Copying a Kit

[Who_Cares]

I guess no one else is going to point this out, but I hate seeing things like this. Entering grumpy old man mode...

The LOC IV is designed for F through H motors. Putting a J motor in it with potentially four times the total impulse it was designed for, without extensive mods, is just not a good idea. It doesn't seem you learned anything from this experience. I hope whomever went through your level 2 checklist learned something--that they did a poor job "assisting" you to have a failure.

Stay with level 1 for a while, and work on learning how to do things right. Many of these mishaps happen to people who push the envelop before they are ready. When you do think about level 2, look at legitimate level 2 rockets instead of just "Put a J420 in your LOC IV and let er rip".
View attachment 379292 .

I respectfully disagree with your opinion. I have seen some people on the internet say they certified level 2 with a LOC IV. It is also not unusual to hear of people certifying level 2 with similar LOC kits. Even with this information I knew a J270W was going to be pushing it (the J270W was not my first choice, but I wanted to use a single use motor with an ejection charge). A J94 would have been ideal, but it is a plugged motor so I would have needed to use electronics and an ejection charge.

The main issue is that apparently the LOC IV used to ship with 1/4" plywood fins. However, now they ship with 1/8th" fins (I did not find this out until after the flight attempt). The airfame remained in near perfect condition even with the fins shearing at above mach 0.5 (the joints did not fail, the plywood itself failed) creating a sudden roll.

Anyways that is also why I am likely going to glass the entire airframe which would alleviate your concerns.

 

[Tim51]

I respectfully disagree with your opinion. I have seen some people on the internet say they certified level 2 with a LOC IV. It is also not unusual to hear of people certifying level 2 with similar LOC kits. Even with this information I knew a J270W was going to be pushing it (the J270W was not my first choice, but I wanted to use a single use motor with an ejection charge). A J94 would have been ideal, but it is a plugged motor so I would have needed to use electronics and an ejection charge.

The main issue is that apparently the LOC IV used to ship with 1/4" plywood fins. However, now they ship with 1/8th" fins (I did not find this out until after the flight attempt). The airfame remained in near perfect condition even with the fins shearing at above mach 0.5 (the joints did not fail, the plywood itself failed) creating a sudden roll.

Anyways that is also why I am likely going to glass the entire airframe which would alleviate your concerns.

As per my signature, I did my L2 with an unglassed Loc Fantom (a 4" 38mm set up similar to the Loc IV). Everything went to plan. I did 'feel' at the time a 6G 38 motor was somehow the limit to that kind of construction, although the MMT supplied is long enough to take a 6GXL, but I hear different opinions on that. I subsequently lost that booster section on a later flight to a cato, and rebuilt with a 'glass wrap. Just my £0.02...

 

[grouch]

So in the end, if the rocket breaks then there is a learning opportunity. I think it would be fun to mod the LOC 4 to be a solid L2 rocket. This assumes you are ok with the range of motors available in 38mm.

The rub is you need enough experience to know what to change. Simply caking on epoxy is not the ticket either. I personally think mid power rockets for L1 and L1 rockets for L2 are extremely exciting and a lot of fun. L2 rockets don't have to be 20lb tanks with 54mm mounts.

 

[Handeman]

Just my opinion, but I would fix your LOC IV and fly it on L1 motors as it was designed for. If you do add thicker fins and do L2, you are still stuck with small J motors as the only L2 motors you can stick it that 38mm hole.

I would suggest you build a rocket just for L2. Something 4" diameter, about 7-12 lbs with at least a 54mm MMT. That way you can fly most of the L2 range of motors (J - small L) and not go to extreme altitudes. You should be able to fly the largest motor for it and stay under your fields waiver, or at least not too much over.

 

[jd2cylman]

I will echo what some others have said here, and suggest you go with a 54mm MMT. A wide range of L2 motors in 54mm and you can always adapt down for 38mm. A lot tougher to adapt up. I've been in your place years ago. I thought, "I'll never fly any 54mm motors. I'll just build this with a 38mm mmt and be happy here." That lasts a year or two at best, then you'll be thinking, man I wish I could use a J450DM DMS... (AND YOU SHOULD... awesome motor!). So, you'll end up building another rocket with a 54mm mmt. Then you'll find out that 75mm 2 grain motors are cheaper than 54mm 6XL motors and think, man I shoulda gone with a 75mm mmt. Then you're building another rocket...

Wait. What were we discussing??? I might have gone off track here with some sort of flashback...
I'm tryin ta save you money, yeah, that's it, yeah...

 

[DaveW6DPS]

Then you're building another rocket...

Are you implying that building more rockets is a bad thing? A cursory count in my shed indicates that I have built dozens over the years...

In my opinion, (yes, grumpy old man mode is on) there are two very dangerous and unfortunate trends creeping into the hobby in the last few years.

First, the idea that you have to start out at level 2. I see people whose plan is to build one rocket for both their level 1 and level 2 cert. So they have built one high power rocket in their life, flown it twice, and they are now level 2 even though they don't have a clue about actual level 2 rockets and techniques.

Second, the idea of one "swiss army rocket" that does everything encourages flights that are over, or under, powered. Over powering a mid-power rocket for a level 2 attempt is simply not a good idea, anecdotal instances of success notwithstanding. Pushing a rocket to the point that it shreds fins is dangerous. Thicker fins and layer of glass are not the right answer.

 

[jd2cylman]

Are you implying that building more rockets is a bad thing? A cursory count in my shed indicates that I have built dozens over the years...

In my opinion, (yes, grumpy old man mode is on) there are two very dangerous and unfortunate trends creeping into the hobby in the last few years.

First, the idea that you have to start out at level 2. I see people whose plan is to build one rocket for both their level 1 and level 2 cert. So they have built one high power rocket in their life, flown it twice, and they are now level 2 even though they don't have a clue about actual level 2 rockets and techniques.

Second, the idea of one "swiss army rocket" that does everything encourages flights that are over, or under, powered. Over powering a mid-power rocket for a level 2 attempt is simply not a good idea, anecdotal instances of success notwithstanding. Pushing a rocket to the point that it shreds fins is dangerous. Thicker fins and layer of glass are not the right answer.

No, not actually. But, the OP originally stated he wanted to keep costs down. Therefore building one rocket with a 54mm hole allows him to fly a wider range of high end 38's up to mid 54's. But it's just a suggestion, and he may either listen to it or chuck it.

 

[3stoogesrocketry]

Are you implying that building more rockets is a bad thing? A cursory count in my shed indicates that I have built dozens over the years...

In my opinion, (yes, grumpy old man mode is on) there are two very dangerous and unfortunate trends creeping into the hobby in the last few years.

First, the idea that you have to start out at level 2. I see people whose plan is to build one rocket for both their level 1 and level 2 cert. So they have built one high power rocket in their life, flown it twice, and they are now level 2 even though they don't have a clue about actual level 2 rockets and techniques.

Second, the idea of one "swiss army rocket" that does everything encourages flights that are over, or under, powered. Over powering a mid-power rocket for a level 2 attempt is simply not a good idea, anecdotal instances of success notwithstanding. Pushing a rocket to the point that it shreds fins is dangerous. Thicker fins and layer of glass are not the right answer.

The trends that you speak of have been there since the mid 90's when I started flying. I have suggested in the past that there should be a required amount of flights per level before you can move on. By TRA laws you could build one rocket with motor eject for cert 1 and 2 . Then build a level 3 rocket and fly that , all without demonstrating any practical experience or real world experience with electronics . Pushing a rocket beyond its capacity is a learning experience. Have you ever shredded a rocket? There's a huge difference in constructing a rocket to handle any motor you can stick in it , vs constructing a rocket stock and thinking it *might* work . How do you know how much is too much or not enough if you don't try ?

 

[DaveW6DPS]

...There's a huge difference in constructing a rocket to handle any motor you can stick in it , vs constructing a rocket stock and thinking it *might* work . How do you know how much is too much or not enough if you don't try ?

One major clue is that the manufacturer says it is designed for a particular range of motors. If you understand how to beef up a rocket, and do so, then it may be safe to increase the total impulse. The problem is the when people say 'just put a J in it an let er rip'. A stock rocket designed for F, G, and H is not a rocket you should just put a J in, any more than you should try it on a B or C.

These trends have been around a while, but they seem to be getting worse. This is especially true with NAR, since one person can make their two flights and get level 2, then sign off other people to level 2. Although as you mentioned, TRA rules also allow for the one rocket-two flight scenario. Level 3 has better ways to verify competencies, since the L3CC or TAP need to see documentation.

 

[MikeyDSlagle]

Okay Mr grumpy old man from Barstow, you can quit tossing around my let er rip comment now. Turn off grumpy mode and let's not drag the thread into another discussion about the cert progress.

"Thicker fins and layer of glass are not the right answer."
Wrong
That often is the only difference between an L1 and L2 rocket. Had the OP's had 1/4" LOC fins or had a wrap of glass he likely would be L2 and we wouldn't be having this discussion. I didn't know I could have started at L2, odd I wasn't given the choice and had to start at L0.

Folks push the envelope quite regularly. I know of rockets that shred on motors that are comfortably in the suggested range. And others than can take much more than what a manufacturer suggests. And I saw one fly on I motors be destroyed by an H550. There is a bit more to it than saying a particular rocket will fly on any H or any G simply because it is in their "range". In this instance you may be right however, I wasn't aware that that particular rocket had 1/8" fins.

 

[DaveW6DPS]

Okay Mr grumpy old man from Barstow, you can quit tossing around my let er rip comment now. Turn off grumpy mode and let's not drag the thread into another discussion about the cert progress.

"Thicker fins and layer of glass are not the right answer."
Wrong
That often is the only difference between an L1 and L2 rocket. Had the OP's had 1/4" LOC fins or had a wrap of glass he likely would be L2 and we wouldn't be having this discussion. I didn't know I could have started at L2, odd I wasn't given the choice and had to start at L0.

Folks push the envelope quite regularly. I know of rockets that shred on motors that are comfortably in the suggested range. And others than can take much more than what a manufacturer suggests. And I saw one fly on I motors be destroyed by an H550. There is a bit more to it than saying a particular rocket will fly on any H or any G simply because it is in their "range". In this instance you may be right however, I wasn't aware that that particular rocket had 1/8" fins.

True that not all H motors are created equal. That is why there are so many different H motors. But a J is not an H.

1/4' fins can shred in transonic buffeting almost as easy as 1/8". It is a matter of design plan as much as material.

This is a discussion about certification, be cause this was someone attempting a cert they were not ready for with predictably poor results. But this will be my last post in this thread. I am sure there will be a similar one before long.

 

[rharshberger]

I watch a certain prototype for a recently re-released classic split fin design shred when the 1/8" ply fins failed on a K550, if those fins had been 1/4" it wouldn't have happened, and it probably would have been okay on a L1000. No glass would have been needed either and the 1/8" fins had flown earlier on a J iirc with no issues.

 

[Who_Cares]

Well this has gone on for a bit longer than I thought and raised some interesting arguments. However, I think it is important to clarify my original intent.

My original request was to ask a question about custom building a level 2 rocket. The answer to that question is to buy a kit because that is easier and I agree. But I wanted to save money by reusing some of my parts from my previous rocket. However, a couple people had some great suggestions on how to repair my LOC IV. Now here is where some more clarification is needed:
1. I knew I was pushing the limits of the rocket with a J270, but it was the last launch of the season and I thought it would be nice to try for level 2.
2. I never intended to fly my LOC IV regularly with level 2 motors. I simply wanted to get the cert than build a proper level 2 rocket.
3. From this thread I've realized I can have the best of both worlds, repair my LOC IV to fly on level 1 motors and build a proper level 2 kit for certification since I was planning on building one anyways. (I don't know why everyone assumed I wasn't going to build a legit level 2 kit, maybe it was the keeping the costs down statement, but really I said that because I didn't want all the money I used to build the LOC IV to go to waste.)

To respond to comments:

The trends that you speak of have been there since the mid 90's when I started flying. I have suggested in the past that there should be a required amount of flights per level before you can move on. By TRA laws you could build one rocket with motor eject for cert 1 and 2 . Then build a level 3 rocket and fly that , all without demonstrating any practical experience or real world experience with electronics . Pushing a rocket beyond its capacity is a learning experience. Have you ever shredded a rocket? There's a huge difference in constructing a rocket to handle any motor you can stick in it , vs constructing a rocket stock and thinking it *might* work . How do you know how much is too much or not enough if you don't try ?

I actually completely agree with this idea and would like to see TRA implement a rule where you have to do a certain number of flights at each level. I think the reason why so many people want to get to level 2 as quickly as possible is because a lot of people find the level 2 stuff a lot more fun than level 1. Level 2 opens up a lot of possibilities.

True that not all H motors are created equal. That is why there are so many different H motors. But a J is not an H.

1/4' fins can shred in transonic buffeting almost as easy as 1/8". It is a matter of design plan as much as material.

This is a discussion about certification, be cause this was someone attempting a cert they were not ready for with predictably poor results. But this will be my last post in this thread. I am sure there will be a similar one before long.

To reply broadly to the majority of your comments in this thread as respectively as possible.
You've made multiple assumptions in this thread based on very little information which I find troubling. First, you imply the person helping me with my level 2 checklist was not competent. He is in fact the opposite and he is a great mentor. Second, you also assumed because I shredded one rocket during my certification I automatically must not have been "ready."

This is a discussion about certification, be cause this was someone attempting a cert they were not ready for with predictably poor results. But this will be my last post in this thread. I am sure there will be a similar one before long.

This is not a discussion about certification and never was; you're the one trying to make it a discussion about certification.

And to be honest I have to ask what is wrong with the fact that I failed my level 2 cert before I was "ready?" It was done in a safe and controlled way, nobody was hurt, and I had fun doing it. What is wrong with that? I like to learn by doing, so I did, I failed, and I'm trying again. Isn't that the whole point of the hobby after all?

 

[blackjack2564]

And to be honest I have to ask what is wrong with the fact that I failed my level 2 cert before I was "ready?" It was done in a safe and controlled way, nobody was hurt, and I had fun doing it. What is wrong with that? I like to learn by doing, so I did, I failed, and I'm trying again. Isn't that the whole point of the hobby after all?

Nothing wrong. Nothing at all.
The bigger question is: What is your motivation/goal?
Just take a bit of time & do some research, I might suggest using Open Rocket to simulate some flights on what ever kit your looking at.
You can ask here for the file on any rocket and some are on websites where you buy them.
Look at the speed on various motors vs altitude by propellent types. You will be amazed at how much info you pick up, that may help in your choice..... paper, fiberglass,performance, price etc.

.....after all...it really IS rocket science!

 

[Who_Cares]

Nothing wrong. Nothing at all.
The bigger question is: What is your motivation/goal?
Just take a bit of time & do some research, I might suggest using Open Rocket to simulate some flights on what ever kit your looking at.
You can ask here for the file on any rocket and some are on websites where you buy them.
Look at the speed on various motors vs altitude by propellent types. You will be amazed at how much info you pick up, that may help in your choice..... paper, fiberglass,performance, price etc.

.....after all...it really IS rocket science!

My main goal is just trying to get as high as possible really. And I did simulate the flight on OpenRocket. The predicted max speed was mach 0.85 which is how I knew I was going to be pushing it with the J270W.

 

[dr wogz]

"Keep costs down" and "L2" don't really go well together!

It's like buying a Camaro, and re-using the wheels from the Toyota Echo..

We've also seen it a few times: Someone buys a kit, then proceeds to change just about everything in the kit.. I've seen it with rockets, R/C airplanes, and R/C cars. (although for cars its more of an "upgrade' than a swap-out)

Buy a Madcow Super DX-3 and do your L2 with that like many others have... the kit is probably the cost of your intended FG tube & fins..

 

[MikeyDSlagle]

"Keep costs down" and "L2" don't really go well together!

It's like buying a Camaro, and re-using the wheels from the Toyota Echo..

We've also seen it a few times: Someone buys a kit, then proceeds to change just about everything in the kit.. I've seen it with rockets, R/C airplanes, and R/C cars. (although for cars its more of an "upgrade' than a swap-out)

Buy a Madcow Super DX-3 and do your L2 with that like many others have... the kit is probably the cost of your intended FG tube & fins..

I work with a lady who drove a Toyota Camry. Well she goes and buys a Camaro with a V6! A V6! In a Camaro. She says she bought it for the "gas mileage". People do not buy Camaros because they are economy cars. About as bad as the guy, who is now assistant lead, who bought a jeep, customized it, lift kit, the whole package, so he "could run over things". Then trades it in on a Ford Mustang with a 4 cylinder. I didn't know they made such a thing. I work with some smart ones for sure.

So not to be totally off topic I must mention rockets. So, well I just did.

 

[DavidMcCann]

Just my opinion, but I would fix your LOC IV and fly it on L1 motors as it was designed for. If you do add thicker fins and do L2, you are still stuck with small J motors as the only L2 motors you can stick it that 38mm hole.

I would suggest you build a rocket just for L2. Something 4" diameter, about 7-12 lbs with at least a 54mm MMT. That way you can fly most of the L2 range of motors (J - small L) and not go to extreme altitudes. You should be able to fly the largest motor for it and stay under your fields waiver, or at least not too much over.

You say this every time someone says the word "L2", however it completely ignores the fact some people don't intend to fly larger L2 motors, and are likely stretching the budget to fly one or two small J's a year. Those people are well served by smaller rockets like this.

"cheaper to have one rocket that can do it all" only works if that person actually intends to be banging out big K's and L's. If they're never going to fly a $200 motor, why bother building for it? and if they do want to/ have the means to pop off $200 flights, at that point knocking out another kit isn't a big deal later on.

 

[grouch]

So much agree it's not funny. I have one single rocket with a 54mm and I will probably only fly it once on a 54mm DMS. Not every L2 flyer wants to fly a K or L. The LOC 4 with a reasonable 720 newtons will give you a L2 cert with a rocket light enough to fly on I's and larger H's all day long. Some people (me) prefers options at the lower end instead of the higher end of the band.

 

[Ez2cDave]

If you do add thicker fins and do L2, you are still stuck with small J motors as the only L2 motors you can stick it that 38mm hole.

Well, there is THIS motor, but you might have to "leave some hanging out the back end" . . .

R K627LR-5,7,11,14 Loki 38 x 1200 1518.691 688 TRA HPR

LOL !

Dave F.

 

[Flyfalcons]

Thicker fins and layer of glass are not the right answer.

Gotta disagree here. Practically speaking, the only real difference between the LOC-IV only handling up to H motors vs any other 4" cardboard 54mm L2-capable rocket is 1/8" vs 1/4" ply fins.