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2.  Started for hobby rocketry recovery in 2007.
Rocketry recovery is very demanding in terms of
harsh recovery situations – high speeds, altitudes,
stuff goes wrong a lot! Strength is very important.
 Began to sell to emerging sUAS users around 2009.
 sUAS is now outpacing other industry segments in
need for Parachute Recovery Systems (PRS).
 Sold well over 1000 UAS systems to large range of
customers. Many companies are integrating now.
Earned a place as a topic expert!

4.  Some Fixed Wing systems need PRS – they are
primary or backup recovery.
› Examples, no landing gear, PRS is primary recovery
› Limited space to land, i.e. in the mountains or rugged
terrain.
 Other drivers toward the need for Parachute
Recovery Systems (PRS)
› Safety – Protect people and property
› Regulatory – Not lost on government agencies is backup
safety systems make sense for public safety.
› Insurance – Insurance companies drive need via lower
premium rates or even mandate to get insurance.
› Cost of Failure Mitigation – Parachute safety is a fraction of
UAS cost in case there is a failure.

5.  UAS Systems not fool proof, they fail.
And any system, even with redundancy,
can also fail.
 Can be mechanical, electrical, software,
environmental – think wind, rain, etc.
 Failure result usually similar, impact into
the ground!
 People can be hurt, and property can
be damaged.

6.  Government agencies primary driver is need to protect
the public.
 They recognize even the best systems can fail.
 Safety systems like parachutes greatly lessen risk of injury
or property damage. But PRS are not perfect either.
Still, UAS with PRS have statistically much better
outcome than not!
 Many EU countries now mandate. Australia, and some
South America countries do as well.
 ASTM F38.02 subcommittee WK37164 is working on
safety standards for commercial use over populated
areas. Parachute safety is part of the standard.

7.  Insurance industry driven by risk
assessment vs cost of claims settlement.
 PRS in their eyes is a quick win –
statistically lowers risk of personal injury,
and reduces property damage.
 Some companies are requiring PRS in
order to get business operational liability
coverage. Also will lower premium fees.

8.  Why most people contact us about a
PRS. A $50K system can be protected for
<5% of the UAS cost!
 Alternative is failure that can lead to
total UAS loss.
 PRS makes sense when the value of the
UAS is 10x or more cost of the PRS.

9.  There are many styles of parachutes.
We’ll discuss the various types, the
advantages and disadvantages of most
popular chutes… These include:
› Flat Sheet Parachute
› Multi-Panel Parachute
› Elliptical, or Conical Parachute
› Annular, Pull down Apex, Toroidal
 And why it matters!

10.  Before we start there are challenges in comparing
designs:
› Inconsistency in how chute size is sold to the user.
 Some as canopy area
 Some as circumference around top of canopy
 FC measured based on projected frontal area, i.e the opening
diameter
 Complex canopy shapes make comparison hard.
› Ultimately you want to know a chute’s design coefficient of
drag, or Cd, for a given reference area.
› Knowing the Cd is essential to calculate the descent rate under
any given weight, size, and base altitude.
› We feel it’s simplest to measure the chute based on the opening
diameter of the skirt. The “reference area” is simply the area of
the opening. This along with the Cd and you can predict chute
performance at a given size, and load weight!
 Goal in design is to maximize drag at least possible weight.
This means a higher Cd is essential!

11.  Advantages:
› Simple Design
› Low Cost
 Disadvantages:
› Low Cd of approximately 0.7 to 0.8
› Bulky for a given load
› Poor Stability, can oscillate above the load
› Lower strength – this is partly due to materials selection

12.  Advantages:
› Good stability, stays above the load
› Very strong, usually has over-the-top riser connections
› Fewer risers to tangle – easier to untangle if they do
› Probably most popular HP Rocketry style currently
 Disadvantages:
› Moderate, Cd of approximately 1, little published info on this. Type not used
outside Rocketry and racing that we can find.
› Use heavier webbing for shroud lines (fewer connections to carry the load)
› More complex design, two to three pattern shapes needed. Uses a lot of tape
reinforcement on edges and on all seams leading to higher weight.
› Can rotate under load due to variations in symmetry.
› Can sometimes breathe under slower descent (jelly fish)
› Limited use in UAS as far as we can tell

13.  Advantages:
› Good stability at lower speeds, stays above the load
› Good strength-to-weight ratio
› Better efficiency, Cd of about 1.5 – 1.6
› Packs into smaller space per load rating
› Simple repetitive design – only one pattern shape needed
 Disadvantages:
› At high speed it can wobble
› Multiple gores means more sewing and higher cost

14.  Advantages:
› Good stability at typical main chute descent speeds.
› Good strength to weigh ratio
› Very high efficiency, Cd of about 2.2 – 2.4. Noted as the highest known Cd for
unguided chute for a given canopy area
› Packs into smallest space per given load rating
› Simple repetitive design – only one pattern shape needed
› Fast opening good for low altitude UAS
› Popular as reserve chutes for parachute jumpers, hang gliders, and ultra-lights
 Disadvantages:
› Not as good at high(er) speed
› Very fast opening can also cause high opening shock load
› More complex to make, apex pull down adds to complexity and cost

15.  Ideal parachute has the highest load
capability at least weight. This means a
chute with a high Cd is better.
 Different parachute designs can be boiled
down to a single number called
“Performance Rating” (PR) and then
compared objectively.
 PR is simple ratio between the parachutes
load capability at a given descent speed
divided by the parachute’s static weight.
 Higher is better!

16. Chute Type Chute size
determined by:
Cd Reference
Area
Stability Cd Performance
Rating @ 15
fps **
Use
Flat Sheet Distance across
fabric
Area of fabric Ok at low speed,
poor at high
speed
Low – 0.7 Approx. 8:1 Main or drogue
Panel Style Distance across
top panels,
usually on
diagonal
Area of fabric Good vertical
stability, can
rotate or spin
Med – 1.1 Approx. 10:1 Mostly as a Main
in Rocketry
Elliptical ,
spherical,
conical
Opening
diameter, or
canopy
circumference
Area of
opening
Medium high
speed, Good low
speed
Med – 1.6 13.4:1 Main or Drogue
chute
Annular
(Iris Ultra)
Opening
diameter
Area of
opening
Good medium to
lower speed
Highest at
2.2
30:1 High
performance
main chute.
Ideal for UAS
recovery

17.  We will discuss several methods of chute
deployment:
› Fixed Wing UAS deployment using a
Deployment Bag and pilot chute
› Compression spring based Parachute
Launchers
› CO2 Ejection Systems

18. › Passive, requires forward flight and air
movement for extraction
› Used for Fixed Wing UAS
› Small pilot chute used for extraction
› Simple and low cost
› Not suitable for Multicopters!

19.  Examples are Skycat Launcher, and MARS systems
 Active deployment does not require forward flight – use with
multicopters
 Relatively low cost
 Limited in chute size by spring strength to around 60”D chutes.
 Because of this max load around 10Kg system as a safety-only
device. Descent rate too high to eliminate damage.
 Can use with larger chutes by spring ejecting smaller chute
which acts a pilot for larger chute. But this delays deployment.

20.  Examples Peregrine Sentinel, Peregrine IDS, DJI
Dropsafe
 Active ejection using CO2 gas, more energetic
deployment, shorter deployment time.
 Peregrine systems rated up to 100Kg loads.
Features high packing density, resulting in small
size.

21.  Manufacturers are not necessarily thinking of facilities
to add parachute recovery to products.
 Parachute deployment channel needs to be
standard on all autopilots (some have this.) Both
manual, and programmatic based.
 Backup failsafe devices separate from autopilot
need to be developed to do automatic algorithmic
deployment when risky situations are encountered,
like fast descent speed, unsafe attitude (sideways or
upside down,) out of bounds, etc…
 ESC need failsafe override to cut power in case
failsafe activates. You can not deploy a parachute
system if rotors are active!
 Airframes designed to accommodate PRS. Currently
these are an afterthought and it’s up to the buyer to
figure it out.

22.  Download this presentation here:
http://fruitychutes.com/other_fun_stuff/genes_blog
/usb-expo-drone-parachute-tutorial.htm
 Parachute Recovery Tutorial:
http://fruitychutes.com/uav_rpv_drone_recovery_p
arachutes/uas-parachute-recovery-tutorial.htm
 Gene’s Blog, articles on recovery and other stuff:
http://fruitychutes.com/other_fun_stuff/genes_blog
.htm
THANK YOU!