Hydraulic support apparatus for dynamic testing of space vehicles under near-free flight condition

Vonpragenau, G. L.

English

NASA Technical Reports Server

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON. D.C. 20546 
REPLY TO 
ATTN OF: GP 
FROM: 
October 16, 1970 
~ ~ ~ / ~ c i e n t i f i c  & Technical Information Divis ion 
Attent ion:  M i s s  Winnie M. Morgan 
~ ~ / ~ f f i c e  of A s s i s t a n t  General 
Counsel f o r  Pa ten t  Matters 
SUBJECT: Announcement of NASA-Owned 
U,S. Pa ten t s  i n  STAR 
I n  accordance wi th  t h e  procedures contained i n  t h e  Code GP 
t o  Code US1 memorandum on t h i s  s u b j e c t ,  dated June 8, 1970, 
t h e  a t tached NASA-owned U,S. p a t e n t  i s  being forwarded f o r  
a b s t r a c t i n g  and announcement i n  NASA STAR. 
The following information i s  provided: 
U.S. Pa ten t  No. 
Corporate Source : Marshall Space F l i q h t  Center 
supplementary 
Corporate Source 
NASA Pa ten t  Case No. : XMF-03248 
Gayle Parker  
Enclosure : 
Copy of Pa ten t  
NASA-HQ 
https://ntrs.nasa.gov/search.jsp?R=19710001130 2020-03-17T02:27:47+00:00Z
March 28, 1967 G. L. VON PRAGENAU 3,310,980 
HYDRAULIC SUPPORT FOR DYNAMIC TESTING 
Filed June 24, 1954 4 Sheets-Sheet 1 
#*' . -7 J - 
" w i t  */a$ 4.5 4 
FIG. I 
INVENTOR 
GEORGE LANDWEHR VON PRAGENAU 
ATTORNEYS 
March 28, 1967 G. L. VON PRAGENAU 3,3 10,980 
HYDRAULIC SUPPORT FOR DYNAMIC TESTING 
Filed June 24, 1964 4 Sheets-Sheet 2 
INVENTOR 
GEORGE LANDWEHR VON PRAGENAU 
March 28, 1967 G. L. VON PRAGENAU 3,3 410,980 
HYDRAULIC SUPPORT FOR DYNAMIC TESTING 
Filed June 24, 1964 4 Sheets-Sheet 3 
FIG.  3 
INVENTOR 
GEORGE LANDWEHR VON PRAGENAU. 
c 
"a,, 4 
AT TORNEVS 
March 28, 11967 G. e. VON PRAGENAU 3,3 10,988 
HYDRAULIC SUPPORT FOR DYNAMIC TESTING 
F i l e d  June 24, 1964 4 Sheets-Sheet 4 
INVENTOR. 
GEORGE LANDWEHR VON PRAGENAU 
ATTORNEYS 
United States Patent Office 3,310,980 Patented RhIar, 28, 1967 
B 2 
sunoorts of FIGURE I coupled to a shaker, the hydraulic 
3,31@,98@ 
mDRAULIC SWPCPRT FOR DYNAMIC mBTEING 
George Landwehr von Pragenau, HantsviFEe, Ala., as- 
signor to the United States aP America as represented 
by the Administrator of the Ibia~ona1 Aeronautics and 
Space Administration 
Piled June 24,1964, Ser. No. 377,780 
3 Claims. (C1. 73-116) 
The invention described herein may be manufactured 
and used by or for the Goverrment of the United States 
of America without the payment of any royalties thereon 
or therefor. 
This invention relates to  a support for the dynamic 
testing of space vehicles and the like under substantially 
free flight conditions. 
An essential element in the design of large rocket ve- 
hicles is their dynamic characteristics under free flight. 
It is the dynamic characteristics which help to determine 
the composition of its control system, the design of its 
body structure, and finally the flight trajectory of the ve- 
hicle itself. 
Unfortunately, the prediction of realistic vehicle dy- 
namic data is very difficult and often impossible through 
the use of theoretical analysis. Therefore, resort has 
recently been hied toward suspending the vehicle by a 
cable and shaking it to determine its dynamic character- 
istics. The data obtained, however, from this type sus- 
pension system is influenced by the suspension point forces 
and the resonant frequencies of the cables of the sup- 
port system. These influences are extremely nonlinear 
and difficult to account for in the analysis of the test 
results. 
Also, the cable suspension system does not mate easily 
with test objects such as space vehicles, spacecrafts, and 
aircraft, because these objects normally have provisions 
to sit on the ground or on booster stages when not in 
free flight. Usually, special adagters have to be built 
to suspend these objects and these adapters disturb the 
mass distribution of the objects. 
Accordingly, it is an object of this inyention to pro- 
vide a support for a test vehicle which approaches free 
flight conditions. 
Another object is to provide a hydraulic support for thc 
full scale testing of a vehicle about any axis and in any 
direction within a certain range. 
Other objects, uses, and advantages of the present in- 
vention will become apparent as the description proceeds. 
Briefly stated, the apparatus for supporting the test 
vehicle has a vertically floating piston with substantially 
frictionless means for regulating its oscillatory motion. 
Upon the piston lies self-adjusting, virtnally frictionless 
bearings which transmit the weight of the test vehicle 
to the piston. Thus, the floating piston allcws for any 
vertical motion of the test vehicle and the sell-adjmting 
bearings allows for any horizontal translational and/or 
rotational motion. 
This will be more readily understood by the following 
detailed description when taken together with the ac- 
companyilig drawings in which : 
FIGURE 1 is an elevational view of a test vehicle 
supported upon the hydraulic supports of the present in- 
vention; 
FIGURE 2 is an elevational view showing one of the 
- - 
lines removed for clarity; 
FIGURE 3 is a detailed elevational cross-sectional 
view of one of the hydraulic supports of FIGURE 3 ;  
FIGURE 4 is an enlarged disassembled perspective 
view of the self-adjusting bearing.; of the support of 
FIGURE 1; and 
FIGURE 5 is a partial elevational cross-sectional view 
of one of the hydraulic supports of FIGURE 1 with 
portions broken away to reveal the piston bearings. 
Refeming now to FIGURE 1 which illustrates a test 
vehicle 11 supported upon self-adjusting hydraulic sup- 
ports 1 3  of the present invention within a structural 
framework tower 15. As illustrated, four hydraulic sup- 
ports 13  are symmetrica~iy spaced about the aft end of 
the test vehicle B 1  exemplified by a large mulli-stage 
rocket. 
Each hydraulic support 13, shown best in FIGURES 
2 and 3, functions inde,aendenlly of the other supporta 
83, and sits upon a foulldation base 17. 
The hydraulic support 13, essentially coi~prises a self- 
adjusting, hydrostatic bearing arrangement 19 supported 
upon a vertically floating piston 21. 
The pisron 21 reacts the same as a vertical spring be- 
cause of its unique cylinder ring and oil-coixpresriom 
chamber arrangement 23 described in detail hereinafter. 
Two ring bearings 25 and 27 which are supported by 
stanchions 29 g~lide the piston 21 and assure rts top sur- 
face is horizontal. The ring bearings 25 and 2 h r e  the 
hydrostatic type and thus operate in a subsiantially fric- 
tionless manner. 
The self-adjusting bearings 19 are composed of an 
upper and a lower bearing 31 and 33, respectiiiely, havrng 
mating spherical convex and concave surfaces 35 and 37, 
respectively, as illustrated by FIGURES 3 and 4. Thus, 
it is apparent that the vehicle 11 ma37 be tilted about its 
transverse axis and the pos~tion of the Z o ~ e r  bearing 
33 is not distnrbed because of the zbillty of t!~e upper 
or pivot bearing 31 to slide and adjust within the con- 
cave recess 37 of the lower bearing 33. 
Tile lower bearing 33 is provided wuih ~i~lcri?al bores 
39 which exit froin nozzle openings 41 into hydrosiat~r, 
Iift pockets 43 within its top concave surface 9 aas wcll 
as its bottom planar surface 45. An oil lubricant is sup- 
plied uilder pressure to the internal bores 39 "cilrougk an 
adjustable, pressure-compensated Row conTroi valve 47. 
The oil enters the pockets 43 within the lop and bottom 
surfaces 37 and 45 of the lower bearing 33 and fills them 
so that the hydrostatic pressure will sepalate tile opposed 
snrfaces of the upper and l o ~ e r  bear-~ngs 31 and 33 as 
well as the opposed surfaces of the lower bearing 33 
and the top of the piston 21. The oil 611s out the gap 
formed by the separating surfaces and flows coi~iiw,musiy 
therethrough. The oil exits front the gap and spitis over 
the sides of the bearing 19 and piston 21. 
The use of a thick oil film for a hydrostatic bearing is 
well known. The pressure of the oil during its passage 
through the gap lifts the test object 11 a few thousandths 
of one inch. Pnitialiy, the lift is only due to the pres- 
surized pocket areas 43 but in free Boating condit~ons, 
the whole pressurized surface area contributes to thc Iift. 
For the gap to be stable, the outlets of the ducts or bores 
39 must be small enough to maintain a near constant Wow 
of oil independent of the gap pressrrre. For example, 
3,310,880 
3 4 
a decreasli~g gap vqill increase the flow resistance of the the stanchions 29 so as to contact the projecting rim $5 
gap but a constant flow will create higher gap pressures. of the u2per bearing 31 and prevent any unsual move- 
The overall rclult is that the gap resists changes in its ment. 
wrc'th and ilii~s 1s quite stable. The hydraulic line 91 to the valve 47 should be flexible 
The two rlros 25 and 27 used to guide the piston in its 6 so as not to interfere with the oscillatory motion of the 
vertical movements also are the hydrostatic type and func- test vehicle 11. The other hydraulic lines 94 and 95 to 
tion sii~ill~irly CIS thn self-adjus'iiilg bearing arracgement the valves 55 and 69 may be rigid. 
19. The incer surface of the rings 25 and 27 have a As only one type of oil shall be circulated through the 
plurahlq of syrnn~e~r~cally spaced hydrostatic pockets 49, hydrosthtic bearings 19, 25, and 27 and capillary seal 63 
sce FIGURE 5, and an internal duct system 51 wkich of the p:ston 211 and cyl~nder ring 57, a single oil pump 
emis inta 1 11czzie opening 53 within each p~cket .  The 93 may be used to force the oil into the hydraulic lines. 
pressur~zed oil is delivered into the duct system 51 through In the case of a power failure, the inlet valve 69 for 
an aaluslable pressure-compensated valve 55.  The noz- the oil flow inlo compression chamber 63 should close 
zle 53 is des~g~led to provide for a constant oil nov? lor automatically so only the capillary area 63 is available 
each pocket 49 so the system will have good stzbillty. 15 as a passage. This will enable the test vehicle 13 to sink 
Whlb only one flow control valve 55 has been illustrated, at a very slow rate down to the stanchions 29 and avoid 
it is apparent that the number of valves and the internal any appreciable rebound force. 
duct system may be easily modified so  each pocket or The overflow oil from the hydrostatic bearings 19, 25, 
some otl-ier select group of pockets may have a separate and 27 and capillary seal 63 of the piston 21 is collected 
011 feed system. 20 iiito an annular pan 95 projecting outwardly from the 
As shown best in FIGURE 3 the piston 21 ielescopcs bottom of the cylinder ring housing 23. A tube 97 drains 
into a cylinder ring 57 defined by a housing 23 which the oif through a filler 98 back to the pump 93 so the oil 
has an enlarged bottom portion 59 forming an oil corn- may be recircnlated. 
pression chamber 61. The contiguous surfaces of the If the test object 11 is a !multi-stage rocket as shown 
piston 21 and cylinder ring 57 serve to form a capillary 25 in FIGURE 1, two sets of hook-shape springs 99 should 
seal area 63. be propicled, one at the upper level and hinged to the 
A constant fiow of oil as indicated by arrows 65 enters spice joint between the two stages and the other at the 
the o ~ l  compression chamber 61 through an inlet 6'7 lower level near the support bearings 19. The flexing 
within the enlerged boitom portion 59 having an adjust- lever arms of the springs 99 will keep the vehicle 11 from 
able flow control vaive 69. The oil leaks through the 30 leaning against the snubbers 87 during the dynamic test- 
capillary area 63 bztween the piston 28 and the cylinder ing. By using soft springs and placing them advanta- 
ring 57, but because of the relative high flow resistance geously the reaction forces of the springs can be reduced 
of the capillary area 63 the oil flow builds up a pressure considerably. Thns, their location should be near nodal 
beneath the piston 211. If the overlapping length 63 be- points for dynamic bending tests. 
tween the piston and cylinder increases, the flow resistance 33 An electromagnetic shaker 310 such as illustrated in 
will also increase causing a greater build-up of pressure FIGURE 2 could be used to impart the desired motions 
beneath the piston 21. As this increase of pressure to the vehicle 11 during the dynamic test. The shaker 
hinders an mcrease in the overlapping length 63, the 110 shown is electrically operated to give a push-pull mo- 
piston 21 is forced into an equilibrium position similarly tion to a rod 112 which is attached to the upper bear- 
to a spring. 40 ing 38. 
The above reactions of the piston 21  occurs at a very The hydraulic support 13 of the present invention 
slow speed characterized by a relative high time constant give "six degree" freedom of frictionless motion to the 
of several minutes for position changes caused by an test vehicle 11. Any horizontal motion as well as rota- 
external force. tional motion about the vertical is obtained by the self- 
Howeter, since for any oscillatory motions, it is de- 45 adjusting bearings 19. The vertical motion is obtained 
sirable to have a relative soft or low spring constant, a by the use of the floating piston 21. 
pocket of air or gas 71 is provided within the oil com- Thus, it is apparent that a novel support for the dy- 
pression chamber 61  whereby the total volume of the namic testing of space vehicles has been disclosed which 
oil and gas within the oil compression chamber 61 may substantially achieves free flight conditions. With this 
change rapidly in response to oscillatory loads on the 50 hydraulic support, the test vehicle loads the ground only 
piston 21. and not a test tower or roof structure. 
This is accomplished by having an annular pocket 73 Obviously many modifications and variations of the 
within the upper portion of the chamber 61 in which a present invention are possible in light of the above teach- 
Aexabie container 75 is located. An inlet tube 77 with a ings. It is therefore to be understood that within the 
pressure regulating valve 79 enters through the walls of 55 scope of the appended claims the invention may be prac- 
the annular pocket 73 and of the flexible container 75 ticed other than as specifically described. 
so air under pressure may be pumped into the flexible What is claimed is: 
coniainer 75.  A hose 81 connects the valve 79 to a suit- 1. A hydraulic support, comprising: 
able pneumatic pump 83. (a)  a housing having an upper cylinder ring and a bot- 
The flexible container 75 will prevent absorption of 60 tom portion defining an oil compression chamber; 
the gas 71 5y the oil. By reducing the volume of the (b) a piston telescoped within said cylinder ring so  as 
gas 71 by one-half, the spring constant will be doubled. to form a capillary seal area between their two con- 
The upper bearing 33 is secured to the test vehicle 11 tiguous surfaces, said seal area having sufficient clear- 
and has a circr~lar projecting rim 85 forming its top sur- ance between the piston and the cylinder ring to face. Tke projecting rim 85 extends over the stanchions 65 oil to leak therethrough with a high flow 29 whose bottom end is secured to the housing 23 en- resistance; 
closing the oil compression chamber 61. The rim 85 of 
the upper bearing allows the test vehicle 11 to set directly (c) means for producing a continuous Bow of oil into 
on rhc ~ert ical  seanchions 29 without loading the self- said oil compression chamber so that the oil will 
adjusting be->ri.ngs 19 and the piston 21. This is necessary 70 pressure beneath the piston and leak 
during the test vehicle's installation or during a power the capillary seal area; 
failure. (d) air chamber means within said compression cham- 
Any lopgliilg of the test vehicle 11 or sliding off the ber which allows the total volume of the oil and air 
piston 29 is prevented by adjustable snubbers 87 which within the compression chamber to change rapidly 
are threaded thrrmgh the upper projecting flange 89 of 75 in response to oscillatory loads on the piston. 
3,310,980 
5 6 
2. A hydraulic support as defined in claim 1, including: ( f)  said enlarged bottom portion having an inlet corn- 
(a)  hydrostatic ring bearing means for guiding the municating with said flexible container far admitting 
piston projecting from said cylinder ring. gas within said flexible oontainer. 
3. A hydraulic support for use in the dynamic listing 
of space vehicles, comprising: 5 References Cited by the Examiner 
(a)  a housing having a cylinder ring and a bottom 
portion forming an oil compression chamber; UNITED STATES PATENTS (b) a piston telescoped within said cylinder ring; 3,015,315 1/1962 Strimel ----------- 92-162 X 
(c) said piston and cylinder ring forming a capillary 3,226,103 1211965 McNenny --------- 188-96 X 
leak area between their two contiguous surfaces; 10 FOREIGN PATENTS 
(d) means for producing a continuous flow of oil into 
said oil compression chamber so that the oil will build 1,228,272 3/1960 France. 
up pressure beneath the piston and leak through the 
ca~illarv leak area: RICHARD C. QUIESSER, Prinzavy Examiizcr. 
(e) flexible container within said oil compression 15 J. W. MYRACLE, Assistant Examirter. 
chamber; and 


Hydraulic support for dynamic testing Patent

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