First high power build questions

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thzero

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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.
 

mtnmanak

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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.
 

dr wogz

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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..

 

RobertC

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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.
 

Donnager

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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.
 

Gemini Junkie

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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!
 

dr wogz

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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!
 

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mtnmanak

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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.
 

thzero

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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!
 

dr wogz

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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)
 

Rory Gin

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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.
 
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