Peter wrote:
I am not saying there isn’t a problem; just that we would hopefully see some obvious manifestation of it.
Not necessarily. It’s not that engines are immediately trashed if started below +4°C. It is the damage that is done that shows up at some point later but normally isn’t traceable back, up to eventually shortening the time before an overhaul or other repair is needed. There are many many engines/cylinders that don’t make TBO, and no way of knowing if that is one cause in a lot of cases.
If the oil is not warm enough, then there is a certain period that the cylinder walls aren’t sufficiently lubricated. This just causes unnecessary wear. The colder the start, the longer until warm oil lubricates. Some claim that one cold start is worth 250hr of normal operation….. that is obviously just a provocation, but makes a point. Is there a magic temp? I doubt it.
The other unseen damage can be on the camshaft due to different metal expansion rates reducing tolerances to zero and causing bearing damage. How quickly the engine is heated up after start (i.e. high rpm) would also be a factor here. Maybe the tolerances are enough in 95% of the engines to get away with this, but is a 5% chance worth the risk?
I have just downloaded the EDM700 data from the trip to LFOV.
When I started up, 14th Feb 1000Z, the CHT was +7C. That corresponds closely to the last metar data point (at the top of the list) below.
However the OAT during the night fell to zero:
201902141000 METAR LFOV 141000Z AUTO 12005KT 080V160 CAVOK 06/03 Q1032=
201902140930 METAR LFOV 140930Z AUTO 12006KT CAVOK 04/02 Q1032=
201902140900 METAR LFOV 140900Z AUTO 12006KT 9000 NSC 03/01 Q1032=
201902140830 METAR LFOV 140830Z AUTO 10004KT 7000 NSC 02/01 Q1032=
201902140800 METAR LFOV 140800Z AUTO 07003KT 5000 BR NSC 01/M00 Q1032=
201902140730 METAR LFOV 140730Z AUTO 10003KT 4900 BR NSC 00/M00 Q1032=
201902140700 METAR LFOV 140700Z AUTO 09003KT 4900 BR NSC M00/M01 Q1031=
201902140630 METAR LFOV 140630Z AUTO 10005KT 6000 NSC M00/M01 Q1031=
201902140600 METAR LFOV 140600Z AUTO 09004KT 6000 NSC M00/M01 Q1031=
201902140530 METAR LFOV 140530Z AUTO 09004KT 7000 NSC 00/M01 Q1031=
201902140500 METAR LFOV 140500Z AUTO 10002KT 7000 NSC 00/00 Q1031=
201902140430 METAR LFOV 140430Z AUTO 07003KT 8000 NSC 01/M00 Q1031=
201902140400 METAR LFOV 140400Z AUTO 07003KT 9000 NSC 01/00 Q1031=
201902140330 METAR LFOV 140330Z AUTO 03003KT 5000 BR NSC 00/M00 Q1031=
201902140300 METAR LFOV 140300Z AUTO 03003KT 7000 NSC 01/00 Q1031=
201902140230 METAR LFOV 140230Z AUTO 07003KT CAVOK 01/00 Q1032=
201902140200 METAR LFOV 140200Z AUTO 09003KT CAVOK 02/01 Q1032=
201902140130 METAR LFOV 140130Z AUTO 08005KT CAVOK 02/01 Q1032=
201902140100 METAR LFOV 140100Z AUTO 08005KT CAVOK 02/01 Q1032=
201902140030 METAR LFOV 140030Z AUTO 06003KT CAVOK 03/01 Q1032=
201902140000 METAR LFOV 140000Z AUTO 11003KT CAVOK 04/01 Q1032=
201902132330 METAR LFOV 132330Z AUTO 10004KT CAVOK 04/01 Q1032=
201902132300 METAR LFOV 132300Z AUTO 10005KT CAVOK 04/01 Q1032=
201902132230 METAR LFOV 132230Z AUTO 09006KT CAVOK 04/01 Q1032=
201902132200 METAR LFOV 132200Z AUTO 09005KT CAVOK 04/01 Q1032=
201902132130 METAR LFOV 132130Z AUTO 08004KT CAVOK 05/01 Q1032=
201902132100 METAR LFOV 132100Z AUTO 09005KT CAVOK 04/01 Q1032=
201902132030 METAR LFOV 132030Z AUTO 09006KT CAVOK 04/01 Q1032=
201902132000 METAR LFOV 132000Z AUTO 08004KT CAVOK 05/02 Q1032=
201902131930 METAR LFOV 131930Z AUTO 07005KT CAVOK 05/02 Q1032=
201902131900 METAR LFOV 131900Z AUTO 09004KT CAVOK 06/02 Q1032=
201902131830 METAR LFOV 131830Z AUTO 09006KT CAVOK 05/02 Q1032=
201902131800 METAR LFOV 131800Z AUTO 09005KT CAVOK 06/02 Q1032=
So there isn’t much of a time lag from the OAT to the CHTs. I didn’t have cowling plugs in, which helps the airflow.
What is now needed is data with a blanket over the cowling…
Adding to the myths, does pointing an aircraft into wind make it start easily?
Today we were stuck 20min trying to cold start an aircraft in today’s cold weather (hand starting + no heater), someone come up with the idea and it did work on first try !!
Another chap did come up with a full-blown theory regarding air pressure at intakes/exhausts, but my feeling it was mainly either luck? or from fuel movement?
Ibra wrote:
02
Adding to the myths, does pointing an aircraft into wind make it start easily?
Not unless it is a turbine.
JasonC wrote:
Not unless it is a turbine.
Some of it is true then for other aircraft classes, tough that claim was made for a SEP aircraft that you can lift with one hand, turn it into wind and hand start it like this one turb
I doubt I will be able try that on turbines, especially the hand starting bit 
Ibra wrote:
Adding to the myths, does pointing an aircraft into wind make it start easily?
Can you start the engine by blowing at the propeller instead of hand turning it?
Yes, if you can blow hard enough to maintain a bit over 110kts (that number relates to a C152, other types may vary). 
dejwu wrote:
Can you start the engine by blowing at the propeller instead of hand turning it?
I don’t think that was the main benefit as the required speed will be along what Dave_Philipps mentioned, 30kts wind will not make that much difference while hand propping? Going to the gym does
Say on a 1m prop, 100% engine-prop-speed efficiency where the mags click at 1000rpm, you will need roughly 105kts (188km/h = 1000rpm*100%*1m*3.14*60), of course C172 mags may click at 500rpm but cruise prop efficiency is roughly 70%…
Besides the RPM, I don’t think 30kts wind straight into a SEP air intakes will give that much uplift in manifold pressure, the max will be 90mb or 2.5 inch of mercury
But that wind may make a huge difference on mixture as does a simple carburator choke?
It’s time to pick up this old thread again
The later months of the year, starting with October, produce the most beautiful sunsets.
I guess the challenge for many is landing afterwards – because so many airfields close at sunset.
With another winter here, I came across this from Reiff preheaters.
They use mostly these bands which go around the non-finned part of the cylinders
but they also do a version which is quite similar to my “power resistor” idea above
The above one is only $200. It puts 200W into the engine. Based on my numbers “above” (112kJ/K) that will heat the engine up initially at around 6 degC per hour. Not sure if I got that calculation right…
If it wasn’t for the “hangar politics” I would buy this immediately.
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