the greatest, if not *the* greatest, sci-fi ship designs of all time).
Interesting quote from Wikipedia

In 2018, a number of Star Wars starfighters had their aerodynamic abilities tested using the Autodesk Flow Design virtual wind tunnel program. Of those studied, the TIE Fighter scored the worst with a drag coefficient of .98, which is only slightly better than a brick.

Of course, it was designed for use in space, but if I remember it right they fight it out with X-Wings just above the beaches in Rogue One.
 

boatgeek

Well-Known Member
Joined
Dec 27, 2014
Messages
3,070
Reaction score
1,498
Interesting quote from Wikipedia

In 2018, a number of Star Wars starfighters had their aerodynamic abilities tested using the Autodesk Flow Design virtual wind tunnel program. Of those studied, the TIE Fighter scored the worst with a drag coefficient of .98, which is only slightly better than a brick.

Of course, it was designed for use in space, but if I remember it right they fight it out with X-Wings just above the beaches in Rogue One.
High drag and a high thrust engine might be pretty hot in an atmospheric dogfight. IIRC, a good pilot the old Harrier jump jets could beat significantly newer fighters in a dogfight by basically stopping and starting again, letting the fast jets go by and then suddenly being right on their tail. Of course, that never showed up in Rogue 1, but that just shows their lack of imagination of how it would actually work vs. how air combat was supposed to look.
 

neil_w

Marginally Stable
TRF Supporter
Joined
Jul 14, 2015
Messages
10,670
Reaction score
3,659
Location
Northern NJ
Of course, it was designed for use in space, but if I remember it right they fight it out with X-Wings just above the beaches in Rogue One.
IMHO, the ability of sci-fi spaceships to somehow fly in the atmosphere without any sort of aerodynamics is one of the most ridiculous. The other is the ability to maintain internal artificial gravity under (apparently) all conditions, including power failures, and also neutralize all G-forces from the various extreme maneuvers the ships are doing all the time. Of course, the gravity business is sort of a necessary compromise to facilitate scenes inside ships, but there is no good reason I can think of why TIE fighters should be flying around the atmosphere and even landing. Yeesh.
 

lakeroadster

Lonewolf.... No Club
Joined
Mar 3, 2018
Messages
2,325
Reaction score
1,143
Location
Central Colorado
Interesting quote from Wikipedia

In 2018, a number of Star Wars starfighters had their aerodynamic abilities tested using the Autodesk Flow Design virtual wind tunnel program. Of those studied, the TIE Fighter scored the worst with a drag coefficient of .98, which is only slightly better than a brick.

Of course, it was designed for use in space, but if I remember it right they fight it out with X-Wings just above the beaches in Rogue One.
But with enough power...drag coefficients aren't really a concern. Tim Allen made a career out of that.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
7,369
Reaction score
2,314
IMHO, the ability of sci-fi spaceships to somehow fly in the atmosphere without any sort of aerodynamics is one of the most ridiculous. The other is the ability to maintain internal artificial gravity under (apparently) all conditions, including power failures, and also neutralize all G-forces from the various extreme maneuvers the ships are doing all the time. Of course, the gravity business is sort of a necessary compromise to facilitate scenes inside ships, but there is no good reason I can think of why TIE fighters should be flying around the atmosphere and even landing. Yeesh.
Zero G is hard to realistically simulate with real actors. I think Apollo 13 made the best effort using the Air Force KC-135 Vomit Comet,

From https://www.space.com/37942-vomit-comet.html
According to NASA, one of these airplanes, KC-135A, performed more than 58,000 parabolas, and averaged 3,800 parabolas and 300 flight hours per year before it made its last microgravity flight, on Oct. 29, 2004.

The airplane also made a Hollywood appearance: It was used to film weightless scenes in the movie "Apollo 13." According to an article on Space.com's sister site Live Science, set designers created a spacecraft interior adapted to the inside of the airplane. Then, the cameras captured short, seconds-long snippets on film. Director Ron Howard leased the aircraft for six months to achieve the shots of weightlessness that viewers see in the film.

Space Cowboys (great fun film for us middle aged BARS.) used Computer Animation for many of its scenes

From. https://mauiwatch.com/2020/08/a-rons-film-rewind-presents-space-cowboys-20th-anniversary/

The third act of the film (the time they spend in space), were entirely done by computer graphics and the actors’ faces were added in digitally.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
7,369
Reaction score
2,314
It is by mindsim alone I set my mind in motion. It is by the juice of Safu thoughts aquire speed the lips aquire stain the stain becomes a warning. It is by mindsim alone I set my mind in motion.
Like a circle in a spiral....
 

kuririn

BARGeezer
TRF Supporter
Joined
Oct 3, 2016
Messages
5,460
Reaction score
3,052
Location
Hawaii
It is by mindsim alone I set my mind in motion. It is by the juice of Safu thoughts aquire speed the lips aquire stain the stain becomes a warning. It is by mindsim alone I set my mind in motion.
“I must not fear.
(instability).
Fear is the mind-killer.
Fear is the little-death that brings total obliteration.
I will face my fear.
I will permit it to pass over me and through me.
And when it has gone past I will turn the inner eye to see its path.
(Straight and vertical.)
Where the fear has gone there will be nothing.
Only I will remain.”
(And my cool design.)
~ Bene Gesserit Litany Against Fear, Dune series of books, written by Frank Herbert
 

JoePfeiffer

Well-Known Member
Joined
Jun 15, 2013
Messages
148
Reaction score
122
Did not know that! (although I never thought about it much)
I remember in junior high figuring out thrust from the nacelles would just force the ship to go in a circle. It was years and years before I found out they were field generators. Even "impulse power" turned out to be some sort of gravity manipulation.
 
Top