Ultralight Jets are here

[Kiwi303]

Hmm. looking at the shadows, no blade shadows... You may be right, just a scale ground display model with blades added.

 

I wonder if it was ready made and waiting in an "April 1st" folder somewhere on his computer?

 

 

[Downunder]

He has quite a number of photoshop pics in various threads showing how full size aircraft would look at scaled ultralight sizes.

 

Not trying to deceive or anything. Just good fun!

 

If you're lucky he may put up that Tempest pic again....

 

 

[pylon500]

He has quite a number of photoshop pics in various threads showing how full size aircraft would look at scaled ultralight sizes.Not trying to deceive or anything. Just good fun!

If you're lucky he may put up that Tempest pic again....

You remember that one?

 

That followed on from an earlier concept;

 

 

Even started some drawings for it;

 

 

Only got a few bits made.....

 

 

Too many projects....

 

 

[Downunder]

You remember that one?

Only cause it's pretty darn close to a Typhoon, and is the Sabre version.

 

Only need to remove the "girly" thin wings and put a "manly" set of thick typhoon wings on it and we're rollin....

 

Oh yeah, that silly fin fillet needs to go too...lol...

 

 

[Blackhawk]

Here's a short video of the UL-39

 

 

 

[Blackhawk]

More photo's of the UL-39

 

https://www.zonerama.com/JaFR1/Album/1293931

 

 

[Oscar]

With just 170 kgs of usable weight, that means that with two standard crew at ( I believe, 77 kgs for the FAA standard?), 26 kgs of fuel load available. A wee bit over 2 hrs range, but with 45 minutes of fuel required to remain at the end of a flight, you're looking at 75 minutes endurance for your flight plan. So, hops between stops of the order of maybe 150 NM...

 

That's actually not unexceptional for the earlier crop of Euros ( as we discovered with the rego debacle several years ago, where some where found to be only effectively single-seaters for much beyond a couple of circuits! - witness the MTOW thread for a classic example). So, for a bit of a toddle around your local site and maybe a 'hamburger run', this thing could be fun, but you'd have to be a patient man to throw on your Maverick suit and helmet, climb aboard with your mate in his Goose outfit and head off to Ausfly at Temora from say Caboolture to buzz the strip...

 

 

[red750]

Don't forget - in some European countries, 150NM is halfway across the country.

 

 

[aj_richo]

If you can put up with the stupid music, the engine is really working on the flyby.. must be close to max rpm.

 

One wonders about the longevity of the engine?

 

 

[fly_tornado]

modern superbike engines are pretty bullet proof. S1000 engines are $2000 from the wreckers if you cook it

 

 

[Blackhawk]

aj_

 

The engine's top rpm is 13,000, it is governed to 10,000 and runs through a 1.5:1 reduction which gives it the cruise rpm of 6,600 rpm. Ducted fans only operate to around 7000 rpm maximum.

 

The screaming noise is the ducted fan not the engine.

 

The team of UL-39 project is not a company but a group of University Undergraduates from the Aeronautical engineering faculty in the Czech Republic who were doing this as part of their thesis for Aeronautical Engineering and as no one has ever really succeeded in building and flying a Ducted Fan Jet (other than the Jet-hawk which was far from successful) until now; then they should be applauded for their hard work over the last 10 years to achieve the holy grail of ducted fan aircraft flight.

 

Lets hope they or someone else develop this for a ready to fly or kit that would be available to anyone around the world.

 

For those complaining about the top speed, well if 120 knots is not faster enough for a 580mm ducted fan pushing a jet weighing 450kg MTOW aircraft; then you should buy yourself a real L-39 and shares in a fuel company to run it.

 

At least with our 544kg rule we could add more fuel and heavier pilots so long as it was approved by the production company for that weight in other countries.

 

 

[aj_richo]

Mmm.. on approach it sounds like hi-pitch fan noise but as it passes by, it changes to a sweeter high revving exhaust noise.. but what do I know, I haven't seen it up front and personal

 

 

[Oscar]

aj_The engine's top rpm is 13,000, it is governed to 10,000 and runs through a 1.5:1 reduction which gives it the cruise rpm of 6,600 rpm. Ducted fans only operate to around 7000 rpm maximum.

 

The screaming noise is the ducted fan not the engine.

 

The team of UL-39 project is not a company but a group of University Undergraduates from the Aeronautical engineering faculty in the Czech Republic who were doing this as part of their thesis for Aeronautical Engineering and as no one has ever really succeeded in building and flying a Ducted Fan Jet (other than the Jet-hawk which was far from successful) until now; then they should be applauded for their hard work over the last 10 years to achieve the holy grail of ducted fan aircraft flight.

 

Lets hope they or someone else develop this for a ready to fly or kit that would be available to anyone around the world.

 

For those complaining about the top speed, well if 120 knots is not faster enough for a 580mm ducted fan pushing a jet weighing 450kg MTOW aircraft; then you should buy yourself a real L-39 and shares in a fuel company to run it.

 

At least with our 544kg rule we could add more fuel and heavier pilots so long as it was approved by the production company for that weight in other countries.

Without wanting to be a kill-joy here - and I DO consider this to be pretty good effort - if there isn't a production company, then it can only ever be a research exercise. IF the plans etc. were made public, it'd be Experimental - and very, very few Experimental builders have access to c/f manufacturing technology. It's a student research project, and those who have worked on it will have learned lots of good stuff. Perhaps, some entrepreneur will pick up the best of them and turn it into a production aircraft - but as it stands, this is a 'what is possible', not a 'what is available' aircraft.

 

If I were a very, very rich aviator, I think I'd like one, as I'd like a Lotus Exige or an Irving Vincent Aussie Flag 1600 motorcycle, for a Saturday afternoon blast. But, I'm not that rich!.

 

 

[pylon500]

All power to the students, and the state, which no doubt put up the cash for materials.

 

But, and there's always a but, two things I noticed;

 

Looking at the way it's flying in the video, and as has been said above, I think it's using all the power it's got, and it's not really zooming around the sky?

 

(This from an aeromodellers perspective)

 

Not sure if it would get off the ground with two people in it...?

 

The other thing I noticed, which may go some way to curing the first observation, is that they are using a multi-blade fan, as you do, but don't appear to have a flow straightener after the fan?

 

A propellor relies on having as much diameter as possible, thereby becoming a wing travelling through the air generating forward lift (or deflecting thrust backward for the non Brunellians') but only creating a minor amount of swirl around the fuselage.

 

A smaller, faster turning fan needs more blades to absorb the power, but in so doing induces a fair amount of swirl down the tail pipe, losing direct velocity and making the tail pipe appear longer.

 

A flow straightener will redirect the flow directly aft, adding to thrust.

 

 

[Blackhawk]

They do have a flow straightener but they must have it in front of the fan?? why I wouldn't have a clue; it should be behind the fan as you know.

 

 

 

[pylon500]

Yes, often an 'inflow' straightener is used to sort out any turbulence generated from the intake to the fan, to give the fan 'clean' air to run in.

 

This is often a problem with pushers, the aeroplane flies in clean air, but the prop gets dirty air, which is noticed as 'noise' from pushers.