Low powered 75mm motor for testing

[Lt72884]

It's for an experienced Level 2, no matter how you wish to split hairs on the regulations.

Which takes us back to the mentor issue . . .

exactly. im glad you said this.. And again, ill mention that we have been looking for 8 months and no one wanted to take us under their wing except the rocket forums. All my information has come from here and from posters like yourself. I have learned so much from here.
Thank you for letting me know that the L2200G is for experienced L2's. We are finding that out quickly. i have sent emails to our local club for months now with zero response. Everyone is so busy with jobs and family, that im not blaming them for not wanting to help a university

 

[Lt72884]

It is important for everyone to remember, he has only flown one rocket twice. Once on a H550 cert one , then J270 in the same rocket for cert two. The L2200 will be his 4th flight, ever.

yup. only have 2 flights under my belt right now.

 

[kramer714]

Thank you for the help and that great check list. We have many sims of our rocket with correct weights and measurements. I really do appreciate your help

Thank you for the help and that great check list. We have many sims of our rocket with correct weights and measurements. I really do appreciate your help with this. We have ONE level 2 flight for each of us and thats it. We are NEW L2's. This is not a L3 flight

it is ALMOST a level 3 flight, you are using a 5,102ns motor, an M is 5,120. You are actually within the motor tolerance of an M. Look at the chart from a M2225 and an L2300. heck same case even. I (and the other posters) appreciate that you are new to level 2, that is WHY we are concerned. As a L3CC, I would never sign off on a level 3 built by someone with that little experiance.

If active drag control is your 'experiment' I would think you have a test plan for that - TRL3-TRL6. That should be well integrated into your rocket test plan. The active drag development should be selecting your 'step up motors' I would think.

Mike K

P.S. I have worked control surfaces for aircraft and missiles over the years. Can you post some pictures of your build? and post your sim?

 

[Lt72884]

Thank you for the help and that great check list. We have many sims of our rocket with correct weights and measurements. I really do appreciate your help

it is ALMOST a level 3 flight, you are using a 5,102ns motor, an M is 5,120. You are actually within the motor tolerance of an M. Look at the chart from a M2225 and an L2300. heck same case even. I (and the other posters) appreciate that you are new to level 2, that is WHY we are concerned. As a L3CC, I would never sign off on a level 3 built by someone with that little experiance.

If active drag control is your 'experiment' I would think you have a test plan for that - TRL3-TRL6. That should be well integrated into your rocket test plan. The active drag development should be selecting your 'step up motors' I would think.

Mike K

P.S. I have worked control surfaces for aircraft and missiles over the years. Can you post some pictures of your build? and post your sim?


View attachment 568672

Im SUPER glad you and others are telling me not to launch and to wait. I told my team last night and the filed that i would rather wait and launch when we have tested everything because NO ONES LIFE is worth it. its way way to dangerous.

Attached is our sim of the rocket. Can i send the Images of our ADS idea to you in a private message?

also, the launch information has been set to default so others can change it to wahtever they want on this file. i forgot to mention that

 

[cjl]

yup. only have 2 flights under my belt right now.

An L2200 is a *very* serious motor and has a lot of energy. I would be very hesitant to sign off on a flight if I were an RSO that was someone's third flight ever using a motor that, for all intents and purposes, might as well be an M. Hell, the L2200 is in many ways more violent than a baby M and more demanding on the rocket.

I would highly suggest doing some J or K flights with 38 or 54mm, electronics, etc to gain some experience. Many of the questions you've been asking here indicate a concerning lack of knowledge for someone basically doing an L3 (since anything that can fly on an L2200 can likely also fly on an M1297).

You may be able to somewhat bypass this if you have an experienced mentor supervising you, but at your current level of experience without a mentor, I am very concerned. Is there someone from the local club who's either an experienced L2 flyer with 75mm experience or an L3 who could help you out?

 

[Banzai88]

PLEASE dont try to assemble the motor (or even open up the bags) until / unless you have an experienced flyer helping you.

....AND have the instructions in hand. I'm concerned that if you got no instructions that the bag with all the o-rings and small.parts might be incomplete.....and that would be dangerous.

 

[firemanup]

....AND have the instructions in hand. I'm concerned that if you got no instructions that the bag with all the o-rings and small.parts might be incomplete.....and that would be

He may not understand they are in the sealed bag.

 

[Lt72884]

An L2200 is a *very* serious motor and has a lot of energy. I would be very hesitant to sign off on a flight if I were an RSO that was someone's third flight ever using a motor that, for all intents and purposes, might as well be an M. Hell, the L2200 is in many ways more violent than a baby M and more demanding on the rocket.

I would highly suggest doing some J or K flights with 38 or 54mm, electronics, etc to gain some experience. Many of the questions you've been asking here indicate a concerning lack of knowledge for someone basically doing an L3 (since anything that can fly on an L2200 can likely also fly on an M1297).

You may be able to somewhat bypass this if you have an experienced mentor supervising you, but at your current level of experience without a mentor, I am very concerned. Is there someone from the local club who's either an experienced L2 flyer with 75mm experience or an L3 who could help you out?

you and me both. I am concerned as well, and im feeling the pressure from the school and the capstone committee. Its alot of unwanted stress. I have told them we have to be safe or we could ruin it for the field and other launchers... hey, maybe this is why its hard to find a mentor?

 

[kramer714]

FYI adapter 54-75

 

[Voyager1]

These are things that most people would assume to be common knowledge among level 2 holders. It is pretty scary you can buy a motor and don't know about the proper hardware for it.

Indeed!

 

[Sooner Boomer]

Your comments in previous messages have me concerned that you may be confused about rocket construction. First, motors are designated by a nominal diameter. Nominal means "this is what we call it, even though it may not be the exact size". A 75mm motor may not be *exactly* 75mm in diameter, but it will be very close. Second, motor mount tubes. These may be cardboard, phenolic, or fiberglass (or maybe even carbon fiber). They are sized so that a motor will slide inside them. a 75mm motor mount tube is just over 75mm in inside diameter, so that a 75mm motor (single use or reloadable) will fit inside. Some pictures (these are using a 38mm motor - I don't have a 75mm at hand).

A RMS casing (reloadable), and an DMS (single use)


They will both fit inside the same motor mount tube (washers are for motor retention)



A motor inside a motor mount tube (this motor mount will go in a rocket I'm now building).


Bonding grains, liners, etc - a good video:

 

[Voyager1]

It is important for everyone to remember, he has only flown one rocket twice. Once on a H550 cert one , then J270 in the same rocket for cert two. The L2200 will be his 4th flight, ever.

This does my head in! Our club has mentored and provided a certification facility to several uni teams over the last few years. There appears to be a blind obsession with achieving HPR certification with the least amount of experience. Most of us learn and gain experience over several years. Granted that these students have a limited time in which to achieve their goals, but it does come at a cost to the regular flyers and clubs providing the service. It seems to me that any institution encouraging their students to pursue these projects should be a little more proactive in seeking experienced mentors.

I don't know what the experience requirements are over there prior to certifying through the HPR levels, but over here most clubs have a mandatory minimum number of successful flights and builds at a level before any certification can happen. Our club has a 5 flight minimum at each level prior to certifying to the next. Additionally, some clubs here also have a mid power assessment process with similar requirements at low power before allowing the use of F an G motors.

 

[Banzai88]

He may not understand they are in the sealed bag.

That fact alone should give everyone a moment of concern!

OP needs to review what they have to see if they have a complete reload kit.

 

[Handeman]

... hey, maybe this is why its hard to find a mentor?

The reason you are having a hard time with finding mentors is because, like almost all university programs, you are basically L0 fliers with zero rocketry experience trying to fly L3 projects.
The fact that you don't understand the difference between single use motors, reloadable motors, motor tubes and how they all work is a huge red flag. Someone just starting to fly E-G motors would have that knowledge.

Your professors and you, are good with what is written on paper, but none of you have any practical experience with rockets and you don't understand the basics that are learned flying small Estes type rockets and then working up through mid-power, L1 and finally into L2 level rockets. That experience and knowledge is gained over years of building and flying. Any mentor to a university program is going to be responsible for providing years of experience to a program that is lasting 1 or maybe 2 semesters. It's not surprising nobody wants to take that on with the commitment in time and effort that requires. That especially applies to capstone projects.

When a university has a rocketry program that is ongoing and the underclassmen can learn from the seniors and there is some passing on of knowledge, although in most cases it isn't much, that isn't so bad, but capstone projects are usually from the ground up in a few months. The fact that unknowledgeable professors expect unknowledgeable students to complete projects that are so far beyond their knowledge and experience is something I find very disturbing.

 

[Rocketjunkie]

Grain bonding is really only needed for high acceleration flights. I flew most of these motors before grain bonding was introduced with no issues including L2500, several K2050s, lots of high thrust 75/3860, and Warp9 loads. However, never in minimum diameter rockets. I like long burns for minimum diameter rockets as you get much higher altitude for the same impulse. An L2200 to under 10K feet implies a rocket about 6" diameter and probably over 30 lb. without the motor. You can talk with Aerotech about this and find out for sure.

 

[Handeman]

This does my head in! Our club has mentored and provided a certification facility to several uni teams over the last few years. There appears to be a blind obsession with achieving HPR certification with the least amount of experience. Most of us learn and gain experience over several years. Granted that these students have a limited time in which to achieve their goals, but it does come at a cost to the regular flyers and clubs providing the service. It seems to me that any institution encouraging their students to pursue these projects should be a little more proactive in seeking experienced mentors.

I don't know what the experience requirements are over there prior to certifying through the HPR levels, but over here most clubs have a mandatory minimum number of successful flights at a level before any certification can happen. Our club has a 5 flight minimum at each level prior to certifying to the next. Additionally, some clubs here also have a mid power assessment process before allowing the use of F an G motors.

I totally agree with what you are saying. It pretty much mirrors what has been happening at our club. We don't have the flight requirements for advancement, but that is a really good idea I'll bring up to our BOD.
We have 5 different IREC and SAC teams from various organizations that fly at our site. The individual certifications haven't really been the issues. It's a team of 30 showing up with only 2 or 3 that are certified or ever flown a rocket before, and they want to fly a L3 project to over 10,000 ft.

 

[Rocketjunkie]

For testing, you can use either a 2 grain such as a K1000T or K1800ST. You can go even smaller with the 1 grain K750ST.

 

[Lt72884]

The reason you are having a hard time with finding mentors is because, like almost all university programs, you are basically L0 fliers with zero rocketry experience trying to fly L3 projects.
The fact that you don't understand the difference between single use motors, reloadable motors, motor tubes and how they all work is a huge red flag. Someone just starting to fly E-G motors would have that knowledge.

Your professors and you, are good with what is written on paper, but none of you have any practical experience with rockets and you don't understand the basics that are learned flying small Estes type rockets and then working up through mid-power, L1 and finally into L2 level rockets. That experience and knowledge is gained over years of building and flying. Any mentor to a university program is going to be responsible for providing years of experience to a program that is lasting 1 or maybe 2 semesters. It's not surprising nobody wants to take that on with the commitment in time and effort that requires. That especially applies to capstone projects.

When a university has a rocketry program that is ongoing and the underclassmen can learn from the seniors and there is some passing on of knowledge, although in most cases it isn't much, that isn't so bad, but capstone projects are usually from the ground up in a few months. The fact that unknowledgeable professors expect unknowledgeable students to complete projects that are so far beyond their knowledge and experience is something I find very disturbing.

this is exactly why we cant find mentors and i have spent sooo much time on the forums. We are excellent with paper stuff and we SUCK at practicle and its makes me sad. I do not have the money to do this outside of school in the first place cuz school is so expensive haha.
I was talking to someone else and ORIGINALLY the school wanted us to do a L3 rocket from scratch, spaceport americaup, 20k flight, and an active drag system. I told them that was way to much to do, so they chopped it down to a L2 10k flight with an ADS and next year the new students will take the same rocket to spaceport, but next years students will be in the same boat as us haha

 

[mikec]

If you look at the OP's .ork file, this is a 4" Extreme Wildman with 9# of weight in the nose cone, total dry mass of almost 29# (my L3 Extreme Wildman was more like 15# dry.) Even so, keeping it under 10K with an L2200 is going to be tough. And this thing is so heavy that none of the available single-use motors will work great; L1000, for example, only gets it to 4000-ish feet.

 

[Lt72884]

For testing, you can use either a 2 grain such as a K1000T or K1800ST. You can go even smaller with the 1 grain K750ST.

i suggested that motor to the team. They are looking it over. We may need to buy a differnt case for it since we have the 75/5120 that fits an L2200G

 

[Lt72884]

If you look at the OP's .ork file, this is a 4" Extreme Wildman with 9# of weight in the nose cone, total dry mass of almost 29# (my L3 Extreme Wildman was more like 15# dry.) Even so, keeping it under 10K with an L2200 is going to be tough. And this thing is so heavy that none of the available single-use motors will work great; L1000, for example, only gets it to 4000-ish feet.

that 9lb is to simulate spaceport america cup rules. We will have 9lb payload but i dont think it will be in the nosecone. thanks for pointing that out. We will put the payload in teh appropriate place

 

[Lt72884]

I totally agree with what you are saying. It pretty much mirrors what has been happening at our club. We don't have the flight requirements for advancement, but that is a really good idea I'll bring up to our BOD.
We have 5 different IREC and SAC teams from various organizations that fly at our site. The individual certifications haven't really been the issues. It's a team of 30 showing up with only 2 or 3 that are certified or ever flown a rocket before, and they want to fly a L3 project to over 10,000 ft.

our EXACT scenario but only with 5 members rather than 30

 

[mikec]

that 9lb is to simulate spaceport america cup rules. We will have 9lb payload but i dont think it will be in the nosecone. thanks for pointing that out. We will put the payload in teh appropriate place

All that will do is help to reduce the massive overstability you would have with the mass in the nose. It still makes the rocket something of a pig, will load the shock cords more, you'll need a bigger chute, etc. If I resim with everything set to unfinished (you had polished), it sims to about 9000 feet on the L2200.

 

[Neutronium95]

With SAC, don't you need at least a 6" tube to fit the minimum dimensions of the cubesat form factor they want you to use?

 

[Rocketjunkie]

Go with a slightly smaller motor. L1940X has 4329 N-s but fits the 75/3840 case but you can use yours with 1 spacer if you have the correct forward closure. I've flown these in my 7.5" goblin (built before the kits came out and main in nose https://www.rocketryforum.com/threads/almost-a-goblin.8709/ ).

 

[user 30299]

With SAC, don't you need at least a 6" tube to fit the minimum dimensions of the cubesat form factor they want you to use?

You only need the 6" tube if you want to get "extra points" for having a payload that fits the cubesat form.

As long as you have a payload that is 4kg (8.8 lbs.) - you're good to go.

The boiler plate load has the cubesat dimension conditions.

 

[Lt72884]

All that will do is help to reduce the massive overstability you would have with the mass in the nose. It still makes the rocket something of a pig, will load the shock cords more, you'll need a bigger chute, etc. If I resim with everything set to unfinished (you had polished), it sims to about 9000 feet on the L2200.

the mass in the nose is the one that we will move around. its supposed to be teh 9lb payload cubesat thing, but we put it in the nose for some reason. we will find a better spot for that. Maybe even take out the 9lbs all together.

our stability is almost 8 right now. Im affraid the rocket will cone spirial... i think thats the term

 

[cls]

Clearly the OP and team have been rooked by the incompetent bozo professors that set out this "challenge", provide no support, training, guidance, experience... nor lectures abut rocketry basics (static and dynamic stability ,commercially available materials, etc)

I've seen this before. Mentored several university SLI teams, profs did not even offer independent study credits for the effort! ought to be at least 3 units for 2 semesters, considering the effort involved.

I think that's why everyone they contacted ran away. unless I have full control over the skills and knowledge development for at least 2 semesters, and a realistic budget including travel... no, I am not mentoring at this level.

and, as mentioned above, a "live" program works with incoming freshmen and sophmores not just the graduating seniors.... who disappear with their hard won knowledge...

the whole thing stinks.


the folks that replaced me for one SLI mentoring slot had a differernt approach: success at any cost. so everything was improvised, provisional, emergency, here kid I'll do it for you. That does not match my goals of developing functioning, capable adults.

i'll stop here.

 

[Lt72884]

Clearly the OP and team have been rooked by the incompetent bozo professors that set out this "challenge", provide no support, training, guidance, experience... nor lectures abut rocketry basics (static and dynamic stability ,commercially available materials, etc)

I've seen this before. Mentored several university SLI teams, profs did not even offer independent study credits for the effort! ought to be at least 3 units for 2 semesters, considering the effort involved.

I think that's why everyone they contacted ran away. unless I have full control over the skills and knowledge development for at least 2 semesters, and a realistic budget including travel... no, I am not mentoring at this level.

and, as mentioned above, a "live" program works with incoming freshmen and sophmores not just the graduating seniors.... who disappear with their hard won knowledge...

the whole thing stinks.


the folks that replaced me for one SLI mentoring slot had a differernt approach: success at any cost. so everything was improvised, provisional, emergency, here kid I'll do it for you. That does not match my goals of developing functioning, capable adults.

i'll stop here.

yup, we have had no support, no lectures on rocketry, no books, no nothing. I actually went out and got the model rocektry handbook and gave it to the professor at my own cost.
It almost makes me feel stupid in a way because i know literally nothing except the small L2 j270 i used

 

[Voyager1]

Just a few comments on your sim file after a quick review. As received, it requires a little modification to at least these parameters:

• Launch rail length of 100 cm? For a rocket this size you probably should be using a 3 m rail.
• Ground hit velocity of 8.77 m/s is a little high. Might need to increase your main chute size or CD.
• Perhaps with a rocket this size and expected apogee, you could consider redundant altimeters?
• Your forward launch lug position could move forward a bit more, closer to your CoG.
• Your drogue deployment is set at 1st ejection charge. Set it at apogee.
• Your main deployment is set at 1st ejection charge. Set it at specific altitude during descent, say between 500'-1,000'.

There might be more issues. However, it's good that you are using a well known kit, rather than scratch building. Don't forget to account for additional masses and their positions, e.g., epoxy, etc.