AZHRAE/Space Planes question

[Tellon]

I was playing around with a VTOL space plane design -- mostly TL A -- but due to the "variable" TL's I use -- this world happens to have TL for electronics/computers -- so that area is TL 12 stuff -- )

so using a TL 8 AZHRAE and just shaking my head at the weight of the Turbojet/Ramjet fuel and how have the design is 2/3rds fuel easily .. for a PLANE! and I have 1 day of fuel for the PNR and 30 min (yes you read that right -- 1/2 hour) for each TJ/RJ/Rkt fuel to get my space-plane off the ground and to the Highport to deliver the cargo and then head back down for another load.

since the TJ delivers less thrust -- I have to "wait" until fuel burns off so I can get the thrust up to past 1G, so the RJ then can go at least the 1.5G -- and the Rkt then goes at least 2 G to get to the Highport.

so -- 100 tons/kl of cargo and 30 passengers per load --

for a 1400kl spaceplane? (basically the same size as the Shuttle)
----

So my question

Have any of you folks designed a spaceplane .. say TL 8,9,A -- and what have you folks gotten for cargo/passengers per load?

*note: at least the fuel is cheap enough to make the trip "somewhat" profitable -- but man.

 

[E.D.Quibell]

So my question

Have any of you folks designed a spaceplane .. say TL 8,9,A -- and what have you folks gotten for cargo/passengers per load?

*note: at least the fuel is cheap enough to make the trip "somewhat" profitable -- but man.

Robert Dean to the rescue!

http://traveller.mu.org/archive/DeanFiles/SHIP0077.HTM

I hope this helps, and please post the design when you've finished.

Best Regards,

Ewan

 

[aramis]

Keep in mind: Rob used MT rules; TNE/T4 will have significantly different performance.

 

[saundby]

I'm far less skilled at designing with Traveller rules than many others here, but I can fill in some RL info that may be of use to you. Doing retro-designs using RL design rules is a bit of a hobby of mine, and a useful one since it looks enough like work nobody minds if I do it during "hurry up and wait" periods at work.

For control systems, take a look at the Titan core engines. The control system is a complex valve that is essentially a hydraulic computer. The whole engine is a sort of Victorian clockwork mechanism. It's extremely cool. Both the design of the control system and the design tools to create it could be pushed back a century without being anachronistic. You'd just need to add an anachronistic knowledge of propellants, thrust chambers, and injection systems. Nothing a dedicated mad scientist couldn't come up with on their own with a decade or two's work, plenty of funding, and a few assistants to blow up.

http://themilitarystandard.com/missile/titan2/startsequence.php

There's an engine called the Aeroturbo Ramjet or ATR (sometimes mistakenly called an Air Turbo Ramjet, I think that's what they call it on Wikipedia) that may be able to reduce your SSTO's engine mass and volume some. It's been solid, deployable tech since at least the mid 60's, but in RL the right job has never come along. It'll take you from a standing start to Mach 5 with one engine that's simpler than a Turbojet. It's basically a ramjet with a turbine on the front. It needs a start cartridge and gas generator (slow, low pressure rocket in a bottle) to get started, then it feeds itself. Easier to manufacture than a regular jet engine, one moving part, they could have built these in the 30's if they'd known how. All the finesse is in the shape of the parts.

Liquid Air Cycle Engines (LACE, SABRE) are all firmly TL A, IMO. There are just too many variables to deal with putting a real-time propellant production and conditioning plant on the aircraft.

At low TLs, it's worth throwing away engines to reduce mass in the design that would be required for re-use or longer lifetimes. So for your final boost I'd recommend throwaway-style booster rockets to get from thin air to orbit. Treat them like non-reloadable JATOs. This would make a plane that would use ATRs to get from a standing start to Mach 5 and thin air. The boosters would then push it into orbit. (To be honest, a second stage "cargo missile" to orbit with the plane returning to the ground would be far more cost-effective.)

Realistically, getting a payload mass fraction of even a few percent is really tough, and can only really be managed by eliminating a lot of reusability and safety margin until you get to TL A. For the game, I'd allow a payload mass fraction of up to 8 or 10% with a TL9 vehicle. 30 people -and- 100dtons of cargo is a huge payload for a craft like this. If you can get it to do that within the game design rules, I'd say you're doing fine.

Hopefully some of this will be useful for you.

 

[Tellon]

Robert Dean to the rescue!

http://traveller.mu.org/archive/DeanFiles/SHIP0077.HTM

I hope this helps, and please post the design when you've finished.

Best Regards,

Ewan

Sweet -- thx!!! ..

and thx for that tidbit about MT Aramis ..

 

[Tellon]

Here is a space plane for you guys who wanna see some TNE stuff .. it's an exploration shuttle using AZHRAE ..

thx for the BARD

http://www.downport.com/bard/bard/sara/sara4000.html