Serial / Series Hybrid Tracker

[dcb]

Originally Posted by NeilBlanchard

This is the Siemens serial hybrid airplane...

And that is why it won't reach production, because it is stupid. They have a plane and they are still talking in "future tense" about wanting to save 25% of the fuel. They haven't done it yet apparently.

“We want to cut fuel consumption and emissions by 25 percent,” Dr. Frank Anton of Siemens said in a statement.

Well I have already outlined a few ways to do that which have been done before. The series aspect doesn't fit the application, but will probably sucker in a few grants in the process.

[jamesqf]

Originally Posted by dcb

You are advocating convenience over efficiency here, and the larger scale of a commuter plane means greater losses to avoid something as routine as refuelling a car.

But I don't think anyone is talking about commuter planes, they are talking about self-launching sailplanes & light sport airplane. Stuff you fly for fun, and expect to pay for that fun.

I don't know if you've ever flown either sailplanes or small planes, but with either you often fly from small fields where there's no fuel, so either you have to shlep in a bunch of 5-gallon cans, or fly to a larger airport whenever you need gas. With sailplanes, you've got the additional problems of waiting & paying for tows, which is both an expense and a waste of time if you have one towplane and several people wanting to launch.

[dcb]

"The technology, which is intended for later use also in large-scale aircraft, will cut fuel consumption and emissions by 25%, compared to today’s most efficient aircraft drives, according to Siemens."

I have not seen any scope limiting statements. And I don't believe this is all so you only have to schlep 6 gas cans out to the towplane instead of 8.

Tip, figure out how to add just enough fuel + safety margin between tows, quickly, to tow the next glider so you are not spending fuel lifting unneeded fuel into the air.

[jamesqf]

Originally Posted by dcb

Tip, figure out how to add just enough fuel + safety margin between tows, quickly, to tow the next glider so you are not spending fuel lifting unneeded fuel into the air.

Tip: Understand what you're talking about before offering advice :-)

To elaborate, what I was talking about was the WAIT. You have two sailplanes wanting to fly, and one towplane. Obviously, one has to wait 10-15 minutes or so for the towplane to take the other to release point & return. If both are self-launching & electric, the second can depart as soon as the first has cleared the runway, plus you don't have to pay for that expensive towplane at all.

[dcb]

Tip, don't be a complete dumbass

Why are you so bent on not refueling? You are talking about a couple hours recharge time for your imaginary fleet anyway, sheesh! Then after 1000 launches you can go buy new batteries for all of them. Your specific example is just stupid. Escpecially since this is a hybrid thread and you are still going to have to refuel the stupid thing anyway.

If you want a sailplane that can self launch, and has ready fuel then buy a motor glider and go to an airport that has fuel. You make too many problems for yourself, but they are your problems. I don't really care about the nuances of your imaginary amusement park. There are people and cargo to move long distances.

[dcb]

And finally, if the death knell of series hybrid hasn't been heard loudly enough, here then is an actual example of an engine tuned for the task that cannot beat my 15 year old saturn for peak bsfc...

As well as these guys reporting best observed bsfc of a ~235g/kwh gasser which beats my saturn of < 250 by maybe 4% but doesn't come close to a tdi @~195g/kwh being about 20% away.
"I have seen 235 g/KWH on a 625cc per cylinder direct injection (piezo spray guided) Spark ignition engine running at Lambda=1 at best point. Injects at about 200 bar pressure. Engine also has twin cam phasing. 11.3:1 CR."
http://www.eng-tips.com/viewthread.c...185833&page=13

[jamesqf]

Originally Posted by dcb

Tip, don't be a complete dumbass

Tip 1: Don't display your complete ignorance of a subject in public.

Tip 1a: If you must do so, at least do it politely.

Or in other words, it's people who fly (and sell) sailplanes and light planes who're building the electric & hybrid planes. No doubt some are doing it just for the gee-whiz factor, but there's quite a bit of accumulated experience that thinks it's workable.

Why are you so bent on not refueling?

Err... This little thing about CO2, you know? Plus gas prices ($7/gal avgas), the inconvenience, etc.

You are talking about a couple hours recharge time for your imaginary fleet anyway, sheesh!

And so? I fly for an hour or two, then it's parked for days.

Then after 1000 launches you can go buy new batteries for all of them.

Yeah, just like I had to replace the batteries in the Insight after a couple of years. (That's sarcasm - it's still on the original set, 11 years from new.)

[dcb]

Nobody cares about your imaginary problems and self imposed roadblocks. Before you were complaining about waiting for a tow and making money and whining about refueling, and seem to have forgotten that hybrids still need refueling.

Go buy one or shut up.

[rmay635703]

Originally Posted by dcb

Are you also assuming that you have to have a series electric hybrid to use a turbine? Turbines have been powering wheels for a long time, i.e. the hydrokinetic transmission in an M1 tank.

A small 56% eff turbine would never power anything at variable RPM without being a 30% eff turbine, not to mention it ramps up very slow.

That is the reason for a series/serial hybrid is to take advantage of the nearly double efficiency of single speed operation.

Also I didn't mention the motor because there are AC motors that can operate at above 95% at specific RPM and loads, using this as comparison is about as dumb as stating a prius is 38% eff when it really rarely is there except by people who do the extreme pulse and glide to 40ish MPH with prius.

So in other words I am admitting you aren't comparing apples to apples and the real world in both the prius and the situation I described varies from the absolute max in theory most of the time.

Unless of coarse the turbine is putting out exactly the amount required by the AC motor at its peak efficiency in which case battery losses go to zero.

Originally Posted by dcb

How does any of this apply to a "modder" anyway? You going to put a turbine on your citicar?

I would if I could buy one small enough, the only ones I know of that were cut/crimped/dropped into passenger vehicles is when they were rather big vehicles, like the hummers, antique hobbiest cars and some racers.

Also the topic of this discussion was serial hybrids, the situation I described is the only situation that is described in scholarly papers on the advantage of the serial hybrid.

Any other situation is not usefull to persue.

In my round about way I was stating there is promise to serial hybrids but not by using a 5hp Kohlman gas generator to drive your pickup truck 20mph.

[dcb]

I think I know what you are saying, but I do want to draw a line in the sand. P&G is what sets the bar when comparing efficiency, it is entirely well know here and here is where the discussion be. You cannot replace a driver/pilot with a computer and not account for what that driver/pilot can do with mere training.

You have to assume that there will be an optimum technique for operating this hybrid configuration as well, then match up all the speeds/parameters/efficiencies (including charge and discharge losses if it is actually an advantageous strategy) and figure out what a thinking pilot can do before and after. At least then you will know the upper limits on efficiency rather than starting from complete fudge.