Jumps in a rally car: why "flat and short" is taught, what is supported and what is not, and how you approach it with pace notes and an instructor.
The honest answer: In a jump the car leaves the ground, usually at a crest. Coaches teach that jumping flat and short is faster and spares car and body: briefly lift off before take-off and straight back on the throttle. That is school knowledge. We cannot support it. We found neither a study on the benefit of "flat and short" nor one that shows it spares the back.
What is supported is the strain. In a survey of 13 professional and 105 amateur rally competitors, complaints of the lumbar spine (70 percent), cervical spine (54 percent) and shoulders (47 percent) were most common. Co-drivers complained more often about the neck than drivers, drivers more often about hands and wrists [1]. The authors attribute this to vibration and shocks in the rally car [1]. A jump takes such shocks to the extreme, which is practical knowledge.
That is why we deliberately give no copy-it instructions here. The topic is safety-critical, the technique belongs in the hands of an instructor, and on public roads it is prohibited.
Realistically: this is a pro skill. Most hobby drivers never need it.
Crests must sit securely, and your pace notes must say for every spot what comes behind it. Ask yourself honestly: have crest, pace notes and co-driver run without surprise in training?
Milestone: All crests of a stage run without surprise, over several runs.
Look at the jump on foot beforehand: take-off, distance, landing, surface. Write down how you recognise the spot. You must know the landing before you jump.
Milestone: You describe the landing zone and how you recognise it.
Discuss with the instructor the "flat and short" concept, that is why he briefly lifts and goes back on the throttle before the car takes off. This technique is taught but is not backed by studies. The instructor decides when you may drive it.
Milestone: You can restate the concept in your own words without trying it alone.
The first jump is the smallest your stage offers, at the lowest speed that the instructor releases. The landing counts more than the distance.
Milestone: A calm landing, no damage to the car, no pain for either of you.
After each jump check the car (suspension, tyres, underbody) and ask driver and co-driver how the impact felt. Then discuss whether you take the next step or go back.
Milestone: You decide together, with reasons, whether to continue.
Before the jump do not ask "Can I make it?", but "What is my plan if the landing goes wrong?". Whoever has no answer does not jump. That is coaching practice. How much the body has to endure is shown by the survey of 118 participants [1]. Write the answer into the notes so your co-driver knows it too.
Coaches teach that it is faster and spares the car. That is school knowledge. We found no study that supports the benefit.
That cannot be shown. What is supported is only that back complaints are very common among rally competitors: for 70 percent of respondents they affected the lumbar spine [1].
No. On public roads, races and grossly reckless driving are punishable under section 315d of the German Criminal Code [2]. Practise only on closed-off, approved stages with an instructor.
There are no reliable data on that. When crests, pace notes and co-driver work without surprise and an instructor agrees, the next step is conceivable.
As a rule no. As a hobby driver you gain more with secure crests and good pace notes.
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