3dthinker
New Member
Joined: March 2014
Posts: 2
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Post by 3dthinker on Feb 28, 2014 23:22:59 GMT -5
Hello all, I had a few questions about turbines and how they work, but have never delt with thm nor understand them really. I am a 3D modeler working on a personal project and was hopeing to get some help on a design I was looking into. I'm creating a 3D model of a jet aircraft that has forward sweeping wings and a single jet engine built into it. Looking into turbines I know that they are designed to suck in air and push it out creating thrust (a very crude explaination of it) I have a design that the jets intake basically acts as two seperate intakes funneling into one exit point for the engine sorta like a Y set up both on either side of the cockpit pulls in the air with two smaller turbines and forces it out through one engine like a funnel. Thats where I wonder if scientifically speaking that makes any sence at all? All the systems I've ever seen have a long tube to push everything through and I'm doubting that with doule intakes that it could go into one engine. I wanted to ask about it at the very least and get ome input on my design with the science behind it. I'm guessing that if i go witht he sorta set up i want i would have to use a system more like an f-16 where it has one large intake that runs the engine. I'll post some pics of the design thus far and see if any of you kind folk have the patients to at least give me a basic understanding of how it would have to be designed to actually function. thank you for your time
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Post by racket on Mar 1, 2014 0:39:47 GMT -5
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3dthinker
New Member
Joined: March 2014
Posts: 2
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Post by 3dthinker on Mar 1, 2014 11:45:16 GMT -5
thanks for the reply and link,
I looked it up and read up a little about it. If i'm understanding it properly basically its one turbine that sits further back in the fusiloge with two different intakes that pull into the single turbine. Nice little supersonic jet for a single engine. I'm guessing the newer jets go fast due to having larger or multiple engines being built into them.
Well as for my designed at least I have a reference on how it would be set up with a single engine like this. The only thing i was wondering about was on the starfighter it had its rear erm... tail wings lifted above the engine near the top of the tail fine. Would that be due to heating issues with the engine and the tail wings being to close to it?
thanks for the imput i'll be redoing parts of my design soon.
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rythmnbls
Veteran Member
Joined: August 2011
Posts: 145
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Post by rythmnbls on Mar 1, 2014 13:45:54 GMT -5
The tail plane is probably mounted where it is to clear any turbulent air generated by the main wings. Turbulence at speed would be a very bad thing and result in authority loss. It was one of the first problems encountered in the early days of supersonic flight.
Regards.
Steve.
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Post by racket on Mar 1, 2014 17:30:18 GMT -5
Hi
Speed was a problem for that aircraft , it was potentially a lot faster due to its shape but the engine limitation due to ram pressure /temperature rise caused engine problems according to the Wiky article...... ..............."Its thrust-to-drag ratio was excellent, allowing a maximum speed well in excess of Mach 2: the top speed of the Starfighter was limited more by the aluminum airframe structure and the temperature limits of the engine compressor than by thrust or drag "
Air gets rather hot at speeds of Mach 2 , friction on the body generates a lot of heat and having to slow air down from > 2,000 ft/sec to ~500 ft/sec for it to enter the engine creates a great pressure rise as well as a large temperature rise in the air entering the compressor ...............the total temperature at Mach 2 at sea level is ~550 deg F - 290 deg C , at 35,000 ft its ~350 F - 175 C ................Mach 2 and above is the realm of Ramjets , and even they start to have "difficulties " above Mach 4.
The Lockhead YF12A ( similar to the SR71) at Mach 3 has fuselage skin temperatures of ~600 F - 315 C at the nose to ~1100 F - 600 C at the tail , ..........with the fuselage growing ~75mm -3 inches in length from expansion .
Cheers John
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