3 Stage MAMMOTH

[RocketNut9]

My latest bird is a 3 stage Mammoth. The first stage is a cluster of 3 F-15. Also the first stage is 3D printed ( Creality 3D® CR-10 large format printer, Appx 65Hours to print entire booster), that channels the boosters burn out gases to a single point. If you want to see the tech info athttps://grabcad.com/library/3-motor-cluster-booster-1. Yes I am going to need FFA waver to fly with all 3 stages.

Yes I have reinforce the main body tube, to with stand the high Gs loads.

 

[BDB]

I love it! 2017 is going to be the year of awesome multi-stage flights.

 

[dhbarr]

That's absurd; I love it!

Why the NC swap?

 

[ksaves2]

Impressive. Is the material going to melt from the gases though on that first stage? Kurt

 

[Cabernut]

I hope in addition to the waiver you have a really big field and a pair of binoculars.

Funny how long 3D printing actually takes. I recently printed a BT-70 nose block on low-res 0.3mm and it still took nearly 3 hours.

Good luck!

 

[RocketNut9]

That's absurd; I love it!

Why the NC swap?

NC swap?

ksaves2:

The gasses will soften the PLA but the time the tubes are exposed to these gases is very very short time. To help the tubes survive the walls are almost 3mm thick. Also as the number of flights encresses more and more exhaust partilcals will get embeded into the tubes inside walls. Making the tube able to with stand the gases.

Cabernut

I am using a PLA filament which has to be print at a lower for proper adhesion. Also the model size 268mm/233mm/216. Then add the complex inter structures. all this takes time to print.

 

[dhbarr]

Mammoth stock has a black conical NC w/ an extended cylindrical

 

[RocketNut9]

Mammoth stock has a black conical NC w/ an extended cylindrical

Grandson hide it so I to replace it.:y: I ask Estes for a replacement, was told there was no replacement. So I ordered there 2" nose cone,which according to Estes is the same size,just the lengthen is shorter. If some knows where I can get a replacement, please speak up.

 

[swatkat]

I think I can print this in one piece as well... will try it tomorrow. My printer is a little faster though. I'm thinking 5-6 hours tops at standard resolution. (Lulzbot Taz 6)

 

[samb]

That is a nice bit of fabrication. I thought the new nose cone might be a lead slug to get it balanced for flight. :wink: I might be more concerned about the combined heat of 3 29mm boosters letting go at the same time. But I don't have any real number on actual temperatures generated. Hot though. Any concern about the pressure wave separating the booster before the 2nd stage motor ignites ? I know Stine and Van Milligan have written about venting boosters around the interstage coupler to prevent this. Might be worth a Google or two. Same nose cone shape is used on the Majestic. Good luck with it.

 

[RocketNut9]

I think I can print this in one piece as well... will try it tomorrow. My printer is a little faster though. I'm thinking 5-6 hours tops at standard resolution. (Lulzbot Taz 6)

Looking at spec of the Lulzbot Taz 6 it should fit, abit tight tho. I think your printer will take a longer print time then just a few hours. Using nylon filament at 35 mm/s it takes my printer almost 3 days to print. PLA at 60 mm/s it still took almost 1.5 days. The reason is all the internal support structure, not to mention the fins are very large. Then there is the flame tubes which have complex shape and 3mm thick. All this adds up to long print time and 228grams of nylon filament. Can you post the print time it took your printer to print the booster.

That is a nice bit of fabrication. I thought the new nose cone might be a lead slug to get it balanced for flight. :wink: I might be more concerned about the combined heat of 3 29mm boosters letting go at the same time. But I don't have any real number on actual temperatures generated. Hot though. Any concern about the pressure wave separating the booster before the 2nd stage motor ignites ? I know Stine and Van Milligan have written about venting boosters around the interstage coupler to prevent this. Might be worth a Google or two. Same nose cone shape is used on the Majestic. Good luck with it.

The flame tubes are 3mm thick. The time the tubes are exposed to the hot gasses is very short ( < .5 sec), even if all three lets loose at the same time. Also some of the exhaust partials will get embedded on ever flight, meaning with each flight the tubes will get a coating which helps to protect the tubes. As for the pressure wave the is three pressure relief ducts, allowing any excess pressure to vented over board. This along with the stage coupler been very tight fitting should hold the 2 stages together until the upper stage ignited.

 

[dhkaiser]

love to see a .ork file on this setup. BTW I have a spare Mammoth NC, it is a very snug fit and I have not used it. You are welcome to it.

 

[RocketNut9]

I have not heard a file ".ORK" extension:sad:. My cad (Geomagic Design) package does not have a export function with that extension. May be there is program that can convert a cad file to a ORK file.

 

[Kallahan11]

.ork is an Open Rocket file, which will allow you to sim the flight using open rocket. I don't think you'll need to reinforce the tube BTW. I've launched Pro Series 2 rockets with an H195 which has way more acceleration that 3 F-15's on an unreinforced tube.

 

[BDB]

That is a nice bit of fabrication. I thought the new nose cone might be a lead slug to get it balanced for flight. :wink: I might be more concerned about the combined heat of 3 29mm boosters letting go at the same time. But I don't have any real number on actual temperatures generated. Hot though. Any concern about the pressure wave separating the booster before the 2nd stage motor ignites ? I know Stine and Van Milligan have written about venting boosters around the interstage coupler to prevent this. Might be worth a Google or two. Same nose cone shape is used on the Majestic. Good luck with it.

The pressure build-up problem is real. I described it towards the end of my thread about staging a 29 mm motor to a 24 mm motor. The booster kept separating before it lit the sustainer: https://www.rocketryforum.com/showthread.php?128250-Magnum-II

I'm working on a 3x24mm cluster booster staging to a 1x24mm sustainer right now. I'm planning to vent the booster to prevent the problem from happening again.

 

[rstaff3]

That booster is really cool, great idea. You should have some venting as the staging is indirect.

 

[RocketNut9]

The pressure build-up problem is real. I described it towards the end of my thread about staging a 29 mm motor to a 24 mm motor. The booster kept separating before it lit the sustainer: https://www.rocketryforum.com/showthread.php?128250-Magnum-II

I'm working on a 3x24mm cluster booster staging to a 1x24mm sustainer right now. I'm planning to vent the booster to prevent the problem from happening again.

If you want I can help you in design possibly 3D print it for you. I would have to change my booster from 29mm to 24mm engines.

That booster is really cool, great idea. You should have some venting as the staging is indirect.

My booster does have staging pressure relief ducts as shown in this screen shot. I design the ports to provide up wards thrust pushing the booster tightly to next stage. then when the stage ignites the pressure of that will push off the stage.

 

[rstaff3]

My booster does have staging pressure relief ducts as shown in this screen shot. I design the ports to provide up wards thrust pushing the booster tightly to next stage. then when the stage ignites the pressure of that will push off the stage.
View attachment 312352

I'm not sure how long thin vents will perform vs simple holes near the bottom of the 2nd booster. Any thoughts on when this might fly?

 

[RocketNut9]

Here is screen shots of the flame tube detail. As you can see the flame tube guides the hot gases to a single point that's very close to upper stage engine nozzle. If my thinking is correct. When the boosters engine(s) breaks lose the gases are shot a the upper stage engine. Producing a flame that about 5 to 10 inches long. Meaning even if the booster seprates the flame will still ignite the upper stage. Yes all this will happen in a fraction of a second.
.

 

[samb]

The pressure build-up problem is real. I described it towards the end of my thread about staging a 29 mm motor to a 24 mm motor. The booster kept separating before it lit the sustainer: https://www.rocketryforum.com/showthread.php?128250-Magnum-II

I'm working on a 3x24mm cluster booster staging to a 1x24mm sustainer right now. I'm planning to vent the booster to prevent the problem from happening again.

I'ma believer ! I think they're cheap insurance. Don't know if there is a concensus on size/number/location though. I once built a little BT-50/18mm motor booster that vented out the back through little notches in centering rings, kinda like the OP has done here. It worked well enough. On the other hand, John Boren did not use any in his Booster-55, Booster-60, and PS-II Booster units. His comments on the subject are buried in a thread somewhere around here. Hard for me to second-guess the Chief Designer.

 

[samb]

Here is screen shots of the flame tube detail. As you can see the flame tube guides the hot gases to a single point that's very close to upper stage engine nozzle. If my thinking is correct. When the boosters engine(s) breaks lose the gases are shot a the upper stage engine. Producing a flame that about 5 to 10 inches long. Meaning even if the booster seprates the flame will still ignite the upper stage. Yes all this will happen in a fraction of a second.
View attachment 312353 .View attachment 312354

I'll say it again, really slick fabrication. I think many of us are familiar with model rocket staging operations theory and practice. I'm sure most of us are looking forward to a flight report filled with great success. Is this the prototype ?

 

[Nytrunner]

This is a cool project with design work. To throw in 3-cents of thought, consider ground testing the staging. Strap down the 1st and 2nd stage with motors, and light em up. Safely of course. It would be a terrible thing to see an unforeseen problem inflight.

 

[samb]

... consider ground testing the staging. Strap down the 1st and 2nd stage with motors, and light em up. Safely of course. ....

I'm having a hard time wrapping my head around this one. Have you done this ? Seen it done ? Successfully ??? All I'm envisioning is chaos and destruction.

 

[Nytrunner]

I'm having a hard time wrapping my head around this one. Have you done this ? Seen it done ? Successfully ??? All I'm envisioning is chaos and destruction.

Simplest thing that comes to mind is stick the 2nd stage front down in a hole, attach the 1st stage as he would for flight, and then light. There has to be a dozen other ways that involve jigs and tie-downs in some fashion. It all depends on how much he wants to risk a fair sized rocket coming down ballistic if stage 2 fails to ignite being untested until flight.

 

[BDB]

I already downloaded the .stl file for your cluster booster. I think I'm going to have to try this on my daughter's mammoth too. She'll love it.

Here's my 3x24mm canted cluster booster that I'm working on. Built the old fashioned way. Just needs a vent hole and some paint and it should be ready to fly next month.

 

[RocketNut9]

I'll say it again, really slick fabrication. I think many of us are familiar with model rocket staging operations theory and practice. I'm sure most of us are looking forward to a flight report filled with great success. Is this the prototype ?

Yes it's a flyable prototype. I have ordered the motors for a static test.

I'm having a hard time wrapping my head around this one. Have you done this ? Seen it done ? Successfully ??? All I'm envisioning is chaos and destruction.

This my design from the ground up. Like I said I am going to do a static test. Where I secure the second stage. So when the first stage burn trough it will drop off. This will tell me if the flame tubes design is correct.


OpenRocket sounds like a very powerful package. If can find the time I will try to model this booster. Being a newbe to OpenRocket I might need a lot help:y:

 

[dcullen]

Which nylon filament are you using?

 

[RocketNut9]

First I started with Taulman Nylon Bridge 3D Printing Filament ( https://www.ebay.com/itm/Taulman-Ny...mm-/331861959844?_trksid=p2141725.m3641.l6368). After several tries I gave up. The outer shell was just to soft and flexible.Along with printing problems. I am now using PLA now with a high performance coating (XTC-3D 3D Print Coating (https://www.ebay.com/itm/XTC-3D-Hig...739426?hash=item25c197c6a2:g:nKAAAOSwZVlXp26P )). I am told it makes a very hard shell along with smoothing out the shell. With two coats it likes like it was injection modeled. I have order some and will keep you informed.

===========
FYI
The coupler keeps breaking off because it is to thin. So I redid the booster without the coupler. Instead I added a slot so a couple can be glued in. This is proving a lot better and stronger interface.

 

[samb]

I'll say it again, really slick fabrication. I think many of us are familiar with model rocket staging operations theory and practice. I'm sure most of us are looking forward to a flight report filled with great success. Is this the prototype ?

Yes it's a flyable prototype. I have ordered the motors for a static test.

I asked the question about prototype because I was wondering if you had built and flown a smaller version using 13 or 18mm motors.

I'm having a hard time wrapping my head around this one. Have you done this ? Seen it done ? Successfully ??? All I'm envisioning is chaos and destruction.

This my design from the ground up. Like I said I am going to do a static test. Where I secure the second stage. So when the first stage burn trough it will drop off. This will tell me if the flame tubes design is correct.

Not sure why you quoted my reply to Nytrunner's post suggesting a static test. I'm not suggesting anybody light a model rocket motor except when properly installed in a model rocket pointed at the sky under all applicable safety code criteria.

OpenRocket sounds like a very powerful package. If can find the time I will try to model this booster. Being a newbe to OpenRocket I might need a lot help:y:

Me too.

 

[cwbullet]

I would love to build one but I tried to have on printed by severla vendors online but it was too rich for my blood.