SSSS / SSS

[Warren B. MusselmanModerator]

I paid for 7 and the upgrade to 8. I use 7 for most of my stuff because 8 seems to be over optimistic all around on sims. 7 seems to be right on vis a vis optimal weight simulation, 8 – because of the overoptimistic sims, I haven’t messed with so much, though I do like some of the features better.

With all the sim programs, the biggest problem I’ve run into is the quality of the motor files. While many motors seem dialed right in, quite a few are not. There are glaring errors even in manufacturer’s .eng files on stupid stuff like casing length and even diameter. In cases like the G80 or the J350 where there have been more than one version, there is little to differentiate the versions.

In the club launch logs for this site, our motor database is even more fouled up than the Rocksim files. I’ve heard the same complaints from SpaceCad users too. I’ve been working to correct this, (and also create a clean set of .eng files for Rocksim) but with 500+ motors, this is a huge clerical effort and quite frankly I’m more interested in vacation right now. I’ll probably get to it this coming fall/winter.

[Bruce R. Schaefer]

Warren,
When you get those files cleaned up, post them. We’d all be very grateful. That is one hell of a daunting task. Most would probably pay you for them. Sell them on the Internet. SpaceCAD uses the same .eng files that RockSim does.

[denverdoc]

Yea, I think with the sub-mach stuff and good motor data, Rocksim does fine. Its Mach plus where it breaks down, largely due to the Datcom methodology imo. I noticed no diff in sims between v7 and v8 and even queried Apogee founder on this during the annual mtg. He was unaware of any changes in the basic computational engine. But his partner does the physics poriton so possible some changes were made Tim was unawares. What I want it still won’t do–which is accurate drag calcs at greater than Mach 1.5, strap ons, BG stability, unusual staging, etc. That said at 100 bucks still a marvelous product.

But in where it counts for me–high performance rocket sims–see v8 as a huge disappointment with more video game features added and no beef. I think the aero stuff is more accurate at transonic flights but is unfortunately ergonomic wasteland.
JS

[denverdoc]

BSchaefer wrote:

Absolutely, J! I remember an IBM 360 that took up a house, and you had to punch the program on cards! But that was then… 🙂 I worked out Barrowman’s CP calc in Excel. Doesn’t agree with modern CP calculators as I thought it would, but certain assumptions were in the orignal equations. I always split the difference. 🙂 I’m still setting the MAWD at 2 sec. mach delay. Not gonna happen, but, hey, I’m forever hopeful. :)/quote]

Bruce,

PM me with more details, as I understand it, the one assumption that has been under attack (forgive the pun) is the lifting force provided by the AF at high AOA’s. Tends obviously to destabilize skinny rockets that may start life fine but weathercock and then loop de loop. Other than that it has not been altered so if you’re getting discrepancies from the original centuri or nar or even his masters thesis which can be find online, then beware. Now rocksim has its own proprietary method of computing static stability which tends to me more generous than Barrowman’s, but when it says Barrowman, it should be in strict agreement.

[Author]

Posts