Dynetics vehicles and discussion

[kerbiloid]

So many engines...
Probably they use Throttle Controlled Avionics mod.

[DBowman]

They are advertising for propellant fluid engineers and main engine pump engineers with cryo & hydrocarbon fluids experience. I'm guessing methane oxygen.

Edited May 2, 2020 by DBowman

[sevenperforce]

6 hours ago, kerbiloid said:

So many engines...
Probably they use Throttle Controlled Avionics mod.

Hah!

In all seriousness I wonder if these engines are intended to be throttleable or not. An easy way to get throttleability is to use multiple engines and shut down some of them, so they will probably be cheaper and lighter if they aren't throttleable. But if not then they'll need gimbal. If they are throttleable then they'll be able to use RCS for roll and throttle for pitch and yaw. 

6 hours ago, DBowman said:

They are advertising for propellant fluid engineers and main engine pump engineers with cryo & hydrocarbon fluids experience. I'm guessing methane oxygen.

Nice catch.

A single pump for each quartet of engines is lighter but multiple redundant pumps is more reliable.

[RCgothic]

1 hour ago, sevenperforce said:

An easy way to get throttleability is to use multiple engines and shut down some of them, so they will probably be cheaper and lighter if they aren't throttleable. But if not then they'll need gimbal. 

Not necessarily. Shut them down in pairs opposite sides of the COM. With 8 engines you then have 4 throttle settings plus off.

[sevenperforce]

42 minutes ago, RCgothic said:

Not necessarily. Shut them down in pairs opposite sides of the COM. With 8 engines you then have 4 throttle settings plus off.

That was my point. You can "throttle" by pairwise startup and shutdown, which means you don't (really) need throttleability for the landing burn. Non-throttleable engines are cheaper, lighter, more efficient, and less fault-prone. However, individual shutdowns and startups don't provide fine enough control to provide immediate pitch and yaw authority. So if they are non-throttleable, then they need gimbal, or the lander needs to rely exclusively on RCS for pointing.

If they used fixed but throttleable engines then they have to use RCS for roll but can use differential throttling for pitch and yaw. They can get roll control if they cant out some of the engines slightly, but that introduces cosine losses.

[sevenperforce]

The lander is shown landing on four engines but liftoff is with eight. Multi-engine means multi-engine-out, which I am sure NASA likes. Same concept as Falcon 9.

[Barzon]

On 5/1/2020 at 3:44 AM, sevenperforce said:

Assembly is easy enough. Keep the drop tanks attached to the LV upper stage and have the spacecraft come mate.

From what I've heard, I believe this is Dynetic's plan, and I'm 80% sure the lander is Methalox.

[kerbiloid]

They could make all eight gimbal and change the net thrust by tilting them radially all at once.

[sevenperforce]

3 hours ago, kerbiloid said:

They could make all eight gimbal and change the net thrust by tilting them radially all at once.

So basically like the new Poodle.

[RCgothic]

You'd need a heck of a lot of gimball - 35° off-axis just to get to 80% thrust.

[tater]

This lander looks to be ~3m in dia, and it's probably 4 long? ~28m³. Larger than BO/LockMart.

[kerbiloid]

5 hours ago, RCgothic said:

You'd need a heck of a lot of gimball - 35° off-axis just to get to 80% thrust.

But you need this only on landing,

[Nightside]

20 hours ago, kerbiloid said:

They could make all eight gimbal and change the net thrust by tilting them radially all at once.

This would also direct the debris plume away from the lander.

[sevenperforce]

On 5/3/2020 at 12:49 AM, kerbiloid said:

On 5/2/2020 at 7:18 PM, RCgothic said:

On 5/2/2020 at 3:18 PM, kerbiloid said:

They could make all eight gimbal and change the net thrust by tilting them radially all at once.

You'd need a heck of a lot of gimball - 35° off-axis just to get to 80% thrust.

But you need this only on landing,

Oh, so not like the new Poodle at all.

 

[tater]

Anyone need a job?

(does the star field towards the sun bother other people as much as it does me?)

[sevenperforce]

 

31 minutes ago, tater said:

Anyone need a job?

(does the star field towards the sun bother other people as much as it does me?)

Very.

Edited May 4, 2020 by sevenperforce

[tater]

https://www.sierralobo.com/sierra-lobo-inc-announces-nasas-artemis-human-landing-system-hls-award-on-dynetics-inc-team/

(hat tip @Barzon from the other thread)

[Nightside]

11 minutes ago, tater said:

 

What's up with the asymmetrical rockets being lit up in this pic? 

It looks like this to me:

OO O -

 - -  O-

[tater]

Looks like 4 per side. Top down view (O = firing):

      FRONT

X  O          X  X

X  O          O  O

 

Differential thrust for control?

 

[sevenperforce]

4 minutes ago, tater said:

Looks like 4 per side. Top down view (O = firing):

      FRONT

X  O          X  X

X  O          O  O

 

Differential thrust for control?

 

Looks like it to me.

They don't appear to gimbal. Though at this point they don't really have the engines themselves so all that is spec.

[tater]

3 minutes ago, sevenperforce said:

They don't appear to gimbal. Though at this point they don't really have the engines themselves so all that is spec.

LOL.

Still, of the 2 (3 if you count whatever Boeing was working on) "old school" landers, I like this one best.

Starship is a dark horse here, but the payoff should it work is nothing short of epic.

This lander could fly a cargo version sort of like a skycrane helicopter. Leave a hab pod, return to Gateway. Leave a dense packed cargo pod, return to Gateway. Since the ascent stage would be just the framework, more cargo to the surface would be possible.

[kerbiloid]

Why do they not just use Eagle?

Spoiler

 

[RCgothic]

Massively over-engined IMO.

[mikegarrison]

30 minutes ago, kerbiloid said:

Why do they not just use Eagle?

  Hide contents

 

Because they crash or get blown up by aliens almost every week.

[sevenperforce]

6 hours ago, tater said:

This lander could fly a cargo version sort of like a skycrane helicopter. Leave a hab pod, return to Gateway. Leave a dense packed cargo pod, return to Gateway. Since the ascent stage would be just the framework, more cargo to the surface would be possible.

Agreed. 'Twas my proposal a few months ago. Use the same architecture to support cargo drops as you use for your human ascent element; common architecture helps demonstrate function and work out kinks. Drop-tank-based architecture beats propellant transfer unless you are literally Starship.