Sergey Voskresensky Sergey Voskresensky
Each of us from time to time turns his car into a truck. Cottage, travel, moving, repairs … And some have delivery of goods to small retail outlets. Of course, most drivers feel “heavier” car reactions, inertia of brakes or the changed work of suspensions, not to mention the increased fuel consumption. But it is interesting to express some of these sensations in numbers. How exactly does a change in mass affect car behavior? Where to wait for a dirty trick, braking on a floor from 100 km / h or sharply twisting a wheel when avoiding an obstacle?
“Lada Granta” is a mass car typical of its class, and it’s also a novelty. Well, the Citroen-C5 with the latest generation of hydroactive suspensions (Hydroactive III +) was chosen as its full antipode.
STRENGTH WITHOUT GRAVITY
Before measuring the longitudinal dynamics, you will have to add about two centners to the curb weight of the cars: these are two people (driver and instrument) and measuring equipment. We consider this mass basic.
Correctly and clearly "hang out" the car - half the battle
Correctly and clearly "hang out" the car - half the battle. Correctly and clearly "hang out" the car - half the battle.
The obvious minus of the “Grants” is the lack of anti-lock braking system. And the heavy and inert brake pedal and overheating of the mechanisms already at the third braking from 100 km / h brought to nothing initially positive emotions. With difficulty they got 47 m of the minimum stopping distance. Most cars usually fit in 40–42 m.
It’s a pity, because in other disciplines Lada Grant is very good. Flexible and easy to lift engine, elastic, energy-intensive suspension, reliable handling. The steering wheel, however, bites a little about “zero” (a feature of the electric power steering), and the feedback is so-so. But in general, the budget car was noticeably more interesting than originally expected. The result (see table) is very good even against the background of foreign cars. Another thing is that at the reshuffle, the everyday ease of communicating with Grant is quickly disappearing. With an increase in speed, rolls also grow, and reactions become heavy. But the marginal speed of the maneuver is high. And the behavior is quite stable, no surprises.
At the Citroen-C5, its active suspensions are constantly looking for some optimal level of the body above the ground and cannot find it at all. Only the “Sport” mode saves from motion sickness: oddly enough, it is he who finally allows you to feel the entire comfort of a smart chassis.
A car with almost two tons of “set-off” weight easily fits into the conditional norm of the minimum stopping distance (40 m). And he does it from the first three or four attempts. "Grant", which is almost twice as light, for the "test" 47 m it took 12 brakes and jewelry work while driving.
This is not drag racing. An overloaded trunk unloaded the drive wheels, so the car reacts to the gas pedal like that
This is not drag racing. An overloaded trunk unloaded the drive wheels, so the car reacts to the gas pedal like that. This is not drag racing. An overloaded trunk unloaded the drive wheels, so the car reacts to the gas pedal like that.
As for handling, I had to tinker a bit with the Citroen. During sharp maneuvers, a non-deactivable stabilization system (ESP) comes into effect very early, confusing the driver and independently correcting the trajectory. But when you finally get used to the features of this system, you quickly find a common language with the machine. At the rearrangement, C5 shows a decent result, being also extremely obedient and solid in management.
We load cars to the authorized full mass. With the appearance of mannequins bubbling with water in the rear seats and additional ballast at our feet, the behavior of the machines clearly changed. “Lada Granta” immediately lifted its nose, at once losing its former lightness. Citroen, on the contrary, even improved its already excellent ride. At the same time, the ground clearance remained at the same level. Here it is, the triumph of science and the "Hydroactive"!
Look at the tables (open in full size on a mouse click):
As the load increased, both models became slower by about 2 s in acceleration from standstill and when measuring elasticity. True, in the last nomination, the Citroen, equipped with a machine gun and a diesel engine, lost less. But at maximum speed he lost ground, unlike the Grants.
But the most important thing is to come: how are they slowed down and controlled?
With the brakes of the loaded Lada Grant, trouble! The braking distance increased by 4.5 m is a serious drawback. And this is the result of several of the best attempts at us, the testers. And with a normal driver, everything can be much worse. At C5 "Hydroactive" competently redistributes the load on the wheels and axles. Only tens of millimeters of loss to yourself, and this is at full load! Impressive!
At the rearrangement of the suspension, the laden Citroen earned even better than a half-empty car. Especially the rear, now actively helping the driver. As a result, the stabilization system began to interfere more gently. And C5, as they say, went. With rolls, with a squeal of tires, but as tenaciously as if he had not received any makeweight. Bravo, Hydroactive!
A noticeable roll at the rearrangement is most likely caused by the triggered stabilization system, which braked one of the wheels
A noticeable roll at the rearrangement is most likely caused by the triggered stabilization system, which braked one of the wheels. A noticeable roll at the rearrangement is most likely caused by the triggered stabilization system, which braked one of the wheels.
With the “Lada Grant” a miracle did not happen. The steering wheel has become light and less clear - a kind of indicator of the unloaded front axle. The reactions became more thoughtful. The rearrangement is prevented by delays associated with banks and the fact that the rear axle has ceased to help the driver. The “Grants” noticeably increased understeer: with a sharp turn of the steering wheel the car “thinks” much longer. The result is a loss to oneself of about 4 km / h and a noticeably increased load on the driver: now you have to turn the steering wheel oh-hoo with such speed and scope! And this is not only a decrease in top speed, but also errors that lead to loss of control. In addition to the anti-lock system, the Grant would not hurt … no, not an active suspension, but a simple stabilization system.
RESULTS AND RECOMMENDATIONS
So, the heavier the car, the more difficult its behavior, especially in critical situations. Citroën, with its clever Hydroactive, is the exception rather than the rule. The most insidious thing is that an overloaded car, as a rule, is able to drive fast, but it will be so-so driven and braked.
But the owners of "Citroen" with hydropneumatics can rejoice. Stunningly stable driving with and without load - compensation for the frequent cases of Hydroactive’s premature failure on our roads. Apparently, the perfect solution is somewhere in between. Not for nothing that pneumatic elements are increasingly being built into the suspensions of modern cars …
And one more thing: driving with a full load, especially a long one, requires increasing the pressure in the tires of both axles. If the car has a corresponding plate, then according to it, if not, add 0.2-0.4 bar to the base.
ZR MEASUREMENTS: WEIGHT CHARACTERISTICS
MEASUREMENT SP: WEIGHT CHARACTERISTICS MEASUREMENT SP: WEIGHT CHARACTERISTICS
In fact, nothing has changed, the mannequins remained in place, but a significant part of the ballast (200 kg) migrated to the Grants trunk. Life option: people have a full salon, in addition, things must be captured. How the front axle unloaded is visible even with the naked eye. How does it feel while driving? If you do not make sudden movements, you will feel the difference only in the excessive slipping of the drive wheels. But at the rearrangement, the car at first does not react to the steering wheel in any way, but then it starts wagging backwards so that you just hold on. Therefore, it is better to distribute the load in the cabin as evenly as possible.