flying car company in Edmonds, WA

[freebeard]

Let us know what you find out. Thread-jack is OP approved. I've seen a racer-modded Porsche [picture needed].

I thought the original reference was suggesting thrust from the rearward-facing bells.

But I'm reminded of the Moller Supertrapp. It was invented to muffle a snowmobile engine (actually eight snowmobile engines. ) that drove a ducted fan.


http://8903e7f0897f2982f439-51d6683c...ite640x480.jpg

It would lose any additional thrust. Another possibility I saw but can't document was a muffler that was two back-to-back cones in a bellmouth.

[orange4boy]

Some aircraft home builders have done this to help offset cooling drag by entraining with the exhaust. I’m thinking about doing it too. It looks like the exhaust pipe terminating in a Venturi. I like the shape they came up with at Tatra.

[freebeard]

I posted this for aerohead in another thread:

enginehistory.org: Waste Heat Utilization in High Output Aircraft Piston Engines by Robert J. Raymond

3b. Added Thrust

A significant increase in thrust can be realized by the simple expedient of pointing the exhaust stacks toward the rear of the aircraft....
A rule of thumb given by Hoerner [3] is that between 0.11 to 0.13 pounds of thrust per horsepower can be expected from properly directed exhaust stacks with the appropriate exhaust exit area.

[orange4boy]

A rule of thumb given by Hoerner

There goes Hoerner, making rules of thumb great again!

That would be like +25 lbs of thrust at full chooch. I’ll take it.

Did I mention: Love that Tatra!!! The best colour. The best sound!

[seifrob]

Finally got to post answer from VZLÚ (czech aviation research agency and proving lab), where Jetoptera (according to globenewswire.com did some tests.)

I therefore asked at VZLÚ, if Jetoptera really did approach them and did some tests to find out, if people at Jetoptera mean the bussiness or if it is a complete scam as Nikola Motors was and they simply abused a name of some-small-far-east-country-research-lab.

There is an answer I got from their PR dept. (rough translation from czech language done by me), will provide original on demand :-) :

"Project Jetoptera exists, or, rather existed, because investor experiences financial troubles corresponding to covid-19 pandemy and all development is on a halt for now. Jetopteras choice for our research institute was a logical step, because their demonstrator should use H80 series engine from GE Aviation, and that is offspring of our Walter M601. Moreover, GM facility lies just few blocks around.
To the proposed effecincy of the Jetoptera propulsion system we cannot provide any information, because it is not our know-how and we didn´t participate on its development. Our institute was involved only in testing."


.. so, at least we know they really did some tests (though unable to discern, if they bought the testbed and did tests in-house, or paid for certified testing :-( )

[aerohead]

Originally Posted by freebeard

I posted this for aerohead in another thread:

enginehistory.org: Waste Heat Utilization in High Output Aircraft Piston Engines by Robert J. Raymond

He'd know. He was with Messerschmitt during WW-II, and brought over by the O.S.S. under 'Operation Paper Clip.' Like Kamm and Werner von Braun.

[freebeard]

A new episode rehashes how airframe and power plant are separate disciplines in aerospace.

Jetoptera Part 2 : The Evolution of efficient aircraft

What stuck with me was the two contracts from the Air Force for testing and the Fluidic Propulsion System. Their website (jetoptera.com/products/) lists 4 VTOL and 3 STOL models on offer.

[kach22i]

Originally Posted by freebeard

A new episode rehashes how airframe and power plant are separate disciplines in aerospace.

I was just skipping round with the sound off on that video.

At the 9:45 mark on, the attached flow on the curved wing section is physics defying.

Going back to mufflers for a moment, this is the one that currently fascinates me, seen videos of it, how it works, how it sounds on various cars - two of them (one each side) may find themselves on my Porsche if I ever get around to it.

Flowmaster dBX Laminar Flow Muffler
https://fuelinjectorconnection.com/p...-part-12414310

[freebeard]

At the 9:45 mark on, the attached flow on the curved wing section is physics defying.

I find a shot of an airliner, just before the Dyson fan appears. If there were black boxes on the wing top, that would be the FPS.