How Much Power Do I Need?
You'll notice the name of this article is not "How much power
do I want?". Do what you like. However, there are other considerations
besides power that need to be addressed like, quality, weight, service
support and how quite the motor is. I would like to give some guidance
to the new pilot who's trying to figure out want they really need.
Currently there is a contest to see who can make the biggest, most
powerful motor. This is an overreaction to the bad old days of paramotoring
where most the rigs were underpowered. These days most motors have
all the power you need and some have a lot more.
You do need a minimum of power to safely fly. First let's look
at how power is measured. Pounds of thrust is what is important
to you. How big the engine is, how much horse power it has, means
nothing if you can't turn that power into thrust. Here's an example,
I fly a paramotor with a 210cc engine which puts out 110 pounds
of thrust. There is another motor on the market that is 202cc that
puts out over 160 pounds of thrust. A well engineered motor needs
to balance the design of the prop, it's length, surface area and
pitch to the power band of the engine.
You need an honest measurement of the motor's thrust. There is
a device you can put a motor in, to measure this. The motor should
be tested with the harness in place with a pilot sitting in it.
There needs to be neither a head or tail wind to bias the results.
I currently fly with a 110 pound of thrust at 5000 to 6000 foot
launches with wheels. I only get about 150 foot per minute climb
rate. this not enough. I bought this motor when I was still foot
launching, without the weight and the drag of the wheels it got
around 225 fpm climb rates.
I recommend that your motor should have enough power so that, with
your glider, at your weight and at your density altitude, (I'll
get to density altitude in a moment.) you have a minimum climb rate
of at least 200 feet per minute. I know I going to catch grief from
the power mongers over over this figure, however 200 fpm will get
you off the ground and you can fly around and go sight seeing. Big
Fun! Let's knock off a few of the aurgements for big power,
1. That's not enough power to escape big sink. Well, nothing has
enough power to escape big sink. I have been a free flight thermal
pilot for for years, I've encountered sink as high as 2000 fpm.
Nothing, comes even close to having that kind of climb rate. There
is only one way you are going to stay safe in this sport and that
is by exercising good judgment. If you are going to fly in active
air you need to know how to do so. You need to know your weather,
your surge control, how maintain the internal pressure of your glider
and have more sense than a jellyfish. You have only one piece of
safety equipment and that under your helmet and between your ears.
No amount of power can save you from flying air you don't belong
in. (You'll notice some pilots don't fly with helmets. That because
they haven't brought the above mentioned piece of safety equipment
2. I'll have too run a long way to take off. With a 200fpm climb
rate you'll take off after running around 10 to 15 steps in light
winds. The glider will take off when it reaches take off speed.
If you are foot launching, it's your ability to run that gets you
to take off speed. Although the prop pushing you does help somewhat,
it can't push you more than you can run. Most long runs come from
poor launch technique. If you taught yourself to fly or had one
of those three day courses, there's your problem! You never learned
to launch correctly.
3. I like to twirl around with my wing tip touching the ground
and I need lots of power to do that. Yeah, what ever, have fun,
try not to kill yourself, OK?
Are there any good reasons for having more power? You bet!
1. You're a big dude. The bigger you are the more power you need.
When you're over 200 pounds it will be more likely that you'll need
2. I will normally launch from a high altitude site. High altitude
is thin air, thin air needs more power. Altitude isn't too much
of an issue till you get to 5 to 6 thousand feet. If your launch
is above 8 thousand feet the big boy motors may be your best choice.
The thickness of the air is called your density altitude. It's a
big fancy word. What makes your density altitude higher, (or air
thinner) high take off areas, hot days and lots of humidity. you
need more power in these situations. Cool days at sea level need
3. I bought a piece of junk, uncertified, mystery wing from Ebay
and it has a sink rate like a ton of bricks. Alas, so many pilots
get their priorities backward. After spending a lot of money on
a motor they get the cheapest wing they can find. The sink rate
of the wing makes a lot of difference to the climb rate of the craft.
You'll need a lot more power to get a crappy old wing going. But,
this is not the important part, your wing is the most important
piece of equipment you will buy. ITS WHAT FLYS! You don't want to
be in the air with something that flys poorly.
4. Damn it! I like power! Well, that's cool. You should get what
So why wouldn't a person get as much power as they can get, after
all you don't need to use it. Why get less when you can get more?
Mainly because there are other issues to consider. The most powerful
motors are the heaviest. Some are close to twenty pounds heavier
than a motor that would work fine for you. More weight is harder
to run with and harder to land. It's harder to haul around, harder
to get out of your car. If you've had any issues with your back,
you should be looking for the lightest motor that you can get your
200fpm climb rate with.
This year three of my students hurt their backs with their large
powerful motors and had to takes months off to rest up. All three
had a history of back problems and yet did not bring this up when
we were discussing which motors they should get. If you have a healthy
back, chances are you will have no problems. If you don't, don't
be shy, bring it up.
I have a history of back problems and eventually had to have surgery.
I now fly with wheels. if I had life to do over I would have started
flying with wheels. If you got a bad back do yourself a favor, fly
light or fly wheels.
Another great reason to sacrifice power is, if you can make you
motor quieter, do so! The greatest threat to our continued enjoyment
of this sport is noise complaints from the general public. Nobody
cares if we fly, but people do get annoyed by noise especially when
they are outside enjoying a day off. Currently only one model has
gone full out on the noise issue. Hopefully other will do so soon.
We can help by asking for quite motors and rewarding those companies
that respond with our business.