- Serpent F110 SF2 - Review -

WORDS & PHOTOS BY LITO REYES


PERFORMANCE TEST 1/10-SCALE ELECTRIC F1 CAR | KIT

On track with the Snake’s newest F1 machine


If there is one team whose name is synonymous with championship on-road cars, it’s Serpent. With a history going back to the 1970s, Serpent cars have earned nine World Championship titles and national titles in Europe, the Americas, and Asia that are too numerous to count. The past few years have seen Serpent enter an aggressive new-product development cycle that includes F1 cars and the latest open-wheeler tested here: the F110 SF2. This 1/10-scale electric car is designed to compete with the venerable line of Tamiya F1 cars and, at first glance, is spec’d similarly: RWD, 190mm width, floating rear pod. But by taking a closer look, details emerge that make the car almost undeniably a Serpent. Former IFMAR (International Federation of Model Auto Racing) World Champion and Serpent co-owner Michael Salven has been designing and racing Serpent cars since the 1990s. He designed the F110 SF2 to be compatible—out of the box—with all the different rules used around the world for 1/10 F1 racing while still focusing on realism and performance—certainly no small feat. Let’s see what the result is.

SLIDING KINGPIN OR “FRONT FLEX” SUSPENSION

Some racing series specify only the use of sliding kingpin front ends, while others allow any setup. The F110 SF2 includes parts to use three different types of suspension, depending on what is allowed in your racing program: a traditional sliding kingpin setup, a flexible lower A-arm setup (which Serpent calls the “front flex” option), or an advanced flexible lower A-arm with damper tubes. Out of the box, you have the choice of building the car with the first two options. I opted to use the traditional setup because it is known to work on asphalt of varying conditions. Both box setups use the 2.5mm lower arm plate. If using the sliding kingpin suspension, the lower arm plate is firmly mounted to riser posts. If the front flex option is used, the plate mounts to the ball joint to allow it to flex and pivot up and down. In either case, hard, molded composite upper arms locate the kingpins, and a carbon brace holds keyed inserts for accurate and repeatable caster adjustments.


Left: The tried-and-true sliding-kingpin-front-suspension setup works great on rough surfaces. Right: The lower arm plate is firmly mounted for use with the sprung kingpins, but it can also be set to bend for the “front flex” option.


TRIPLE-PIVOT REAR SUSPENSION

The F110’s rear suspension uses a central pivot to allow the rear axle to move vertically and roll side to side. To keep the pod and axle perpendicular with the chassis’s centerline, trailing links extend from the chassis to meet pivots on the sides of the pod. An oil-filled shock absorbs and damps jolts, and has a threaded aluminum body for easy preload adjustments and a threaded ball-cup adjuster for tuning the length. Its bladderless design and dual seals make it easy to bleed and keep the oil in. An aluminum damper tube controls roll movement and features machined grooves in the rod as a reservoir for the damping fluid. A spring on each side of the damper-plate assembly helps the rear pod return to center after a twisting motion.


TEST GEAR - Airtronics Super Vortex Zero speed control

The Super Vortex Zero can handle sensored motors down to a 3.5T on a single-cell LiPo or a 4.5T motor with a two-cell LiPo pack. I combined the Super Vortex with the Airtronics RX-427 receiver to take advantage of the brand’s SSL [Q: spell out SSL?] protocol, which allows the speed control’s settings—including drag brake, throttle sensitivity, and timing advance, among other features—to be changed remotely when paired with the Airtronics M12, M12S, and MT-4S radios. In addition to remote setting changes, the SSL setup allows telemetry data—including battery-pack voltage, motor rpm, speed-control temperature, and motor temperature—to be displayed at the transmitter without the need for additional sensors on the car.


A precision rear shock, with threaded adjusters for both preload and length, smoothly supports the rear end.





BELLCRANK STEERING WITH ADJUSTABLE ACKERMAN

The in-line, flat-mounted steering servo can be affixed to the SF2 in either forward or rearward orientation, depending on how much weight you want on the front wheels. A molded center bellcrank rides on ball bearings for smooth action, and has an insert that can be mounted two ways for your choice of Ackerman setting. The kit comes with both a rigid servo arm and a servo saver. I always recommend using a servo saver as it not only protects the servo in a crash but also the steering components. Watch your endpoint settings when setting up the steering system; there are no travel stops, and the front wheels will rub the suspension arms if you dial in too much travel.


The center-mounted bellcrank rides on ball bearings for bind-free action.


HIGH-PERFORMANCE FRONT AND REAR WINGS

Serpent includes front and rear wings that emulate the modern F1 designs. But they don’t just look the part; they are adjustable and can help tune handling characteristics. Up front, there are multiple elements, including a large surface rear wing that can be adjusted in three different positions. Likewise, in the rear, there are three horizontal elements that support the vertical sideplates, with the highest element being adjustable in three positions. The front wing is made out of flexible nylon, capable of withstanding front-end collisions, while the rear wing is made out of a stiff composite to prevent deforming.


The adjustable rear wing is made out of a stiff composite to keep its shape at speed, while the front wing is made out of flexible nylon to resist crash damage.




ALUMINUM AXLE AND REAR POD

From its looks, the rear pod is all about strength and precision. The lower plate and upper brace are made out of the same 2.5mm carbon stock as the main chassis. Aluminum sideplates, finished in a deep gunmetal gray, house the keyed inserts that support the rear-axle assembly. To finish off the pod’s frame is the rear bulkhead, made from extrathick 3mm carbon plate. The rear axle is made out of lightweight black anodized aluminum and has the inner differential housing permanently attached. Also made out of aluminum finished in gunmetal, the outer housing and hub pieces are thick and run perfectly true. The left-side hub clamps onto the axle—no crosspins to lose or bend. The differential comes with a 68-tooth, 48-pitch spur gear; it is externally adjustable by inserting an Allen wrench through a hole in the hub, but it does require the removal of the rear right wheel. Hardened differential rings with a ground surface come standard, which key to the differential plates to eliminate ring slippage. An extensive number of molded inserts are included to allow for fine-tuning of rear ride height.


Strong yet lightweight carbon and aluminum parts make up the rear pod. The rear axle is made out of black anodized aluminum and has a low rotating mass. The differential uses readily available and durable 48-pitch gears and comes with 1/8-in.-diameter steel differential balls.


BEHIND THE WHEEL

My primary test location for the F110 SF2 was the URC V Raceway in Northridge, California. It is a temporary parking-lot track with a 150-foot-long back straight and a technical infield designed to challenge electric racers. Because the SF2 doesn’t come with a body, I opted to use the PROTOform F1-Fourteen shell, made to emulate the 2014 Sahara Force India VJM07 driven by Nico Hülkenberg, with the help of a decal set from F1 R/C Lab. Although the Serpent front wing mounts about half an inch forward of most other F1 cars, I was still able to mount the PROTOform body on the chassis without issue. And I was pleased that the Serpent front wing actually resembled the one that Force India used last year.

Once I started bringing the SF2 up to race pace, I found the car to be stable at top speed, but it also pushed more than I prefer in midspeed turns. High-speed sweepers were satisfactory as I could use the power from the SchuurSpeed motor to carry speed throughout the turn by drifting the car. But tighter turns, especially when transitioning back on the throttle, were compromised. To improve handling, I set toe-in from zero to one degree of toe-out. The effect on the track was noticeable as I was able to use more throttle in the tight turns, bringing my lap times down. This, fortunately, didn’t take away much of its straight-line stability, and adjusting the wings for more front downforce and less in the rear further improved handling.

I was pleased to find that the GRP mounted tires, which are also broken in from the factory, wore nicely and didn’t overheat, even during a long session on a 135-degree track surface. For my next session, I brought a few sets of front springs and some fluids to play with. Adding softer springs in front made a big difference, but adjusting the caster for more aggressive steering was too much for my taste. On top of that, I firmed up the rear damping by going up from the 30K fluid with which I built the damper to thicker 50K fluid; this slowed down the rear-pod action to force weight transfer to the front end. With further tuning, I expect the SF2 will be as competitive—if not more so—than my other F1 cars. The only trouble I had during my test and photo sessions with the SF2 was with the front wing. The heat of the sun-baked track appeared to soften the front wing; even a small tap on a hose or board would tweak the wing enough that I had to bring it into the pits. On a cooler day, the wing held its shape better.




FINAL WORD

Rest assured, Serpent’s on-road reputation is intact with the F110 SF2. The kit offers a robust chassis with lots of tuning flexibility as well as features, like caster and Ackerman inserts, that make it easy to accurately replicate settings. The materials on the SF2 are of the highest quality, and no compromises appear to have been made in the transition from design to the finished product. Little details—such as the thicker rear bulkhead on the pod, the thumbscrews for the battery retainer, and the sculpting on the front-end aluminum posts—show attention to both design and function. And if you add the adjustability it has, there should be no track situation that it can’t handle. The F110 SF2, with its race pedigree, durability, and performance potential, is a car that can stand up to any F1 car on the market.


+ “Front-flex” and traditional front suspension setups come in the box
+ Bind-free rear pod design
+ Easy differential adjustment

- Front wing is too flexible
- Steering system does not have travel stops


SOURCES:
Serpent Model Racing Cars, distributed by Serpent America, serpentamerica.com
Airtronics airtronics.net
F1 R/C Lab f1rclab.mybigcommerce.com
GRP Tyres grpgandini.it
Hobby People hobbypeople.net
PROTOform racepf.com
SchuurSpeed schuurspeed.com

VEHICLE SPECS
Item no.: F110 SF2
Scale: 1/10
Price: $287
Weight, as tested: 2.2 lb. (1014g)

CHASSIS
Material: 2.5mm carbon-graphite laminate
Type: Pan

SUSPENSION
Type (F/R): Sliding kingpin/flexible lower plate or floating rear pod

SHOCK
Body: Threaded aluminum
Shaft: 2mm steel
Volume compensation: Foam

DRIVETRAIN
Type: RWD direct drive
Spur gear/pinion: 68T 48-pitch/pinion not included
Differential: Adjustable ball type
Axle: .025 in. aluminum
Bearings: Metal/rubber shielded

WHEELS &TIRES
Not included

TEST GEAR (NOT INCLUDED)
Transmitter: Airtronics M12
Receiver: Airtronics RX-472
Steering servo: Airtronics 94647
Speed control: Airtronics Super Vortex Zero
Motor: SchuurSpeed Extreme SPEC 21.5t V3
Battery: Hobby People 2S 4000mAH 60C Shorty
Body: PROTOform F1-Fourteen
Tires/wheels: GRP S2 compound belted premounts


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