First high power build questions

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Go with OpenRocket (its free after all). There are things that Rocksim does that OR doesn't, but not for standard style rockets. And OR will import Rocksim rocket files anyways. If you have need later for the features from Rocksim you can always invest.

I have both, but primarily use OR.
 
I have read quite a bit about hpr, so I knew that speed off the rail was important. Also, basically every high power thread I've read mentions a Sim, so I knew that I better figure it out. I've been contemplating whether I should buy rocksim or not. I think I'll give open rocket a shot first and see how I do with that. Thanks for your help!

Sounds like a great idea - OpenRocket is a very capable program and a lot of people on TRF can help you out. Eventually, you may find Rocksim worth the cost, but OpenRocket should handle most of what you need.
 
And don't forget to also look at Thrustcurve.org. while not as detailed as RS or OR, it will spit out a list of capable motors for the given dimeter & weight & inputted (guessed?) Cd (drag).

You can then take the outputted data, and make yourself a really nice motor / delay / altitude / speed table in Excel..

https://www.thrustcurve.org/
 
Thanks for all the help! I downloaded and installed OR last night. Hopefully I’ll have time to tinker with it when I get home from work tonight.
 
double check the default values as you build your rocket
Overrride them as needed..

Also, make sure your parachute is set to open when it actually opens. I usually change mine to open at Apogee, review the delay it calculates, and work from there, rather than plugging in multiple motor delays to get a result I like.
 
I've been trying to place an order with Loc/Precision and haven't been able to get a hold of them. I've tried phone and email.
Anybody had contact with them or know what's up? Thanks!
 
Figured I should attach a sample of my 'flight sheet' I described above.

I started with the .CVS file from Thruscurve.org, then massaged the columns & added a few formulas..

I have one for each HPR rocket I have, and for each motor diameter [so I can use adapters; 29mm in a 38mm rocket..]

Choosing a motor & filling out the flight card is now super easy!
 

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Figured I should attach a sample of my 'flight sheet' I described above.

I started with the .CVS file from Thruscurve.org, then massaged the columns & added a few formulas..

I have one for each HPR rocket I have, and for each motor diameter [so I can use adapters; 29mm in a 38mm rocket..]

Choosing a motor & filling out the flight card is now super easy!

This is a great idea - I do the same for my rockets.

Pro-tip - once you have all the work done, upload them as sheets in one workbook on Google Sheets. Then you have them all in one place and can access them easily on a tablet, phone, etc, even when you have no cell coverage at the launch site. I set my iPad up on my launch prep table and have all the info at my fingertips. Add in some cells/rows to put in your black powder charge measurements, suitable parachute sizes, etc and you have everything you need at the launch.

In the same workbook, I also have sheets that hold useful reference info - pressure port hole sizing, piston charge recommendations, typical eject charges in commercial motors, recommended launch speeds for different conditions, etc.

You can find all that info on the web, but at a launch, it is not only easier to have it all in one place, it is nice to have it on my device and be able to access it with no data connection since getting a cell signal at many launch sites is like finding gold nuggets on the ground.
 
You compare the results with a OR or Rocksim results? Drag, etc. isn't taken into account by thrustcurve

Figured I should attach a sample of my 'flight sheet' I described above.

I started with the .CVS file from Thruscurve.org, then massaged the columns & added a few formulas..

I have one for each HPR rocket I have, and for each motor diameter [so I can use adapters; 29mm in a 38mm rocket..]

Choosing a motor & filling out the flight card is now super easy!
 
You compare the results with a OR or Rocksim results? Drag, etc. isn't taken into account by thrustcurve

No. But I should. It does include the Cd number. It also askes for weight & Dia. It's assumed the CP & CG are correct.. (do that in RS or OR)

Thrustcurve is a quick & easy method / place to determine the right / wrong motor for our given rocket. I found the data to be more than complete for what I wanted / needed. And, it's quick.. A list of all motors, all motors that pass, all motors that fail. Playing with the Cd number, gets pretty accurate results.

And, either in a binder5 or on your tablet / phone, you can approach a Vendor and ask: "do you have ______? No? OK, what about _____? Or ______?.." and make an educated choice (not a guess)
 
Has anyone experienced these “bubbles” before, and should I be concerned about the tube integrity in these places?

If they are anything like the Zephyr tubes that I got it should only be cosmetic. The tubes came with NUMEROUS bubbles and lifting of the top layer. I resorted to slicing open the largest of the bubbles and wicking some thin CA into them to seal them. The factory cut edges of the tubes all had layer separation issues too so I wicked some CA and later sanded them smooth. If it wasn't for the fact I was in a different country and the shipping costs were prohibitive I would have returned the kit for a replacement. It was probably a one off from the supplier that QC missed but jeepers was that an ugly looking tube.
 
Okay, so the rocket is just about complete, I just need to put the chute in and add nose weight. There's just one issue I have a couple more questions about. So I simmed the model in open rocket, and I can't seem to get the CG on the Sim to land exactly where it is on the rocket. Seems like my CG is slightly to the aft of where the Sim shows it. When I try to manually adjust the CG in the Sim, it makes it so that I can't really figure out how much nose weight to add, because the CG measurement is locked in if I override it. So, my idea is this, the CP on the Sim should be fairly accurate, so to get the stability to 1 caliber, I just need to add nose weight until the CG falls 1 body tube width ahead of the CP.... Is that correct? Also, is 1 caliber the stability I should be shooting for? I've read that in a few posts, and just wanted to double check. I'm attaching some photos of the (mostly) finished product. I think Mark over at stickershock23 did an incredible job in helping me out with the custom decals that are closer to scale. I'm pretty darn pleased with how it came out. There are a few spots that I touched up with the wrong color gray, I have some of the right color coming in the mail, and I'll just dab some of that over the spots I touched up with the wrong color. Thanks for everyone's help!
 

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Okay, so the rocket is just about complete, I just need to put the chute in and add nose weight. There's just one issue I have a couple more questions about. So I simmed the model in open rocket, and I can't seem to get the CG on the Sim to land exactly where it is on the rocket. Seems like my CG is slightly to the aft of where the Sim shows it. When I try to manually adjust the CG in the Sim, it makes it so that I can't really figure out how much nose weight to add, because the CG measurement is locked in if I override it. So, my idea is this, the CP on the Sim should be fairly accurate, so to get the stability to 1 caliber, I just need to add nose weight until the CG falls 1 body tube width ahead of the CP.... Is that correct? Also, is 1 caliber the stability I should be shooting for? I've read that in a few posts, and just wanted to double check. I'm attaching some photos of the (mostly) finished product. I think Mark over at stickershock23 did an incredible job in helping me out with the custom decals that are closer to scale. I'm pretty darn pleased with how it came out. There are a few spots that I touched up with the wrong color gray, I have some of the right color coming in the mail, and I'll just dab some of that over the spots I touched up with the wrong color. Thanks for everyone's help!

There's a couple of ways to manage the OR question. I would probably do the following:
Pack everything but the nose cone into the fin can.
Weigh, determine CG for the fin can, enter that as a mass and CG override for the body tube plus all subcomponents
Weight, determine CG for the nose cone, enter the mass and CG override for the nose cone but do not check the "override subcomponents" box.
Add the ballast as a mass object subcomponent under the nose cone.

That should let you adjust the ballast weight without messing with anything else. If this is a "one and done" nose weight operation, I would add enough to get to 1.2 calibers on the largest motor that you might want to fly it on. That gives you some margin for future growth. After determining that mass, check it again on the L1 motor you want to fly on to make sure you haven't gone overweight. You might need to make it a happy medium between the two. If the nose weight is adjustable, then add enough to get to 1.2 to 1.5 calibers on the motor you plan to fly. Do check the speed off the rail again.
 
There's a couple of ways to manage the OR question. I would probably do the following:
Pack everything but the nose cone into the fin can.
Weigh, determine CG for the fin can, enter that as a mass and CG override for the body tube plus all subcomponents
Weight, determine CG for the nose cone, enter the mass and CG override for the nose cone but do not check the "override subcomponents" box.
Add the ballast as a mass object subcomponent under the nose cone.

That should let you adjust the ballast weight without messing with anything else. If this is a "one and done" nose weight operation, I would add enough to get to 1.2 calibers on the largest motor that you might want to fly it on. That gives you some margin for future growth. After determining that mass, check it again on the L1 motor you want to fly on to make sure you haven't gone overweight. You might need to make it a happy medium between the two. If the nose weight is adjustable, then add enough to get to 1.2 to 1.5 calibers on the motor you plan to fly. Do check the speed off the rail again.
Excellent! It is the LOC removable nose weight system, so I can make different weight cartridges to put in there. Excellent information on how to work around the open rocket issues. I'll give that a shot. Thanks!
 
Okay, so the rocket is just about complete, I just need to put the chute in and add nose weight. There's just one issue I have a couple more questions about. So I simmed the model in open rocket, and I can't seem to get the CG on the Sim to land exactly where it is on the rocket. Seems like my CG is slightly to the aft of where the Sim shows it. When I try to manually adjust the CG in the Sim, it makes it so that I can't really figure out how much nose weight to add, because the CG measurement is locked in if I override it. So, my idea is this, the CP on the Sim should be fairly accurate, so to get the stability to 1 caliber, I just need to add nose weight until the CG falls 1 body tube width ahead of the CP.... Is that correct? Also, is 1 caliber the stability I should be shooting for? I've read that in a few posts, and just wanted to double check. I'm attaching some photos of the (mostly) finished product. I think Mark over at stickershock23 did an incredible job in helping me out with the custom decals that are closer to scale. I'm pretty darn pleased with how it came out. There are a few spots that I touched up with the wrong color gray, I have some of the right color coming in the mail, and I'll just dab some of that over the spots I touched up with the wrong color. Thanks for everyone's help!
What I do is add another stage that just contains the noseweight, and override the mass and CG for the rest of the rocket.
 
I’m considering buying rock sim… it it any easier to work with than open rocket?is is worth the money? Any insight on this would be greatly appreciated as well
 
I’m considering buying rock sim… it it any easier to work with than open rocket?is is worth the money? Any insight on this would be greatly appreciated as well
For my own purposes, OR does everything I need, and is easier and more reliable with regard to appearances (colors, decals, etc.) Rocksim has some features that OR lacks, which may or may not be important to you.

But no need to take anyone else's word for it; try out the free Rocksim trial and decide for yourself.
 
For my own purposes, OR does everything I need, and is easier and more reliable with regard to appearances (colors, decals, etc.) Rocksim has some features that OR lacks, which may or may not be important to you.

But no need to take anyone else's word for it; try out the free Rocksim trial and decide for yourself.

That’s a very good point. I forgot about the free trial. I was too busy balking at the price of the software beyond the free trial. Thanks!
 
I purchased RS years ago and have always been happy with the money spent on it. Personally I never bothered with OR as it was a bit simplistic when I needed a simulator. Its capabilities have improved over the years but I have never bothered with it.
 
I think I got open rocket to work using boatgeek’s method. I really appreciate the help! I’m pretty confident the sim looks good, but I suck at computer stuff, so I just want to make sure. I set the nose weight subcomponent at 400g, and I did a CG override on the inner tube I’m using for the nose weight so it’s at about where I’m guessing the CG will fall once I add the lead and epoxy to the weight cartridge. For simulation purposes I chose a Cesaroni H225-14A just by picking something close to what I thought would work well. Stability is 1.36 cal, speed off the rail is 56.7 fps, and apogee is 1178 ft on the simulation I just ran. I’m going to attach a screenshot of the sim just so you guys can tell me if something looks wrong. My next question is this: is the H225 a good choice of motor? Speed off the rail seems good in the sim going by what I’ve read, and apogee is still pretty low. Just wondering if any of y'all had any suggestions on the motor, and if the sim looks right. Thanks!
Edit: attached the wrong screenshot
There's a couple of ways to manage the OR question. I would probably do the following:
Pack everything but the nose cone into the fin can.
Weigh, determine CG for the fin can, enter that as a mass and CG override for the body tube plus all subcomponents
Weight, determine CG for the nose cone, enter the mass and CG override for the nose cone but do not check the "override subcomponents" box.
Add the ballast as a mass object subcomponent under the nose cone.

That should let you adjust the ballast weight without messing with anything else. If this is a "one and done" nose weight operation, I would add enough to get to 1.2 calibers on the largest motor that you might want to fly it on. That gives you some margin for future growth. After determining that mass, check it again on the L1 motor you want to fly on to make sure you haven't gone overweight. You might need to make it a happy medium between the two. If the nose weight is adjustable, then add enough to get to 1.2 to 1.5 calibers on the motor you plan to fly. Do check the speed off the rail again.
931332AE-4BB3-4411-ADF2-1706D722DE04.jpeg350C7342-16C2-4944-81E1-0D3C086B44FB.jpeg
 
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