Hang Angle

Danough

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Hi guys,

Can someone explain to me the difference between these two methods of adjusting hang angle; changing the hang point vs adjusting the actual weight i.e. moving the fuel tank?

Thanks a lot!

Dan in Chattanooga
Dominator/582/Skywheels
 

ultracruiser41

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most would change the position of the rotor head. Adding weight is never a good thing.
 

Danough

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Thanks Ultra. What I’m trying to understand is for example this; If I have excess weight on the nosewheel, changing the hangpoint would not change the nosewheel weight much would it? Repositioning actual weight (not adding weight) would seem to do more toward reducing the actual nose weight I think.

This would also serve to change the hang angle, so my big question is in terms of flight characteristics is what’s the difference?

Danough
 

Vance

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In my opinion when flying a gyroplane the center of gravity in relationship to the rotor head is important.

A gyroplane that flies nose up or nose down tends to be less stable than one that flies nearer level.

In my opinion when flying a gyroplane the thrust line in relation to the vertical center of gravity is important.

A high thrust line in relation to the center of gravity tends to make the gyroplane pitch down under power and pitch up when power is removed. I do not consider this a stable response.

A low thrust line in relationship in relationship to the vertical center of gravity tends to make the gyroplane pitch nose up when power is added and nose down when power is removed. Many consider this a stable response.

I prefer a gyroplane nearer to centerline thrust with no power/pitch coupling.

In my opinion when on the takeoff roll the weight on the front wheel is important. Not enough weight on the front wheel will make the gyroplane try to lift off prematurely.

Your flight instructor should be able to help you set up your gyroplane and transition you into it.

I am not an aeronautical engineer.
 
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Danough

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Thank-you Vance. I will definitely be using my amazing flight instructor to help me with this and he is very capable. There had been a lot of emphasis on this list about hang angle (and rightly so), I’m just wondering if there should be more on nose weight or weight and balance if you want to use that term. Are they different animals? What should the nose weight be on a single seat gyro?

Danough
 

Vance

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I have flown gyroplanes without enough weight on the nose and I find them more challenging to make an elegant takeoff.

Too much weight on the nose is not a happy place for me either.

In my opinion weight on the front wheel is only remotely related to rotor head placement and more closely related to the placement of the mains.

I have heard people more knowledgeable than me say a hundred pounds on the nose is a good place to start for a single place with the pilot and full fuel.

I do not have enough experience to recommend a specific weight on the nose.

I suspect the ideal weight varies with the design.

When I road raced motorcycles we would start with a setup that worked for others and modify it for my personal style.

I have found this works well in aviation and generally straying too far from what most are using is a mistake.

I feel weight and balance is a complex subject and I feel it is best to address it with specifics rather than hypothetical challenges.

For example a gyroplane with a free castering nose wheel might do well with more weight than one with linked nose wheel steering.

In my experience gyroplanes do not all fly the same and gyroplane pilots do not all like the same setup.
 
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Jean Claude

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To explain simply, you must look the main forces. There is
1) rotor thrust, in the axis of the cone traveled by the blades
2) driving thrust, in the axis of the propeller
3) parasitic drag of the airframe, which decreases the driving thrust
4) gyrocopter weight applied to the center of gravity

In level flight, these four forces are balanced as in Figure

Sans titre1.png

You can see that the level center of gravity is in front of the rotor attachment point, due to the angle of attack of the disk.
If the center of gravity is further back, then the same angle of attack of the disc will require an airframe more nose up despite level flight
If the center of gravity is further in front, then the same angle of attack of the disc will require an airframe more nose down during the level flight.

This has little effect on the drag of the airframe, but on landing, it changes the height of the wheels relative to the ground.
In addition, the stops of the stick being attached to the structure, can excessively limit the control.

Regarding now the position of the wheels, it is appropriate that the front wheel does not rise too early, when the rotor is full nose up. This determines the load distribution between the front and rear wheels

Sans titre.png
 
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Danough

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Thanks guys. Here is my simplified take away from your responses and others. Hang angle is very important in flight and is adjusted by the rotorhead position. Distribution of weight between nosewheel and mains is less important in flight but is adjusted by the position of the mains.

If the nose rises late during takeoff because of excessive nose weight, it’s probably ok to fly if the hang angle is correct.

Danough
 

Brian Jackson

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From what ive learned in my build as a non pilot currently, nosewheel weight for a single seater should be around 30~40 lbs. Pulling the mains back too far to increase nosewheel weight may increase takeoff roll substantially. Seat height and rotor height make a huge difference in CLT target. Fore/aft rotorhead location fine-adjusts hang angle, but proper weight distribution in the design should be first priority, then adjust rotorhead accordingly.
 

Danough

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Yeah my nose weight with me (190 lbs) & 1/2 fuel on my Dominator is 110 lbs. 30 mph and 250 rotor rpm with full back stick and nose wheel is still on the ground. No way to adjust the mains.
 

Vance

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There is always a way to adjust the mains and the weight on the nose.

The gyroplane I fly (The Predator, a two place tandem) lifts of at around 48kts. The nose comes up around 200 rotor rpm and she lifts off somewhere around 300 rotor rpm.

I don't look at the indicated air speed the nose comes up because I am busy with keeping her on the center line, balancing on the mains and advancing the throttle smoothly.

Get someone with Dominator experience to fly your aircraft.

In my opinion you are putting you and your gyroplane at risk by making this sort of test when you don’t know how to fly.

I feel flying is not something you can sneak up on.

Bad outcomes happen quickly in anything that flies.

Please take this as it is written.

It is not intended to be a condemnation of your skills.

I have just seen this story too many times.
 

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Danough

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Thanks for your advice and concern Vance. Instruction resumes as early as this week.
 

Jean Claude

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Can someone explain to me the difference between these two methods of adjusting hang angle; changing the hang point vs adjusting the actual weight i.e. moving the fuel tank?
Moving the fuel tank only will acts when it is full. When it will empty, the bad balance becomes again
 

jm-urbani

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In montelimar we have tried in reality two different main gear wheel positions ( on our home builts) ,

A/ wheels nearly under the rotor heard
B / wheels 25 cm (10 inches) behind the rotor head

in the A case the nose wheel lifts quickly and the pilot needs to anticipate this during take off pushing the stick ahead as soon as the nose wheel becomes ligther

in the B case the nose wheels lifts later but more violently

whe have modified case B giro coz we did not like the behaviour of this giro which appear to be more difficult to take off in

@ Dan,

please don't take it badly but IMHO a prototype must never be tuned and tested by an average pilot, at the end of the construction it must be verified and tuned by really experimented pilots who will often demand modifications.

let me tell you that my mate who has litterally thousands fligth hours has managed to nearly kill himself testing one configuration of the JYRO dta prototype in montelimar... then imagine a new pilot testing a prototype he built himself asking the kind of questions you are asking here (the question you are asking shows that you still have a couple of things to learn, don't take it badly please)

in my opinion it is the duty for the old pilots/builders to help young pilots/builders to check their gyros before tests and to test them

if you really do it yourself I strongly urge you to ask your instructor to train you juste before your tests the best drills being a lot of surprize low heigth engine off senariosto increase your chances to overcome crow hops ..

but remember it : if no instructor accepts test your gyro, this will be because you definitly must not fly it

my two cents and I may be tottaly wrong
 
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Jean Claude

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When the main wheels are too far back: the takeoff is abrupt and unbalanced in pitch (Fig. left)
When the main wheels are too far forward: the takeoff is easily balanced, but the the run is greater because the angle of attack of the disc is lower to balance (Fig. right)
1145103
JM is right: Experimenting with no mind to what will happen is dangerous.
 
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Gyro28866

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Some years back, I had a guy come asking me to test fly his gyro. It was a Bensen B-8 frame with a cabin built onto it, similar to a SportCopter pod. Everything "looked" correct and I did not do a hang test. My Bad! He claimed the guy he bought it from was 200'ish pounds and flew it all the time.
For the first test, I just wanted to balance on the mains. Went out and pre-rotated the rotor and began a slow run to bring the rotors up to speed. The machine did not have a rotor tach; so I was just eye balling it. The rotor come right up and stick in the full rear position. The rotor seemed to be at full flight speed and the nose was not getting light. I pushed it a little more and the mains got light and maybe even broke ground a little and the nosewheel never lifted. The nosewheel shimmy was pretty intense. A poodle pooping a peach seed could not have shook that hard.
Point is, the mains relationship to the CG is critical for ground handling and the rotors relationship is critical for stability and controllability in the air. When the machine is balanced on the mains, you are basically flying with your main tires still in contact with the ground; add more thrust and lift off.
I was lucky that I did not roll this machine up into a ball. I do not know what the nosewheel weight was, other than it was way too heavy.
 
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