Boosted darts

[Chris LaPanse]

I’m just going off that site I linked to (the “here” is a link if you click it). It claims 9000 newtons thrust for 1.9 seconds, with a peak velocity just a hair over mach 5 (3900mph), and then a LONG coast to 180000 feet or so.

I’ll note that it actually claims a much lighter dart than you are quoting. Here are the figures that I found:

Length (incl. booster): 2.63 m (8 ft 7.5 in); dart: 1.02 m (40 in)
Diameter: Booster: 7.62 cm (3 in); dart: 3.49 cm (1.375 in)
Finspan: Booster: 12.7 cm (5 in); dart: 8.6 cm (3.4 in)
Weight (incl. booster): 13 kg (29 lb); dart: 3.2 kg (7 lb)
Speed: 6275 km/h (3900 mph)
Ceiling: 55 km (34 miles; 180000 ft)
Propulsion: JPL 132A solid-fuel rocket; 9.0 kN (2030 lb) for 1.9 s

I also found specs for a super loki capable of 260000 feet, but that has over 50000 Ns (so it is up into the P range)

Length (incl. booster) 3.24 m (10 ft 7.5 in); dart: 1.16 m (45.7 in)
Diameter Booster: 10.2 cm (4 in); dart: 3.7 cm (1.44 in)
Finspan Booster: 20.3 cm (8 in); dart: 11.7 cm (4.62 in)
Weight (incl. booster) 29 kg (64 lb); dart: 6 kg (13.2 lb)
Speed ?
Ceiling 80 km (50 miles; 260000 ft)
Propulsion Aero Dyne SR110-AD-1 Super Loki solid-fuel rocket; 25 kN (5520 lb) for 2.1 s

Another one, the Loki-Wasp with the Loki booster (as opposed to the Loki-II) appears to reach just over 100k at mach 4 with around 11kNs:
http://www.designation-systems.net/dusrm/app4/hasp.html

[Anonymous]

John,

But it seems like your talking about “gravity separation” instead of “drag separation”. Just like dropping a hammer and a feather on the surface of the moon, wouldn’t drag be the deciding factor?

Could you RockSim it by putting a 1/4A in the dart and then runing the optimal mass function?

With regard to the sim, that exactly what I’ve been doing.

Regarding mass and drag… what got me going on all of this was an article at http://www.rocketryplanet.com/content/view/236/38/ That author had this to say:

“Basic Boosted Dart Theory: A narrow un-powered dart rides on top of a larger diameter booster. At burnout, the difference in drag separates the dart from the booster. By keeping the booster light, most of the remaining mass, and therefore energy, is retained in the dart and it coasts to a much greater altitude than the booster.”

That said, this guy did a lot of thing that were far from optimal. For example, he used an Acme fin can on the booster, which weighs about a pound by itself. Definitely didn’t keep the mass down in this booster. We are going to try to do just that. Also along those lines – you’d want a very fast burn motor, like Warp 9 or Blue Thunder. Negative gees will help separate the two.

BTW, darts are NOT allowed by TRA for altitude attempts. Don’t know why, but they are specifically precluded from the record books.

[Doug GerrardParticipant]

BTW, darts are NOT allowed by TRA for altitude attempts. Don’t know why, but they are specifically precluded from the record books.

Makes sense to me. Its a rocket altitude record not a dart altitude record.

[Anonymous]

BTW, darts are NOT allowed by TRA for altitude attempts. Don’t know why, but they are specifically precluded from the record books.

Makes sense to me. Its a rocket altitude record not a dart altitude record.

On the other hand, if you put a 1/4A in the “dart” which weighs 10#, you’d be eligible for the staged/complex record. Gotta draw the line somewhere…

Our old website had all the club’s rules for setting club altitude records, and IIRC darts were allowed for NCR records. Having said that, I don’t believe I could build a dart that would exceed any one of the club’s records. It is a cool concept, but I don’t think it is the most efficient way to get there (not for me, anyway). L-O-N-G burn motors would be my first choice, all other things being equal.

[elviss_boy]

This is a kind of project were there are so many different words that create the whole picture. There alot of ways to do some fial some work. I think with going to a perfect scale of the loki( which i did research ) isnt a good idea. Becasue there booster is very small with small fins and there booster was a solid rocket the whole way up…. and we want to get the booster back without going 20,000 feet. My hopes i dont know about John is to fly it at MHM give or take a month.

[Anonymous]

Kyle, I think we can get in the air by MHM as long as my work doesn’t interfere too much, and as long as you get all your homework done 😉 I’ll get with you in the next few days so we can finalize everything. I vote for an AMW L1300 for our first boost?

If we go w/ a 38mm dart, then we can just load up one of my existing rockets with lead (we need to add a tailcone, too!) but you still need to do all the work on the booster! The interstage coupler will take about a month or so to get done.

Are we going to let your dad help us? Maybe we can talk him into doing all the sanding 😮 Or perhaps he’ll go fetch it? Ha!

[Ed Dawson]

Can you say Nike Apache?

I’ve been drooling over the Performance Rocketry kit.

[elviss_boy]

HAHA a nike apache would be cool I guess but going through the work to get demensions and all that = more time. John i have no practive tommarow ill have time at about 1:00

[Bruce R. Schaefer]

By the way, I’m thinking of turning my dart out of stainless steel pipe. with a solid stainless nosecone.

Warren, that would take it into Amatuer Rocketry, far away from TRA or even EX TRA( ❓ ). BUT the key to a dart is accelerating the mass of the dart. Dude, that’d do it! 🙂

[Warren B. MusselmanModerator]

It would not be a problem at any TRA Research launch I know of – the safety code is written to say that basically if metal components are required for the bird to perform as specified, then metal can be used.

I have done quite a bit of research on boosted darts and already have design for a machined dart and all carbon and honeycomb booster that will surely break any waiver NCR ever will have on an M motor. Chris LaPanse rightly pointed out that the standard Loki Dart – a 7.5# and 38mm dart will hit 230,000′ on a full N (9,000 nSec x 1.8 Seconds) with booster deployment somewhere above the current NCR waiver of 20,000′. I’m thinking of a 100% scale Loki Dart with a booster section with a removable motor mount. With the mount in, you fly 54mm motors – with the mount out, you fly 75mm motors. Before I do something like that, I want to work out a video transmission system.

Warren

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