Questions tagged [engine]
For general questions related to aircraft engines; use the [jet-engine] or [piston-engine] tag if possible.
347
questions
3
votes
2answers
288 views
Why is TOGA thrust 'never' 100% N1?
The title is voluntarily the opposite of this question: Why isn´t TOGA thrust always 100% N1 or N2?.
I explain to you with an example: I'm looking to the FCOM of an A320 which states that the "...
20
votes
1answer
3k views
How much weight does a blisk save?
A Blisk is a bladed-disk, all one monocoque component.
So the blades do not have to be inserted and secured, and they are not removable. No nuts and bolts either.
The downside is that any serious ...
1
vote
1answer
62 views
Is there a limit to a subsonic ramjet's pressure ratio?
Subsonic ramjets have high specific fuel consumption. This indicates to me they must have a low pressure ratio.
Is there a limit to how high pressure ratio one can achieve with subsonic air? Why can't ...
1
vote
1answer
95 views
Engine options for aircraft
I have no relationship with aviation except for fascination and experience of flying as passenger.
I was trying to understand engine options available for various planes. Based on my research - ...
1
vote
3answers
117 views
Is there a way for the helicopter rotor to get its power half by wind, half by engine?
Imagine a gyroplane, if something happen mid-flight (when the plane is basically an autogyro and the engine provides no power to the helicopter rotor) and just the wind generated by forward flight can ...
1
vote
2answers
188 views
Why is the fuel:air ratio of a turbojet engine not around ~1:15 (the stoichiometric ratio)? [closed]
Also, what is the maximum fuel:air ratio possible in a combustion chamber of a jet engine?
3
votes
2answers
190 views
Has there ever been a centrifugal turbine in an aircraft engine?
These days, most jet engines feature axial compressors and turbines. However, there are some older aircraft engines with centrifugal compressors, like the Rolls Royce Nene. But I've never heard of any ...
50
votes
2answers
9k views
Should the helicopter be washed after any sea mission?
I was seeing this image:
The caption of this image says (source):
Here a Belgian NH90 NFH returning after a flight over sea. The
helicopter is washed by the fire brigade to remove the salt water...
...
3
votes
0answers
69 views
How does the maintenance cost of turboprops compare to turbofans?
I was initially under the impression that the added complexity of gearing in a turboprop would lead to more maintenance. Then I found out geared turbofans are becoming fairly common so there should be ...
1
vote
1answer
96 views
Why do we lean the mixture in a turbocharged airplane (C182T)?
An increase in Altitude will result in a decrease of atmospheric pressure -1 in. Hg. / 1000ft (ISA conditions), but with a turbocharged airplane it will keep the pressure constant (+/- MSL pressure) ...
0
votes
0answers
36 views
Is there a good way to find out or estimate the prices of certain engines?
I'm specifically looking for the price of a PW150 (5070bhp, Turboprop) and some 55kN Turbofan engine. I'm doing some Direct Operating Cost analysis but I have no idea how much these components should ...
-1
votes
2answers
127 views
What is the physical difference between an airplane having let's say 150 horsepower to an airplane having 250 horsepower?
I was wondering what defines horsepower in an airplane piston engine and how can it be changed?, is horsepower changing during flight?
1
vote
0answers
85 views
What happens if you put too much oil into a reciprocating engine wet sump?
Apparently putting too much oil into your airplane engine is really bad and can be expensive but why? Will the excess oil go out via the oil breather,... ? Thank you
0
votes
0answers
33 views
Relationship of propeller RPM, blade pitch, and drag at very low blade pitch angles
I'm researching the 2016 crash of a PIA ATR-42 in Pakistan, the report on which was recently released. Link to the report: https://www.caapakistan.com.pk/Upload/SIBReports/AAIB-386.pdf
During the ...
0
votes
1answer
75 views
How to find capture area of an engine inlet?
I tried to relate intake pressure recovery in terms which do not involve efficiency of an inlet and capture area, i was able to formulate pressure recovery without intake efficiency but now i need to ...
18
votes
2answers
5k views
Why do new engines have a case with a triangular tiling pattern?
Take a look at the case of new engines such as the F-135:
or the F-119:
Why do they have a case with a triangular tiling pattern? Is this a new technology? A new material?
3
votes
2answers
107 views
What is the relationship between fuel mixture, throttle setting and engine temperature?
I'm trying to understand the relationship between mixture, throttle, and engine temp. In this article from AOPA, it states
... a lean mixture of 16 to 1 is not going to burn as hot as a rich mixture ...
-7
votes
1answer
196 views
What is the reason for different number of front nozzles on commercial aircraft? [duplicate]
As we observe in commercial aircraft, that there are four or two front end nozzles for gas emission in the air.
What is the reason for this variable of 4 or 2 nozzles?
Why is it not a constant?
0
votes
1answer
99 views
Is it possible to build an ultralight helicopter with electric motors as its main engines? [closed]
So I'm trying to make an electric ultralight helicopter, but I'm not sure if it will work. Is it possible to use electric motors to make it fly? If yes, I'm going to need some advice.
I'm expecting ...
2
votes
1answer
177 views
Can aircraft ferry engines for other types of aircraft?
There have been a number of questions that highlighted the fact that the 747 could ferry an engine on an underwing pod.
Was the 747 only capable of ferrying 747 engines? Or was it possible to ferry ...
12
votes
5answers
4k views
Why do aircraft of the same model get progressively larger engines as they mature?
For example, the Cessna 172 started production with the Continental O-300 145hp engine but today sells with the IO-360. Granted that engine is more "modern" but 145hp with the O-300 still ...
0
votes
2answers
148 views
What´s the logic behind the Power Curve?
Aircaft thrust is what counteracts drag, but in flight school they tought us that propeller aircraft are "power producers" and not thrust producers as jets. (That´s because the propeller ...
4
votes
1answer
186 views
What are the reasons for this radial piston engine shut down procedure?
In a radial piston engine, before the engine is shut down the rpm is brought to a considerable high power setting of approximately 1950 rpm. This is to burn the unburnt carbon in the spark plugs. Are ...
1
vote
0answers
80 views
Does the order in which engines in commercial airliners are turned on matter? [duplicate]
I've seen videos on youtube where the pilots always turn on engines 4 and 3 (in a B747-4) first and then turn 2 and 1 on after pushback. Is there a reason behind this, and does the same reason apply ...
3
votes
2answers
186 views
I calculated that Flyer I and II (1903-04) of the Wright brothers were underpowered. Are there better (drag, lift) coefficients than those of Culick?
Based on what the Wright brothers said in a few letters and two article (all relevant excerpts have been attached to this post), and also using the experimental data in the study "AERODYNAMICS, ...
2
votes
1answer
155 views
Why is thrust said to be constant over speed for a jet engine?
I'm just interested in some basic facts regarding flight. On reading the rather "low level" book "Understanding Flight, David F. Anderson, Scott Eberhardt), I recently came up to the ...
3
votes
1answer
359 views
Why do some Turbofan engines have multi-stage fans?
I was wondering why some turbofan engine have multi-stage fans.
e.g. F-119 engine:
F100
Saturn AL-31
6
votes
1answer
3k views
Can you identify this engine?
I am studying Aircraft mechanics currently, and in our academy we have some aircraft engines and different types of them, and I need please your help to know the reference of one of them, and if it is ...
1
vote
2answers
125 views
What modifications need to be made on an engine that normally uses AVGAS to utilize it with MOGAS? [duplicate]
Asking just out of curiosity. What modifications need to be made on an engine, e.g. Lycoming O-360, that normally uses AVGAS to utilize it with MOGAS?
7
votes
7answers
3k views
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?
15
votes
4answers
4k views
Why hasn’t the Wankel rotary engine seen more use in aircraft?
The Wankel rotary engine seems to have several advantages over traditional reciprocating cylinder-and-piston designs. In general, they have a much higher power-to-weight ratio, less vibration, and ...
2
votes
0answers
114 views
How hot is the outer casing of a turbofan engine?
I am able to find temperatures inside different components of turbofan engines, but I can't seem to find what would be the temperature of the external casing/shell of the engine. For example, ...
0
votes
0answers
78 views
Airbus A321 CFM56 Engine - Engine Anti-Ice Valve
For Airbus A321 - CFM56 engine, is there any maintenance task or trouble shooting procedure that require to removal Engine Anti-Ice valve and its hose? (except remove engine and remove the valve ...
4
votes
3answers
624 views
How to Start a Jet Engine [duplicate]
I know how the basics of how jet engines work. I know that air goes into the compressor as the first step of the journey. However, where does the air come from that goes into the jet engine at such ...
1
vote
3answers
168 views
Why would the propeller of a lightsport plane or ultralight w/ Rotax engine be connected to the engine through a clutch, and not turn at low rpm?
Why would the propeller of an ultralight or lightsport plane be connected to the engine through a clutch, and not turn at low rpm?
I've often witnessed the engine start of a Bailey-Moyes Dragonfly (...
2
votes
1answer
126 views
How hot is supersonic intake air?
How hot is the air at the compressor inlet at supersonic speed? For instance the Concorde at mach 2.2 or other jet engines at even higher speeds.
0
votes
2answers
848 views
How to compute thrust to weight ratio of a Cessna 172?
Cessna 172 has weight about 1 ton and it's engine produces about 213 Kg of thrust, and it flies great.
So if I make a plane with a weight of 100kg including pilot and fuel so will 15 kg thrust good ...
0
votes
1answer
134 views
Calculating thrust and required propeller size for a given engine power
I am looking to build an Airplane, the weight of Airplane will be around 20 to 25 kg and I am going to use a 70cc motorcycle engine as an Airplane engine.
I want to know how I can calculate the ...
0
votes
0answers
29 views
Typical burner/combustor dimensions of a jet engine
I know that sounds very generic but lets say for a common engine of a passenger airplane. What could be the typical dimensions for the burner part. I can't find anything online.
Thanks.
0
votes
3answers
424 views
Which is more efficient: a jet engine or a rocket-powered engine?
Knowing that rocket powered engines have higher speeds than jet engines, it raises the question: are jet engines more efficient than rocket powered engines?
This is of course in terms of fuel ...
1
vote
1answer
34 views
Considering a piston engined aircraft, what resistance pressure would be generated within its engine bay against its cooling intake?
Consider a piston engine with all its coolers and components within an aircraft engine bay. To cool this engine, cooling intakes are positioned facing the direction of flight. Now, the condition at ...
8
votes
1answer
2k views
How did War Emergency Power work?
Someone can explain how WEP (War Emergency Power) worked on the planes of the Second World War? And if it was really effective during a combat?
2
votes
1answer
106 views
Does a lean mixture result in a higher cylinder temperature for a given power setting?
From what I know over rich mixture help cools the engine due to evaporation process and lean mixture do the opposite.
So why this graph showing when reaching around peak EGT the opposite happens:
21
votes
1answer
5k views
What's wrong in this engine test cell picture from the book 'Ignition'?
This is picture taken from 'Ignition' book by John D Clarke.
I am bewildered after seeing picture that I can't find wrong in this picture. I guess this is related to the structure of mach ...
5
votes
1answer
183 views
What is ATR Automatic Thrust Restoration in MD-83?
What is ATR Automatic Thrust Restoration in MD-83 ?
2
votes
1answer
2k views
Manifold pressure vs power vs rpm
From what I know MAP is a way of measuring engine power with variable pitch propeller. Greater throttle setting - greater power - greater MAP on the gauge. It happens because MAP is in fact vacum ...
1
vote
2answers
541 views
Does an engine that combines an air-breathing rocket and non-air-breathing rocket exist?
Does a rocket engine that combines air-breathing and non-air-breathing modes exist?
The advantage would be it would have to carry a smaller tank and less oxygen, leaving more room for payload on a ...
3
votes
1answer
2k views
What are the CONT and FLT modes of the 737 start switches?
I pilot the PMDG 737 in my simulator and I know that before takeoff and before landing, the start switches must be set to CONT mode and at high altitudes in FLT mode. But what exactly are CONT and FLT ...
4
votes
5answers
388 views
Can you fly 2000 miles on an engine that costs less than $500k? If so, what type of engine?
Ok so Im exploring ways to bring cargo and medical supplies to various rural cities in say Africa without relying on ground infrastructure. Just short and cheap runways spread around the continent. It ...
-5
votes
2answers
254 views
Is a 3 horsepower engine powerful enough for a 100 pound ultralight? [duplicate]
I'm building an ultralight and it weighs 100 pounds empty. My only engine is 3HP. Is that good enough?
