prototype RC turbofan, two-spool
 

Two-spool turbofan.
AgentJayZ also comments.

The fuel tank is 2.5liter (absinthe, grenadine??).

The designer/builder wrote that fuel consumption is high(er) because too much fuel was used to lubricate the bearings:
www.rc-network.de/forum/showthread.php/727090-Effizienteste-Turbine?p=4754549&viewfull=1#post4754549

Static thrust a little over 12kg, the core is KJ66 based (8kg):
translate...www.rc-network.de/forum/showthread.php/727090-Effizienteste-Turbine/p=4755001

Channel
www.youtube.com/channel/UCvdOgVvlsngJ9oTP4BVckfA

Cool. Some day that may become the standard where space allows, as long as the weight reduction from improved efficiency significantly exceeds the weight and complexity gained via the fan. Either way, we should applaud the research effort IMO.

Vriendelijke groeten ;) en wees voorzichtig, Ron
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130N on a KJ-66. Drop mike.

Strange that a 80 N turbine can produce 130 N running a fan. Considering the losses and running two turbine wheels and then some planetary gearbox or the like for the fan takeoff. Yet you are somehow able to almost double the original turbine core output.

I am assuming the TF-200 would have something to do with the inlet diameter, then if that is that case to get 130 N you would need around ~ 10K W of power to the fan just off the top of my head.

Pretty sure your going to get a lot less than that from a 66 core.

Regards,

The original turbine will be limited in power by rpm, the bigger swept volume of the turbo fan will create more thrust for less rpm.

Actually as per the first rule you cannot get more out than actually went in initially. Yes the fan maybe be more efficient and the turbine use less fuel yet it would be difficult to get more thrust than you got in the first place. RC turbines are very inefficient due to the size, turbines do get more efficient as they get bigger. As per your comment you will have more thrust with less rpm, so your turbine output (KW) would be even lower than it was initially as igt is running a lower rpm.

So you for instance you have a shaft turbine that produces 10kw, then you have a generator connected to that. You could get 8~9KW or 80~90% efficiency back out, there are your losses. more parts, gears etc the losses increase.

So as above you would need at least 10+kw from the turbine in the first place to run a 200mm fan to get 150N, also you would have little residual thrust from the turbine as again it is all a closed loop.

It is also getting to the point whereas EDF's are getting to the point of mass power in a very efficient setup. Brushless motors at 90% running straight fans are putting out massive thrust, Vasyfan have a 570mm that is in the 150kg range which is amazing, 250mm fans running 55kg pretty awesome.

Regards,

The typical model turbine exhaust produces 100KW plus in waste heat. A downstream turbine or turbines can extract a lot of that energy, typically for a small turbine about 150 deg C per stage x massflow. So there is a lot of scope for fan power.
Turbine engine efficiency post combustion is all about recovering heat.

You're forgetting turbines are not 100% efficient; much of the kinetic energy is lost as heat.Let's say you have a turbojet and a turbofan that produce equal thrust. The energy needed to get the smaller mass of air going faster (turbojet) is greater than the energy needed to increase the speed of the larger mass of air (turbofan).

Think of it this way. Momentum is mass times velocity. Kinetic energy is 1/2 mass times velocity squared. So kinetic energy is 1/2 momentum times velocity. For the same momentum (the same thrust) your energy goes up in proportion to velocity. You are wasting more energy (and more fuel) just using a jet engine. Of course, there are trade-offs. The jet engine is simpler and cheaper and smaller for the same thrust. But it uses more fuel to produce the same amount of thrust.

This is why no modern full size aircraft relies on turbojets, because they're terribly inefficient compared to turbofans and produce much less thrust per unit of fuel.

Don’t forget, turboprops are literally jet engines at their core, blowing their exhaust across a wheel connected to a gear box, then the prop…or that every jet engine on every airliner built since the 80’s is a literally a jet core blowing its exhaust across a wheel connected to a big fan. So….there’s that.

Just a guess, but I think this will have primarily commercial applications (drones etc) vs any profitable market on the hobby end? The reason I say that is because the extra weight, diameter, complexity, cost etc are an excellent tradeoff in terms of fuel efficiency gains for longer flights where the monetary and weight savings become more significant? I hope that my guess is wrong though, because this concept is wayyyyy cool.

I just know that the A-10 fans must be dreaming of getting their hands on these motors!

The core engine runs at the same rpm like the normal KJ66. So there were 123.000 rpm at N2 and ~12.500 rpm at N1.

Regards

Pascal

Hello everyone, we have been working on a lager turbofan with thrust class 1 to 1.5kN for a few years now.
I recently uploaded a video, but I can´t post the YouTube link or any pictures.

I think it's because I'm still fairly new here.:)

Regards

Pascal