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testing out Dynabeads...

schristo@mac.com

[email protected]

Well Known Member
No problems, but I like to tinker... This past weekend I installed new HID landing lights in my ductworks leading edge units, put together a wing jack, and loaded up my tubes with an ounce of Dynabeads in each tire. The weather went to **** but this week is looking spectacular and I am planning to take advantage of it :)

Dynabeads are very small ceramic beads that are inserted into your tire or tube and will dynamically balance the wheel assembly while it is rotating. I ran into these on a motorcycle forum some time ago and have had it on a fuzzy list to give a try with the airplane...

Here is a 2 ounce package of the beads.
img1015gg.jpg


You remove the valve stem and slowly coerce the beads into the tube, vibration on the stem helps the beads to make entry... it is slow.

img1017jl.jpg


They recommend that you replace the valve stems with filtered ones.

img1019g.jpg


Anyone using these?

I will report back after flying with them.


Here is a video demonstration.
http://youtu.be/eq263AYgyYg
 
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Dynabeads testing

I don't have any noticeable shimmy or wobble but I never balanced my tires... I really like the idea for a motorcycle tire, especially if you change them yourself and don't have access to a balancer. The dynamic balance is quite appealing in concept since you effectively rebalance every time the wheel turns.
 
This has been discussed before and it's good to see someone actually testing it.

My personal theory is that you will see marked improvement on take-off and it will shimmy on landing and then smooth out.

On take-off (and on your motorcycle) the wheel slowly accelerates -- giving the beads time to take their respective positions around the inside of the tire. In the airplane on landing the wheel goes from stationary to touch-down speed instantly and all of those beads will be hanging out on the bottom of the tire.
 
followup observations

Weather around Seattle was especially spectacular with more of the same for the weekend! I made two flights with some lengthy taxiing and a runway length high speed roll out with the tail up to test out the Dynabeads.

Short impression... Nice!

During low speed taxi I could not notice any changes with the Dynabeads. As the speed passes 12-15 I have a vague sense that there is some smoothing in the ride, not a lot, but I suspect that the tire is rotating fast enough that the beads actually find a stabilized position to dynamically balance the tire in this range. At a high speed taxi I had a small wheel vibration at right around 21-22, with the beads it is reduced significantly.

Where the beads seem to shine is at higher speed. The take off roll out was dramatically SMOOTH, and I mean smooooooooth. I have always noticed some wheel transition at take off as the gear and tire unloads but with the Dynabeads there was none... it feels a bit eerie.

I thought that there might be some oscillation at moment of touchdown but if there is any you don't feel it... with the wheels rolling it is just smooth ;)

I am going to video the gear tomorrow and compare it to some similar footage before the beads.
 
Thanks for the update.

I have a shimmy at fast taxi, due to a tire issue I think. IT's better after I balanced it, but I can still get my right gear shaking if I taxi fast. I may try the beads, before I go with gearleg stiffeners
 
Stephen,
Are there any concerns in the motorcycle community that these beads may harm the tube or the tubeless tire, over time? I watched the video and there is a lot of movement of the beads every you stop and start. Is there a chance of the beads breaking down?
 
Thanks for the report Stephen. I had slightly out of balance main wheels on my Cub when I owned her. I could have done with this product then. I will be making a note of this thread for future reference. I will be installing the slightly larger tyres (tires) on my RV-4 as done by Steve Sampson and Dynabeads will be sourced and installed by the pour in method as described on their website. I was an avid bike rider in the UK about ten or fifteen years ago. I suspect I would have used Dynabeads if they were available then in the UK.

However, that was a really good report and many thanks.

Tony
 
Works great in my truck

I have 19.5" commercial tires on my pickup. I have heard they are impossible to keep balanced. Went with the dynabeads about 3 years ago (40,000 miles), and love them. Was told by the tire shop to use them on an unbalanced tire.

The only problem I had was if I let the pressure get too low, some beads got between the rim and tire and caused a leak. Had to have the tire removed, seat cleaned and reinstalled. Would not be an issue with a tube.

Where did you find the filtered valve stem? I don't have those, and need to add a little air after checking the pressure to clean out the valve stem.

By the way, in keeping this RV related, just ordered the finishing kit last week!!!!
 
the dynabeads website has the filtered valves for $1.30 and they also have the cool tool to remove them for a little of $3.00

-david
 
Hi Guys

I am really interested by this thread as I get really bad wheel shake after take off in my current aircraft not an RV (my RV7 is almost ready for paint) , one question though, have any of you thought about what you would do if you got a puncture while away on a trip?

Would you replace the tube and try to add extra beads or just put up with one tire being out of balance ?

Cheers
Eddie
 
Its actually the nose wheel that is causing the shake.....sorry should have mentioned that, transitioning to tail wheel soon.

Cheers
Eddie
 
Stephen,

How much did you put in each tire? I'm sure that the amount will vary depending on how out of balance a tire is, but just wondering what would be a reasonable amount to purchase?

Greg
 
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