Is this a good idea?

[alyssdelga000]

Hello and I hope you are all well. I am new to this community and the art of constructing rockets.
I have an assignment in one of my classes where the objective is to reach a mile, while carrying a 1lb payload. The question I have is whether a blue tube would allow me to reach this altitude, or should I consider an LOC tube. We are using a Hammerhead J835 motor in this assignment. I was also wondering if a 4in diameter would cause my rocket to be too heavy and not reach the mile. Should I aim for a lower diameter. Please let me know it would be so so so greatly appreciated.

Thank you!

​

 

[Titan II]

Start here....

https://openrocket.info/

 

[smstachwick]

Hello and I hope you are all well. I am new to this community and the art of constructing rockets.
I have an assignment in one of my classes where the objective is to reach a mile, while carrying a 1lb payload. The question I have is whether a blue tube would allow me to reach this altitude, or should I consider an LOC tube. We are using a Hammerhead J835 motor in this assignment. I was also wondering if a 4in diameter would cause my rocket to be too heavy and not reach the mile. Should I aim for a lower diameter. Please let me know it would be so so so greatly appreciated.

Thank you!

​

First things first: Purchasing a J motor (usually) requires a Level 2 high power certification, or a Level 1 certification in the case of a flight made to obtain Level 2 certification. Does anybody on your team have either of those qualifications?

 

[Hobie1dog]

Welcome to The Forum and great German Shepherd dog in your avatar.

 

[Titan II]

First things first: Purchasing a J motor requires a Level 2 high power certification, or a Level 1 certification in the case of a flight made to obtain Level 2 certification. Does anybody on your team have either of those qualifications?

That is not always true.

 

[boatgeek]

See responses above regarding supervision if you're not part of a university class.

A J motor is a little light to take a 1-lb payload to a mile on a 4" rocket. It's probably possible, but you'll want your rocket to be as light as possible (probably LOC high power tube and 1/8" plywood fins). As noted above, start fooling around in OpenRocket to get an answer. You can start with a 4" LOC kit's OR file if you want to make your job a little easier.

 

[mikec]

A J motor is a little light to take a 1-lb payload to a mile on a 4" rocket.

Despite the name, the OP seems to be talking about the Hypertek J series 835mm tank motor, which goes up to K total impulse (K240.)

Using hybrid motors without much experience or supervision doesn't seem like a great idea to me, but here we are. Possibly this is a SystemsGo class? https://www.systemsgo.org/

 

[boatgeek]

Despite the name, the OP seems to be talking about the Hypertek J series 835mm tank motor, which goes up to K total impulse (K240.)

Using hybrid motors without much experience or supervision doesn't seem like a great idea to me, but here we are. Possibly this is a SystemsGo class? https://www.systemsgo.org/

OK, that makes more sense. And I definitely share your concerns about hybrids and lack of experience.

 

[smstachwick]

That is not always true.

Thank you. Edited.

 

[Scott_650]

Despite the name, the OP seems to be talking about the Hypertek J series 835mm tank motor, which goes up to K total impulse (K240.)

Using hybrid motors without much experience or supervision doesn't seem like a great idea to me, but here we are. Possibly this is a SystemsGo class? https://www.systemsgo.org/

Here’s the skinny on the Hypertek Hybrids - looks like a fun motor! http://www.hypertekhybrids.com/prodjseries.html

Going by the linked chart on the Hypertek site that motor can lift 1622 grams/3.6 pounds so this is going to need a fairly light rocket to do the job. My guess is the rocket will need to be as small a diameter as possible to hold the hardware and payload. I don’t know the relative mass of blue tube vs kraft tube. What condition does the rocket have to be after recovery? Is it a requirement that it be flyable again? Hopefully the OP keeps us updated.

 

[mikec]

The OP has all the hallmarks of a SystemsGo student. They show up here from time to time asking basic questions, which always makes me wonder how SystemsGo is actually taught. Maybe someone has experience with them? https://www.systemsgo.org/ They do seem to be keeping Hypertek production going at some level.

 

[mikec]

Going by the linked chart on the Hypertek site that motor can lift 1622 grams/3.6 pounds

That's the loaded weight of the motor, not what it can lift. A K240 can fly a 6#-dry rocket to a little under 6000 feet according to thrustcurve.

 

[alyssdelga000]

First things first: Purchasing a J motor (usually) requires a Level 2 high power certification, or a Level 1 certification in the case of a flight made to obtain Level 2 certification. Does anybody on your team have either of those qualifications?

To answer your question no, no one has either certification. The way that our curriculum is formatted, we designed our Level 1 certification rocket, and we are now designing this rocket. We will not begin constructing this rocket until we have constructed our Level 1 certification rocket. Which will not be until March. But we still need to design this rocket regardless of whether we have out certification or not.

Again, would a 4in diameter be a good idea, and would blue tube be too heavy?

 

[mikec]

If you're using the Hammerhead tank, then the tank diameter is 81mm and won't fit in anything smaller than 4 inches anyway.

My quick sim results are above. If the rocket weight is under 6 pounds or so this should be doable.

Don't you have mentors you can ask these questions of? I'm not sure what the rules of your program are but I don't think the forum should facilitate, well, cheating.

 

[alyssdelga000]

If you're using the Hammerhead tank, then the tank diameter is 81mm and won't fit in anything smaller than 4 inches anyway.

My quick sim results are above. If the rocket weight is under 6 pounds or so this should be doable.

Don't you have mentors you can ask these questions of? I'm not sure what the rules of your program are but I don't think the forum should facilitate, well, cheating.

Thank you to everyone who has given me input! (I am a senior in high school taking a rocket engineering course) Just to answer any questions asked about what course this is for. I hope my questions have not implied I am trying to cheat or anything similar to that.
I am working in a group and have done my own research. But these were questions my group and I were having issues coming to an agreement on.
I was simply trying to seek the opinions of others who have had more hands on experience. My teacher will rarely answer specific questions like these, and encourages us to find answers on our own. Which is great, but often challenging.
We are going to change to an LOC tube with the same diameter, and have our fins be a 1/8 thickness. I will give updates on our construction and soon the actual launch. Thank you to everyone!

 

[Carlostenteria]

Thank you to everyone who has given me input! (I am a senior in high school taking a rocket engineering course) Just to answer any questions asked about what course this is for. I hope my questions have not implied I am trying to cheat or anything similar to that.
I am working in a group and have done my own research. But these were questions my group and I were having issues coming to an agreement on.
I was simply trying to seek the opinions of others who have had more hands on experience. My teacher will rarely answer specific questions like these, and encourages us to find answers on our own. Which is great, but often challenging.
We are going to change to an LOC tube with the same diameter, and have our fins be a 1/8 thickness. I will give updates on our construction and soon the actual launch. Thank you to everyone!

That sounds interesting, welcome)