Yes, they have to be fun, comfortable, light, powerful, look cool and be
convenient. The most talented
designers will accomplish all that and
provide decent protection. No, they won't be foolproof and
yes, training is just as important. But, as the airlines have discovered, the
best safety improvements come through both passive-safety hardware and
hand at left is an example of why one feature, frangible props, are
so beneficial: this hand went into a prop and survived. The
lightweight wood exploded, minimizing damage to the hand which eventually healed. Of course having other features, namely a
cage that keeps the hand out of the prop, would be far better.
Prop Safety and A
Better Throttle which includes
animations with some of the safety
ideas mentioned here.
See also A
here are some recommendations that could improve safety in order of
importance except that item 5 would probably be better placed at #1.
Paramotor cages should prevent an open human hand from going into the prop at full rated thrust.
The netting openings must be small enough and far enough from the prop,
especially outward where the tips are closest to the net. A two-hoop design,
with an inner and outer (see
illustration), helps where one hoop
is mounted forward of the radial arms
with a radius nearly the same as the prop. That is the most critical
radius since it is closest to the prop. Plus, this type of inner hoop would be an easy retrofit.
Props should be frangible—strong enough to push air nicely but
weak enough to break before bones break. I’ve seen some pretty thick
clubs that would be unforgiving at best.
The pull start and hand hold should be arranged so as to put the
human in a position to easily handle a thrusting motor should it go to
The netting and cage should protect the pilot during landing flare
or if the pilot falls and instinctively puts his hands back towards
the prop—a natural reaction.
Protection must be included down low on the cage. It should also keep hands out of the prop for pilots reaching
Motors should have
some form of
SafeStart™ (See below, this panel), or
similar, a system that prevents the motor from exceeding idle RPM while starting. It should be accessible from the pilot’s seat and double as an emergency shutoff in case of a failed kill switch.
This yet-to-be developed system has at least Off and Run positions where the motor
will shut off if the RPM exceeds a set value within the first 5 seconds of
would prevent a full-throttle situation from driving the motor forward
Another version, with "Off, Start, Run"
would be similar.
You’d start it in the start position then, once running, put it in the
run position where full throttle is available. This would also serve as an
alternate kill switch (“off” position) should the primary fail. The
motor won't start in the run position.
Feb 3, 2013 The gas tank should be far enough away from the propeller tip to
keep the propeller from slicing into it during a hard landing or crash.
That has occurred at least 6 times that I know of, leaving the pilot
engulfed in an explosive vapor—one spark away from igniting.
4" for short props (less than 40" long) and 6" of clearance
on longer props.
Even better is a design, as shown on the illustration, where the
tank curves away from the prop near the bottom.
The harness buckles should be of a quick-release type. Old style
rectangular fittings that require angling one part out of the other are
unacceptable since they would make escape difficult after a water
A single buckle that undoes both legs at once is unacceptable
because it allows the occupant to make one lethal mistake. A quick
release for all but one leg loop would be beneficial to allow for quick
escape in the event of immersion.
harness should not be able to slide, or allow any fittings to slide
such that the flight characteristics are significantly altered. Most
notably, the clip-in points must not be allowed to slide or be easily
connected improperly. Adjustable
settings should prevent errors as much as possible. Examples are the free-flight
harnesses that prevent pilots from forgetting their leg straps—that is a
design that has saved lives!
Harness and general design must also minimize torque effects.
Torque-related issues represent probably 20% of inflight accidents although
many are minor because the crash happens just as the pilot takes off.
Torque effects can be minimized.
The harness and frame should offer
some protection in the event of a
near-vertical type crash such as would result from a parachutal stall. In
flight, the motor hangs from the harness, but in a crash, the pilot will
be forced down against the seat and frame. The frame should absorb impact
and the harness should be mounted stoutly enough to stay attached. The
common criteria for airplanes is a 9 G deceleration, meaning that if the
frame hits the ground with a deceleration force of 9 G’s, it would
remain intact enough to protect its occupant. It may deform along the way.
Another method may be to use several inches of
crushable foam (such as what goes in helmets) on the seat bottom and
an inch on back, in addition to any padding that's normally there.
Implementation must allow the seat bottom to fold completely up against
the frame to allow easy running (foot launch only).
The motor should be stable when sitting. Tippy motors tend to fall
over making it more likely for gas to spill onto the harness. Plus,
frame bottom should prevent a pilot's leg from getting into the prop. That
sounds unlikely but it has happened. Last, the bottom frame should be sufficiently rounded so
as to slide upward if it hits something sharp on the ground.
The prop should
not stick out the back. It would be enclosed enough to prevent a hand from reaching it
even with the pilot stretching wildly.
The diagramed unit does this, see #10 and hand
#1s. An extra hoop behind the main cage rim could add sufficient
protection while being an easy retrofit (see diagram).
Several accidents have happened where pilots got their hands in the prop
during launch, in flight, falling or landing while the motor was
jostling. Some when their hand went around the cage even though they
found it impossible to do so while trying just standing or sitting.
The gas tank should be protected on the prop side with a material (maybe
a sandwich of external aluminum with foam on the gas tank side) capable
of taking a prop strike without breaching the tank. Not required on
machines where it's impossible for the prop to hit the gas tank.
should be some way to verify the carburetor is at idle when
A clutch reduces some risk during idling
and by allowing the prop to slow when the throttle is reduced without
having to hit the kill switch. Another benefit is that
it can reduce the number of times wing lines get
But it is every bit as dangerous in cases where the motor unexpectedly
goes to power.
Reduce the likelihood of the brake toggles going into the prop. Low hang
point machines are particularly vulnerable since the top of the cage tends
to move toward the risers on launch, putting the prop disk closer to
the brake toggles. I've seen this happen myself and heard about quite a
few more. It may simply require a bigger cage, another hoop (see above),
different hang point, or better netting.
This improved design (with help from Dennis Webster) makes the design even
more reliable while decreasing hassle.
Unfortunately, nobody is building the device,
as of November Feb 2013. It's apparently too much effort to too small a
market. I know the feeling! One company is working on it, we'll post it
here if they bring it to market.
Here is the page with a video showing how a
simple installation might work.
Here are some of the ideas that would make a safer paramotor. It could, of
course, look radically different. One major part of this is to show how
the 2nd hoop could be retrofitted to existing designs. Another hoop, to
better enclose the prop could be added to the cage rim. Updated July 18,
This "Outlaw," prototype, shown here without its netting,
completely encloses the prop. It would likely be difficult
to get a hand into the prop while reaching back. Of course another benefit
is better protection of the lines.
This example of the inner safety ring, put on at the prop's radius, was
done by Jeff Baumgartner in about an hour. Although the bar is taped on
here, a pair of hose clamps at each intersection could also be used for a
secure fitting. Ideally the second ring would go all the way down.
Pilots have gotten their hands in the prop during large flares while
1. Kevlar net lines are strong and resist stretching.
2. Fuel tank placement well forward of the prop prevents
a prop strike during vertical impacts.
3. Fuel tank placement on top of the motor also prevents the chance
for a prop strike in a vertical crash. Experience suggests there is no
appreciable risk from
fuel leaking onto the motor.
& Flying Feel
is probably the single biggest reason why most people stick with a
machine--it's comfortable and fun. The ideal machine would incorporate the
above safety features, look cool and have the comfort/feel attributes
mentioned here. If you want to find out what people like, talk to those
who are on their 2nd or 3rd machine. The first machine is frequently the
one sold by the instructor (which is a good reason to buy it because the
instructor knows how to teach it) and a pilot who's only flown that
machine won't have anything else to go on. The same is true for wings, of
course, but this only deals with motors.
lot of what pilots perceive as comfort and feel depend on their style.
The seat and back support should be comfortable.
The motor should be well balanced on the ground and in flight with minimum
moving around except for that desired by the pilot (such as weight shift).
For pilots who like to use weight-shift steering, it should be effective
and require the least amount of effort. This will trade a "busy"
feel as the wing imparts feel back to the pilot in the same way the pilot
imparts steering inputs to the wing.
The risers should be far enough from your arms to avoid impinging motion.
There should be adjustments to accommodate individuals or desires.
Torque effects should be minimized. Yes, this is a safety feature too but
it's just no fun to manage a unit that twists too much every time you add
You should be able to easily launch it. A machine that won't get you
airborne is worthless. The wing is obviously important, too, but a poorly
designed paramotor can be unlaunchable. I've been there before.
Vibration should be minimized. Some makers have achieved good results by
having two sets of motor mounts but this may motor farther from your back
Balance is important. A motor that is always pulling you back will quickly
tire your stomach muscles.
The first 2 images show that a machine hanging low on your back will not
allow you to move the CG forward by leaning. Even if you lean forward it
will still be pulling you back.
Not shown but apparent is that the machine's CG should be close to your
body. That enables leaning forward to effectively balance you. It is more
difficult for low hook-in machines because the thrust line is best placed
near the hook-in point.
This frame curves like a mountain backpack and is very comfortable,
especially on long flights. 2 inches of back padding also helps.