Thoughts on Stabilisation.

[Jerry Tee]

I have been thinking a lot recently about long rods. and I have developed a few theories. When I started shooting many years ago the basic use of a long rod was to stabilise the aim. The function of vibration absorbption was left to a pair of twins with TFC's forward facing at the point where the limb was attached the the riser.
Modern compounds seem to have seem to have imposed another role on the long rod, that of vibration or hand shock absorbption. The lenght of the rod would seem to have two functions. Firstly the frequency of the vibration to be absorbed the longer and more flexiable the lower frequency. An end weight would have the effect of softening to rod in a similar way to the point weight of an arrow. The shorter twins appear to be able to absorbe higher frequency and to counter balence the long rod. Allowing it to be longer.
so my question is this.
In parallel limb compound bows do we really need a long shock killing long rod or is that so much extra windage. Would that bow be better served by optimising a stab to the aiming side? and the vibration left to a pair of twins?
I ask this because I noted that Paul used a short carbon rod on a windy day with good results and posted his experience.

[not dead yet]

i know someone who shoots target with a 10 inch longrod on a bowtech. and it works very well

[geoffretired]

Interesting! My first long rod was home made, (nothing 's changed)
It was made from tubing that had once been my baby daughter's relaxer seat frame. It was a success at the time. It slowed the rapid movements during the aim and gave more time to release.
It was so good that I decided to make another from proper tubing and I put more effort into getting it "right".
It was a disaster as the tubing was too flexible; so I went back to the first one for a while.
Then the hydraulic ones came into fashion. I made two. The first was short and fat and rigid. It absorbed vibrations as liquids do and gave a fairly steady aim, but being short it was not so good at the aim as a longer one and it was very heavy to give the right balance. The second was longer and worked well in both respects.
From my own experiences; not drawing on the experiments of others that would probably give more insight into this subject, these are my thoughts;
Too heavy and I can't hold the mass at arm's length.
Too light and it doesn't seem to work.
Too short and the stability of the aim suffers.
Too long and there is little control as the tubing flexes so easily during the power stroke.
Some combinations/materials produce more vibration than the naked bow.
My conclusions are these;
There is a range of lengths that will allow me to keep the system rigid, light enough to hold up, long enough to steady the aim,and constructed in such a way that it cuts out most of the vibrations. For me and my bow that range is around 24-30 inches with the weight adjusted to give the balance just in front of the throat.
Archers with more aggressive bows than mine, because of type or poundage, may need more mass to help control their bows. Some of this extra mass may have to be on the v-bar system as it would upset the balance to have it all in front.
I tried TFC's once. The flexible coupling meant that the bow would torque yet leave the short rod unmoved. All they did was add weight and did nothing for control of torque, despite their name. Many archers tightened them to the point where they were almost rigid in order to get some better results!!
I view vibration damping as one task and best done by special materials like the rubbery things.
Stabilsation is another task, best done by long rigid rods of some sort.
Shock absorbtion is as much to do with bow design as anything else but if your bow produces a shock that is too great, mass added somewhere will reduce it.
There are products that include parts that do a good job at reducing shock and vibration while adding stability. I'm lucky, as my long rod can do all three.

Good post Geoff

I agree with pretty well everything you have said on this subject. I thought I might add a couple of my own thoughts borne out of recent experience.

Of all the stabilisers I have tried the one which I found gives true shock/vibration absorbtion is the Doiniker Carbon Elite A2 - the one with the so-called suppression chamber on the bow end and the Doinker A Bomb rubber module and weight. I have tried the so-called TFCs and like Geoff have found that they are really a waste of time and money. I don't know how the Doinker suppression chamber works but I had a spare one at home that I put on my recurve recently and what a change it made, The bow now fires with a cris[p hum and no handshock at all. It really feels good in the hand so there must be something in the chamber that is doing its job because the recurve has never felt better.

I too have problems with overlong stabilisers. Both my compound and recurve stabs are around 28" and in still conditions they are really comfortable to use. However of late we have had really strong gusting winds at our range and both my stabilisers have proved to be extremely difficult to control. My current thinking is that for these conditions I need to go with a smaller stabiliser.

I'm thinking that I will use the spare Doinker suppression chamber and attach a short length of carbon graphite fishing rod to this - about 10 " - , with slots cut into it to allow free air flow, and on the end fit a small Doinker rubbber and make up an aerodynamically shaped cross sectioned, round, flat steel disc on the end as a weight. This should give me a length of around 18" and a weight of around maybe 1.5 lbs - heavy , but at 18" I think this will be manageable. It will look somewhat like this:



I hope to have this done up soon after Christmas so I will report on how it woprks (or doesn't) on both of my bows early in the New Year.

[pwiles1968]

Originally Posted by timujin

I'm thinking that I will use the spare Doinker suppression chamber and attach a short length of carbon graphite fishing rod to this - about 10 " - , with slots cut into it to allow free air flow,

Timujin - I would be careful about adding slots to aid air flow, I am not an aerodynamics expert but I think thease may actually have a detrimental effect and create turbulence and increasing drag, as far as i am aware a teardrop cross section shape is the most aerodynamic you can get but as you do not know exactly which direction the wind will be coming from it would be useless, a cylinder is actually fairly aerodynamic if you wanted to improve the cylinder you could add dimples (like golf ball) but my feeling is putting slots in would not be as good as a solid section.

I am reading these posts with a great deal of interest, i am currently at the stage of changing my stab setup, I have a 33" Beiter with a single solid ali side bar for balance, the beiter is terrible in the wind and I was thinking of going for a short 20-24" carbon rod with end weights & small rubber doinker. I know Merlin can make their long rods pretty much any length you like and will probably have a chat with the guys on the 30th after the frost bite.

[pyroarch57]

[quote=pwiles1968;92349]as far as i am aware a teardrop cross section shape is the most aerodynamic you can get but as you do not know exactly which direction the wind will be coming from it would be useless.

Not if you make it like i mentioned to Geoffretired. Have it fixed with a ballrace at the base so it can easily rotate, this way it will always be facing into the oncoming wind, and being a perfectly symmetrical airfoil section will have no upward or downward push.

[Jerry Tee]

One question Paul , why the Doinker on the end of the long rod? If you stick it right out the front it is extra side area for the wind to blow against. Would the doinker do the same job mounted on the back of the bow or on the ends of a pair of short twins, or on a single back rod offset to take into account the weight of the sight.That would allow you to pick a long rod that helped you aim best. What do you think?

[Jerry Tee]

[quote=pyroarch57;92359]

Originally Posted by pwiles1968

as far as i am aware a teardrop cross section shape is the most aerodynamic you can get but as you do not know exactly which direction the wind will be coming from it would be useless.

Not if you make it like i mentioned to Geoffretired. Have it fixed with a ballrace at the base so it can easily rotate, this way it will always be facing into the oncoming wind, and being a perfectly symmetrical airfoil section will have no upward or downward push.

Unfortuntately it will rotate in the wind I use to have a kite that worked on the same principle with freely spining simetrical aerofoil shapes

[geoffretired]

What will that rotation do to the performance?

[pwiles1968]

Originally Posted by Jerry Tee

One question Paul , why the Doinker on the end of the long rod? If you stick it right out the front it is extra side area for the wind to blow against. Would the doinker do the same job mounted on the back of the bow or on the ends of a pair of short twins, or on a single back rod offset to take into account the weight of the sight.That would allow you to pick a long rod that helped you aim best. What do you think?

That is quite a good idea was thinking of the doinker as a weight and the Merlin version is fairly slim, but you are correct about it catching wind, the Tribute is so neutral i probably don't need a doinker at all, but one of the side rod would be fine. I will have to have a shoot and see what the bow feels like with and without.