OpenRocket... What A Difference A Decal Makes...

[K'Tesh]

I was working on the Estes Pro Series II Partizon (9702)'s .ork file today... Removing the "air" fins, and internal body tubes used to simulate the decals, when I noticed a dramatic change...

Here's the image grab from the old version...



And the new...



WOW!!! That's a 230 foot difference!
Just thought of something... The current motor is simmed with a G80-7. I overwrote the old sim, but I didn't mess with the motor when I did. So, I think the change is real. The mass seems to have changed (19.3oz ~ 1.21lb) too.

 

[noffie79]

I notice the older version has launch lugs. Does the new version? Not having those could possibly account for some of the difference...?

 

[neil_w]

This is why it would be very helpful to mark any part as "include in simulation" or not. Then you wouldn't have to worry about your phantom tunes Abe such.

 

[K'Tesh]

I notice the older version has launch lugs. Does the new version? Not having those could possibly account for some of the difference...?

The new version has launch lugs too, I just didn't rotate the rocket so that they were visible.

After posting that picture, I found that I failed to round the fin's edges... I saved the results, and had had to restart my computer.

I'm now getting a projected altitude of 2221 feet and a mass of 1.05lbs. A difference of 412' compared to the original.

 

[vance2loud]

Interesting to note the difference in stability margin as well

 

[dhkaiser]

One version has 3 fins the other 4?

 

[K'Tesh]

One version has 3 fins the other 4?

Well... kinda.

My old way of doing decals on fins was to create a fin in the shape of the decal, since I didn't know how to do them, and couldn't figure them out...

Then neil_w did his tutorial on decals, and I started adding them in. When I got the Part Of Zon from dhbarr (made even smaller by USPS/China Post), I decided to rework the Partizon file. The additional "air fins" were deleted and the decals were put in.

I had said from the beginning my .ork files were not to be trusted for their flight characteristics, however, they are rapidly approaching trustworthyness for simming both flight and appearance... If I could only get the Kevin and the gang to allow things to be turned off (air fin's drag, engine hook (fins) drag, and radially offset (eliminating the phantom body tubes).

 

[K'Tesh]

Ok... Re-did the first 4 PSII builder kits...

Projected altitude changes:

Argent went from 1989' to 2173' (Up almost 200')
Leviathan went from 697' to 447' (NEGATIVE by 250')
Stretch Leviathan from 548' to 1206' (More than DOUBLE!)
Partizon went from 1809' to 2221' (over 400')
Ventris from 1509' to 2509' (1000' increase)
​

The main change with the Ventris, was the elimination of the phantom body tube and LL in favor of externalized (and not counted for aerodynamic effect) Internal tubes.

Old...


New...


The Stretch Leviathan got simplified rail buttons, and the decals applied.
Most everything else was the elimination of the "air fins" and the "paint/decal" bands that were simmed with Internal tubes.

 

[Cabernut]

Mine weighs in at 18oz dry with the usual additions: rail buttons, kevlar leader, quick links etc. So it seems to be getting the weight right. Sims should be pretty close.