OpenRocket tutorials: request for topics

[neil_w]

Sometime fairly soon we'll be adding a "Tutorials" section to the openrocket.info website. These will be short(-ish) tutorials covering a well-defined area of program, much like the tutorial threads I have posted on this forum in the past (and those will migrate over to the new site).

What are some areas of the program that are unclear, or have tripped you up in the past, that would make for good tutorial topics? My aim is to make this the #1 help resource for OpenRocket problems.

 

[kjhambrick]

Neil --

I am not sure it warrants an entire tutorial but what is the best way to account for the mass of paint and stickers on a small rocket ?

Example: I finished building a BT-55 rocket recently and it weighed 199 grams before paint and stickers.

Then after painting and stickers it came in at 223 grams.

The paint covers the entire wetted surface of the model so it shoudn't have changed the CG and I don't like to add virtual internal 'Mass Components' unless there is no alternative.

Anyhow, is there a way to add the mass of 'finishing materials' to a rocket after it has been modeled ?

Thanks !

-- kjh

 

[neil_w]

Neil --

I am not sure it warrants an entire tutorial but what is the best way to account for the mass of paint and stickers on a small rocket ?

Example: I finished building a BT-55 rocket recently and it weighed 199 grams before paint and stickers.

Then after painting and stickers it came in at 223 grams.

The paint covers the entire wetted surface of the model so it shoudn't have changed the CG and I don't like to add virtual internal 'Mass Components' unless there is no alternative.

Anyhow, is there a way to add the mass of 'finishing materials' to a rocket after it has been modeled ?

Thanks !

-- kjh

This could be worth a short tutorial, I'll consider it.

There is no "standard" way to estimate the weight of paint in advance, since everyone's painting regimen is different. There are different approaches to handling this in OpenRocket, although both are pretty much the same as handling mass and CG in general.

If you want to try to estimate the paint weight in advance, then about all you can do right now is get an idea from your own builds about how much your paint weighs. From the above example we might conclude "10% of the dry weight of the rocket". And so, to incorporate that, you could put a mass object equal to 10% of the weight of the rest of the rocket and put it at the CG.

After the rocket is build, you want to do what you'd do anyway: weight the whole rocket and measure the CG, and then either
(a) apply overrides to match your measurements, or
(b) add a new mass object (or just edit the one you added above), setting its mass so that the reported mass will equal your measurements. Then adjust the position of the mass object so that the reported CG will equal your measurement.

 

[kjhambrick]

Thanks Neil !

Adding an internal mass object at the dry-mass CG to adjust the final mass is all I could come up with.

One attribute of a rocket that would be good to know is the wetted area of the rocket.

I imagine that the mass of the paint for each builder would scale pretty well with wetted area,

Then we would be on our own for sticker masses

Thanks again !

-- kjh

 

[neil_w]

One attribute of a rocket that would be good to know is the wetted area of the rocket.

I imagine that the mass of the paint for each builder would scale pretty well with wetted area,

Then we would be on our own for sticker masses

Yeah, wetted area might be useful, along with different settings for light/medium/heavy paint. However, that still leaves glue unaccounted for, so you'd still need measurement and override at the end of the build, so I don't know if it would be *that* useful.

 

[WFWalby]

Sometime fairly soon we'll be adding a "Tutorials" section to the openrocket.info website. These will be short(-ish) tutorials covering a well-defined area of program, much like the tutorial threads I have posted on this forum in the past (and those will migrate over to the new site).

What are some areas of the program that are unclear, or have tripped you up in the past, that would make for good tutorial topics? My aim is to make this the #1 help resource for OpenRocket problems.

Zero mass cone for base drag?

 

[neil_w]

Zero mass cone for base drag?

Yes, good one. Will do that one next.

 

[NTP2]

Rendering

 

[neil_w]

Rendering

Please clarify.

I am already planning to bring over my existing decals tutorial (https://www.rocketryforum.com/threa...so-quick-and-fairly-complete-tutorial.129192/), probably split into two or three since it's a *lot*.

 

[NTP2]

Please clarify.

The thing with the back ground like this
Credit @lakeroadster.

 

[neil_w]

The thing with the back ground like this View attachment 612191
Credit @lakeroadster.

Tools -> Photo Studio

 

[NTP2]

Tools -> Photo Studio

Yeah now put that somewhere in the tutorials (I had no idea that it was that easy)

 

[bobby_hamill]

Neil
Been having trouble with inserting a decal on the sides of fins in openrocket.
One fin worked perfect where the fin was black with a white lettering decal.And I used the "Sticker"
option The other 2 wins need to be White with black lettering . I can get the decal on the same side of the 2
white fins but when I try to insert the same decal on the opposite side of the 2 decals using sticker or clamp option
all I get is a black solid fin for that side you can see it in the 2 attachments below



Thanks for any help

Bobby

 

[neil_w]

Need an ORK file to help

 

[bobby_hamill]

Here is the ORK file and you can see the 2 white fins with lettering on the one side.
I know I can inset "phantom" set of fins to edit the other side, but the black fin accepted
the decal on both sides with no "phantom" sets

 

[neil_w]

(1) I don't see a decal file included for white, right side
(2) When I put the left side white decal on the right, it works fine
(3) what version of OR are you using?

 

[bobby_hamill]

using 22.02 version
here are the 2 images for the fins

 

[bobby_hamill]

Neil

Attached are all 4 images

 

[neil_w]

Unless I'm hallucinating, the two black images are the same, and the two white images are the same?