Tennis has been at the forefront of ushering sports into the computer age. Smart tech designed to improve your skill level is now easily accessible to professional players and those less serious about the game. This includes everything from sensors that attach to your racquet and monitor shots, to robots that vacuum up tennis balls saving you time and hassle.
Essential reading: Tennis gadgets and trackers to improve your game
Just when we though we’d seen it all, another innovative gadget has launched to prove us wrong. Now you don’t even need a live opponent to practice with!
Slinger is a high-tech portable tennis ball launcher that comes in the form of an oversized tennis bag. A few years in the making, the product has its origins in successful Kickstarter and Indiegogo campaigns which raised a combined total of over $1 million. After a few delays in manufacturing, the product has now been made available for purchase to all (US distributor; UK distributor).
“We had this crazy idea that quickly became a core mission for us: that everyone should be able to own a tennis ball launcher,” the company behind the gizmo says.
So they got to work.
The bag can hurl balls in your direction at speeds up to 45 miles per hour. You control the speed and the gizmo can be set to launch shots at a variety of angles and elevation modes.
The ball launcher has definitely generated lots of interest amongst aspiring amateurs and hobbyists. It even has the endorsement of legendary tennis coach Nick Bollettieri and all-time greats the Bryan Brothers.
The coronavirus lockdown measures have relaxed somewhat in the UK. This allowed me to head over to the tennis courts with my new tennis partner. Here’s what I made of it after a month of use.
How to use
The bottom line
Slinger comes across as a blend between a big tennis bag and a nice looking suitcase. The whole thing feels very nicely made and of robust build quality. Its weight comes in at about 33 lbs (excluding tennis balls), but you’ve got a handle and pair of sturdy wheels down below so you can pull it along as a trolley. I wouldn’t suggest carrying it on your shoulders.
The ball launcher is very portable. It may be higher than the competition but it is lighter. You’ll struggle to find a quality tennis ball machine under 40 lbs and they can go as high as 99 lbs for their big counterparts. Not to mention that they definitely do not look as nice! In a “zipped-up” state, there’s no clue Slinger Bag is a tennis ball launcher.
You can put things in it such as tennis racquets, water bottles, towels and more. There’s a variety of functional pockets including a deep one at the top which holds the bigger items. Another pocket can be found on the left side and one more on the right. The last one even has a USB port for charging your smartphone while practicing. Nice touch.
You also get the option of purchasing a little unit that secures to the handlebars to hold your smartphone. This way you can film yourself practicing.
Right below the main storage area is the Hopper Pocket. This is where the tennis balls go. Underneath is the feeder plate and mechanism which pulls the balls down into the shute and slings them out. For optimum performance the company suggests you fill the hopper with 72 tennis balls, although the maximum capacity is 144 (when the hopper is open).
During use I actually found 72 to be a nice number. It offers an enjoyable blend between practice and time spent gathering the balls. What I didn’t expect was that the job of picking up the balls would give me such a physical workout! To make things easier, Slinger also sells a telescopic ball pick-up tube. This attaches nicely to the bag and will help a bit. But I did find some of the balls don’t slide easily out of the tube which can be a bit frustrating.
Control panel and battery
The brains of the unit are down below. Unzip the front cover and you’ll notice the control panel. On the left is the space behind which the battery sits, the right has a couple of dials.
The top dial goes from Beginner to Advanced – this controls the speed of the balls. The maximum you can get is around 45mph or 72.5kmph. The bottom dial has the same settings. That one controls the feed rate – or how often the balls come flinging towards you. This ranges from 2 to 10 seconds.
On a full charge the battery will give you around 5 hours of playing time which is quite good. Typically, I would take it to the court for a 2 hour session and upon returning home would plug it into an electricity outlet. It would then recharge in about an hour or two, although refueling from zero to max can take up to 6 hours.
When the battery is fully charged the power is reduced to an occasional ‘pulse’ to protect its life span. The company suggests you make sure to plug Slinger into an electricity outlet at least once a month to ensure optimum performance of the battery.
On the bottom right hand side of Slinger is another zipper. Open this and you’ll see a little handle which allows you to control the trajectory of the ball. This offers a choice between 10 and 40 degrees of ball elevation. I would typically set it to around 10 or 15 unless I was practicing overheads or serves in which case I opted for 40.
Slinger Bag also comes with an Oscillator. This is sold separately or in a bundle. You are meant to place it under the ball launcher. This moves the unit from left to right to give you a bit more of a workout.
If you are buying Slinger, I actually suggest you include the oscillator as it makes a big difference. The oscillation does not randomly hit short and deep balls, but it will force you to return balls fired in all directions of the court. This way you can work on backhands and forehands, as well as your footwork.
Finally, you also get a little remote which provides basic start/stop functionality. It comes with two separate buttons – one for the launcher, the other for the oscillator. Both of these work quite well, even if you are at the far end of the court.
It’s actually a very sensible move that the company has opted to include a remote. When you think about it – if something is about to start hurling balls in your direction at speeds up to 45 mph, it is best you are not standing right in front of it!
On a court Slinger Bag can be set up to do its thing within one minute. I would typically position it just inside the baseline as this provides nice depth of shots. Having said that, Slinger is easily moved on the court so you can experiment varying court placement to find what works best for you. There’s lots to experiment with as you can change the placement, speed, angle and ball frequency.
Before proceeding, let’s put things into context, I’ve played tennis perhaps once or twice a week for about 10 years. So I consider myself to be an intermediate player but not a beginner or advanced.
Groundstrokes, overheads, volleys, serves
Once you’ve positioned the ball machine switch it on by pressing the physical button on the control panel. You’ll hear a beep indicating Slinger Bag has powered on. This doesn’t actually start the launch mechanism, it just powers the thing on.
You can use Slinger with or without the oscillator. To use the oscillator, you’ll actually have to lift Slinger and place it onto the plastic oscillating unit. This then plugs into the control panel for electricity power. You’ll hear a faint sound after a few seconds and notice the oscillator moving (along with the ball machine) from left to right.
As far as settings, when using the ball launcher I would typically opt for the high-intermediate level for speed and low intermediate level for ball feed. This flings the ball quite deep into the court forcing me to return them from around the baseline. I found that the setting roughly correlates to the level of player I typically come up against in match play.
When it comes to frequency, the feed setting mentioned above means a ball would come my way every 4-5 seconds. I found this to be quite comfortable giving me enough time to prepare and focus on the next shot.
This is, of course, for ground strokes. The angle I would opt for is around 10 degrees, sometimes 15 if I wanted to practice putting away balls. Around 10% is what I would opt for volleys, as well.
After you’ve tweaked the speed, feed and angle use the remote to switch on the ball launcher. You will hear a beep, followed by another beep a few seconds later. It is after the second beep the launch mechanism will start.
One thing to point out is that there is no way to control the spin of the balls. Every ball has a top spin. This gives the effect of speeding up the ball when it bounces on the court reducing the time you have to react. Which makes a difference as the balls are more challenging to return.
The effect is more pronounced at higher speeds so one way of controlling the amount of topspin is by altering the ball speed. Altering the elevation angle to find a launch sequence that works best for your game is another way.
The top spin means you really have to be focused and step into the ball and hit it early. Which is what you should be doing anyway so its good practice.
But this does make it less useful for doing volleys because all you get are dipping volleys which can be quite difficult to control. Having said that, you do get those types of shots during match play so they are good to practice. But it’s really great for groundstrokes, overheads and other types of shots.
At times I would ramp up the speed to the maximum available setting of 45 mph. As mentioned, the higher the speed the greater the top spin effect which made these balls quite challenging. Beginners would really struggle at this setting but high-intermediates and advanced players would find it good practice. It’s not exactly Rafa Nadal level, but it feels close.
My one worry was whether the gadget would be loud. After all I do not want to be drawing attention to myself or disturbing players on nearby courts. And I’m glad to report that it is not. At the high intermediate level there is a slight whirring sound but if you’re on the opposite end of the court you will hardly hear it. It does get a bit louder at the top setting.
This is a very versatile machine. The fact that you can control the angle of the ball means that opting for 40 degrees allows you to practice overheads. Once again, you will need to focus as the spin of the ball makes them more challenging than they seem at first glance.
Finally, also worth mentioning is the Ball Boy mode. This is simply when you lower the feed to a slower setting, reduce the speed down to the minimum and increase the angle to the maximum 40 degrees. Position Slinger a few meters away from you and it will lob balls in your direction every few seconds allowing you to practice serves.
Tennis balls and tennis ball jams
I haven’t said much about the tennis balls. Slinger can be purchased with Trinity Wilson balls which I found work slightly better than other brands. They have a unique plaster material that extends their lifespan. Wilson says Trinity Balls last four times longer than other tennis balls.
During practice, I actually used a combination of 72 Trinity Wilson balls and 8-10 old tennis balls from other brands. This provided a nice variety as the used tennis balls didn’t fly out as much so forced me to run forward at times.
It’s also worth saying a few things about ball jams. Having used it for a month I would estimate that a ball jam would occur perhaps once every 300 balls. This is at the intermediate setting. At the advanced setting it occurs a bit more frequently. You will find these numbers typical for even the more expensive brands. When a ball jam occurs, simply switch off Slinger and remove the ball. It’s a 5 second job.
As part of Gadgets & Wearables I’ve tested everything under the sun when it comes to high tech tennis gear. Smart tennis racquets, swing tracking wristbands, smart racquet dampeners and even a GoPro like device that detects in real time whether a ball has landed inside or outside the court. You name it, I’ve tried it. And in my opinion, Slinger is the most practical of the lot as it has the most potential to improve your game.
To advance your skill level you need to do drills and repetitions. Without that you are going to stagnate. And practice and time spent on court is the key. Slinger provides you with a practice partner you can always count on, who will never be late or grumpy. You could even say it acts like a tennis coach.
The ball launcher works well, it looks great, you can fit a lot of tennis balls inside and you can customize everything to your level of play. As far as speed and spin of the balls – I think it will suffice most players. I actually found the oscillator makes a big difference as it forces you to return balls fired in all directions.
Is Slinger perfect? No. I would have preferred it if you could control the spin of the ball a bit more. The product is large, but its very portable and allows for great storage capabilities – not just for balls but also racquets, water-bottles, etc.
Tennis ball machines are one of the most effective and fastest ways to improve your game. But most of these are very costly. Slinger Bag is designed to allow almost anyone to own a decent tennis ball launcher. Best of all, it looks nothing like a tennis ball launcher!
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