Continental C90 with Evra Prop (D11 28 1B)
 

Hi,

I am wondering if anyone out there is running the same Continental C90 / Evra D11 28 1B combination as fitted to my Emeraude ? (I know its a popular combination in Emeraude's & Jodels....).
If so I am wondering if you could advise of the static RPM you normally achieve (assuming approximately Sea level altitute & 20 deg C) as you apply full throttle at the start of your Take off run....
My a/c achieves 2200 rpm static which then increases during the ground run.... This (2200rpm) is the figure which has been entered on the LAA Permit renewal paperwork for both the previous two Permit Renewal Test Flights and it has never been questioned by the LAA engineers so maybe its about right / normal ?
Any wisdom / experience is much appreciated...

Andy Smith

rpm
 

Andy
You'd expect at best 2350 from a healthy C90 with that prop.....
I've seen as low as 2125, and a similarly leisurely takeoff performance.:)
David

Remember that C90 makes its maximum power at 2475rpm (iirc!). So anything over 2150 is going to be fine. A lot over it and you will over speed the engine in level flight.

So I would be pretty happy with 2200 - given that your tacho is probably fairly approximate!

I recall my Emeraude used to get 2150.

C90 figures
 

2625 for 1 minute max (95 hp)....2475 continuous.....
tth

How many hrs since the last TOH? I had a C90 in an Aeronca (well HAL26) years ago and it really benefitted from a TOH - very inexpensive if one does it oneself.

Stik

Thanks for the replies, very much appreciated....

It looks like the take off engine performance may be normal then.... it certainly doesnt "leap" into the air though.

Stiknruda asked about the last TOH..... (technically I dont think it has ever had one..... ?)

However....the last top end overhaul occured 401 Hours ago (7 years) which included a new No.3 cylinder / piston, new piston rings for No.1, 2, 4 & all valve seats cut & lapped. Also at that time, new Oil pump & camshaft gears were fitted.
Then more recently 216 Hours ago (2007) it had a new crankshaft (due to a hairline crack found in the prop mounting flange by a very good LAA inspector - new one supplied & fitted by Isenburg engineering). Also at this time the magneto's had their 500 Hour inspections.

Then 145 hours ago the carb was "serviced & rebuilt" with many new components (float kit, single piece ?? venturi etc).

The compressions feel good during the pre-flight prop swing but I have decided to check the compressions tomorrow morning, I will have to do this with an automotive compression tester as I dont currently have access to a differential cylinder compression tester.... but it should give an indication of any differnces across the cylinders.......

Thanks again for the help / advice / feedback....
Andy