Thinking About Building a Low-Powered Multi-Stage N-1 - Possible or Crazy?

[BigMacDaddy]

Has anyone seen a smallish multi-stage N-1 rocket? I saw a video of a huge 1/16th scale one w/ 3 stages at LRDS 20 and have seen a few other paper and 3D models that all seem to be 1 stage. Is this possible to do as 2 or 3 stages?

The N-1 thread by @kuririn motivated me to go back to a 3D design I had started on a while back. I am redrawing / redesigning based on other STL files I can find, other models, and prototype pictures. I am shooting for good enough in my design to keep this pretty easy to print and light enough weight to launch w/ 3x D-engines in base (although people keep sending me better and better images or plans so I can improve detail). Design is currently around 30" long and on the order of magnitude of 240g of ABS filament for most parts (no tubes, centering rings, motor mounts, chute/shock chord). Counting on recessing motors where and if I can to help stabilize this.



I modeled this as best I could in OpenRocket. Component weights are not accurate since I will be 3D printing this but just wanted to see what default transitions showed for CP location, etc... This rough plan has 6oz of weight in nose to get this stable across all stages.



This is obviously an oddroc from OR's standpoint and not sure I can you model draggy fins like these by just making really thick / short fins like I did here. Interestingly modeling fins as normal 3cmx3cm .2mm thick fins only moves the CP back a little over 1cm.


Comparing CP calculation from OR to the ones published on Apogee's site for a couple of existing models suggests that this CP calculation is not impossible (at least for the full model):

• Altaria: 88cm long / CP 44.75cm (50.85%)
• Really Koo Stuff: 41.5" long / CP 30" (72.3%)
• My OR Sim: 68.2 cm long / CP 48.1 cm (70.5%)

So what do you guys think? Worth doing or should I look for something simpler / lighter?

 

[BigMacDaddy]

Received some really great plans that show many of the details on the rocket (from a Russian book on the N-1). Now I need to decided if I should super-detail this or just do enough that it does not look like a blank transition section...

 

[BigMacDaddy]

This is where I am at detail-wise on the lower section...

 

[Daddyisabar]

I say...crazy.

 

[BigMacDaddy]

I say...crazy.

Haha... probably... I might not do a 3-stage but maybe a 2-stage?

Anyway, those later stages do not have the benefit of the drag fins at the bottom or the big conical transition / flange (however, they would be moving already).

Also 3D printing this will make it heavy and that weight will be distributed towards the much larger aft end. Lots of issues to deal with.

I was thinking of recessing motors a bit on each stage and was adding holes in the main stage to help create a bit of a GDS effect.

What if I use drag streamers or something in stage 2 and 3?

 

[Daddyisabar]

Pop out fins on upper stages. Booster stages will be heavy so some sort of recovery gear. Electronic ignition on second/ third stage. Variable CP and CG on the stages could be challenging. I know the Top Men have done Saturn Vs, don't know of an N1.

 

[jqavins]

"Possible or Crazy?" -- Both

Forget drag stabilization. Most of the time, in most rockets, and for most purposes, just forget about it. It's minor and unimportant unless you're talking about something as short and wide as a Fat Boy. Just get over it.

The expanding diameter toward the aft end creates the downward CP shift that you need. OR models that, and it (along with nose weight) is all you need.

You also therefore don't need the little square fins in the model.

As for the weight and CG, you should be able to override OR's computed weights for the various 3D printed pieces. Since you've written that the prints will take about 240 g of filament, you obviously have weight estimates for the pieces, and you can enter those into the OR model directly. Give me a little while and I'll work out the CG locations for the major pieces. (Lunch hour is over.)

 

[BigMacDaddy]

"Possible or Crazy?" -- Both

Forget drag stabilization. Most of the time, in most rockets, and for most purposes, just forget about it. It's minor and unimportant unless you're talking about something as short and wide as a Fat Boy. Just get over it.

The expanding diameter toward the aft end creates the downward CP shift that you need. OR models that, and it (along with nose weight) is all you need.

You also therefore don't need the little square fins in the model.

As for the weight and CG, you should be able to override OR's computed weights for the various 3D printed pieces. Since you've written that the prints will take about 240 g of filament, you obviously have weight estimates for the pieces, and you can enter those into the OR model directly. Give me a little while and I'll work out the CG locations for the major pieces. (Lunch hour is over.)

Thanks Joe -- I appreciate the offer. It takes a while to add detail to these items and it substantially affects weight. I also need some better software (or need to understand how to use better software) to help me hollow out the shapes I am making so that they print with just .8mm to 1.2mm outer layers.

I will slowly come back to this and update designs etc... so that I can get accurate weights. I would like to make one even if it winds up being a static model so will probably print parts someday and mocking it up to see how a two stage with ejected 3rd stage would fly...

Pretty busy at school these days grading papers but will share progress as I make it.

 

[modeltrains]

Possible or Crazy?

It is all open questions until the moment of thrust production.

 

[aerostadt]

I've wondered if the Really Koo Stuff N-1 could be converted to a cluster in the first stage.

 

[BigMacDaddy]

I've wondered if the Really Koo Stuff N-1 could be converted to a cluster in the first stage.

I am sure it could -- it is just 3D printed like this version would be...

 

[DarthMuffin]

The details look great so far! Bonus points if you use 30 engines like the original

 

[OverTheTop]

"Possible or Crazy?" -- Both

That's what eventually led to the full-scale V2 project.

 

[Rob Campbell]

I say both crazy and possible. Don't try to swallow the whole elephant. Start simple with a single stage "boiler plate" model ad a proof of concept. Then move to a multi-stage boiler plate model and then move to one with the details you want to add.

 

[neil_w]

That's what eventually led to the full-scale V2 project.

I would actually love to hear an account of the inception of that project (off-topic for this thread, but since you brought it up...)

 

[OverTheTop]

Karl had had a bit too much to drink one day and mentioned that people had done long rockets but nothing big and bulky like a V2. Then he half jokingly said "Let's build one!". Everyone said he was crazy but the seed had been sown. Normal build techniques would not have worked at that scale. Eventually he determined a method and a 1/4 scale proof of concept was built and flown. At that point he got the team together and the rest is history.

 

[aerostadt]

Andy Woerner had a huge 1/16 scale N-1 at LDRS-20. It is hard to find it on the internet.

[video=youtube;Tr5DLtjKYoQ]