This report will outline how this study came about, how it was conducted and an analysis of the findings from the four slopes; the two side slopes, the uphill slope and the downhill slope.
ReasonsMy reasoning for making this study is: I knew the effect that the various slopes had on the both the ball flight and trajectory; I also knew the ways in which I needed to adjust my setup to get the best possible results from them. However, I wanted to know, if each of the slopes had the same degree of tilt, would the difference in the flight or the trajectory change by the same amount for each slope. ProcedureTo make this study it was vital that the four slopes were the same. The only way to guarantee this was by having one slope and using it in all four directions, and I chose to use 7° tilt (7.2° to be exact) as I felt that this was a slope of medium severity. There was however one exception, the downhill slope. For this series of shots this one slope was used to stand on to play the shots but the ball was not placed on it. The reason being that because the slope was solid, TrackMan could see the flight of the ball without any problems but not the impact and therefore could not give most or any of the club data. I solved this problem by building a second slope, to the same specifications (0.25° more) out of PVC plastic, which allowed TrackMan to see through the slope and for it to give all club and ball data. For all the shots, I used new out of the box Callaway Chrome Soft balls and the same three clubs: an 8iron, a 6iron and a 4iron from the same set and were checked to have standard lie and loft. 
MethodTo begin I hit ten balls from the flat with the 8iron, 6iron, and 4iron, and these would serve to be my baseline throughout the study. I then proceeded to hit thirty shots from each slope, ten with each club, the only exception was the downhill slope. When hitting from the PVC slope I needed to hit more than the thirty shots as all the data didn’t arrive every time, whether it was because the slope bounced with the impact of the shot or whether it was because TrackMan didn’t believe the numbers and so it didn’t report them. I made a conscious effort to swing comfortably and in the same way each time. I felt that this was important to the study as I wanted to see what the true effect of the slopes are and by swinging at my normal speed I felt that it would allow for my hands and body to make corrections and compensations, making the data inconsistent and void. AnalysisFor the analysis, I have removed the bad shots and I will discuss them separately. I will also make two groups for the slopes, one with the two Side slopes and one with the uphill and downhill slopes. I will do this so that a comparison can be made between the slopes that relate to each other. NormalizationThroughout this study normalization has been used, and when it has been used it is clearly marked. The settings are as follows: 0 meters of altitude and 25°C. 
Side slopesThe key numbers here are: Launch Direction, Spin Axis & Side. FlatI feel that it is important to begin with the numbers from the flat, as this is the baseline for all the other numbers to come. When we look at the averages of the three clubs, the balls are launching less than half a degree left of the Target Line, have a very small amount of Spin Axis and are finishing less than two and half meters from the Target Line. This is however only part of the story; we can see from the photo to the right there were shots that landed both left and right of the Target Line. When we look at the individual shots there was only three out of twentysix shots (11.54%) that launched more than 1.5° from the Target Line; there was only three shots (11.54%) that had more than 3.5° of Spin Axis; and only four shots (15.38%) that finished more than 7.5 meters from the Target Line. 
Side Slope – Ball Below Feet
If we start by looking at the beginning of the balls journey, the Launch Direction, we see that the balls are launching on average between 1.6°2.0° to the right of the Target Line, which is more than 88% of the shots from the flat. In fact, only 21% of the shots selected started less than 1° to the right of the Target and more than half of the shots started more than 1.5° to the right of the Target Line.
Flat Launch Direction 
Ball Below Feet Launch Direction 
Difference  
4 Iron  0.4°  1.6°  2.0° More Right 
6 Iron  0.1°  2.0°  2.1° More Right 
8 Iron  0.1°  1.7°  1.8° More Right 
Then when we look at the second part of the flight we can see that the averages of all three clubs have a positive Spin Axis: 4.6°, 1.9° and 2.2°. Nearly 74% of these shots had positive Spin Axis whereas there was less than 46% of the shots from the flat that had positive Spin Axis and when we look at the Faceto Path, every shot played from the slope had a positive Faceto Path so we could say that the shots that didn’t have the positive Spin Axis were the result of a noncentered strike and in these cases, they were struck slightly on the toe.
Flat Spin Axis 
Ball Below Feet Spin Axis 
Difference  
4 Iron  2.1°  4.6°  6.7° More Positive 
6 Iron  0.7°  1.9°  2.6° More Positive 
8 Iron  0.7°  2.2°  1.5° More Positive 
The third and final part to the flight is to see how far did the shots land from the Target Line. The average Side with the NonNormalized data from the three clubs was between 9.9 and 15 meters to the right of the Target Line, the smallest amount was + 3.4 meters and the most was +25.4 meters. However, when we Normalize the data we see that the Side averages drop to 6.8, 7.3 and 11.1 meters to the right, with the furthest shot to the right finishing 17 meters right of the Target Line.
Flat Side(m) NonNormalized 
Ball Below Feet Side(m) NonNormalized 
Difference Side(m) NonNormalized 
Flat Side(m) Normalized 
Ball Below Feet Side(m) Normalized 
Difference Side(m) Normalized 

4 Iron  2.3 L  15.0 R  17.3 More Right 
4.6 L  11.1 R  15.7 More Right 
6 Iron  1.9 R  12.8 R  10.9 More Right 
1.3 L  7.3 R  6.0 More Right 
8 Iron  1.3 R  9.9 R  8.6 More Right 
0.6 R  6.8 R  6.2 More Right 
Side Slope – Ball above feet
With the second slope in this group we will also start by looking at the beginning of the flight, Launch Direction, and working forward. We can see that with all three clubs the balls are launching to the left of the Target Line, their averages are: 1.1°, 2.1° and 2.6°. What is interesting is that 100% of the shots played from this slope had a negative Launch Angle, whereas from the flat there was less than 54% that had a negative Launch Angle. With the 4iron from the flat there was only one ball (14.29%) that launched more than 2°, whereas more than 83% of the shots from the slope did. With the 6Iron from the flat none of the shots launched 2°, whereas more than 57% of the shots from the slope did. With the 8iron from the flat only one ball (11.11%) launched more than 1°, whereas more than 57% of the shots from the slope did.
Flat Launch Direction 
Ball Above Feet Launch Direction 
Difference  
4 Iron  0.4°  2.6°  2.2° More Left 
6 Iron  0.1°  2.1°  2.0° More Left 
8 Iron  0.1°  1.1°  1.0° More Left 
With the second part of the flight, the Spin Axis, we can see that all the averages of the three clubs have a negative Spin Axis: 6.3°, 2.2° and 5.4°. The amount of shots with negative Spin Axis increased from nearly 58% from the flat compared to 85% from the slope, and only one of the three shots that had positive Spin Axis was due to a positive Faceto Path ratio, the other two were due to an offcenter contact, and in these cases towards the heel. Where there is, a big change is the amount of Spin Axis that the shots from the slope had, more than 76% (13/17) had more than 5° of tilt, compared to less than 7% (1/15) from the flat.
Flat Spin Axis 
Ball Above Feet Spin Axis 
Difference  
4 Iron  2.1°  6.3°  4.2° More Left 
6 Iron  0.7°  2.2°  1.5° More Left 
8 Iron  0.7°  5.4°  6.1° More Left 
With the final part to the flight, the Side, all the shots finished to the left of the Target Line: 9.1 meters, 10.1 meters and 14.3 meters for the NonNormalized data. The smallest amount that any of these shots finished left was 2.6 meters and the largest was 20.3 meters. When Normalized, the numbers changed slightly to: 8.8 meters left, 8.6 meters left and 16.8 meters left. There were two shots that finished to the right of the Target Line, the most being 1.4 meters right; these are the two shots with heel contacts mentioned before.
Flat Side(m) NonNormalized 
Ball Above Feet Side(m) NonNormalized 
Difference Side(m) NonNormalized 
Flat Side(m) Normalized 
Ball Above Feet Side(m) Normalized 
Difference Side(m) Normalized 

4 Iron  2.3 L  14.3 L  12.0 More Left 
4.6 L  16.8 L  12.2 More Left 
6 Iron  1.9 R  10.1 L  12.0 More Left 
1.3 L  8.6 L  7.3 More Left 
8 Iron  1.3 R  9.1 L  10.4 More Left 
0.6 R  8.8 L  9.4 More Left 
Comparison
When we look at these two slopes Side by Side we can see that they are producing the same results, the only real difference being that one produces positive numbers and the other produces negative numbers, but have the numbers moved a comparable amount?
In the Launch Direction, the slope with the ball below the feet the 4iron launched 2° more to the right than the flat and from the slope with the ball above the feet launched 2.2° more to the left than the flat. The 6iron with the ball below the feet launched 2.1° more to the right and with the ball above the feet launched 2° more to the left than from the flat. With the 8iron the ball launched 1.4° more to the right when the ball was below the feet and 1° more to the left when the ball was above the feet when compared to the flat. A maximum of 0.4° of difference in change, incredibly consistent, will the same be true for the other key numbers?
Ball Below Feet Launch Direction 
Difference  Flat Launch Direction 
Difference  Ball Above Feet Launch Direction 

4 Iron  1.6°  2.0°  0.4°  2.2°  2.6° 
6 Iron  2.0°  2.1°  0.1°  2.0°  2.1° 
8 Iron  1.3°  1.4°  0.1°  1.0°  1.1° 
For the Spin Axis, the numbers are quite similar but due to the horizontal gear effect there are some discrepancies. In the 4iron, there was a +6.7° change with the ball below the feet and a change of 4.2° with the ball above the feet, so a 2.5° difference of variance. For the 6iron with the ball below the feet there was a +2.6° change and with the ball above the feet there was a 1.5° change, so only a 1.1° of variance.
For the 8iron, with the ball below the feet there was a +1.5° change whereas there was a 6.1° of change with the ball above the feet, so a rather large 4.6° of variance. If we looked at each of the shots individually, none of the shots had a very similar Spin Axis, all in the right area but all different. This is of course due to the slightly different points of contact that each shot had, some center, some slightly towards the toe and some slightly towards the heel. With a contact, just 1 centimeter from the center of the face could affect the Spin Axis by up to 6°, so the only way for these numbers to be very similar would to have the same point of contact for each of the shots.
Ball Below Feet Spin Axis 
Difference  Flat Spin Axis 
Difference  Ball Above Feet Spin Axis 

4 Iron  4.6  6.7  2.1  4.2  6.3 
6 Iron  1.9  2.6  0.7  1.5  2.2 
8 Iron  2.2  1.5  0.7  6.1  5.4 
When we look at Side we have two groups of numbers, Normalized and the NonNormalized. If we start by looking at NonNormalized numbers we can see that the averages of balls played from the slope with the ball below the feet landed: 8.6, 10.9 and 17.3 meters further to the right than the flat and the averages with the slope with the ball above the feet, the balls finished: 12, 12 and 10.4 meters further to the left than from the flat.
Even though the amount the shots landed from the Target Line varied, what is interesting is that the average change from both slopes is very similar, with the ball below the feet the mean of the change is 12.3 meters and with the ball above the feet the mean of the change is 11.5 meters, so only a difference of 0.8 meters which is quite consistent. When we look at the Normalized numbers, the same is true. The mean of the increase in change with the ball below the feet is 10.2 meters and with the ball above the feet the mean of the increase in change is 9.6 meters, a 0.6 of difference.
Ball Below Feet Side(m) NonNormalized 
Difference  Flat Side(m) NonNormalized 
Difference  Ball Above Feet Side(m) NonNormalized 

4 Iron  15.0 R  17.3 More Right 
2.3 L  12.0 More Left 
14.3 L 
6 Iron  12.8 R  10.9 More Right 
1.9 R  12.0 More Left 
10.1 L 
8 Iron  9.9 R  8.6 More Right 
1.3 R  10.4 More Left 
9.1 L 
Ball Below Feet Side(m) Normalized 
Difference  Flat Side(m) Normalized 
Difference  Ball Above Feet Side(m) Normalized 

4 Iron  11.1 R  6.5 More Right 
4.6 L  21.4 More Left 
16.8 L 
6 Iron  7.3 R  8.6 More Right 
1.3 L  7.3 More Left 
8.6 L 
8 Iron  6.8 R  6.2 More Right 
0.6 R  9.4 More Left 
8.8 L 
ReasonsThe reason why the slopes have had these effects on the shots is quite simple, the slopes have required the player to stand and swing in a certain way to make solid contact with the ball. This steepening of the shaft will change the way that the club sits on the ground and even though the leading edge is 90° to the Target Line the Face Angle will point to the right, this will cause the change in Launch Direction. Another effect of having the club more upright it will also steepen the Swing Plane which will cause the Path to be closer to the Swing Direction, this will be minimal but will never the less help to produce more positive Spin Axis. With the ball above the feet the player will have less forward lean of the upper body to reach the ball, and as the player is standing more upright the shaft angle at address and impact will be flatter. This flattening of the shaft will change the way the club sits and will cause the Face Angle to point more to the left even if the leading edge is 90° to the Target Line, this will cause the balls to launch more to the left. The second effect of this posture and flattening of the shaft will be to also flatten the Swing Plane, this will push the Club Path further from the Swing Direction this will be slight but will never the less cause more negative Spin Axis. 
Straight ShotWe have seen that the mean change in the amount of Side was between 9.6 and 10.2 meters, so it would be easy to aim this amount right or left of the Target and simply let the ball curve towards the Target, however, what if we wanted to play a straighter shot or the situation wouldn’t allow for the curvature? Well we can see that the average Face Angles on the both slopes are, for the ball below the feet: 1.9°, 2.4° and 2.5°, and for the ball above the feet: 3.0°, 2.4° and 1.3°. The mean number for the both are: 2.3° and 2.2° respectively. So therefore, all we would need to do is to open or close the face at address about 2° and we would be able to neutralize the effect that the change in shaft plane has had on the Face Angle and we would see shots that launch straighter and fly straighter. Bad shotsOn both slopes, there were two types of bad shots, ones that flew straight and ones that curved too much, both could get us into trouble. On the slope with the ball above the feet there were five shots that landed more than 20 meters from the Target Line, which is nearly 17% of the Total shots played from the slope. On this slope, there were four shots that landed right of the Target Line, one was due to a severe offcenter strike in the heel of the clubface and the other three were due to the toe of the club digging into the ground at impact which caused the Face Angle to point to the right and the balls launched right and curved further right. 
Uphill & DownhillThe key numbers on these slopes are: Launch Angle, Height, Landing Angle, Carry, Total/Bounce and Roll & Side. FlatWe begin by looking at the key numbers from the flat as these will serve as the baseline for the numbers from the two slopes to come. If we start again by looking at the start of the flight, the Launch Angle, the numbers are higher than the PGA Tour averages but are nevertheless quite consistent with 100% of the twentyfour shots having no more than 2° of difference to the averages of each club. The next part of the flight is the Apex, and again these numbers are higher than the PGA Tour averages but again quite consistent with only 25% having more than a 2 meter of difference to the averages. As the other two numbers were higher than the PGA Tour averages it is no surprise that the Landing Angle is also higher, but again there is consistency in the numbers with less than 9% of the shots having more than a 2° of variance from the averages of each club. I will not mention the Carry numbers as they are only interesting when being discussed with the slope as to the increase or loss in distance, I will however mention the Bounce and Roll for each club and here are the averages both Normalized and NonNormalized. 
Bounce and Roll NonNormalized 
Bounce and Roll Normalized 
Difference  
4 Iron  4.7m  7.9m  3.2m 
6 Iron  2.8m  4.7m  1.9m 
8 Iron  1.7m  3.0m  1.3m 
Uphill
As with the previous slopes we will begin by looking at the start of the flight and working forward. For the Launch Angle, we can see that there has been a significant increase in the averages of the three clubs; the 4iron has 7.1° more, the 6iron has 5.9° more and the 8iron has 4.4° more. So, the longer the club, the more it follows the slope. However, what is impressive is the consistency to these numbers. Less than 6% (1 shot) of the shots from the uphill slope had more than a 1° of variance from the averages, when more than 29% of the shots from the flat did. What is even more impressive is that with the 6iron every shot was less than 0.3° of the average!
Flat Launch Angle 
Uphill Launch Angle 
Difference  
4 Iron  13.1  20.2  7.1° Increase 
6 Iron  17.2  23.1  5.9° Increase 
8 Iron  23.3  27.7  4.4° Increase 
For the Height, we again see an increase in the numbers and again the increase is substantial. For the 4iron the average apex is 10.4 meters higher (37.4%) than from the flat, the 6iron had an apex 8.3 meters (27.2%) higher and the 8iron had an apex 6.2 meters (19.4%) higher. For each club, there was always a shot that flew much lower than the rest but the lowest shot with each club from the slope still apexes higher than the highest shot from the flat. What stands out to me when looking at these numbers is that the apexes from the uphill slope are almost identical: 38.2°, 38.8° and 38.2°, again consistency from this slope and this is after all what this case study is looking for evidence of.
Flat Height (m) 
Uphill Height (m) 
Difference  
4 Iron  27.8  38.2  10.4m Increase 
6 Iron  30.5  38.8  8.3m Increase 
8 Iron  32.0  38.2  6.2m Increase 
For the Landing Angle, we see a severe steepening for each club from the slope, which comes as no surprise because of the increased Height in which the shots were flying. With the 4iron, there was an increase of 5.3°, bringing the Landing Angle to 57.5°; the 6iron increased by 6.5°, bringing the Landing Angle to 60.1°; and the 8iron increased by 7.8°, bringing the Landing Angle to 63.8°. The mean of these numbers is a little over 6.5° and just half a degree from the value of the slope. When we look at the individual shots of each club, the flattest Landing Angle from the slope was as steep or steeper than the steepest Landing Angle from the flat. These Landing Angles from the uphill slope are what we would expect to see when playing into wind.
Flat Landing Angle 
Uphill Landing Angle 
Difference  
4 Iron  52.2°  57.5°  5.3° Increase 
6 Iron  53.6°  60.1°  6.5° Increase 
8 Iron  56.0°  63.8°  7.8° Increase 
As the balls were flying higher and landing steeper I would expect that the shots would Carry shorter, and two out of the three clubs when NonNormalized did and only one of the three Normalized clubs did. Let’s start by looking at the NonNormalized. The 4iron was the odd one out and carried the same (0.3 meters further), and what stood out with this club is that not only were the average carries the same but so too were the shortest and longest shots: 150 .5 and 157.5 meters from the flat compared to 150.6 and 157.6 meters from the uphill slope. The 6iron and the 8iron did lose distance, 5.4 and 10.5 meters respectively.
It is however the difference in the increase that I find interesting. The 6iron loses 5.7 meters compared to the 4iron and the 8iron loses 5.1 meters compared to the 6iron. One of the many patterns starting to arise. For the Normalized, the 4iron and the 6iron had slight gains in distance; 5.3 and 0.3 meters respectively, whereas the 8iron lost a small amount of 4.7 meters. With these amounts of difference to the standard shot from the flat there should be little fear in playing this shot if the Height and curvature are not a problem.
Flat Carry(m) NonNormalized 
Uphill Slope Carry(m) NonNormalized 
Difference Carry(m) NonNormalized 
Flat Carry(m) Normalized 
Uphill Slope Carry(m) Normalized 
Difference Carry(m) Normalized 

4 Iron  154.1  154.4  0.3 Increase 
164.5  169.8  5.3 Increase 
6 Iron  138.0  132.6  5.4 Decrease 
149.5  149.8  0.3 Increase 
8 Iron  119.2  108.7  10.5 Decrease 
132.4  127.7  4.7 Decrease 
Although the Total distance that any shot has in golf is incredibly important, what I want to see here is the difference between the Carry and the Total, which will give us the amount of Bounce and Roll of the shot. If we begin to look at the Total, all three clubs, when NonNormalized are shorter than from the flat but when Normalized only two of the three Totals from the uphill slope are shorter than the flat. Not surprising that their Total was shorter as they had a higher Apex and a steeper Landing Angle, but maybe a surprise that the 4iron from the uphill slope had a longer Total than from the flat.
For the Bounce and Roll with the NonNormalized data, the 4iron lost 0.5 meters, the 6iron lost 6.2 meters and the 8iron lost 13 meters. Then when we look at the Normalized data difference between the Carry and the Total to find the Bounce and Roll there is also a decrease in the amount of Bounce and Roll with the shots from the uphill slope. There though only a small amount of change with the 4iron and 6iron averages where the dropin Bounce and Roll was less than one meter and the averages held true for the individual shots.
However, with the 8iron there was a 2.5 meter drop in bounce and roll and 71% of the shots had negative Bounce and Roll. Meaning that they had enough backspin to make the balls zip back and have a shorter Total than the Carry, this is a huge shift as 0% of the 8irons from the flat did. With the Normalized data, the amount was almost the same, they all had a slight decrease in the amount in the bounce and roll of 0.5 meters (4iron), 0.8 meters (6iron) and 2.5 meters (8iron).
Uphill Slope Bounce and Roll NonNormalized 
Uphill Slope Bounce and Roll Normalized 
Difference  
4 Iron  4.2m  7.2m  3.0m 
6 Iron  2.0m  4.3m  2.3m 
8 Iron  0.8m  1.3m  2.1m 
The last part to this slope is Side, and when we look at the Side there are two sets of numbers: NonNormalized and Normalized. When we look at the NonNormalized data 100% of the shots from the slope finished left of the Target Line compared to 54% of the shots from the flat. The 4iron finished the furthest left at 17.2 meters, followed by the 6iron at 14.8 meters and the 8iron the least with 11.6 meters. With the normalized data, the numbers were similar with again 100% of the shots from the slope finishing left of Target compared to 58% from the flat. The 4iron was still the furthest left with 17.6 meters, the 6iron with 12.5 meters and the 8iron with 10.1 meters. These numbers are very close to what we saw from the previous two slopes, will the downhill be the same?
Flat Side(m) NonNormalized 
Uphill Slope Side(m) NonNormalized 
Difference Side(m) NonNormalized 
Flat Side(m) Normalized 
Uphill Slope Side(m) Normalized 
Difference Side(m) Normalized 

4 Iron  0.5 L  17.2 L  16.7m More Left 
3.5 L  17.6 L  14.1m More Left 
6 Iron  0.7 R  14.8 L  15.5m More Left 
2.1 L  12.5 L  10.4m More Left 
8 Iron  1.3 R  11.6 L  12.9m More Left 
0.6 R  10.1 L  10.7m More Left 
ReasonsThe classic way of playing shots from an uphill slope is to position the body perpendicular to the slope and to have the weight on the lower foot. These adjustments will allow the player to swing up the slope and contact the ball in a similar way to how they would from a flat lie. The drawback of this address position is the shaft will be leaning away from the Target at address and at impact. This leaning of the club away from the Target will increase the Dynamic Loft and cause the higher Launch Angle, the higher Launch Angle coupled with similar Ball Speed and Spin Rate cause the higher ball flight. The higher ball flight leads to the steeper Landing Angle and the steeper Landing Angle with similar Spin Rate will produce less Bounce and Roll. 
Another problem playing shots from the slope is weight transfer. With the weight, so much on the lower foot it is very difficult to transfer the weight to the leading foot and the effect is twofold. Firstly, with less weight transfer and body action through the impact there will be a drop in clubhead speed: the 4iron lost 2.4mph, the 6iron lost 1.5mph and the 8iron lost 1.7mph on the averages for the shots. Secondly, as the body is hanging back on the back foot the club is more likely to pass the hands and close the clubface at impact, each Face Angle was exactly 1.5° more closed from the slope compared to from the flat. These two points explain the loss in distance and why the shots started and finished left of the Target.
Flat Club Speed 
Uphill Slope Club Speed 
Difference  
4 Iron  91.6 mph  89.2 mph  2.4 mph Slower 
6 Iron  88.4 mph  86.9 mph  1.5 mph Slower 
8 Iron  85.5 mph  83.8 mph  1.7 mph Slower 
The numbers didn’t move exactly 7.2°, like the slope, but the adjustments in the setup did produce similar numbers to the flat. The Attack Angle was steeper from the slope, the 4iron was 1.4° steeper, the 6iron was 2.7° steeper and the 8iron was 2.6° steeper but from the slope the Attack Angle was very consistent, with a maximum of 1.1 of variance, true for all three clubs. The Dynamic Loft was more because of the negative shaft lean but the Spin Loft for all three clubs from the flat and the slope was near identical, with a difference of 0.2°, 0.3° and 0.3° of difference, so the adjustments were effective.
Flat Attack Angle 
Uphill Slope Attack Angle 
Difference  Uphill Slope Equivalent AoA 

4 Iron  4.6°  1.2°  5.8° More Positive 
6.0° 
6 Iron  4.9°  0.4°  4.5° More Positive 
7.6° 
8 Iron  5.9°  1.3°  4.6° More Positive 
8.5° 
Lean inWhat if the situation does not allow or you simply don’t want to play a high soft landing shot, is it possible to play a near normal trajectory from the uphill slope? Well the answer is yes, but we need to make some different adjustments to the setup. Instead of positioning the body perpendicular to the slope and having the weight on the lower foot we would need to lean into the slope and the weight would be more on the leading foot. These changes to the setup would remove the negative shaft lean and produce a more positive shaft lean and bring the Dynamic Loft closer to what we see from the flat. This proved to be a very effective way of playing this shot and when we look at the key numbers the results are excellent: The 4iron had a Launch Angle that averaged only 1.2° higher than from the flat and 5.9° lower than with the traditional method, the balls had an Apex that was only 2.8 meters higher than the flat, had a Landing Angle that was only 0.8° steeper, carried 1.5 meters further, had the same amount of Bounce and Roll and finished 3 meters further to the right. The 6iron had a Launch Angle that averaged 1.4° lower than from the flat and 7.3° lower than the traditional method, the balls had an Apex 2.6 meters lower, had a Landing Angle that was 2.4° flatter, carried 4.8 meters further, had 3.3 meters more Bounce and Roll and finished 5 meters further to the right. The 8iron had a Launch Angle that averaged 2.4° lower than from the flat and 7.7° lower than with the traditional method, had an apex 1.5 meters lower, had a steeper Landing Angle of 2.9°, carried 3.5 meters shorter, had 1.5 meters less bounce and roll and finished only 2.9 meters further to the right. If we look at the dispersion chart to the right, we can see that achieved the same results as the shots from the flat lie, except for one rogue shot that made the averages seem worse than the reality. Even though these numbers are so like the flat numbers and the shot dispersion was so small it is a difficult way of playing the shot because of the severity of the impact and this approach is only suitable for the better player. 
Downhill
We have arrived to the final slope of this study, and as with the previous three slopes, we will start by looking at the start of the flight. Launch Angle, there was a huge drop in the angle in which the balls were launching from the downhill slope. With the 4iron the average launch dropped to 1.9°, which is a 11.2° change, the 6iron’s average dropped to 8.7°, an 8.5° change, and the 8iron’s average was 14.3°, a 9° change. These are all extreme changes and this slope has had a much greater effect than the previous three. 100% of the shots from the slope launched lower than from the flat, and by quite some amount, the highest Launch Angle from the downhill slope was considerably lower than the lowest Launch Angle from the flat.
Flat Launch Angle 
Downhill Slope Launch Angle 
Difference  
4 Iron  13.1°  1.9°  11.2° Decrease 
6 Iron  17.2°  8.7°  8.5° Decrease 
8 Iron  23.3°  14.3°  9.0° Decrease 
Flat Lowest Launch Angle 
Downhill Slope Highest Launch Angle 
Difference  
4 Iron  11.1°  5.5°  5.6° Lower 
6 Iron  16.0°  10.1°  5.9° Lower 
8 Iron  21.9°  15.4°  6.5° Lower 
Height, was considerably lower from the downhill slope. The average of the 4iron had an apex of 10.3 meters which is nearly 63% lower than from the flat, the 6iron had an average apex of 15 meters which is nearly 51% lower and the 8iron had an average apex of 16.3 meters which is 49% lower. From what we saw with the uphill slope, we would expect these changes but the degree of change is huge. When we look at the highest apex from the downhill slope and the lowest apex from the flat with each club the severity of change still holds true.
Flat Height 
Downhill Slope Height 
Difference  
4 Iron  27.8m  10.3m  17.5m Lower 
6 Iron  30.5m  15.0m  15.5m Lower 
8 Iron  32.0m  16.3m  15.7m Lower 
Flat Lowest Apex 
Downhill Slope Highest Apex 
Difference  %  
4 Iron  23.4m  11.1m  12.3m Lower 
52.56% Lower 
6 Iron  27.7m  16.8m  10.9m Lower 
39.35% Lower 
8 Iron  30.9m  18.7m  12.2m Lower 
39.48% Lower 
Landing Angle, as we would expect from shots that are flying lower, the Landing Angles from the downhill slope are flatter than from the flat lie. With the 4iron the balls are landing nearly 20° (37.93%) flatter, the 6iron is landing a little over 13° (24.44%) flatter and the 8iron is landing nearly 12° (20.54%) flatter when compared to the flat. Once again, we see that this slope has caused a big change in the way the balls are flying and far away from the 7.45° of the slope. When we look at the flattest Landing Angle from the flat and the steepest Landing Angle from the slope there is still a large difference and still more than the 7.45° of the slope in two of the three clubs.
Flat Landing Angle 
Downhill Slope Landing Angle 
Difference  
4 Iron  52.2°  32.4°  19.8° Flatter 
6 Iron  53.6°  40.5°  13.1° Flatter 
8 Iron  56.0°  44.2°  11.8° Flatter 
Flat Flattest Landing Angle 
Downhill Slope Steepest Landing Angle 
Difference  %  
4 Iron  49.2°  35.1°  14.1° Flatter 
28.66% Flatter 
6 Iron  51.7°  43.1°  8.6° Flatter 
16.63% Flatter 
8 Iron  54.8°  48.0°  6.8° Flatter 
12.41% Flatter 
Carry, 100% of the shots, NonNormalized or normalized, played from the downhill slope Carried shorter than from the flat with the same club. When we look at the NonNormalized data there is a big drop in the average distance for one club and an above average amount for the other 2 clubs, the 4iron lost 28 meters (18.7%), the 6iron lost 11.6 meters (8.41%) and the 8iron lost 11.6 meters (9.73%).
However, when we look at the Normalized data the three clubs lose a much more substantial amount, the 6iron lost 16.4 meters (10.97%) and the 8iron lost 17.4 meters (13.14%) on the average carries. Yet the 4iron still lost a whopping 40.8 meters (24.8%) on its average Carry, it even Carried shorter than the 6iron! When we look at the shortest Carry from the flat and the longest Carry from the slope with each club with the normalized data, there is still a big difference. What is interesting is that 70% of the 6iron shots carried as far or further than the longest Carry with the 4iron.
Flat Carry(m) NonNormalized 
Downhill Slope Carry(m) NonNormalized 
Difference Carry(m) NonNormalized 
Flat Carry(m) Normalized 
Downhill Slope Carry(m) Normalized 
Difference Carry(m) Normalized 

4 Iron  154.1m  126.1m  28m Shorter 
164.5m  123.7m  40.8m Shorter 
6 Iron  138.0m  126.4m  11.6m Shorter 
149.5m  133.1m  16.4m Shorter 
8 Iron  119.2m  107.6m  11.6m Shorter 
132.4m  115.0m  17.4m Shorter 
Flat Shortest Carry Normalized 
Downhill Slope Longest Carry Normalized 
Difference  %  
4 Iron  162.2m  133.5m  28.7m Shorter 
17.69% Shorter 
6 Iron  144.8m  136.3m  8.5m Shorter 
5.87% Shorter 
8 Iron  127.5m  122.0m  5.5m Shorter 
4.31% Shorter 
Bounce and Roll, it comes as no surprise that the shots played from the slope had more Bounce and Roll than the shots played from the flat seeing that the Landing Angle was a great deal flatter. With the NonNormalized data, the amount of Bounce and Roll with all three clubs more than tripled, the 4iron increased by 9.6 meters to 14.3 meters, the 6iron increased by 6 meters to 8.8 meters and the 8iron increased by 3.7 meters to 5.4 meters. With the Normalized data, the same holds true, the amount of Bounce and Roll more than tripled. The 4iron increased by 17.9 meters to 25.8 meters, the 6iron increased by 10.3 meters to 15 meters and the 8iron increased by 7.3 meters to 10.3 meters. In both instances the 6iron and the 8iron and have increased their amount of Bounce and Roll by controllable amounts but the increase in the 4iron’s bounce and roll is becoming uncontrollable.
Bounce and Roll NonNormalized 
Bounce and Roll Normalized 
Difference  
4 Iron  14.3m  25.8m  11.5m More 
6 Iron  8.8m  15.0m  6.2m More 
8 Iron  5.4m  10.3m  4.9m More 
Side, maybe surprisingly the balls flew quite straight. In the NonNormalized data, the 4iron landed 9.2 meters to the right of the Target, which was 9.7 meters more to the right from the flat number, the 6iron landed 1.5 meters to the right, which was 2.2 meters more to the right than the flat number and the 8iron landed 0.8 meters to the right, which was 0.5 meters more to the left than the flat number. When Normalized, the shots finished closer to the Target Line, but the difference was like the NonNormalized data. The 4iron landed 5.2 meters to the right, the 6iron 0.0 meters and the 8iron 0.4 to the right. More than 70% of the shots from the slope finished to the right of the Target Line compared to less than 46% from the flat, showing consistent and playable numbers.
Flat Side(m) NonNormalized 
Downhill Slope Side(m) NonNormalized 
Difference Side(m) NonNormalized 
Flat Side(m) Normalized 
Downhill Slope Side(m) Normalized 
Difference Side(m) Normalized 

4 Iron  0.5 L  9.2 R  9.7m More Right 
3.5 L  5.2 R  8.7m More Right 
6 Iron  0.7 R  1.5 R  0.8m More Right 
2.1 L  0.0  2.1m More Right 
8 Iron  1.3 R  0.8 R  0.5m More Left 
0.6 R  1.0 R  0.4m More Right 
ReasonsThe traditional way of playing this slope is to position the body perpendicular to the slope, to have the weight more on the lower foot and to have the ball closer to middle of the stance. These adjustments are to allow the player to swing down the slope and contact the ball in a similar way as they would from the flat. The effect that these modifications will have on the club is that it will have an excessive forward shaft lean at both address and at impact. This forward shaft lean at impact will reduce the Dynamic Loft and cause the lower Launch Angle, the lower launch combined with lower Ball Speed and similar Spin Rate will cause the lower Apex, the lower flight will give the flatter Landing Angle and the flatter Landing Angle with the similar Spin Rate will produce more Bounce and Roll. Another problem that this setup will produce is, little to no weight transfer, as the body is basically pivoting on the leading leg. The effect that this had was twofold. Firstly, because of the reduced weight transfer and body action through the impact there was a drop in clubhead speed. The 4iron lost 9 mph, the 6iron lost 7.4 mph and the 8iron lost 8.6 mph on the averages of the shots, the mean loss in clubhead speed was 8.3 mph; quite a lot compared to the other slopes. Secondly, with the forward shaft lean it will be nearly impossible for the clubhead to pass the hands at impact with a good shot, so most of the impacts from this slope will have positive Face Angle. In fact, only three shots (11.1%) had a negative Face Angle and of those three only one had more than 0.2°. The dropin Club Speed will account for a large amount of the loss in distance but because the balls flew so low they had no time to Carry before hitting the ground and the more positive Faceto Path will account for the balls finishing more to the right of the Target Line. 
Flat Club Speed 
Downhill Slope Club Speed 
Difference  
4 Iron  91.5 mph  82.5 mph  9.0 mph Slower 
6 Iron  88.4 mph  81.0 mph  7.4 mph Slower 
8 Iron  85.5 mph  76.9 mph  8.6 mph Slower 
Even with all the changes in the numbers, the changes to the setup did their job well and produced similar results to from the flat. The Attack Angle changed very slightly with two of the three clubs: the 4iron had a slight increase of 0.4° and the 6iron had a slight decrease of 0.3°. The 8iron had a slightly larger decrease of 1.7° but that was due to one freak shot where the Attack Angle was 10.3° less than the average as well as having other numbers that were quite different the other shots in the group. The result was however, just like the rest of the other shots in the group.
If we remove this shot from the list, the difference in the Attack Angle was only 0.6° less than the average from the flat. As the Attack Angle didn’t change much but the Dynamic Loft did, there was a change in the Spin Loft, 3.3° with the 4iron, 2.2° with the 6iron and 3.2° with the 8iron, so there was a drop in the Spin Rate of 441rpm and 532rpm with the 4iron and 8iron respectively, but with the 6iron there was a drop of 1220rpm which is an excessive drop and can only be due to the contact slightly higher on the clubface due to the severity of the Attack Angle and as a result of the vertical gear effect they lost Spin.
Flat Attack Angle 
Downhill Slope Attack Angle 
Difference  Downhill Slope Equivalent AoA 

4 Iron  4.6°  12.2°  7.6° More Negative 
4.8° 
6 Iron  4.9°  11.8°  6.9° More Negative 
4.4° 
8 Iron  5.9°  11.4°  5.5° More Negative 
4.0° 
Flat Spin Loft 
Downhill Slope Spin Loft 
Difference  
4 Iron  22.6°  19.3°  3.3° Less Spin Loft 
6 Iron  28.4°  26.2°  2.2° Less Spin Loft 
8 Iron  36.4°  33.2°  3.2° Less Spin Loft 
Comparison
When we look at these slopes Side by Side we can see that they are producing the opposite of each other, the uphill slope was flying higher and the downhill slope was flying lower than the flat. The question is however; have they changed by a similar amount?
Launch Angle, there appears to be quite a difference in the change between the two slopes. For the 4iron, between the flat and the uphill slope there a difference of 7.1°, consistent with the slope, whereas on the downhill slope there was a difference of 11.2°, a difference of nearly 4° from the slope.
With the 6iron, between the flat and the uphill slope there was a difference of 5.9°, 1.3° less than the slope, whereas from the downhill slope there was a difference of 8.5°, 1.3° more than the slope. For the 8iron, between the flat and the uphill slope there was a difference of 4.4°, again a difference of 2.6° less than the slope, whereas from the downhill slope there was a difference of 9°, 1.8° more than the slope. What we see here is that the effect of the slopes is much greater with the 4iron. While with the 6iron and 8iron even though at first glance they appear to be very different they have in fact increased/decreased by a similar amount, 1.3° of difference between the 6irons and 0.8° of difference between the 8irons.
Uphill Slope Launch Angle 
Difference  Flat Launch Angle 
Difference  Downhill Slope Launch Angle 

4 Iron  20.2°  7.1° More 
13.1°  11.2° Less 
1.9° 
6 Iron  23.1°  5.9° More 
17.2°  8.5° Less 
8.7° 
8 Iron  27.7°  4.4° More 
23.3°  9.0° Less 
14.3° 
Height, there was a big difference in the change of the two slopes. For the 4iron on the uphill slope the Apex increased by 10.4 meters but from the downhill slope the Apex decreased by 17.5 meters. For the 6iron on the uphill slope the apex increased by 8.3 meters but decreased by 15.5 meters on the downhill slope. The 8iron from the uphill slope the apex increased by 6.2 meters but decreased by 15.7 meters. There was another difference, whereas on the uphill slope the apex of the three clubs was within 0.6 meters of each other on the downhill slope there was 6 meters of difference between the highest and lowest.
Uphill Slope Height 
Difference  Flat Height 
Difference  Downhill Slope Height 

4 Iron  38.2m  10.4m Higher 
27.8m  17.5m Lower 
10.3m 
6 Iron  38.8m  8.3m Higher 
30.5m  15.5m Lower 
15.0m 
8 Iron  38.2m  6.2m Higher 
32.0m  15.7m Lower 
16.3m 
Landing Angle, again a big difference between the two slopes. The 4iron from the uphill slope had a steeper Landing Angle of 5.3° whereas from the downhill slope the Landing Angle flattened by 19.8°, a 14.5° difference. The 6iron, from the uphill slope had a steeper Landing Angle of 6.5° whereas from the downhill slope it had a flatter Landing Angle of 13.1°, a 6.6° of difference. The 8iron, from the uphill slope had a steeper Landing Angle of 7.8° whereas from the downhill slope it had a flatter Landing Angle of 11.8°, a 4° of difference. Again, we see that the downhill slope has had more effect on the flight of the ball than the uphill slope, particularly with the 4iron.
Uphill Slope Landing Angle 
Difference  Flat Landing Angle 
Difference  Downhill Slope Landing Angle 

4 Iron  57.5°  5.3° Steeper 
52.2°  19.8° Flatter 
32.4° 
6 Iron  60.1°  6.5° Steeper 
53.6°  13.1° Flatter 
40.5° 
8 Iron  63.8°  7.8° Steeper 
56.0°  11.8° Flatter 
44.2° 
Carry, two out of the three clubs had a big difference. For the NonNormalized numbers, the 4iron, on the uphill slope the Carry increased very slightly by 0.3 meters but from the downhill slope it lost 28 meters (18.17%). The 6iron, from the uphill slope lost 5.4 meters and on the downhill slope lost 11.6 meters and for the 8iron, on the uphill slope it lost 10.5 meters and from the downhill slope it lost 11.6 meters. For the Normalized numbers, there were huge differences.
For the 4iron on the uphill slope it gained 5.3 meters yet it lost 40.8 meters from the downhill slope, the 6iron from the uphill slope carried the same amount (0.3 meters gain) but lost 16.4 meters from the downhill slope and the 8iron lost 4.7 meters from the uphill slope and lost 17.4 meters from the downhill slope. From the uphill slope, there was a change in Carry with but no more than a club of difference however with the downhill slope it was always more than a club of difference and in most cases, closer to two or more clubs of difference.
Uphill Slope Carry NonNormalized 
Difference  Flat Carry NonNormalized 
Difference  Downhill Slope Carry NonNormalized 

4 Iron  154.4m  0.3m Longer 
154.1m  28.0m Shorter 
126.1m 
6 Iron  132.6m  5.4m Shorter 
138.0m  11.6m Shorter 
126.4m 
8 Iron  108.7m  10.5m Shorter 
119.2m  11.6m Shorter 
107.6m 
Uphill Slope Carry Normalized 
Difference  Flat Carry Normalized 
Difference  Downhill Slope Carry Normalized 

4 Iron  169.8m  5.3m Longer 
164.5m  40.8m Shorter 
123.7m 
6 Iron  149.8m  0.3m Longer 
149.5m  16.4m Shorter 
133.1m 
8 Iron  127.7m  4.7m Shorter 
132.4m  17.4m Shorter 
115.0m 
Bounce and Roll, two out of the three clubs have a notable difference when NonNormalized and all three have a notable difference when Normalized. If we start with the NonNormalized, the 4iron from the uphill slope only had 0.5 meters less bounce and roll but from the downhill slope the amount increased by 9.6 meters. With the 6iron from the uphill slope the amount decreased by 0.8 but increased by 6 meters from the downhill slope. The 8iron the amount decreased by 2.5 meters, having a shorter Total than Carry, but increased by 2.7 meters on the downhill slope, so only a 0.2 meter of difference in the change. With the Normalized, the 4iron from the uphill slope lost 0.7 meters and increased 17.9 meters from the downhill slope. The 6iron from the uphill slope lost 0.4 meters but increased by 10.3 meters from the downhill slope, and finally the 8iron lost 1.7 meters from the uphill slope but increased by 7.3 meters from the downhill slope.
Uphill Slope Bounce and Roll NonNormalized 
Difference  Flat Bounce and Roll NonNormalized 
Difference  Downhill Slope Bounce and Roll NonNormalized 

4 Iron  4.2m  0.5m Less 
4.7m  9.6m More 
14.3m 
6 Iron  2.0m  0.8m Less 
2.8m  6.0m More 
8.8m 
8 Iron  0.8m  2.5m Less 
1.7m  2.7m More 
4.4m 
Uphill Slope Bounce and Roll Normalized 
Difference  Flat Bounce and Roll Normalized 
Difference  Downhill Slope Bounce and Roll Normalized 

4 Iron  7.2m  0.7m Less 
7.9m  17.9m More 
25.8m 
6 Iron  4.3m  0.4m Less 
4.7m  10.3m More 
15.0m 
8 Iron  1.3m  1.7m Less 
3.0m  7.3m More 
10.3m 
Side, the only result where the downhill slope was desirable. For the nonnormalized shots, the 4iron on the uphill slope landed 16.7 meters more to the left but only landed 9.7 meters more to the right from the downhill slope. The 6iron from the uphill slope landed 15.5 meters more to the left but only 0.8 meters more to the right from the downhill slope and the 8iron from the uphill slope landed 12.9 meters more to the left but only 0.5 meters more to the right from the downhill slope.
For the normalized data, the 4iron from the uphill slope landed 14.1 meters more to the left and 8.7 meters more to the right from the downhill slope, the 6iron landed 10.4 meters more to the left from the uphill slope but only 2.1 meters more to the right from the downhill slope and the 8iron landed 10.7 meters more to the left from the uphill slope but only 0.4 more to the right from the downhill slope. This is the only part of the key numbers where the downhill slope appears to be more under control than the uphill slope.
Uphill Slope Side(m) NonNormalized 
Difference  Flat Side(m) NonNormalized 
Difference  Downhill Slope Side(m) NonNormalized 

4 Iron  17.2 L  16.7m More Left 
0.5 L  9.7m More Right 
9.2 R 
6 Iron  14.8 L  15.5m More Left 
0.7 R  0.8m More Right 
1.5 R 
8 Iron  11.6 L  12.9m More Left 
1.3 R  0.5m More Right 
0.8 R 
Uphill Slope Side(m) Normalized 
Difference  Flat Side(m) Normalized 
Difference  Downhill Slope Side(m) Normalized 

4 Iron  17.6 L  14.1m More Left 
3.5 L  8.7m More Right 
5.2 R 
6 Iron  12.5 L  10.4m More Left 
2.1 L  2.1m More Right 
0.0 
8 Iron  10.1 L  10.7m More Left 
0.6 R  0.4m More Right 
1.0 R 
Overall, apart from the Height of the shot, the uphill slope which might cause some problems in certain situations on the course it is very playable and even offers a way to produce straighter shots that fly in a very similar way to from a flat lie. The downhill lie doesn’t offer any versatility; it is a difficult shot; it must be treated with respect and played accordingly. Its only saving grace is that it flies quite straight, so accept its limitations and play the shot accordingly.
Thoughts
All four slopes were consistent in the results that they produced and we saw that the Side slopes produced incredibly similar results to one another, however in most cases the uphill and the downhill did not. The fact that the downhill slope was the only one of the four slopes that didn’t offer an alternative to the traditional way of playing the shot shows just how difficult this shot is, and the reason that it doesn’t offer a variation is due to the way you must attack the ball.
I believe that for this very same reason, it is the odd one out in the numbers. As the club is approaching the ball from a very steep angle, a mean Attack Angle of 11.8°, there is only the top third of the ball exposed to the club which takes away any possibility of approaching the ball in a different way. Whereas from the other three slopes, particularly the uphill slope, all the back of the ball is exposed to the club allowing for some margin of error or manipulation of the impact, depending on the level of the player.
Answer
The answer to my first question is; yes, they are predictable. In fact, I would go as far as to say very predictable. From this study, I have also more confidence in the way in which I play these slopes as the data has proved that the changes to the setup do exactly what they were supposed to do. The study has however raised a few more questions for me though:
 If the slope is halved or doubled, will the numbers do the same?
 What effect would the roll on the clubface of a hybrid or fairwaywood have when played from these four slopes?
So as much as this study on slopes is over, understanding the slopes is just beginning.
Superb article. Do you have any recommendations for how casual golfers should factor slopes into their distance equations?
Let’s say we’re talking about a slope of say, 7 degrees and a required total distance of 170 yards. I would previously have applied the logic of “uphill lie = 1 club lower (e.g. take a 6 iron instead of the usual 7)” and “downhill lie = 1 club higher (e.g. take an 8 iron instead of the usual 7)”. However, your figures suggest that on a downhill lie I’ll still be ~3 metres or so shorter total distance with the 7 iron so I either need to hit that harder or club up to the 6 iron.
Also, when it comes to side slopes, how is Path affected? Am I more likely to Fade from a lie where the ball is below my feet, or is the ball going to follow my usual shape and just end up more to the right? Apologies if you’ve covered this already, my brain is a bit befuddled by some of the terminology :)
Thank you for your comment and I am glad that you liked the article.
It is always difficult to make recommendations for individuals without seeing their data or ball flight, but lets give it a go!
Firstly, if you are hitting a middle iron 170 yards, with is a very good distance for these clubs i will work on the idea that you have a nice mid ball flight and strike the ball consistently.
For the Side slopes there was little loss in carry distance (through the air), up to half a club and the ball landed as normal. so there is no there is no real adjustments to make for club selection more attention must be paid to the alignment to the right or left to allow the ball to curve towards the target.
For the Upslope, there was a difference of +/ of 5 yards of carry distance, so no real need to make more than a 1 club change and swing comfortable. The positives to this shot is that the ball will fly high and soft, so when the ball lands, it should stop very quickly. Again alignment, should be the main concern to allow the ball to curve back to the target.
The Downslope is a bigger problem, the loss in distance of between 1520 yards on this slope would need generally 2 clubs more to make the carry but the problem is that the ball will land flatter than normal, meaning that the ball will bounce and roll around 1015 yards. SO you will have to be aware of the hazards around the green and play to an area with the most space. 7° slope was not severe with the othere 3 slopes but for the Downslope it is, it must be treated with respect and you shouldn’t ask too much from it.
On the Side slopes the path will change, but only slightly. With the ball below your feet the ball should start more to the right and have a slight fade.
I hope this answers your questions, but if not or if you have anything else to ask please let me know.