Parachute with selectively adjustable brake flaps for controlling angle of descent

A parachute comprises a canopy having front and rear sections and a base with shroud lines attached to the base at circumferentially spaced-apart locations therearound. A plurality of brake flaps are disposed below the canopy base and between the shroud lines at the canopy rear section and are selectively adjustable between an inactive position wherein the brake flaps are fully slackened and interfere minimally with the inherent flight characteristic of the parachute and an active position wherein the brake flaps are fully extended and effectively brake the forward velocity of the parachute to thereby increase the parachute angle of descent. A set of control lines attached to the brake flaps selectively and adjustably effect actuation thereof between the active and inactive positions to accordingly control the parachute angle of descent.

The invention relates to a parachute with flaps which consist of parachute 
material such as parachute silk, synthetic fabric or the like and which 
are disposed on the canopy of the parachute. 
Controllable parachutes are known, the canopy of which is provided with 
control slots. Depending on their construction and arrangement, they can 
serve to steer the parachute to the right and left and also to influence 
the angle of descent of the parachute, especially in the case of a gliding 
parachute. 
Insofar as the control systems heretofore known function to bring about 
and/or influence the angle of descent of gliding parachute, such has been 
achieved with parachute canopies with a relatively complicated 
construction, which thus involves a correspondingly expensive 
manufacturing process. In addition, the control systems can often only be 
used for a specific type of parachute. The operational reliability of the 
gliding parachutes which are thus controlled is not always assured because 
of their complex construction which is complicated by control members. 
The problem therefore arises of improving the controllability of parachutes 
by means of flaps, in particular to influence the angle of descent, so 
that the flaps can be used substantially universally and parachutes which 
can thus be controlled can be produced at reasonable cost. In addition, a 
high degree of operational reliability is required for the parachute and 
the control system itself. 
According to the present invention a parachute comprises a canopy, shroud 
lines attached to the base of the canopy, and brake flaps fitted below the 
base of the canopy between the shroud lines on the rear section of the 
parachute. 
Gliding parachutes are already known wherein additional panels or webs are 
secured between the shroud lines, at the base and at both sides of the 
canopy, that is to say disposed opposite one another. However, they do not 
form brake flaps but simply stablilizing members which, in their 
arrangement in pairs opposite one another, are intended to stabilize the 
gliding flight path of the parachute. The arrangement and effect are 
similar to that of a ship's keel or a vertical control surface of an 
aircraft. Consequently they neither fulfil the purpose of influencing the 
angle of descent of the parachute, nor are they suitable for this purpose. 
The brake flaps provided immediately below the base on the rear section of 
the canopy, according to the invention, cause a drag force in a gliding 
parachute (in relation to the gliding direction as a forward direction), 
the magnitude of which depends on the number, construction and size of the 
brake flaps. 
The invention can also be applied to round-canopy parachutes. Round-canopy 
parachutes of normal construction glide or swing in an angular range of at 
least .+-. 20.degree. in relation to the vertical, or they execute a 
combined movement. The reason for this lies in the static instability of 
this parachute in the region of the zero-degree position. The unwanted 
swinging motions are avoided by using the brake flaps according to the 
invention. At the same time, a gliding motion is imparted to the 
parachute, actually in the range of about 8.degree. to 10.degree., but 
this is acceptable for many applications. Where it is desired to avoid an 
angle of descent, however, a small gliding characteristic can be imparted 
to the round canopy, which is then again compensated for by using the drag 
component. By this means, a swing-free flight is achieved with an angle of 
descent to the vertical of substantially 0.degree.. 
In any case, the brake flaps are preferably disposed in a row side by side 
in the rear section of the canopy so that they extend downwards from the 
base like an apron. 
For many purposes, however, a division is preferable so that the brake 
flaps are disposed in groups side by side, symmetrically in relation to 
the central axis of the canopy. As a result of the symmetrical arrangement 
of groups at both sides of the central axis of the canopy four, six, or 
even eight, etc., groups of brake flaps can be combined side by side. This 
solution acquires particular significance for canopies equipped with 
control slots, as will be explained later in detail. 
Particularly for load parachutes, it is possible to dispose the brake flaps 
in non-adjustable stationary positions. In the majority of cases, however, 
it is preferable, and in this there lies a very important feature of the 
invention, that the brake flaps should be arranged to be adjustable 
selectively between an active and an inactive position during the flight 
by the jumper or mechanically, for example by means of a harness. 
Intermediate positions are also possible. By this means the angle of 
descent of a parachute, particularly of a gliding parachute, can be varied 
in a relatively simple manner. If the angle of descent which can be 
achieved as a result of the construction of the canopy is to be fully 
utilized the brake flaps are brought into their inactive position. If a 
reduction in the angle of descent from the vertical is required, then the 
brake flaps are set in their active position or in some intermediate 
position. For this purpose, the brake flaps are so constructed and 
arranged that they reduce the propulsive force of the canopy so that even 
a vertical descent can be achieved. In any case, in their inactive 
position, the brake flaps assume a position in which the canopy 
substantially displays a flight characteristic which corresponds to that 
of corresponding canopies without brake flaps i.e., the brake flaps are 
fully slackened and trail behind the canopy and therefore interfere 
minimally with the inherent or normal flight characteristics of the 
parachute. 
The arrangement of the brake flaps in groups, distributed symmetrically in 
relation to the center axis of the canopy and their adjustability out of 
the active into the inactive position and vice versa is of particular 
importance for parachutes with known control slots arranged symmetrically 
at two opposite sections of the canopy. The controllability of the 
parachute, depending primarily on the effect of the control slots, can be 
substantially improved as a result of the fact that the brake flaps 
situated at one side of the center axis of the canopy, and which are 
disposed continuously in a row or in groups, can be actuated jointly with 
the control slot at this side in such a manner that they assume their 
active position when the control slot in question is closed. Of course 
this also applies when there are a plurality of control slots at each 
side. 
It is known that for a left-hand curve of the parachute, the control slot 
situated at the left-hand side of the canopy is actuated, that is to say 
closed, so that the canopy is given a counterclockwise movement as a 
result of the action of the control slot situated at the right-hand side. 
If, in addition, the brake flaps which are likewise situated at the left 
of the center axis of the canopy are wholly or partially set in their 
active position, it is possible for the parachute to fly a very tight 
left-hand curve. The effect of the control slot is effectively reinforced 
by the brake flaps situated on the left. The actuating members for the 
associated control slots and brake flaps or groups of brake flaps are 
therefore connected to one another for simpler operation. If, instead of a 
left-hand or right-hand control, the angle of descent of the parachute 
merely has to be altered, then the systems of control slots and brake 
flaps situated at the right and left are actuated jointly. In this case, 
too, their effects are added and combined together. 
The effect of this combination is comparable to the combined effect of side 
rudder and aileron in an aircraft. As a result of actuation of the rudder, 
a rotation about its vertical axis is imparted to the aircraft, comparable 
to the actuation of a control slot. If the corresponding aileron is 
actuated in addition, a considerably tighter curve of the aircraft is 
rendered possible, comparable to the effect of the additional actuation of 
the corresponding group of brake flaps. 
The brake flaps are preferably adjustable as a result of the fact that the 
upper edge of each brake flap is secured to the base, and control lines, 
which extend to the jumper or to a mechanical harness and which are taken 
to adjacent shroud lines, are provided at the lower edge and particularly 
at the corners of the brake flaps. The control lines can be connected to 
the shroud lines by means of rings for example. If a pull is exerted on 
the control lines by the jumper or mechanically, then the brake flaps 
unfold from the base until they have reached their full size below the 
canopy and are held in this position by the control lines. If the pull of 
the control lines is relaxed, then the brake flaps are pulled upwards 
towards the edge of the canopy either automatically by the force of the 
air or mechanically. They are allowed to float in the wake of the flow of 
air flowing round the canopy where they cannot exert any appreciable 
effect on the flight path of the parachute. 
There are a number of different possibilities for the shape and 
construction of the brake flaps. Fundamentally, preference should be given 
to brake flaps which are made permeable either by the provision of 
apertures or by the use of air-permeable material or by a combination of 
air-permeable material and apertures. The permeability of the brake flap 
realized in one form or the other counteracts an unwanted bearing of the 
air stream against the brake flaps, so as to prevent too powerful a drag 
force which might cause the parachute to fly backwards. Only when it is 
desired to use the brake to reverse the direction of movement or gliding 
of the parachute from forward to backward flight, would brake flaps with 
relatively little permeability or even impermeable brake flaps be used. 
The brake flaps are preferably constructed in hood form, in conjunction 
with the above-mentioned permeability conditions, and an aperture at the 
end of the hood (seen in the direction of the air flow through the hood) 
has proved particularly effective. 
It has been found that a hood shape is particularly preferred wherein the 
brake flap has a cover which, in the active position, forms a 
substantially rectangular opening for the inflowing air with an extension 
following upwards in the form of a substantially semicircular widened port 
bounded by the adjacent edge of the base and with a substantially 
triangular rear wall opposite the opening and the widened portion at the 
other side of the control flap. The base of the rear wall coincides with 
the lower narrow side of the opening and extends upwards from there at an 
angle of 30.degree.-80.degree., and preferably 60.degree., to the area of 
the rectangular opening, where a rounded triangular point is cut away as a 
port. 
As a result of this shape, a very powerful braking effect and an effect on 
the angle of descent which is stabilizing to a high degree is imparted to 
the brake flaps. In addition, any swinging is avoided in a gliding 
parachute thus equipped. In the inactive position of the brake flaps, an 
optimum gliding flight is achieved and in the active position of the brake 
flaps, a vertical flight can be set. An unwanted backward flight is 
avoided as a result of the cooperation of the shape of the brake flap and 
the flow of air through the port and through the walls of the brake flap. 
Instead of the above-mentioned hood shape, it is also possible that the 
brake flaps may be constructed in the form of networks of bands, strips or 
rings of parachute material. As a result, ports for the flow of air are 
formed distributed over the whole area of the brake flap, as a result of 
which the application of the air flow with the unwanted consequence of a 
very powerful drag component is avoided. Instead, here too, as when the 
hood shape is used, a flow pattern develops which is symmetrical to the 
center axis, and, in their active position, the brake flaps render 
possible a variation of the flight path of the parachute out of the flat 
gliding flight into a steeper or into a vertical flight. Thus they permit 
a control of the angle of descent within wide limits. 
In special cases, it is also possible for the brake flaps each to be 
constructed in the form of a plane closed section of parachute material or 
a similar flexible material. Since, in this case, however, application of 
the air flow generally occurs, a backward flight of the parachute thus 
equipped can scarcely be avoided when the brake flaps are fully extended, 
so that this form of embodiment is recommended particularly when a 
reversal of the direction of gliding is required.

The canopy 1 of a gliding parachute, illustrated in FIGS. 1 and 2, has an 
aerofoil wing-like profile in the side view of FIG. 2 with shroud lines 2 
being attached at the edge or at the base 4 of the canopy 1 in the usual 
manner. The gliding characteristics of this type of parachute depend not 
only on the aerofoil wing characteristic and other features but also on a 
flow deflector 7 disposed centrally above the canopy 1 and transverse 
slots 3 in the rear section of the canopy. 
At the rear section of the canopy, five hood-shaped brake flaps 5 are 
disposed immediatley below the base 4, in a symmetrical arrangement, as 
can be seen from the drawing, and each is positioned between a pair of 
shroud lines 2. 
FIG. 3 shows that two control lines 6, which are provided spaced apart at 
the lower corners of the brake flap, are provided at the lower edge 12 of 
such a brake flap 5 and extend toward and run along the lengths of the 
adjacent shroud lines 2 by means of rings 18. 
When a downward-acting pull is exerted on the control lines 6 by the jumper 
or in a mechanical manner, for example by means of a harness, the brake 
flaps 5 assume the active position illustrated in FIGS. 1 and 2 and 
particularly in FIG. 3. If the pull relaxes, then the brake flaps 5 are 
pushed upwards or folded up towards the edge or towards the base 4, either 
automatically by the force of air or mechanically, the control lines 6 
sliding upwards, following the brake flap 5, through the rings 18. The 
brake flaps 5 then float somewhat in the wake of the air flow in the 
manner which can be seen from FIG. 4. In this position, the brake flaps 5 
assume a so-called inactive position. In addition, intermediate positions 
are possible. 
FIG. 3 shows that the hood-shaped brake flaps 5, which are made of 
parachute material, have a cover 8 which, when curved forms, internally, a 
substantially rectangular opening 11, which is partially indicated by 
broken lines and which is bounded by a lower and an upper narrow side 12 
and 15 respectively and longitudinal sides 13, 14. At the top, a 
substantially semicircular widened portion 16 follows on the opening 11. 
At the back of the brake flap 5 there is substantially triangular rear 
wall 9, the base of which coincides with the lower narrow side 12 of the 
opening 11, while a port 10 is left free at the rounded upper triangular 
point. Depending on the form of embodiment, the rear wall 9 extends at an 
angle of about 60.degree. to the longitudinal sides 13, 14 of the front 
opening 11. Further details follow in connection with FIGS. 15 - 17. The 
brake flap 5 assumes the shape described in the active position, and the 
air entering the opening 11 and the widened portion 16 can emerge again 
through the port 10. 
In the illustration shown in FIG. 4, the brake flaps 5 are in the inactive 
position so that the flight path of the parachute is determined by the 
angle of descent (measured in relation to the horizontal), as illustrated 
by the arrow 20, which would also be the determining factor if no brake 
flaps 5 were disposed in the rear section of the canopy. In contrast to 
this, in the illustration shown in FIG. 5, the brake flaps 5 are in their 
fully unfolded position, that is to say in the active position, in which 
they alter the angle of descent. In the present form of embodiment, the 
shape, size and number of the brake flaps 5 is such that, in the active 
position, the brake flaps 5 bring the angle of descent to 90.degree. and 
so render a vertical flight of the parachute possible. As already stated, 
intermediate positions are possible for the brake flaps 5, in which only a 
greater or lesser alteration of the angle of descent is caused, without 
vertical flight occurring. 
In the second example of an embodiment as shown in FIGS. 6 - 9, planar 
brake flaps 5' in the form of nets are used, which consist of bands, 
strips or rings of parachute material or a similar flexible material, that 
is to say substantially of the same material as the hood like brake flaps 
5 described previously. As a result, each brake flap 5' is permeable 
across its area in relation to the air flowing towards the brake flaps 5'. 
This permeability prevents the air flow causing an undesirably strong drag 
force which can lead to the backward flight of the parachute. 
Apart from this, the planar and net-like brake flaps 5' are fitted and 
controllable in the same manner as the brake flaps 5 so that a more 
detailed description of the drawings can be dispensed with. FIG. 9 
illustrates the bringing about of a vertical flight of the gliding 
parachute and such is achieved by actuating the net-like brake flaps 5' to 
the active position. 
The further example, illustrated in FIGS. 10 - 12, corresponds in 
construction and arrangement of the brake flaps to the example described 
above, but instead of the brake flaps 5' of net-like construction, brake 
flaps 5" of planar and closed construction formed of parachute material 
with the usual air permeability are provided. With these brake flaps 5", 
which are fitted and controllable in the same manner as in the previous 
examples, there is an application of the air flow in the active position 
and a resulting powerful drag force. Therefore, this form of embodiment is 
preferred above all where a reversal of the direction of gliding from 
forward flight to backward flight is desired. 
FIG. 13 shows that the brake-flap system according to the invention can 
also be used on round-canopy parachutes. The normal gliding characteristic 
of the round canopy 25 is partially compensated in the above position of 
the planar, net-like brake flaps 5' used therein. As a result of the use 
of the brake-flap system, above all, the uncontrollable and unwanted 
swinging of the round-canopy parachute is avoided, while a slight angle of 
descent which remains despite the brake flaps 5' and which is illustrated 
by the arrow 26, can easily be accepted. 
The same applies to the round-canopy parachute as shown in FIG. 14 where, 
instead of net-like brake flaps 5', hood-shaped brake flaps 5 are used, as 
already described in detail with regard to construction, shape and effect, 
in connection with FIGS. 1 - 5. 
FIGS. 15 - 17 show in detail the shape and relative dimensions of the 
hood-like brake flap 5 illustrated in FIG. 3, all dimensions being 
expressed as fractions of a unit length of that arc which bounds the 
semicircular widened portion 16 of the opening 11. FIG. 15 shows the shape 
of a hood-like brake flap 5 already described, while the development of 
the sheath 8 is represented in FIG. 16 and a plan view of the rear wall 9 
in FIG. 17. It is understood, of course, that the scale illustration and 
description are not intended to represent any restriction of the 
invention, but merely a concrete example of a type which has proved 
satisfactory in test trials.