Low powered 75mm motor for testing

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Lt72884

Lt72884

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Just received word from our field that we need to test our rocket first with a low powered L2 motor before we can use the L2200 for a 10K flight. Their reasoning is good. They want us to make sure that our simulated data matches accurately to an actual flight so we dont break the waiver of 10K and cause serious issues with the FAA since its right below flight paths to the air ports.
I do not have much familiarity with all motors, and i know i could use open rocket to find one, which i will use to test, i just need a recommendation for a starting point. What K or L motors have you guys used that are good and below 8000 feet?

thanks
 
Lt72884 said:
Just received word from our field that we need to test our rocket first with a low powered L2 motor before we can use the L2200 for a 10K flight. Their reasoning is good. They want us to make sure that our simulated data matches accurately to an actual flight so we dont break the waiver of 10K and cause serious issues with the FAA since its right below flight paths to the air ports.
I do not have much familiarity with all motors, and i know i could use open rocket to find one, which i will use to test, i just need a recommendation for a starting point. What K or L motors have you guys used that are good and below 8000 feet?

thanks
Click to expand...

This is far too open ended of a question.

As you are building a rocket, you should be familar with the process of performing simulations using simulation software. This includes inputting accurate data, such as weights, exacting measurements, etc., to help give you the best output possible. Sure, there are flukes here and there. But to simply ask what folks have flown to 8000ft or less is far too open ended of a question. Tom Cohen has built and flown rockets that have flown to all of 800 feet on O motors... But then other individuals have flown O motors to 40k+. I can fly a K or L motor to 14k all day long. I can also design and build a rocket that will fly to 800 feet all day.

If you're needing to use a low powered L2 motor, then a K or L motor is not the motor you want to use. You want to use a J motor. Based on the fact that your 10k flight uses an L2200, I would think you can use almost any J motor available on the market. But again, do your due diligence and then come back and ask for recommendations.

If you are working on getting L3, you should be able to calculate these simulations on your own and make confident decisions on safe motor selection for your flights. Coming to RocketryForum and asking for insight on what smaller motor to use to fly to less than 8000 feet does not instill a sense of confidence in me... And I'm not even a TAP.
 
mrwalsh85 said:
This is far too open ended of a question.

As you are building a rocket, you should be familar with the process of performing simulations using simulation software. This includes inputting accurate data, such as weights, exacting measurements, etc., to help give you the best output possible. Sure, there are flukes here and there. But to simply ask what folks have flown to 8000ft or less is far too open ended of a question. Tom Cohen has built and flown rockets that have flown to all of 800 feet on O motors... But then other individuals have flown O motors to 40k+. I can fly a K or L motor to 14k all day long. I can also design and build a rocket that will fly to 800 feet all day.

If you're needing to use a low powered L2 motor, then a K or L motor is not the motor you want to use. You want to use a J motor. Based on the fact that your 10k flight uses an L2200, I would think you can use almost any J motor available on the market. But again, do your due diligence and then come back and ask for recommendations.

If you are working on getting L3, you should be able to calculate these simulations on your own and make confident decisions on safe motor selection for your flights. Coming to RocketryForum and asking for insight on what smaller motor to use to fly to less than 8000 feet does not instill a sense of confidence in me... And I'm not even a TAP.
Click to expand...
this is for a L2 flight not an L3 flight. this will be our 3rd rocket flight. I do get that this is an open ended question. I was just looking for a starting point:) I do use open rocket alot, just wanted some real world answers from people who have flown on specific motors
The k560 was recommended so i will start there. open rocket motor DB says none of the J's are 75mm.
 
tsmith1315 said:
Are you planning to make a 10k' flight at a field with a 10k' waiver?
Click to expand...
no, just close to 10k. roughly 9500. The president of the club mentioned that if it were to go to 10,100, we would be ok, but before the flight, they want the rocket tested and approved by a tap member since we have an active drag system on it.
 
ok, based off of the recommendations, i have narrowed it down to 4 motors. From here, i am good. thanks for the help.
 
QFactor said:
That motor would also require the Stainless Steel forward seal disc.

Being a Super Thunder motor, would it also need grain bonding?
Click to expand...
whats grain bonding and will i have to do this on my L2200 motor that we purchased? Its a 4 grain motor setup
 
Lt72884 said:
whats grain bonding and will i have to do this on my L2200 motor that we purchased? Its a 4 grain motor setup
Click to expand...
It's bonding the propellant grains to the liner, usually with Elmer's Glue-All Max. It prevents upper grains from collapsing onto the lower ones during high acceleration and causing a CATO. Ask Aerotech or look at the documentation included with the motor to see if the L2200 requires grain bonding. If grain bonding is needed, there will be an instruction sheet inside the parts bag describing the process.
 
Lt72884 said:
whats grain bonding and will i have to do this on my L2200 motor that we purchased? Its a 4 grain motor setup
Click to expand...
If your motor requires grain bonding, it will have the instructions on how to do it included with the motor. Some folks do it as a matter of course, some debate on the necessity of doing so on motors that AT does not specifically instruct to do so.

AT instructional resources located here: https://www.rocketmotorparts.com/page/aerotech-resources
 
Banzai88 said:
If your motor requires grain bonding, it will have the instructions on how to do it included with the motor. Some folks do it as a matter of course, some debate on the necessity of doing so on motors that AT does not specifically instruct to do so.

AT instructional resources located here: https://www.rocketmotorparts.com/page/aerotech-resources
Click to expand...
Please get a mentor that’s at least an L2 and has some semblance of being able to help you with these most basic elements of flying HP
 
sharkbait said:
Please get a mentor that’s at least an L2 and has some semblance of being able to help you with these most basic elements of flying HP
Click to expand...
I'm thinking that you meant to direct that to the OP(??), since I'm already an L2 working my L3 project!

I agree, they're in SERIOUS need of a local mentor, a LOT more experience, and a broader spectrum of resource awareness and usage.
 
Unfortunately I don't think the Aerotech instructions on the website call out which motors need to be grain-bonded, AT handles this by putting an insert into the reload kit (which can be an unpleasant surprise if you assemble motors at the launch site). Per the advisory at http://web.archive.org/web/20181222033732/http://aerotech-rocketry.com/news.aspx?y=2016 the following motors have to be bonded:

75mm
K1000T, L1520T, L2200G, M1500G, M1780NT

98mm
L1500T, M2400T, L2500ST, M4500ST, M1845NT, M2100G, M2500T, M2000R, M6000ST, N2000W, N3300R, N2200DM

There may be others released after 2016 that also need this, ST probably.
 
sharkbait said:
Please get a mentor that’s at least an L2 and has some semblance of being able to help you with these most basic elements of flying HP
Click to expand...
i would not call grain bonding basic. It was never ever covered in my L1 or L2 flights or written exams for my L2. If it is basic, then it needs to be covered more.

We do not have very many mentors, if any, in our area willing to spend the time to help the university out on this project. We started searching and asking sept 2022 and received very little feed back from locals. As soon as they find out its for a school senior engineering project, they all scramble, leaving us to be on our own. Even the one selling the motors to us never mentioned grain bonding.

all the stuff i have learned about HPR has been from these forums and posters such as yourself. Its been very very very helpful.
 
Last edited:
Banzai88 said:
I'm thinking that you meant to direct that to the OP(??), since I'm already an L2 working my L3 project!

I agree, they're in SERIOUS need of a local mentor, a LOT more experience, and a broader spectrum of resource awareness and usage.
Click to expand...
i agree, but none wanted too. as soon as they find out its for a university, they scramble., everything i have learned about HPR has been from here. So far, i think we have done pretty good for the amount of time we have had. Nothing about grain bonding was ever covered in our written L2 exam, so i wouldnt call it basic or common knowledge, hence the reason for a mentor, but since that is slim to none, i asked on here hoping to get the correct guidence, and i did, which was great:)
 
mikec said:
Unfortunately I don't think the Aerotech instructions on the website call out which motors need to be grain-bonded, AT handles this by putting an insert into the reload kit (which can be an unpleasant surprise if you assemble motors at the launch site). Per the advisory at http://web.archive.org/web/20181222033732/http://aerotech-rocketry.com/news.aspx?y=2016 the following motors have to be bonded:

75mm
K1000T, L1520T, L2200G, M1500G, M1780NT

98mm
L1500T, M2400T, L2500ST, M4500ST, M1845NT, M2100G, M2500T, M2000R, M6000ST, N2000W, N3300R, N2200DM

There may be others released after 2016 that also need this, ST probably.
Click to expand...
ok, great information. so someone new to this who has only done the L2 written exam and used a j270 would be hosed then haha. Hence why i asked here and got some excellent answers, such as yours. thanks for that information. it helps alot.
 
Last edited:
Lt72884 said:
ok, great. so someone new to this who has only done the L2 written exam and used a j270 would be hosed then haha. Even the local supplier of the motors never mentioned grain bonding to us. Hence why i asked here and got some excellent answers, such as yours. thanks for that information. it helps alot.
Click to expand...
To be fair, there are like 20-25 motors TOTAL amongst the hundreds of motors available that require grain bonding, and they are all in the Upper L2/Lower L3 power band.....so it's not likely that anyone new or new-ish is going to have any clue about it, nor is the vendor likely to mention it until/unless you are actually purchasing one of those motors.
 
Lt72884 said:
ok, great. so someone new to this who has only done the L2 written exam and used a j270 would be hosed then haha. Even the local supplier of the motors never mentioned grain bonding to us. Hence why i asked here and got some excellent answers, such as yours. thanks for that information. it helps alot.
Click to expand...

Banzai88 said:
To be fair, there are like 20-25 motors TOTAL amongst the hundreds of motors available that require grain bonding, and they are all in the Upper L2/Lower L3 power band.....so it's not likely that anyone new or new-ish is going to have any clue about it, nor is the vendor likely to mention it until/unless you are actually purchasing one of those motors.
Click to expand...
And again... motors that require it come with a document saying so and providing instructions on how to do it. Saying you'd be "hosed" is disingenuous. It's not hard. If you can epoxy a coupler into a body tube, you can do grain bonding.

And just because it's driving me crazy when I read your posts, "a lot" is two words.
 
Banzai88 said:
To be fair, there are like 20-25 motors TOTAL amongst the hundreds of motors available that require grain bonding, and they are all in the Upper L2/Lower L3 power band.....so it's not likely that anyone new or new-ish is going to have any clue about it, nor is the vendor likely to mention it until/unless you are actually purchasing one of those motors.
Click to expand...
Thanks for this. I agree. We did purchase the L2200G and was told nothing of grain bonding or what hardware we needed. We were also never told that we needed to buy a tube to hold it all together, so when we looked at the motor grains, and noticed we had a cardboard motor mount, we figured something was wrong. Called the local supplier and they informed us we needed to buy an $800 tube to hold all the grains. So we did.
But now the field wants us to use a smaller motor so i think we are going for the K1000 or L1150 for lower flight.
 
Antares JS said:
And again... motors that require it come with a document saying so and providing instructions on how to do it. Saying you'd be "hosed" is disingenuous. It's not hard. If you can epoxy a coupler into a body tube, you can do grain bonding.

And just because it's driving me crazy when I read your posts, "a lot" is two words.
Click to expand...
haha, its like colour or color. but you are correct, alot is 2 words.
we looked in the boxes and none of the instructions say we need to grain bond it.. So maybe it was not packed, which is a possibility.

i know its not hard, its just to keep them from sliding based on your other post. When i say hosed, i mean if we didnt do that because we were unaware of it due to no instructions, such as ours, then therefore it could CATO as you speak.
edit. i went and re-read my post and it seems i had two replies mashed into one. Probably why it seemed contradictive of what i said. i have now fixed that haha
 
i now know what grain bonding is, and will be contacting the motor supplier for instructions for our motor if needs be. Thanks.
This thread can be closed or locked if needs be:) i have learned lots and lots from you guys and grateful for it.
 

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