Lakeroadster's Cygnus Probe Ship

[jqavins]

OR *will*, to the best of my understanding, model the base drag' contribution to Cd. What it will *not* do is model the effect of the base drag on Cp.

And that's why

That will make the model even draggier, so ignore the altitude results.

 

[neil_w]

And that's why

Yes, that is always true: the base drag correction hack is *exclusively* for CP calculation, not for flight simulation.

 

[lakeroadster]

Thanks! Looks like it's back to the drawing board for revision 03

Probe Ship | Disney Wiki | Fandom

"The Probe Ship is a small scout vessel that appeared in the 1979 film The Black Hole."

View attachment 501231

Here's the changes, based on the Disney Model. The "nose cone" and upper rings have been changed.

As you can clearly see in the comparison below, the lower conical section on my version is shorter than the Disney model, and is similar to the Estes art from their catalog. I took a look at stretching that section, but I just didn't like the looks of it.

IMO, Estes did it better. Kind of a Mars Lander meets Cygnus Probe. I'll follow the lead of Estes.

Rev 02 is a go for the build!

 

[lakeroadster]

The Build Begins

Cutting the pine boards into rings in preparation for lathe turning. These will be used as raw material to lathe turn the various pieces parts for my version of a Cygnus Probe. I anticipate I may need to use plywood for some of these in order for them to be strong enough to not split during the turning. We'll see.

They look beefy... but most of this will end up as sawdust on the floor.

 

[lakeroadster]

Turning Parts On The Wood Lathe - Day 01

 

[lakeroadster]

Turning Parts On The Wood Lathe - Day 02

I decided to try using some cabinet grade plywood as the raw materials for the components. Using the 3/4" pine just wasn't durable enough and it tends to split along the grain line.

It worked out really well. It was also really easy to cut on the lathe.

 

[lakeroadster]

Turning Parts On The Wood Lathe - Day 03

 

[lakeroadster]

Turning Parts On The Wood Lathe - Day 04

Finished cutting the Barrel Upper Head and made the Lower Centering RIng.

Mock up shown below.... Time to start glueing parts together.

 

[lakeroadster]

Added Ye Ole Base Drag trick to the Open Rocket Sim

 

[dhbarr]

Added Ye Ole Base Drag trick to the Open Rocket Sim

View attachment 505826

Just a word of caution on your drag cone -- I would have expected it to be the diameter of your flat aft plate, not the largest portion above the transition.

 

[lakeroadster]

Just a word of caution on your drag cone -- I would have expected it to be the diameter of your flat aft plate, not the largest portion above the transition.

Thanks. I updated the simulation and the stability numbers are good in that configuration also.

This design has a plethora of diameters to choose from .

Better to be conservative, I wouldn't want the Cygnus Probe Ship to get sucked into a "Black Hole".

 

[lakeroadster]

Cones & Rings

 

[lakeroadster]

Assembly Day 01 - Motor Mount & Lower Centering Ring

 

[Daddyisabar]

Added Ye Ole Base Drag trick to the Open Rocket Sim

View attachment 505826

Base drag is one of just a few friends the oddrocketeer has.

 

[Daddyisabar]

I would use a shorter delay, more like a 4 with as much punch as you can get. Even at altitude you will need some time to deploy.

 

[MadRocketer]

Looking good!

 

[lakeroadster]

I would use a shorter delay, more like a 4 with as much punch as you can get. Even at altitude you will need some time to deploy.

Your absolutely right. I have F42-4T's. The 8T's are just from the package I have open. An 8 second delay would be a major pucker factor....

 

[Daddyisabar]

Your absolutely right. I have F42-4T's. The 8T's are just from the package I have open. An 8 second delay would be a major pucker factor....

View attachment 506107 View attachment 506110

Trust the machines! No need for mindsim or a Butlarian Jihad.

 

[lakeroadster]

Assembly Day 02 - Kevlar Conduit, Lower Head and Lower Cone

 

[lakeroadster]

Assembly Day 03 - Barrel Centering Ring / Barrel Upper Head & Upper Cone

Now it's finally starting to shape..

 

[lakeroadster]

The Probe Ship Gets A New Pair Of Shoes....

 

[lakeroadster]

Notching The Rings For The Launch Rod

 

[MadRocketer]

 

[lakeroadster]

Swing Test

This is the first rocket where I have used the The Rocksim/Openrocket Base Drag Trick in Open Rocket (see post #41). So for me with this specific rocket design the swing test will not only check stability of the rocket, but it also will pre-validate the Open Rocket results. Of course the real validation will be on launch day.

Swing Test #1: No Ballast = Unstable Flight

Per Open Rocket this should yield a stability caliber of 0.859 (negative 0.275 w/o base drag hack). Swing test showed this configuration to be unstable.​

Swing Test #2: 0.6 Ounces of Ballast = Marginally Stable Flight

Per Open Rocket this should yield a stability caliber of 0.954 (negative 0.18 w/o base drag hack). Swing test showed this configuration to be marginally stable.​

Swing Test #3: 2.1 Ounces of Ballast = Stable Flight

Per Open Rocket this should yield a stability caliber of 1.14 (0.01 w/o base drag hack). Swing test showed this configuration to be stable.​

​

So based on the swing test, the base drag hack in Open Rocket seems to be accurate & the Cygnus Probe Ship appears to be stable in this configuration.

I still however need to add the slinky to the upper mast, and the outriggers to the barrel section, at which point I'll do another swing test.

When I do a swing test:

Stable: No dancing on the end of the string when the rocket is being spun "at speed", meaning once I get it's velocity at a steady constant rate. Nose in the wind, no pitching.​

Marginally Stable: Some minor pitching. Lets say +/- 10 degrees​

Unstable: Severe pitching and / or tumbling​

 

[Pem Tech]

Looks kind of like View attachment 500403 but without the Queller Drive.

That was a great Space 1999 episode.

 

[Pem Tech]

Trust the machines! No need for mindsim or a Butlarian Jihad.

Hey! Stay out my CHOAM contracts or I'll send the Sisters after you.

 

[lakeroadster]

Outriggers

Made from 3/16" diameter Poplar Dowels

 

[modeltrains]

Drawings and a Rendering (Revised 01-25-2022)

Somebody can maybe help me out here, my health is a mess and I'm tired and hurting having just arrived home from the laundromat and I can't for the life of me figure out whether those drawings and renderings are engineering or art, my brain just simply is not going to do that.

 

[lakeroadster]

Outrigger Diagonal Braces

The outriggers were not nearly as durable as they needed to be. I looked at some of the movie stills from The Black Hole movie. The ship had diagonal braces, it looks like cables. So I decided to add some 1/8" dia. braces.

The outriggers are hell-for-stout now. Maybe even up to a 19 ft/sec ground hit?

 

[lakeroadster]

@Daddyisabar ... those outriggers would be great for hanging some rear streamers..... where did I get that idea?