1800 ft (presumably on a C engine) claimed for the Starfire (see Earl's post above).............can that be real?

I do have Office but was not aware of the on-line converter for pdf spreadsheets. Having just finished a super-fun plumbing job here (well, that is a dumb statement; what plumbing jobs AREN’T super-fun??!) and feeling sorta lazy, do you have a pointer to the online converter?

Earl

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Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

That does seem a bit generous, no? I can’t absolutely say it won’t reach that altitude since I have never flown one. But, I would be a bit dubious of that claim. I have wondered over the years about a number of manufacturers altitude claims in catalogs and kit instructions.

Earl

__________________
Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

Based on this one flight: https://flightsketch.com/flights/1151/, I'd give it, maybe, 1500 feet on a C6-7. A Q-jet C12-8 could put it to 1800 feet I'm pretty sure, but they didn't exist back then.

My model is Semroc retro-repro, and perhaps with a little more care in finishing it would fly a little higher.

I've flown enough altimeter-equipped flights now to be pretty sure than most (but not all) projected altitudes given by Century or Estes are optimistic, sometimes quite a bit optimistic. One of the exceptions is actually the now-50-year-old Alpha III which can touch 1100 feet on a C6-7.

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Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE

Estes used to claim 1600 ft on the larger diameter BT-50 Astron Sprint (boat tail, ogive nose) on a C6-7. It would get there. Based on this, a ST-8 Starfire may have hit 1800.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !

I can see the Sprint on a good day with a hot C6 hitting 1600',
and maybe the Starfire on the same day with the same motor could hit 1600', but with much draggier fins and being 2'' longer, 1800' seems like a stretch even with the slight difference in diameter. It would be a fun project...

__________________
SAM #0031

Hmmm. . . .

I have originals of both, a new pack of C6-7s and an Altimeter II. Gonna need a streamer from that altitude on the Starfire, but other than that, should be doable for my next launch. We'll find out.

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NAR 79743
NARTrek Silver
I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7

Bernard, was that a Semroc Starfire carrying an altimeter? What is the weight of your altimeter, and how do you correct for its weight to determine rocket altitude without the altimeter?


Joe

Fly it again and divide by two.

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Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc - Starfighter Scorpion Centuri - Mini Dactyl Estes - F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc - Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark

Yes, a FlightSketch Mini in a small fleece pouch. The data I linked to is from that altimeter.

I have not compensated for the mass, which in this case is ~4g. I just report the observed results.

John Boren has asked me about this in cases where I've whined at him about wildly optimistic altitude projections, which for recent designs he told me are from RockSim. In a small model I can see the added mass of the altimeter being a factor, I suppose. One recent case he and I have discussed is the neat little two-stage mini-motor model called Checkmate. They claim "over 900 feet". I build mine with a small payload compartment from the top 1 1/2 inches or so using a short coupler and a fiber disk from Apogee, and fly one of the small altimeters in that compartment (FlightSketch, Adrel, Firefly). These mods plus the electronics probably add 4-5g. I've never seen more than a touch over 700 feet on many flights A10-0T to A3-4T, even when the boost and sustainer both go perfectly straight up. I even tried a couple of really old A3-6Ts in the sustainer to see if a longer delay would get it there. Nope.

John and I had quite a conversation about the Sterling Silver (a recently released minimum diameter two-stager for 18mm motors, also known at Hobby Lobby as Epic II). He showed me the results of some of his simulations for it, and even ran a couple with a bit of extra weight aboard to simulate my altimters...but still they were optimistic relative to my actual results.

On the other hand, my comment in the prior post about Alpha III is based on actually seeing 1100 feet with 4g of FS Mini and fleece pouch tucked up inside the nose cone.

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Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE