Ram air in cloud and/or rain?

[Tommy]

Yea or nay?

[FloridaMan]

I close it per POH "impact ice" warnings. 

[orionflt]

no,

you don't want to ingest the water into the intake, Let the filter protect your engine. If you are in heavy enough ran the filter can even get so saturated that it can allow water to get into the engine and cause it to fail. 

there is an article that was written by someone who was flying my airplane (many years before I bought it) through a storm system.

 

http://www.smithsonianmag.com/travel/it-was-a-dark-and-stormy-night-6573553/?no-ist

 

Long story short the engine eventually restarted and he landed safely, but if could have turned out differently.

 

Brian 

[Seth]

Only operate in clear air above whatever altitude you feel that dust/pollen/whatever are located.  For me it was 5000 and above with my former F model in clear air (no visible moisture).

 

-Seth

[RobertGary1]

If you pick up icing conditions the filter will ice over. This is usually not a big deal, you may notice a slight change in sound as the bypass door opens. You should test and lubricate this door at annual. However, the ram air allows ice to get much deeper and the door would not bypass that ice.

 

-Robert

[N201MKTurbo]

So there I was IFR in the clouds coming home from Las Vegas about 25 years ago. I was in my M20F. Motoring along nice and happy at 11000ft. All of a sudden the engine starts to run rough. I fiddled with the controls and after enriching the mixture it started running fine again, but the mixture knob was in further then usual. A few minuets later it started running rough again, more mixture and it smoothed out. It did it again and I had no more mixture to give. Luckily I was right over Kingman, AZ. so I told center about my troubles and asked for the approach into Kingman. The approach was down to minimums. The weather at my destination was VFR, so once again you have to be prepared to do an approach to minimums on every flight! 

 

The plane started to run correctly when I got down to about 5000 feet, but MEAs in the area were way higher then that so I couldn't go anywhere at 5000.

 

It turns out that I had the RAM AIR on and was suffering from icing of the impact tubes. I thought that they should say something about that in the operators manual. That night I read the manual and found the tiny little note to that effect. There should be a whole page with big bold letters that say "DON'T OPEN THE RAM AIR IN THE CLOUDS!"

 

If I recall the OAT was about +2 and I was not getting any airframe icing.

 

When I first started flying IFR in the early 1980s I flew in icing a lot. The rules back then only said you couldn't fly in known icing. If there were not any icing pireps along your route, there was no known icing until you got it on your plane. Then you had to decide if it was bad enough to report and screw everybody for the rest of the day. Anyway, I always had the RAM AIR on because I was young and a speed freak. The only time I suffered the effects of impact tube icing was on that trip over Kingman. So it takes just the right combination of weather to cause it, kind of like carb ice.

[RobertGary1]

Another thing to consider is the condition of your door seals. If you have to oval door there is a rubber gasket around the door. If that wears out you could get moisture, etc blowing past the closed door.

 

-Robert

[N201MKTurbo]

Another thing to consider is the condition of your door seals. If you have to oval door there is a rubber gasket around the door. If that wears out you could get moisture, etc blowing past the closed door.

 

-Robert

 

I doubt it would be a problem. That kind of ice is caused by impact with super cooled water droplets. The ice would form on the door. The air that would sneak around the sides would no longer have the water droplets or so few it wouldn't matter.

[Awqward]

Call me a woose but I never open my Ram air....I'm too paranoid about sucking that seal into the engine....AFAIK for the J it adds maybe 1/2"MP....not worth the risk IMO...in later models (post 1990?) it was deleted...

[MyNameIsNobody]

woose...

[RobertGary1]

Call me a woose but I never open my Ram air....I'm too paranoid about sucking that seal into the engine....AFAIK for the J it adds maybe 1/2"MP....not worth the risk IMO...in later models (post 1990?) it was deleted...

 

yes, its not worth the effort on the J. On the F it adds about 3/4" of MP. I bought my cable from a J owner who got rid of it to save weight.

 

-Robert

[Bob_Belville]

woose

[N201MKTurbo]

I don't think that the ram air inlet is less effective on the J. I think the placement of the normal air filter inlet on the J is much better. It is already in the upper cowl which has a great deal of ram air pressure rise on its own. That is why there is very little difference between the ram air and the air filter.

[Bob_Belville]

The RAM air is worth a full inch of MAP on an E, maybe a little more. But it's only for clean air - no visible moisture - that includes clouds. I use it above 8000 but if I'm in and out of clouds the RAM air control goes out and in. (George is flying the plane, what else do you have to do?)

[Bennett]

Depends on the model and cowl. My J has the LpPresiti cowl, and at 7,500 I get a one and a quarter inch increase in MP There is (was) a great video on the LoPresti website that shows how their ram air works.

[Super Dave]

I guess I'm in disagreement with just about everyone else on this one... I think ram air is fine in clouds or rain, just as long as you are well above freezing. Anytime you are flying through clouds or rain, there is plenty of moisture passing right through your air filter to be ingested by the engine.

 

From my POH: "Turn ram air off if encountering icing conditions...   Therefore, do not use ram air when flying in sleet, snow, rain, or moisture-laden air near freezing conditions" 

[Bob_Belville]

I guess I'm in disagreement with just about everyone else on this one... I think ram air is fine in clouds or rain, just as long as you are well above freezing. Anytime you are flying through clouds or rain, there is plenty of moisture passing right through your air filter to be ingested by the engine.

 

From my POH: "Turn ram air off if encountering icing conditions...   Therefore, do not use ram air when flying in sleet, snow, rain, or moisture-laden air near freezing conditions" 

Dave, your post sent me to the Super 21 Owner Manual, Rev. Nov. '65, covers '64-'66 M20Es. Page 22 says only ...for additional power @ full throttle... "the Power Boost control may be pulled out, provided the atmosphere is free of visible dust." I suppose your '76 F power boost system is the same as my '66 E. I thought moisture was mentioned, I'll have to look around to see where I got that idea...

[orionflt]

I guess I'm in disagreement with just about everyone else on this one... I think ram air is fine in clouds or rain, just as long as you are well above freezing. Anytime you are flying through clouds or rain, there is plenty of moisture passing right through your air filter to be ingested by the engine.

 

From my POH: "Turn ram air off if encountering icing conditions...   Therefore, do not use ram air when flying in sleet, snow, rain, or moisture-laden air near freezing conditions" 

Dave,

You are correct about moisture getting past the filter and into the intake system, but what the filter does is restrict the amount of water allowed. With the ram sir open your engine is free to invest more and larger droplets of water potentially causing engine issues.

Brian

[Bob - S50]

I don't think that the ram air inlet is less effective on the J. I think the placement of the normal air filter inlet on the J is much better. It is already in the upper cowl which has a great deal of ram air pressure rise on its own. That is why there is very little difference between the ram air and the air filter.

 

And if you want more pressure, I recommend the Donaldson air filter rather than the Bracket filter.  When we did that, it might be my imagination, but we seemed to gain about an inch of MP.

 

Bob

[orionflt]

I put the challenger filter on my C model and picked up an extra inch

Brian

[Bob_Belville]

I put the challenger filter on my C model and picked up an extra inch

Brian

I switched to the challenger when I converted to the PFS exhaust. I can't quantify the MAP change but I get just about altitude adjusted MAP vs. ALT setting @ full throttle on take off. I don't know what I got before.

[N201MKTurbo]

I don't know about air filters. My 201 makes 30 in all the way up to FL210

[Bob_Belville]

Dave, your post sent me to the Super 21 Owner Manual, Rev. Nov. '65, covers '64-'66 M20Es. Page 22 says only ...for additional power @ full throttle... "the Power Boost control may be pulled out, provided the atmosphere is free of visible dust." I suppose your '76 F power boost system is the same as my '66 E. I thought moisture was mentioned, I'll have to look around to see where I got that idea...

The MAPA LOG did a series of pireps on the various models. This one on the E has this paragraph:

I didn't get any ram air on data at 10,000 feet because I forgot to activate the door. But as you can see from the 7000' and 4500' data, ram air on adds about 1" hg manifold pressure and 2.5 to 4 KTAS, depending on altitude. Just make sure to turn it off before you descend (I forgot) and don't use it when flying in visible moisture or, heaven forbid, in a sandstorm.

 

http://www.mooneypilots.com/mapalog/m20e.html

 

The test pilot may have been Trey Hughes, I don't see any attribution. I also don't know when the article appeared and finally I don't know whether the "visible moisture" remark should be taken as authoritative. 

[jetdriven]

A few things. Ram air in a J model is different than ram air in the E. The E model ram air has to do an S turn before entering the fuel injector. But the J model opens a straight shot right through the injector. The impact tubes which sense airflow and calculate mass air are exposed, icing these over is a serious deal. I think the E is more tolerant of contamination becuas the air has to turn twice to reach then fuel injector inlet. The E gains more MP Becuase the air box loses 2" or so, the ram Air gives most of that back. The J ram air only gains 1/2" becuas that's only as lossy as the airbox is. The LoPresti cowl actually gains MP above ambient Becuase it has the direct ram

Air, but it also seals off the airbox so the air can actually pressurize a little.

[RobertGary1]

Having flown many types of Mooneys both as a pilot and an instructor I've found that the E and F give 3/4" extra MP and the J gives barely 1/4".

-Robert