If you go to the hardware store you can get cable cable clamps and some pulleys and make a more accurate scaling set up. The pulleys can change the location of your scale as well as anchor point. With the cable and clamps you can arrange your sled more friendly to accuracy.
Amazing! Hopefully one day I can make that too. Where did you get all the information to make this? I'm still surprised how you balanced this rotor, last time you said you just balance.it on a stand.. but how about axial unbalance?
Hi Oliver, I bought a balancing machine for little money. You can see it in one of my last videos. I have a good guy, who is smarter than me for a lot of calculations😉Thank you! Andy
Hi Oliver, For the used machine I paid 750€ and its von LOS Losenhausenwerk. I didnt find anything in the Internet, but there is a good Din A4 folder manual with the machine👍 Andy
The hill is alive with the sound of jet thrust! Was doing some armchair calculations on what your compressor PR might be in regards to the temperature differential, but wondered what your ambient temp was on your test day. Seems like she's a little down on power though. At any rate, it's always a good day when she runs!
@@Praendy Yeah, seems like you may have some leaking from your combustion liner or flow is reversing course as that seems awfully high for a relatively low ratio (20.5ish psi?). When's the last time you had it all apart?
Ich bin sehr froh, dass ich Deutsch lerne, weil ich ihre Videos ohne Subtitles verstehen kann. Ich habe viel videos über ,,Diesel-turbo jet engines" gesehen, aber ihre ,,axial-flow homemade jet engine" Projekt habe ich vorher nicht gesehen und finde es sehr interessant.
Hi, great video as ususal. Is it possible that force reading of the scale is off by small value due to axis of the scale not being parallel to the axis in wich the engine is exerting its force?
Hi, You are right, the scale is not in thrust line. For comparing some results it is enough for me. I am always in trouble, when the afterburner is installed and the scale starts to melt. Thats why I put it lower in a save distance. Andy
@@Praendy thanks for replying. I see the problem with the scale meltdown and do understand that it is a difference in thrust that is important for you, not the absolute values. If you want to tackle it in a future, replacing scale with load cell or using pulleys creatively might give you those absolute values. But your time is better spend actually playing with a fun staff as balancing the turbines or designing articulated afterburner nozzle. And big thank you for publishing your build log it is very inspiring.
I wonder what kind of exhaust velocities you're getting, and what the intake temperature might look like given some facisimile of airspeed. Surely you'd get higher combustion pressure and a higher throttle ceiling if you had more air flying into the intake? More importantly, can it bypass!
Hi Alex, ich berechne schon einfache Dinge wie Querschnitte, Belochung usw, aber die grundsätzlichen Dinge wie Massendurchsatz, Druck, Schub, Winkel habe ich noch nicht drauf. Ich arbeite dran😉 Andy
Currently you're running with a centrifugal compressor, right? Any chance you're gonna build an axial-flow engine? I think all the home builds I've seen have been centrifugal compressors and I'd like to see someone make an axial-flow engine
It’s not necessarily desirable to run 3-4 bar….it might be depending on the operating conditions. In particular, you need a sufficient pressure ratio to extract enough energy from the turbine to power the compressor. You need enough pressure ratio to get a suitable exhaust velocity to actually get thrust. There are several problems with making the problem that simple: If you run the compressor at a point less than maximum efficiency, you need even more turbine power to drive it. If you run the turbine at a relatively poor efficiency point, you need more thermal input to get the required power. As a result, the minimum energy consumption to make an engine start and/or idle are not necessarily the points you’d run at for thrust. At idle you need not have pressure since the goal isn’t to produce thrust. The third problem is that you can’t run the compressor too close to surge. With a fixed nozzle, for a given set of components, there exists at least one best efficiency point, and it is likely not at maximum mass flow rate. In fact, given static and total pressures, and temperatures from the correct locations in the engine, and it’s mass flow rate, it’s possible to create instrumentation giving real time efficiencies for components. One other less than obvious thing to point out…it’s possible to operate an engine in a range where a waste gate type mechanism found on automotive turbochargers can’t prevent over speed situations. It may on one side of an operating point, but may not function as intended on the other side. Looking at a compressor flow map, with wheel speeds, you can see situations where where speed doesn’t correspond well with pressure ratio, and that there exist points not distinguished solely by pressure and temperature calculations. (With a state machine knowing where you were and passed through, it’s possible, but compressor surge would invalidate assumptions and a state machine in a protective control system isn’t without design risk. Being hot film mass air flow sensors cost little, and only eat one analog input, it’s an easy tradeoff to make in my opinion. A proper fuel control and protection system really requires a wheel tooth sensor, optical tachometer or some other direct method to measure shaft speed. The upside to integrating controls is over speed protection, reduction in hot start stress, sequencing fuel and ignition and single lever thrust control. There is more to unpack here than at first glance.
Axial thrust of the engine must be higher than 18 kg @ 1.4 bar. Real thrust value is equal to 18 kg / Cos α (while α is the angle between rotor and chain directions) 🙂
