Dyna Beads - Do they work? If so, how?

[mcatrophy]

Lift depends on airspeed, thrust on change of momentum of air through propeller/jet. Speed of ground/conveyor belt/aircraft carrier just determines the starting airspeed of the plane.

I suppose if the "ground" was travelling backwards at a couple of hundred mph, initial thrust would be reduced, but if it was sufficient to start the plane moving relative to the "ground", it would be sufficient to get to take-off speed. So long as the conveyor belt was long enough.

ON TOPIC (?) Of course, the wheels would need to rotate faster than usual so would need careful balancing. Or beads (if they work).

 

[HotRodZilla]

Ok...So why won't 2oz of water, oil, milk, whatever, work the same way. Hell, maybe we're stumbling on a new, valid use for Mercury.

 

[Fred W]

Mercury was one of the original dynamic balancers but was abandoned for obvious health reasons. Antifreeze is another commonly used liquid.

 

[PhilJet09]

Lift depends on airspeed, thrust on change of momentum of air through propeller/jet. Speed of ground/conveyor belt/aircraft carrier just determines the starting airspeed of the plane.I suppose if the "ground" was travelling backwards at a couple of hundred mph, initial thrust would be reduced, but if it was sufficient to start the plane moving relative to the "ground", it would be sufficient to get to take-off speed. So long as the conveyor belt was long enough.

ON TOPIC (?) Of course, the wheels would need to rotate faster than usual so would need careful balancing. Or beads (if they work).

In this case, any plane needs only to overcome the friction created at the axle, from/through the wheel bearings. Aircraft wheels are not driven, they turn as freely as their wheel bearings will allow (let's ignore wheel spin-down systems on certain aircraft for the moment). The engine/s will pull the plane forward through the AIR once that is achieved. The only real limiting factor is the max tire speed for that particular aircraft. In my G450, that happens to be 195 knots. So, as long as the belt is moving slow enough that it's speed, plus my forward speed is less than that, there should be no problems getting off the ground. But there in lies the rub. My jet rotates at about 125 knots (for average weights). That's 125 kts through the AIR (regardless of what the conveyor belt is doing), which is easily achieved after the 27,600 pounds of thrust I have available over comes the friction through the wheels. But, if the belt were moving backwards at more than 70 kts, I would exceed my maximum tire speed and bad things could happen. So...this experiment isn't really scale-able to larger aircraft if you want the belt speed to match or exceed rotation speed. Little aircraft are fine, because you can easily double their rotation speed without exceeding the capabilities of the tires.

 

[mcatrophy]

Lift depends on airspeed, thrust on change of momentum of air through propeller/jet. Speed of ground/conveyor belt/aircraft carrier just determines the starting airspeed of the plane.

I suppose if the "ground" was travelling backwards at a couple of hundred mph, initial thrust would be reduced, but if it was sufficient to start the plane moving relative to the "ground", it would be sufficient to get to take-off speed. So long as the conveyor belt was long enough.

ON TOPIC (?) Of course, the wheels would need to rotate faster than usual so would need careful balancing. Or beads (if they work).

...The only real limiting factor is the max tire speed for that particular aircraft. ...

I hadn't taken that into account in my simple thought experiment

. Will try to do better next time

.

Out of interest, are you quoted a maximum tail-wind that you can start the engines in? Over a certain value they won't run (I used to work for Rolls-Royce as an electronics engineer, so I know a little about them).

 

[timk]

The one reason I discontinued using them was whenchecking tire pressures one day,one of the beads got stuck in the valve stem and de-flated my tire. Good thing I was home! The airsoft ammo sounds promising because of their larger size.i THOUGHT they worked pretty well. Aren't lead weighted tires supposed to be re-ballanced at their half life?

 

[Fred W]

Aren't lead weighted tires supposed to be re-ballanced at their half life?

I have never felt a need to do that, nor have I ever developed any symptoms of imbalance on a previously balanced wheel (unless a weight was thrown.)

The inequity of weight on the new tire would be in the tire's carcass, not in its tread rubber. Theoretically the peripheral tread will wear uniformly around the tire circumference and remain in balance. The exception would be if the wheel was out of balance and bouncing down the road, then the rubber may be worn away unequally and exacerbate the imbalance over time.

 

[yamafitter]

Aren't lead weighted tires supposed to be re-balanced at their half life?

I have never felt a need to do that, nor have I ever developed any symptoms of imbalance on a previously balanced wheel (unless a weight was thrown.)

The inequity of weight on the new tire would be in the tire's carcass, not in its tread rubber. Theoretically the peripheral tread will wear uniformly around the tire circumference and remain in balance. The exception would be if the wheel was out of balance and bouncing down the road, then the rubber may be worn away unequally and exacerbate the imbalance over time.

Most lead is radiologically stable and does not decay. Now if you needed more weight and were using uranium (238U) then the uranium will decay in a series of steps culminating in lead (206Pb), a decay rate with a half-life of roughly 4.46 x 109 years at which time you should rebalance your tire.

Only Gen 1 owners need to worry about this since they are the only ones that will never have the common sense to upgrade their scoot.

 

[PhilJet09]

Lift depends on airspeed, thrust on change of momentum of air through propeller/jet. Speed of ground/conveyor belt/aircraft carrier just determines the starting airspeed of the plane.

I suppose if the "ground" was travelling backwards at a couple of hundred mph, initial thrust would be reduced, but if it was sufficient to start the plane moving relative to the "ground", it would be sufficient to get to take-off speed. So long as the conveyor belt was long enough.

ON TOPIC (?) Of course, the wheels would need to rotate faster than usual so would need careful balancing. Or beads (if they work).

...The only real limiting factor is the max tire speed for that particular aircraft. ...

I hadn't taken that into account in my simple thought experiment:fool: . Will try to do better next time:mda: .

Out of interest, are you quoted a maximum tail-wind that you can start the engines in? Over a certain value they won't run (I used to work for Rolls-Royce as an electronics engineer, so I know a little about them).

25kts for the G450 and only 10kts for the CE680. That's the limitation anyway, they don't actually say in the manual it won't start, just that you shouldn't. It'd be interesting to know what the real number is.

 

[RossKean]

Aren't lead weighted tires supposed to be re-balanced at their half life?

I have never felt a need to do that, nor have I ever developed any symptoms of imbalance on a previously balanced wheel (unless a weight was thrown.)

The inequity of weight on the new tire would be in the tire's carcass, not in its tread rubber. Theoretically the peripheral tread will wear uniformly around the tire circumference and remain in balance. The exception would be if the wheel was out of balance and bouncing down the road, then the rubber may be worn away unequally and exacerbate the imbalance over time.

Most lead is radiologically stable and does not decay. Now if you needed more weight and were using uranium (238U) then the uranium will decay in a series of steps culminating in lead (206Pb), a decay rate with a half-life of roughly 245,500 years at which time you should rebalance your tire.

Only Gen 1 owners need to worry about this since they are the only ones that will never have the common sense to upgrade their scoot.

238U half life is a LOT longer than 245,500 years - more like 4.47 billion years! Won't need to rebalance for a very long time. 234U (natural abundance 0.005%) has the 245,500 year half life.

 

[yamafitter]

Aren't lead weighted tires supposed to be re-balanced at their half life?

Most lead is radiologically stable and does not decay. Now if you needed more weight and were using uranium (238U) then the uranium will decay in a series of steps culminating in lead (206Pb), a decay rate with a half-life of roughly 245,500 4.46 x 109 years at which time you should rebalance your tire.

Only Gen 1 owners need to worry about this since they are the only ones that will never have the common sense to upgrade their scoot.

238U half life is a LOT longer than 245,500 years - more like 4.47 billion years! Won't need to rebalance for a very long time. 234U (natural abundance 0.005%) has the 245,500 year half life.

Well Ross it is not going to matter because as soon as the NSA finds out you are using uranium they are going to arrange to run a depleted plutonium tipped drone up your anus within 24 hours.

 

[RossKean]

You mean depleted Uranium - aka 238U with the good stuff (235U) removed?

I don't know how fussy they are with either depleted Uranium or even natural (non-enriched) uranium. (~0.7% 235U). We certainly use (small) quantities purchased as standard solutions in the analytical chemistry lab where I work. Probably no more than a gram on-site but no regulatory process to buy; although you might pique someone's interest if you tried to purchase large amounts.

 

[RaYzerman19]

Aren't lead weighted tires supposed to be re-balanced at their half life?

Most lead is radiologically stable and does not decay. Now if you needed more weight and were using uranium (238U) then the uranium will decay in a series of steps culminating in lead (206Pb), a decay rate with a half-life of roughly 245,500 4.46 x 109 years at which time you should rebalance your tire.

Only Gen 1 owners need to worry about this since they are the only ones that will never have the common sense to upgrade their scoot.

238U half life is a LOT longer than 245,500 years - more like 4.47 billion years! Won't need to rebalance for a very long time. 234U (natural abundance 0.005%) has the 245,500 year half life.

Well Ross it is not going to matter because as soon as the NSA finds out you are using uranium they are going to arrange to run a depleted plutonium tipped drone up your anus within 24 hours.

True story.... went across the bridge in Niagara with two buddies in my truck. Border guards first words, "Anybody had a nuclear stress test recently"...... never heard that question before. One buddy fesses up he had one a few days ago. We had to all go inside and get scanned with a handheld (multiple times), and the truck was driven through a large scanning device while we were detained. Turns out the US boys have the large scanners at the entrance to the lane..... the amount of isotope in a nuke stress test is miniscule (head of pin size), yet it picked it up as we drove in. No scanners on the Canadian side, I guess we trust that nobody's building nuke weapons. Anyway, wait a week or two after you've had a nuke stress test before crossing the border.......

 

[dcarver]

All I got to say is I got yer dyna beads hanging!

 

[mcatrophy]

...25kts for the G450 and only 10kts for the CE680. That's the limitation anyway, they don't actually say in the manual it won't start, just that you shouldn't. It'd be interesting to know what the real number is.

The risk is that the engine will start to spool up, then be unable to pull in enough air, the compressor will stall and the engine will overspeed (surge). Generally a VERY BAD THING.
A bit off topic, but I'm bored.

 

[Chuck35]

FWIW I balance my car tires (the ones on the car) when I rotate them. Often at their 1st R&B after install the amount of weight is reduced by 1/2.

 

[ionbeam]

..."Anybody had a nuclear stress test recently"...... never heard that question before. One buddy fesses up he had one a few days ago...the amount of isotope in a nuke stress test is miniscule (head of pin size), yet it picked it up as we drove in...

Another micro hijack. One of the unfortunate byproducts of an ion implanter (used to make advanced integrated circuits) is radiation. Everyone in the test department wears a radiation monitoring device.

One day I was testing a high voltage power supply for radiation leakage. It pinned the needle on the Geiger counter, I clicked the next range, still pinned. I shut off the supply and the needle was still pinned

I clicked the next rang and the needle was still pinned. This was serious but curious because it wasn't coming from the power supply. I was able to use the meter like a directional finder to lead me to the source. It immediately led me to the twenty or so ion beam machines in test. I was able to narrow it down to one machine but it wasn't connected to power

Then Walter stepped out and the meter went nuts. That's when he explained that earlier in the day he had had a thallium stress test. I asked him to close himself up in the lead lined compartment in the back of the machine while I go to personnel and explain why 60 of us were going to fail our radiation monitoring tests. We might as well have worked at Fukushima that day. I asked him if he could check with his doctor and see if he was accidentally given (way) too much thallium but never got an answer back from Walter.

 

[wheatonFJR]

whoa.

 

[mcatrophy]

... but never got an answer back from Walter.

Is Walter no more?

 

[2fjr]

Back to beads for a second.......

This debate has been rehashed for years with pretty much the same old stuff being said. Funny that the Dynabead website only has a cartoon and a series of anecdotes to support the claimed performance. If they really wanted to show folks how it works, they could easily build a clear tire mockup and shoot it in slow mo to prove how it works. Seems to me that would be much more powerful as a demo than a stupid pop bottle chucked up to a drill.