Engineering Explained
Published on 11 Feb 2018Why Does The Porsche 911 Carrera Put The Engine In The Back?
When you’re sitting at the drawing board, one of the most critical decisions you’ll make in designing a vehicle is where you place the engine. The engine’s placement will have a huge impact on passenger space, practicality, acceleration, braking, weight distribution, and overall driving dynamics.
Porsche decided to put the 911’s engine in the back, behind the rear axle, way back in the day when the 911 was first designed. Since then, that engine has remained there, and while some might say it’s out of stubbornness, there are legitimately wonderful reasons for having a rear-engine car. In this video, we’ll discuss five different scenarios, and how a rear engine makes a lot of sense for each.
March 4, 2018
Why Is The Porsche 911 Rear-Engine?
February 9, 2018
Horsepower vs Torque – A Simple Explanation
Engineering Explained
Published on Jan 17, 2018What’s The Difference Between Horsepower & Torque?
Why Is Peak Acceleration At Peak Power? https://youtu.be/cb6rIZfCuHIWhich is better, horsepower or torque? Two words that are often stated in the car community, but often misunderstood. This video seeks to clarify the difference between the two, without silly analogies like “horsepower is how fast you hit the wall, torque is how far you take it with you” (which, by the way, is highly inaccurate).
Torque is a force acting at a radius, while horsepower simply incorporates time into the equation. This video will discuss the differences, how each applies to internal combustion engines, how they relate, what peak torque and peak horsepower actually mean, and how to analyze torque and horsepower curves. Finally, what’s more important for acceleration, a car with lots of power, or lots of torque?
Let’s get technical. With the context of an engine: Power = Torque x Angular Velocity. In imperial units, this translates to Horsepower = Torque x RPM / 5252.
Engineering Explained is a participant in the Amazon Influencer Program.
October 23, 2017
The Spitfire’s Fatal Flaw
Real Engineering
Published on 3 Aug 2016
October 3, 2017
Primitive Technology: Mud Bricks
Primitive Technology
Published on 22 Sep 2017(Turn on captions [CC] in the lower right corner for more information while viewing.)
I made a brick mold that makes bricks 25 x 12.5 x 7.5 cm from wood. A log was split and mortise and tenon joints were carved using a stone chisel and sharp rocks. The mold was lashed together with cane to prevent it from coming apart when used.Next, I made a mixture of mud and palm fiber to make the bricks. This was then placed into the mold to be shaped and taken to a drying area. 140 bricks were made.
When dry, the bricks were then assembled into a kiln. 32 roof tiles were then made of mud and fired in the kiln. It only took 3 hours to fire the tiles sufficiently. The mud bricks and tiles were a bit weaker than objects made from my regular clay source because of the silt, sand and gravel content of the soil. Because of this, I will look at refining mud into clay in future projects instead of just using mud.
Interestingly, the kiln got hot enough so that iron oxide containing stones began to melt out of the tiles. This is not metallic iron, but only slag (iron oxide and silica) and the temperature was probably not very high, but only enough to slowly melt or soften the stones when heated for 3 hours.
The kiln performed as well as the monolithic ones I’ve built in the past and has a good volume. It can also be taken down and transported to other areas. But the bricks are very brittle and next time I’d use better clay devoid of sand/silt, and use grog instead of temper made of plant fiber which burns out in firing. The mold works satisfactorily. I aim to make better quality bricks for use in furnaces and buildings in future.
WordPress: https://primitivetechnology.wordpress.com
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September 6, 2017
Grand Trunk Pacific Transcontinental Railway Construction – circa 1910 Documentary – WDTVLIVE42
Published on 26 Mar 2017
The Grand Trunk Pacific Railway was a historical Canadian transcontinental railway running from Winnipeg to the Pacific coast at Prince Rupert, British Columbia. East of Winnipeg the line continued as the National Transcontinental Railway, running across northern Ontario and Quebec, crossing the St. Lawrence River at Quebec City and ending at Moncton, New Brunswick. The entire line was managed and operated by Grand Trunk Railway. Construction of this transcontinental railway began in 1905 and was completed by 1913.
Scenes show earthworks and removal of spoil via railway carriages, steam locomotives hauling flatcars, sleepers being unloaded from trains and position on the new roadbed, unloading of rails, fastening of rails to sleepers, and the works train travelling over the newly completed trackwork.
WDTVLIVE42 – Transport, technology, and general interest movies from the past – newsreels, documentaries & publicity films from my archives.
#trains #locomotive #railways #wdtvlive42
September 5, 2017
The 100 Year Flood Is Not What You Think It Is (Maybe)
Published on 6 Mar 2016
Today on Practical Engineering we’re talking about hydrology, and I took a little walk through my neighborhood to show you some infrastructure you may have never noticed before.
Almost everyone agrees that flooding is bad. Most years it’s the number one natural disaster in the US by dollars of damage. So being able to characterize flood risks is a crucial job of civil engineers. Engineering hydrology has equal parts statistics and understanding how society treats risks. Water is incredibly important to us, and it shapes almost every facet of our lives, but it’s almost never in the right place at the right time. Sometimes there’s not enough, like in a drought or just an arid region, but we also need to be prepared for the times when there’s too much water, a flood. Rainfall and streamflow have tremendous variability and it’s the engineer’s job to characterize that so that we can make rational and intelligent decisions about how we develop the world around us. Thanks for watching!
FEMA Floodplain Maps: https://msc.fema.gov/portal
USGS Stream Gages: http://maps.waterdata.usgs.gov/mapper
September 3, 2017
Medieval Castles – Elements of Fortifications
Published on 17 Jan 2017
This episode covers the various elements of castle fortification elements like towers, walls, moats, loopholes, gates, gatehouses, portcullises, battlements, hoardings, draw bridges, etc.
Military History Visualized provides a series of short narrative and visual presentations like documentaries based on academic literature or sometimes primary sources. Videos are intended as introduction to military history, but also contain a lot of details for history buffs. Since the aim is to keep the episodes short and comprehensive some details are often cut.
» SOURCES & LINKS «
Kaufmann, J.E; Kaufmann, H.W.: The Medieval Fortress – Castles, Forts, and Walled Cities of the Middle Ages.
Piper, Otto: Burgenkunde. Bauwesen und Geschichte der Burgen.
Toy, Sidney: Castles – Their Construction and History
September 2, 2017
[Medieval] Castles – Functions & Characteristics (1000-1300)
Published on 30 Sep 2016
» SOURCES & LINKS «
France, John: Western Warfare in the Age of the Crusades 1000-1300#
Ohler, Norbert: Krieg & Frieden im Mittelalter
Contamine, Philippe: War in the Middle Ages
Pounds, Norman J. G. Pounds: Medieval Castle in England & Wales: A Political and Social History
http://faculty.goucher.edu/eng240/early_english_currency.htm
http://www.ancientfortresses.org/medieval-occupations.htm
https://www.britannica.com/technology/castle-architecture#ref257454
http://www.castrabritannica.co.uk/texts/text04.html
https://en.wikipedia.org/wiki/Harlech_Castle
August 30, 2017
“Houston is built on what amounts to a massive flood plain”
While nobody expects 50 inches of rain to fall in one storm, Houston is still badly situated to withstand flooding even from lesser weather events due to its location on a flood plain:
Houston is built on what amounts to a massive flood plain, pitted against the tempestuous Gulf of Mexico and routinely hammered by the biggest rainstorms in the nation.
It is a combination of malicious climate and unforgiving geology, along with a deficit of zoning and land-use controls, that scientists and engineers say leaves the nation’s fourth most populous city vulnerable to devastating floods like the one caused this week by Hurricane Harvey.
“Houston is very flat,” said Robert Gilbert, a University of Texas at Austin civil engineer who helped investigate the flooding of New Orleans after Hurricane Katrina. “There is no way for the water to drain out.”
Indeed, the city has less slope than a shower floor.
Harvey poured as much as 374 billion gallons of water within the city limits, exceeding the capacity of rivers, bayous, lakes and reservoirs. Experts said the result was predictable.
The storm was unprecedented, but the city has been deceiving itself for decades about its vulnerability to flooding, said Robert Bea, a member of the National Academy of Engineering and UC Berkeley emeritus civil engineering professor who has studied hurricane risks along the Gulf Coast.
The city’s flood system is supposed to protect the public from a 100-year storm, but Bea calls that “a 100-year lie” because it is based on a rainfall total of 13 inches in 24 hours.
“That has happened more than eight times in the last 27 years,” Bea said. “It is wrong on two counts. It isn’t accurate about the past risk and it doesn’t reflect what will happen in the next 100 years.”
Some of the blame (a lot of the blame) for locating vulnerable properties in flood-prone areas is due to the US government’s flood insurance program:
Texans, watch out. An aftershock is following behind the catastrophic flooding produced by Hurricane Harvey in coastal Texas: The National Flood Insurance Program (NFIP) is coming up for reauthorization.
The main lesson that the public and policymakers ought to learn from Harvey is: Don’t build in flood plains, and especially don’t rebuild in flood plains. Unfortunately, the flood insurance program teaches the exact opposite lesson, selling subsidized insurance whose premiums do not come close to covering the risks home and business owners in flood prone areas face.
As a result, the NFIP is currently $25 billion in debt.
Federally subsidized flood insurance represents a moral hazard, Kevin Starbuck, Assistant City Manager and former Emergency Management Coordinator for the City of Amarillo, argues, because it encourages people to take on more risk because taxpayers bear the cost of those hazards.
Federal Emergency Management Agency data shows that from 1978 through 2015, 3.8 percent of flood insurance policyholders have filed repetitively for losses that account for a disproportionate 35.5 percent of flood loss claims and 30.5 percent of claim payments, Starbuck says. Most of these properties were grandfathered in before the NFIP issued its flood insurance rate maps. The NFIP is not permitted to refuse them insurance or charge them rates based on the actual risks they face.
Clearly, taxpayers should not be required to subsidize people who choose to build and live on flood plains. When Congress reauthorizes the NFIP, it should initiate a phase-in of charging grandfathered properities premiums commensurate with their risks. This will likely lower the market values of affected homes and businesses and thus send a strong signal to others to avoid building and living in such risky areas.
July 18, 2017
Tunnel Warfare During World War 1 I THE GREAT WAR Special
Published on 17 Jul 2017
Check out the WW1 Centennial Podcast: http://bit.ly/WW1CCPodcast
Tunnel and mining warfare was an important part of World War 1, especially on the Western Front and to a lesser, but still deadly, degree on the Italian Front. The dangers for the tunnelers were immense. And the destruction they caused with explosions was too.
July 9, 2017
Why Are I-Beams Shaped Like An I?
Published on 8 Dec 2016
Thank you to my patreon supporters: Adam Flohr, darth patron, Zoltan Gramantik, Josh Levent, Henning Basma, Karl Andersson, Mark Govea
February 14, 2017
Fortress Ottawa, a post-War of 1812 alternative use for Parliament Hill
Colby Cosh linked to this Ottawa Citizen article by Andrew King:
Mapped out with defensive moats, trenches and cannon placements, Bytown’s sprawling stone fortification on the hill was a typical 19th century “star fort,” similar to Fort George in Halifax, also known as Citadel Hill, and the Citadelle de Québec in Quebec City. The “star fort” layout style evolved during the era of gunpowder and cannons and was perfected by Sebastien Le Prestre de Vauban, a French engineer who studied 16th century forts designed by the Knights of Malta. A star fort built by the order with trenches and angled walls withstood a month-long siege by the Ottoman Empire. This layout remained the standard in fort design until the 20th century.
Ottawa’s planned fortress would have also integrated a water-filled moat trench to the south, where Laurier Street is now, to impede an attack. On the northern side, the natural limestone cliffs along the Ottawa River would have served as a defensive measure. Access and resupply points were at the canal near the Sappers Bridge, and a zigzagging trench with six-metre-high stone walls would have run parallel to Queen Street. Parliament Hill, with its gently sloping banks to the south, was called a “glacis” positioned in front of the main trench so that the walls were almost totally hidden from horizontal artillery attack, preventing point-blank enemy fire.
Conceptual image by Andrew King of the “alternate reality” where Fortress Ottawa came to be.
After the rebellions were quashed and the threat of an attack from the United States fizzled out by the mid-1850s, Canada abandoned plans to fortify Bytown.
In 1856, the Rideau Canal system was relinquished to civilian control, and three years later Bytown was selected as the capital of the Province of Canada. The grand plans for Ottawa’s massive stone fortress were shelved and the area that would have been Citadel Hill became the scene of a different kind of battle, that of politics.
November 13, 2016
QotD: Don’t call it software engineering
The #gotofail episode will become a text book example of not just poor attention to detail, but moreover, the importance of disciplined logic, rigor, elegance, and fundamental coding theory.
A still deeper lesson in all this is the fragility of software. Prof Arie van Deursen nicely describes the iOS7 routine as “brittle”. I want to suggest that all software is tragically fragile. It takes just one line of silly code to bring security to its knees. The sheer non-linearity of software — the ability for one line of software anywhere in a hundred million lines to have unbounded impact on the rest of the system — is what separates development from conventional engineering practice. Software doesn’t obey the laws of physics. No non-trivial software can ever be fully tested, and we have gone too far for the software we live with to be comprehensively proof read. We have yet to build the sorts of software tools and best practice and habits that would merit the title “engineering”.
I’d like to close with a philosophical musing that might have appealed to my old mentors at Telectronics. Post-modernists today can rejoice that the real world has come to pivot precariously on pure text. It is weird and wonderful that technicians are arguing about the layout of source code — as if they are poetry critics.
We have come to depend daily on great obscure texts, drafted not by people we can truthfully call “engineers” but by a largely anarchic community we would be better of calling playwrights.
Stephan Wilson, “gotofail and a defence of purists”, Lockstep, 2014-02-26.
March 18, 2016
Explosives – WW1 Uncut – BBC
Published on 31 Jul 2014
The use of massive bombs and charges by the Royal Engineers was crucial during the war. See slow motion footage of them using explosive devices such as the Bangalore Torpedo today.
November 16, 2015
“Skunk Works” founder Kelly Johnson’s Rules Of Management
Tyler Rogoway recounts the set of formal and informal rules Kelly Johnson used while running the famous “Skunk Works”:
Clarence “Kelly” Johnson is the Babe Ruth of aerospace design. Aircraft programs under Johnson were so cutting edge and historically influential, and his cult of personality and management strategy so effective, that he and Lockheed’s Skunk Works (which he also founded) are forever enshrined in mankind’s technological hall of fame.
[…]
Kelly’s Rules
1. The Skunk Works manager must be delegated near complete control of his program in all aspects. He should report to a division president or higher.
2. Strong but small project offices must be provided both by the military and industry.
3. The number of people having any connection with the project must be restricted in an almost vicious manner. Use a small number of good people (10% to 25% compared to the so-called normal systems).
4. A very simple drawing and drawing release system with great flexibility for making changes must be provided.
5. There must be a minimum number of reports required, but important work must be recorded thoroughly.
6. There must be a monthly cost review covering not only what has been spent and committed but also projected costs to the conclusion of the program.
7. The contractor must be delegated and must assume more than normal responsibility to get good vendor bids for subcontract on the project. Commercial bid procedures are often better than military ones.
8. The inspection system as currently used by the Skunk Works, which has been approved by both the Air Force and Navy, meets the intent of existing military requirements and should be used on new projects. Push more basic inspection responsibility back to subcontractors and vendors. Don’t duplicate so much inspection.
9. The contractor must be delegated the authority to test his final product in flight. He can and must test it in the initial stages. If he doesn’t, he rapidly loses his competency to design other vehicles.
10. The specifications applying to the hardware, including rationale for each point, must be agreed upon well in advance of contracting.
11. Funding a program must be timely so that the contractor doesn’t have to keep running to the bank to support government projects.
12. There must be mutual trust between the military project organization and the contractor, and there must be very close cooperation and liaison on a day-to-day basis. This cuts down misunderstanding and correspondence to an absolute minimum.
13. Access by outsiders to the project and its personnel must be strictly controlled by appropriate security measures.
14. Because only a few people will be used in engineering and most other areas, ways must be provided to reward good performance by pay not based on the number of personnel supervised.
Kelly also had a unofficial 15th, 16th, and 17th rules, which he is known to have stated repeatedly to his subordinates:
15. Never do business with the Navy!
16. No reports longer than 20 pages or meetings with more than 15 people.
17. If it looks ugly, it will fly the same.
It is amazing to think that one man did so much to advance mankind’s aerospace capability. Even his few dead-ends and failures had key technologies that would lead to wins or lessons learned down the road.
H/T to @NavyLookout for the link.
