Streamlined?

[BP]

Core describes streamlined spacecraft as 'a wing, disc or other lifting body...' while standard refers to 'a wedge, cone, sphere or cylinder'. Now, my eye says that a Launch and a Ship's Boat are cylinders. I'm no aeronautical engineer - but a rounded nose cylinder doesn't look much like a lifting body (and Far Trader is a bit of a stretch too).

Don't get me wrong - I think they are streamlined - my personal definition being 'shaped to reduce wind (fluid) resistance'. But, by my definition all the standard shapes can be streamlined too - just don't have any blunt protrusions (i.e. mostly smooth shapes). Since standard starships (ignoring small craft) use gravitics - it seems that they shouldn't really need to be lifting bodies (or wings/discs) - only smooth enough that high winds don't slam them around... (the reason, I assume, for the -2 DM for standard designs in atmo).

Any thoughts on a better understanding/definition?

 

[FreeTrav]

I'm going to say that the Core book may have gotten it wrong, here - or rather, they oversimplified.

In my view, there are four classes of hull shape:

Antistreamlined: These are hulls that should not be brought into atmosphere, period; doing so offers a greater-than-50% chance of destruction. Good examples of these are dispersed-structure spacecraft, or anything where destructively-strong stresses will be put on joints or external protrusions. The U.S.S. Enterprise, from Star Trek, is Antistreamlined in all incarnations. Modular freighters are generally Antistreamlined.

Unstreamlined: These are hulls that should not be brought into atmosphere, but in an emergency, can survive the experience largely intact. A significant overhaul - probably more than an annual maintenance - will be required to make the hull spaceworthy afterward, and there will likely be damage caused by extreme heat from atmospheric friction. Externally-mounted sensors will be lost; gun turrets may be lost and will probably see significant damage. A Donosev-class survey ship is Unstreamlined.

Streamlined: These are hulls that can survive atmosphere, generally without serious structural damage. Some special preparations may be required. A 50-ton cutter with module is Streamlined; individually, the cutter and the module are both Unstreamlined. The Type S Scout/Courier, and the Empress Marava-class Trader, are also Streamlined. The X-boat is Streamlined, but without a maneuver drive, the question is moot; it's not likely to survive impact anyway. The X-Boat tender is Unstreamlined.

Antistreamlined and Unstreamlined hulls cannot be launched from the ground without grav lift; rocket lift will put damaging stress on the hull. Streamlined hulls can be launched with either rocket or grav, but not all streamlined hulls will necessarily be appropriate for rocket launch.

Airframe: These hulls are designed for atmospheric flight, and can even derive lift from such flight. Only normal maintenance will be required between atmospheric trips. Aircraft are by definition Airframes. The Enterprise-class Space Shuttles flown by NASA are technically Airframes, but just barely.

Disc, Wedge, Sphere, and Cone hulls are Streamlined; Block hulls are Unstreamlined, Dispersed hulls are Antistreamlined. A cylinder without a cone on the end is technically Unstreamlined, but very close to Streamlined; with the cone, it is Streamlined. Similarly a block with a wedge on the leading face.

Rounding of edges and corners isn't enough to convert from Unstreamlined to Streamlined, though it can reduce the damage caused by edge turbulence.

 

[Jame Rowe]

I'm thinking that if I ever referee a game or write up a universe, streamlining will be standard and not subject to the 10% cost increase. Yes, I am aware that this will make streamlined and standard hulls the same; indeed, that's what I want!

 

[BP]

Hey that's really excellent FreeTrav - and Jame Rowe that makes a heck of a lot of sense - we could rationalize why streamlining could cost that much more, but its really extraneous...

Almost didn't post this - thought maybe no-one else would really give a hoot! (Wrong Again - )

 

[Rikki Tikki Traveller]

I figure that Streamlined means that there are no weird protrusions on the side of the hull (like radar dishes) that would come off when you try to land.

I use the Aerofin modification from HG to make a Streamlined hull into a Lifting Body.

Remember, Streamlined is NOT like a plane. Streamlined is ungainly and difficult to land, but it can land. Aerofins are the wings/control surfaces that let a pilot land it easily.

And yes, I AM an Aerospace Engineer.

 

[dayriff]

So can you use a Streamlined hull to hop from place to place on a planet? If not, can you effectively do so by going into orbit and then landing at a different location, at considerable less efficiency than an Airframe?

Are there any standard model Traveller starships that can work as an airframe?

 

[Sir Brad]

A few the Type T looks like it is an airframe, If its not it's close enough for government work, the Type R looks like it is about as much an airframe as the shuttle, Many Varg ships like the VA, VM, VS, VF & VP are close enough if not an actual airframe. IIRC their are quite a few Winged Needle configs in the Joe fleet and the Joe ZS Scout looks like a flying wing. the Solomani go in for all kinds of configs including Aerofoiled Sources, Winged Needles and such so their is a good chance to find Airframed ships in their Fleet.

Have to go in to my Classic and Mega Libraries but I think I can find examples of Airframed ships in all the races ships.

 

[BP]

I figure that Streamlined means that there are no weird protrusions on the side of the hull (like radar dishes) that would come off when you try to land.

I use the Aerofin modification from HG to make a Streamlined hull into a Lifting Body.

Remember, Streamlined is NOT like a plane. Streamlined is ungainly and difficult to land, but it can land. Aerofins are the wings/control surfaces that let a pilot land it easily.

This is basically my view - that streamlined essentially means no excessive drag.

My layman's interpretation of 'lifting body' means that the lift 'overcomes' the drag (bernouili effect or some such comes to mind - but it's been years and I never studied aerodynamics - just dabbled in hydrodynamics at one time).

And yes, I AM an Aerospace Engineer.

Excellent - then maybe you can shed light onto wether a round nosed cylinder qualifies as a lifting body or not (assuming its not rotating or some such exotic thing and creating some kind of magnus effect or the like)!

 

[Treebore]

To me streamlined means even surfaced enough to have heat shielding in place. Or to have hulls made of material that can handle the heat of atmospheric entry.

So as long as it can handle the heat of reentry, its streamlined.

 

[atpollard]

And yes, I AM an Aerospace Engineer.

Excellent - then maybe you can shed light onto wether a round nosed cylinder qualifies as a lifting body or not (assuming its not rotating or some such exotic thing and creating some kind of magnus effect or the like)!

While I am not Rikki Tikki Traveller,

In the sense that any shape (except a sphere) can be oriented so that forward motion generates some lift, anything can be a lifting body ... but generally speaking: No, a round nosed cylinder is not a lifting body in the traditional sense of the term.

Flattening the top or bottom would go a long way towards making it a lifting body.

 

[Rikki Tikki Traveller]

I AM Rikki Tikki Traveller and I agree with ATPollard. :wink:

NO a round-nosed cylinder is not a lifting body in Traveller terms.

Also, don't forget that all of these ships have GRAVITICS. Any of them can hover, move vertically by a small amount etc. Streamlining is more for control and maximum speeds. In terms of landing, Streamlining helps overcome those high stratospheric winds.

Without considering stress... an unstreamlined ship COULD land on a planet. It might only be able to go 10 kph, but it could do it. That is not what we are considering normally and you CANNOT ignore stresses, even with gravitics.

I think that the artists drawing the various ships are more concerned with how they look than accurately reflecting Streamlined/Aerofins/Lifting Bodies; so you should take the outer appearance with a grain of salt.

In my designs, I am very careful to include Aerofins if I expect the ship to have good atmospheric performance. If it just lands and takes off, then Streamlining is good enough (like the A1 Free Trader). Other designers don't seem to be as strict with their rules as I am; but then, I really care about those things.

To me, Traveller has 3 basic hull designs:

Unstreamlined - Lot of things sticking out and that could easily break off in a strong wind.

Streamlined - Smooth surface that can land on a planet.

Aerofins - A streamlined hull that has extra features allowing high performance (relatively) maneuvering in the atmosphere (wings, canards etc).

Partial Streamlining only works in low pressure atmospheres and basically represents a design that can handle the stresses of landing but not the aerodynamic forces of landing in an atmosphere. It is a valid design for ATM 0, 1 only. Basically, I don't use it.

 

[Treebore]

Yeah, most ships I deal with are TL 12 or higher, so the Gravitics tech is pretty strong. My current game is the first I have dealt with Gravitics in the early stages, so being truly streamlined may truly matter in this game, however everything planned for the game is to take place in space vacuum.

So normally, in my "typical" games, I did not worry about streamlining too much because I just figured space ships could use their maneuver drive like big Grav Belts and move through atmosphere that way.

 

[Jame Rowe]

I figure that Streamlined means that there are no weird protrusions on the side of the hull (like radar dishes) that would come off when you try to land.

I use the Aerofin modification from HG to make a Streamlined hull into a Lifting Body.

Remember, Streamlined is NOT like a plane. Streamlined is ungainly and difficult to land, but it can land. Aerofins are the wings/control surfaces that let a pilot land it easily.

And yes, I AM an Aerospace Engineer.

This is why, IMTU, the +10% price increase for "streamlined" hulls is actually the price for aerofin bodies.

 

[BP]

Thanks a lot for all the input folks! I was working on visuals for spacecraft when I realized that my streamlined in the traditional sense craft - were not 'streamlined' in the MGT sense... and the illustrations and definitions seemed at odds!

Looking again at Atmospheric Operations in Core, streamlined is stated as '...designed to enter a planetary atmosphere, and can function like a conventional aircraft.' Where standard configuration '...is reliant on its thrusters to keep it aloft at all times and is extremely ungainly.'

This is consistent with the requirement to be a wing, disk or other lifting body - so, for me, the round nosed flying cylinder is out - with Rikki Tikki Traveller's 'grain of salt' principle overruling the traditional artists look of the Launch, Ship's Boat and Modular Cutter. In fact, the deck plans in Core indicate these ships would actually be flattened... (6-7.5 meters wide by maybe 4 meters high at the highest).

(Shuttle is the only Small Craft not listed as streamlined - though one of its roles is ferrying cargo 'from ship to surface' This woud be consistent, with say, an original Star Trek shuttle - that beloved box was hardly the picture of 'fly-able'.)

 

[Rex]

I just have my Cutters and other cylindrical "streamlined" craft, pop wings and lifting surfaces. Works for cruise missiles, iron man, the Space Battleship Yamato and the like......Not to mention things like Puddle Jumpers for my Stargate game......Really pretty easy, and that's before "Fun with Modules" begins.

~Rex

 

[Woas]

With the wonder-tech of grav plates, thrusters, inertia-dampeners and such I always wondered why there still needed to be streamlined hulls.

Does a ship need a runway to land or take off? Are ships all ships vertical take off?

 

[Rex]

If you have ever read the book "Apocalypse Troll" by David Weber, you can find a very good example as to why streamlining could be a good thing.

~Rex

 

[BP]

With the wonder-tech of grav plates, thrusters, inertia-dampeners and such I always wondered why there still needed to be streamlined hulls.

Heat and pressure would still be a problem - streamlining reduces these. Streamlining in a traditional sense is to avoid things that cause resistance - so protrusions don't break/burn off - and to avoid induced drag for better performance and control. (I'm sure that could be stated better )

In the MGT sense this also includes being a lifting body - i.e. flyable in a traditional sense... though not necessarily very well - hence the HG option for aerofins. The U.S. Space Shuttle is a lifting body design that is 'flyable' but you wouldn't want to be doing combat maneuvers in it even if it had sustainable thrust on re-entry.

Streamlining may be needed in any non-vacumm medium (atmo, fluids, plasmas) if vehicle or medium is moving fast enough to cause issues - MGT doesn't 'require' streamlining to enter these environs - only to avoid extra penalties for trying to fly in them (DM -2 I believe and Pilot checks).

MGT seems to assume that Gravitic control is not fine enough to respond well in atmo without some pilot effort ... of course, in your TU there is no need to follow this convention.

Does a ship need a runway to land or take off? Are ships all ships vertical take off?

Gravitics makes VTOL inherently cheap - and runways take up space, etc. Some small craft or spacecraft with alternate drives might require runways. MGT is quite open in its Tech Levels - the official 3I setting would generally assume VTOL - but again there would be exceptions even in the 'official' universe.

 

[Epicenter]

A Supermarine Spitfire is an airframe. An F-4 Phantom II is streamlined. See the difference?

With the wonder-tech of grav plates, thrusters, inertia-dampeners and such I always wondered why there still needed to be streamlined hulls.

I've always figured that any ship, no matter what kind of shape it is, if it has grav plates and inertial dampeners rated at 1G can land and take off from any planet.

The question is time and maneuverability.

I figure that non-streamlined ships can't go zooming out at Mach 3 or whatever their propulsion could technically move them. Landing them would take at least an hour of a slow, stately descent (perhaps more than a few hours), and taking off would take the same amount of time. A streamlined hull with the brute force of powerful enough propulsion could zip off in like 10 minutes. However, if you have the time, it's fine...

... unless you get attacked. Then you're in trouble as you can really maneuver with all that drag in something that isn't at least streamlined.

 

[Rikki Tikki Traveller]

An unstreamlined ship with Gravitics would still have problems landing on a planet with an atmosphere.

Forget the speed of the ship relative to the ground, that can be controlled. Basically, a gravitic ship could float down to the surface at 5-10kph without any problems.

The problem are WINDS. In our Stratosphere there are some very strong winds that would be cutting across the flight path of the ship. To say nothing of the Jetstream (several hundred kph winds). The winds would rip the ship apart piece by piece.

A car is partially streamlined (not streamlined in 3-D) but even cars can be tipped over in a relatively moderate wind (100 kph). Stratospheric winds are even stronger.

The shuttle craft from Star Trek are good examples of Streamlined Gravitic craft. They don't have much maneuverability, but they can fly and land. Serenity on Firefly is another example.

You don't need a lifting body if you have gravitics, so wings are only needed for control, not for lift.