J-20 5th Gen Fighter Thread IV (Closed to posting)

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latenlazy

Brigadier
by78 said:
I browsed the RC model maker's website but couldn't find any info. on the J-20 model.

Interestingly, their F-22 model has a T/W ratio of approximately 1.27, which is kind of close to the actual thing.

Apparently, the fan motors generate under 1kg of thrust, and the body + servos + motor weigh around 740g.
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Found the weight but there's a range between 450-740 g. Not sure where you got the thrust numbers but assuming. Thrust of 1kg that's a 1.35 t:w ratio at the lowest, and 2.22 at the highest. This compares to the F-22's T:W ratio of 1.09 at loaded weight.
 
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by78

by78

General
latenlazy said:
Found the weight but there's a range between 450-740 g. Not sure where you got the thrust numbers but assuming. Thrust of 1kg that's a 1.35 t:w ratio at the lowest, and 2.22 at the highest. This compares to the F-22's T:W ratio of 1.09 at loaded weight.
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For their F-22 model, the motor specs are 2200kv at 30A max, mated to a 6x4 prop. I couldn't find thrust data, so I looked around on the web for a similar setup, and I got just under 1kg in thrust.

From Wikipedia article on thrust-to-weight, I got 1.26 for the F-22 with loaded weight and 50% fuel.
 
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latenlazy

Brigadier
by78 said:
For their F-22 model, the motor specs are 2200kv at 30A max, mated to a 6x4 prop. I couldn't find thrust data, so I looked around on the web for a similar setup, and I got just under 1kg in thrust.

From Wikipedia article on thrust-to-weight, I got 1.26 for the F-22 with loaded weight and 50% fuel.
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I went with 100% fuel. But yeah that's the rough idea.
 
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paintgun

Senior Member
take into account that the power plant of does not always perform at maximum thrust, there is also drag at higher speed

that video is pretty old and it might show how spectacular the capabilities of such an airplane with canards, but given the circumstances it is unlikely to simulate anything of an actual combat aircraft
 
by78

by78

General
latenlazy said:
I went with 100% fuel. But yeah that's the rough idea.
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So I guess the important unknown is this: did the guys at RCpower try to approximate a reasonable T/W ratio with their J-20 model? I know they did with their F-22.

Jeff raised some very good points that the model doesn't begin to approximate weight distributions, stresses, etc. of the real thing. It's therefore not valid to extrapolate the performance of J-20 based on an RC model.

That said, the comparisons made in the videos are between the RC model of J-20 and RC model of F-22, the Eurofighter, the F-18, etc. I believe these comparisons of RC models have more validity, but how much they translate into differences in the performance of their real-life counterparts is another matter.

It's certainly all very interesting.
 
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latenlazy

Brigadier
by78 said:
So I guess the important unknown is this: did the guys at RCpower try to approximate a reasonable T/W ratio with their J-20 model? I know they did with their F-22.

Jeff raised some very good points that the model doesn't begin to approximate weight distributions, stresses, etc. of the real thing. It's therefore not valid to extrapolate the performance of J-20 based on an RC model.

That said, the comparisons made in the videos are between the RC model of J-20 and RC model of F-22, the Eurofighter, the F-18, etc. I believe these comparisons of RC models have more validity, but how much they translate into differences in the performance of their real-life counterparts is another matter.

It's certainly all very interesting.
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Like I said earlier, interesting, but best not to draw too much from it. I think the RC model video gives us some insight into some of the basic aerodynamic principles behind the J-20's design, but it doesn't come close to telling us the whole story.
 
by78

by78

General
A nice comparison photo:

12671817235_7983182b3a_o.jpg


Does any know what those two hexagons (just forward of side weapons bay) are?
 
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