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.
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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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Why do new jet engines cost billions to design?
This question might come off as crude because it involves people's salaries, but I do not understand why new designs of large turbofans cost many billions of dollars to design. For example, the Pratt &...
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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 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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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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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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How are the compressor and turbine disks connected?
What is the typical way the compressor and turbine disks connected to (LP/HP) shaft ? How are the disks connected to each other (e.g., curvic coupling, bolts or others ?)
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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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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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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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Why do the Comet's engines point outwards?
As it's visible from the images below,
when looking at the plane from the top, the engines point outwards and they are banana-shaped, why is that?
(unfortunately I couldn't find a real photo ...
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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,...
CommunityBot
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What are those things on the B747 engine pylons?
I noticed some dots and lines on the Boeing 747 engine pylons. What are they?
The above image is as seen in this video at 2:18.
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What is this hole at the front of the engine pylon on a Boeing 707?
Images of the Boeing 707 show a hole at the front of the engine pylon just above the engine.
Can someone please tell me what is the purpose?
Also why do images show the hole absent on the left outer ...
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What is the purpose of the air inlets on an A320neo's pylon (LEAP-1A)?
What is the purpose of the air inlets on an A320neo's pylon (LEAP-1A)? Passive cooling, air bleed like in the 707, or something else?
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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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Why don't bypass ducts in jet engines narrow down the flow to accelerate it?
Since decreasing the flow area increases flow velocity, why don't turbofan bypass ducts narrow down to produce more thrust?
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In high-altitude piston aircraft, what type of forced induction (boost) is used?
In high-altitude piston aircraft, what type of forced induction (boost) is used? Turbocharger or supercharger?
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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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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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Would a ducted fan with a nozzle like a jet engine have more thrust than a normal ducted fan?
I'm trying to design a miniature ducted fan engine for a small project, but I'm not too sure how much contraction should happen between the fan and the end of the engine, if at all.
Engines like this ...
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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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Is there a good online source on rotating detonating pulse engine?
I can't find a clear presentation that would explain the workings of a rotating pulse detonation engine graphically, only useless (to a layman) cfd simulations of the combustion chamber. Please share ...
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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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How is lift transferred from rotor to chassis (or weight, the other way around)?
I am trying to find out how a helicopter rotor's lift is transferred to the chassis. Equivalently, how is the weight of the helicopter transferred to the rotor blades?
While looking for this online, ...
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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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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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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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What is "Boost"/"Super Boost" in the PW127M/N?
This incident describes rejected take-off due to the "boost" being inoperable. The reason for the RTO is obvious: engine power lower than expected.
But what is this ominous "boost" technology?
CommunityBot
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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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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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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? ...
CommunityBot
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Why is there a pressure drop in the combustion section of a jet engine?
This image, referenced in this question, shows in green the pressure value in a jet engine:
The combustion section between compressor and turbine is where fuel is injected, mixed with air, and ...
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Why weren’t large, high-power radial engines built to take advantage of the Meredith effect?
Most aircraft piston engines fall into two general categories:1
Radial engines (radials for short2) have their cylinders radiate out from the crankshaft in a star pattern; they tend to have a blunt, ...
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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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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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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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Why do most radial engines use an odd number of cylinders?
To help suppress vibration, most 'V' and 'horizontal' engines use an even number of cylinders as closely opposed as possible. Radial engines are well known for excessive vibration. For some reason ...
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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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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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