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Old Jun 17, 2012, 10:00 PM
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Here is what i found in the two threads covering the CS 12bl 70 and 90mm fans for FSA as listed in the threads.

70mm= 4.43 sq/in
90mm= 7.88 sq/in
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Old Jun 17, 2012, 10:25 PM
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f5 has much larger inlets than a t38
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Old Jun 17, 2012, 10:47 PM
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if the fan was located behind the speed brakes on a T-38 the speed brakes could be set up to move up inside the fuse and let aux air to the fan through some naca type ducts in the bottom of the ducting.good inlet ducts would allow good performance at 85% fsa once up to speed.i think this is the best way to have a scale T-38
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Old Jun 17, 2012, 11:39 PM
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Transport would not be a problem as Andy says and I agree. The fuse can be built in two parts, the wings can be removable, the V stab can be removable.

If built for 1 fan, it will have to be 90mm.
70 mm would not have enough juice IMHO
If a 90 mm has 7.88 sq in FSA, we are still short at 72" length.

Operating a fan with less that 100% FSA is choking the fan. The airbrake opening can be used as cheater holes, but that causes thrust loss due to turbulence. Kinda defeats the purpose, IMHO

One idea would be for me to find the size where the intake areas add up to 7.88 sq in. That would be the minimum suitable size for a single 90 mm setup. Stay tuned.
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Old Jun 17, 2012, 11:50 PM
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we've flown planes with 85% fsa and it went 160 mph .there is some ram effect .if cheater is done with naca type scoops threes not that much turbulance.you could cheat the inlet say 10% and it would still look right . i think a 72-75 inch long fuse would be the better market.
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Old Jun 17, 2012, 11:53 PM
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AS knows his airflow. Go with his numbers and you`ll be good.
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Old Jun 18, 2012, 01:03 AM
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Quote:
Originally Posted by awrightbrother View Post
At 144" length the each duct intake area was 12 sq in.

At 72" length, the area goes down by a factor of 4 i.e. it will be 3 sq in.

If we use both ducts to feed one 100 mm fan we have 6 sq in feeding a 9 sq in FSA

It won't work
Fahim
Don't use inlet ducting...

Plenty of planes flown with open ducting and intake lip only, easier for you...

After seeing stock Habu keep up with 120s on circuit during fly in I'm convinced 90% of EDF ducting is bad anyway...
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Last edited by erh7771; Jun 18, 2012 at 01:09 AM.
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Old Jun 18, 2012, 01:08 AM
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dont want to get into a disscussion about ducting .....but i would make plugs and the ducting ,and make them available to those that want ducting.
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Old Jun 18, 2012, 07:51 AM
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Quote:
Originally Posted by AIR SALLY View Post
we've flown planes with 85% fsa and it went 160 mph .there is some ram effect .if cheater is done with naca type scoops threes not that much turbulance.you could cheat the inlet say 10% and it would still look right . i think a 72-75 inch long fuse would be the better market.
I agree. I just don't see modelers jumping all over a 144 inch version. The cost and size would really limit the market. Sure break down would solve the transportation issue but just adds more construction issues.
Mike
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Old Jun 18, 2012, 10:48 AM
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Per inlet!!!!

Quote:
Originally Posted by sam51401 View Post
Here is what i found in the two threads covering the CS 12bl 70 and 90mm fans for FSA as listed in the threads.

70mm= 4.43 sq/in
90mm= 7.88 sq/in
I listed the 70mm fan in that it wouldn't be a single 70 but a twin. This way the inlet for EACH fan would need to be 4.43 sq/in and a AIR SALLY duct to route it to the fan.
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Old Jun 18, 2012, 10:57 AM
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clarify please

Quote:
Originally Posted by awrightbrother View Post
At 144" length the each duct intake area was 12 sq in.

At 72" length, the area goes down by a factor of 4 i.e. it will be 3 sq in.

If we use both ducts to feed one 100 mm fan we have 6 sq in feeding a 9 sq in FSA

It won't work
Fahim
You have "each" duct or intake would be 12 squares, then refine to a 72" model as having only 3 squares. Is this PER SIDE on just one intake???
If so, then at 72", the intakes would be a combined 6 squares total intake area.
If you enlarge by the using a 20% rule then they would be 7.2 sq/in total intake area for the 90mm fan.
IF, IF you then use the the 85% FSA intake for the 90, this would be 6.69
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Old Jun 18, 2012, 12:14 PM
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I got to thinking about it and whatever size you all decide on I really think this is going to be great!!!! There are Tons of F-16's, F18's, Hawks, etc. out there but you just don't see a good quality mid sized T-38/F-5 for EDF.

Getting Air Sally in on it with his high quality duct lay ups and your gona really have something here...

Yep I think you guys got a winner idea here for sure!!

You can put me on the list for one.

Andy
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Old Jun 18, 2012, 12:15 PM
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hmmm, my vote would be for the smaller sized plane, 12 feet long is a very BIG plane. I understand the "knock down" concept but still wouldn't the larger size be that much more expensive than than a 70" ish size? How about the price difference between 1 90mm setup vs 2 70mm systems? Are they similar? But either way I think I'm in!
The T-38 is my favorite jet after the SR-71.

al
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Old Jun 18, 2012, 01:33 PM
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I am all for a 90mm or larger airframe; I love the design and have been following Falcon's build with amazement.

...the big question is what are these expected to cost (estimations)? Knowing the price point would allow me to tell you if I am a buyer or not.
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Old Jun 18, 2012, 02:25 PM
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I think twin 70's is a good idea. The T-38 fuse is wide but not tall/deep. Fitting a single 90mm fan inside will make it quite a bit bigger unless you do a hump like the Top Gun Mig 29 and F-15.

If you want really good performance from a jet, ducting is a must.
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