L2 low altitude rocket

Lt72884

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Im looking for a good L2 kit that has a lower altitude, so something short and stubby, maybe the bruiser? or something similar. This will be for my certification of lvl 2 in a few weeks.

2000 feet seems like a decent altitude, but im willing to even go for a 1500 foot apogee haha.

I dont need a high altitude for my lvl 2 cert, just want to have a nice chill launch haha

thanks for all the help so far.
oh, a side question, im looking for the recommendation of aspect raitio for rocket length compared to diameter. I have been reading Steins book and have not seen this particular thing yet. I have seen the recommendations for fins.
 

kenstarr

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LOC Warlock or Wildman Gizmo xl.
I've got the Warlock ready to fly on a K850 DM. Simmed altitude from todays office work is, well, Id have to pull it up again but it's in the neighborhood of 2000' or less. Gizmo xl is under construction. Beast of a rocket. Should be able to use it as blocking to prop up a truck for repair work.
Ken
 

BDB

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We have a 3000 ft ceiling at our local field. One of our members did an L2 cert flight with a LOC 5.5” Nike Zeus. It flew on a K motor to about 2k ft. Awesome rocket; awesome flight.

5CA51B7B-6B5A-4552-899A-3A887DDC4D58.jpeg
 

Steve Shannon

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Im looking for a good L2 kit that has a lower altitude, so something short and stubby, maybe the bruiser? or something similar. This will be for my certification of lvl 2 in a few weeks.

2000 feet seems like a decent altitude, but im willing to even go for a 1500 foot apogee haha.

I dont need a high altitude for my lvl 2 cert, just want to have a nice chill launch haha

thanks for all the help so far.
oh, a side question, im looking for the recommendation of aspect raitio for rocket length compared to diameter. I have been reading Steins book and have not seen this particular thing yet. I have seen the recommendations for fins.
A fairly typical aspect ratio for rockets is about 10:1. Obviously there are a lot of rockets that don’t comply, but it’s pretty easy to design a 10:1 aspect ratio rocket that’s stable.
 

Lt72884

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A fairly typical aspect ratio for rockets is about 10:1. Obviously there are a lot of rockets that don’t comply, but it’s pretty easy to design a 10:1 aspect ratio rocket that’s stable.
Do you know where this aspect ratio is/was documented? IE, in a book, from a website etc? Need to source it in a report for class

thanks
 

Lt72884

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We have a 3000 ft ceiling at our local field. One of our members did an L2 cert flight with a LOC 5.5” Nike Zeus. It flew on a K motor to about 2k ft. Awesome rocket; awesome flight.

View attachment 540097
Awesome Rocket. I likew this one too. Dang, now i gotta figure this out by november. My lvl 1 is a LOC IV and im not sure if that can do a lvl 2 flight. It might not be strong enough
 

Lt72884

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LOC Warlock or Wildman Gizmo xl.
I've got the Warlock ready to fly on a K850 DM. Simmed altitude from todays office work is, well, Id have to pull it up again but it's in the neighborhood of 2000' or less. Gizmo xl is under construction. Beast of a rocket. Should be able to use it as blocking to prop up a truck for repair work.
Ken
wow, that gizmo xl is FAT!
 

Lt72884

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You’re going to have to do your own school research, but I’ll give you a hint. Instead of calling it aspect ratio, call it “fineness”.
haha, ok, so its more of a thing that happened rather than a design constraint or standard. I have found many websites showing a 10:1 or even a 20:1 aspect ratio, but its never quoted of where that came from haha

EDIT:
OHHH, read that wrong, i thought you put FINESSE... damn dyslexia. I read it as its a custome type thing and to "just finesse it" like wing it. but now i see what you mean via this article

 
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Zeta

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Im looking for a good L2 kit that has a lower altitude, so something short and stubby, maybe the bruiser? or something similar. This will be for my certification of lvl 2 in a few weeks.

2000 feet seems like a decent altitude, but im willing to even go for a 1500 foot apogee haha.

I dont need a high altitude for my lvl 2 cert, just want to have a nice chill launch haha

thanks for all the help so far.
oh, a side question, im looking for the recommendation of aspect raitio for rocket length compared to diameter. I have been reading Steins book and have not seen this particular thing yet. I have seen the recommendations for fins.
consider the LOC Wolverine. Lots of room to work inside and easy to add weight to.
 

Lt72884

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consider the LOC Wolverine. Lots of room to work inside and easy to add weight to.
hmm, i might get this one. Wolverines are our school mascot so i could paint this the school colors haha
 

Madison Alum

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Did my Level 2 with the LOC Doorknob. Has flown great on everything but Redlines. Both times I flew it on Redlines, the delay was way off and it zippered the crap out of it. Repairing it with a stiffy coupler inside of a regular coupler. Will be somewhat heavier when repairs are complete. Somewhere on the forum, there is a thread about an av bay set up for the nosecone, for use after your initial cert. Can't remember who posted it though. I imagine it would work on any of the 7.5 in LOC nosecones. Chris Attebery had the av bay.
 
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CoyoteNumber2

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Any rocket can be a low-altitude rocket, just add more weight. Then take the weight out if you want to fly higher.
 

Lt72884

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Any rocket can be a low-altitude rocket, just add more weight. Then take the weight out if you want to fly higher.
True, If i wanted to use my LOC IV lvl 1 rocket for my lvl 2 cert, can i add sand or something like that to the payload area? i dont want to add it to the cone since that might mess with the CP and i dont have a sim file for the loc precession LOC IV rocket yet to test
 

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Adding weight to the nose cone is not going to "mess with the CP". The CP is based on the characteristics of the airframe and how pressure is applied to the surface area, not on the weight of the components and that weight distribution.

Generally a larger motor as would be used for a L2 flight will weigh more than a smaller motor used for L1, and could result in the CG being moved aft closer to the CP, with a resulting adverse impact on stability.

For that reason, most tend to add weight to the nosecone, since the moment arm is longer and less overall weight is required to achieve a desired shift in CG. If you are only seeking to 'ballast up' to restrict altitude, you could add mass elsewhere in the airframe, but you really need to sim the model with that change to see what the impact on CG is when factored in with your L2 motor. Load several L2 motors in your configuration as well to see what the impact to apogee altitude is as well.
 

waltr

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True, If i wanted to use my LOC IV lvl 1 rocket for my lvl 2 cert, can i add sand or something like that to the payload area? i dont want to add it to the cone since that might mess with the CP and i dont have a sim file for the loc precession LOC IV rocket yet to test
That is a scary statement from someone going for an L2 cert.
This is basic rocket stability, motor thrust verse Weight, air speed & drag. All should be understood before doing L2 (these are on the written test).
 

JSW

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Im looking for a good L2 kit that has a lower altitude, so something short and stubby, maybe the bruiser? or something similar. This will be for my certification of lvl 2 in a few weeks.

2000 feet seems like a decent altitude, but im willing to even go for a 1500 foot apogee haha.

I dont need a high altitude for my lvl 2 cert, just want to have a nice chill launch haha

That's a great idea! I got an Apogee Katana for my L2 attempt,... but really don't want to mess with Dual Deploy. It goes 3k-4k feet with smallest L2 motor. Was planning on Single Deploy using a a JLCR.

I would say the LOC Warlock would be a nice one 7.5 diameter tube

That looks like an ideal kit for lower L2 attempt. 2.25k feet.

Do you think just a JLCR would be ok? Or maybe a drone chute, and then JLCR for main?

Thanks!
 

Zeta

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True, If i wanted to use my LOC IV lvl 1 rocket for my lvl 2 cert, can i add sand or something like that to the payload area? i dont want to add it to the cone since that might mess with the CP and i dont have a sim file for the loc precession LOC IV rocket yet to test
I think that the 5.5 inch and 7.6 inch air frames bring the advantage of more drag, so you don't need as much weight in a rocket. I was looking at the Big Nuke 5.5" rocket kit last knight and it was simulating about 2200' AGL. with an Aerotech J 250 -9... total impulse 709. The rocket itself weights between 7 and 9 pounds depending on build. Considering that my sims tend to overestimate the apogee, the flight would probably be under 2k. If you want to fly lower go up to the 7.6 inch airframe...at 11 pounds apogee is under 1000.
 
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BDB

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Contrary to popular opinion, additional weight often INCREASES altitude because the rocket will have more momentum causing it to coast longer after motor burnout. Check out post #5 in this thread, where I struggled to wrap my mind around this as I was building my L2 rocket.

To minimize altitude, you want to increase drag--not increase mass. The best way to do that is to increase the rocket's diameter. (Or cover your fins with shag carpet.)
 

techrat

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I've built a few rockets with payload bays. When I want it to not fly out of sight, I just add a payload. Old engine casings.
 

ThirstyBarbarian

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Contrary to popular opinion, additional weight often INCREASES altitude because the rocket will have more momentum causing it to coast longer after motor burnout. Check out post #5 in this thread, where I struggled to wrap my mind around this as I was building my L2 rocket.

To minimize altitude, you want to increase drag--not increase mass. The best way to do that is to increase the rocket's diameter. (Or cover your fins with shag carpet.)

That is correct. Drag is the way to keep altitude low, not weight. Sometimes adding weight increases altitude.
 

Lt72884

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Adding weight to the nose cone is not going to "mess with the CP". The CP is based on the characteristics of the airframe and how pressure is applied to the surface area, not on the weight of the components and that weight distribution.

Generally a larger motor as would be used for a L2 flight will weigh more than a smaller motor used for L1, and could result in the CG being moved aft closer to the CP, with a resulting adverse impact on stability.

For that reason, most tend to add weight to the nosecone, since the moment arm is longer and less overall weight is required to achieve a desired shift in CG. If you are only seeking to 'ballast up' to restrict altitude, you could add mass elsewhere in the airframe, but you really need to sim the model with that change to see what the impact on CG is when factored in with your L2 motor. Load several L2 motors in your configuration as well to see what the impact to apogee altitude is as well.
WOW.. i totally meant CG not CP. CP is based on the area and i have used the barrowmen equations to find it recently. I meant adding mass to the cone could move the cg closer or even behind my cp.
thanks for correcting my error before i could see it.
 

Adam3836

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That's a great idea! I got an Apogee Katana for my L2 attempt,... but really don't want to mess with Dual Deploy. It goes 3k-4k feet with smallest L2 motor. Was planning on Single Deploy using a a JLCR.



That looks like an ideal kit for lower L2 attempt. 2.25k feet.

Do you think just a JLCR would be ok? Or maybe a drone chute, and then JLCR for main?

Thanks!
I would think the JLCR would work fine..
run some sims see what kind of altitude your looking at.
I know people have lofted the warlock up on i- motors and had regular parachute deployment at apogee but that’s cause it was lower altitudes like 1500 or less
It’s definitely a hefty rocket I just finished mine and put primer on recently
 

David_Stack

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I meant adding mass to the cone could move the cg closer or even behind my cp.
No, I don't think you meant that either... (and if you did, I'd love to see the sim file/design).

Since CG should be forward of CP, adding mass to the cone (I assume we are talking nose cone, not tail cone) will move the further forward of the CP.

I think you (and your professor if this is all driven by their agenda) need to slow down...
 

Lt72884

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That is correct. Drag is the way to keep altitude low, not weight. Sometimes adding weight increases altitude.
good point. coasting velocity will be affected if i add to much weight. i forgot about that part of physics. In-fact, i now am using the impulse equation based on a change in momentum to calculate some things.
 

Lt72884

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Yes. This is the path to follow.

Take what you've learned and use The Force* to moderate the altitude.



*FD, because "Be the ball, Danny" doesn't work in this case.
ok, i can increase drag on my rocket and maybe add enough mass to not cause coasting distance to be affected.
maybe i can add something to my LOC IV fins to cause some drag haha or to the BT
 
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