First Stupid Question - 103 Weight

Go for Broke

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New guy here.

I've trolled everything I can find about Gyros. It appears that it is rather difficult to get any Gyro, safely under the Part 103 limit.

Then I come across the Justsolo103 Ultralight (https://justaircraft.com/just103/). Seems to have everything you could want in an Ultralight/Aircraft.

FIND QUESTION HERE: Is there something inherent in the rotary design that makes them heavier than a fixed wing?

Or, have I just missed something altogether?

Thanks in advance,
 

ultracruiser41

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It can be done.....it's hard to do it....but I've actually seen a few real ultralight gyros.
Remember.....just because something says it's an ultralight....doesn't mean it's easy to fly.....many heavier aircraft handle much better. Ultralight is an aircraft built to meet a weight specification.....doesn't mean it's easy or safe to fly.

There are ultralight gyros out there....some give up good handling characteristics to meet weight. Some fly well.....but nothing beats good training.
 

Gyro_Kai

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I believe the issue is, that gyros generally need a bigger engine (more hp), which means, high motor weight, more stable motor mount etc.. This drawback needs to be caught up with even lighter construction around.

Kai.
 

BEN S

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I see it more as a money issue. If you wanted to build a rig from titanium and carbon fiber with epoxied trusses instead of nuts and bolts yeah you could meet the weight safely and with good performance. It might cost you 100K but it is doable
 

Jazzenjohn

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The biggest problem with people staying under the 103 weight limit is, Doing the same thing but expecting a different result, overbuilding, And not paying any attention to weight as it is being built. A perfect example is the prop. Warp drive props are fantastic props, great value for money, Good thrust, and the most damage resistant available. They are also by far the heaviest prop commonly used. Putting a 3 blade Warp drive prop on is like adding an additional 10 or more pounds compared to a wood or Powerfin prop. I'm not saying it is impossible to build a legal ultralight with a Warp drive prop, but you must save it somewhere else. Skywheels are reportedly fantastic rotors. They are also heavy as hell. Again, I'm not saying it is impossible to build a legal ultralight with Skywheels, but where are you saving the extra weight to pay for them?
If you build a Bee or a Hornet or a KB-3 with a 503, use Dragon Wings and a cordless drill motor or Brushless motor prerotator or Bensen blades and hand start them, use a Powerfin or wood prop, and use Azusa plastic wheels, and a tube and fabric or other lightweight tail, you'll have no problem with weight.
If you want to go exotic like a Titanium frame and carbon fiber parts, the sky's the limit as to cost, but, having actually built a Titanium frame ultralight gyro myself with a 4 stroke HKS engine, the 100K number is rather high. I spent less than 20% of that including everything.
 

gyrojake

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The biggest problem with people staying under the 103 weight limit is, Doing the same thing but expecting a different result, overbuilding, And not paying any attention to weight as it is being built. A perfect example is the prop. Warp drive props are fantastic props, great value for money, Good thrust, and the most damage resistant available. They are also by far the heaviest prop commonly used. Putting a 3 blade Warp drive prop on is like adding an additional 10 or more pounds compared to a wood or Powerfin prop. I'm not saying it is impossible to build a legal ultralight with a Warp drive prop, but you must save it somewhere else. Skywheels are reportedly fantastic rotors. They are also heavy as hell. Again, I'm not saying it is impossible to build a legal ultralight with Skywheels, but where are you saving the extra weight to pay for them?
If you build a Bee or a Hornet or a KB-3 with a 503, use Dragon Wings and a cordless drill motor or Brushless motor prerotator or Bensen blades and hand start them, use a Powerfin or wood prop, and use Azusa plastic wheels, and a tube and fabric or other lightweight tail, you'll have no problem with weight.
If you want to go exotic like a Titanium frame and carbon fiber parts, the sky's the limit as to cost, but, having actually built a Titanium frame ultralight gyro myself with a 4 stroke HKS engine, the 100K number is rather high. I spent less than 20% of that including everything.

Perfect answer.
Bensen / Brock blades hand start very easy also.
 

Go for Broke

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41 - Training...GOOOOOD!

Kai - Justsolo103 uses: https://www.polinithor.com/en/polini-thor-250-thor-250-ds-2/ @ 18kg for 36.5 HP.
Rotax 447 27+kg for 39.6 HP.https://www.rotaxservice.com/rotax_engines/rotax_447ULs.htm.

Ben - See John's answer...titanium...COOL!

John - Titanium...COOL! All the other stuff seems to be right on target for getting the weight right.

Jake - Thanks for the second.

ALL - Is it possible that the rotor head up is the major source of the weight difference between rotary and fixed wing 103?
 

jany77

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Just for some weight comparison
bensen rotor head no prerotator ring or prerotator it self include check plates is 10 lbs
22' dragon wings are 41 lbs ( I weight one set my self at late Martin Hollmann's office )
22' sportcopter are 46 lbs based on weight given by sportcopter
 

Go for Broke

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John - Could you point me towards more information about "cordless drill" pre-rotators? I've heard of it but have never seen so much as a blurry picture of it. And, how is a "brush-less" motor different or better than a "brush" motor in this application?

Also, you mention the Benson blades and hand start. Is there something about the Benson's that are special for hand start that other blades lack?
 

Jazzenjohn

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I'm not sure who here came up with the cordless drill prerotator, Possibly Dave M, but they basically used a cordless drill motor with an adapter that fit into the regular bendix commonly found on single place gyros. It may have been a 1/2 drive socket but in any case it is a square drive, so, not too difficult. You would assume the typical bendix ring gear combos have a 12-1 ratio and find a drill driver that matched it. for 140 RRPM you'd need a drill motor that spun a little higher than 140*12 or 1680 so maybe 2000 rpm. 140 would require about 900 Watts or so based on the numbers I came up with here: https://www.rotaryforum.com/threads/prerotator-power-required-vs-rrpm.35360/#post-912761 This is, I believe, the lightest solution for an Ultralight Gyro because the drill motor, even if carried with you, would not be counted weight.
The difference between a brushed and a brushless motor is, well, brushes. Brushes deliver the current to the armature and tend to be much better at Zero RPM and low speed torque. Brushless motors Generally have better magnets, power to weight, and are higher efficiency, but they have poorer zero and low speed performance. For someone who must have a rapid spin up from Zero RPM, Brushed motors are a better fit. For those who can give the blades a push and like to taxi with blades running, or who want the maximum performance at the minimum weight, brushless is hard to beat.

Dragon Wings have a twist to the blades that make them much more difficult to hand start. Blades without the twist are easier. Very very few people hand start their blades. I've seen 1 guy able to hand start Dragon wings once. It's nice to know how and to be able to hand start your blades (Not DW's), but I think there are better options now.
 

BEN S

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DW's are a bear to handstart. But I hand started my Sportcopter blades for about 3 years before upgrading to a pre-rotator. You just had to be really careful not to poke your eye out on the Pitot Tube while facing the mast!
I once saw a Vancraft frame hanging on a wall that had a hand crank for a pre-rotator, owner said his dad made it and it worked, was very light, but a cordless drill would probably be better.
 

Barney Bahle

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Dave McCutchen turned me on to the drill motor prerotator. I had an upper unit from a Wunderlich prerotator http://www.calumetmanufacturing.com/prerotors.htm . This picture has a cable attached but you leave that off. The cable end is 1/2 inch square drive so you need a 1/2 inch socket adapter and a good high torque cordless drill. Like John said, since the weight of the drill doesn't count it has to be the lightest prerotator going.

I don't recall the numbers, maybe 120ish, but I know David had Bensen blades and could get more RPM with his than we could get out of my heavier Phoenix extruded blades. Maybe not the best thing going but it beats hand patting.
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