By Eric Ahlstrom

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Qualifying a new hot wing for next months race, the world flips
over as you see what’s left of your wing fold and depart the airframe…
(Bill Skliar: Formula 1, 1988)

The Problem

In racing there are two types of people, those that have crashed and those that will. Some of those that have yet to crash will retire before the odds catch up with them. In most motorsports, crashing and surviving is considered part of the game. Death is not common, and survivable crashes outnumber fatalities by huge factors.

This is not true for air racing. Emergencies are common, and most end in a dead stick landing and an uninjured pilot. A number of these come in off the runway, and injuries are typical due to the high landing speeds of most racing aircraft. Impact energy goes up with the square of the speed, so terrain, rocks, and a less than flat approach combine to create a bad situation. Any major airframe failure or fire can mean an uncontrollable crash and a dead pilot. It is this type of crash that we need new technology to address.

We are confronted with some interesting attitudes on safety in air racing. Some listen to new ideas and say, "That’s fine for cars-boats-etc., but it’ll never work in air racing" or "It’s too expensive-heavy-bulky". These are valid criticisms that must be addressed for any new technology to make the transition to the unique demands of air racing. There are also those who criticize the whole idea of pilot escape based on not wanting the plane to impact uncontrolled into a crowd or the incredible idea that crash structure can be made to protect against impacts over 200 mph.

By definition, a crash that a pilot would make a conscious decision to leave the aircraft is going to be uncontrolled. No pilot wants to leave an expensive airplane to certain destruction if there’s any chance of saving it. So we continue our examination of escape systems with the firm knowledge that we are not going to see a bunch of pilots blow out of controllable aircraft with no regard to where the wreckage goes. If they are in any way able to they will ride their aircraft to a controllable crash or point it where it won’t do any harm.

Crash Structure

Pulling up after a close race, you’re grateful to get this rough running Griffon back on the ground. Plenty of altitude and airspeed for a wide approach. Then the engine seizes and all six contra rotating blades go flat. Too much drag, too far away, and you’ve got no way to get out of this thing in time. A final call on the radio as the desert rushes up to meet you…

(Steve Hinton: Red Baron, 1979)

Crash structure saves many lives in all sorts of motorsports. Driver encapsulation and energy absorbing structure has radically increased the survival rate in everything from Formula 1 cars to Unlimited Hydroplanes. Could this be used in air racing?

Sadly, the crash speeds of air racing prevent physically possible crash structure from handling anything more than a ground loop or belly landing. Impact forces go up with the square of the impact velocity and down in direct proportion to the deceleration distance; i.e. the depth of the crash structure. In aircraft we don’t have space to put the several feet of crushable structure around the pilot that is common to race cars.

Many point out that car drivers survive crashes at over 200 mph; however all of the survivable crashes are glancing blows where the actual impact speed is much less. Even NASCAR, with their 2,000 lb. safety cages, has suffered fatal crashes where the impact was abrupt or head on. These fatalities have occurred at speeds as low as 100 mph. The spectacular spinning flip that looks horrifying actually spreads the energy out over multiple impacts and a long period of deceleration. In spite of breakaway parts and three feet of crash structure, any straight hit on a wall at over 150 mph will kill a driver due to excessive G loads.

In years past, hard barriers outside of road courses caused many deaths at even lower speeds. In the last twenty years, the volume of crushable structure required for safety has exceeded the size of the cars. This is being addressed in ground based motorsports with large run off areas, catch fences, and energy absorbing walls. The first two allow cars and motorcycles to decelerate and the latter provide crushable structure and depth at the point of impact. None of this is practical for air racing. We simply can't cover the desert with foam rubber.

Steve Hinton combined a virtually flat impact and some strategically placed boulders to stay straight and tear off parts of the airplane without the cockpit meeting a sudden stop from ~170 mph. If those boulders had been moved a couple of feet, the fuselage would have hit them before the wings and that would have been it. Dissipating energy by shedding parts in a planned fashion is basic to auto racing design, but the Red Baron disintegrated safely by luck and not design. The pilot still suffered serious injuries.

We should pay attention to the way an airframe will break up if it sustains a survivable impact, and crash structure sufficient to protect a pilot in a low speed forced landing is within the weight and space limits of Unlimiteds and potentially other classes of racers. Energy absorbing pavement for runway overruns has been developed and could help with fast and long landings under adverse conditions. But impact speeds over 150 mph combined with any significant sink rate will create G forces that the pilot just can’t survive. So we have to get him out of there.

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Accident dramatizations have been included to help the reader understand what a pilot goes through during a potentially fatal emergency. Most of the accidents listed in these articles resulted in major or fatal injuries to the pilot. It is the opinion of the author that some, perhaps most of these injuries could have been prevented with the pilot extraction system technology described.