Episode #110 "Dave's New Modem"

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champguy
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Re: Episode #110 "Dave's New Modem"

Postby champguy » Fri Dec 05, 2008 9:51 pm

Good Luck on the FAA getting it's technology sorted out any time soon. They are mostly well meaning types just as we are. The thing that scares me is that we are all running as fast as we can go, we all seem to be carrying hand baskets, and I just hope we are not all going to the same place. You know where it's really hot and the beer ain't cold.
Remember, not all who wander, are lost.
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Re: Episode #110 "Dave's New Modem"

Postby hmltnrgr1 » Sat Dec 06, 2008 8:59 pm

On the subject of the Rotax and using Avgas and/or Mogas, I'm curious: if you're using one type of fuel does the system/tank have to be drained of one before using the other or can they be blended without developing any performance issues :?:

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Re: Episode #110 "Dave's New Modem"

Postby jackhodgson » Sat Dec 06, 2008 10:13 pm

I was wondering just that. If I was flying the Gobosh into some other field, and needed to add fuel, would it be OK to add mogas on top of the avgas. My immediate instinct is NO! I would never mix unless I was certain it was OK.

But it does introduce the danger, in a rental situation, how do I know all the other users do the same? Next time I fly it I'll be looking more closely at the labels and placards in and on the plane to see if there's a warning about this kind of thing.

And I bet that the fuel color would be weird if mogas was added to the avgas.

Anyone know anything about this?

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Re: Episode #110 "Dave's New Modem"

Postby champguy » Sun Dec 07, 2008 11:35 am

A couple of years ago I was flying with some Kitfoxes with 912 Rotax engines. They were using 100LL but insisted they had to add the TCP additive. They also thought MMO was an acceptable substitute for the TCP, why I have no idea. They were not concerned about mixing Mogas. All the people using Mogas in expirimental or certified aircraft with the STC are mixing so far as I know.
The aircraft owner would seem to be the final authority here, particularly with a rental.
Each fuel has limitations. 100LL has too much lead for the plugs, mogas has issues with ethenol, cleanliness, storeage stability, and vapor lock at higher temperatures.
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Re: Episode #110 "Dave's New Modem"

Postby PilotBillFromTexas » Sun Dec 07, 2008 12:09 pm

I was involved working on an O-200 engine that was run on Mogas for a while. I don't care if it is legal, I just don't think that it is a great idea. The backs of the valves especially get all gunked up. God only knows what is going on in places that you can't easily see. If the engineers were counting on a certain type of fuel to be in the tanks, lines and engine then my opinion is to try and stick with that the best you can. You never know what stupid little seal or whatever might not take well to the different fuel or the additives in it.

From what I've seen, people mix fuel all of the time. From a practical matter I don't see how you could avoid it if you are running Mogas. Many, probably most airports just don't carry it. That would mean that it would be really hard to go on a cross country trip without doing a lot of extra work to find Mogas.

I know very little about the Rotax engines and have no experience with them. If they were designed to run on Mogas then I'd be okay with it. I'm counting on the engineers to account for the limitations of the auto fuel in their design.

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Re: Episode #110 "Dave's New Modem"

Postby Dave Higdon » Sun Dec 07, 2008 4:03 pm

Bill, with all respect possible, the gunking up on those valves you describe could well be due to inadequate use of the mixture control in combination with 100LL, rather than MoGas...

Used MoGas about 50 percent of the time in a Cherokee 140 we once owned; in about 340 hours, three annuals and one cylinder replacement, the mechanics consistently commented on how clean the plugs and valves were and racking it up to the use of the mixture knob and the MoGas...conversely, a hangar neighbor flew a 172 (same basic engine, the trusty old O-320 Lyc, 150 hp...), and he fought a lot with lead build up on his plugs and valves...my take on the difference between us was his steadfast fear of ever leaning below 3,000 feet AGL! Density altitude didn't matter, leaning for faster cleaner warm-up wasn't about to be part of his practice -- lest he forget to run full rich on take off and "ruin the engine" as he put it...we shared a mechanic for about 18 month...that same mechanic often tried to hint to him that leaning was a conditional requirement as opposed to a fixed-altitude wrote move...far as I know, he's still struggling with those plugs cause he doesn't like using car gas, even his airplane has the STC making it legal.

And on the topic of MoGas and 100LL in the Rotax 912...never heard of a problem or restriction on mixing the two, just as there wasn't on our Cherokee 140.

But in more than 25 years of MoGar STCs being around, have never heard of an accident attributable to using MoGas or to mixing...there may be one out there...but it's not come on my radar screen...

So wouldn't hesitate using it again in an airplane in which its legal; biggest drawback we found was a little less power on pure Regular MoGas...but not enough to make it a take-off issue...

Dave

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PilotBillFromTexas
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Re: Episode #110 "Dave's New Modem"

Postby PilotBillFromTexas » Sun Dec 07, 2008 6:04 pm

That's a good point. People a lot smarter than me in this area were blaming the mogas on the valve problems so I had no reason not to believe them. What you said makes sense though.

A couple of months back I was doing some flying out in the high plains of west Texas. Alpine-Casparis Muni sits at about 4,500 feet MSL. The C-172 that I was about to fly had a squawk for the engine running roughly. I was with a very experienced instructor who wasn't buying it.

I had leaned one knuckle for taxi and runup. It's an uncontrolled field. He had me position and hold on the runway, run the engine up for takeoff with the brakes on and lean it out right there. The mixture control was out about five inches for proper leaning. We put one inch of mixture back in and took off. No problems from there on out. The person or persons before us probably just wasn't leaning enough.

BTW, I was thinking of you today, Dave. I saw this gorgeous Cherokee 250 taxi by. It was red/white with tip tanks. I had this uncontrollable urge to whistle like when a sexy babe walks by a construction site.

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Re: Episode #110 "Dave's New Modem"

Postby lucaberta » Sun Dec 07, 2008 6:09 pm

StevenPam wrote:As I have mentioned previously elsewhere, I am currently in the process of doing my primary training in a Fly Synthesis Storch - in large part thanks to the efforts of the aviation podsphere (most particularly yourselves, Will Hawkins, and Jason Miller). The Storch seems to have much in common with your Gobosh - all the things you mentioned, at least (though only one throttle!).

ah, Steven, good to know that the guys at Fly Synthesis have yet another happy student pilot in Oz land! Fly Synthesis is an italian company based in the north-east of Italy, and the Storch is a very famous airplane here. It comes with either the 2-strokes Rotax 582 or the 4-strokes Rotax 912.

And yes, you need to know how to use the pedals on such kind of airplane, Jack! I myself had the exact same thought as you had when I first started to fly LSA planes! And a friend of mine, a B747-300 Captain wo flies the Pipistrel Sinus motorglider, told me that he really started to use the pedals much more effectively also on the Jumbo after becoming more and more familiar with their usage when flying the Sinus!

There's alway something to learn! ;)

Happy flying! --L
Luca Bertagnolio, CPL/ASEL/AMEL/ASES/IR

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lucaberta
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Re: Episode #110 "Dave's New Modem"

Postby lucaberta » Sun Dec 07, 2008 6:23 pm

Dave Higdon wrote:Bill, with all respect possible, the gunking up on those valves you describe could well be due to inadequate use of the mixture control in combination with 100LL, rather than MoGas...
[...]
And on the topic of MoGas and 100LL in the Rotax 912...never heard of a problem or restriction on mixing the two, just as there wasn't on our Cherokee 140.


totally in agreement with Dave on this one! Mogas has no lead in it, and thus leaves no traces whatsoever if used 100% of the times like we all do in Italy. It's very difficult to find 100LL in this country, compared to the many fuel stations we have on the roads... so we fill jerry cans and drive them to the strip where we refuel our planes. Some strips now also carry Mogas. 100LL is only found in bigger airports, but its availability sometimes is not guaranteed, unfortunately.

At Oshkosh in 2006 I followed the 1-day class on the Rotax 912 by Lockwood Aviation, and it was pretty obvious that using Rotax engines with 100LL like a lot of people in the US do, causes more troubles to the engine, even if TCP is added. The lead infact will precipitate, and the oil tank will need to be cleaned at every oil change, 25 hours if using 100LL versus 50 hours if using Mogas. The Lockwood trainer was mentioning that the oil tank will show visible lead-based goo that needs to be cleaned out during the oil change, adding to the complexity of the otherwise simple oil change.

My friend SIlvano, who owns a Rotax 912-based Pipistrel SInus motorglider at E45, Calif., always uses Mogas, and had no problems even when climbing to 16000' in order to catch the wave over the Sierras and soar...

Did you ever visit with your friend Clay Lacy at E45, Dave? I met him a couple of times at the monthly PMLAA big bash. And Wayne Handley lives there too! Some nice folks up in Pine Montain Lake, California!

Ciao, Luca
Luca Bertagnolio, CPL/ASEL/AMEL/ASES/IR

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Re: Episode #110 "Dave's New Modem"

Postby lucaberta » Sun Dec 07, 2008 6:50 pm

Given that Jen mentioned skydiving, I got to tell you this story cause it's quite fun... :D

My first exposure to fliying in light planes happened when I decided to skydive, at 16 years of age. My folks were not 100% happy, particularly mom, but had no problem to sign off the papers and so I found myself jumping with static line from a C206 at my home airport of Milan Bresso, very close to where I've spent most of my life.

After the first 6 static line jumps which were part of the basic training, I found that I really liked it, made new friends, and so I kept jumping and soon found myself doing freefall and enjoying it even more.

Of course, some of the friends were the pilots, and we started to talk about flying and what not. Also, I had a good friend of mine ATC at Milan Center, and was spending quite a bit of time behind his back when he was working Milan Approach. So I knew how it was from both the pilot's point of view and the ATC point view.

This thing called flying was starting to be a lot more interesting than expected, but I kept jumping and was about to get to the 100 jumps mark.

At some point, one evening my folks approached me and said: "look, we see that you really like skydiving, but mom doesn't really feel OK when you go jumping, and every time you go skydiving and the phone rings she turns pale and almost faints... we have a deal for you. How about if we pay half the price of the Private Pilot License, at the remaining part will be on you?".

The rest is history. I never made it to the 100 jumps mark! :D

Ciao, Luca
Luca Bertagnolio, CPL/ASEL/AMEL/ASES/IR

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