Mars Lander - Scratch Built - 3" Nominal Diameter

[lakeroadster]

Here's a Mars Lander that's a scratch build.

The body diameter is a little over 3", and it's one piece turned from wood.

Power is via a 29mm motor in a rear eject spool. At ejection the spool and the motor are recovered via a parachute. A separate drogue chute is deployed for the lander, the drogue orients the lander so it lands on it's feet. It uses 3 legs instead of the original 4 that the OOP kits used. The rocket is actually more stable with 3 legs.

Thanks to user @wonderboy for his .ork file. I used that as a point of departure to make this one.

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[Jeremy Sim]

Fantastic!!

 

[BABAR]

Sooooo……?


The ejection charge deploys the chute from the body.

The motor and parachute segment are very loose in the rocket, solid going up/forward, but falls out by gravity when the chute deploys from body.

If this is the plan, I love it! I haven’t seen this trick used before, although that may not be saying much. Original or not, it’s a brilliant idea.

Gotta be careful carrying it out to the pad and setting it on the rod! This might benefit from a “remove before flight” pin with a big red or orange ribbon to hold the two pieces together between launch table and pad.

 

[lakeroadster]

Sooooo……?


The ejection charge deploys the chute from the body.

The motor and parachute segment are very loose in the rocket, solid going up/forward, but falls out by gravity when the chute deploys from body.

If this is the plan, I love it! I haven’t seen this trick used before, although that may not be saying much. Original or not, it’s a brilliant idea.

Gotta be careful carrying it out to the pad and setting it on the rod! This might benefit from a “remove before flight” pin with a big red or orange ribbon to hold the two pieces together between launch table and pad.

A piece of blue painters tape works pretty well.

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[BABAR]

As long as you remember to pull it off. Don’t ask how I know this

 

[lakeroadster]

As long as you remember to pull it off. Don’t ask how I know this

I leave it in place. Blue painters tape is no match for an Estes D12 ejection charge.

Actually, just using a clothespin clipped to the launch rod, such that the spool contacts the clothespin is all that is needed. The motor thrust keeps the spool in place, and during the coast phase the rocket is decelerating, which also keeps the spool in place.

 

[BABAR]

I leave it in place. Blue painters tape is no match for an Estes D12 ejection charge.

Actually, just using a clothespin clipped to the launch rod, such that the spool contacts the clothespin is all that is needed. The motor thrust keeps the spool in place, and during the coast phase the rocket is decelerating, which also keeps the spool in place.

i see a key difference between your Mars Lander and the Columbine.

Columbine the ejection charge has one job, kick the motor/spool Out the back. Period. End.

Mars lander ejection charge has to eject the nose of the booster to eject the drogue (which I guess is the one and only chute for the body of the rocket, which should be pretty light since all it has is nose, body, and fins, no motor or motor spool.

but you also have to get the motor spool out of the rocket body. I get antsy when I try to use one ejection charge to do 2 Jobs, it proooooooobaaaaably will work, but it’s easy to gum things up . If you try to do both, you have a potential for a Big Daddy failure, where you have a partial venting of the ejection charge BEFORE the spool is completely out. Not my rocket, but you are assuming the ejection charge had the oomph to BOTH deploy the drogue AND eject the spool.

that is why in my opinion the most reliable is to let the spool fall out by GRAVITY.

ejection fires, pushes out the nose cone and chute for the BODY. In fact, I think that’s ALL it should do. Just about guaranteed that step will succeed.

motor spool is still in the body. That’s okay, the chute will open, the rocket will orient nose up. Probably with a jerk, which should by inertia dump the spool.

now, assuming the spool is reeeeeaaaalllly loose, once the body is nose up under chute the spool will slide right out the back by inertia Or gravity. No tape, no friction fit. This is how I set up my two stage rockets, there is enough ”nesting” to keep the alignment perfect, but the sections will separate with just gravity (or nearly so). Kind of the same for my nose cones on regular rockets, which is why if I DO have to rig them before transport I use a long piece of pink masking tape, most of it folded back, to hold the cones on with the rest as a ”flag” so obvious nobody can miss it.

with the exception of using ejection charge to burn my “burn bands” AND light a booster o blow off a cone (and even that is a bit dicey) I try to avoid relying on an Ejection charge to do two separate things. It’s kind Of reverse redundancy.

 

[lakeroadster]

i see a key difference between your Mars Lander and the Columbine.

Columbine the ejection charge has one job, kick the motor/spool Out the back. Period. End.

Mars lander ejection charge has to eject the nose of the booster to eject the drogue (which I guess is the one and only chute for the body of the rocket, which should be pretty light since all it has is nose, body, and fins, no motor or motor spool.

but you also have to get the motor spool out of the rocket body. I get antsy when I try to use one ejection charge to do 2 Jobs, it proooooooobaaaaably will work, but it’s easy to gum things up . If you try to do both, you have a potential for a Big Daddy failure, where you have a partial venting of the ejection charge BEFORE the spool is completely out. Not my rocket, but you are assuming the ejection charge had the oomph to BOTH deploy the drogue AND eject the spool.

that is why in my opinion the most reliable is to let the spool fall out by GRAVITY.

ejection fires, pushes out the nose cone and chute for the BODY. In fact, I think that’s ALL it should do. Just about guaranteed that step will succeed.

motor spool is still in the body. That’s okay, the chute will open, the rocket will orient nose up. Probably with a jerk, which should by inertia dump the spool.

now, assuming the spool is reeeeeaaaalllly loose, once the body is nose up under chute the spool will slide right out the back by inertia Or gravity. No tape, no friction fit. This is how I set up my two stage rockets, there is enough ”nesting” to keep the alignment perfect, but the sections will separate with just gravity (or nearly so). Kind of the same for my nose cones on regular rockets, which is why if I DO have to rig them before transport I use a long piece of pink masking tape, most of it folded back, to hold the cones on with the rest as a ”flag” so obvious nobody can miss it.

with the exception of using ejection charge to burn my “burn bands” AND light a booster o blow off a cone (and even that is a bit dicey) I try to avoid relying on an Ejection charge to do two separate things. It’s kind Of reverse redundancy.

The drogue chute ejects out that back... with the spool. It's Kevlar shock cord is attached on the outside of the rocket, leading up to the top of the rocket.

The rocket is stable and lawn darts if it doesn't have something to reorient it... Here's a photo of a bad day for one of Aeromoe's Mars Landers

 

[BABAR]

Will there be a line connecting the motor under chute to the body under separate chute? Or will
the body and motor recover separately?

 

[lakeroadster]

Will there be a line connecting the motor under chute to the body under separate chute? It will the body and motor recover separately?

I'm thinking something like this arrangement:

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