LOC Precision 4 inch AIM-54C Phoenix

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RobertC

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I already have another thread about this rocket build, but the title of the thread doesn't mention what the rocket is. I'm going to attach my open rocket file to this thread so other people can use it in the future, in the file I included a 38mm motor adapter, but that should be pretty easy to remove if anyone decides to use the file. I thought it might be easier for them to find it if I put the manufacturer and model info in the title, so that's my main reason for making a new thread. Also I'm not sure anyone saw my last post on that thread because I haven't seen any replies, and y'all are usually pretty quick to help when I post over there. I asked on my previous thread if y'all thought the file looked right in case I missed a critical detail of some sort, but for some reason I didn't think about attaching the whole file and I only included a screenshot, so I'm going to include the file this time. I apologize if I'm asking dumb questions, I'm just not the greatest with computers. This is my first time using open rocket, and as near as I can tell, the simulation looks good, but was hoping someone with more experience than me wouldn't mind taking a look at it just to see if I did something dumb and have something set wrong or something. For my last simulation, I picked a Cesaroni H225-14A for the motor. On that simulation I added 400g of nose weight. Stability is 1.36 cal, speed off the rail is 56.7 fps, and apogee is around 1200 ft. I'm just curious if these are good numbers for a certification flight? I'm also curious if I should be concerned about drag separation? I'm also going to include my photos again, just in case the unthinkable happens. then at least there's photos of it floating around. Thanks for everyone's help!
 

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Sandy H.

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I can't comment on that rocket's stability, but I can comment on the build - AWESOME!!! Great looking rocket. Well done.

If it is a LOC rocket built close to specs and flying on motors they spec'd, I'd say you are fine. My experience with OpenRocket is minimal but not zero. It is a good tool for typical rockets, but the Phoenix has a lot of forward fin area and I have not modelled things like that before. LOC knows the CP and you can measure the CG. If you don't get good info from the forum, I would say a quick phone call to LOC would give you the confidence you need or give you a direction for update.

Either way, as I said before, great looking rocket!!!

Sandy.
 

RobertC

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I can't comment on that rocket's stability, but I can comment on the build - AWESOME!!! Great looking rocket. Well done.

If it is a LOC rocket built close to specs and flying on motors they spec'd, I'd say you are fine. My experience with OpenRocket is minimal but not zero. It is a good tool for typical rockets, but the Phoenix has a lot of forward fin area and I have not modelled things like that before. LOC knows the CP and you can measure the CG. If you don't get good info from the forum, I would say a quick phone call to LOC would give you the confidence you need or give you a direction for update.

Either way, as I said before, great looking rocket!!!

Sandy.
Thank You! That's a great point you brought up about using LOC's CP info. I'm really glad you mentioned that! It seems the CP on the Sim is about 2" further to the rear from what LOC listed. I added the fairings at the base of the front fins on my own to try to make it look more scale. On the Sim, I just increased the fillet size to about what the size of those fairings are, I wonder if that changed something, or there's also the fact that I couldn't get the nose cone shape completely right on the Sim, so maybe that's what changed it too. Other than that, all the dimensions were measured right off the rocket to make the Sim, so I'm guessing it's one or a combination of those two things. LOC has the CP at 27" (+/- .5"). The Sim has it at 29 11/64". I wonder if I should add more nose weight.
 

David Schwantz

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I used same rocket for L1 cert.
AT H283ST. Built stock, LOC CP & CG measurements. Now I fly her with J250W and takes a lot more lead up front. Just add lead till you get to LOC's CG. Mine flies great at that. Just be aware all that fin can weather vane on you. Good luck, nice bird you got there. PS, did you use LOC RNWS?
 

RobertC

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I used same rocket for L1 cert.
AT H283ST. Built stock, LOC CP & CG measurements. Now I fly her with J250W and takes a lot more lead up front. Just add lead till you get to LOC's CG. Mine flies great at that. Just be aware all that fin can weather vane on you. Good luck, nice bird you got there. PS, did you use LOC RNWS?
I was just thinking that I should probably use LOC's CP too. Better to be nose heavy than tail heavy. I thought about weather vaning as well. If the wind is too high at the next launch I'm going to wait for another launch. I did use the RNWS. Quite a clever feature in my opinion.
 

kuririn

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You can check your OR file against the Rocsim file on the LOC website.
OR can read .rkt files.
Nice build. Let us know how she flies.
Videos or it didn't happen.
 

RobertC

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You can check your OR file against the Rocsim file on the LOC website.
OR can read .rkt files.
Nice build. Let us know how she flies.
Videos or it didn't happen.
I did not know that! That is a massively helpful little bit of information right there. I will definitely try to get video.
 

RobertC

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Also, just wanted to bring up nose cone fit again. If I flip the rocket upside down, the nose cone stays all the way in with no movement at all, then if I wiggle the rocket, the nose cone starts to move, but it takes quite a bit of wiggling to get it to come all the way off. Does this sound right? Should I sand more off till it's only a little wiggling to get it to fall out? It takes quite a bit more wiggling to get it to fall out in comparison to all my mid power rockets, but the fit feels different in comparison to my other rockets as well. I'm comparing it mostly to my Aerotech Strong Arm, but that has a smooth shoulder on the nose cone. This rocket has two raised rings around the shoulder that seem to be grabbing the body tube a bit more. I don't want to take too much material off of those rings and end up with a drag separation issue, but at the same time, I definitely don't want a failed parachute deployment. Once again, all the help y'all have provided is very much appreciated
 

JasonB

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I was told by someone with more experience than myself that you should be able to invert the rocket, shake it, and the nose cone should only move 1/2in or so…
 

JasonB

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I dont get to wrapped up on the sims… i weigh the rocket loaded, i measure the CG with a string (trying to keep the laundry to the rear as if it was vertical) and compare it to
the CP … go or nogo. Then i make sure the mass, cg, and cp are close as I can in the sim and run it. Dont care what parts are in the rocket as long as those other parameters are met for the simulation.

Then get the delay for motor separation and use it.
 

David Schwantz

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Instead of sanding the NC, I take an exacto blade and scrape the 2 little rings around the shoulder to get the fit that I want.
 

QFactor

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I already have another thread about this rocket build, but the title of the thread doesn't mention what the rocket is. I'm going to attach my open rocket file to this thread so other people can use it in the future, in the file I included a 38mm motor adapter, but that should be pretty easy to remove if anyone decides to use the file. I thought it might be easier for them to find it if I put the manufacturer and model info in the title, so that's my main reason for making a new thread. Also I'm not sure anyone saw my last post on that thread because I haven't seen any replies, and y'all are usually pretty quick to help when I post over there. I asked on my previous thread if y'all thought the file looked right in case I missed a critical detail of some sort, but for some reason I didn't think about attaching the whole file and I only included a screenshot, so I'm going to include the file this time. I apologize if I'm asking dumb questions, I'm just not the greatest with computers. This is my first time using open rocket, and as near as I can tell, the simulation looks good, but was hoping someone with more experience than me wouldn't mind taking a look at it just to see if I did something dumb and have something set wrong or something. For my last simulation, I picked a Cesaroni H225-14A for the motor. On that simulation I added 400g of nose weight. Stability is 1.36 cal, speed off the rail is 56.7 fps, and apogee is around 1200 ft. I'm just curious if these are good numbers for a certification flight? I'm also curious if I should be concerned about drag separation? I'm also going to include my photos again, just in case the unthinkable happens. then at least there's photos of it floating around. Thanks for everyone's help!
I have the identical rocket, but it's the Madcow kit. Your build, weights and CP are are nearly identical to mine. I have flown the Phoenix on a host of motors - but nothing down around the H225 impulse. It passes muster in my Rocksim simulations. I get 60 fps on an 8 ft. rail, but I find the Phoenix is a bit wobbly when it first comes off the rail with motors that have a low initial thrust, and then it straightens up. I found the AeroTech H550 motor (reload and DMS) hits the sweet spot for this rocket with a solid launch and an apogee at around 1400 ft.

So you may want to look at a motor that has just a little more punch in that first split second (tenth of a second?), or look to use a 10 ft. rail.
 

mo2872

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I used the same rocket for L1 cert last summer. Flew great on an AT H242T to about 900'. Also used around 400g in the RNWS. Your nosecone fitment sounds very similar to mine, as well. I can shake it by the cone, and it only slips around 1/2", but blows off with the ejection easily(or appears to from the ground!).
 

RobertC

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I used the same rocket for L1 cert last summer. Flew great on an AT H242T to about 900'. Also used around 400g in the RNWS. Your nosecone fitment sounds very similar to mine, as well. I can shake it by the cone, and it only slips around 1/2", but blows off with the ejection easily(or appears to from the ground!).
Awesome. Sounds like the fit of yours is about what mine is. I've simmed the H242T as well and thought that was what I'd choose for a while. I think I went up to the 225 to get more speed off the rail, It seemed to get moving a bit quicker. Awesome to hear from other people who have had successful cert flights on the same bird!
 

bobbyg23

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I was just thinking that I should probably use LOC's CP too. Better to be nose heavy than tail heavy. I thought about weather vaning as well. If the wind is too high at the next launch I'm going to wait for another launch. I did use the RNWS. Quite a clever feature in my opinion.
Here is mine at our last launch. Very windy and zero weather veining issued.https://youtu.be/BjelDCVSptI
 

Grog6

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I accidently launched a Bullpup D estes kit into a thunderstorm once;Someone found it in NC, several hundred miles away.
I always include my name address and email on rockets.
 

RobertC

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Here is mine at our last launch. Very windy and zero weather veining issued.https://youtu.be/BjelDCVSptI
Wow! Nice video! Great job with the filming. I'm really surprised that wind like that didn't have more of an effect on the flight, nice straight boost from what I see though.
 

hball55

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I already have another thread about this rocket build, but the title of the thread doesn't mention what the rocket is. I'm going to attach my open rocket file to this thread so other people can use it in the future, in the file I included a 38mm motor adapter, but that should be pretty easy to remove if anyone decides to use the file. I thought it might be easier for them to find it if I put the manufacturer and model info in the title, so that's my main reason for making a new thread. Also I'm not sure anyone saw my last post on that thread because I haven't seen any replies, and y'all are usually pretty quick to help when I post over there. I asked on my previous thread if y'all thought the file looked right in case I missed a critical detail of some sort, but for some reason I didn't think about attaching the whole file and I only included a screenshot, so I'm going to include the file this time. I apologize if I'm asking dumb questions, I'm just not the greatest with computers. This is my first time using open rocket, and as near as I can tell, the simulation looks good, but was hoping someone with more experience than me wouldn't mind taking a look at it just to see if I did something dumb and have something set wrong or something. For my last simulation, I picked a Cesaroni H225-14A for the motor. On that simulation I added 400g of nose weight. Stability is 1.36 cal, speed off the rail is 56.7 fps, and apogee is around 1200 ft. I'm just curious if these are good numbers for a certification flight? I'm also curious if I should be concerned about drag separation? I'm also going to include my photos again, just in case the unthinkable happens. then at least there's photos of it floating around. Thanks for everyone's help!
Nothing wrong with the stability, heck, you could be at a lot lower and be ok. I have rockets that have had .50 stability that fly perfectly. Speed off the rail, anything above 30 fps in fine too. 56.7 will certainly get you an arrow straight launch.
 

Pariah Zero

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I’m very late to the party, but… I certed 1&2 with my 4” LOC Phoenix. I’ll gladly tell you everything I think I know, provide my OpenRocket files, etc.

I have one suggestion from my own experience: use an “I” motor. The “H” I did my first attempt on had one major problem: there wasn’t enough altitude for the recovery system to do its job.

This is a different launch today at LDRS 39a: J250W-14A motor.

You’ll note the announcer mentions the rocket is named THUD. There’s a reason.

I’ll add the delay problem was because the universal delay drill I got from Aerotech was before AT added a calibration jig.

I thought I had drilled out 8 seconds. I had actually drilled out maybe one or two. It was the very weekend THUD got its name that AT’s problem was announced.
 
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RobertC

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I’m very late to the party, but… I certed 1&2 with my 4” LOC Phoenix. I’ll gladly tell you everything I think I know, provide my OpenRocket files, etc.

I have one suggestion from my own experience: use an “I” motor. The “H” I did my first attempt on had one major problem: there wasn’t enough altitude for the recovery system to do its job.

This is a different launch today at LDRS 39a: J250W-14A motor.

You’ll note the announcer mentions the rocket is named THUD. There’s a reason.

I’ll add the delay problem was because the universal delay drill I got from Aerotech was before AT added a calibration jig.

I thought I had drilled out 8 seconds. I had actually drilled out maybe one or two. It was the very weekend THUD got its name that AT’s problem was announced.
For some reason I never got an email about this post. I thought about jumping up to an I because of the lower altitude apogees the Sim shows on an H. I figured 1200 ft on the H225 was alright, but I suppose that is still a bit low. I think I will look into the I motor now that you mention it.
 

Pariah Zero

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For some reason I never got an email about this post. I thought about jumping up to an I because of the lower altitude apogees the Sim shows on an H. I figured 1200 ft on the H225 was alright, but I suppose that is still a bit low. I think I will look into the I motor now that you mention it.
It’s worth noting that I built mine “heavy” to survive my 5-year old son — as well as survive potential L1 Cert failures. (And I didn’t expect that failure to come from the Aerotech delay drill, of all things).

I ‘glassed the tube and fins with S-Glass, and filled all of the fin can voids with low density two part foam. Then made it perfectly smooth with body filler.

That required a corresponding increase in nose weight. All told, it raised my weight to 9 lbs for my L1 cert, and 10 lbs for L2.

An I-205W pushed it up to 272 m @ Black Rock.

A J250W pushed it to 748 m @ Black Rock and 749.5 m @ Bonneville.

I need to sand & finish the rocket.
 
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