Why is ultralight weight so hard to make with a gyro?

GrantR

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Why is ultra light so hard to make with a gyro?

Check out this glider:
http://home.att.net/~m-sandlin/goat_design.htm

The wing weights 35 to 42 pounds same as dragon wings. Empty weight is 135#.

MZ 34 is 42# with 30hp.

So this would weight 177# empty with a MZ 34. Seems like a gyro could be built just as light. Realistically say 200# ready to fly
 

GyroDoug

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Grant,

A Gyroplane is not a very efficient aircraft. They are very draggy and are going to take more power to push through the air than an equivalent fixed wing ultralight would. A very lightly built Gyro with a 40 HP engine will fly a smaller pilot at lower altitudes with marginal performance. That can be done if you want it bad enough and hit legal ultralight weight. However, you will have lots of limitations, like no pre-rotator, no brakes, no instruments, marginal power, and restrictive payload (i.e. smaller pilot) and low altitude capability.

While someone could shave some weight off by using high tech materials (like carbon fiber) and a really high power to weight ratio engine could be used (like the AIXRO 50), those items are going to be way more expensive than the standard options and defeats one of the major draws of ultralights which is lower complexity and lower cost. With the advances in technology available today I have no doubt a good performing ultralight Gyro could be built but by it's very nature it will be a bare bones (basic) Gyro and it will be expensive to build and require more knowledge, more skills and more time to develop than just going with the status quot.

I hope with all my heart that someone will develop that kind of a machine as I believe there is a market for a good ultralight Gyro. But not only does it have to be good, but it has to be cheap enough to sell or it will never make it. I wish someone all the luck.
 

Passin' Thru

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Grant, it’s doable.
The basic Bensen B-7M with the Nelson engine and wooden blades weighed 180 pounds. That’s 70 pounds below legal ultra light spec.
The basic square tube Bensen B-8M with the mighty Mac engine, modern offset gimbal head and heavy stock ox cart wheels weighs 250 pounds and can be made considerably lighter.
As Doug said above, folks don’t stick to basics, they want more fancy stuff and fancy stuff weighs more! Pretty wheels, prerotator, fancy differential braking, a full instrument pod. In most instances they don’t know how strong something is and how strong it actually needs to be. So they decide to “beef up” this and that.:suspicious:
Everything weighs something and it adds up fast.:yo:
 

Redbaron

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I agree, if you want it ultralight weight you need to weight everything as you build it, ounces do add up to pounds! danmcgee said his bumblebee weighs around 230 sumthin pounds! use plastic wheel not aluminum, get creative with the tail to make it light but strong! consider straping all your guages to your leg! If you wanna add a luxury item throw it in the air if it hits the ground leave it off!:peace:
 

chuter

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I believe Chuck Beaty's gyro is significantly below ultralight max weight, and he says it performs very well.

503 Rotax with prerotator and brakes.

There are pics of it on the forum but I don't have a link for you right now.

So it's possible. I tried with 2 different tractor fuselages and didn't make it, so I gave in and just loaded it up with a bigger motor and lots of gauges and other stuff and went the experimental route.
 

gyromike

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I believe Chuck Beaty's gyro is significantly below ultralight max weight, and he says it performs very well.

503 Rotax with prerotator and brakes.

It sure does perform well.
If I remember correctly, he said it weighed 240 lbs.

Here's a picture of me about to take it for a spin:
 

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C. Beaty

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240 lbs, Mike, before Kosala installed those Air Command fuel tanks. They may have taken it over the limit.

The original fuel tank was a fiberglass unit tucked under the motor mount rail that developed a drip after 10 years.
 

C. Beaty

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You know, Brian, I once had a stick of filament wound fiberglass pipe that I looked at long and hard for a gyro airframe.

The stuff is made for underground petroleum lines.

I think it was made by AO Smith but probably comes from China now.
 

SnoBird

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It sure does perform well. If I remember correctly, he said it weighed 240 lbs.Here's a picture of me about to take it for a spin:

That's a brilliant design, highly efficient and optimized - probably the best out there. The only one that gives it a run for its money are Wallis machines. Odd that so few of each design are built and flown by others.
 

Friendly

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Chuck,
how does the round tubing compare to the square as far as the mast goes?
 

C. Beaty

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Being fairly well triangulated, Mark, it’s way too stiff for a 2 blade rotor.

I fought a no win battle with 2/rev until I came up with the slider. That’s what the drag hinges were all about.
 

C. Beaty

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Not if triangulated, Mark.

My first gyro was made from round 2½ inch x 0.120 wall 2024 tube, unbraced and dimensioned to Bensen plans.

It was perhaps the most vibration free gyro I’ve ever flown so there is an advantage to round tube with equal stiffness in all directions.

I got my first set of Hughes 269 blades from an elderly gentleman that had sawn a taper in the blade root ends to make them look like Bensen metal blades.

The in-plane strength looked a little weak so my first experiment with drag hinges and a door hinge hub were on that machine. It was glass smooth, making me think that it would work on the present machine. But it didn’t.

Arthur Young, the designer of the Bell-47 had encountered the exact same problem in the 1940s and had solved it the same way; engine, transmission assembly mounted on very soft rubber biscuits and initially, with external bracing on the rotor to stiffen it in-plane.
 

WHY

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Hi Chuck

In regard to your post #16, you mentioned your "slider" hub. What would you estimate the amount of movement that takes place here to reduce the two/per rev problem. I'm guessing the amount varies from a light gyro to a heavy gyro.

Tony
 

C. Beaty

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The movement, judging from the scrub pattern on the pivots is quite close to zero; perhaps 1/16 inch.

The intent is tuning and contrary to what one might expect, softening the rotorhead mount raises the in-plane resonant frequency of the rotor. The object is to get the in-plane resonance above 1/rev. This shows up as a 2/rev shake because of the frequency doubling effect of rotor rotation.
 
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