# Passenger Weight Limitations in Glider

#### Terry_Smith

##### Gyroplane Fan
I'm not sure if I've ever read anything on this, but I was curious to find out what the max allowable weight would be for flying in a Gyro Glider. I realize the tow vehicle provides ample power for lift, but I also know the heavier the load, the more power is needed to lift the glider. And, I'm guessing the load available also depends on blade length. The last time I went up, it took about 10MPH more for me to get up than those not as "gravity challenged" in our group! (I'm working on that problem too). Any info would be appreciated. Thanks!

#### EI-GYRO

##### 21st Century Crankhandler
weight limit

weight limit

If you are a bit heavier than average, you could fit longer blades.
But you don't specify what blades are in use, or how long the runway is.

22 foot extruded aluminium blades should be sufficient for most weights at
sea level and reasonable temps.

As for the airframe load, it is designed to carry an engine also, so unless you
weigh 150 pounds above average, you should be OK.

For an average weight guy, I would advocate some ballast in any event.
You don't want the glider to be too 'floaty'.

Hope this helps.

#### PW_Plack

##### Active Member
Terry, if you could measure rotor RPM, all-up weight and density altitude on a given run, some max numbers could be worked out by calculating rotor tip speed.

The Bensen/Brock blades were pitched to turn faster than some newer blades, and probably spin at close to 400 RPM with 400 pounds of people in the glider. If someone in the area has an optical tach, or you could rig a bicycle speedometer temporarily for testing, you'd have a starting point.

Once you know the baseline, you'd need to determine what redline RPM is for the blades. Then the formulas could allow you to work backward to get a max load for any given density altitude.

#### okikuma

##### Member
Terry,

I've wondered that myself because I don't ever recall an official gross weight limit listed for a gyro-glider.

That being said, I reason that one shouldn't exceed the gross weight limit set for equivalent powered machine based on the same airframe (i.e. Brock or Bensen).

Originally, the Brock KB-2 with a 23' diameter rotor disk was listed as 240 lb empty weight and a 600 lb max gross weight. That works out to 260 lb useful load. If a Brock KB-2G gyro-glider weighed in nominally at 120 lb empty (just a guess) and with the identical 23' diameter rotor disk, that works out to be 480 lb useful load for a 120 lb gyro-glider.

I'm guessing that the Chapter 1 gyro-glider has a 23' diameter rotor disk. That works out to be 415.5 sq ft of disk area. If the gyro-glider was flown at a gross weight of 600 lb, then the rotor disk would be operating at a 1.44 lb/sq ft disk load. A respectable value.

Perhaps at the next meeting, bring three bathroom scales and weigh the gyro-glider to obtain it's actual empty weight, ready to fly. Bring 20 - 25 lb of weights to calibrate each scale prior. With one scale under each main tire, and the third under the tail (because it sits on the tail when empty), the sum of all three weights will show the actual empty weight of the gyro-glider.

Wayne

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#### Terry_Smith

##### Gyroplane Fan
Paul, Wayne - thanks for the info. I'll see if we can get some scales to bring to the meeting since we plan on using the Glider. I felt that it would be a good idea just to know what our Glider's limitations are. We'll also verify the rotor disk diameter also.

#### Terry_Smith

##### Gyroplane Fan
Wayne, Well, we FINALLY weighed the glider (the floor was not quite level) and came up with 145 pounds for the glider, and the glider actually has a 2ft hub bar, giving us 22' diameter rotor disk - which (if I'm right) is 380.1 sq ft, or 1.58 lb/sq ft disk load (at 600 pounds). Since I'm still learning (and will probably NEVER stop), curious how that number looks to you.

#### okikuma

##### Member
Hi Terry,

Sorry I missed this post.

Yeah, 1.58 lb/sq disk load is fine. Well within the capabilities of a 22 foot diameter rotor disk. With an equivalent gross weight of a powered KB2 of 600 lb., and the known empty weight of 145 lb. gives the gyro-glider a 455 lb. useful load. This opens up to a larger combination of student/instructor weights.

Wayne

#### Terry_Smith

##### Gyroplane Fan
Wayne,

Thanks. We may decide to go with a slightly lower limit just to be on the safe side, but as you said, it will allow a variety of pilot/student weights. Right now, we're limited to 1 pilot who is capable, but hopefully that will change as people get more comfortable and we can share duties. All in time!

#### okikuma

##### Member
Using a lower set gross weight is not a bad idea for the 22 ft diameter rotor disk.

An alternative would be to increase the disk to 23 ft and bring the disk load down to 1.44 lb/sq ft. for a 600 lb gross weight.

I'd like to hear from those who have regularly flown a two seat gyro-glider for training. What was the maximum gross weight for your particular glider?

Wayne