Talk:Zenit (rocket family)

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Talk

I yanked this section on an unrelated rocket with a different name.

Zenith is also the name for one in Switzerland developed sounding rocket, which has nothing to do with the Russian rocket Zenut. The sounding rocket zenith was a single-step rocket with a length of 5.6 meters, a diameter of 0.42 meters and a takeoff weight of 610 kilograms. This rocket, which was propelled by solid-propellant engine, which supplied a thrust of 45kN in the starting phase and in the further flight phase of 22kN, could carry a pay load of 25 kilograms in 210 kilometers height or a pay load of 130 kilograms at a value of 115 kilometers. With its maiden flight on 27 October 1967 of Salto di Quirra those reached zenith a height of 145 kilometers. The zenith was later only twice started "Cuckoo" on 30 July 1971 by Salto di Quirra with a British rocket of the type; as starting stage as well as on 13 December 1973 of Andøya likewise with a British rocket of the type "Cuckoo" as starting stage. [ 1 ] (http://www.univ perp.fr/fuseurop/zenit_e.htm) an elevator research rocket of the type zenith is eye-posed before the Hermann Oberth museum in Feucht (near Nuernberg).

-Joseph (Talk) 00:36, 2004 Dec 29 (UTC)

Zenit rocket → Zenit

Four tiny articles are disambiguated at Zenit. One of them may as well get the main title. The rocket launch vehicle that's currently being used to launch several nations' satellites seems like the most prominent choice. —Michael Z. 2005-01-27 02:08 Z

Oppose. There have been too many different things named "Zenit" in Soviet Union and Russia. — Monedula 07:45, 27 Jan 2005 (UTC)
Oppose. From where I come from, Zenit photocamera was much more popular that Zenit rocket ;) ←Humus sapiens←Talk 08:50, 27 Jan 2005 (UTC)
- Agreed. Also Oppose. —ExplorerCDT 15:36, 27 Jan 2005 (UTC)
Oppose. To me, Zenit means FC Zenit Saint Petersburg, which I've just added to the list. sjorford :// 09:49, 27 Jan 2005 (UTC)

Accuracy of weights

Sources say 6067kg or 6080kg for latest satellite launch, this is due to a conversion error from lbs to kg (or vice versa) with 13376lbs being the common number. Question is which was the original weight measurement: lbs or kg? If it was kg then the lbs should be refined to at least 13400: significant figure should be taken into account which means that if 6080 was the original measurement only 3-4 significant figures should be taken in any calculation (which means 13376 is erroneous outright), if 13376lbs was the original measurement then 6067kg or 6067.3kg would be the most accurate conversion. --BerserkerBen 22:31, 26 Apr 2005 (UTC)

Don't know what to say, we simply don't know which number is the accurate one. If we assume, that 13376 lbs is the measured one (because of such an unrounded number), then 6076 kg is right. But if we assume that 6080 kg is the mesured one, than 13376 lbs could be calculated if they would use 5/11 as multiplying coefficient between lbs and kg. Do you know another sources to look for the right weight? The only trustable source that I know is Boeing, all other news agencies and so on simply copy the weights from their news release --Bricktop 00:38, 27 Apr 2005 (UTC)

Well accroding to these it weighs 5993 kg (13201 lbs) it still breaks the record though.[1] [2]

The first source says on another page [3] 6080 kg and notes that his informations are from Boeing website. Your second source is a bit too old :-), they give 2003 as the planed launch date for the first satellite (indeed launched on 26.5.2005). So the changes in satellite weight are very likely since then, for a launch vehicle reason or more fuel or something else. I would say we should keep 6067 kg, it sounds the most probably for me --Bricktop 02:13, 27 Apr 2005 (UTC)

The Sea Launch website indicates that the satellite they put into orbit was "6080 kg (about 13,376 lbs.)" --Kralizec! 16:53, 27 Apr 2005 (UTC)

Well, what now?:-) Is 6080 kg the accurate one? --Bricktop 17:27, 27 Apr 2005 (UTC)

The satellite's manufacturer states on their website that it weighs "6,080 kg (13,376 lb)," so I updated the article with this number. --Kralizec! 18:10, 27 Apr 2005 (UTC)

6,080 kg = 13404 lbs, 13,376 lbs = 6,067 kg. what is the right one? See discussion above --Bricktop 18:37, 27 Apr 2005 (UTC)

Changed it to 6080kg/13376lbs as those are the numbers used by both the company launching the satellite and the company that built it. To reflect the vague conversion numbers (aka 6080kg actually equals 13404lbs), I used Sea Launch's "about 13376lbs" hedge statement.--Kralizec! 18:59, 27 Apr 2005 (UTC)

Now come on this is ugly: "Sea Launch [4] indicates that the satellite they put into orbit was "6080 kg (about 13,376 lbs.)" and the satellite's manufacturer, Boeing, states [5] that it weighed "6,080 kg (13,376 lb)," however 6080 kg actually equals 13,404 lbs. Using the rule of significant figures we assume it weighed ~13,400 lbs." could this be shortend or linked to the disccusion, or linked to the Spaceway1 article?

Agree, it's indeed out of place in this article, as this hasn't much to do with the Zenit rocket itself. Schould be moved to Spaceway1 article --Bricktop 23:10, 28 Apr 2005 (UTC)

there I did it, hope that will do. --BerserkerBen 23:30, 28 Apr 2005 (UTC)

Good idea! Now if only someone had thought of it about ten edits ago. ;-) --Kralizec! 05:17, 29 Apr 2005 (UTC)

It's easy enough to figure out what likely happened here. Just look at the fact that 13376/6080 = 2.200000000. That was most likely used as a multiplicative conversion factor, so the last conversion was likely made in the direction from kilograms to pounds.

However, that may not have been the only conversion. There may have been another conversion involved before the last one. What happens if the original number was 13,400 lb, and we convert it to kilograms? If the exact conversion factor is used, before rounding the conversion would be 6078.137758 kg. Now it needs to be rounded appropriately. One rough rule of thumb often used is to look at the number of significant digits in the original, in this case three. Rounding the result to three significant digits gives us 6080 kg. It doesn't even have to be the exact conversion factor that was used, if the person doing this used 0.4536 kg/lb instead, 6078.24 would still round to 6080. Even using 0.454 kg/lb, 6083.6 still rounds to 6080.

But this is a Ukrainian rocket, so they wouldn't have originally measured this in pounds. If they did not provide this information, however, the number might come from some American estimate, or even someone else's estimate, and that might have been in pounds.

But what if the original were 6100 kg? With no other information, that is best converted as 13,400 lb (using the precise conversion factor, before rounding it would be 13448.19... lb). I'd guess that that is the most likely original. Even if somebody had measured it more precisely, that is likely correct to the precision we can imply from it. Gene Nygaard 05:48, 2 May 2005 (UTC)[reply]

I normally don't argue for removing details, but this "record" is broken with just about every second commercial launch. It will be broken again at least once this year (iPSTAR), and there are even larger commercial spacecraft currently on the drawing boards. Once iPSTAR is launched (~Jul. 7), I'm planning on removing this text from this article, and not recording EADS' technical triumph du jour on Ariane 5. What makes this info even more uninteresting (with respect to launch vehicle achievements) is that every commercial spacecraft in orbit is dwarfed by typical NRO spacecraft. —Fleminra 23:56, Jun 17, 2005 (UTC)

Sea Launch User's Guide claims the maximum payload capacity to GTO is 6,066 kg. So maybe the 6,067 kg number for Spaceway-1 weight is really right? ;-) --Bricktop 22:44, 22 Jun 2005 (UTC)

With Arianespace's launch [6] of the 6,485kg THAICOM 4 (IPSTAR) communications satellite, this article's contentious record-breaking weight issue is now moot. --Kralizec! 12:27, 16 August 2005 (UTC)[reply]

Units of Specific impulse

Why not state it in seconds instead of a much longer and space consuming form such as lbf·s/lb,kN·s/kg, ect. There is no universal standard for stating specific impulse. And to make it worse any source that states a specific impulse in seconds cannot be converted into lbf·s/lb or kN·s/kg because there is no assurance that the force are measured in empirical or metric. For example the site I got the Isp for the Zenit rocket only states it in seconds,[7], now we can assume the source was from the Ukraine and it should be metric, but that is not a guarantee. --BerserkerBen 04:37, 2 May 2005 (UTC)[reply]

Lots of different units are used, here as in many other applications. However, as in most cases, if you are going to use only one unit, the current recommended practical system of units is the International System of Units. The SI units of specific impulse are newton seconds per kilogram.

Now you are being downright silly, in your irrelevant claims of "there is no assurance that the force are measured in empirical or metric". For one thing, just look at the table—the thrusts there were listed in obsolete metric units (which may have been the ones originally used), and they were also listed in the SI newtons.

The conversion factors for specific impulse are simple enough

1 "second" ≡ 1 lbf·s/lb ≡ 1 kgf·s/kg in other FFU
1 "second" in terms of SI units ≡ 9.80665 N·s/kg ≡ 9.80665 m/s
of course, 1 N·s/kg ≡ 1 m/s. Note the significance of this; in FFU, whether English or metric, the number for a "specific impulse" in seconds (or in lbf·s/lb or in kgf·s/kg, all the same thing) are different from the numbers for the very same measurement expressed in different way, usually called effective exhaust velocity. How much different depends on whether you are using English units of ft/s or metric units of m/s for effective exhaust velocity. However, in SI units, This one measurement is only expressed with one number, no matter which way you express the units: newtons seconds per kilogram are exactly the same thing as meters per second.
Pounds force don't actually have an "official" definition. But assuming the same acceleration is used to define pounds force as is used to define kilograms force, as is most common today, 1 lbf·s/lb ≡ 9.80665/0.3048 ft/s ≈ 32.1740 ft/s
1 ft/s ≡ 0.3048 m/s ≡ 0.3048 N·s/kg.

Furthermore

The symbol for kilograms-force is not "Kgf"
Kilograms force are not SI units.
The symbol for seconds is "s" not "sec"
It isn't right to have "length" and "Diameter"
There should be a space between the numbers and the units of measure

Gene Nygaard 05:28, 2 May 2005 (UTC)[reply]

the thrusts there were listed in obsolete metric units (which may have been the ones originally used), and they were also listed in the SI newtons. does not guarantee that its in N·s/kg. but if your not going to change your mind on that space can still be saved by stating "I_sp (kN·s/kg)" in the first line instead of writing it twice.

Your last change it incomprehensible. It just doesn't make any sense to say

I_sp<sub:> (N·s/kg)		330 s (vacuum), 305 s (sea level)

Just what in the world do you suppose that "N·s/kg" is supposed to mean in this confused expression? If it is in those units, it is not in "seconds": 330 seconds = 3,200 N·s/kg. Maybe reading specific impulse would help you? Gene Nygaard 13:22, 2 May 2005 (UTC)[reply]

Even better then: just removed the "s". Maybe you should calm down before resorting to presumptuous insults. --BerserkerBen 14:41, 2 May 2005 (UTC)[reply]

B-class?

Does this article meet the criteria for "B-class" yet? In particular: Y is it suitably referenced, and are all major points appropriately cited?

Y does it reasonably cover the topic, and not contain major omissions or inaccuracies?

Y does it have a defined structure, including a lead section and one or more sections of content?

Y is it free from major grammatical errors?

Y does it contain appropriate supporting materials, such as an infobox, images, or diagrams?

(sdsds - talk) 04:41, 2 October 2007 (UTC)[reply]

Overlapping subarticles?

Zenit-3F: "The Zenit-3F, Zenit-3SLBF or Zenit-2SB/Fregat is an Ukrainian expendable carrier rocket."
Zenit-2M: "The Zenit-2M, Zenit-2SB or Zenit-2SLB is an Ukrainian expendable carrier rocket"

Looks like these articles overlap quite a bit. For example, both claim to be about Zenit-2SB. I'm not very familiar with the different versions and the naming scheme, but it looks like some merging and clarification is needed here. Nanobear (talk) 22:29, 22 January 2011 (UTC)[reply]

Zenit-2SB is the two stage version which forms the first two stages of the modernised three-stage configurations. I would strongly oppose any mergers per precedents for other such families of rocket. --G W… 23:07, 22 January 2011 (UTC)[reply]

Thanks for the clarification. So the version number (2 or 3) means the number of stages? Btw, if you can, maybe you also answer my question at Talk:2011 in spaceflight. Nanobear (talk) 23:17, 22 January 2011 (UTC)[reply]

I don't know if it was intended to, but it does. The naming is quite confusing: Zenit-2 was the old two stage version, Zenit-2M is the new two stage version for Russian Government launches, however it would be known as Zenit-2SLB if it were to be used for a commercial launch (nobody has ordered one yet). The designation Zenit-2SB also applies to these, however this only seems to be used when an upper stage is present. The SL stands for Sea Launch. 3SL is the three-stage version with a Blok DM-SL upper stage, 3SLB is the modernised version with a Blok DM-SLB upper stage, and Zenit-3M would be used to denote a Russian government version of the 3SLB (again, this is unused). Zenit-3F is the three stage version with a Fregat upper stage (presumably F for Fregat), it is also known as Zenit-3SLBF (possibly a hypothetical commercial version, but it is not offered), and 2SB/Fregat (probably for parity with Soyuz/Fregat, which do not have a name for the combined vehicle). There was also a Zenit-3, although it never flew. My understanding is that it would have been fairly similar to the 3SL, with a Blok DM upper stage. --G W… 23:38, 22 January 2011 (UTC)[reply]

Status of Zenit program (February 2015)

Well, the Russians have claimed that they will no longer order any Zenit rockets in the future, but the same article also claims that they have 2 more vehicles produced and assigned to satellites (for Elektro-L No.2 & Spektr-RG), as well as another without engines for the (now suspended) Ukrainian communication satellite Lybid'. Plus this is a one-sided statement (look at the Dnepr status for example; there are disputes whether they are stopping the program) and I doubt that the Ukrainians would claim the same thing.

So, what to do with that section? I don't think the current representation is completely accurate, but I'm not sure deleting it is the correct method to deal with it either... Galactic Penguin SST (talk) 06:23, 8 February 2015 (UTC)[reply]

Hmmm. If there is more in the article that I used to source that edit, you can feel free to just update the prose in the ordinary Wikipedia process of evolving improvement.

But I'll take a look at it, and endeavor to clarify that there are a couple of flights in the pipeline prior to the shutdown, etc. I'll be done in ten minutes or so. If you'd like more, or think some other prose better, edit away. That's how this great encyclopedia is built. N2e (talk) 06:42, 8 February 2015 (UTC)[reply]

OK I remembered wrongly - it was in another (Russian) article that the disposition of existing Zenit rockets was listed. I'll add it to the article soon. Galactic Penguin SST (talk) 07:00, 8 February 2015 (UTC)[reply]

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