Designing a Rocket for a (considerably) High Altitude Flight

[SuperNova-Rocketry]

Hello Forum, Its my first time posting on here as I really needed help with a few aspects of my team's next rocket. Our previous rocket has just been finalized today and will be launched later this week. We are hoping that by the time we begin building our next rocket we will have accumulated some funds, either by sponsor or crowdfunding.

The goal of our next rocket is to hopefully fly above 10 km and footage during the process. The issue is that I am struggling to design the rocket itself to reach these requirements. We were hoping to use fiberglass for the body, and either a 3D Printed or Aluminium CNC machined Nose Cone. This is the base version of the rocket (It has no internal components as we wont design those until we have a solid groundwork which the parts can be based around.
As you can see, the rocket has a apogee of 4000 meters, but that isn't enough for the requirements of the rocket. We have been working on low-altitude rockets (Under 5km) for a while now and me and my team really want to push further to develop for the Space shot we would like to attempt in around 4-5 years time. The rocket is based around the K1440 Cessaroni motor and I wanted to see if anybody could tell us how we could be able to make the rocket go higher, I have already reduced drag as much as possible and made the rocket to a suitable weight which would help it keep momentum. Are there any other ideas?

 

[David_Stack]

Search the forums here to look at some of the rockets built in an attempt to set the K-impulse (54mm airframe) altitude record.

A few examples:

https://www.rocketryforum.com/threa...for-nsl-west-launch-2023.180082/#post-2437090

https://www.rocketryforum.com/threads/attempting-the-k-and-l-altitude-records.168459/

 

[sharkbait]

Hello Forum, Its my first time posting on here as I really needed help with a few aspects of my team's next rocket. Our previous rocket has just been finalized today and will be launched later this week. We are hoping that by the time we begin building our next rocket we will have accumulated some funds, either by sponsor or crowdfunding.

The goal of our next rocket is to hopefully fly above 10 km and footage during the process. The issue is that I am struggling to design the rocket itself to reach these requirements. We were hoping to use fiberglass for the body, and either a 3D Printed or Aluminium CNC machined Nose Cone. This is the base version of the rocket (It has no internal components as we wont design those until we have a solid groundwork which the parts can be based around.
View attachment 631389As you can see, the rocket has a apogee of 4000 meters, but that isn't enough for the requirements of the rocket. We have been working on low-altitude rockets (Under 5km) for a while now and me and my team really want to push further to develop for the Space shot we would like to attempt in around 4-5 years time. The rocket is based around the K1440 Cessaroni motor and I wanted to see if anybody could tell us how we could be able to make the rocket go higher, I have already reduced drag as much as possible and made the rocket to a suitable weight which would help it keep momentum. Are there any other ideas?

I would re-examine your fin design and would re-think your motor choice to a long burn like the K-300

 

[Hobie1dog]

To the forum. I agree about using a long burning motor.

 

[Wayco]

I had to convert some of your numbers to get an idea about what you want to do. What I came up with is a minimum diameter rocket 64mm in diameter? Closest I have is a 54mm MD rocket made from carbon fiber. I added the K1440 CTI motor and my rocket sims to just over 15,000 ft. or 4.57 km. That's with a .4 coefficient of drag.
Looking at your rocket, I'm thinking you need a bigger rocket, and probably a few more years of experience flying high power rockets. Even with the biggest LOKI motor, the M1378, you would still come up short by a few hundred feet. That motor is almost 4 ft. long. Your design would not be long enough to hold that motor, and would probably not survive.
I also have a 3 inch (76mm) MD carbon fiber rocket that recently went slightly over 30,000 ft., but it took me two years and eight flights to get it there.

It's not unusual for this forum to get teams that have lofty goals, and I hate to shut them down, so I usually just don't comment at all, but your goal is possible, just not with anything like what you have in your first post.
The gap between building a rocket that can go to 5 km and one that can go to 10 km is HUGE. Building it in a simulation program is easy, the hard part is building it in the real world, and all the learning that goes with flying it.

 

[SuperNova-Rocketry]

I would re-examine your fin design and would re-think your motor choice to a long burn like the K-300

Yeah, I think the k-300 is a good idea, but the issue is that my current engine supplier dosent have any long burn engines. I’ll try to call him up and ask about ordering an engine like that

 

[SuperNova-Rocketry]

I had to convert some of your numbers to get an idea about what you want to do. What I came up with is a minimum diameter rocket 64mm in diameter? Closest I have is a 54mm MD rocket made from carbon fiber. I added the K1440 CTI motor and my rocket sims to just over 15,000 ft. or 4.57 km. That's with a .4 coefficient of drag.
Looking at your rocket, I'm thinking you need a bigger rocket, and probably a few more years of experience flying high power rockets. Even with the biggest LOKI motor, the M1378, you would still come up short by a few hundred feet. That motor is almost 4 ft. long. Your design would not be long enough to hold that motor, and would probably not survive.
I also have a 3 inch (76mm) MD carbon fiber rocket that recently went slightly over 30,000 ft., but it took me two years and eight flights to get it there.

It's not unusual for this forum to get teams that have lofty goals, and I hate to shut them down, so I usually just don't comment at all, but your goal is possible, just not with anything like what you have in your first post.
The gap between building a rocket that can go to 5 km and one that can go to 10 km is HUGE. Building it in a simulation program is easy, the hard part is building it in the real world, and all the learning that goes with flying it.

Thanks for the advice, I’ll have a look into how I could improve my rocket design. As for building the rocket, I agree it is definitely the hardest part and we hope to get much better at it soon.
I’ll try to lower the goal for the flight and if i’m being honest 10km wasn’t a needed goal it was just a reference point that we wanted to make the rockets go much higher. I’ll hopefully have more news on designs soon

 

[cbrarick]

look at all the other altitude seekers. Their designs are not to far afield from each other, but they are significantly different then what you have.
Also, I would guess all the successful high altitude shots have come from people who worked up to it - in other words, had a program of rocketry that led them to higher altitudes. You just don't start there and expect to be successful. Plus, there is significant hubris in being a college team. I've seen multiple teams trying to do things well outside of their experience, and the result is always the same.
My best guess is that you are thinking of Spaceport America Cup 30k commercial division. Why not start with the 10k, figure it out with a 38 mm MD rocket before you try to tackle 30k? the complexity and difficulty are not scalable. However, it gives you a stepping stone.

JMHO your mileage may vary, and I didn't stay at a special hotel last night :>

 

[Neutronium95]

Hello Forum, Its my first time posting on here as I really needed help with a few aspects of my team's next rocket. Our previous rocket has just been finalized today and will be launched later this week. We are hoping that by the time we begin building our next rocket we will have accumulated some funds, either by sponsor or crowdfunding.

The goal of our next rocket is to hopefully fly above 10 km and footage during the process. The issue is that I am struggling to design the rocket itself to reach these requirements. We were hoping to use fiberglass for the body, and either a 3D Printed or Aluminium CNC machined Nose Cone. This is the base version of the rocket (It has no internal components as we wont design those until we have a solid groundwork which the parts can be based around.
View attachment 631389As you can see, the rocket has a apogee of 4000 meters, but that isn't enough for the requirements of the rocket. We have been working on low-altitude rockets (Under 5km) for a while now and me and my team really want to push further to develop for the Space shot we would like to attempt in around 4-5 years time. The rocket is based around the K1440 Cessaroni motor and I wanted to see if anybody could tell us how we could be able to make the rocket go higher, I have already reduced drag as much as possible and made the rocket to a suitable weight which would help it keep momentum. Are there any other ideas?

What motor options do you have access to?

Breaking 10 km with a 54mm motor will require an extremely optimized design, essentially putting a nosecone packed with electronics and recovery systems on top of a motor. A long burn motor like the K300 would be a good choice, but I'd suggest looking into getting a L motor. The K300 in particular has also had some reliability issues in recent years.

10 km with a 75mm motor and rocket is more feasible. It will still require a more optimized airframe than your current design, and most likely would need at least a medium sized M motor, though a higher impulse motor will make things easier.

Take a look at the Tripoli records for K, L and M motors to see what people have done in the past as a point of comparison.

 

[SuperNova-Rocketry]

What motor options do you have access to?

Breaking 10 km with a 54mm motor will require an extremely optimized design, essentially putting a nosecone packed with electronics and recovery systems on top of a motor. A long burn motor like the K300 would be a good choice, but I'd suggest looking into getting a L motor. The K300 in particular has also had some reliability issues in recent years.

10 km with a 75mm motor and rocket is more feasible. It will still require a more optimized airframe than your current design, and most likely would need at least a medium sized M motor, though a higher impulse motor will make things easier.

Take a look at the Tripoli records for K, L and M motors to see what people have done in the past as a point of comparison.

Thank you, I’ll try look around at what 75mm motors I could get my hands on

 

[SuperNova-Rocketry]

For now I’m considering to try whatever height I could possibly achieve with a 54mm and then later scaling up to a 75mm

 

[MClark]

I see you are in the UK.
Where are planning on launching?

 

[SuperNova-Rocketry]

We are currently trying to locate a better launch site, our earlier rockets were launched in a farmers field but we had a close call when one of our high powered rockets landed in a industiral building 500m from our launch site. The industrial building is the only real problem but there is also a road only 300 meters out from the field which the occasional car passes through and we didn’t want to scare any drivers.
We have found a 2km by 2km zone which isn’t very flat but would be a good spot to launch, however I’m not sure who the landowner is and I haven’t been able to find out by all means I’ve tried.

We are currently just searching around google maps for a launch area within a hours drive and we may have found one but we would need to call up the farmers first and find out. I am also asking around in another thread to see if anyone knows a good launch site.

 

[CoyoteNumber2]

Some more ideas in this thread: https://www.rocketryforum.com/threads/minimum-diameter-54mm-lets-see-yours.134594/

10 km on a 54mm is not impossible, but I wouldn't say it's easy either. 6 or 7 km is readily doable.

 

[JohnCoker]

10 km on a 54mm is not impossible, but I wouldn't say it's easy either. 6 or 7 km is readily doable.

A single motor is going to be tough; you'll probably need to go 2-stage. (Clustering might work, but you will add weight and drag.)

To get an idea of how different thrust curves affect velocity and altitude, you can compare how all possible single 54mm motors might work:
https://www.thrustcurve.org/motors/guide/65d77613683ead0002842403/summary.html

 

[SuperNova-Rocketry]

A single motor is going to be tough; you'll probably need to go 2-stage. (Clustering might work, but you will add weight and drag.)

To get an idea of how different thrust curves affect velocity and altitude, you can compare how all possible single 54mm motors might work:
https://www.thrustcurve.org/motors/guide/65d77613683ead0002842403/summary.html

How would you recommend to go about a 2 stage rocket as (I’m not sure why) whenever I add a second stage in openrocket with a fast burning motor it tends to make the apogee even lower than before, not sure if it’s a error or something I’m doing wrong

 

[lr64]

I'm pretty sure that in the US, if you wanted to find out who owned a lot, you could just go down to City Hall. I seem to remember looking up my own property there. I'd be surprised if you don't have something similar in the UK.
-----------
As someone from the RC sailplane world, I look at these rockets and see a lack of aerodynamic sophistication. If you're only going 5 or 10 km, you will have significant air drag all the way. I'd want to make a rocket that looked like it had a very long nose cone, with no breaks, so as to preserve laminar flow as long as possible. A boat tail might help quite a bit. Of course, if you are going for laminar flow, you will have to do some very careful shaping. That includes using a proper laminar airfoil on the fins and making them very smooth, with little sweep. I'm assuming a long burning motor and subsonic speeds, at least at lower altitudes. It won't matter as much at 30,000 feet as it does at 1,000. If you can't commit to making everything very smooth and exactly shaped, stay with a more conventional approach. Also, try not to launch a laminar rocket through a cloud of bugs!

 

[kjhambrick]

A single motor is going to be tough; you'll probably need to go 2-stage. (Clustering might work, but you will add weight and drag.)

To get an idea of how different thrust curves affect velocity and altitude, you can compare how all possible single 54mm motors might work:
https://www.thrustcurve.org/motors/guide/65d77613683ead0002842403/summary.html

John --

Shucks, I wanted to see how you do it

But when I click on your link, I got a 403 error:


-- kjh

 

[SuperNova-Rocketry]

John --

Shucks, I wanted to see how you do it

But when I click on your link, I got a 403 error:
View attachment 633013

-- kjh

It does not work for me either sadly

 

[cls]

Also, try not to launch a laminar rocket through a cloud of bugs!

Please tell us how you know about this!?

 

[David_Stack]

Please tell us how you know about this!?

My guess is that he's alluding to a prior experience winch launching a R/C sailplane, and the detrimental effect those insect entrails had on his L/D...

 

[cls]

My guess is that he's alluding to a prior experience winch launching a R/C sailplane, and the detrimental effect those insect entrails had on his L/D...

(Please don't step on the straight line)

 

[JohnCoker]

John --

Shucks, I wanted to see how you do it

But when I click on your link, I got a 403 error:

Sorry about that; I did it logged in, so that link only works for me. Here's one I did not logged in:
https://www.thrustcurve.org/motors/guide/65dff538c021750002777210/summary.html

As to how I did it, I used the motor guide to quickly configure a 54mm minimum diameter rocket:
https://www.thrustcurve.org/motors/guide.html

How would you recommend to go about a 2 stage rocket as (I’m not sure why) whenever I add a second stage in openrocket with a fast burning motor it tends to make the apogee even lower than before, not sure if it’s a error or something I’m doing wrong

You probably want a slower-burning motor in the second stage. Drag is proportional to the square of the velocity so going faster doesn't mean higher.
https://www.thrustcurve.org/info/simulation.html

 

[lr64]

Please tell us how you know about this!?

Nothing terribly entertaining, I'm afraid. I know it's a problem with airplanes that have laminar flow wings. On some research flights, they'd take off with paper over the leading edge to keep the bug splats off until the aircraft was higher than the bugs. Apparently, any little bump on a wing can disrupt laminar flow unless the Reynolds number is quite low, which it wouldn't be at Mach 0.5!

One day, I was flying my RC glider in the evening, at a steady speed. When it landed, the condensation showed where the laminar separation bubble was, except for a few spots with irregularities on the leading edge so that the flow went turbulent earlier and there wasn't any condensation.

I haven't noticed bug splats from strong winch launches, though certainly some are faster than cars on the highway. A model's leading edge is smaller than a car's windshield, and the high speed part of the launch doesn't last very long. Splattered bugs on windshields used to be far more common when I was a kid than they are now. Maybe by Mach 1 all the bugs get blown off the rocket?

 

[Gus]

I understand you want to fly very high but your questions are so basic that I think you'd honestly be better off working for a bit on trying to make a B impulse rocket go higher than 551 m (the current U.S. NAR record). Number of stages, motor choices, materials choices, nosecone shape, fin shape, etc are all even more important in such a small rocket that you will learn a great deal, faster, and at a tiny fraction of the cost of what you are currently doing.

As Tim Van Milligan points out, you can always go higher by using a bigger motor. The real question is what can you do to go higher with a specific motor.

 

[cls]

Nothing terribly entertaining, I'm afraid.

... darn, was hoping for a good story or two

Splattered bugs on windshields used to be far more common when I was a kid than they are now.

this has been noticed and is taken seriously by scientists around the world. some think we're looking bug-mageddon. for example, https://www.sciencenews.org/article/insect-crisis-book-threats-population-decline-problem

 

[SuperNova-Rocketry]

I understand you want to fly very high but your questions are so basic that I think you'd honestly be better off working for a bit on trying to make a B impulse rocket go higher than 551 m (the current U.S. NAR record). Number of stages, motor choices, materials choices, nosecone shape, fin shape, etc are all even more important in such a small rocket that you will learn a great deal, faster, and at a tiny fraction of the cost of what you are currently doing.

As Tim Van Milligan points out, you can always go higher by using a bigger motor. The real question is what can you do to go higher with a specific motor.

I see, I’ll try take your advice into account