YUJIGOLF Singapore

• 07月29日・・・We started delivery service
• 07月01日・・・iron head arrived
• 06月22日・・・Golf Science Swing Weight 1
• 06月21日・・・Golf Science Swing Weight 2
• 06月13日・・・Golf Science - Gravity depth

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Car Parking Space

Dear Customers,
There are more parking space along Mohammed Sultan Road.
Please refer to the map shown below.

Please Take Note:Day & night car park coupon 50 cents for half an hour.

Time : 8.30 a.m. to 10 p.m.  daily.

We started express delivery service cooperated with Yamato Transport.
Please use this safe and reliable services.

Fee is depend on size : $6 to $25

Dear customers , iron head has arrived.

Very sorry to have kept you waiting so long time.

Please visit our shop.

We will talk about swing weight or swing balance or so-called a balance this time. (In the following, it unites by the expression “Balance”. )

Balance is

“Moment” in point circumference of 14 inches from grip end

in physics.

It has been believed for a long time that the value of the balance shows the heaviness of the weight felt during swing . However, many people knows that it is a complete mistake. It comes to a common sense now. Then where is the mistake?

1)No one grasps 14 inches from the grip end.

2)The golf swing doesn’t rotate  around 14 inches from the grip end.

In the old times all the shaft made of steel  and all the grips are about same weight(around 55g), so this wrong concept was not that troublesome at that time . But now, you can choose light shaft to heavy shaft and grip size also same.

Now you cannot say “D2 fells heavier than C8″.

For simple example, if you change grip from light one to heavy one, the club become heavier and you feel heavier also, but balance become lighter.

As mentioned above, When neither the shaft weight nor the grip weight are the same, balance cannot use for the comparison at all.

You had better think about the total club weight rather than swing weight.

You can find a swing weight scale in most golf shop. But you can also measure it yourself by using weight scale and measuring tape .By doing this , you can try &  calculate it by  trying this method.

Before this you should  know the calculation formula :

1inch=2.54cm  1ounce=28.35g

Take  an example of  a  driver

length 45.75inch ,  weight 307.8g (= 10.86ounce)

balance point from grip end is 83.5cm

As mentioned before at moment ,

Moment is

(distance from action point and center of rotation ) x (force)

action point : 83.5cm = 32.87inch

center of rotation : 14inch from grip end

32.87-14 = 18.87 inch

then multiple by force ( = club weight)

18.87×10.86 = 204.9 inch.ounce

Please see the table
C8 = 210 inch.ounce

So 204.9 is very near to C5.

And mesure it by swing weight scale, then get the same result.

That is ok.

In addition

The balance is calculate from the value of the moment (inch ounce) when expressing it in

A0 → 0 , B0 → 10 , C0 → 20 ,  D0 → 30

⇒   balance = (moment -161)x4/7

= 25.08         so C5.08

It is said  direction of a golf ball is good when the gravity depth is deep.
Let’s think about functions of gravity depth .
In these case of hitting position is d away from the sweet spot.

Graph  shown above are both cases of gravity depth

1. shallow gravity depth : G1
2. deep gravity depth : G2

The force  that  ball push the head : f

Deepness of  both gravity depth : x1,x2

θ1,θ2 are expressed in formula ①,② by using trigonometric .

f (red) is divided by  f1(green) and  green  dash line force.

The angle between  f and f1  is θ1.

f1 –> formula③　  and   f2 –> formula④

It is easier for you to calculate this method  by using YUJI GOLF TECH BASE.

Try to calculate this case  x1= 5mm , x2 = 35mm , d = 10mm

→　f1= f x 0.894    f2 = f x 0.275

f2 is much smaller than f1

It means = ”deeper gravity depth”

⇔ “the force to turn the head is small”

⇔ “better direction”

This calculation only apply to miss shot ball , if  d=0 , makes no difference for G1 and G2.

Hi everyone! Have you consider about the lie angle when you choose iron clubs.?  Do you understand how much influenced to the result if the lie angle is not suitable for you?

The angle deviation of the direction can be calculated by mathematics though it is a bit troublesome at times .

First,you express the face of the iron by the equation.

Then you calculate the angle of the face normal and the direction of the target for different loft and lie.

As you know, when you hit the ball with upright lie then ball goes left, and when you hit ball with flat lie then ball goes right.

Is this influence the same when it has more loft and less loft?

Try to  image  3D view in your mind.

If the loft angle is 0 degrees, it doesn’t influence to direction with any lie angle.

The influence of the lie angle increases by having more loft.

Let’s calculate it by our YUJI GOLF ” TECH BASE “.

An example) deviation of the lie angle is 5 degrees

Loft 15 deg   —->  1.34deg

Loft 25 deg   —->  2.33deg

Loft 35 deg   —->  3.49deg

Loft 45 deg   —->  4.98deg

Loft 55 deg   —->  7.10deg

Consultation fee : S$50
Consultation time : 30 to 45 minutes

Consultation details:
Minimum 2 - 3 pieces of golf clubs.
Current using driver, iron # 5 or # 7 and one more club ( wood or putter).

Consultation description:
Full golf club specs check up.
Full golf swing analyze.
Analyzing ball trajectories.

For booking appointment kindly do contact us in advance .

Golf science - Side Spin

What do you know about side spin .”One that causes ball to slice or hook. “It might be understood that it is two dimensions of rolling in your image .

In Figure 1,
The traveling direction ..Z.. , and the rotation around the X axis is backspin and rotation around Y axis is the side spin. This image seems to be correct but actually it is not.
Let’s think a little bit more in a scientific manner by three dimensions or 3D .
When there is no side spin as shown in Figure 2, the spin axis horizontally becomes only a backspin and it becomes a straight ball. When the side spin enters it, the spin axis inclines and it becomes the slice and a hook as shown in Figure 2.
The backspin and the side spin are calculated by resolving the number of total spins from the inclination of the spin axis to X axis element, Y axis element, and Z axis element. For instance, when inclinations of the axis are 45 degrees (z axis element as 0), the backspin becomes equal and becomes big curved with the side spin. Moreover, if this becoming almost 90 degrees when hitting ball onto the toe side it cause ball to shank ,it can be quite embarrassing at times.
What is Z axis element here?
These spins are often seen by throwing darts or shooting bullets from guns or releasing an arrow.
Posture can be stabilized by this in the bullet etc. but in golf though it is not useful.
This is one of the gyroscopic precessions.

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