Design by the Numbers?

The ease with which a gyro can be made to fly deludes designers into thinking they are good designers and customers into thinking the designer knows what he is doing.
So true Jim.
Wen i first started i believed the gyro i had [ HTL W/O a HS] was 'stable'.
I soon realised it was not stable but very controlable.
And as you point out, there isa BIG difference.

The thought of a $30,000 engine in a gyro makes me a little nauseous..
A 30K donk helps me relax abit more CB.

my first machine that I built that would tote me alof was the skypup chuck. not counting the single cylinder 28 hp hirth engine that gave me 2 engine failures, I only had around 2500 dollars in the whole deal. YouTube - Me taking off in my skypup ultralight

C. Beaty said:

Mike, I have fond memories of a time when I bought 35 shot down Mac target drone engines, mostly in bushel baskets, for $250. I got about a half dozen good engines out of the lot and a lifetime supply of good cylinders.

The thought of a $30,000 engine in a gyro makes me a little nauseous..

Click to expand...

A Mac wasn’t all that bad once we’d learned the tricks of keeping it alive.

In those early days though, we’d simply fly until the Mac seized up. It was a little scary the first time I landed with the engine still running.

lol thats funny right there I don't care who you are.

C. Beaty said:

A Mac wasn’t all that bad once we’d learned the tricks of keeping it alive.

In those early days though, we’d simply fly until the Mac seized up. It was a little scary the first time I landed with the engine still running.

Click to expand...

C. Beaty said:

A Mac wasn’t all that bad once we’d learned the tricks of keeping it alive.

In those early days though, we’d simply fly until the Mac seized up. It was a little scary the first time I landed with the engine still running.

Click to expand...

A high light of my early Mac experience was learning that you could actually keep one in the air long enough to run out of gas!

pete, I heard from a past thread you taught chuck the stabilizing effect of the offset gimble head. got any pics from the glory days?

Passin' Thru said:

A high light of my early Mac experience was learning that you could actually keep one in the air long enough to run out of gas!

Click to expand...

More numbers please?
Is it possible a numeric analysis of rotor head angles? Also the "window" of movement of rotor blades?
thanks
Heron

Doug,
Would you undertake such a project, if the funds or equipment were available?

I agree good thread heron. numbers usually dont lie. Are there any youtube clips of a pio in action, I saw video of an raf with no stab and a classic aircommand with a small stab bobbing but wasn't sure if it was real pio. when I say pio I mean the rotor loading or unloading and the thrustline bobbing the gyro.

Heron said:

More numbers please?
Is it possible a numeric analysis of rotor head angles? Also the "window" of movement of rotor blades?
thanks
Heron

Click to expand...

I would like to see a front/back and side to side quadrant of rotorhead moving angles.
Also something like a pizza quarter showing rotor tip range of motion. (in front)
thanks
Heron

I would like to see a front/back and side to side quadrant of rotorhead moving angles.
Also something like a pizza quarter showing rotor tip range of motion. (in front)

Click to expand...

The program I featured in this thread
http://www.rotaryforum.com/forum/showthread.php?t=28419
calculates the one and two per rev flapping angles for steady state flight based on naca report 716 for mu values between 0.07 and 0.4. The coefficients are a1,a2 for longitudinal flapping and b1,b2 for lateral flapping. You find them at the end of the output listing. The flapping angle around the disk is then:

beta= a1*cos(psi) + a2*cos(2*psi) + b1*sin(psi) + b2*cos(2*psi)

where psi is the blade azimuth angle with zero beeing over the tail of the aircraft. You can easily plot this in octave or a spreadsheet.
Note that these angles are for a trimmed flight state where the rotor thrust passes through the CofG and no resultant moment is acting on the plane that has to be balanced by the rotor.
If you want flapping angles during maneuvers things get much more involved.

Mark:

I'd be happy to help on the "flying dump truck" project, time permitting.

There are major parts of it that involve knowledge I don't have. I used to drive a dump truck, and I played with simple strain guages and direct-reading Wheatstone bridges, back in Engin. lab.

I am digitally illiterate, though, knowing nothing about other forms of off-the-shelf transducers and data recorders. We'd need these things to record RRPM, rotor flapping angle, spindle angle and rotor thrust over very short time intervals -- on the order of every 0.01 second. Stuff happens fast in PPO (or PPO-stopping) event sequences! We'd need people who work with equipment of this sort. I know there are folks on this Forum who do.

Somebody would have to build a rotorhead upper unit (bearing housing, towers and a thick spindle bolt), preferably out of steel. The familiar aluminum version might not survive one or more blade-busts.

I would think the single biggest hurdle would be getting the manufacturers to donate multiple sets of blades -- some of which would certainly get trashed.

Natural Selection ~or~ Beginning with Basics

Natural Selection ~or~ Beginning with Basics

Since the beginning of time, all advancements have been based on the evolutionary 'survival of the fittest'.

Those that hold this observable Darwinian position must then ask why there is nothing in nature that represents a rotating airfoil with the ability to move latterly within its environment. Not even the maple seed.

Vertical descent, can be complimented by vertical ascent if power is applied. Perhaps the Chinese were the first to achieve it.



Two things are obvious from the above sketch.

One is that the inner radii of the rotating-wing will not experience the same air velocity as the outer radii. This is the first disadvantage of the rotating-wing when compared to a fixed-wing.

The second thing is that the Chinese rotor has; rigid blades, no teetering hinge, no gimbal, and a low center-of-gravity.


The problems now start to get greatly exacerbated when man starts to push this rotary-wing horizontally. The discussion of Bensen's gyrocopter has not significantly change in the past decade, or two, or three.

IMHO, it is time to re-look at the natures maple seed and consider the various means of providing it with another Darwinian feature. Namely, all living creatures and all of man's successful vehicles have bilateral symmetry.


Just a small, non-provocative comment.
Dave

Dave. When I was a kid , I would take nature's single rotor maple seed , glue two of them together at the root on a balsa wood shaft and drop them out of trees. They auto-rotated pretty good. Looked something like the Chinese model. But I preferred powered flight so I turned to nature's fixed wing department.

Which of course are the moths that would flutter around the porch light at night. Talk about unstable flight. I would gather a bunch of them in a jar , bring them in the house , very carefully cut a bit off the wings , it was cool , I had an active airport in my mom's living room.

The moths could barely fly with clipped wings, so they would taxi along the floor to get airborne and then do about 10 smooth circuits around the living room to get to the light on the ceiling. Then they would drop to the floor and start over. The trick was to clip a bit extra off one wing so they all flew a left hand circuit.

Arnie..

Arnie..

You sick bastard!
Ben S

Arnie reminded me of a summer morning when I was young….grandpa and I was walking out to the barn when a Piper-Cub flew low over us. I excitedly told him I loved aircraft, especially helicopters, though I never saw a real one fly…just pictures. He gave me that ornery grin and said he could make a straw go straight up like a helicopter and of course I said show me, show me, etc.

On the side of the barn were gobs of horseflies warming up in the sun. He picked up a straw about 4" long, reached over and picked off a horsefly and stuck the straw up its rear-end. He let the assembly go and it went straight up and out of sight…never to be seen again. I thought that was so cool….I still miss him.

My ol man reconed he used to catch crows in the old chookhouse, tye 2 together with strin n let um go............... .

If he only caught one, he'd punch a small hole ina small pice of cardboard n shove the crows head through it and .................. .

Needless to say, he never had them crows stealn eggs from our chooks.

Is chook Australian for chicken?

When I was a boy, I used to drill a hole in a kernel of corn (maize), tie a long string to it and lower from the top of the roof and wait until a chicken swallowed it. I could hoist the chicken nearly to the rooftop before it pulled out of its craw.

They never learned; the same chicken would repeatedly swallow the corn kernel and get hauled up.

Gyro “designers” are about like chickens.

When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge of it is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced it to the stage of science. –Lord Kelvin