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experiamental fighter jet style aircraft

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topspeed100

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The Long-EZ, Cozy and similar derivatives carry 21% to 24% of their gross weight on the canard. Their canards are approximately 15% of the main wing area, so the canards have a wing loading that is about 50% higher than the main wing. Depending on the CG location and relative sizes of the main wing and canard, many configurations are possible. As Dana said, if the canard is carrying 50% of the gross weight, you will be in tandem wing territory. The front wing (canard) of Quickie style aircraft carries slightly over 50% of the gross weight.
There is another thread here someone suggest a flying wing with canard elevator control..would it be possible to make 20/80 % carrying canard/wing assebly where the canard is 20% of the total lifting area ?
 

DangerZone

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Has anyone seen this study on ultra light ducted fan design on a scaled version of the L39 albatros http://www.icas.org/icas_archive_cd1998-2010/icas2004/papers/124.pdf
Seems like they have done quite some effort in the design and calculation, the graphics and designs are pretty. Yet there is a bit of a problem, the model would not work as anticipated due to a serious design question.

The first obvious thing is that these 'jet' inlets of the duct would act as an air brake reducing the speed and thrust of the airplane. That is for start, there are other things to consider but this one would make the airplane unflyable in reality.

There is a good reference book about such designs, it was called Ducted Fan Design or something similar. It would be wise for the authors of this airplane to consider all the mistakes possible before building the airplane.
 

topspeed100

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Seems like they have done quite some effort in the design and calculation, the graphics and designs are pretty. Yet there is a bit of a problem, the model would not work as anticipated due to a serious design question.

The first obvious thing is that these 'jet' inlets of the duct would act as an air brake reducing the speed and thrust of the airplane. That is for start, there are other things to consider but this one would make the airplane unflyable in reality.

There is a good reference book about such designs, it was called Ducted Fan Design or something similar. It would be wise for the authors of this airplane to consider all the mistakes possible before building the airplane.
They do acknowledge the duct caused increased drag...and it hardly goes faster than 250 km/h.
 

DangerZone

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They do acknowledge the duct caused increased drag...and it hardly goes faster than 250 km/h.
The way you wrote that implies there is a flyable version of this airplane. Is there one? Because it seems to be something like a project that is intended for paper purposes only, too many loose ends there...

The estimate of 250km/h and the silhouette of the engine like a Hayabusa (around 200HP) would seem like an epic fail. If they would have removed the ducts, shrouds, impellers and the rest of this ducted atrocity such an airplane could easily have reached a cruise speed of around 400km/h with an efficient pair of props on both sides.

If they would manage to cruise at 250km/h in reality on less than 40HP, well, that would be remarkable. A true achievement. And highly optimistic. As in a 'too good to be true' kind of story.
 

Aircar

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It looks like they did a pretty thorough design study to me --they anticipated the engine out and 'blocked' duct case and modified their inlets to avoid the separation issue and adverse effect on handling --what else could they have done (?) -referring to the dismissive posting stating that it is unworkable . This is a "Walter Mitty" sort of concept much like people who build scale P51 Mustangs or the like so it doesn't have to attain some specific performance target or whatever . The L 39 Albatros is a very nice looking aircraft in my opinion (a homebuilt Folland Gnat or Midge at full scale would be a very feasible project using some surplus turbofan along similar lines . The piston engine driven ducted fan is not going to be as efficient as a large free prop but a hell of a lot cheaper and look just as realistic . The RFB Fantrainer was a bit of an orphan -used only by the Thai airforce I think ; the duct was critical and needed a moving slat at the duct leading edge and was very noisy .
 

topspeed100

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The way you wrote that implies there is a flyable version of this airplane. Is there one? Because it seems to be something like a project that is intended for paper purposes only, too many loose ends there...

The estimate of 250km/h and the silhouette of the engine like a Hayabusa (around 200HP) would seem like an epic fail. If they would have removed the ducts, shrouds, impellers and the rest of this ducted atrocity such an airplane could easily have reached a cruise speed of around 400km/h with an efficient pair of props on both sides.

If they would manage to cruise at 250km/h in reality on less than 40HP, well, that would be remarkable. A true achievement. And highly optimistic. As in a 'too good to be true' kind of story.
Sorry I did not read careful enough...I figured it was ducted fan L-39.
 
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