Gideon Yampolsky

Thank you :-)

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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.

March 2022 Gradually all technical issues were found and resolved. But system did not started in air yet. I reached inevitable conclusion that I cannot resolve it like this. While standing on the launch shelf, I was in need to know exactly what is happening with the engines. Did they receive start command ? Did they properly responded ? At what stage they failed and what is the reason ? Engines are advanced stuff. They have integrated computer which controls them. Computer sends reports in real time. I needed to read, process and display these reports. So I decided to develop “dashboard” mounted on my helmet, to display what is going on. Engines reports are complicated. It is not for “ok / not ok” LED indicator. You need computer with high resolution display, and you need to write program which communicates with engines and displays information in comprehensive form. If such thing to implement, it worth to add barometer, GPS, and recording memory, so full flight computer will be implemented. The need of computer was known from the beginning of the project. I estimated that it will take 12 – 18 months to design it including software. It is a lot of time and huge delay for the project. I therefore hoped that first powered jumps will be made without it, and I will implement it in later stage. But the situation was that without computer I could not make a progress. Surprisingly it went faster than I originally estimated, “only” 6 months of work … Prototype tested in lab – Computer display installed with the system on the test bench

January 2022 After endless changes, improvements, fixes, trainings of pilots, damages (at certain point paraplane engine failed and we have to replace it - just one of many issues we faced), and discussions with Israeli Aviation Authority, everything was in place for first powered jump. Well, it did not happen … The system refused to run when in air. I made about 10 attempts over period of several months. There was always the same pattern – system was fully checked at workshop, then it was ran on the ground right before takeoff. While everything on the ground was perfect, all attempts in air failed. I stood on the launch shelf, gave engines start command, and … nothing happened. After landing and back in workshop I checked everything and found the reason. One time it was a damaged component in control handle, next time it was malfunctioning cable, next time discovered that I forgot to open fuel valve, next time it was something else. Issues were hiding on the ground, patiently waited until I’m in air and then showed up. As issues were resolved, new ones popped up. One by one I cleaned them. Some issues were more destructive: Results of one of failed attempts. Engines began start sequence, but due to inaccurate position on the launch shelf jet partially hit the shelf and bounced, damaging the wingsuit. I cut damaged parts, and using new fabric rebuilt (sewed) it to the original shape. 2 weeks of work. After repair it was looking more or least as original. I jumped to test it without engines, it was flying perfect. Good. I’m still flying that wingsuit with engines. I also purchased one more ATC from Squirrel, so now I have backup. I then changed shelf design to assure that jet exhaust will go cleanly into the air. Other “interesting” case: We climbed up, I stood on the shelf, give engines command to start, nothing happened (as usual), attempted several times to restart. Then I returned to passenger seat, checked everything I can, stood again on the shelf, tried to start engines, nothing happened. Then, frustrated, I jumped. I understood that engines will not run, but decided at least to check once again how it flies, down. But … attempt to start engines took time, this was prolonged attempt, and … or shit … we did not pay attention that we drifted a lot. Only after the jump I discovered that I absolutely have no idea where I am, and even don’t know what is the direction to landing area. I glided in circles, choose open field and landed. After landing I checked by phone where I’m. 16 km from landing area. In uninhabited place with no roads. It took 4 hours of complicated rescue mission to pick me up from there.

February 2021 Humm … Nobody was ready to take me up ! There are 3 skydiving clubs in Israel. I spoke with all their managers (one of them is my good friend), but it did not work. Israeli airspace is highly congested and heavily regulated. Launching something experimental from the plane requires permits which seemingly impossible to obtain. Clubs did not want to risk their license. I then tried discuss it with hot balloon operators. Same result. I considered rising up by unmanned drone. Well, uncoordinated, in Israel, most probably it would end up by being hit by Patriot missile … Searching for solution was long zig-zagging path. Eventually, only one real option left – paraplane (powered parachute vehicle), with many modifications. So I needed to buy paraplane, learn to fly it, modify it for high altitude and wingsuit launching, find and train pilots who ready to take me up, find how to obtain permits for this. It took 8 months. Paraplane being built in workshop in Israel. Many special modifications were made in order to make it suitable for climbing to high altitude and safe launching of wingsuit jump. We equipped it with powerful Rotax 914 engine, not typical for such kind of vehicle. First version of launching pad. This initial version was modified many times until it has become sufficient for safe jump. Paraplane being tested by manufacturer - High altitude test flight More advanced version of launch pad being mounted on the vehicle

January 2021 I mounted engines on the boots. Added starter battery. Designed and assembled interface circuits, so it became complete system. On the ground system was running perfectly. So, I thought that system is ready for first powered flight. LOL It took another 2.5 years until that happened …

October 2020 Fuel container. I considered many options of container - on the back, or small containers on sides, etc. Finally I decided that container will be on the torso. I thought that it has to be flexible, to match torso movement. Container was implemented as fuel bladder surrounded by ribbed aluminum enclosure and nylon fabric. Fragments of the enclosure - I lined the enclosure with rubber, to protect the bladder. First I prepared small bladder, to test welding method - Actual bladder, 12 liters - Preparation of cover fabric - Almost final, first version - Design and build of the container was a lot of work. After container completion I tried to attach it by zippers to the wingsuit, but found that this attachment was not stable enough. I then prepared harness worn on the body and attached the container, through wingsuit, to the harness. And eventually I have to test it in flight … Note that chest strap of the skydiving rig just goes around it, but has no function in keeping it in place. The container is attached to body harness. I first jumped with container empty. On the next jump I filled it with water to imitate fuel weight. The first jump with the container was preceded by strong anxiety. I did not know what to expect from that big bump on the chest. But in air it behaved perfectly. It did not add any annoying feeling and did not create any difficulties to flight. Canopy deployment, opening and landing also felt quite normal. Good ! Currently (year 2023) I already have two containers, which both have similar dimensions, but different thickness. The capacity of thin container is 6 litters, and capacity of thick one is 12 liters, which supposed to be sufficient for 8 minutes of flight. This is newer design of 6L container –

For Jet Dragon Project I'm using Winx 210. Soft landings. Also, there is 8 mm rubber sole at the bottom of engine mountings.

September 2020 Next I needed control handle – to start and stop engines, and control their thrust. It has to be ergonomic and easily accessible while in flight. First I built several dummy prototypes from cardboard – And the final version – Later, in 2023, I had to completely redesign its concept …

August 2020 Engine mountings should be tested, but I did not want to use real engines for the test, as it could damage them. So I prepared dummy “engines” from plastic buckets filled with weights, for total 13 Kg. And I jumped with it – So far so good !

May 2020 I needed to check that it is possible to carry weight on the foot when flying wingsuit. Combined weight engines, boots, mounting brackets and starter batteries is 13 Kg . My concern was that it will pull legs down and I will stall. I checked it by series of wingsuit jumps while I'm gradually increasing weight attached to the foot. First I attached 4 Kg of weights (packs filled with iron pellets). Jumped, felt normal. Good. Then attached 8 Kg. With 8 Kg I stalled heavily - it was fall rather than flight. On the next attempt I de-arched in order to keep correct pitch and was able to fly wingsuit normally again. Good. Seems that it would be possible to fly with turbines attached to the feet. I had find how to attach the turbines . Key concern was about torsional stress they will apply – their thrust will tend to bend the ankle sideways. Some kind of support was required to avoid it. First “research” version of how to resolve it – I found that tracking shoes did not provide sufficient ankle support. Snowboard boots were better idea – Which leads to implementation looking like this – Engine mounting angle is 18 degrees. In wingsuit flight, legs are stretched apart, this will make thrust vector to be in match with flight direction.

LOL, you are right, it happened. Had to work hard to calm them. Now I'm more careful regarding running engines in neighborhood.