Flyer59 wrote:
Yes, but as I said, s little over 2500 rpm gives me the best efficiency LOP, and that’s how i will always fly.
You may fly as you like but that still doesn’t change the fact that the lower the RPM, the higher the engine efficiency. The operator manual from the Conti engine used by Cirrus illustrates this well. By hard linking the prop governor, the aircraft loses flexibility, efficiency and gains in noise. On the plus side it gains in simplicity but only marginally so. I would applaud them if they had removed the red lever.
the lower the RPM, the higher the engine efficiency
Ah, now I get it. That’s why I spend so little money on fuel when the plane is in the hangar! ;-)
achimha wrote:
You may fly as you like but that still doesn’t change the fact that the lower the RPM, the higher the engine efficiency.
But that does not take into account the prop’s efficiency.
Each propellor/engine/airframe combination has it’s sweet spot and YMMV, literally !
RobertL18C wrote:
Do many cruise at 2200RPM over square?
I will fly at the MP/RPM combination which is recommended by the engine manufacturer, and if I am given alternatives I will generally choose the lower RPM option even if that means 25" MP/2200 RPM
Wrt “not running over square”, this article by a knowledgeable aviation mechanic and columnist explains that you actually hurt your engine by not running at the lowest possible RPM.
Flyer59 wrote:
that’s better for our discussion which should solely be based on facts).
OK, show us YOUR DATA
edited to remove what might be considered a “personal” remark by the administrator
Keep out the personal stuff please.
Aviathor, good link, Mike Busch’s articles are very good. I knew over square is OK, but didn’t think you might go 12 inches over square on some engines, without risk of detonation.
Michael is right each engine and operator has a different sweet spot, which is probably to some extent subjective. I hadn’t realised the latest Cirrus propeller is four blades, which may have some bearing on slightly higher efficiency at higher RPM, compared to the equivalent two blade prop on a similar engine.
RobertL18C wrote:
I hadn’t realised the latest Cirrus propeller is four blades
There is a thread on EuroGA where Flyer59 describes how he chose his current propeller, including the test flights he made with different propellers.
Aviathor got it, thanks
http://www.euroga.org/forums/flying/3622-mtv-14d-4-blade-prop-for-sr22-t#post_59424
Ok lets get back to the topic at hand otherwise poor Peter will be spending days chopping up this thread to make a dozen new ones.
Here goes:
Average Yearly Costs
Insurance 3K/yr with 150K Hull
Annual 2K/yr includes maintenance before the annual.
Avionics 3K/yr (15% for reserves)
A&P 4K/yr (20% for reserves)
Hangar 3.4K/yr
Subscriptions .6K/yr
Total 16K
Yearly Variable Costs
Flight hours 70 this past year.
Fuel calculation. First hour 20gal/hr (76Lt) Second hour 12.5-13Gal/hr (49Lt) 11K
Landing and airport Fees 1K
Tiedown at transient airports 280 Euros
Handling at various airports 120 Euros
Total 12.4K
So for this past year 70 hrs of flying is 28.4K/70hrs= 405Euros/hr However this includes landing, handling, and parking. All the costs I incurred this past year.
Im not counting my time hanging on the phone with some moronic Phone tree trying to get basic airport information. For some reason I would like to bill them for that since they are so keen to bill me for every little thing at most airports in Europe.
I did not include Cost of money or depreciation of airplane since I purchased it for $47K in ’86 over 29 yrs ago.
I did do major upgrades since that time which really were only partially covered in the hourly reserves.
1. Upgraded Engine IO 550 $65K
2. Upgraded Instrument panel $45K
3. Flint Tips $10K
4. TKS $24K
5. New Paint and windows $18K
6. New partial interior Leather $7K
Total refurbishment Cost $169K Euro price at the time about $1.3/Euro= 130K Euro
Cost for the plane $47K= 36K Euro
Hull insured Value 150K or 16K Euro underinsured.
So Alexis make sure you count the real cost of ownership to include bank costs and delete tax incentives if declaring business deductions.
My costs this past year were higher than normal because I got a load of bad fuel which caused an unnecessary 4K Euro expense. Had to rebuild FCU and fuel pump as well as draining and cleaning the fuel tanks. Got smart and now have security tape as well as a filtered funnel for fueling.
Strange flying 120 hrs a year actually reduces the hourly costs because there is not that much more maintenance required for that extra 30-50 additional hours.
I think airplane partnerships are the way to go not only in Europe but the US.
