In 45 seconds, what can you do? Can you skydive between two planes that are in a 140 mph nose dive, regain control, and avoid the final hard stop at the end?
The amount of time the pilots have to do it is the basis of Plane swap, the latest and possibly maddest world-first feat from the Red Bull Air Force aviation team. Digital Trends spoke to the engineer in charge of modifying the aircraft that will be used in the endeavor about making it a reality.
It's a pretty difficult challenge, said Dr. Iscold, before continuing with a laugh.
Iscold is the type of person you want on this project. He has a doctorate in mechanical engineering and has designed and built airplanes since 2001. His enthusiasm for Plane swap and aviation in general shone through during our conversation. This is not the same as what he has done before.
My background is in race airplanes and breaking records, but this is about how we slow down the airplane. That was a challenge. Two people swap airplanes during flight and that is very frightening. We see the small pieces that allow us to get there, not the big picture. That is how you make this crazy thing not be crazy.
The development and fitment of a special speed brake and a custom autopilot system are two engineering challenges that stand out. We talked about these aspects during our conversation.
When we first talked, I thought the speed brake would be smaller than what we have, and that it would be on the wing.
The speed brake is essential for the planes to have a controlled nosedive, not just to maintain the 140 mph target speed, but also for stability. The use of speed and air brakes in aviation is not new, but it is the first time it has been used in this area.
He said it was five times larger than he thought it would be. It is attached to the landing gear and another hard point in front of the fuselage, and it uses the same technology as a helicopter.
The landing gear on the plane works as normal despite the fact that it is being added to the plane. In 30 minutes, the entire section could be removed and the airplane would be back to standard.
There were a few additional challenges to fitting a giant flat structure to the bottom of the aircraft. Iscold solved the problem of buffeting by adding holes to the speed brake, which allows air to pass through it and break down the turbulence that threatens stability. The speed brake is made up of four pieces, and the plane wouldn't pass a 70 degree dive during the first flight tests, because it needed to be 90 degrees.
It took a while to figure out what was going on, even with more test flights and simulations. The team discovered that the speed brake has a low-pressure area behind it. The plane's tail is in the flow and that is forcing it to pitch up. The two were fighting.
The solution was simple, we created a gap between the fuselage and the speed brake, so the air flowed through it, and that jet of air protected the tail from the flow of air.
Iscold compared this to a modern Formula One car, where a section of the rear wing lifts to reduce drag. It means that a 90-degree nosedive can be achieved safely and reliably on the Plane swap planes.
Plane swap is a challenge because of the speed brake. autopilot needs to take over because each aircraft will be left unattended for a period of time. Plane swap requires the autopilot to do the opposite of keeping the plane level and maintain a nosedive. Iscold explained that a normal autopilot isn't suitable as all its usual reference points become meaningless in that 90-degree dive. We went to the same system that rockets use, as they operate at 90 degrees.
The plan to be successful had to be worked out with the differences in speed and size of the objects involved. It is about 10 miles an hour. They will move around with the wind. If you change the angle by just four degrees, the plane will go straight down at 140 mph. The surface level is small when the wind hits the skydiver, but large when it hits the airplane. The autopilot needs to be within three degrees of pitch to make the trajectory stable for the skydivers.
It is important to remember that there are two planes and two skydivers having to deal with this. They are independent. The autopilot works to keep the pitch and heading correct when we are doing the dive, because we adjust them to behave in the same way. You won't see it with the naked eye, but they're diving on a path to stop them hitting each other.
There are always unexpected problems to solve because there is no set of guidelines to follow for the plane design. On the day we spoke to Dr. Iscold, the team had been battling with one plane behaving differently from the other. Both planes are the same.
The blue plane dives straight as a dart. It's perfect. Iscold said that the silver airplane is a nightmare and never tracks correctly, apart from one slight difference on the tail.
The team changed the size of the speed brake, but it wasn't enough to replicate the blue plane. This makes the plane go faster and it becomes harder for the skydivers.
Iscold found the problem after further examination. We are playing around with this and it makes a difference. It's obvious when I say it, but because the project is so large and complex, we lost track of it.
The blue plane was developed to be the same as the silver plane. Problems like the center of gravity are hard to pin down, as flight tests are logistically complex, as a large enough airfield is always required, along with the skydivers and testing equipment, and concern that should something go wrong, it may mean losing a plane. Iscold said that it takes time to solve problems and that it requires a steady approach.
Let's go back to the time when the skydivers had to jump from one plane to the other in 45 seconds.
When you break it down, the time between the initial dive and the recovery is shorter.
30 seconds is all it takes to skydive between two rapidly descending aircraft. It sounds too short, but Dr. Iscold isn't worried. They have enough time for a second try if they miss the first one.
The two brave skydivers undertaking this exciting feat have been made to feel like they have 45 seconds to do it.
You will be able to see the outcome of Dr. Iscold and his team when the Red Bull Plane swap takes place on April 24. It will be live-streamed on Hulu in the U.S. at 7 p.m. The time is either 4 p.m. or 5 p.m. At the same time, on Red Bull TV.
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