2300AD: Powered Landing

[SpaceBadger]

I am a bit confused about when powered landings are necessary or appropriate for interface vessels in 2300AD.

Text says that powered landings are often used by military vessels and sometimes by civilian spaceplanes. Powered landings are required when there is no atmo to glide in. Otherwise, airframe vessels usually burn 1 hour to de-orbit and then glide the rest of the way down.

The table on p.194 shows that landing times are actually increased for powered landings by airframe vessels - doubled, tripled, or quadrupled.

So why would any vessel use a powered landing when it could glide in faster and using less fuel?

Also, what exactly is a powered landing? I picture it as using engines to get down faster than a glide, then vectored thrust to slow down and land faster - but this seems contrary to the greatly increased landing times. What is it really?

 

[rgrove0172]

Im not close to my books but from your post a powered landing is one in which, in the absense of atmosphere, a ship has to fight gravity all the way down with nothing but thrust. (Think Apollo Lunar landing)

Its a tricky manuever, takes quite a bit of time and is a fuel eating monster.

 

[shaunhilburn]

I am a bit confused about when powered landings are necessary or appropriate for interface vessels in 2300AD.

Text says that powered landings are often used by military vessels and sometimes by civilian spaceplanes. Powered landings are required when there is no atmo to glide in. Otherwise, airframe vessels usually burn 1 hour to de-orbit and then glide the rest of the way down.

They must've meant one hour to de-orbit. The actual burn only takes two or three minutes. About 30 minutes after the burn the craft will encounter the upper atmosphere and begin un-powered aerobraking (the entry interface). When the control surfaces begin to respond (after 12 minutes or so), it emerges from the entry interface and will either glide the landing site or proceed under power. The actual landing mode depends on the craft; a vertical landing will always require power.

Obviously, airless bodies make aerobraking impossible, in which case the final landing descent has to be powered by rocket thrust.

Rocket burns never last more than a few minutes, regardless of the descent mode. Only the final minutes before touchdown will be under power, except for parachuting capsules and dead-gliders.

 

[SpaceBadger]

I am a bit confused about when powered landings are necessary or appropriate for interface vessels in 2300AD.

Text says that powered landings are often used by military vessels and sometimes by civilian spaceplanes. Powered landings are required when there is no atmo to glide in. Otherwise, airframe vessels usually burn 1 hour to de-orbit and then glide the rest of the way down.

The table on p.194 shows that landing times are actually increased for powered landings by airframe vessels - doubled, tripled, or quadrupled.

Hull Type	Take Off	Unpowered Landing	Powered Landing
Rocket/SSTO	2 hours	3 hours	2 hours
Standard Airframe	3 hours	1 hours	3 hours
Lifting Body Airframe	4 hours	2 hours	4 hours
Hybrid Airframe	2 hours	1/2 hours	2 hours

So why would any vessel use a powered landing when it could glide in faster and using less fuel?

Also, what exactly is a powered landing? I picture it as using engines to get down faster than a glide, then vectored thrust to slow down and land faster - but this seems contrary to the greatly increased landing times. What is it really?

 

[rgrove0172]

Errr..ok

Still think its non atmospheric landings. As you quote. Not sure what the problem is. Either time.

(Didnt mean to come off snotty in this post. Written word doesnt always convey a clear intent. Apologies if it came across wrong)

 

[shaunhilburn]

Text says that powered landings are often used by military vessels and sometimes by civilian spaceplanes. Powered landings are required when there is no atmo to glide in. Otherwise, airframe vessels usually burn 1 hour to de-orbit and then glide the rest of the way down.

A 1-hour burn is way out of line. The author meant a one-hour trip, couldn't possibly imagine thrusters burning the whole time.

The table on p.194 shows that landing times are actually increased for powered landings by airframe vessels - doubled, tripled, or quadrupled.

The table is full of numbers that were just pulled out of thin air.

So why would any vessel use a powered landing when it could glide in faster and using less fuel?

Gliders don't have the cross-range capability of powered spaceplanes; once they de-orbit, they're committed to a specific landing site come what may. Also, they can't abort a landing approach and fly around for another attempt - its do or die (sometimes die)
Spaceplanes have much greater cross-range and flexiblity. Once they emerge from entry interface, they're flown much like any other aircraft. The pilot can choosing his landing site, diverting to an alternate spaceport, even take an aerial tour.

Also, what exactly is a powered landing?

It sounds like a landing that occurs while thrust is applied from the main propulsion system. It could be a horizontal landing, as with modern airliners, or a vertical landing like helicopters, Harrier jump-jets, or even rockets landing on a plume of flame like the defunct DC-X.

I picture it as using engines to get down faster than a glide, then vectored thrust to slow down and land faster - but this seems contrary to the greatly increased landing times.

The increased landing times are BS. Any trip down from earth orbit (300 km) in a winged vehicle takes roughly one hour. STS-121 took 1 hr 9 min from de-orbit burn to wheels stop.