Agni -> Surya?

ramana · Post by **ramana** » 25 Oct 1999 12:13

I am not an aero guy. I am a mech design eng. I would like some aero type to look at these configs and make an educated guess. I wrote this after the A-II test and the Lok Sabha dissolution. Here it is. A to SAfter the successful testing of rail mobile Agni-II, it is clear from its range, that it was designed to be useful in a regional context. With this India has a number of flight qualified solid fuel motors. The recent NATO summit has expanded the roles and missions to out of area. It has taken on a counter-proliferation mission and in addition has expressed interest in South Asia. The daily barrage of leaks from US about the vast amount of nuclear data (proliferation?) transferred covertly to China is very disturbing. Not only various weapon designs but re-entry vehicle designs were transferred. Add to this the 'inadvertent' overt transfer of launch vehicle technology via the Hughes and Loral affair. Dr. Ming Zhang’s recent paper at the Carnegie Endowment for International Peace (www.ceip.org/pubs/pubschina.htm) makes it clear that China is revising its policies towards India. It is time to examine what options India has in this regard.The ISRO and DRDO programs have given India the following, flight qualified solid fuel motors or those which are within their capabilities. All assume HTPB with Isp = 260 (sea level) and 280 (vacuum). The mass fraction is taken to be .85 (conservative). Name Diameter(m) Length(m) Weight(t) Comments PS-3 2.08 3.5 8.5 PSLV stage 3 PS-3-S 2.08 7.0 17.0 Stretched PSLV stage 3 SLV-1 1.00 10.0 10.0 SLV stage1 AII-2 1.00 5.0 4.0 Agni-II stage 2 RV 1.30 4.6 1.5 Agni-RV IS-1 2.08/1.00 1.0 0.5 New Interstage-1 IS-2 1.00/1.00 0.5 0.25 New Interstage-2The PSLV first stage is ruled out, as it is too large and would need stationary launch platform and thus be vulnerable to first strike. The two inter-stages are needed and these require ground tests to qualify them for the design flight structural loads and separation. A stretched version of the PS-3 could be developed and ground tested. None of these needs flight qualification. Only integration flight tests are needed.Indian constraints are the following: - Shakti-1 yield requires great accuracy. This implies the Agni RV design has to be retained. - Overt testing of long range vehicles will bring great pressure on India. But new world disorder requires exploring options. - Any new vehicle will have to fit the envelope of the A-II rail launcher capability- length ~ 20m and weight ~28 tonnes. This way existing infrastructure should be usable.From the above data the following vehicles can be configured with .5t payload. Name Diameter Length (m) Weight (t) Comments P-1 2.08 18.1 22.75 PS-3, IS-1,PS-3, IS-2, AII-2, RV P-2 2.08 21.6 31.25 PS-3-S, IS-1, PS-3, IS-2, AII-2,RV P-3 2.08 17.6 27.75 PS-3, IS-1, PS-3, IS-1, PS-3, RV A-3 1.00 25.6 19.5 SLV-1, IS-1, AII-2, I/S, AII-2, RV A-II 1.00 20.6 15.5 SLV-1, IS-1, AII-2, RV P/A-1 2.08 24.6 24.5 PS-3, IS-1, SLV-1, IS-2, AII-2, RVThese configurations have to be calculated and the final RV speed determined. The goal should be to identify those configurations that can provide ~7.0 km/sec. The preferred choice would be the combinations, which have AII-2 and RV as these do not need flight separation tests. By inspection P-1, P-2 and P/A-1 are viable candidates for further investigation. P-3 would need flight separation tests. P-1 has the added advantage of having all the stages already flight qualified. Moreover as it uses two PS-3 stages it will have reduced unit costs (affordable) and saves on propellant costs. The length and weight summaries are attractive. Also if the weights can be more realistic, a better picture would emerge. For example the inert weights and the I/S weights could be reduced to achieve longer range.NOTE: These are notional concepts and need to be analyzed to weed out the sub-optimal configurations and calculate the terminal speed. Due to the current stalemate in India (political etc.) I thought my idle mind could speculate on how to proceed from A -> S. ( I don’t want my Telugu friends to remind me of the proverb about the idle barber etc...) As India is busy politicking, I thought it would be interesting for the forum to discuss some worthwhile concepts instead of lazy commentaries. --------- Shiv, did you get a chance to talk to the IIM guy?

Peeyoosh · Post by **Peeyoosh** » 25 Oct 1999 13:42

RamannaOne question - why a payload of 0.5 t. Given that delivery vehicle is key, and we are unlikely to be able to test to satisfaction the warhead design should be large to compensate for limited accuracy.Add the fact that due to paucity of fissile material we may have to use dirty weapons which have a higher weight.As far as I know satifactory thermonulear designs in the mid 60s were of 5 ton weight (not sure), and the current crop of Agni delivery systems is of one ton delivery capability.why do you suggest a 0.5 t delivery capability? why not try for a 1 ton delivey design capability?PC

ramana · Post by **ramana** » 25 Oct 1999 22:42

The heavier payload you suggest would require larger vehicle which would not fit the existing infrastructure. Please read my assumptions. The idea is to maximise existing infrastructure to make it affordable. Not reinvent new stuff which could be expensive.Half ton is quite heavy and reasonable estimate for the Indian level of technology. Chellany in his many fuliminations has said the POK-1 was 800kg and that was plain vanilla version. An improved version was the S-2 which was similar technology but a/c delivered. I assume it was close to 500 kg as the IAF has experience in operating these class of dumb bombs- aerodynamics etc.Refer to DRDO Techfocus mag which talks of 500kg HSLD dumb bombs. I hence assumed S-1 is similar in weight to this. I could be totally of base that is why I had the caveat in the conclusion about need to have further refinements to be explored. Any way I would like aero gurus to look at these and tell me what works and what doesnt.

Calvin · Post by **Calvin** » 26 Oct 1999 03:11

The Indian nuclear program is quite an advanced program, if we are to believe RC -- and there is no evidence (wallace nothwithstanding) why we should not.The fusion-boosted-fission primary enables us to make TN weapons considerably lighter than the true-first generation weapons that the superpowers first deployed.This is probably why the 1 ton to 0.5 ton range is pretty good. Also, the A-II's specified range is with a 1000 kg warhead, not 500 kg.

P Smith · Post by **P Smith** » 27 Oct 1999 06:00

No problem Ramana. Try <A HREF="http://209.207.236.112/rlg/980327-range.htm" TARGET=_blank>http://209.207.236.112/rlg/980327-range.htm</A> for a detailed intro. on this subject. For those trying out the equations in this paper, what do you think about eqns. 3 & 4?

ramana · Post by **ramana** » 27 Oct 1999 09:05

psmith Thanks for the Garwin article. I have used some thing like that for sizing calcs in this thread. Will see what his eqns. show.Eqn 3& 4 are called pocket rocket eqns and are used often for sizing calcs. Where are you located? send me an e-mail. ramana

Arun_S · Post by **Arun_S** » 28 Oct 1999 10:26

Can someone now use the equation to get prlim range enhancement estimates for Agni-II by staging the Second rocket into two ?Appriciate your initiative. I would have done it except that I am on the road (in Japan).The next step would be be look at Ramana's list for viable combinations to fit ICBM role.Cheers -Arun[This message has been edited by Arun_S (edited 27-10-1999).]

Arun_S · Post by **Arun_S** » 01 Nov 1999 08:55

I have just finished writing a prototype program to compute missile trajectory. I need to generalize it for muti-stage rocket.As against the simpler analytic equations, this S/W currently accounts for effect of gravity on true launch lift, as well as the effect of steady boost phase as against simplistic instantantanious impulse.It does not yet account for air drag, centifugal force due to curved earth surface, as well as the glide potential of the re-entry vehicle. Just wait for the first prilim results for various ICBM configns in next few days.My first test run using first stage of Agni(10-Ton stage) and 1500Kg re-entry module, gave the following results:Time Velocity Hight Horiz-Distance (Sec) (Km/sec) (Km) (Km) 53second --- 3.03km/sec --- 36.8Km --- 50.8Km -First Stage burnout 244sec --- 2.385Km/sec --- 213.6Km --- 506Km -Apoogee 452sec --- 3.141Km/sec --- 0Km --- 1003Km -On TargetCheers -Arun

Arun_S · Post by **Arun_S** » 02 Nov 1999 12:19

OK. Bare with me for relatively modest incremental progress. Please note that I am not a aerospace engineer by profession, just that I have some credible intertial navigation experience.So now I have the 2 stage rocket ballistic software (prototype) ready. I am yet to factor in for air drag, centrifugal force due to curved earth surface, as well as shallow glide potential of the re-entry vehicle. The last two factors can increase the range significantly.Putting in the Agni-II confign for Agni-II to validate it gives following:Following result is based on : Agni-II Stage1 : 10 Ton & 0.85 fuel mass fraction Agni-II Stage2 : 4 Ton & 0.85 fuel mass fraction RV + Payload(1000Kg) : 1500 Kg Time.... Velocity... Hight... Horiz-Distance (Sec)... (Km/sec)... (Km).... (Km) 53sec --- 1.68km/sec --- 19.4Km --- 33.4Km -First Stage burnout 75sec --- 4.07km/sec --- 54.3Km --- 82.2Km -Second Stage burnout 328sec --- 3.22Km/sec --- 368.9Km --- 900.9Km -Apogee 602sec --- 4.195Km/sec --- 0Km --- 1784Km -On TargetPlease note that once my model accounts for centrifugal force and shallow-glide on re-entry the range discrepancy (1784 Km against the announced 2000Km) would narrow. My gut feeling is that these two factor would easily provide ~300Km of additional range, and that would theoretically validate the announced range of 2000Km with 1000Kg payload. Following result is based on : RV + Payload(500Kg): 1000 Kg Time.... Velocity... Hight... Horiz-Distance (Sec)... (Km/sec)... (Km).... (Km) 53sec --- 1.78km/sec --- 20.9Km --- 34.9Km -First Stage burnout 75sec --- 4.64km/sec --- 59.9Km --- 87.8Km -Second Stage burnout 370sec --- 3.63Km/sec --- 486Km --- 1162Km -Apogee 684sec --- 4.762Km/sec --- 0Km --- 2302Km -On TargetAny comments or groan ?Cheers -Arun[This message has been edited by Arun_S (edited 02-11-1999).]

Arun_S · Post by **Arun_S** » 02 Nov 1999 14:50

OK, now I have factored in the effect of earth's rotation & centrifugal force, which tend to improve the range.I am yet to factor in for air drag, and shallow glide. For the time being I am assuming that these two opposite factors cancel out each others effect.Thus now the Agni-II confign simulation result as following:Agni-II Stage1 : 10 Ton & 0.85 fuel mass fraction Agni-II Stage2 : 4 Ton & 0.85 fuel mass fraction RV + Payload(1000Kg) : 1500 Kg Launch Direction is same as earth's rotation.Time.... Velocity... Hight... Horiz-Distance (Sec)... (Km/sec)... (Km).... (Km) 53sec --- 1.69km/sec --- 19.6Km --- 33.5Km --- First Stage burnout 75sec --- 4.09km/sec --- 54.9Km --- 82.2Km --- Second Stage burnout 399sec --- 3.22Km/sec --- 464.2Km --- 1129.7Km --- Apogee 744sec --- 4.193Km/sec --- 0Km --- 2242Km --- On TargetWith this, I am now ready to plug in for various rocket configns to see its ICBM performance potential.But before that I must first sleep tonight & go to work tomorrow.Anyone interested in my "Rocket Ballistics Calculator" prototype program ?Cheers - Arun S[This message has been edited by Arun_S (edited 02-11-1999).]

ramana · Post by **ramana** » 02 Nov 1999 22:38

Arun, Thanks for running the calcs. Bring a copy of the program and your documentation to the Nov 13 meet at Swagat. Yes I would like a copy.

Arun_S · Post by **Arun_S** » 02 Nov 1999 23:28

I would be glad to share the program. I am also looking forward to someone to volenteer to audit the calculation scheam.I need to add a confign GUI to the program so that user can specify parametrs for as many stages, without requiring to modify the code to initializ various parameters.As for modifification to support overlapping stages, I think that should'nt be difficult (like anything else in the S/W business), for the time being I guess it may have to wait a little longer. Of course you can modify the code to argument it if you like.The current code model does not use true 3D interial space model, but use a hybrid 2D model, which is adequate & accurate for the purpose. I.e. it can take care of missile as well as satallite launch. I got surpized by how rusty my physics is after so many ears of school. I had to brush up lots of basic physics and scamble for lots of books which I do not have anymore. Cheers -Arun

Arun_S · Post by **Arun_S** » 04 Nov 1999 15:02

OK. I have only run some basic trajectories. The priliminary result is that the best range is on A-3 configuration, and that all PSV-3 based configns (i.e. P-1,P-2,P-3) are inferior, mainly due to the lower thrust rating at launch. The better of the above give max speed of ~ 5km/sec and range of ~3500 to 4200 km.I guess to get to 7km/sec ICBM speed it is necessary to have a first stage with very high thrust so that the rocket can enter 45 degree trajectory inspite of the weight of initial launch weight.Details for each confign performence later.More I think about it, I think clustered / bootstrapped rocket confign around Agni-Stage-1 would yield desired result. Such clustering have been proven by ASLV flights. Let me think of some confign around it to see if it can yield ICBM missile.-Arun Sharma[This message has been edited by Arun_S (edited 04-11-1999).]

Arun_S · Post by **Arun_S** » 05 Nov 1999 00:35

>>What is the range of Agni-II with RV(500kg)+payload(500kg) factoring in rotational and centrifugal effects? Yes the rotational & centrifugal effects are accounted for. The program is still in my home computer, so I can not run it now to get the acutal figures. However the number that I recall for Agni-II with 1000Kg payload was 2150 Km. For 500Kg payload it was ~2700Km.>>Also, what is the error estimate for your simulation ?. A). The errors are mainly due to the assumption of drag (which tend to reduce range. I look forward to someone who can give me a simple model for drag estimation (a function of {altitude, speed & diameter & length}.) & re-entry glide potential (which tend to enhance range. I am incliend to believe that ~15-degree inclined re-entry at hypersonic speed is possible). Thus for the time being, I take the conservative estimate & say that these 2 effect cancelout.B). The other source/constrain is that individual rocket stages fire at a constant inclination w.r.t local horizon in space, for the duration of the stage firing. But I do not think this is a mjor issue.C) the third configuration aspect is the simulation interval. The defualt is 0.2 sec. But I have suggest 0.1 sec. One second simulation interval gave me once 5% variation. >>and what entry parameters are required? Parameters required are: Payload: (including RV deadweight) Number of Stages: Simulation Interval: For Each Stage the following:::: 1. Stage Name: 2. Stage ISP: 3. Stage Gross weight: 4. Stage fuel fraction: 5. Burn time: 6. Stage attitude (angle w.r.t. local Horizon) for the duration of the burn >> US midgetman.....Should also try for Prithvi, Nodong, Taepodong, Shaheen, M-11 etc. Could be very interestingYes indeed. If someone can get me the above confign info for these missiles, I can do it. Or better still for you to have my "Rocket Ballistic Sumiulator" and see and play with the result by changing payload & stage thrust angle. >> I am puzzled why A-3 will not give required range. Try out the configuration, to get a feel of the tradeoff between gross-weight & launch speed.There is so much more, but may be on later post.I have not yet made EXE excecutable yet of the program. Still running it in the VisualBasic devlopment environment ! Hope to make EXE this weekend.I am sure this would be useful for future discussions & it may be a good idea to put this program on Bharat Rakshak web site for download.. In the mean time I can give it to interetsed people during the BR-Forum BAY AREA meeting this 13-Nov. OR I can e-mail it to interested people, but e-mail address is a privacy issue, I do not want you to post your e-mail address on the BR forum. I welcome ideas on possibilities. Cheers -Arun[This message has been edited by Arun_S (edited 05-11-1999).]

Arun_S · Post by **Arun_S** » 05 Nov 1999 13:14

Interesting Agni-II range enhancement by staging the last stage. If the last stage is split into 2500 Kg & 1500 Kg segments (assuming 0.85 mass ratio can be retained on both new segments; which is quite a challange), then on a 500Kg payload the range enhancement is from 2948 Km(injection speed 4596 m/sec) to 3470Km (injection speed 4921 m/sec), an improvement of 17%.For 1000Kg payload the corresponding figures are 2169 Km(4036 m/s) and 2431 Km (4246 m/s), an improvement of 12%.

Sunil · Post by **Sunil** » 05 Nov 1999 22:45

How about a BR Technical Division

jayam · Post by **jayam** » 09 Nov 1999 01:44

Arun: Can you email me the code? Please let me know so that I will send you the email address.

Arun_S · Post by **Arun_S** » 09 Nov 1999 08:44

Yes, I will send the program to BR members requesting it. BUT currently I have developed it on VB 4.0 (very old), & run it on Windows-95 only. So let me test out it's inter-operability with Windows-98, before I send it & later get flooded with complain of run-time problem. Not to mention slow performance due to default use of varient datatype for numeric values core to the calculation. I would like to convert them to numeric datatypes for faster computations. I anticipate the program to be available for distribution in approx. 3 to 4 days.BR Admins: I would like to give the program to BR-website, and make sure the BR-credits showup every time it is used. I am not sure if the source code should be in public domian, that way BR credits can be easily removed. Any interest ?Cheers -Arun [This message has been edited by Arun_S (edited 08-11-1999).]

Arun_S · Post by **Arun_S** » 09 Nov 1999 13:17

>>>>Also, what is the error estimate for your simulation ?. On deeper thought, I realized there are 2 more error sources that I had overlooked, but now the software factors these 2 effects into account. The first effect is decrease in Graviatational field as the rocket climbs higher. Thus the instantaneous Gravitational field is G/(Radius_of_Earth + Altitude)^2. Thus in case of Agni-II the G is 9.8m/s2 on launch, but at its maximum altitude of ~698Km the G is reduced to only 7.95m/s2.The second factor is that as the altidue goes up, every 1 meter traversed horizontally actually transposes on earth a distance lesser then 1 meter. THis requires a correction of Radius_of_Earth/(Radius_of_Earth + Altitude). Thus the new "Rocket Ballistic Simulator" now yield the following for AGni-II confign:Agni-II Stage1 : 10 Ton & 0.85 fuel mass fraction Agni-II Stage2 : 4 Ton & 0.85 fuel mass fraction RV + Payload(1000Kg) : 1500 Kg Launch Direction is same as earth's rotation.Time.... Velocity... Hight... Horiz-Distance (Sec)... (Km/sec)... (Km).... (Km) 53sec --- 1.696Km/sec --- 19.4Km --- 32.9Km --- First Stage burnout 75sec --- 4.004km/sec --- 53.4Km --- 80.3Km --- Second Stage burnout 432sec --- 3.159Km/sec --- 481Km --- 1152Km --- Apogee 810sec --- 4.104Km/sec --- 0Km --- 2290Km --- On Target

RV + Payload(500Kg) : 1000 Kg Launch Direction is same as earth's rotation.Time.... Velocity... Hight... Horiz-Distance (Sec)... (Km/sec)... (Km).... (Km) 53sec --- 1.799Km/sec --- 20.8Km --- 34.4Km --- First Stage burnout 75sec --- 4.555km/sec --- 58.8Km --- 85.6Km --- Second Stage burnout 541sec --- 3.550Km/sec --- 698Km --- 1624Km --- Apogee 1027sec --- 4.646Km/sec --- 0Km --- 3232Km --- On Target

I can not think of any other sources of error, except for the before mentioned atmospheric friction and re-entry glide potential.Cheers -Arun Sharma

Ramanujan · Post by **Ramanujan** » 10 Nov 1999 00:09

arun,i wud appreciate if you can quote references that you used for formulation of equations in your code.thanx

Arun_S · Post by **Arun_S** » 10 Nov 1999 00:41

As I suggested earlier, I welcome someone to audit the algorithm that I have used. Any volunteers? Though it is about Rockets, but the computation is simple physics & not true "Rocket Science" !As for references, most of it from my (very old: 1985) M.Tech (IIT-Delhi) thesis titled "Design & Development of Fault-Tolerant Multi-Processor computer system for Intertial Navigation System". Incidentally those days I had access to the initial documents for PSLV's Strap-down Interial Navigation System. But my project work was more related to Fault Tolarent Architecture & INS for combat planes.Cheers -Arun

Arun_S · Post by **Arun_S** » 10 Nov 1999 00:49

I can now send by e-mail the software to those who had requested for it, on "As Is" basis.Please note that I have tested on Windows-95, 98 & NT-4.0 only. Copy the two files to a directory and run the "Rocket Calculator Version 2.1.EXE". Do not forget to copy the DLL file to the same directory.Try it & have fun. Let me know what you think of it ?Cheers -Arun Sharma[This message has been edited by Arun_S (edited 09-11-1999).]

Bharat Rakshak

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