Monthly Archives: August 2015

my electric cart of the future

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Buxbaum and Sperka cart of future

Buxbaum and Sperka show off the (shopping) cart of future, Oak Park parade July 4, 2015.

A Roman chariot did quite well with only 1 horse-power, while the average US car requires 100 horses. Part of the problem is that our cars weigh more than a chariot and go faster, 80 mph vs of 25 mph. But most city applications don’t need all that weight nor all of that speed. 20-25 mph is fine for round-town errands, and should be particularly suited to use by young drivers and seniors.

To show what can be done with a light vehicle that only has to go 20 mph, I made this modified shopping cart, and fitted it with a small, 1 hp motor. I call it the cart-of the future and paraded around with it at our last 4th of July parade. It’s high off the ground for safety, reasonably wide for stability, and has the shopping cart cage and seat-belts for safety. There is also speed control. We went pretty slow in the parade, but here’s a link to a video of the cart zipping down the street at 17.5 mph.

In the 2 months since this picture was taken, I’ve modified the cart to have a chain drive and a rear-wheel differential — helpful for turning. My next modification, if I get to it, will be to switch to hydrogen power via a fuel cell. One of the main products we make is hydrogen generators, and I’m hoping to use the cart to advertise the advantages of hydrogen power.

Robert E. Buxbaum, August 28, 2015. I’m the one in the beige suit.

Racial symbols: OK or racist

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Washington Redskins logo and symbol. Shows race or racism?

Washington Redskins lost protection of their logo and indian symbol. Symbol of race or racism?

In law, one generally strives for uniformity, as in Leviticus 24:22: “You shall have one manner of law; the same for the home-born as for the stranger,”  but there are problems with putting this into effect when dealing with racism. The law seems to allow each individual group to denigrate itself with words that outsiders are not permitted. This is seen regularly in rap songs but also in advertising.

Roughly a year ago, the US Patent office revoked the copyright protection for the Washington Redskin logo and for the team name causing large financial loss to the Redskins organization. The patent office cited this symbol as the most racist-offensive in sports. I suspect this is bad law, in part because it appears non-uniform, and in part because I’m fairly sure it isn’t the most racist-offensive name or symbol. To pick to punish this team seems (to me) an arbitrary, capricious use of power. I’ll assume there are some who are bothered by the name Redskin, but suspect there are others who take pride in the name and symbol. The image is of a strong, healthy individual, as befits a sports team. If some are offended, is his (or her) opinion enough to deprive the team of its merchandise copyright, and to deprive those who approve?

More racist, in my opinion, is the fighting Irishman of Notre Dame. He looks thick-headed, unfit, and not particularly bright: more like a Leprechaun than a human being. As for offensive, he seems to fit a racial stereotype that Irishmen get drunk and get into fights. Yet the US Patent office protects him for the organization, but not the Washington Redskin. Doesn’t the 14th amendment guarantee “equal protection of the laws;” why does Notre Dame get unequal protection?

Notre Damme Fighting Irish. Is this an offensive stereotype.

Notre Dame’s Fighting Irishman is still a protected symbol. Is he a less-offensive, racist stereotype?

Perhaps what protects the Notre Dame Irishman is that he’s a white man, and we worry more about insulting brown people than white ones. But this too seems unequal: a sort of reverse discrimination. And I’m not sure the protection of the 14th was meant to extend to feelings this way. In either case, I note there are many other indian-named sports teams, e.g. the Indians, Braves, and Chiefs, and some of their mascots seem worse: the Cleveland Indians’ mascot, “Chief Wahoo,” for example.

Chief Wahoo, symbol of the Cleveland Indians. Still protected logo --looks more racist than the Redskin to me.

Chief Wahoo, Still protected symbol of the Cleveland Indians –looks more racist than the Redskin to me.

And then there’s the problem of figuring out how racist is too racist. I’m told that Canadians find the words Indian and Eskimo offensive, and have banned these words in all official forms. I imagine some Americans find them racist too, but we have not. To me it seems that an insult-based law must include a clear standard of  how insulting the racist comment has to be. If there is no standard, there should be no law. In the US, there is a hockey team called the Escanaba (Michigan) Eskimos; their name is protected. There is also an ice-cream sandwich called Eskimo Pie — with an Eskimo on the label. Are these protected because there are relatively fewer Eskimos or because eskimos are assumed to be less-easily insulted? All this seems like an arbitrary distinction, and thus a violation of the “equal protection” clause.

And is no weight given if some people take pride in the symbol: should their pride be allowed balance the offense taken by others? Yankee, originally an insulting term for a colonial New Englander became a sign of pride in the American Revolution. Similarly, Knickerbocker was once an insulting term for a Dutch New Yorker; I don’t think there are many Dutch who are still insulted, but if a few are, can we allow the non-insulted to balance them. Then there’s “The Canucks”, an offensive term for Canadian, and the Boston Celtic, a stereotypical Irishman, but also a mark of pride of how far the Irish have come in Boston society. Tar-heel and Hoosiers are regional terms for white trash, but now accepted. There must be some standard of insult here, but I see none.

The Frito Bandito, ambassador of Frito Lays corn chips.

The Frito Bandito, ambassador of Frito Lays corn chips; still protected, but looks racist to me.

Somehow, things seem to get more acceptable, not less if the racial slur is over the top. This is the case, I guess with the Frito Bandito — as insulting a Mexican as I can imagine, actually worse than Chief Wahoo. I’d think that the law should not allow for an arbitrary distinction like this. What sort of normal person objects to the handsome Redskin Indian, but not to Wahoo or the Bandito? And where does Uncle Ben fit in? The symbol of uncle Ben’s rice appears to me as a handsome, older black man dressed as a high-end waiter. This seems respectable, but I can imagine someone seeing an “uncle tom,” or being insulted that a black man is a waiter. Is this enough offense  to upend the company? Upending a company over that would seem to offend all other waiters: is their job so disgusting that no black man can ever be depicted doing it? I’m not a lawyer or a preacher, but it seems to me that promoting the higher levels of respect and civil society is the job of preachers not of the law. I imagine it’s the job of the law to protect contracts, life, and property. As such the law should be clear, uniform and simple. I can imagine the law removing a symbol to prevent a riot, or to maintain intellectual property rights (e.g. keeping the Atlanta Brave from looking too much like the Cleveland Indian). But I’d think to give people wide berth to choose their brand expression. Still, what do I know?

Robert Buxbaum, August 26, 2015. I hold 12 patents, mostly in hydrogen, and have at least one more pending. I hope they are not revoked on the basis that someone is offended. I’ve also blogged a racist joke about Canadians, and about an Italian funeral.

Hill-o-beans. Winning at Bunker Hill lost America for Britain.

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The greatest single victory of the American Revolution in terms of British soldiers killed or wounded was the battle of Bunker Hill. It was won without leaders or strategy, or any real sense of victory: the British held the hill when the battle was over. Still, one can easily echo the comment of General George Clinton: “A few more such victories would have shortly put an end to British dominion in America.” How this came to be is a real lesson in how group-think can lead to the destruction of an army of the finest soldiers on earth by a bunch of untrained rabble.

By May 1775, Boston was a valuable port, British-controlled, but much smaller than it is today. It was a knob-hill peninsula cut off from the rest of the colonies except for one narrow road, called “The Neck,” or The Roxbury Neck to distinguish it from a similar neck road leading to nearby Charlestown peninsula. Following the rumpus battles of Lexington and Concord, Boston was surrounded by 15,000 ill-clad, undisciplined colonials who ate, drank, and shot at stuff in plain view of the 6000 trained soldiers and 4 Generals in Boston. The Neck road was blocked by Continental militia and cannon making it difficult, but not impossible for the British army to leave by that route to demonstrate control of the colonies. The British had sea-power though and could use it to attack anywhere they liked on the American coast. For their attack on Lexington, April ’75, they left Boston by a naval landing at Charlestown, at the foot of Breed’s hill, and marched out to Lexington by its neck road. The British generals in Boston: Gage, Burgoyne, Howe, and Clinton, realized that, if they were to quash the revolt/revolution, they needed to break out of Boston permanently. They needed to take hold of some easily defended ground — preferably high ground –with a good connection to the rest of coast, and that the obvious spot to attack and hold was the heights of Dorchester, heights that would eventually be held by George Washington. Instead, by incredible ignorance, they changed goals on June 17, and attacked at Charlestown, leaving them with control of another isolated peninsula-community barely attached to the mainland.

What lead four trained Generals to change targets and attack at this worthless spot was the American genius of war: our amazing ability for disarray — plus a good dose of group-think with each General trying to outshine his fellows (too many cooks spoil the broth). The defense of Charlestown and Breeds hill was done incredibly poorly, with only 1200 Colonials participating originally, and even the location was poorly chosen. We’d meant to defend at Bunker hill, with perhaps a secondary foxhole on Breeds hill, but screwed up. We built at night with confused leadership (or no leadership), and a healthy fuel of rum for the diggers. We found when the sun rose that we’d built a bare fox-hole on Bunker hill, and as our main defensive position square trench (redoubt), on Breed’s hill that was open at bak and too deep for people to shoot easily over the side edge. Looking with spyglasses from Boston, the British could see that the trench was a mess: too big, undermanned, and unguarded from the sides. Clearly, the Continentals had no idea what they were doing, and Gage thought to show them the consequences of that. The thought of a quick, decisive victory clouded his mind and the minds of his co-generals to the bigger issue that, even if they won without a single loss, they’d be in a worse position for breaking out of Boston and attacking elsewhere. They’d now have a divided army, and two neck-roads to get through simultaneously. It would be a logistic nightmare.

The attack was supposed to work this way: a sea landing at Moulton's hill. two side actions, SA, at the fronts of the Colonial defenses, and a sweeping main attack, MA, at the edge.

The attack was supposed to work this way: a sea landing at Moulton’s hill. two side actions, SA, at the fronts of the Colonial defenses, and a sweeping main attack, MA, at the edge.

By all rights, any one of the four should have remembered their military goals, ignored the Breed’s hill redoubt, and just taken Dorchester Heights. I guess the incompetence of the rebels at Breeds Hill made attacking there too tempting to ignore. All they would have to do was to get a superior force of trained men on the island and march them forward — or better yet march them around the side of the trench. They wouldn’t even need to fire their weapons, but could have just used bayonets — spears. The Continentals had too few men, no training, and no bayonets. It was expected that even if the Continentals all massed well (unlikely), and shot together (even more unlikely), they would likely miss with half the targets on their first and only shot. If the British marched well, they would arrive at the trench before the Continentals could reload their guns. Even with a frontal attack, a superior force of British would be on the rebels, shooting them at close range and spearing them with their bayonets. The Americans had bought a cannon to the hill, but little powder no idea where to put the cannon. The British plan was to form a line, fake an attack at the front of the redoubt and then wheel: everyone turns right and attacks at the trench’s right side (or left if you look as a Colonial). It should have been a piece of cake.

Unfortunately, the attack was bungled somewhat: landing the troops and forming them up took longer than expected. The British discovered they’d  brought the wrong size balls for their cannon, and had trouble mustering into an appropriate line for attack. In the meantime more Continentals moved over to from the mainland until they outnumbered the British. The Continentals built up the vulnerable, left side of their fort, and built triangular sub forts (Friches) to further defend the sides of the trench. They also built a rough rail fence from the hill to the sea to slow frontal attacks. Some snipers snuck into Charlestown to shoot at British officers from the rear while they were assembling. None of this was critical, but it was annoying. The British wasted more time getting the right cannon-shot, and used cannon fire from ships in the harbor to soften up the Continental position. But shooting up-hill is tricky, and they only managed to killed one this way (decapitated by a cannon-ball). It mostly wasted more time, allowing more digging, and more sniper shooting from town. An enterprising Continental, Col. Stark, put up shot markers at 100 feet and passed the classic instruction: don’t shoot until you see the whites of their eyes, or at least not until your target passes this marker.

The second attack at Breeds Hill

The second attack at Breeds Hill

A first British attack went poorly; a front line of Hessians were used, dressed in bright red coats, topped with the classic, heavy bear-skin hats (Busby hats) to make them look more formidable. They attacked as a line, but the hats kept them from looking down at the muck, bramble and rocks they were stumbling over; they moved slower than was hoped, and never quite managed to wheel. The main attack, at the side, never quite passed the rail fence. A colonial fired early by mistake, and they fired back (bigger mistake). More colonials showed up at the last minute and used the fence to steady their aim. The few British who passed the fence got shot by the retreating Americans as they straggled over. The attack was then called off, allowing the British to re-muster for a second attack, and allowing the Americans to reload (always a mistake). The second British attack used three ranks and was directed more fully towards the fort, but it was similarly unproductive. Charlestown was burnt to stop the snipers, but more colonial soldiers with more ammunition wandered by to help; some from the Bunker Hill group, others from the surrounding mob. Some Colonial soldiers wandered off, too. A platform was built so the Colonials could see to shoot out the side of the Fort (the direction of the last attack). Eventually, the British got enough men together, including some 400 marines shipped over from Boston and some 200 wounded who were ordered to re-muster. They attacked the fort directly as several, well-spaced columns up the middle. This worked in part because it was good strategy, and because the Colonials there were now out of ammunition.

The second attack: Three ranks and no Busby hats this time, with Charlestown burning in the background. Their's not to question why, their's but to do and die.

The second attack: Three ranks and no Busby hats this time, with the dead strewn around and Charlestown burning in the background. Their’s not to question why; their’s but to do and die. Painting by Pyle.

Perhaps, if more Colonials joined the fight they would have beaten back the British a 3rd time, or perhaps thousands would have been captured. As it was most of those on the peninsula were able to retreat before the British completed their assault. The British captured or killed some 400 defenders, mostly during the retreat, and took the peninsula, but lost 1,054 men (226 killed in the battle, the most in the war) plus most of the junior officers. More importantly, the British forces were now divided between two, isolated peninsulas that could only be held with officers and men who would be better used elsewhere. Essentially, the hill they’d takes wasn’t worth a hill-o-beans. They were now too spread out to attack at Dorchester heights, the place they really wanted. By January 1776 they gave up the city and the hill. A main lesson, here and in life: only fight for something that you really want, otherwise you may be disappointed with your win.

There was a remarkable loss of officers, in particular British officers. These were particular targets as they dressed better than the rest. The British lost 1 lieutenant colonel (killed), 5 majors (3 killed), 34 captains (7 killed) 41 lieutenants (9 killed), 57 sergeants (15 killed), and 13 drummers (1 killed). A lesson I learn — don’t dress fancier than you must. Another issue and lesson: after the battle, General Burgoyne blamed Generals Clinton, Howe, and Gage. As a result, Clinton didn’t come to Burgoyne’s aid in June 1777. Instead, stung by Burgoyne’s blame, Clinton ignored the agreed plan, and authorized Howe to attack Philadelphia. Burgoyne’s defeat led to the French joining in on our side, and didn’t do Burgoyne’s reputation any good either. Lesson: be willing to take some blame.

It strikes me that the chaos brought the victory. The choice to defend this peninsula was a mistake, and building a bad fort in the wrong place made it worse. Had Washington been in command, he would have defended the area better, perhaps fortifying Bunker hill instead of Breed’s hill, or fortifying Dorchester. If so, the British would have attacked elsewhere and won with fewer casualties, it seems. That was the result with Fort Washington and Fort Lee in 1776: two proper defensive positions and two solid British victories. But on June 16-17, George Washington was on his way to Boston, and the clowns were still running the circus. There is remarkable comedy to history, particularly concerning the American military. As Bismarck tried to explain to his Kaiser: “God protects children, fools, and the United States of America.”

Robert Buxbaum, August 16, 2015. There are several other howler mistakes of the American Revolution, I’ve dealt with three in a post last month, here. Another lesson: at Lexington and Concord the British unsuccessfully tried to capture Adams and Hancock. By missing them, they sent the two rebels fleeing to the Continental congress in Philadelphia where they were to committed to more mischief than they could have in Boston. Lesson: don’t attack readily, but if you do, make sure you win.

It’s rocket science

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Here are six or so rocket science insights, some simple, some advanced. It’s a fun area of engineering that touches many areas of science and politics. Besides, some people seem to think I’m a rocket scientist.

A basic question I get asked by kids is how a rocket goes up. My answer is it does not go up. That’s mostly an illusion. The majority of the rocket — the fuel — goes down, and only the light shell goes up. People imagine they are seeing the rocket go up. Taken as a whole, fuel and shell, they both go down at 1 G: 9.8 m/s2, 32 ft/sec2.

Because 1 G ofupward acceleration is always lost to gravity, you need high thrust from the rocket engine, especially at the beginning when the rocket is heaviest. If your engine provides less thrust than the weight of your rocket, your rocket sits on the launch pad, and if your thrust is merely twice the weight of the rocket your waste half of your fuel doing nothing useful. Effectively, the upward acceleration of the shell, a = F/m -1G where F is the force of the engine, and m is the mass of the rocket and whatever fuel is in it, and the 1 G is the upward acceleration lost to gravity.  My guess is that you want to design a rocket engine so that the upward acceleration, a, is in the range 8-10 G. This range avoids wasting lots of fuel without requiring you to build the rocket too sturdy. At a = 9G, the rocket engine force, F, has to be about 10 times the rocket weight; it also means the rocket structure must be sturdy enough to support a force of ten times the rocket weight. This can be tricky because the rocket will be the size of a small skyscraper, and the structure must be light so that the majority is fuel. It’s also tricky that this 9-11 times the rocket weight must sit on an engine that runs really hot, about 3000°C. Most engineering projects have fewer constraints than this, and are thus “not rocket science.”

Basic force balance on a rocket going up.

Basic force balance on a rocket going up.

A space rocket has to reach very high speeds; most things that go up, come down almost immediately. You can calculate the minimum orbital speed by balancing the acceleration of gravity, 9.8 m/s2, against the orbital acceleration of going around the earth, a sphere of 40,000 km in circumference (that’s how the meter was defined). Orbital acceleration, a = v2/r, and r = 40,000,000 m/2π = 6,366,000m. Thus, the speed you need to stay up indefinitely is v=√(6,366,000 x 9.8) = 7900 m/s = 17,800 mph. That’s roughly Mach 35, or 35 times the speed of sound. You need some altitude too, just to keep air friction from killing you, but for most missions, the main thing you need is velocity, kinetic energy, not potential energy, as i’ll show below. If you achieve more speed than 17,800 m/s, you circle the earth higher up; this makes docking space-ships tricky, as I’ll explain also.

It turns out that kinetic energy is quite a lot more important than potential energy for sending an object into orbit, and that rockets are the only way practical to reach orbital speed; no current cannon or gun can reach Mach 35. To get a sense of the energy balance involved in rocketry, consider a one kg mass at orbital speed, 7900 m/s, and 200 km altitude. You can calculate that the kinetic energy is 31,205 kJ, while the potential energy, mgh, is only 1,960 kJ. For this orbital height, 200 km, the kinetic energy is about 16 times the potential energy. Not that it’s easy to reach 200 miles altitude, but you can do it with a sophisticated cannon, or a “simple”, one stage, V2-style rocket, you need multiple stages to reach 7,900 m/s. As a way to see this, consider that the energy content of gasoline + oxygen is about 10.5 MJ/kg (10,500 kJ/kg); this is only 1/3 of the kinetic energy of the orbital rocket, but it’s 5 times the potential energy. A fairly efficient gasoline + oxygen powered cannon could not provide orbital kinetic energy since the bullet can move no faster than the explosive vapor. In a rocket this is not a constraint since most of the mass is ejected. I’ll explain further below.

A shell fired at a 45° angle that reaches 200 km altitude would go about 800 km — the distance between North Korea and Japan, or between Iran and Israel. That would require twice as much energy as a shell fired straight up, about 4000 kJ/kg. This is a value still within the range for a (very large) cannon or a single-stage rocket. For Russia or China to hit the US would take much more velocity, and orbital, or near orbital rocketry. To reach the moon, you need more total energy, but less kinetic energy. Moon rockets have taken the approach of first going into orbit, and only later going on. While most of the kinetic energy isn’t lost, I’m still not sure it’s the best trajectory.

The force produced by a rocket is equal to the rate of mass shot out times its velocity. F = ∆(mv). To get a lot of force for each bit of fuel, you want the gas exit velocity to be as fast as possible. A typical maximum is about 2,500 m/s. Mach 10, for a gasoline – oxygen engine. The acceleration of the rocket itself is this ∆mv force divided by the total remaining mass in the rocket (rocket shell plus remaining fuel) minus 1 (gravity). Thus, if the exhaust from a rocket leaves at 2,500 m/s, and you want the rocket to accelerate upward at 9 G, you must exhaust fast enough to develop 10 G, 98 m/s2. The rate of mass exhaust is the mass of the rocket times 98/2500 = .0392/second. That is, about 3.9% of the rocket mass must be ejected each second. Assuming that the fuel for your first stage engine is less than 80% of the total mass, the first stage will flare-out in about 20 seconds at this rate. Your acceleration at the end of the 20 seconds will be greater than 9G, by the way, since the rocket gets lighter as fuel is burnt. When half the weight is gone, it will be accelerating at 19 G.

If you have a good math background, you can develop a differential equation for the relation between fuel consumption and altitude or final speed. This is readily done if you know calculous, or reasonably done if you use differential methods. By either method, it turns out that, for no air friction or gravity resistance, you will reach the same speed as the exhaust when 64% of the rocket mass is exhausted. In the real world, your rocket will have to exhaust 75 or 80% of its mass as first stage fuel to reach a final speed of 2,500 m/s. This is less than 1/3 orbital speed, and reaching it requires that the rest of your rocket mass: the engine, 2nd stage, payload, and any spare fuel to handle descent (Elon Musk’s approach) must weigh less than 20-25% of the original weight of the rocket on the launch pad. This gasoline and oxygen is expensive, but not horribly so if you can reuse the rocket; that’s the motivation for NASA’s and SpaceX’s work on reusable rockets. Most orbital rocket designs require at least three stages to accelerate to the 7900 m/s calculated above, and the second stage is almost invariably lost. If you can set-up and solve the differential equation above, a career in science may be for you.

Now, you might wonder about the exhaust speed I’ve been using, 2500 m/s. If you can achieve higher speeds, the rocket design will be a lot easier, but doing so is not easy for a gasoline/ oxygen engine like Russia and the US uses currently. The heat of combustion of gasoline is 42 MJ/kg, but burning a kg of gasoline requires roughly 2.5 kg of oxygen. Thus, for a rocket fueled by gasoline + oxygen, the heat of combustion is about 10.5 MJ/kg. Now assume that the rocket engine is 30% efficient. Per unit of fuel+ oxygen mass, 1/2 v2 = .3 x 10,500,000; v =√6,300,000  = 2500 m/s. Higher exhaust speeds have been achieved, e.g. with hydrogen-fueled rockets. The sources of inefficiency are many including incomplete combustion in the engine, gas flow off the center-line, and friction flow in the engine and between the atmosphere and gases leaving the rocket nozzle. If you can make a reliable, higher efficiency engine, a career in engineering may be for you.

At an average acceleration of 10 G = 98 m/s2 and a first stage that reaches 2500 m/s you find that the first stage will burn out after 25.5 seconds. If the rocket were going straight up (bad idea), you’d find you are at an altitude of about 28.7 km. A better idea would be an average trajectory of 30°, leaving you at an altitude of 14 km or so. At that altitude you can expect to have far less air friction, and you can expect the second stage engine to be more efficient. It seems to me, you may want to wait 15 seconds or so before firing the second stage: you’ll be another few km up and it seems to me that the benefit of this altitude will be worthwhile. I guess that’s why most space launches wait a few seconds before firing the second stage.

As a final bit, I’d mentioned that docking a rocket with a space station is difficult, in part, because docking requires an increase in angular speed, w, but this generally goes along with a decrease in altitude; a counter-intuitive behavior. Setting the acceleration due to gravity equal to the angular acceleration, we find GM/r2 = w2r, where G is the gravitational constant, and M is the mass or the earth. Rearranging, we find that w2  = GM/r3. For high angular speed, you need small r: a low altitude. When we first went to dock a space-ship, in the early 60s, we had not realized this. When the astronauts fired the engines to dock, they found that they’d accelerate in velocity, but not in angular speed: v = wr. The faster they went, the higher up they went, but the lower the angular speed got: the fewer the orbits per day. Eventually they realized that, to dock with another ship or a space-station that is in front of you, you do not accelerate, but decelerate. When you decelerate you lose altitude and gain angular speed: you catch up with the station, but at a lower altitude. Your next step is to angle your ship near-radially to the earth, and accelerate by firing engines to the side till you dock. Like much of orbital rocketry, it’s simple, but not intuitive or easy.

Robert Buxbaum, August 12, 2015. A cannon that could reach from North Korea to Japan, say, would have to be on the order of 10 km long, running along the slope of a mountain. Even at that length, the shell would have to fire at 450 G, or so, and reach a speed about 3000 m/s, or 1/3 orbital.