Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > RockSim Asylum
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 01-18-2019, 04:44 PM
JumpJet's Avatar
JumpJet JumpJet is offline
Master Modeler
 
Join Date: Apr 2008
Location: Pueblo Colorado
Posts: 1,266
Default Cluster Model in Rocksim ?

How does one create a 2 engine cluster model using Rocksim? I don't see any options in the centering rings. Do you use a Pod to do this? Also is it possible to can't the engine tube a couple degrees. If not I'd still like to model a cluster model. I plan on test flying the model tomorrow but I would still like to modify it so I can use two of the correct engines.




John Boren
Reply With Quote
  #2  
Old 01-18-2019, 06:58 PM
tlainhart tlainhart is offline
Junior Rocketeer
 
Join Date: Mar 2018
Posts: 6
Default

Years ago I built a TLP Exocet MM-40, which flys on 2 24mm motors. I thought that I created a rocksim file, but perhaps not. I did find this on rocketreviews. While the graphic doesn't appear to list a two-motor cluster, the BOM does.
Reply With Quote
  #3  
Old 01-18-2019, 09:36 PM
rocketguy101's Avatar
rocketguy101 rocketguy101 is offline
frustrated aero
 
Join Date: Sep 2006
Location: Duncan, OK
Posts: 733
Default

When you have your body tube, add an "inner tube" and select motor mount [1]. Then in the design tree, select "Cluster"[2], then next. I picked the two engine option, then you can rotate the tubes horizontal (default) or other orientation. I don't see an option to cant the motors (a la Titan?) but you can change the radial position of each motor tube to space them farther apart.
Attached Thumbnails
Click image for larger version

Name:  RockSimCluster-1.jpg
Views: 31
Size:  181.4 KB  Click image for larger version

Name:  RockSimCluster-2.jpg
Views: 27
Size:  175.2 KB  Click image for larger version

Name:  RockSimCluster-3.jpg
Views: 24
Size:  182.4 KB  Click image for larger version

Name:  RockSimCluster-4.jpg
Views: 25
Size:  174.6 KB  Click image for larger version

Name:  RockSimCluster-5.jpg
Views: 23
Size:  220.3 KB  Click image for larger version

Name:  RockSimCluster-6.jpg
Views: 23
Size:  177.2 KB  Click image for larger version

Name:  RockSimCluster-7.jpg
Views: 25
Size:  177.6 KB  
__________________
David Stribling
NAR 18402 SR
But it is rocket science!
Get yer Barrowmans here
Reply With Quote
  #4  
Old 01-18-2019, 09:41 PM
rocketguy101's Avatar
rocketguy101 rocketguy101 is offline
frustrated aero
 
Join Date: Sep 2006
Location: Duncan, OK
Posts: 733
Default

OH...I fully understand your question now...how to create the centering ring for said cluster DOH! Hmm...I'm not sure. I used CAD to make my GTII centering rings, letting the tubes at 3.5 degrees cut the ring for me.

EDIT: Well now, I selected the body tube, inserted a Centering Ring. The default put it at the front of the tube. When I drug the location back, the "Drilled Holes" window magically popped up! Here is the template RS created..
Attached Thumbnails
Click image for larger version

Name:  RockSimCluster-8.jpg
Views: 33
Size:  242.7 KB  Click image for larger version

Name:  RockSimCluster-9.JPG
Views: 31
Size:  26.3 KB  
__________________
David Stribling
NAR 18402 SR
But it is rocket science!
Get yer Barrowmans here
Reply With Quote
  #5  
Old 01-18-2019, 10:19 PM
JumpJet's Avatar
JumpJet JumpJet is offline
Master Modeler
 
Join Date: Apr 2008
Location: Pueblo Colorado
Posts: 1,266
Default

So what your saying is I am Freaking Blind. I've been using that software for six years now and I've [U]NEVER[/U] seen that Cluster button.

Thank you very much.


John Boren
Reply With Quote
  #6  
Old 01-18-2019, 10:57 PM
rocketguy101's Avatar
rocketguy101 rocketguy101 is offline
frustrated aero
 
Join Date: Sep 2006
Location: Duncan, OK
Posts: 733
Default

Quote:
Originally Posted by JumpJet
So what your saying is I am Freaking Blind. I've been using that software for six years now and I've [U]NEVER[/U] seen that Cluster button.

Thank you very much.


John Boren

It took me a while to figure it out...I've only done 2 clusters with it, several years ago, and I didn't remember the CR trick until tonight
__________________
David Stribling
NAR 18402 SR
But it is rocket science!
Get yer Barrowmans here
Reply With Quote
  #7  
Old 01-18-2019, 11:24 PM
rocketguy101's Avatar
rocketguy101 rocketguy101 is offline
frustrated aero
 
Join Date: Sep 2006
Location: Duncan, OK
Posts: 733
Default

Here is a modified K-21 GTII I modeled back in 2013. I just learned tonight how to move the tubes out so they don't touch, so they are 0.49 from the center. That makes the bottom ring correct for the K-21 but the upper ring would need to be .407 to obtain the 3.5 degree cant each motor has on the actual model.
Attached Files
File Type: rkt GeminiTitan_K21.rkt (93.2 KB, 27 views)
__________________
David Stribling
NAR 18402 SR
But it is rocket science!
Get yer Barrowmans here
Reply With Quote
  #8  
Old 01-19-2019, 11:57 AM
Tau Zero's Avatar
Tau Zero Tau Zero is offline
Incurable SEMROC Fan
 
Join Date: Mar 2005
Location: Twin Falls, Idaho, USA
Posts: 2,035
Default

Quote:
Originally Posted by JumpJet
So what your saying is I am Freaking Blind. I've been using that software for six years now and I've [U]NEVER[/U] seen that Cluster button.
John,

As is the case with any other piece of software, the hard part is knowing where to look. (heavy sigh)
__________________
Jay Goemmer
"Centuri Guy"/"Tau Zero"
Semroc SAM #0029
NAR 86131


“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014
Reply With Quote
  #9  
Old 01-19-2019, 06:38 PM
teflonrocketry1's Avatar
teflonrocketry1 teflonrocketry1 is offline
Craftsman
 
Join Date: Aug 2007
Location: Whitehouse, Ohio
Posts: 217
Default

To simulate the effect of canted motors on a model rockets flight visit Apogees Peak of Flight Newsletter #226 "The Effect on Altitude from Canted Rocket Engines" by Tim Van Milligan https://www.apogeerockets.com/educa...wsletter226.pdf . A cant angle of only 2 or 3 degrees in the motor mount tubes will not make much difference in the flight chracteristics and it is probably not worth going through the trouble of creating the custom engines for the flight simulation.

To get the templates for the centering rings for canted motor mounts you will need 2 simulations; one with the motor tubes placed at the distance they will be at the top of the canted cluster where the forward centering is to be located and a 2nd simulation with the motor tubes placed at the distance apart in the mount where the aft centering ring is located. Then just print the forward and aft centering ring templates from the appropriate simulation.

By the way, you don't have to fly the same motors in each tube of the cluster. I have flown my FlisKits Deuces Wild with Estes C6-5 and B6-6 motor combination many times, all I did was match the sustained thrust and the total motor duration (thrust phase plus delay time). This should also work for the D12-5, E9-4 and the D12-7, E9-6 motor combinations, but I haven't tried these yet. http://www2.estesrockets.com/pdf/Es...rust_Curves.pdf
__________________
Bruce S. Levison, NAR #69055

Last edited by teflonrocketry1 : 01-19-2019 at 11:42 PM.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 03:44 PM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2019