Recycled Flyer

Whoa!

All of this really deserves its own thread instead of hijacking this one!

Just to complicate things further, how does one 'really' classify and compare engines in regards to power?

The usual convention of comparing IC engines of similar swept capacity or cubic centimetres/inches seems popular enough because of the ease of measurement but since model diesels use less fuel why would'nt it be reasonable to view it by fuel consumption instead?

This is the way that most of the planets powerplants are being valued, X amount of fuel gets you Y amount of work, and yet in the model world the only two catorgories are that are liquid fuel limited (to my knowledge) are free flight Texico and FAI Team Race.

Looking at it this modern way, fuel consumption vs work done, then a model diesel is far more powerful than a similar capacity of glow engine.
Looking at it this way, an honest comparison would reveal that the cubic capicity equivalancy is a farce and the diesel's volume really should be far larger than the glows if you want to stick to older conventions.
Looking at it this way its more than fair to compare an American LaFrance fire engine engine to a 250cc motorcyle engine because you are viewing 'work done.'

Most modellers are stuck on what cubic capacity is needed to fly a certain model when really it should be what 'weight' penalty the power plant extracts in order to make it functionable.
The model could not care less whether its driven by diesel, glow, electric or even rubber but it does care about wieght it has to carry as a consequence.

And its here that the heavy construction of a diesel with its lighter fuel load is (to me at least) an even comparison to the lighter construction of a glow with its heavier fuel load - the model will never tell the difference in powerplants regardless of the semantics and ravings of its owner.

In regards to 'semantics and ravings' - if thats childish hooey then far more of that is successfully done at most flying fields that I have been to than actual flying - most call it 'conversation' and it is the glue that binds modellers together.

mike109

G'day

I have diesels. I have glow engines. I rarely use the diesels. They are some thing I like because I grew up with them. The first engine I played with was a Frog 150 diesel. The first engine I flew with was an OS 15 (glow). This sums up my whole attitude to diesels. They are for me to play with.

Later I got into racing and the Super Tigre G2015D was great. But eventually a Rossi 15 (glow) went into the same plane (and went faster).

These days I have a few Taipans (I am Australian so it is only natural for me to have some of Gordon Burford's fine creations), an Irvine 40 (because I always wanted one), a MPJet 06 Classic (because it is fun) and most recently an Enya 41 4CD because it has always fascinated me. I have not run the Enya yet because I need more fuel and it is hard to get here.

Diesels do use less fuel but that is not really the reason for buying them. They cannot use Pump Diesel without adding things to it. So the OP's reason for buying one or converting a glow does not really exist.

The reason for buying diesels is either because you like them for their own sake or you want to experiment with them. And of course there are some events, like FAI team race, where they work better than anything else. This is a hobby after all. It does not need to be rational. It is just something we like to do. But buying a model diesel to save a large amount of money on fuel is not a particularly good reason. At least where I live it is not. There may be some places where it is. If you want to save money on fuel, get a petrol (gas) engine. But I don't want models that big and I really hate the smell of burning petrol. It reminds me of mowing the lawn.

Hobbsy

My Feedback: (102)

Now Ed, silly huh, well if its silly to have 20 plus Diesel conversions plus about 6 real Diesels, I must be really silly to have a Harley, a Martin guitar, a fancy bass rod and reel, a beautiful blond wife and 7 kids. Holy moly Ed, I'm nuts.

Now if I only had a Lund Bass Boat with a big black 150hp Mercury on it that would make some sense.

Mr Cox

If you've ever tried it, you would know that your statement isn't true.
Yes, one should optimize the compression on glow engines also, but they will never be able to run the same props as a diesel engine.

123Cat

To me they are real Diesels because they use the heat of compression to initiate ignition , how the fuel gets in there does not matter

And also because you can regulate compression they are more Diesel than any other type because you can manipulate ignition, which I like doing

earlwb

You can use the Thrust HP application to check the engine's power as a glow engine and as a compression ignition engine.

Using a 10x6 prop on a OS 40LA and a 12x6 prop on the same engine as a diesel. It shows a improvement in horspower and thrust as a diesel.

Hobbsy

My Feedback: (102)

When Rudolph Diesel was developing the Diesel some of his first efforts inhaled coal dust as a fuel, it wasn't injected at all. At least one of these engine exploded and nearly killed him. While growing up on our farm in western Pa. I was exposed to Diesels that had direct injection, (Ford), auxillary combustion chamber, (Farmall) and Powercell/energy cell, (Case). I saw hot tube engines at oil wells where a U shaped tube went into and back out of the combustion chamber, you heated this tube by blowing a blow torch flame through it, when the tube was red hot you started the engine.

gkamysz

My Feedback: (19)

Absolutely, but trying to justify it by making half hearted attempts to explain the thermodynamics behind a diesel without actually including any data is taking it a bit far.

There are real world applications for compression ignition engines burning kerosene(no ether) if you can design one and make it do what everyone claims they are capable of here. The reality is that it's much easier to accomplish with a spark plug in the head.

gkamysz

My Feedback: (19)

It's interesting to see a lot of new names at the top reading this thread.

Hobbsy

My Feedback: (102)

You can't always attach numbers to a favorable experience, if you have to justify everything by numbers then why bother in the first place. I like Diesels because I like Diesels no further justification is needed.

KeroPower

To me the model diesel engine is just a novelty. I mean it's fun to have a small diesel powered plane or two, but once you get into the mid size planes (say .40 and above) diesel is just not practical.

It's hard to beat glow:

1. no contra piston to adjust
2. no smell
3. no contra piston that eventually loosens, leaks, and does not hold its setting
4. simple fuel mix (alcohol and castor oil)
5. does not make clothes smell
6. can use an electric start
8. don't have to worry about ignition component evaporating out of the fuel mix
9. no rituals for opening and closing the fuel can
10 don't have to put the fuel can on ice during warmer days at the field
11. can use a tuned pipe
12. no drugs in the fuel

gkamysz

My Feedback: (19)

Dave, I run diesel because I like them as well. I also look at things like BMEP and BSFC. Some of the work I do involves this. Does carrying twice the volume of glow fuel really cripple a model? Does running a larger prop at 2000RPM less really make your modeling experience more pleasurable? The hobby is very technical for some, look at top competitors in any FAI class. They still enjoy it. It's all about the individual experience as you say.

There are of examples of poorly performing diesels or conversions. Recent threads include the PAW .60 and Martins TT07.

I'll refrain from posting technical comments on this site.

BTW, has anyone seen this commercial yet?

[youtube]http://www.youtube.com/watch?v=j0sCCJFkEbE[/youtube]

KeroPower

That must have been expensive. Kind of mean how they stuck the Volt in there at the end.

I see what it is saying, but one has to remember that mostof the electricity comes from burning fossil fuels.

The hair dryer looks like it has a glow plug.

earlwb

Cool video ad, I loved it. It remded me of Tim "The ToolMan" Taylor and his escapades at putting a engne on everything. His gas engine powered screwdriver skit was pretty funny.

These scientists came up with the world's smallest gasoline engine. i guess one could make a gas powered watch with it. It even has a little tiny generator or alternator in it too. Remove the generator and use a propeller and we have a new engine for tiny model airplanes too. I can see a 1/72 scale P-51 with this.

http://www.thesun.co.uk/sol/homepage...ticle80219.ece

Hobbsy

My Feedback: (102)

Greg, technicals are fine, when I was kid I sent a quarter to the University of Nebraska every year to get their latest farm tractor test booklet. I liked to know the PTO hp, drawbar hp, horsepower hours of work per gallon of fuel, bore and stroke, comprssion ratio, cu in and rpm. Tractors were our living. Well, cows were our living but the tractors were more interesting. When it came to tractors I liked the Diesel better too.

NM2K

My Feedback: (14)

But that was a REAL Diesel, Hobbsy. Not a toy two-stroke engine burning spooky ether laced fuel. (smile)


Ed Cregger

gkamysz

My Feedback: (19)

Dave, I had to look up your quote. It's interesting the Google failed. Bing turned up the Star Trek reference.

Hobbsy

My Feedback: (102)

Thanks Greg, the Star Trek Motion Picture was a failure as movies go but not to Trekkies.

Hobbsy

My Feedback: (102)

Ed, I clearly remember two of the tractors hp hours of work per gallon of fuel, one a Case 930 with a 401 cu in six cylinder engine and equipped for propane rated at 90 hp. The other, also a Case 930 wtih the 401 cu in Diesel six, also rated at 90 hp, the propane was rated at 10 hp hours of work per gallon and the Diesel at 20, what a desparity. Another advantage that goes to Diesel was when you hit a big yellow or red clay patch in the filed plowing you almost always had to downshift the gasser but the Diesel would belch a cloud of black smoke and keep rolling.

juanjulian

My Feedback: (9)

IT IS CHEAPER TO GO ELECTRIC IN THIS SIZE OF PLANES.

Mr Cox

Rubber bands are even cheaper, and more exciting than electrics.

juanjulian

My Feedback: (9)

YOU ARE RIGHT

Nice to find you in this threads.

cheers,

juan

fiery

My Feedback: (2)

*intentionally deleted*

Hobbsy

My Feedback: (102)

To me above .40 size is when it makes the most sense, no ignition interference, no awful gasoline stink. And Diesel reliability in flight is second to none, you really have to screw up to get a Diesel to quit in flight. They run smoother than either gasoline or glow.

AMB

Hi Ed think we are in a case of semantics, diesel is compression ignition , regardless of how the fuel enters the engine, glow engines have been called semi diesels that is I think incorrect if the plug goes out the engine stops
most likely the term came from the fact that after starting the glow engine there is no external source of ignition martin

Also the old Hot bulb engines you heated up with a blow torch this was maybe the first glow engine?? where they injected or some sort of a carb??
Hobbsy you know the answer on this one