- Thread starter Terry_Smith
- Start date

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.

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.

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

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

Last edited:

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

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!

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