While we are on the topic of alcohol and higher compression. Can

anyone out

there who races tell me if the rotary apex seals will hold up in

higher

compression ratios of 11:1 for a thousand hours or so?  I believe

the

standard high compression rotors are around 9.5:1.

Doug in Japan

You will not get a significant amount of additional power at 11:1

because

the rotary combustion chamber deteriorates quickly as the

compression

ratio

rises above 10:1. Too much surface area so the fire goes out. IMHO
alcohol is probably more affected by a combustion chamber with a

high

surface to volume ratio. Just a wild ass guess on my part. If

higher

CR's  worked Mazda would have used them years ago on the NA

engines.

I know they spent millions researching this.

The rapid increase in Hc emissions as the compression ratio is

increased

is indicative of the combustion chamber's problem with compression

ratio.

Another reason why the Wankel is better suited to turbo charging.

Paul Lamar

Paul

Thanks for the graphs.  Pollution does seem to go up with

compression

ratios. Of course the data is for low RPM ... 2000  with low octane

fuels.

Ethanol is high, around 110 octane.  I think I understand where you

are

going with this line of thinking though. See if I got this right?

With

the

rotary it is more efficient to use the turbo charger to increase

the air

density within the combustion chamber by boosting the volume of air

(and

consequently increasing the pressure) to get it to burn more fuel

and

hence

produce more horsepower rather than by trying to use  engine power

to

compress more air by lessening the depression in the rotor hence

increasing

the compression ratio.

Question??  With the low vapor pressure fuel, ethanol, should I use

the

9.7:1 rotors or the 9.0:1 rotors to get the best fuel burn?  I

understand by

using gasoline Mazda requires the low compression ratio rotors with

a

turbocharger. Detonation issues no doubt.

Doug in Japan

Yes on the first part.

I have no idea on the second part.

Yes on the Detonation issues. That is mainly a question of seal

fracture.

3 mm steel

seals are much more resistant to fracture than stock cast iron 2 mm

seals.

Paul Lamar

Vance W Jaqua wrote:

Doug - If my memory serves me, long duration flights were part of

your plan.

If so,
what is driving you to high alcohol fuels with notably poorer sfc?

also

while
turbo charging provides higher "comprssion ratio", it does not

provide the

improvement in sfc of  NA higher compression ratio . Vance

Vance,

You are right, long flights around the world are part of my plan. Call

it a

lifelong dream or call me crazy, either way its what I gotta do:) Flying

on

fairly clean renewable fuels is the primary challenge.  Route is

secondary.

Documenting the challenge is also important.

A Velocity already went across the Atlantic on 95% ethanol years ago. I
choose the SeaWind over the Velocity because of the former's ruggedness,
numerous landing options, and its documented ability and space to carry

a

lot of extra weight. Running a new engine configuration with biofuels is
risky I know.  I want the option to set down in a sand pile, swamp or

ocean

with a high chance of survival. The SeaWind to date has done this and

more

without damage. As the airplane is being built  I also plan to put a lot

of

hours on the dyno running the engine.  Only when I am totally convinced

it

will work will I go. Even then the first proof of concept flights will

be

endurance flights across USA. With the standard Seawind's installed

IO-540

Lycoming, and 110 gals in the wings, it will go 1400 miles on 100LL.

Counting reserve I need at least a 1200 mile range to safely do the

northern

route. For the southern route a little more than twice that. I'll need

a

ferry tank in the back seat area (on the CG) and  possible another

smaller

tank in the copilots side for longer legs.  The latest SeaWinds with

metal

props and Lycs. weigh in, engine wet, with complete instruments but no

fuel,

at 2400 lbs. I want to knock off 150 to 200lbs. I am fairly confident I

can

do it. That is another story if anyone is interested contact me

directly. It

will be costly though.  I can conceivably carry a total of 200 gals of

fuel,

survival equipment, and still be only 40 lbs over max gross of  3600lbs.

I

have heard of people flying SeaWinds at gross 3800lbs and one case
'shudder' of over 4000 lbs.  I don't plan to do it.

At this time the  northern route is do able, the southern route probably

not

unless we discover some new rotary tricks in the next few years. You
probably know that people island hop across the south Pacific from New
Zealand to Easter Island. After that the shortest great circle route

leads

down into the roaring 40s and into Argentina.  This area is not known

for

its abundance of shipping lanes:)

In certain conditions burning ethanol can approach to within 15% of the

sfc

of gasoline. Its higher octane compensates a little by helping to

produce

more power. To be honest I am still groping in the dark here concerning

lots

of issues with the rotary and ethanol. Baylor Universities' ethanol

research

has all been done with high compression aircraft piston engines.

My present thinking is like this. Since  ethanol benefits from burning

at

higher pressures than gasoline, turbo charging at F.L. 070 to 085  will

help

to normalize the engine and give a wee boost to help the ethanol burn
better. I am fairly certain my no wind speeds (like you suggested) for

long

distances legs are going to done at 120 to 130 knots and that equates to

low

power settings and the need to carry lots of coffee. I am also guessing

that

with a TE-06 turbo on the 20B engine I will have some remaining exhaust
power left over. Turbo compounding is the logical place to send it.
Conservatively thinking perhaps  at least 6 Hp can be returned to the E
shaft.

Your input as well as others is always great appreciated.

Still foggy

Doug in Japan

Doug,

sorry I don't remember, as you for sure metioned it sometime in the past:

Did you already start to build the SeaWind? How far along are you? Any
website to follow the progress?

Thomas J.

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