Question about auto gas STC

Aaron Coolidge wrote:

Jay Honeck wrote:

: BTW: What planes don't have mixture controls? (Beside turbines and jets?)
A lot of older, pre WW2 airplanes with small engines, less than 85 HP.

And the newly certified Liberty XL2 (prolly will be the case with all
FADEC engines). I wonder if it will be possible to get an autogas STC
for a FADEC engine like that.

G.R. Patterson III wrote:
: The FAA has nothing to do with it except as the issuer of the certificate. People
: like EAA and Petersen work with one of the plane/engine combos until they get it to
: run reliably on car gas. These people have determined by empirical experiment that
: these modifications are necessary.

True, but my point is that the empirical experiments were done twice with
effectively identical setups. At the time the low-compression tests were done, the
fuel flow was deemed acceptable. At the time the high-compression tests were done,
the same fuel flow was unacceptable. I think either the test "sample" (i.e. airplane)
was substantially different (worn or extra-good pump in one), or they changed the
requirements between the two tests.

Another more subtle change for the Cherokee setup was a change from electric
boost pump being in parallel with the engine pump. Now the two electric pumps are in
parallel, but in series before the engine pump. Not the engine pump diaphram is a
single-point of failure. Also, the gascolator and cabin primer is not on the
*pressure* side of the electric pumps.... subtle changes that have significant safety
ramifications IMO.

FWIW, I talked with Petersen at length about the detonation testing they did
before we shelled out the cash. He said they did quick turn-around flights in a 100
degree day, with 2 mile low-speed taxis in between takeoffs. No vapor lock, and
could't get the engine to detonate... even with 89 AKI cargas. He said he tried to
get the FAA to agree to 89 on the STC, but they wanted 91 for more margin.

-Cory
--
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Jay Masino wrote:
: Wow. That's interesting to know. I wonder if a modified/160hp 140, with
: the Powerflow exhaust would qualify. The muffler is outside the cowling,
: and the collector assembly is in the front, underneath the engine.

Unless they specifically tested that combination, I'm sure the answer is no.
You could ask him, or petition the FSDO (HA HA HA!!!). Since the Powerflow alegedly
scavenges more gasses during the combustion event, the fuel flow could increase a bit
more. Also, the oil cooler isn't in the same place. Most likely it would require
flight testing akin to the original STC certification (read: PITA and expensive).

-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

That's the old pump setup for the O-540 for early Sixes. I'll bet the test aircraft was
an older model with the twin electric fuel pumps in series with the mechanical pump, and
since that was what it was tested with, that is what all planes aspiring to the STC have
to be 'upgraded' to.

wrote:

Another more subtle change for the Cherokee setup was a change from electric
boost pump being in parallel with the engine pump. Now the two electric pumps are in
parallel, but in series before the engine pump. Not the engine pump diaphram is a
single-point of failure. Also, the gascolator and cabin primer is not on the
*pressure* side of the electric pumps.... subtle changes that have significant safety
ramifications IMO.


-Cory
--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

"Jay Honeck" wrote in message news:1cMvc.36339$pt3.35172@attbi_s03...
We had create luck with autogas in the Chief. Kept the engine clean.
The lower octane really makes things run nicer too. 100LL would crud
up the works pretty fast. This is especially bad for those planes that
don't have a mixture control.

I paid $3.30 a gallon for Avgas in Ankeny today!

I paid $1.92 for mogas in Iowa City yesterday.

The math is self-evident -- mogas is the way to go!

BTW: What planes don't have mixture controls? (Beside turbines and jets?)

The J-3 didn't. I believe one of the Chief's didn't. I think mixture
was an optional item on all the 40's 65hp planes. Even when you had
mixture, it didn't do anything on the ground. It only effected you at
cruise power.

The J-3 didn't. I believe one of the Chief's didn't. I think mixture
was an optional item on all the 40's 65hp planes. Even when you had
mixture, it didn't do anything on the ground. It only effected you at
cruise power.

Thanks, all, for the info about mixture-less aircraft. I've only flown a
Cub once, and (apparently) never noticed the lack of a mixture control. (I
don't think I ever touched the throttle -- the guy in back was working the
power...) And I sure had no idea that this feature (or lack thereof) was
universal to so many small-engined, older airplanes.

Another learning experience to chalk up to this newsgroup....

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

As long as we're on the subject of mogas STCs...

My still new-to-me '67 172H already had the Petersen STC installed.

But I've been chicken to try it! Guess I'm concerned that vapor lock or
lower quality or whatever other old wives tales will strike me dead.

Is there *anything* I should watch for if I just suddenly decide to fill 'er
up with mogas some day? Like different start procedure, or longer takeoff
run, or ??? Or, is mogas the EXACT same in every other way (yeah, I know you
guys are gonna chime in with "less bucks, burns cleaner, engine happier,
etc.")

Thanks;
Carl


"JimT96309" wrote in message
...
I am currently interested in an older C-172 (Cont. 0-300 engine) that has
an
STC for auto gas. My questions a

1. Can I continue to use AVgas instead of auto fuel?

2. I often fly into/out of Big Bear City, Ca. (elev. 6500ft.) I've been
able
to get out lightly loaded (me and one in the right seat) at a density
altitude
of 8,100 with one of our clubs 172s with the 320H2AD engines at 160 hp.
What
difference would I see with the 15 fewer horses up front?

3. Can you give me a rough idea of cost to add a 2nd Nav-comm with
Glideslope
and then have the whole thing certified for IFR? I would probably try to
find a
good quality used one from one of the local shops.

Thanks for any help you can give to a rookie getting ready to make a first
purchase.

Jim

"Jay Honeck" wrote in message
news:ZFtwc.45447$pt3.6238@attbi_s03...
The J-3 didn't. I believe one of the Chief's didn't. I think mixture
was an optional item on all the 40's 65hp planes. Even when you had
mixture, it didn't do anything on the ground. It only effected you at
cruise power.

Thanks, all, for the info about mixture-less aircraft. I've only flown a
Cub once, and (apparently) never noticed the lack of a mixture control.
(I
don't think I ever touched the throttle -- the guy in back was working the
power...) And I sure had no idea that this feature (or lack thereof) was
universal to so many small-engined, older airplanes.

There's a few features that older aircraft don't have. Some with the
Stromberg (?) carbs have them safety wired fully rich and use the mag switch
to shut down. It's kind of like shutting off a computer by just pulling the
power cord out of the wall. My mixture control is functional, above 1500 rpm
or so, so in order to shut down from idle, I pull the mixture then firewall
the throttle and it will kill the engine. Other features I don't have on my
plane are rudder pedals (Ercoupe), flaps or a trim tab. It's what makes
these older aircraft 'unique'.

I did my training in a C150 and when I bought my Ercoupe, I had to learn how
to fly without the use of flaps, rudder pedals or a trim tab. There is an
option to add a trim tab for about $600 and rudder pedals can be added but
I'm not interested in those options.

Carl Orton wrote:
: But I've been chicken to try it! Guess I'm concerned that vapor lock or
: lower quality or whatever other old wives tales will strike me dead.

Put it in one tank first. Takeoff on 100LL, cruise on mogas. If you fly less
than 2 hours, you can pretty much burn all mogas that way.

: Is there *anything* I should watch for if I just suddenly decide to fill 'er
: up with mogas some day? Like different start procedure, or longer takeoff
: run, or ??? Or, is mogas the EXACT same in every other way (yeah, I know you
: guys are gonna chime in with "less bucks, burns cleaner, engine happier,
: etc.")

It alegedly will start better... especially when cold because the vapor
pressure is a higher. I've never noticed a difference. I've got the Peterson RVP
gauge and the 100LL tends to have about 1 psi (or inHg... don't remember) lower...
very slight difference, really. The one important thing to do if you put mogas in
your plane is to test it for alcohol. You can google up on the exact procedure, but
it's not hard. Get a clear container, preferrably tall and thin. Put in about 10%
water and mark the level on the side of the container. Add the other 90% fuel.
Shake and then let settle. If the "water" level went up, there's alcohol in it and
you can't use it.

For a low-compression engine, 87 AKI is fine... don't need the high-test. If
you end up running it, I'd highly recommend a fuel filter. I rigged a (very
goofy-looking) pour spout on my 6-gallon cans that has a spin-on water-absorbing fuel
filter (looks like an oil filter) inline. Since I did that, I get absolutely clean
fuel, free of water, and good peace of mind.

Mogas is different operationally in one very important aspect... it *STINKS!*.
100LL is pretty sweet-smelling stuff by comparison.

-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

"G. Burkhart" wrote in message
newspwwc.8392$HG.7233@attbi_s53...
"Jay Honeck" wrote in message
news:ZFtwc.45447$pt3.6238@attbi_s03...
The J-3 didn't. I believe one of the Chief's didn't. I think mixture
was an optional item on all the 40's 65hp planes. Even when you had
mixture, it didn't do anything on the ground. It only effected you at
cruise power.

Thanks, all, for the info about mixture-less aircraft. I've only flown
a
Cub once, and (apparently) never noticed the lack of a mixture control.
(I
don't think I ever touched the throttle -- the guy in back was working
the
power...) And I sure had no idea that this feature (or lack thereof)
was
universal to so many small-engined, older airplanes.

There's a few features that older aircraft don't have. Some with the
Stromberg (?) carbs have them safety wired fully rich and use the mag
switch
to shut down. It's kind of like shutting off a computer by just pulling
the
power cord out of the wall.

Actually it is like shutting off your car. Not a big deal by any means.