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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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4 answers
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Why the combustion chambers of a turbine engine aren't used to spin the compressor like a firework wheel?

I searched here in this stack and the only question I found was this one, but I feel like it wasn't very well worded and it is also considered a duplicate. If this question is considered a duplicate ...
mandiokai's user avatar
  • 620
2 votes
1 answer
163 views

Is it a good idea to increase exhaust duct length?

I am a big newbie in aviation but still, I have a question: Let's assume a civil aircraft (Boeing 737 or Airbus 320), flying with those impossible real life hypothesis: the exact SAME turbofan are ...
user12642493's user avatar
12 votes
3 answers
6k views

How did the sailor survive getting sucked into an engine?

I'm sure we've all seen the famous video of the Navy sailor getting sucked into an engine. Can someone explain how was this possible? I've read many comments but still don't have a visual idea how ...
Gabe's user avatar
  • 3,269
5 votes
2 answers
1k views

What kind of combustor are these engines using?

I'm familiar with the wikipedia-standard can/can-annular/annular style combustors, but I've found a design that don't seem to fit into any of these categories, used in a number of engines such as the ...
ChipperCorgi's user avatar
1 vote
0 answers
64 views

How to calculate EGT Margin for P&W engines (PW1100g) ? (Theta parameter correction)

My goal is to obtain engine baselines and calculate EGT Margin for Pratt&Whitney PW1100g engines (specifically, PW1133GA-JM) I have a large dataset of engine reports recorded during takeoff. I ...
Bogdan's user avatar
  • 11
2 votes
3 answers
625 views

Why weren't WWII piston aircraft able to fly at 500mph?

So, I just noticed that typical WWII piston engine fighter aircraft had a power to weight ratio of around 300W/kg, even at gross weight and altitude. This means that if we assume that an aircraft has ...
Abdullah is not an Amalekite's user avatar
2 votes
2 answers
172 views

Confusing justification for new engines for Bomber B

https://en.wikipedia.org/wiki/Bomber_B With engines in the 2,000 to 2,500 hp range, twin-engined aircraft would have considerably more surplus power, allowing for much greater payloads. In theory, ...
Abdullah is not an Amalekite's user avatar
0 votes
5 answers
323 views

How/why does engine torque and horsepower affect aircraft speed? [duplicate]

I'm curious as to why torque and horsepower affect an aircraft's speed. AFAIK, it's only the engines RPM that affect speed, right? Does this mean an engine's torque/horsepower only affects the speed ...
aleks lacroix's user avatar
3 votes
2 answers
609 views

What is the general operating temperature of Free Piston Turbine Engines?

The turbine in turbine engines can face temperatures from the combustion chamber up to 1700ºC, but I can't find any information on the operational temperature of free piston turbine engines. I'm ...
Fulano's user avatar
  • 121
0 votes
1 answer
118 views

Coordinate system in aircraft. Question about step between lines

Good day! Can you help me? I doing a restoration of the plane's geometry. I want to do restoration use a theory. But I have not information about step (size) between B.L. (W.L.) lines. As example - ...
Ruslan Pala's user avatar
4 votes
0 answers
129 views

How does the Allison (now Rolls-Royce) CX-31 centrifugal compressor achieve a pressure ratio of 10?

Centrifugal compressors typically have pressure ratios up to around 7 or 8. But Rolls-Royce has a graphic showing the evolution of their line of small turboshaft engines that shows the compressors ...
sf44's user avatar
  • 41
1 vote
1 answer
155 views

Exhaust temperature of CFM56 engines range (Nozzle downstream temp)?

EGT is available but not the temp of the exhaust nozzle in the CFM56 series.
Setare's user avatar
  • 13
6 votes
1 answer
3k views

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 ...
Cloud's user avatar
  • 13.5k
0 votes
1 answer
175 views

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 ...
usernamechecksout's user avatar
0 votes
1 answer
84 views

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.
Vikas Singh's user avatar
0 votes
2 answers
248 views

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'...
temporary_pigeon's user avatar
1 vote
1 answer
133 views

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 ...
Mateo's user avatar
  • 746
2 votes
1 answer
186 views

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 ...
Frank's user avatar
  • 415
5 votes
4 answers
721 views

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,...
Fulano's user avatar
  • 121
8 votes
2 answers
911 views

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 ...
pilot162's user avatar
  • 2,205
1 vote
1 answer
963 views

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 ...
Timothy Scherer's user avatar
0 votes
1 answer
138 views

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?
George Geo's user avatar
  • 2,111
6 votes
1 answer
464 views

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 ...
Vikas Singh's user avatar
4 votes
1 answer
236 views

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, ...
niels nielsen's user avatar
3 votes
1 answer
160 views

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 ...
Fulano's user avatar
  • 121
-7 votes
1 answer
204 views

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 ...
Coron's user avatar
  • 1
4 votes
0 answers
471 views

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 (...
Darkcat Studios's user avatar
6 votes
1 answer
750 views

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 ...
Aditya Sharma's user avatar
24 votes
4 answers
7k views

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?
Boeing787's user avatar
  • 6,454
9 votes
2 answers
1k views

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 ...
Richard M's user avatar
5 votes
0 answers
1k views

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 ...
crow's user avatar
  • 51
1 vote
1 answer
176 views

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, ...
fras's user avatar
  • 11
0 votes
1 answer
276 views

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 ...
itsChibi's user avatar
  • 119
0 votes
2 answers
121 views

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?...
Will's user avatar
  • 9
6 votes
4 answers
1k views

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 ...
Rodrigo de Azevedo's user avatar
4 votes
3 answers
1k views

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? ...
Aviation Enthusiast's user avatar
0 votes
1 answer
344 views

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 ...
Faito Dayo's user avatar
-3 votes
1 answer
16k views

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 ...
TayE's user avatar
  • 6,595
-3 votes
1 answer
132 views

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 ...
mandiokai's user avatar
  • 620
6 votes
7 answers
4k views

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 ...
mandiokai's user avatar
  • 620
0 votes
1 answer
336 views

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 ...
Fulano's user avatar
  • 121
0 votes
1 answer
907 views

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 ...
Fulano's user avatar
  • 121
3 votes
1 answer
319 views

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 ...
Fulano's user avatar
  • 121
4 votes
1 answer
1k views

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 ...
AlejandroArias's user avatar
8 votes
2 answers
430 views

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 ...
niels nielsen's user avatar
4 votes
2 answers
444 views

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,...
John Enrique's user avatar
7 votes
3 answers
2k views

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 ...
Noorul Quamar's user avatar
0 votes
1 answer
769 views

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 ...
Twisampati Roy Chowdhury's user avatar
0 votes
1 answer
97 views

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 ...
Faito Dayo's user avatar
1 vote
0 answers
108 views

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 ...
Twisampati Roy Chowdhury's user avatar

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