Gideon Yampolsky

Thank you :-)

x.mp4

So far I tested it with engines on the ground and without engines in flight. I still need to make several small modifications and practice jumps before jumping this new version with jets.

From April to August 2023 I made 10 attempts of powered flight. Only four of them were successful – engines started and run until all fuel was consumed. In other six jumps engine start issues rendered the attempt unsuccessful. One of engines was slow to start, until my flight altitude become critically low. After three consecutive fails in August I decided to take a break and focus on problem's solution. First I discussed it with engines manufacturer. They indeed confirmed that engine takes significant time to start, and they have no means to make it shorter. Next I tried to feed the engines with more flammable fuel, hoping that higher flammability will make it start faster. I replaced diesel with Jet-A fuel, which has 30% benzine. I was perfectly aware that something so flammable in intimate proximity is very bad idea. But at least I had to know if it works. Fortunately it did not work. Engine's start time did not improve. The best solution was to start engines prior to the jump, as in such case it doesn’t matters how much time it takes. But they cannot start in vertical position when I’m standing on the launching shelf. I therefore had to redesign the launching shelf.

One of my friends, pilot who took me up for jet test jumps, was killed in terrorists attack 10 days ago. He is one of 1300 civilians which were murdered in one morning

During the entire flight RPM was 97,000 which is turbines' maximum. As you can see in Flysigh recording horizontal speed was not constant. This because I was experimenting with body position. When I increased pitch (i.e. tried to “fly up”) I lost some of horizontal speed but managed to achieve level flight and even climb up a little bit. My conclusion after experiments is, that with engines thrust, the optimal flight characteristics are different than in the case of regular wingsuit. Optimal flight speed with ATC wingsuit is around 150 Km/h. But with engines I found that optimal speed is around 110 Km/h, in body position aiming to “fly up”. I’m planning to experiment more in future. But prior to further flights I have to make significant changes in some of system components, which will take time. Sadly saying Israel went through horrifying event 10 days ago, which drew us into an unexpected war. So currently we have completely different priorities.

Results so far ... 6L of fuel consumed. I'm still learning how to fly it efficiently jet_powered_ws.CSV

Thank you. Actually I preferred to do everything myself, it was more difficult but also more rewarding. So far I made several successful flights, and they are getting better and better. Once I will feel they are good enough I will publish video and flysight. Presently I'm aiming to 8 minutes flight.

Thank you for nice feedback. And don't feel bad about chicken house, I ran into similar situation with my aquarium, and technical capabilities did not help :-)

Thank you. I'm still learning how to fly it efficiently. Will film it then.

April 2023 Right on the ground problems began. Barometer chip malfunctioned - my dashboard display did not show altitude readings, and no climb / descend rate. Anyway I decided to proceed. I can judge the altitude visually. I run the system on the ground. Okay. We took off, climbed to 11,000. I stood on the far end of the shelf. Commanded engines to start. They responded properly. As they reached the state “Accelerate” … I jumped. OMG The initial feeling was like there are two persons working together on common mission. I was busy to stabilize and fly wingsuit. Engines were busy to start themselves. Throwing short glimpses on the display, for my surprise and satisfaction, I noticed that they are making progress toward full operation. At certain point engines reported full run, 30,000 RPM. From that point I can control them. I then increased throttle. 50,000 RPM. 70,000 RPM. 95,000 RPM ! Gentle but powerful force on my foot pushed me forward ! I changed body position to fly up. In regular flight wingsuit will climb a little-bit, then will lose speed and stall after a few seconds. But now it was not the case. Despite climbing up I definitely continued to fly forward at significant speed. It worked ! Without altitude readings, I decided to keep larger safety margins, not to fly until the last moment. So I gradually decreased RPM and eventually shut down engines. Changed flight pitch to pre-opening, deployed PC and landed perfectly.

January 2023 Almost there. The last aborted attempt. That one was expected. During previous attempts I already understood that the design concept of control handle is not correct. Although during wingsuit flight it was convenient enough, it was nearly impossible to use it while standing on the shelf. Another related problem was that in cold temperature on January at 11,000 feet my fingers froze even if I wore thick glove. I couldn’t operate handle’s buttons. We climbed up, I stood on the shelf, but I could not operate control handle. Decided to abort. Better safe than sorry. So I completely redesigned control handle concept. Moved it to left hand and attached to the palm rather than to wingsuit. Then it was possible to wear mitten over it, so fingers would not freeze. I again built several prototypes, until finding optimal solution. I changed buttons and throttle functions, to be able to operate it with just pointer finger inside mitten.

November 2022 So I built pivoting test bench which enables engines to be operated vertically or horizontally, and enables to change the orientation quickly. On test bench it became clear that indeed engines cannot start vertically. They are okay to pass initial pre-heating states in that orientation, but after about 20 seconds they must be in horizontal position, otherwise the startup will fail. Okay, got it. That means I cannot wait on the shelf until engines start, but rather have to see on display that they began the process and then jump immediately.

October 2022 The reason could be too high altitude – low air pressure and cold. Engines start is specified by JetCat up to 9000 feet. I attempted to start them at 11,000. As well it could be anything else. I dismounted everything from the wingsuit and prepared dedicated shelf to take the entire system up mounted on the shelf. I then climbed to 11,000 and gave engines command to start. They did not start. I repeated, reading computer reports. They reach certain state of ignition sequence and then failed. I took the vehicle down to 8000 feet and repeated. Same results. Lowered the vehicle to 3000, and then to 1000 feet. Nothing. So, clearly it is not due to high altitude. The only remaining explanation was than they unable to start when vertically oriented. In all ground tests engines always were oriented horizontally.

September 2022 Computer was installed in wingsuit, created its own long series of secondary issues to resolve, but eventually became essential and critical component of Jet Dragon system. It provided reports about engines status and helped to find and resolve issues. And it helped to clarify, once and for all, that even when everything is okay, engines are not ready to start. They began warmup and acceleration, but could not reach running conditions, and eventually they shut down.