Kiker, J. W.

English

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TAI_DiNi3 A_D IMPACT '_V_'m_+°
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Manned spa.cecra_ wi-th _ bhm¢, liffting body confi_rat:Lon, such _s the
Mel"ctll+y_ '3e_lZ[: _Ind A;OIIO spaceoraft_ reql/ire a_ 5t_xl]i_ry ]anding _ystem
for suocessf_tl eomp.]etior_, of the mission and s_fe return of the cre,_, Land-
ing ,._ystems with widely w_ried performance ch._raeter_sties _re presently
:tvailab'te or in varic_Is _t'-,_ge';of' development. The primary consideration in
select.ion of _,+]::_dir-g _:'ystem _'or a particular space vebic'}e and mlssion "iz
crew s_foty, or _;y,-tem t,ali+%bi]it;.,,.Beyond re] lability, the mission term_.n_
!'!ight plur: wi_,l d_ctate the require_'J 'landing system perforraance. For ex_mp'_£,
il+ the mo]'%u_] mi,;sion termin_,t_s with impact in water or 8,n unprepared ],and
,_urfacc, a near vertica.i tormi_a[ descent is prefersb]e, landing on --_prepared
_and s_u-f_c:e., on the other l,_md, 3e'_(isit;;_)f to un aircraft type i']ared _a_d-
• , ' "[" runw:_ control then becomes necessary to ins%relng, A degree c[' _;]_{,_g or
]andlng on a prepared surface. (This does not necessarily mean that even with
r,_nge capability the i::,e;;,tme hod o_ i._md:ini_, is horizontal ]y). _e impact shoe;",
:_tt,_nu_tion cequire.me.nt,';are "+;ik,..,w:[:_e _,_'cdicated on _he type "Landing :;ystem
selected. ]3_aJee]]y imp_._ct :'yste_t!ze'm be broken down intotwo require,/ ty;,.:_,:;;
one for }dgh vert_:+'u] r_.]t+_ o V _!escent w'lth wtlr,A drift considerations, the othe V
for 3o%,cr w, rt[ca] r,_,teOF de,_;c_._t_+lth a ho_'izont:._] w+]ocity. Basic consid-
ez':r_ons such _,_ w<-Igh't, voIt_ae_ depq oyment_ st_bil_ty, co!+tro],_ redundancy,
.%nd/or emerjeuey escape., 'm_ comp'+c.+xity must a],:o "be evaluated in selecting a,
la.nd_ng system for a pa_Ci?u]ar vehicle.
APOI,LO
3. T_:e Apo_3o is one c,f the two Manncd '" " :' " '+,_p._ce,,r,_ftCenter spacecraft pre::,
ently _nder deve._opment. The Apollo ]?,riding,zy_otem requirements are gener,_._!y
_t5 fOl IO_.
a. A high degree of rc_iability, and a system t_zt can be used under'
a_?+ f'[i_ht conditions for earth _ndlng requirements. This includes no;+-
ma+] reentry, n_x:hutun d,yna2}ic pressure escape_ and pad abort.
b, Stabi]ize._ the Con_,nd Module during post-entry descent and re-
duces the vel+tica] ]:_nding velocity to _O'/sec at 5000' _].tltude, Horff-
zont&] dr.[_t _[ue to wiua not to exceed 30 knotL;.
c. Reduce:; impact accelerations such that neither the Co,%_.md Mo+]u,c
;_t_tcturc or f_ot+}tlon is impelred. Fu_"the_."attenuations to be by crew
se,_,t shock _tter',uation devices.
d. _y:_tem to be comp,_tib]_÷: with t_te _Jse of u, moderate L/D tez'min_,
1.anding syste_ such as a Parawing (this requirement w_s }ater deleted ct_,tc
May '/,3, 1.94,?) •
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https://ntrs.nasa.gov/search.jsp?R=19730061704 2020-03-17T13:47:45+00:00Z
'. The system selection by }a_C to most nearly i'it the established re-
,Tui_'cments is as fo7 lows:
a. Descent System
(i) System selection criteria
The advantages and disadvantages for the selection of a
cluster oi" three parachutes are shown in slide I. The advanta-
ge_ oi" a parachute c]uster are as follows: it is within the
state-of'-the-art, prow[des excel ]ent pendulum stabi]ity, pro-
vides a high degree of" re]iabi]ity, very. low weight and vo]ume,
is an easy way o]' obtaining redundancy, and it is a pas:;ive
sy._tem. The only major disadvantages of a c]uster is that it
is no_m_aneuw_rab]e. For Apo]]o, the use of a single parachute
would ],ave requirecl that it have a diameter of approximately
]2['. Present state-of-the-art in parachutes have determined
te<_t paraehute_ of this size are difficult to fabricate. Large
parachutes a]so present a packing and insta]]ation problem. To
provide redundancy, this would have a]so resulted in a heavier
landing system and requiring more volume than the selected
<: I t,lDl_._.L" a-.'ra_gement.
(2) Dop] oymer_t sequence
Slides 2 and _ depict the deployment sequence for the Apollo
earth ]anding system. The sequence oJ' events are the aft section
of the Command Module i:_ jettisoned, a 13' diameter drogue chute
is mortar deployed, the drogue chute is jettisoned at a prede-
termined altitude and the three main parachutes are deployed by
mortar deploying pilot parachutes. The pilot parachutes then in
turn pull the extraction chutes which deploy the main parachutes.
The main parachutes are reefed for a period of six seconds prior
to full inflation.
(3) Test program
The Apollo earth _anding system wil] be tested at E1 Centro,
CaSifornia. The test will be conducted utilizing a B-66, C-_30
and C-133A aircraft. The B-66 aircraft will be utilized in test-
ing the drogue parachutes. The C-_30 and 133Awi11 be utilized
in testing the single main parachute and the complete earth land-
ing system. The present status of the Apollo test program is
that 3 tests have been conducted on a single 88' di_neter para-
chute to establish optimtun parachute reefing parameters. It is
anticipated that approximately 70 tests will be required for the
development and qualification of the earth landing system. The
parachute system #'Sight envelope is probably best described at
this point.
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Graph No. ! gives the drog_J.e par-'_chute design envelope an_,
is self explanatory. Normal drogue parachute deployment is
initiated at 2!),000 feet. At a dynamic pressure of 140 psf, the
Connnand Module is stabilized with the drogue chute descending to
an __n_"_ _ ]5.nnn._ fee!, _here +h_.....main chute's deployment.
sequence is initiated at _ dynamic pressure of 64 psf. The
drogue parachute has been designed to be capable of deployment
at a q of 2]0 psf' and at any altitude from _500 ft to 2_5,000 ft.
In the case of "pad abort", the drogue chute can also be deployed
through this ss21e a]tltude range at a minimum dynamic pressure
of ]0 psY. Gr'_ph _o. 2 shows the design envelope of the main
p_{rachutes. The main parachutes have been designed to be capaL_e
of being flep]oyed at a maximum dynamic pressure o_" 96 psf" at any
altitude From _500 to ]5,000 ft _nd likewise, they are capable off
being deployed at a minimum dynamic pressure of ]0 psf. This !(rw
dyn_[c pressure could be encountered in the case of' a "pad abort".
There are some problem areas with this earth landing system which
:_re anticipated although are not considered to be major obstacles
to overcome. These problem areas are (]) the mortar deploying of
01"I three .main i)e.rachl_'tesand (2) the effects of a ma].lh/nction of
a single parachute on the other two parachutes.
b. Impact System
(]) System description
Slide ],depicts the capsule impact attenuation sysZem. This
consists el' G air oil struts for vertical attenuation and 8 a!um-
intun honeycomb doub]e acting struts for horizontal attenuation.
The oil use4. in the ttir oil strut is OranJte 85]5. The total
stroke of the air oil strut Is approximately ]2". The aluminum
honeycomb strut has a stroke of approximately 4".
Slide 4 shows the attenuation system used for the individual
crew seats. This consists of 4 honeycomb shock struts for verti-
cal loads, two honeycomb struts for horizontal loads and two honey-
comb struts across the chest. The aluminum honeycomb struts are
designed to control the "g" buildup.
(2) Design consideration
The known safe human tolerances are shown on graph no. 5.
This impact attenuation system is designed for the following nomi-
nal conditions which are within the safe zone.
3 chutes out - vertical rate of descent 25 fps
horizontal rate of drift 30 fps
Max slope of' 5° at impact
Allows 20 g':s vertically; ]0 g'_ horizontally at 250
g, ;/second.
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Design emergency conditions:
2 chutes vertica_ rate of descent 30 fps
horizontal rate of drift 50 :[_0s
Max slope of ]5° at impact
Allows 40 g's vertlea]]y; )_0 g's horizontally
(3) Test progra_n
Pre_ent plans call for impact tests utilizing a full scale
boilerpl:ate Co:_nand Module. These tests will be conducted at
NAA on a test rig presently under construction. This rig will
not be available untLl probably January l, 1963.
To re_luce the number of bo-il_]ate impact te;_ts, a l/4
ela:_tically scaled model progrma wi]]_ soon s_tart at LRC. This
model has a _cale strength heat shield and strut attenuation
::_ystem. This model will be tested on sand, hard surface, and
water to determine the dynsJnics and acceleration loads.
The dii_ficuIty wdth an active system is the somewhat tower
reliability because of the operation of addTitional mechanisms
which have to be employed in releasing the heat shield.
Another problem would be the necessity to choose between
having a depiloycd or nondep]oyed hnpact system when landing _n
water. For in,stance_ with the proposed kpo]]o system, there is
a gre'tt possibility th,_t the heat shield, if deployed, may dig
into the water causing severe capsule motions.
CURI@_T ADVAI_CED LANDING SYSTEMS STUDI[S
I. At this point some of the programs which are presently being conducted
by M_-_nned Spacecra_._ Center in support of both future spacecraft and Apollo
should be described.
2. The first program is the development of a parachute know_ as the Glib]e-
sail. This progr_n _s being accomplished by Northrop Ventura and has as a
primary objective, the development of a gl'iding parachute havlng, an I,/D of
approximately 0.7 to I and which can also be controlled dire_tior/_lly.
3. It i'_ real;ized that the performance goals for a par;1.eh_te of' th_s na-
ture would not provide a range capability _but would allow avoidance of local
obstacles ,_nd partially alleviate the impact attenuation problem by bein_ able
to overcome wind drift. The present status of this program is as fol low;:: A
wind tunnel test pro_r_m has been completed by Ames Research Center using l_5'
di_uneler parac_n_tes in the 40' x 80' wind tunnel; the results of the wind tunnel
progr_m hrzve been verified by 4.rop tests of' both 65' diameter single an_ j chute
-b-
......... , ,_............ a, p_.t.zmz,az-j drop b_mt data have _eri2iec[ the
,' :_ t',:::. - L'.: :u,t':: _:h'Lch indicated a maxim_m_ T,/D of-_,pprox#mat, e7y .5 to .7.
2!'[.L: j :o,::','._1 is S,.ltC,iu_e,,i f'_r templetion in early October.
it_ i,-t,_:;_l]_ I" :,t_t-jjrt," For ,]e::cont ,,%rid _ncorT)ora.ting a l,'_lld:[lJ!-,. rocl-ct l"c.r .'Jt%o.<'ur+,-
tJc_Lt. Air <lro!_ t;<' ;t,'.] el' tlic D'U';cehutc# without the ]:±ndtnb, roct,',etj and stem,tic
f[l'iih';,; OI' tl7e ]'o+,k<'t snorer Jh'lVO bcol'l conip].el_ed. The re:'u]t<B o;t' these test,_
h,.,ve:J'ow_ the fe,_s[l_Llity of" ,':,.control ]able parachute retro rocket eurth ].,:m_-
!,,,;W;::_cm; th_-r<-l'orc, '-_;r.-Iropt,o:_ts of' tb,; compTeto system utiqizing_ a C-I].[
: irVi',m," wil'_ I,_*,',.,L_i.ucte,,lu.t liou:;ton in the. _ca,r futm.'e.
'.,, it tlcird t_l'o_:t,ul_ i:; the dcvelol._m_:nt of _t dc}_loymcnt t<:cill_J']oe f'or the
]':_.i.'a_:]i.1cr. A rcv{,,v, of ,,il l;l_ework bci.n,,,iacc'ompl.i,;h_;(]on Par'_gl:iders, :_n-
d i,'.',tcd_,_r'4,1hl<_' d<_l>]o.vm_r_tw.'u.:one of t,hc mu,]or .prd[/lem:',to be solved before
it co_fid be _::..,i-_:','m <'_rt]_ l',_!In!,::.;y-i_t,t'm.A joint i;z'o[,r;mlwith T,RC has been
1n.itlL_ted to invc:_t],<',te r,,_r:,,_.i::_:d_:plo.yment. T_,mglcy will concb_ct the te:_t:;
truing tl_e 19' tr:_,;;ol,[c, wunn'l _til izh_i,, c-l,.r,_tically :rod. d,/_t,xnic, r'_-tYle mOdel.:D.
It is "eel ieved thi s l>:ro,"c,u,,l cam comtri but;,+- ,;]_-[,.<.li.X'Jca,ntl.v to ,]evel op{r4_ a sat, is-
:'(iotoL 7 m_,_uis el' },'-_r_7{r] ]<h;r dcpGo;v;rl(,nt.
k
];1JTURE _'RO(] [tAMS
i. The T;tud'i.rG,: ,tl'l(] !ll_i;:'_<-.'t <q.v:;tcm:" L;,:ct[on h,'tve ;J, n_bcr of f%_ture progr,t:/ns
olanrl,_d whic.l: etA, mr v_r/o_z:_ : _'__;,t-. theft ur(; :-_ot lu'e:xe_d;I.v being inve:-_t!g,,_ted.
These p;'o_-:r'_ns <ire: -,
:__. 'I'hc development o1' a e.hutc with etn L,/D i_rr,at(,r thu, n on,,:.
b, The dow;7otmieut o:I' "_ ]a.r, ding> rocket f'or :._1;-tenu:,t[ono1' ADo] Io slze
,.'. The devr_lo])mtmt o1' l,"_rgc sin_Tc; p:+rr.J.c_hu%e:; c.u.p,<._l,7e o_? reco_c:rJng
_paceer_c['t wei6b:[ng :0,000 pounds.
d. bcvel o[)mcrlt of' dro_n_c par:_.c.hutes in size.'; ,'.ippro×.inlat,_I#ill to ]d'
in dJnallc.ter whic}l ctul b(: deployed '.;tt Mac_i nttmbers tip to ;7 at an a,ltit_xde
oi" <:,0, OOO -f'eet.
e. I{,w_stl{mte th<" t'e:,c;ibility of' e.jection sea,t,<; .For sp:,.c-erzral't.
f. The d<,velopment of <_rlaltitude sensor to be usc:d in conjunction
with the funding i'ockcto
_. The ,,.;tuciyof soils as they apply to impact u.ttem_a,tioi_ :uT,l it','
effect on the _l.ynam/ec,o-['the spaeecraf%.
h. The dcvclopment o:f" a rotor ]<md:irig system.
. ihe progr_s ore readily _nder_'tood, however, a few comments e,re y_er-
__:_± _'_ia%ive to the "ast program pertaining to rotors.
j. LRC as well as the other NASA centers have programs investigating every
f_icet oJ Zhe parawing and the paracbmie. Little or nothh_g hms been accomplished
on rotors, however, theoretica'[ly, from a performance standpoint_ the rotor sys-
ten: can provide a touchdown capability of near 0 vertical and horizontal ve]oci.ty.
It is intended that this program be accomplished as a Joint effort with the _4nes
Pesearch Center.
RECOMMENDATIONS
I. It is interesting to r_ote the n_ber of NASA centers which are represem-
ted t_nd the genera] interest w%lich is now being shown in landing systems. The
problem of developing any earth landing system is a mammoth one and requires the
complete cooperation of all the NASA organizations. It appears that a landing
system co_,littee should be established with a possible member from each center
and headed by a representative from NASA Headquarters. In this manner, duplica-
tion of effort could be avoided. This, in turn, would reduce new landing system
development time and cost.
?. I do not know what is the best landing system. It is certain that para-
<\-" chutes for the time being are the most reliable and probably the best known. There
is conoider_b]e e_'fort being expended in the development of the parawing, however,
NASA needs to look toward the future and develop some other system that w_1]d over-
come the deficiencies of the paraw_ng and the parachute. The selection of such a
system probably could best be acco_]ished by this p_oposed committee.
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Apollo landing system concepts

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