Craig

I'd be happy to look over my designs you listed.

I also posted two SLS kits over in the Potential SLS kits? thread.

http://forums.rocketshoppe.com/showthread.php?t=1408

I had a SLS Magnum-D Hornet & a SLS Lune R-1 design there. The SLS Lune R-1 has been flight proven and I have a few build and finish pics of that one.

Would BARCLONE be interested in either of these?

.

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Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

Steve,

Thanks for the heads-up. It's been some time since I looked through all of the SVDT threads. Yes, I'd be interested in those as well!

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Craig McGraw

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SAM 0044
AMA 352635

Carl,

It's been quite a while since this was mentioned, but have you had any additional requests for a smaller set of Nike-Smoke nose cones? I'm looking at revising this design and was wondering if you could add it to the list? I think my pattern in the RKT file is close for measurements.

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Craig McGraw

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SAM 0044
AMA 352635

Actually, a version for ST-20 would be nice, too! (But it would be for a clone, not an original design. )

Mark \\.

__________________
SAM # 0011

I revised and posted one of the two you mentioned on your list as well as the two I mentioned. I'll look for others.

I'm going to rework the Mach-1 Dart file. All my FSI files I entered into RockSim were originally version 5 files and used FSI parts so I need to rework them with Semroc parts. I have flown the Mach-1 Dart many times using a motor mount in a mock up booster and it always flew well.

.

__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

The acronym stands for "Low Earth Orbit Payload System".

This is a design that uses the new (not yet announced) ST-6 tubes that Carl has announced for his "Deci-Scale" series. They're a little larger than ST-5, but smaller than ST-7 (well, duh... I knew that! ). You can fit a length of ST-5 inside them and still need centering rings (narrow, fragile, but still possible) for use as motor mounts.

Length: 20.75"
Diameter: 1.34" (ST-13)
Fin Span: 3.10"
Weight: 1.15 oz


1/2 A3-4T......282'......Dv 8 FPS......36" x 1/8" rod


Once Carl officially reveals the ST-6 tube and components, I'll post this to the "Studio" thread.

Enjoy!

Attached Thumbnails

   

Attached Files

LEOPS.rkt (145.3 KB, 5 views)

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Craig McGraw

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SAM 0044
AMA 352635

Over on the Designer's Studio thread (mainstream area), RKT2K1 shared his version of the Centuri Bulldog in RockSim format. His simulation runs were marginal and had very high Dv numbers. I noticed in the kit instruction scans that the B8 and C5 were listed, which made a lot of sense. This design appears to have been a pig from the get-go; yet the performance even with the listed core-bores was not really in the ballpark. So I tried the design out with some of SEMROC's Secret Sauces, and spotted an interesting simulation. The B14-4 has a very nice flight profile, with a Dv of only 15 FPS, and an altitude of 263'.

Now, I've never personally had any experience with this model. I'm only going on what Bill [RKT2K1] described in his post. The simulation he worked up seems to be on-par with his recollections of the original kit. Is there anyone here in the SVDT who has or had the Bulldog kit? What are your recollections as to its performance, and what engines did you see the best flights with? Am I wrong about the kit being more a sow's ear instead of a silk purse?

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Craig McGraw

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SAM 0044
AMA 352635

I don't recall if it was discussed in that post, but why not just upgrade the whozis mount to 24mm? The tailcone adapts down from BT-70 to BT-55, so instead of sticking a BT-20 mount in there, why not go with a BT-50/ST-9 mount instead? Heck, you could even go with an LT-115! Or a 3 x BT-5 cluster! I don't know how these would sim, but I would think that there ought to be something there that works. I think that the Centuri Bulldog is a very attractive model, and it is one that I would certainly want to build.

Mark \\.

__________________
SAM # 0011

Though, a bit of bad news first. It seems like RockSim doesn't like my design when it comes to getting any useful flight-testing results, so in that respect, it is "virtually-unproven" until Apogee works out what's wrong (I'm going to email them later this weekend, but I'll wait first to see if someone is able to point out something that I'm missing).

That being said, I now present the first functional strap-on design for this thread (I think). I was at a loss for a name while working on it, so I just called it, "Straponski" until I can think of something better. I thought it sounded vaguely Russian (even though the design is loosely inspired by the Ares V). It is based on ST-20 for the core vehicle, which has a large (33.9 cu. in.) payload for launching cameras, experiments, etc. I have a somewhat limited knowledge of how passive strap-on designs work; what I've gathered is that the strap-ons are designed to accelerate faster than the core throughout their motor's burntime, thus holding them in place, and at burnout, drag forces them to slide off their rails/holders, as the core continues burning. I didn't actually run calculations on the core vehicle and strap-on approximations to see if the acceleration worked for various motor combinations, I just guessed that an 18mm motor mount in a ST-11 based, lightweight booster would accelerate faster than a big, long piece of ST-20 on an E9 or other longer-burning core motor (carring a payload would expand the motor range a good bit, if any of these setups are too close to call). Anyway, I also wanted the strap-ons to not just fall away, but "peel off" like they do on real space vehicles. The way I planned on doing this is just something I came up with in my head (and later sketched out on paper), and involves a short section of dowel rod, mounted horizontally, attached to the base of the core stage. The strap-ons would have a corresponding section/slice of launch-lug material towards their base, and when the standard strap-on lugs have allowed the booster to slide backwards, instead of falling off the rocket, the launch leg slice would hit and wrap around the dowel, creating a hinge on which the base of the booster pivots as it falls away. A small piece of balsa might be needed up higher on the booster to give it a slight "kick" to get the rotation started, to make sure it doesn't just hit the dowel rod and get stuck there. I've tried to make the RockSim file as accurate as possible, so it will probably make more sense when you look at what I've set up by looking at the 3D exports and RKT file. The boosters can be held in place at launch using a piece of thread that wraps around the lower attachment point and over the nozzle of the motor; if it lights, it will burn through the string, freeing the booster to slide; if there is a misfire, the string will remain to keep the booster latched in place--just in case it should happen to ignite late. The completed rocket comes out at exactly 36" long (I actually had to modify the nose cone a bit to do this... it was originally 4.5" long, but when the length of the rocket came out to 35.7500" long, I couldn't pass up the opportunity to make it an even 3 feet. So it's got a 4.75" ogive now.).

Now, to those simulation results...

The rocket only weighs about 6 oz empty, so it ought to have decent performance on 2 18mm's and a 24. However, RockSim has been acting strangely, and is only giving me altitudes around 50-100 feet for all flights (For instance, 2 C6-3's and an E9-6 went to 51 feet, maxed out at about 19 mph (according to the flight summary--though according to the data plot, it really only reached 8 mph), had an optimal delay of 0.19 seconds, and strangest of all, apparently reached stable launch speeds at -36.37" (that's NEGATIVE!). Looking at the 2D flight profile, it almost seems like it's simulating a ridiculously high Cd, because the rocket just chugs along while under power, stops right after burnout, freefalls *very* slowly, deploys its parachute and drops very quickly (relatively; DR's are comparable with other rockets, but the rest of the flight goes so slowly that descent under parachute is actually the fastest part). However, a high Cd value would not explain the strange -36" minimum launch rod length, nor the fact that, according to plots, it really cleared the rod at less than 2 mph, and yet it continues to fly in a stable manner (according to the simulation results, it apparently cleared the launch guide at 18.7 mph... I give up). Also, RockSim is rendering strange tube-like objects when I look at the 2D base view (see attached) that I am at a loss to explain (I didn't create them, and they show up nowhere else). Similar results happen, even when I try to simulate with the strap-ons off (ie, checking the "Mark this pod as ejected." box in the Pods interface), flights on a single E9 barely differed from the flight on E9's and C6's.

So, as far as I can tell, something is just very wrong with the program, or I really messed something up. I'm using the lastest version (9.0.2f72), as far as I know.

Anyway, enjoy, if possible.

Straponski
Length - 36"
Diameter - 2.04" (Core; ST-20), 1.17" (Strap-ons; ST-11)
Fin span - 8.04"
Weight - 5.89 oz

Simulations

n/a

Attached Thumbnails

         

Attached Files

Straponski.rkt (176.8 KB, 6 views)

__________________
David Hash
NAR#77967
http://www.Semroc.com

Whoops, of course I forgot the launch lugs. I was tired!

I'll add them on in a bit; ought to just be a couple of 3/16" lugs (2" long), spaced about 6-10" apart, centered in between the fins of the core tube.

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David Hash
NAR#77967
http://www.Semroc.com