My engine coughed!

[asra]

Dave it is very common this time of year to experience icing, as foggy mornings are a norm and this means lots of moisture in the air.When you experience this again quickly land if you can, and if you find the carbies sweating, then its an ice problem.I speak from experience now as it happend to me last weekend in a 912 powerd gyro. Regards Sam. [][][]

[asra]

Hi Mark,I have looked at fuel consumption pretty closely and have a sight tube marked off in 2 litre increments that I check after a timed flight. I get 18 litres per hour at around 40 knots cruise and 20 litres at 45 kts cruise. This is averaged on 2 hr+ cross countries. An hour of circuits will cost me about 21 litres. AUW is 275kg, Disk loading is 1.45lbs/sq' with 23' DW'sAs to Carby icing, NOW it's getting misty but it wasn't the day She coughed. I have some fins extending from the radiator towards the prop to try and help with a cooling issue. One thought is that I'm producing a low pressure area near the carbies with the gap at the bottom of the plate which might accelerate the air slightly past the carbys and reduce their temperature. Anyway the fins are coming off soon to try something else to cool her down. Dave

[asra]

Dave i still cant believe your having heatin trouble with yours, mate mine has just been rebuilt and is tight and i know it is, and i cant get mine over 65*, are you running a thermostat,(i know you typed all this before but i cant remember) if so try taking it out, i'm not running one and it sits steady on 60-65 all the time, the only down side is waiting for the thing to heat up enough for a safe take off temp, send me an email if you like and i'll take a couple of close up pics of my radiator set up.

[Ken Watson]

My twin carb soob did a strange thing the other day. I was cruising at 4250rpm at 1700ft when the engine suddenly increased to 4650. I immediately went to full throttle suspecting icing, but everything seemed normal. Went home and landed. Carbs were sweating. Temp was cool but i didn't think there was that much moisture around. Ken

[asra]

Dave can i get an idea of the engine revs for the above speeds please, i must be just a throttle jockey then hmmmm.Mark

[asra]

Hi Mark,Thanks for the offer re overheating. Sorted it out this week with ver #9 modification. Looks like I'm pressed to get over 65C now although summer will prove the theory. [8D]Seems I had to get the rads up into the airstream and nearer the prop (but not too close hence angled back slightly). Lots of tries with deflector fins etc didn't work. Putting the rads lower would have been easier or a bigger one but didn't want more weight lower...The radiator was mounted low down just to the left of the inspection port where it got almost no clean air. You can see the new bracket now uses this for an attachment point and I've extended the original top ones.Image Insert: 15.95

[Tim]

G'day Dave. You have created a new problem. The further you mount something from the crankshaft on the engine, the greater the amplitude of vibration that it is subject to. Even with the rubber mounts, the origonal radiator brackets ultimately cracked, so it will happen much sooner with your extended brackets. A good test though to prove your theory. The cracking brackets are not a health risk and can be detected in a preflight long before they are any concern. The radiator is mounted such that the total failure of any one bracket will not compromise safety.Tim McClure

[asra]

HeheheThanks Tim, I'll keep an eye on things. Want to take a bet on hours before a crack []?Dave

[asra]

"can i get an idea of the engine revs for the above speeds please, i must be just a throttle jockey then hmmmm." Took her out yesterday, about 10C, 3 blade prop pitched at 11 degrees with 6400rpm max. 40kts 5400rpm, 45kts 5,600+ and 50kts 6,000rpm (& my head gets dragged back!).Thats at max AUW. Bit different on a hot day. My rev counter goes in 200 lots and it was pretty bumpy so not very accurate. I wonder if more grunt makes a bigger difference than less drag given what an open frame footprint is like at speed? For that matter where does weight and the rotor disk diameter and type come in? Anyone know how to juggle all this and what the 'proportions, might be? Dave

[asra]

Hmmm dave i can cruise somewhere between 50-55 knts at only 5200rpms, and max rpms with a three blade timber prop dont know what pitch, is about 6400 i think cause i hardly ever use it on full. so what does that mean, just thought dont know how much difference it would make but my engine is bored out to near the max, so its propably closer to a 600 cc engine than a 582 cc. may have to work it out..Remember -- A good friend will come and bail you out of jail...BUT a true friend will be sitting next to you saying, "Damn...that was fun!"Mark

[asra]

Wow Mark! Do you have a pod or some fairing on your airframe? A picture? Any idea of the AUW? Maybe you are getting an extra 10hp with the rebore. Dave

[birdy]

Is that true AS Mark, or just indicated.??Ignorance is bliss............but only till you realise you were.You can always get the answer you want, if you ask enough experts.

[asra]

Mark the required max RPM on a 582 is 6800, or close enougth, and so if you are only acheiving 6400 then this would be the reason. Your pitch is set for cruise and ecconemy, which means your climb would also be reduced some what.Also what rotors are you using, and what size ?Sam.

[asra]

Dave AUW would be about 320kgs with full fuel, there is a pic in the for sale, the gps says that i'm doin about 80 klms i'll swap it over to knots today and double check the AS, Sam if it will climb better than what it does if i open the pitch up more, i'll scare me self, just thought i've still got my glider vario i might strap it on one day and see what climb i'm gettin.Remember -- A good friend will come and bail you out of jail...BUT a true friend will be sitting next to you saying, "Damn...that was fun!"Mark

[asra]

just remember when you compare GPS with your airspeed guage, that you got no help or hinderence from any wind up there.Don't you just luv it when ASI shows 60knts, and GPS shows 25 knts (hope you got a cut lunch, coz it's going to be a while getin there)[xx(]Russ....A1014 NT....gods country