Questions tagged [engine-design]
Questions about the process and principles used when designing aircraft engines. Use "jet-engine" and "piston-engine" tags to specify a certain type of engine.
245
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Exhaust temperature of CFM56 engines range (Nozzle downstream temp)?
EGT is available but not the temp of the exhaust nozzle in the CFM56 series.
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How big would a single propeller need to be on a 737?
If you wanted a 737 to have the same design as a single prop light aircraft (i.e. just one prop on the nose, no turbines, APUs or other engines) - how big (and how fast) would the propeller have to be ...
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Can you augment turbofan thrust using steam injected into the bypass?
Would using waste heat from the core exhaust to turn water into steam increase takeoff thrust when injected into the bypass before/aft of the fan?
If so, which would be better?
Could this possibly ...
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Humidity and its effect
We know that humidity degrades engine performance. Is there any charts or tables which quantify effect on engine performance due humidity?
The question is specific to helicopters.
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Why aren't ducted rotors used in gas turbines?
I am wondering why (for what I know) no gas turbine employs ducted enclosures for blade arrays on rotor stages.
I tried to search the internet for resources but I couldn't find anything related (so I'...
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How would the shock-ramjet engine work?
I discovered a new theoretical engine called the shock-ramjet (schramjet) and I was wondering, how would it work exactly? I've read that its a high-speed engine that could be used around Mach 10, but ...
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158
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Turbofan engine fan blade leading edge fairing?
A lot of aircrafts feature a leading edge fairing for the wing, at the connection with fuselage, in order to reduce the airflow interference.
Aerodynamically speaking, those fan blades in the turbofan ...
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Would the combustion chambers of a turbine engine generate any thrust by itself? [duplicate]
Well, I know that the combustion chambers drive the compressors, and the reaction occurs, and all that stuff.
But let's imagine that somehow someone is converting a turbine engine (turbojet, turboprop,...
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Do we use static pressure in thermodynamic cycles like brayton instead of total pressure?
I observed that pressure plotted in the graph above increases from 0 to 1.
0 is inlet entrance and 0' (not shown in the graph) somewhere between 0 and 1 is compressor entrance.
Now, we know that at ...
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Where exactly is the engine compartment, remarked in yellow?
Where exactly is the engine compartment, remarked in yellow? We know that normally the air going to the engine passes through the air filter. But when we open the alternate air valve, where does the ...
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What is the purpose of variable stator vanes in the power turbine part of a free shaft gas turbine?
both M1 Abrams tank and T-80 tanks have free shaft gas turbine engines and both of their engines have variable stator vanes in their power turbine part. It says in the picture below that these ...
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The F104 tail pipe is not parallel to the runaway when the aircraft taxi.What is the reason?
The tail section is upward for clearance or to vector up the engine exhaust that will help to rise the nose when the aircraft take-off?
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Why should the dust protection on the Mi-17 helicopter not be used above 3000m?
The Russian Mil Mi-17 helicopters have a dust protection device fitted at engine intake (see the rounded part in front of the intake):
Its checklist gives an altitude limitation from sea level to ...
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aerodynamic forces on an engine cowling
In Mendenhall's book about the Gee Bee racers, he describes that on the Models Z, R-1, and R-2, there was a strong tendency for the engine cowl to get pulled forward and into the prop during races, ...
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Was there any attempt on making a turbofan for mach 1-2 with a "decelerator" air intake?
What made me ask this question is the SR-71 hybrid engines and the efficiency difference between certain engines.
Here is an article from wikipedia showing the efficiency of the engines accordingly to ...
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If they really wanted to, COULD they make a 100% fail-safe airplane? [closed]
With literally every single electronics device that I have bought in the last X years breaking very quickly or immediately, and being of horrible quality, this thought keep popping up in my mind:
If ...
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RR Ultrafan: Why the dramatic change of fan blade design?
The Rolls Royce Ultrafan prototype has been in development for a few years and has usually been seen in the media with very distinctive curved leading edge design as such:
However, this week (...
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Why do modern turbofans have swept blades?
(Picture sources: CF6 and GE90)
Aircraft have swept wings for two reasons:
It reduces the thickness-to-chord ratio of the effective chord, which is ideal for flight at higher Mach numbers.
At ...
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How did the propellers on the B-29 stop perfectly in sync?
In the photos below, the propellers on the B-29 props all stop in the same position. Is this done by hand, it is this automatic?
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Why is the inlet cone on some subsonic engines conical (sharp)?
An inlet cone, as far as I know, is a component on an engine to guide the intake air smoothly into the compressor stage of a jet turbofan engine, it performs as a fairing(aerodynamic covering)of the ...
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Why isn't Yamaha EPeX300Ti more popular in aviation?
The answer to this question might be obvious to experienced aviators. But as an armchair enthusiast, I really couldn't find a satisfactory answer anywhere on the internet.
Below two pages came from ...
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How to compute the mass flow rate for a turboprop at cruise given the static sea level value?
I am trying to obtain the mass flow rate of the Allison T56-A-15 used on the C130H at cruising altitude (so as to solve the Joule-Brayton cycle at cruising altitude). I know from "Turboshaft, ...
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How to determine engine CG in order to calculate moments acting on it?
The aircraft has four engines mounted in pods under the wing. I know the values for the location of engine nacelle front face from the fuselage nose (longitudinal) and distance between engine ...
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Propulsion/ power plant
Let’s say I require 100Hp as stated by my calculations of Thrust for an aircraft-
When finding a power plant for this, would it be better to use a power plant with more Hp or exactly that 100Hp please?...
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Why is China still heavily reliant on Russian turbofan engines?
According to Paul Schwartz, China is "still heavily reliant" on Russian turbofan engines:
Beijing is still heavily reliant on Russian aircraft engines, however, due to the great difficulty ...
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Why do some jet engines have fewer fan blades than others?
I have found out upon researching jet engine fan blades that they can vary from 16 to 34. Why do they vary, I mean, does decreasing or increasing the number of fan blades have any performance impact? ...
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If I put two ductfans behind one another, would I got the sum of the rated thrust or other thrust values?
I am trying to design a VTOL system for a drone and I don't want to have extending motor arms that make it look like a quadcopter. I want to use duct fans and thrust vectoring nozzles. However, the ...
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Would blade-less (Dyson style) jet engines work? [duplicate]
Is it possible to design an aircraft with blade-less (same concept as Dyson) design to generate thrust?
What are some of the key benefits, drawbacks and examples of attempts (if any) at this kind of ...
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Is this concept of a hybrid between a Turbine Engine and a Reaction Engine (Rocket) practical? [duplicate]
So, I don't understand much about engineering in general, but since this is a discussion forum, I like to think that this is just a thought exercise (because it is probably useless).
So, the idea ...
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Are there Hybrid Electric-Combustion Turbine Engines where only the compressor is electric driven?
So, from what I could understand about conventional Turbine Engines and its various types is that normally the combustion chamber ignites fuel with compressed air, rotating a low pressure fan which ...
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Would this concept of Autogyro/Gyroplane be efficient or practical?
First, i'm quite ignorant on aerospace engineering, so I hope I don't make too many incorrect assumptions.
If you don't know what an Autogyro/Gyroplane is, here is the Wikipedia article of it.
The ...
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What are the advantages and disadvantages of fluidic thrust vectoring on aircraft?
The Rockwell XFV-12 was a research project for combining supersonic speed with Vertical Take-Off and Landing, From wikipedia:
The XFV-12 used a thrust augmented wing concept... in which exhaust would ...
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Could small ramjets on the tip of propellers allow for supersonic spin of turbine blades?
Well, of course, if it was practical, someone would've already done that, but I'm still curious.
As you can imagine, I'm an illiterate on the matter of aerodynamics, and even though supersonic ...
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Thrust varaition of a Turbofan engine with altitude and mach number [duplicate]
my classmates and I are trying to find a mathematical model for a low bypass turbofan engine, we ended up finding a model given by Snorri on "General Aviation Aircraft Design", but the ...
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What are the design principles that result in thin, long-span, narrow chord main rotor blades?
Regardless of the overall design configuration of a helicopter, it appears that helicopters have main rotor blades that all fall into the class of ultrahigh aspect-ratio wing design: that is, you ...
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Airflow through axial flow compressor
So I'm reading the Gas Turbine Engine Fundamental, and suddenly come across the airflow passes through one axial compressor stage. I wonder why the Resultant Rotor Inlet Velocity is pointing downward,...
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Is this image of Compressor aerodynamics correct?
Image Source: Air Gas Turbine Technology by Treager, Chapter 5
The rotation direction of rotor shown seems opposite. If it is correct, these are the questions I would like to ask:
Why the Y vector is ...
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How to determine the length of the CD nozzle?
I am designing a convergent nozzle as well as a CD(Converging-Diverging) nozzle. How do I find out the length of those nozzles? If the throat of the CD nozzle has 0 length then what should be the the ...
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What kind of signal is outputted from engine fire sensors
Engine fire sensor informs the pilot engine fire and triggers fire extinguisher to release their payload. However, fire extinguisher valves are controlled through pressure operated switches or ...
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Why pressure and temperature decreases along the length of a convergent nozzle?
I know that the pressure and temperature follows stagnation relations of pressure and temperature as well as area mach relation inside a convergent nozzle along the length. And according to that ...
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What is a ram recovery point?
As aircraft speed increases, thrust tends to decrease somewhat; as the aircraft speed reaches a certain point, ram recovery compensates for the losses caused by the increases in speed. The inlet must ...
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How much extinguishing agent is needed for an engine fire?
I am quite interested in the firefighting fluid tank choices in turbofan-equipped aircraft. As seen in this picture:
Although this is only the APU, but the fire extinguishing agent bottle looks quite ...
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Why are there motive flows for the turbine pumps of Williams International FJ44-3A engine?
For my university project, I am designing the fuel supply of an aircraft using a Williams International FJ44-3A engine.
Studying the related FAA TCDS, I read "Fuel from the motive flow port on ...
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What is the maximum Mach number that can be achieved at the exit of CD nozzle?
I understand that you can get Mach 1 at the throat of a convergent-divergent (CD) nozzle and after that you can have two roots, one is for subsonic and other is for supersonic.
Considering the ...
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How do jet engines cool the gas in the combustion zone?
The adiabatic flame temperature of kerosene in air is 2093 C (source). Modern jet engines have a turbine inlet temperature (TIT) of 1700 to 1800 C. This is the max acceptable temperature before the ...
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Engine Bearings Damage in Radial Engines
Studying the P47's dive performance in DCS, I noticed how it's easy to damage the engine bearings if you windmill the prop at high speed.
Doing some research, I discovered that all radial engines are ...
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Why aren't air turborockets used in military fighters?
Why aren't air turborocket engines used in jet fighters?
Few Third World countries have the capability to manufacture high quality turbine blades. Thus, why not use air turborocket engines for the ...
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Which popular turboprop engine feathers its propeller blades with each shutdown?
Chapter 12 of the FAA Airplane Flying Handbook, discussing multiengine flying, goes into quite a bit of detail in the propeller section about how most feathering-propeller-equipped engines on ...
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Why in a CFM56-3 is vibration measured in displacement for N1 and in velocity for N2?
N1 is measured in mils (thousandth of an inch) and N2 is measured in IPS (inches per second). Why are different methods used?
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BHP increases with Altitude
Searching on internet, I found some performance charts of the Merlin Engine BHP output:
As you can see there is an increase in BHP,(mainting a constant Boost Setting), until reaching the critical ...
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