How long does it take to clear the rod with each motor. The D20 will give it a much better kick in the first, oh, somewhere around 20 ms, but after about 50 ms the C18 has higher thrust. By 200-ish ms there probably is more area under the C18's curve (impulse) than under the D20's.
Aw, shucks.
Is it possible to have the ORK file AND a file for Rocksim? I do not have Open Rocket, but I do have Rocksim.
I've had to install guides on the field before myself, so yeah it happens. I have some 1/8" printed to use, the idea being they can be replaced when damaged. I found my 3/16" rod so now I can do that size as well. But honesty how often are lugs damaged? I found a baggie with 1/8" and 3/16" lugs so I am probably going that route. And it'll have guides for rails as well.
Got ya. Welcome aboard.
OR won't save as a Rocksim file and I don't have Rocksim. I don't know maybe you can simply change the .ork extension to ... well whatever Rocksim uses. If someone has both versions maybe they can help out.
Not sure if you're talking about actually putting 1/8" lugs on this rocket.... but 1/8" lugs should not come anywhere near this rocket. Should be 3/16". Having buttons on the other side is good as well of course.
OR can save as Rocksim, using the Save As... dialog. However, I'm not sure if *everything* gets carried over; certainly some things do not import perfectly when you read RKT files into OR. Motor selections, in particular. Someone with Rocksim should verify and do cleanup on the file afterwards.
Darn it! Neil beat me to it...
Hmm. Even without computing the area under curves, it should be right that shorter rail exit time means higher rail exit speed. The exit times fall exactly in line with the average thrust numbers. Contrary to what Neil found. Weird.
Youch, that's heavy. 0.37 oz (10.5 g, the mass of 2 US nickles) doesn't sound like much to an HPR guy, but in the LPR world it can mean quit a bit, especially when it's at the aft end. The adapter won't be facing the kind of abuse that the exterior components will, so it can be made very light out of cardboard. All it takes is a small piece of BT-20, an engine block, two 50 to 20 centering rings (either balsa or doubled up card stock) and an engine hook. I made one a while ago that hardly weighs anything.
Below you say is 0.27 oz. Again, it's trivial for HPR, but not for LPR. Small yes, but not trivial.
KISS. The Estes retainer isn't hard to use, but don't add unnecessary complexity or mass. Squeeze out weight. Squeeze extra hard when it's aft end weight.
) and fin tabs; and there are a few tricks I can use to shave a little here and there. A wood or paper CR up front will help some, the fin tabs will hold the MMT once everything is assembled. I think I can remove enough glass to account for the added mass of the epoxy.
I don't expect to gain much from the epoxy, and I am fairly certain I can make it up elsewhere.
Gotcha. I've had a stash for some time now I guess. Never knew they went away. Either way. The C18 will work. If I can get the larger field I'll test fly on the C18 and a D15...maybe a D12.
I’m in if it heads my way in spring, weather up here isn’t conducive to much of anything for a while and I don’t want to be an issue.Updated list. We are getting there. May have one more here in Louisiana. I expect a few more as there are some participating in the TRF Traveler that seem to be under the impression that they are one and the same. We'll see.
- shawn_rocket ---- Missouri
- jbrracer ---- Indiana
- Wally Ferrer ---- Virginia
- Tobor ---- Illinois
- bobbyg23 ---- South Dakota
- dhbarr ---- Oklahoma
- jqavins ---- New York
- CPUTommy ---- Massachusetts
- rdbrown ---- Kansas
- Tractionengines --- Ohio
- Sooner Boomer -- Oklahoma
- tsmith1315 --- Georgia
- TheTank ------ Connecticut
- tcblightning ---- Arkansas
It was brought to my attention that not everyone has Openrocket or Rocsim and I can't wrap my head around that idea. LOL. I had Openrocket before I had rockets to fly. So I am posting the sim results and a brief write up on said results. Now to those of you who know OR inside and out...I may have missed a detail. I have about 14 iterations of this thing in my sim folder so be gentle. Mass and Cg will change after it is assembled. I will mark the CP, and maybe empty CG, when complete and come back here with the updated file(s). Omitting the retainer doesn't help enough for me to fool with the hook. I will save some mass when I mod the MMT (yes I fixed that you witch hunters
View attachment 445797
View attachment 445813
The wedges on the front of the fins are there to fill the empty fin slots and give it a little bit better profile than just plain ole fins. Removing them helps a little with the mass and stability but not much. The fin tabs will be cut as needed so the file doesn't reflect them perfectly. This will put it at .98 CAL on the mighty D12, over 1 on the C11. Even the F39 has .69 CAL. If that doesn't sit right with you but you insist, smash a half ounce of clay into the tip of the nose cone. But this rocket at that altitude, may want a tracker and a few more eyes. These sims are run on a 3/16" rod, at 34" long. Kick that up to a 42" rod and they all get well over 40 ft/s. I don't know when it is necessary to jump up to a 1/4" rod or a rail but I would suggest the F's be flown on one or the other.
I am sending it the printed adapter. I loaded PLA+ and it prints wonderfully. I don't care if I ever see PETG again. I can play with the design and lighten it a bit but feel free to build your own adapter if you want a lighter version. Or even take a drill to one of the white ones I am sending. The white ones are plain PLA, black ones are PLA+.
I will put a simple 3/16 lug on one side, conformal 1010 guides on another. Printing interchangeable 3/16" and 1/4" lugs seems like an unnecessary complication. If the group thinks it necessary I will gladly do so though. I may again get the feeling to under-simplify things and look harder at it.
I invite the makers to design/print a coupler A/V bay for it so it can be flown DD if anyone so desires. I am willing and able but it wont be done quickly. If anyone wants to do it I can send the piece I cut off so they can get the dimensions correct. I can also send along an Eggtimer Quark.
@rdrown
I did my best with the RKT version. This is how it saves. I can go in and add motors and sims, adjust the dimensions and when I save it loses all that. You will need to reconfigure all the pieces. Sorry about that, but it is what it is. The drag, mass and Cp stay the same. The Cg changes for the better and the RKT version has better results all the way around.
@DeepOvertone @neil_w @KC3KNM
I know you aren't signed up, but you showed interest.
I’m in if it heads my way in spring, weather up here isn’t conducive to much of anything for a while and I don’t want to be an issue.
Also, if you guys need any bits or pieces machined, I’d love to help out. Doesn’t seem like there’s anything, but I’ve got weekends free in the shop again for a little while.
Someone correct me if I'm wrong, but I do believe that the need for heavier rods or to go to rails has to do only with the weight of the rocket, not the enfine choice. If the weight means a 3/16" rod is OK for a D12 then it's OK for F engines. At this weight, the concensus seems to be that1/4 inch is a better idea; if so then it's as needed on a C18 as on anything else.
Not sure the problem. Send me your email through conversation and I'll email them to you.
You are likely right. I didn't know if high thrust motors may cause excess rod whip. I don't scratch build and fly small rockets enough to know. I do build Estes kits but use the guides included with them. Unless of course it is big enough to accept buttons.
