Warming up question?

[Buckaroo]

Today I took and members advise and went out to the airport to warm up my 2007 CTSW and get the blood circulating! She's a new plane for me and has been sitting for three week waiting on weather and a CFI check out.

 

The conditions is the hanger are 45 degree minimum temp, Tanis heater for 30 minutes (I got impatient). I opened the big door and pushed her out into a warm Montana 34 degree day with about a 15 knot wind. The big door had to be closed (hanger owner rules) so she sat in the wind for what seemed to take an hour for the door to close. This will be the fourth time I've started the plane and first cold start. I started out with just a slight throttle crack. Then with no success I backed the throttle off and added about an inch of choke. Still no start. Then I added more choke and nothing just prop turning. I think about the time I was going to give up I added more choke and throttle and she came alive. Each time I didn't let her crank long.

 

Now I set her at 2100 and wait for the EFIS to kick to the ready screen. After 10 minutes I give up and shut her down.

 

I did put one strip of aluminum tape on the radiator.

 

Two questions:

 

Any cold start experts out there? In Cessna's I used to just work the throttle fast in and out a couple inch's. I didn't do that on this.

 

Why didn't she warm up after 10 minutes?

[gbigs]

Today I took and members advise and went out to the airport to warm up my 2007 CTSW and get the blood circulating! She's a new plane for me and has been sitting for three week waiting on weather and a CFI check out.

 

The conditions is the hanger are 45 degree minimum temp, Tanis heater for 30 minutes (I got impatient). I opened the big door and pushed her out into a warm Montana 34 degree day with about a 15 knot wind. The big door had to be closed (hanger owner rules) so she sat in the wind for what seemed to take an hour for the door to close. This will be the fourth time I've started the plane and first cold start. I started out with just a slight throttle crack. Then with no success I backed the throttle off and added about an inch of choke. Still no start. Then I added more choke and nothing just prop turning. I think about the time I was going to give up I added more choke and throttle and she came alive. Each time I didn't let her crank long.

 

Now I set her at 2100 and wait for the EFIS to kick to the ready screen. After 10 minutes I give up and shut her down.

 

I did put one strip of aluminum tape on the radiator.

 

Two questions:

 

Any cold start experts out there? In Cessna's I used to just work the throttle fast in and out a couple inch's. I didn't do that on this.

 

Why didn't she warm up after 10 minutes?

 

Letting her sit in frigid temps will lead to all kinds of issues.   You may want to put heat on her for at least an hour (longer is better maybe with a blanket over the cowl).  Then start her right away, don't let her sit.   I have never had carbs in any plane I have owned so can't help with chokes and carbs.  But I know a cold engine will not start and the oil is also thick and a problem (always make sure you burp her, esp in cold temps).  And if you get any kind of water condensation in the fuel lines or the carb it will also inhibit starting.  Also, be careful of losing the battery in cold temps....you may have to put a tender on that too.

[ct9000]

Today I took and members advise and went out to the airport to warm up my 2007 CTSW and get the blood circulating! She's a new plane for me and has been sitting for three week waiting on weather and a CFI check out.

 

The conditions is the hanger are 45 degree minimum temp, Tanis heater for 30 minutes (I got impatient). I opened the big door and pushed her out into a warm Montana 34 degree day with about a 15 knot wind. The big door had to be closed (hanger owner rules) so she sat in the wind for what seemed to take an hour for the door to close. This will be the fourth time I've started the plane and first cold start. I started out with just a slight throttle crack. Then with no success I backed the throttle off and added about an inch of choke. Still no start. Then I added more choke and nothing just prop turning. I think about the time I was going to give up I added more choke and throttle and she came alive. Each time I didn't let her crank long.

 

Now I set her at 2100 and wait for the EFIS to kick to the ready screen. After 10 minutes I give up and shut her down.

 

I did put one strip of aluminum tape on the radiator.

 

Two questions:

 

Any cold start experts out there? In Cessna's I used to just work the throttle fast in and out a couple inch's. I didn't do that on this.

 

Why didn't she warm up after 10 minutes?

 

Use full choke when cold . Close or just crack the throttle . If you use much throttle the choke does not work because it really is not a choke but an enricher.   Takes a long time to warm up the oil. 

[Buckaroo]

Yes I have a tender on her and the hangers 45 which I would guess 45 degrees should be an easy start on the engine. The hanger door and me running out to the plane and starting her is probably 5 minutes in the cold Montana breeze.

 

I think had I know to go with full choke (enrichener) she would of started first off.

[Mike Koerner]

The choke on a Rotax 912 is not really a choke in the sense of there being a plate that blocks some of the air flow and thus increases the fuel-to-air ratio. It's actually a separate mechanism in the carburetor which is completely disabled if you advance the throttle more more than a half inch or so.

I would use full choke for any cold start and leave the throttle all the way back... or maybe just a quarter inch forward.

Mike Koerner

[FredG]

I might not use full "choke" (enricher) at 34 degrees F, but I would use at least 3/4 of the choke travel.  I'm pretty sure my 912 would not start with no choke at 34 degrees F.

[Runtoeat]

Buckaroo, for cold starts in Michigan, which is presently at 28F, I use full choke and no throttle for temps below 40 F.  When temps are above 40F I use 2/3rds choke.  I put a small dab of paint next to my choke lever for the 2/3rds of choke travel during warmer weather.  This tells me I'm at the correct spot for partial choke.  The Rotax is sensitve to too much or too little choke and you may have to find your "sweet spot" for your CT.  Be patient, your didn't wait long enough for the engine to warm up.  It takes a long time to get the Rotax up to 120F in cold weather if you haven't heated the engine prior to starting.

[Buckaroo]

Great insight thanks everyone! My plan is to pre heat the engine with the installed Tanis heater for two hours prior to the flight. I read on this forum a member placing another strip of aluminum on the radiator. I'm moving slowly on this idea as I don't want to fry my $20k engine by a internet post! It's probably a good recommendation but I evaluate and measure everything!????

[Tom Baker]

I use full choke and throttle at idle on the first start of the day, regardless of the temperature. Unless your idle speed is set real low, idle for start should work fine. The choke/starting carburators will also increase the idle speed.

I also try to get off the choke as soon as practical. You will likely have to bump the throttle up at this point.

[BravoFoxtrot]

I have never tried partial choke, so can not comment on that method. I either use no choke if the engine is warm, usually after a restart after haven flown somewhere, or I use full choke. The throttle should always be in the idle position, partly to make sure that you don't start with too many RPMs, and partly because the choke will not be effective with the throttle open. After start, slowly open the choke while increasing the throttle to maintain about 2,000 RPMs. After about 2 minutes gradually increase the throttle to about 2,500 RPMs. Make sure your are in a safe location, set your parking brake, and spend the time going over your pre-checklist, reviewing the upcoming flight, etc. 10 minutes is not an unusual amount of time to wait for the warmup. Adding more tape to the radiator opening at this time won't do you much good. The hottest part of the flight that I have seen is the climb to altitude. Fly it a few times and you will get a feeling for what is necessary. Of course when the outside temperature changes, so will your need for tape!

[Buckaroo]

Wow you guys are great! This forum has helped old Buckaroo go from a total green novice in non CT territory and limited Rotax country to maybe someday a Montana know it all CT and Rotax!

 

I believe I'm the only CT in Montana!

 

Thanks everyone!

[sandpiper]

I use full choke and throttle at idle on the first start of the day, regardless of the temperature. Unless your idle speed is set real low, idle for start should work fine. The choke/starting carburators will also increase the idle speed.

I also try to get off the choke as soon as practical. You will likely have to bump the throttle up at this point.

 

Ditto.

 

Also, in my little part of the great northWET, where we do not have many sub +30F days, I start with one vertical strip of 2" foil tape at 50F and work up to 3 pieces when temps fall below 40F. Just keep an eye on it and if you make a mistake before you figure out what works for you, just come off the throttle and it will cool off in a hurry.

[FlyingMonkey]

I have never tried partial choke, so can not comment on that method. 

 

My experience is that it doesn't work very well.  I use full choke or none.

[FlyingMonkey]

To warm up the oil to a decent temp might take a while, especially in Montana temps at idle.  Might never come up to a good temp.  I'd say once the oil temp hits 100°F or so, you will probably need to run the engine at 3000rpm or maybe higher to get the temp to come up when it's that cold.  I have to run mine a pretty long time to get temp up to the 123°F takeoff temp here in the winter at a balmy 40°F or so.  

 

I don't know how long it would take to hit 200°F or so to boil off any water...it might never do so.  But even if you only get it to 160°F-180°F or so, you still get the benefits of circulating the oil, getting the rotating assembly turning, and lubricating the internal seals and gaskets.  If the temps are slow to come up and don't get very high, I'd run it at least 20min or so. 

[Buckaroo]

Thanks for the tips! I'm no longer guessing my way through this process!

 

I read one person on the forum saying he puts two strips of aluminum tape on the radiator. One across the top like mine but adds another small vertical piece in the middle.

[Tom Baker]

Thanks for the tips! I'm no longer guessing my way through this process!

 

I read one person on the forum saying he puts two strips of aluminum tape on the radiator. One across the top like mine but adds another small vertical piece in the middle.

 

Each airplane is different. Start with one strip and go from there, because it is a fine balance. The oil cooler is behind the radiator, and it is the oil temp that we are trying to raise. The problem is that by placing the tape you are blocking the radiator as well, so coolant temps go up. As you block more to get oil temps up sometimes the coolant temp gets to high.

[WmInce]

My experience is that it doesn't work very well.  I use full choke or none.

Same here.

[FlyingMonkey]

Each airplane is different. Start with one strip and go from there, because it is a fine balance. 

 

You are right about that.  It's very easy to go overboard and get the engine to run too hot.  Even ten degree swings in temperature can have large effects on how much tape you need to use. 

[Buckaroo]

Yes beyond 1 strip makes me a little nervous!