Some loud (and crazy) thinking on automobiles...
At iMechanica, almost none talks about topics from structural dynamics and design, theory of machines, automotive mechanics, space mechanics, etc.
Let me help correct this situation by raising two questions below. Well-thought answers from any individual are welcome.
First, some background for the questions.
Most Indian cities were not deliberately designed in modern times but have evolved over centuries. Therefore, the in-city roads are, typically, very narrow, with very sharp turns in the bylanes. Parking space is almost a dream. (BTW, many European cities too carry narrow roads, I have heard, though not as much of traffic congestion.)
So, in such cities, small and low-powered cars should fit ideally. Low power ought not be an issue. At least in India, due to heavy traffic in the city, you can't go above approx. 40 kmph anyways! (Head-on collision is not a concern, but fender-bender is such a routine that none even takes notice of scratches and little bumps for years!!)
For ultra-small cars like Kei cars (and I got to know of the existence of this category only yesterday after browsing Wikipedia), people *have* used engines as small as 100 to 360 cc in the past (in 1940s and 50s). There are others like Smart Fortwo.
Yet, the smallest car in India has the engine displacement as big as 800 cc (Maruti). It has the fuel efficiency of about 18 (km/liter), and costs, say, about 2.25 lacs (i.e. about 5,600 US dollars.) It has brake-power of some 27 kW.
Compare the above data to that for the modern, fuel-efficient motorcycles now available in India: 100 - 150 cc engine, fuel efficiency of 80 to 100+ km/liter, cost of about 0.40 to 1.0 lacs (~1000 to ~2,500 US dollars), and brake-power of about 6 to 10 kW.
Also, keep in mind the data for REVA (electric vehicle for two people with a range of 80 km on a single charge). Cost is 2+ lacs (pl. look-up) and the traction motor is rated at 13 kW (max) DC.
Auto-rickshaw: 175 - 275 cc, 6 - 7 kW, 30 km/liter
Now, the two sets of questions I have.
(1) Why can't manufacturers introduce car smaller than Maruti-800 for markets like India (and many other developing countries)?
I have no details on Tata's Re. 1 lac (2,500 USD) car. But the electric car REVA has even smaller wheel-base, which makes it far more easily maneuverable.
My idea is to have a petrol/diesel car of a size that falls in between REVA and Maruti-800, but of low power (just about 300-400 cc). It would be ideal for many Indian cities. You don't even need 500 cc. The choice doesn't have to be the lowly three-wheeler auto-rickshaw (which doesn't even have doors) and then, directly the Maruti-800 car. I think there is a lot of space in between. So, why not have a car in between? Are there any suppressive government controls? Are there a lot of licensing hassles (like a lot of road-safety tests) if I make a small car out of hobby?
(2) Trains can easily run on two or three engines--synchronization is not much of an issue there. What technical problems would arise if I directly put two 100/150 cc motorcycle engines, one each for the front and rear axles, without any transmission directly connecting the two engines? Say, with a mini variety of automatic gear transmission, separately for each axle? (Or, simply, the continuously varying belt.) There could be some embedded electronics to synchronize their running.
The transmission losses could come down this way. Another advantage is that the car will have redundancy built-in. (Even if one engine fails, I don't have to tow the car--I could at least make it back home.) An ability to keep one engine completely switched off if only one/two people ride the car is another (boosting the fuel efficiency). Availability of service expertise is yet another bonus.
With this dual configuratino, I could easily get, say, 15 kW of power (enough to make even difficult in-city gradients with 4/5 people), about 75 kmph of top speed, and about 40 km/liter of fuel efficiency (or much higher, if one engine is switched off while cruising), with far greater maneaverability, 1/3 less parking space. There are bound to be other advantages...
Of course, none puts two engines on two axles in the same car. I am sure people must have thought of it in the early history of car designing and then given it up for some good set of reasons. So, I am sure there are bound to be a lot of disadvantages. What are the glaring ones? And are they enough, in the modern context, to give up the idea of the double engine car?
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More on double engine car
On second thoughts, I like the idea even better. A few addenda and modifications.
0. I am perhpas depriving myself the opportunity to file patents and make money by publishing my ideas here.
But I think publishing my ideas right away, letting go the opportunity to own patents is necessary.
If I publish here the idea, it would spread around the word that I do know many of the core mechanical engineering topics reasonably well. This would, in turn, eat into the objections raised as recently as last month that since I don't have my master's or bachelor's degrees specifically in the mechanical engineering branch, therefore, I am unfit to do the relevant jobs even after nearing completion of a PhD in mechanical engineering--jobs in the CAE field, in stress analysis, in software development for CAE applications, etc. ... That way, no matter how spurious, this objection is not new: Professor Amarnath, the then Head of Mechanical Engg Dept of IIT Bombay, with his PhD from Moscow, USSR, had expressed exactly the same opinion in 2003, and thereby kept me out of IIT Bombay. (It also meant keeping me out of scholarship for my PhD.)
It is thus that this idea of mine now goes public, "thanks," in part, to Prof. Amarnath, and several alumni of IIT Bombay over the years, and their spiritual brothers and colleagues elsewhere too (including graduates of Ivy League schools):
1. OK. Back to the new double-engine car. The idea is simple. As a modification to the above, the two engines *don't* have to be fully synchronized!
Just keep one 150-200 cc engine at front, with the standard, low-cost, *manual* transmission. This would be the normal drive of the car. (For example, though not necessarily, it could be the engine+gear box of Bajaj Pulsar.)
Then, simply add another engine, with belt-CVT, on the rare axle. (For example, but not necessarily, it could be the engine + transmission of Kinetic scooer.) With some simple embedded electronics (getting its input from the front engine), the rare engine would be kicked in and out of the power *on the fly*, in fact without any manual intervention from the driver. Note, there won't be any need to do synchronization by speed.
The driver would continue to get the sesory feedback (of engine sound, the expected jerk at the change of gears, etc.) from the nearer, front engine.
The solution involves minimum components and adaptation costs, but give a definite benefit.
2. On second thoughts, I think, the power could be slightly higher: 15 - 18 kW. The maximum speed could be as high as 90 km/hr on plain road (highway, without gradients).
3. The weight of the car ought to be < 500 kg. Use composites, polymers, easily replaceable glass panels. (Details of materials and mechanisms, later.)
4. The engines would be accomodated in part in the space below the passenger seats. This way, the hood space is no longer necessary. This allows smaller wheel-base and better maneuverability. The wheel-base could be comparable to auto-rickshaw.
Look at Maruti 800, Indigo, or any similar car, sideways. In the profile, I see a lot of space wasted in keeping the hood in front, with that much less space left to people. It is as if people were a secondary consideration in these cars.
The solution is to have smaller space to engine.
In my solution, "the engine" is not of one piece, but gets distributed in two parts, and so, each part is that much smaller. So, in my car, more percentage of the total space enclosed by the car's external surface is available to people (and their luggage).
5. Tubular structure to encase the entire passenger zone. More on the human-factor engineering and aesthetic design of the car, later.
6. Note, the fuel-efficiency of 40-70 km/liter, which is *really* variable, depending on the load and other conditions, but easily at around 50 km/liter for two people. Compare it to M800 average of 16-20 km/liter. Also note, fly-overs in the city would be easily negotiable.
7. Even without economy of scale of production, the preliminary estimates are obvious that the car could be built for less than Rs 1 lacs--may be, even about Rs. 75,000/- or so, going by today's market prices.
8. Small workshops and entrepreneurs from Pune-Mumbai region may get in touch with me for discussions.
May not be too practical!
One thing you must consider is that Engines are not electric motors. They cannot be switched off and on by the flick of a switch or through control electronics.
When not being loaded they need to run idle (for short stops). And in city traffic this is very very important. That is why you have neutrals, plate clutches or centrifugal clutches in vehicles.
Now if you have multiple engine vehicles, you would need to switch the secondary engine on and off several times and that is not possible without cranking the engine!
You talk of trains having multiple engines at either end. Well in the current scenario, trains have diesel electric engines! Diesel generators run AC/DC motors which can be controlled and started and stopped precisely and easily without the need of speed and torque adjusting gearboxes (where you can change gears). That is exactly why trains have diesel electric engines.
Electric cars too have multiple motors, sometimes one for each wheel. Again simply because they can be controlled individually, very easily.
But that can't be done easily in engines. Now in Hybrids like the Ford Escape Hybrid or the Toyota Prius, the engine can be started and stopped whenever needed as they are normally not powering the wheels directly. They charge a battery and the car runs on electric motors. When additional power is needed, the engine switches on, and charges the battery. So even when the car is stationary, the engine can be running without idling. It is generating power which gets stored in the batteries.
So your dual engine strategy may not work too well! Will be a rudimentary vehicle with a lot of energy loss.
Even 50 kmpl will not be achievable easily. Simply because both the Pulsar engine and the Kinetic engine (which is even less efficient than that of the Pulsar) hardly offer more than 50 kmpl under normal riding conditions. Add more load and two engines running concurrently, how much do you have?
Talking of space.. Cars have evolved over the years from being horseless carriages. "Wasted" space in the front is not wasted. It forms essential crumple zones or atleast a barrier in the event of a frontal crash.
Ask anyone how safe is a Maruti Omni vis-a-vis a Tata Indica or even the 800?
Cheers,
Glifford.
It is practical...
I will, for once, break my general rule of not responding to anything being written by "empty" profiles and so replying only to individuals. I do think that people ought to have enough sense of fellowship and responsibility that they give their name, affiliation, etc. Yet, here, I will break that rule of mine for once and reply.
1. My idea (spelt above) is practical, full-stop.
2. About your point concerning neutrals, idling, cranking, etc. I suggest you to check out the articles on automatic transmission (e.g. on CVT) at Wikipedia.
Or, alternatively, you might want to take an actual ride on a "gearless" moped, and observe precisely how the engine and the transmission work together when, for instance, in the middle of cruising at 55 kmph, you let go the accelerator for some time. What, precisely, happens then? And what happens when you again raise the accelerator? Take an actual ride and see if your point about "being not loaded" makes sense.
I think I should not mention about electronic control of gear shifting etc. Going by your reply, it would be something of an advanced consideration.
3. It's a wrong notion that electromagnetic fields (and devices and machines based on them) come without the "matter-like" attributes like time-delays, hysteresis (or friction), inertia-like effects, etc. Albeit wrong, this notion is very widespread, primarily because the introductory courses in physics and engineering often only discuss EM fields in material-free space (and for the range of phenomena where frequency is very high).
But the reality is that even electric machines won't respond "at the flick of a button." Agreed, they are more responsive (esp. the small and specialized motors like the stepper motors). But the point is, the reasonably bigger machines, even if electrical, do have something like "performance characteristics," don't they?
(BTW, while on this topic, I might as well mention here that it always surprises me that it always surprises people that fluidics can give a much better or finer control as compared to electronics.)
4. Diesel electrics have been around for a long time. Perhaps for 50+ years or so, I don't know. In any case, the idea has been around for sufficiently long time that such a nature of theirs (disel engine->generator->motor) was mentioned in those very old Indian text-books (like Khurmi and Gupta) right in late 1970s, when I was a first year UG student. [BTW, nope, I couldn't rely on those Indian books. Too poor quality. So, I ended up using Fitzgerald (McGraw Hill) and Hughes (ELBS). But the point is, even those Indian and old books had already mentioned this point about diesel electrics.] So, this point you make about diesel electrics is not at all a recent development.
More importantly, the reason you cite for using electric motors in trains is wrong (in the sense, misleading).
The main reason is not the ease of control, or the ease of starting and stopping. The main reason is the availability of comparatively high levels of torque right at the beginning, i.e. at relatively low speeds (or RPM). Especially, for the DC motors. That's the reason they go through all that loop.
5. "So your dual engine strategy may not work too well! Will be a rudimentary vehicle with a lot of energy loss."
Can you support that statement with any credible references and / or sound reasoning?
6. About fuel efficienty.
As to your statement about the fuel efficienty of Pulsar, I will leave it up to the Bajaj Auto marketing people to respond and correct you (if they wish to). But it does seem like the data you suggest could be for the 200+ cc engines within the Pulsar range.
Now, roughly around the same time that you posted that statement, I was watching a recent Bajaj ad on TV. It said something about an engine that is waiting for a bike. (That was that usual marketing sort of twist on that old one about a solution waiting for its problem!) This ad claimed that they had this 125 cc engine that gave 109 km/liter. (The ad was about the DTSi engine or something like that.) Similar ads have been put out by other manufacturers too. I have noticed figures upward of 90 km/liter with 125 cc displacement engines.
So, I thought it reasonable to have 150 cc and 80 km/liter under standard conditions.
If so, then, With a < 500 kg mass, I estimate 40 km/liter for my car. I think such an average is reasonable. I am willing to correct myself. But the point is: If my car isn't fuel efficient, then so aren't other vehicles--m/cs and scooters and auto-rickshaws and other cars included. The whole game is comparative.
Even if my car does the average of just about 35 km/liter under the city driving conditions, it would still beat Maruti 800 by a multiplying factor of 2.0, and many other smaller cars by a factor of about 2.5 to 3.0. Note, I am talking about *multiplying factors*, not percentage points. (So, in percentage terms, it's 200% to 300% boost.)
And if the car does 35 km/liter in the inner city roads, there is little reason why it couldn't *cruise* on highways with an efficiency of 50 km/liter. With only two people sitting, it could even go as high as 70 km/liter. (The higher figures in the range seem reasonable in the absence of adverse wind conditions.).
Actually, this whole logic about fuel efficiency cannot at all be overemphasized. It's a very simple and straight-forward matter, with little scope for argument. If you (i) reduce the weight and (ii) use a lower-power engine, and (iii) optimise engine running, you are *bound* to get a very good mileage, full-stop. Plain common sense. The absolute figures may vary, but the percentage boost of 200% to 300% will always be there.
The un-common sensical thing here is not the mileage figure I claim but my sheer observation (and recommendation) that the *lower* power engine is good enough for a certain set of driving conditions and a certain kind of car (which fits those circumstances).
The real novelty is with *this* observation. Especially, even if the recent trend has been for ever more powerful bikes (illustrated by the success of Pulsar) and for faster cars (illustrated by a whole array of them).
So, the audacity is only with that idea of using a lower power engine. And, of course, the audacity also lies in using a second engine. But the audacity is *not* with the claims of fuel efficiency, technological feasibility, or practicality of driving one.
6. About your statements regarding front-engine and space. : "Cars have evolved over the years from being horseless carriages..."
I wish you had checked the history of cars more carefully before writing that way.
You could start with a picture of the Ford Model T (1910s, 20s). Why, if you are from India, you can have a look at those vintage Austins (1940s).
None of the early cars I know has ever looked like just the carriage portion of the horse-carriage (i.e. a box, sort of like Maruti Omni, or the older Tempo Matador). None. (BTW, I am aware of the very early "cars"--and not trams or rails--which were fitted with coal-fired steam engines, but that's a different story.)
To the best of my (limited) knowledge, all the old cars followed the present-day routine design of giving up some 1/3 to 1/2 space in front to the engine, thereby taking that much space away from the people. (I am not a car history buff, but among the popular or best-selling models at least, it was Volkswagen Beetle that first came with a engine at the rear--in 1950s, I guess.)
So, your assertion is mostly wrong. If there was any car that didn't have 1/3 to 1/2 space going to hood, it would be an historcial novelty--not a wide-spead step in an evolution.
7. About the crumple zone.
"Glifford," you just reversed causality.
It's *because* the engine is anyway sitting there right in the front that the designers have designed the *linkages* and *fittings* and other parts in such a way that, other requirements fulfilled, these parts could also be more absorbing of the impact energy.
*Not* the other way around.
The designers didn't put the engine in front with a view to absorb the energy of impact. If such were to be the purpose, they surely could design a far more efficient scheme. An engine is a very poor structure for absorbing impact.
Here, I also wish that you would re-read the specs I have outlined above. In particular, I have said that the head-on collision is *not* a concern; fender-bender is. It perhaps also could said, of course jocularly, that in the small Indian cities (or on the narrow Indian in-city roads) the fender-bender is such a common occurrence that it cannot be elevated into a major design concern!
It's a separate story that fender-benders is a concern that is not at all paid any attention to, by any vehicle designers (2, 3, or 4 wheeler).
For my car, there will be easily replaceable fenders or panels. The bumpers will be integratedly built into the car chassis.
Another point. Due to the same road conditions, what the specs require is the ease of maneaverability. Shorter wheel base gives you that.
Now, a word about passenger safety. I did say: "tubular structure to encase the entire passenger zone." That is, a "cage," if you want that word.
I mean a Bucky-ball-like, efficient, and an optimum structure that can keep passengers safe despite the low to medium levels of impact. A structure of this sort isn't found in any of the vehicles, at least those currently in the Indian market.
And remember, my car is *not* at all meant for use in high impact situations.
Yes, that is its down-side, limitation, Achille's heel, etc. Call it what you may. There is nothing to be hidden about it; it really is a design feature. This car *would* do badly in any high-impact situation. People should take care to drive it accordingly, which isn't asking for a lot.
But if you find my above statement shocking, consider the two questions from a practical viewpoint:
(i) what are the consequences of being in a usual car, say an Indica or a Santro, if you get involved in a high-speed accident on a super expressway (i.e. in a high-impact situation)? You *anyways* aren't very safe even in such cars--the cars that are comparatively more powerful, bulkier, weightier and gas-guzzling. (If bulkier and more powerful cars automatically meant safer cars, Volvo wouldn't make so much safe-car business, would they?)
(ii) Do you actually worry about head-on collisions when you signal an auto-rickshaw to stop for you, when you are going for a quick ride to a multiplex--say to a movie along with your girl-friend? And even if you yourself do worry (about head-on collisions), do you think that the rest of the world does? If so, how come all those three- and six-seaters get sold (and used) by millions?
Now, of course, the passenger safety is an important consideration. I don't deny that.
My car would do pretty well under low and medium impact situations. Even under the high impact situation, my car won't do as badly as might be naively imagined, and that's because of the "cage" structure. It really is beautiful.
The cage is a Very simple structural principle. I don't have the time to discuss its details or finer aspects, but check out on the Internet things like the Bucky ball, or, the egg-dropping competition and the kind of structure that can at all keep the dropped egg safe. It's invariably the cage type.
The cage of my car will be more efficient than those found in comparable cars.
8. "Glifford," I think I have been more than accomodating in replying to "you" even if I don't know "your" identity or background.
What if you are a manager in charge of marketing with Tata Motors? Shouldn't you identify yourself then?
If you do not wish to tell who you are, you might as well keep off my posts. Please take this matter very seriously. Especially, if you are going to write without studying the matters well enough.
9. Before closing, I do not deny that double engine cars might not have synchronization or other issues. They could.
But my point is that the first reaction to this novel concept is often based on some feelings whose actual bases are either totally off-the-mark or are outright outdated. On the second count, check out the progress in transmission. (For instance, did you know that auto-transmission can bring about up to 20% boost to fuel efficiency? I myself found the figure a little on the higher side, but it seems to be the case!!)
10. To conclude: My car makes a lot of sense. The idea indeed *was* patents-worthy: It is an economically sound and a very practical idea--and a fitting one *for its specified market*.
(And I do believe that the market exists for this sort of car. Ask anyone who sold his old scooter of some 30-35 km/liter average and bought a Hero Honda of some 55-60 km/liter average, in the early 1990s. They will confirm what I say.)