MEMORANDUM FOR DR" FLAX 

SUBJECT: TAGBOARD 

fT ( 

17 Nove:moor 1961 

Mr .. Bill Fl$her informally requested the answers 

to four qnest1()us eOl1cerni1ll[ TAGS:OARD" It is understood 

that the questions would. be raised by BOB representative 

at the EXCOM meeting 11 NO·V'fIlmber .. 

In addition, Dr. Steininger,. also informally, submitted two questionsf same subject and apP&l"ently to be 

discussed at the same time .. 

I thought it appropriate to furnish you the answers 

and at your discretion pass the anSWers to the concerned 

personnel at the EXCOM meeting. 

Attachment 

Tag Questions 

& Answers 

FRANK W. HARTLEY, JR. 

Colonel, USAF 

Director, Program D 

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1.. Wha~ type of .guidpce syete. is\1sed in TAGOOARD? 

AlfS'QR: Q3$OJ') Iaert1al liavigat1on8ysta (INS) 

designed and praoueed by lI .... li, sub to. LAC.. The 390 is 

installed in. theD-21B qd theB52" Add·! t.1onally , the 

BSJis are equippe(l with Stella.r Traekers 04B330K) which 

update the INS continuously ~ TIle 390 was prev ionsly in 

the D-21 and mod:i:fled sli,btly to operate in the D2lB. 

The flight test data is extensive and in fact, this system has proven to' be very reliable and accurate .. 

2. Whell is the last input or \t1}da te to be made? 

ANSWER: The Stellar is eonstantly updatini the 

852 and D-21B INS dUriDg mated flight. Just prior to 

launcbof the D-21B th-e Stellar will update the D-SUB 

INS to a bounded error of 1 .. '1 D .. 

3" What is the CEP at end of 1)...218 free fligbt? 

ANSWER: The design specifieation maximum errOl'" of 

the 390 1s 1 .. 5 mi per hour of fl.ight; therefore, for the 

progl"ammed 3000 Nlf 1>-218 range the max1mum error is estimated to be 1.5 NM X 1.5 hours: 2.25 NM ~ 1.7 bounded 

error at launch -3 .. 95 NM_ Tb.is maximum error 1s based 

on a short mated flight. For an example, see attached 

chart, f()l~ a twelve bour mated flight plus 1 .f. 30 hour 

free flight, we can expect a maximum errol" of 4.25 NY. In 

actual conditions, flight test b.ist(n;·y reveals that we are 

achieving approximately 50S better than specifications. This performance is considered excellent when the camera 

coverage of 28 NM. 1s conSidered. 

4. Does the INS correct in flight? 

ANSWER: The INS is updated by the Stellar Tracker 

only during mated flight. 

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1. What 1$ th~ Radar Cross 8$ctioll of TAGBOARD? 

AlllSaR~ 'rhe attaehed charts (12 attd 3) are for your l"~v1$<'W and US$'.. The TAGBOARD Radar Cr08s Section was 

broken out $epa.rately to avoid a c&mpar:b!Jon. 

2. What 1·$ th$ vulneJ'ab111ty of TAGBOARD as compared to 

OXC!RTat 50,000 it and higher? 

MfSWD~ The attacb~d charts ('4 and 5) show the miss 

{11$tance data as just l""ently computed on the Electr~mic 

Wa.rfare Euviron ... ntt.l Stmulator at General Dynamics, Ft. 

WOI'tn.. As you rea-las, m1ss 4.istanee 1s only one factol' 

of vtllnar~bility; hOWevel~, the complete vulnerability study has not yet been completed. 

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RADAR CROSS SECTION (RCS) 

The RCS simulated for three systems is identified 

below. For each system the ReS was varied with system 

penetration toward the site. Guideline missile launch 

ranges"were 36, 34, 32 and 30 MM. Launch range is 

slant range from Fan Song B site-to-target. Offset 

ranges (i.e., cross range at which the target penetrated 

the Fan Song B site area) were 1, 4: and 8 NM. 

SYSTEM 

IDENTIFICATION 

TAGBOARD 

SR-71 

OXCART 

APPROXIMATE 

a-BAND RCS 

I 

I 

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RADAR CROSS SECTION (RCS) 

The ReS simulated for the TAGBOARD system is 

shown below. The RCS was varied with system penetration toward th~ site. Guideline missile launch 

ranges were 36, 34, 32 aud 30 NM. Launch range is 

slant range from Fan Song B s1te-to-target. Offset 

ranges (i.e. cross range at which the target penetrated 

the Fan Song B site area) were 1, 4 and 8 NMa 

SYSTEM • nf<:N'I'T1l' Tf"ATTt1l\T 

TAGBOARD 

APPROXIMATE 

S-BAND RCS -

-

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