apereira

I said intercoolers for turbochargers, and actualy the terms are not due to the way they work, as there are turbochargers belt driven as the superchargers are also.

Turbocharge is when the pressure is increased before the air mixes with fuel, and supercharge is when the presure of the mixture is increased(after air anf fuel has been mixed), the supercharged system can not use intercoolers as the mixture is already in the engine and the mixture lowers the temperature already.

On the turbocharger the intercooler lowers the air temp to increase the air mass , thus being able to use more fuel maintaing the stoichiometric constant.

Because supercharging happens in the engine itself it is ussually shaft driven, but on the YS there is no blower, but the concept still applies and that is why is called supercharged engine on the YS. Superchargers do not use cold clean air, as by concept is only related to the fuel mixture pressure increase.

Regards

Alejandro P.

jgg215

It's the compression that heats the intake air, not the exhaust gas.
John

Jetdesign

My Feedback: (8)

Turbochargers (technically 'turbosuperchargers') are superchargers that are driven off exhaust gases. It has nothing to do with when or where the air is mixed with the fuel.

Supercharging just means the engine uses shaft power to compress air prior to intake; I'm sure there are many ways to accomplish this. YS uses a piston compressor rather than a rotating compressor.

Intercooling is to increase the efficiency of a multi-stage compressor, as it is harder to compress hot gases. Basically you take heat energy out of the gas so more energy (pressure) can be put back in. As on the YS, there is no need for an intercooler as it is a single-stage compressor, drawing in cool, (relatively) clean air.

apereira

Arguing about concepts is completly off topic and boring to most. Turbos are associated with centrifugal impellers, and OS had a supercharged engine which did not have an impeller, still supercharged but not turbo, my car for example has a one stage turbo but it also has an intercooler. Maybe I should have explained before turbos can only be before mixture where
supercharging can be before or after mixture, Anyway, concepts are off topic.


Regards

Alejandro P.

TimBle

Thanks for the snotty and unimaginative reply. I do understand the stoichiometry.

Fact remains, the power in gasoline is there, it needs an engine to exploit it. Current two stroke are not there yet. Its a design problem.

Is it worth it for YS to attempt a gasoline engine? Who knows, they are now at CDi Methanol engines. If they design a petrol powered 4 stroke it ma gain some weight but that weight will be ofset by the lower fuel mass that needs to be carried for the same flight duration.

Perhaps YS will go with electric motors in future but that would be quite sad since they've built a reputation as an engine manufacturer for the hobby. Anyone can wing an electric motor and I don't think there's much challenge in it for them. For YS a bigger challenge would a competitive petrol engine so I think they will have a go because it still allows them to maintain uniqueness in a conformist segment of the hobby.

apereira

I think we all agree gasoline engines do not produce the same power a YS does in fair comparison by size and displacement. But one thing to consider is the way YS has developed their engines, and that is to be the lightest most powerful available, and the YS is on the very edge of the mechanical and efficiency design, that is why it is so critical that a defective o ring, not necesarily broken or severely damaged can cause so many headaches, high performance engines are like that, as they are designed to produce every bit of power posible.

Maybe YS could develop a gas version, but if the glow version produces more power and a lighter engine, they will continue to aim at that fuel, I don't really think they care that much for the fuel price, or maybe they do, and that's why they produced the CDI so it can work with no nitro, or up to 25%, which they reduced from 30%, so was it to lower operating cost? or is it because it really does not needs it?

It has been taking YS about two years to come with a new engine for F3A, and that only shows in my opinion the long testing and dedication to their new engines, it happened to the 170 then the 170 CDI then the 175. I think the Japanese market call their desitions(about 460 pilots in their ranking), as in the USA there are only 5 pilots at the Nats flying YS(I think), so a YS gas will be a waste of resources for them?

Has anyone thought about asking Richard Verano about a gas version? Or Yamada himself? Maybe there is an answer already and they have explored that.....

Regards

DagTheElder

Hi apereira,

Just wonder if your calorifc values is Btu/lb?

Further i think your comments are valuable for understanding why thing is as is and why its hard and costly to develop other options.

Best regards

apereira

Hello Dagtheelder,

They are in BTU/Lt I think,but As I mentioned, they are not accurate as That is what I remember from many years ago, the important thing is methanol produces less heat when burns, also Nitromethane even though is an oxidizer also contributes to lower the combustion temperature. Gasoline is much more hotter so it's difficult to control the temperature on a engine with small cooling fins, that's one of the reasons the cooling fins on most gas engines are so big and with a bigger separation between them.

Best regards

Alejandro

MTK

You guys are discussing from a weak position since you don't have any experimental behind you in the model scale.

Forget about turbos and any other mechanical gizmo one could add to a model engine. There are enough moving parts in a 4 stroke to fail at any inopportune time; to me it makes no sense at all for a mfr like YS or OS to put a blower on an engine (OS at least has done that but look how much they sold) to further complicate a model engine and allow more parts that could fail.

Pattern people need "simple" and easy to maintain. The vast majority of you will not take the time it will require to figure out how to run such a rig reliably. Hell you couldn't do it with simple two strokes.... If a mfr decided to build such an engine, who would buy it and at what cost? I wouldn't

The simplest route for liquid power is for a larger displacement, purpose built, LIGHT and QUIET, rear exhaust 2 stroke that uses gas with the YS fuel delivery system. We want and demand simple...this would be the simplest of the liquid burning powerplants. It may not be sexy since you won't be able to boast about your supercharger/blowerific putting 4 pounds of boost blah, blah, blah!!! But how sexy is a simple electric motor turning at 6500 rpm? Better yet, how simple is the electric?

apereira

MTK,

Please read the posts again, where in my case I also said about simple to operate engines and most of your last commenta ,and talked about concepts, not putting a turbo an a model engine, as well as mentioned you are probably the one who has experimented this the most, read again please.

Alejandro

DagTheElder

Hi Matt,
I think you are da....n right in your approach for an viable F3A set-up. any comparison between petrol and methanol will end in the sand. Any mods to a petrol engine can/may be done to a methanol engine. The chemical fact stands!!!!!
An other matter is if one can provide a fuel that is much richer on oxygen to run the petrol engine, but that has not been discussed in this thread. I think I will not paticipate in such chemical debate.

Matt, iam looking foreward to read about your progress with the OS.

Best regards

nonstoprc

My Feedback: (90)

What I would like to say is that gas engines are not reliable as one thought. This is from my experience with rca180, zdz40 fai, dle55, da50, da85 for both pattern and imac. Maintenance (both to the engine and airframe) is constant and too much of a headache for pattern. I have sold all my gas engines since I switched to e-power.

Bill Clark

The heat issue is the same whether the compressor is exhaust driven or engine driven. The act of compressing creats heat. Granted turbos are more efficient (less heat for a given boost) than a roots type engine driven supercharger but the problem still exists. I headed a engine development program recently that used a big block Chevy/ twin turbo setup on gas and at 30lbs of boost the turbos outlet temp was 400deg F. The air over water intercooler dropped the temp down to 120deg F going into the engine allowing well over 2000hp.

Jetdesign

My Feedback: (8)

I was just trying to illustrate the point that YS engines are the most powerful glow motors for pattern primarily due to their supercharging technology. It lets a 1.10 size engine compare to a competitor's 1.50 or more. They've added this technology without external moving parts, basically by adding a simple rotary valve inside the case.

Why not do the exact same thing for gas?

I agree technical stuff can get boring for some; I'll try to keep it below and quoted for those interested in reading. But to me, the topic pretty much looks like "Will YS move their technology into gas engines?" which I think includes discussion on what that technology is, and how appropriate it might be for exploring it's options in pattern.

TimBle

I agree.

Jetdesign

My Feedback: (8)

Or better yet, shaft driven superchargers, like the technology YS is currently using on their 4-stroke glow engines. They've shown us that there's no need for additional moving parts.

I briefly took a look at the Saito lineup - they've got 4-stroke gas engines around the size we'd want for pattern use.

For YS to move to gas/petrol, it is not much of a leap!!

TimBle

IF its a YS petrol then yes theres no much to except changes to reflect the fuel change.

cmoulder

The weight of the [link=http://www.flyrc.com/061122]Saito FG-36[/link] is about 50 oz, without engine mount. Thrust is an anemic 13 lbs.[]

DagTheElder

Anybody,
In this thread there are many consepts to solve the petrol engines lower power compared to methanol.
One thing that puzzels me is the way the debate takes as soon some facts are brought to the table. Some consepts may charge the IC engine with a mixture that will be adequat for surpassing a twostroker in power. But, and excuse me, have the cooling of piston/cylinder been assesed? If one takes into accout that petrol has the least "Latent heat of evaporation Btu/lb @135 while methanol has 472 ". The danger is that a charged petrol engine will not be adequate air-cooled and rapidly will be destroyed. So, to increase power in a petrol engine without external remedies to increase pumping of air into the engine(silenser excluded) a long list of changes to the engine will be necessary.

It has also been mentioned that an increase of BMEP (Brake Mean Effective Pressure) may be increased. (bemp=work pr rev/volumesvept x rev.pr sec. This is also tuning of engine that can/may be done on both petrol and methanol engines. But in my view this complicates the usage of such engine. A successful tuning requires a purpose built tuned pipe.

As long as there is no fuel that has the calorific value of petrol and latent heat of evaporation as methanol, we have in my opinion two choises, listen to MTK or go tune a petrol engine.

Best wishes

vbortone

My Feedback: (2)

Probably a good reason the motocross engines are water cooled now using 4 valves per cylinder. For good reason motocross prefer 4 stroke water cooled engines and two strokes are not as popular. Some years ago (~2003) I saw a 4 stroke gasser in RC scale competition. It was a propotype engine and they had very hard time to get it going. Looks like that engine didn't go anywhere for RC application. Clearly, if YS wants to use gasoline fuel cooling is going to be an issue and water cooled could be the solution but it is not practical in RC application.

cmoulder

This may all be moot with the new battery technologies such as Lithium-Air promising energy densities comparabe to carbon fuels.

Imagine flying a 4kg 2-meter model with a 250-gram battery!

DagTheElder

Bob,
Oh yeah, I have switched to electric myself. Beeing to lazy to maintain engines and planes.

Take a look! http://www.bbc.co.uk/news/science-environment-14852073

Regards

MTK

I might consider switching then if the cost was not prohibitive.

Nah....I just like the sound of internal combustion in the morning and absolutely love tinkering.

cmoulder

Dag,

I hadn't even seen that one yet! They're coming out with new stuff at a furious pace these days.

In Norway, what is the IC:Electric ratio in Pattern?

cmoulder

Matt,

Don't you have a secret electric project going on down there somewhere in the Jersey Skunkworks?