I would like to bring the topic of chain weight and it's effects on performance up for disscussion. Sorry if this is a bit long.
I received a couple of loops of full chisel carleton chain as an early Christmas present from my dad, right away I noticed that it was lighter than the Stihl RS chain I have been. The tie staps were visually thinner on the Carleton chain, so I weighed the two chains.
Note both Stihl and Carelton chains were sharpend for ripping so they would have about an equal ammount of metal removed.
Stihl 3/8 full chisle 20" = 380 grams or 13.5 oz
Carelton 3/8 full chisle 20" = 335 grams or 11.9 oz
Wow 10% difference
On a 32" chain it's nearly 100 grams or about 3.5 oz difference, though I was compairing full comp to semi skip for the 32".
I tried to look at it from a mathmatical formula to determine how much energy is used in accelerating the extra weight around the tip of the bar and the drive sprocket, but the calculations got rather convaluted and would require other data like coefficient of friction (chain to bar) to get a quantative awnser. No matter how I approched the formula the mass of the chain always formed a direct relationship to the forces required or generated.
So my guess would be: That what ever the losses were asotiated with a given chain would be increased proportionatly with increased chain weight.
ie. 10% increased weight would increase related power losses by 10%, also 10% increase of forces exeted on centripitally related wear point of the bar and crank bearing.
Other interesting numbers I found while trying to support this hypothisis with calculatons. (based on 13500 rpm 8 tooth sprocket 3/8 chain)
Each drive link passing arround the bar places about 20 lb of outwar force at the tip, a 30 lb at the sprocket.
about 1400 teeth pass over the tip of the bar every second
about 15 lb of chain is slung around the tip of the bar every second. That is 85000 teeth weighing 900 lb a minute or 5.1 million teeth weighing about 25 tons an hour.
Anyone have Ideas on the real world impact of chain weight, or approches that could be used to calculate the therotical values.
This is likely theroretical and not a practical point, but it should be an interesting discussion.