Turbojet engine

The basic idea of the turbojet engine is simple. Air taken in from an opening in the front of the engine is compressed to 3 to 12 times its original pressure in compressor. Fuel is added to the air and burned in a combustion chamber to raise the temperature of the fluid mixture to about 1,100°F to 1,300° F. The resulting hot air is passed through a turbine, which drives the compressor. If the turbine and compressor are efficient, the pressure at the turbine discharge will be nearly twice the atmospheric pressure, and this excess pressure is sent to the nozzle to produce a high-velocity stream of gas which produces a thrust. Substantial increases in thrust can be obtained by employing an afterburner. It is a second combustion chamber positioned after the turbine and before the nozzle. The afterburner increases the temperature of the gas ahead of the nozzle. The result of this increase in temperature is an increase of about 40 percent in thrust at takeoff and a much larger percentage at high speeds once the plane is in the air.

The turbojet engine is a reaction engine. In a reaction engine, expanding gases push hard against the front of the engine. The turbojet sucks in air and compresses or squeezes it. The gases flow through the turbine and make it spin. These gases bounce back and shoot our of the rear of the exhaust, pushing the plane forward

J85 ge 17a turbojet engine

Pioneers

The W.1 turbojet engine used to power the Gloster E28/39 aircraft. It was designed to produce a static thrust of 1,240 lbs at 17,750 rpm. This engine was also the basis of the design of the General Electric I-14 turbojet engine used to power the Bell XP-59A twin engine experimental fighter.

General Electric J85-GE-17A Turbojet

 This turbojet engine was built in 1970 and powered a Cessna A-37 attack aircraft, which was used for ground-support missions during the Vietnam War

Jet engine numbered

  Afterburning Turbojet

 

To move an airplane through the air, thrust is generated by some kind of propulsion system. Most modern fighter aircraft employ an afterburner on either a low bypass turbofan or a turbojet. On this page we will discuss some of the fundamentals of an afterburning turbojet.

In order for fighter planes to fly faster than sound (supersonic), they have to overcome a sharp rise in drag near the speed of sound. A simple way to get the necessary thrust is to add an afterburner to a core turbojet. In a basic turbojet some of the energy of the exhaust from the burner is used to turn the turbine. The afterburner is used to put back some energy by injecting fuel directly into the hot exhaust. In the diagram, you'll notice that the nozzle of the basic turbojet has been extended and there is now a ring of flame holders, colored yellow, in the nozzle. When the afterburner is turned on, additional fuel is injected through the hoops and into the hot exhaust stream of the turbojet. The fuel burns and produces additional thrust, but it doesn't burn as efficiently as it does in the combustion section of the turbojet. You get more thrust, but you burn much more fuel. When the afterburner is turned off, the engine performs like a basic turbojet.

Afterburners are only used on supersonic aircraft like fighter planes and the Concorde supersonic airliner. (The Concorde turns the afterburners off once it gets into cruise. Otherwise, it would run out of fuel before reaching Europe.) Afterburners offer a mechanically simple way to augment thrust and are used on both turbojets and turbofans.

What volcanic ash does to jet engines 

 

We tend to forget as we jet around the world the jet engine technology that propels us – especially as newer planes like the Airbus A380 are so much quieter the engine noise isn’t as noticeable. Jet engines are amazing for their ingenious simplicity, but as engineering experts have been warning today, jet engines are also very delicate and susceptible to damage from dust, sand and ash. That’s the reason behind the grounding of planes all over Europe.
So what does volcanic ash actually do to a jet engine? Dr Rob Howell, Department of Mechanical Engineering at the University of Sheffield explained it to the UK Science Media Centre this way:

Bills Turbojet Engine.

Another pic of the engine prior to teardown.  The pump and motor are coupled together, and are from an old oil burner that i had i cleaned up.  The pump is a single stage 100 psi unit.  The only way to bring the pressure down was to use the bleeder nut to adjust the psi, this seems to work well.  The oil is pumped at around 25-30 psi.  Oil is Mobil1, the oil pump has a built in micro mesh filter and seems to be doing it's job well.  This engine is started with a vacum cleaner. And the procedure is pretty much the same as all the other units that have been built.

Please note these turbos can be extremely dangerous, take precautions to keep
yourself safe as well as the people that are near by.

Pic of new stainless flame tube test.  I was very happy that it started right up.
This was taken at half throttle, and full blower, start air.  My neighbors are now getting used to the sights and sounds coming from my garage.  After some modifications  to the gaskets and a paint job  for the complete engine I will
reassemble the jet.  Next is the design of an oil cooler and  some kind of power turbine setup do drive  a model  plane prop.  This engine is going to the annual car show and should turn a few heads I hope, a lot of people will bring their steam engines, but I'll have a turbojet !

Looking into the hot end, inlet.  That is a  2 1/2" pipe flange on the hot end with a nipple threaded onto it , the combustor then threads onto that .  The whole engine is either bolted or screwed together, I didn't have access to a welder.  This is not a big deal it's easy to pull apart  and  reassemble.  This can be done in about 15 minutes.  The can you see is my oil tank.  Very high tech huh?

This is the fuel nozzle, it can be moved in or out for adjustment, for a better combustion burn.  The Ignition is nothing more than a gas grill igniter, attached to a super long reach spark plug.  The plug is an ignitor that came from an propane heater. This system works well  and I have it set for a 1/4 inch gap.

Original copper flame tube and steel liner.  I replicated the flame tube and it is now stainless steel.  The liner was taken from an old oil burner.

Pic of new stainless flame tube with flame retention head.  This was an exact duplicate of the copper one, and this has been tested and starts fine.  Next to it is the fuel nozzle this was taken from the oil burner and I removed the strainer and fuel swirler that was inside the nozzle.  The nozzle tip was drilled out to 1/16th".
Fuel nozzles  can be changed in a matter of minutes.  I haven't tried any newer type arrangements as of yet.

Hopefully I'll have my own site soon and will have more cool stuff in regards to turbos.  My interest with these units stems back in the 70s when I worked on Hueys in the ARMY.  My favorite engine was the Allison T-55 gas turbine it was a very rugged turbo shaft.