Dear Dimona Owners
I'm the owner of the "other" flying Dimona in NZ - and Ian has been a
great help to me in the fine tuning. To address the question about
engine speed and airspeed:
In fine pitch with ZK-GPH the static rpm is about 2900. This increases
to 3000 during the ground roll and peaks at 3300 during climb-out at 60
knots (111 kph). I only sustain full throttle until about 200 feet, at
which point I throttle back gradually to reduce fuel flow (and cylinder
head heating) but the rpm doesn't drop very much. Then at 500 feet I
change to cruise mode.
In coarse pitch and cruise mode the drag increases noticeably above 80
kts. At 2600 rpm I can cruise at 80 knots (148 kph) in level flight.
At 3000 rpm I can usually get up to 90-95 kts, but the speed is
sensitive to even the slightest climbing or diving, and the engine revs
varies with the airspeed.
It seems to me that max power is always needed on ground roll, takeoff
and initial climb, so this is where I like to see 3300 rpm at full
throttle. I'm happy that mine is correctly adjusted. Ian adjusted my
pitch setting (just a tiny amount) to get this peak rpm on climb-out.
The cruise setting is just what you get. The pitch in coarse setting
can't be adjusted without changing the fine pitch as well - the
difference is fixed by the thickness of the centrifugal latch.
As to your question about top speed being 190 kph (that's 103 kts) I can
only get up to that speed in a dive. My peak cruise speed would be
90-95 kts (165-175 kph).
One thing I did with my engine was to replace the thick felt air filter
with K&N type (model RC-1950). I had to make an adaptor ring, but they
fitted in very nicely on both sides. I then adjusted the mixture to
compensate for the reduced resistance at the air intake, using the
colour of the spark plugs and the CHT behaviour as a guide.
Maybe this helps.
Kindest regards
Martyn
On 6/11/19 10:12 PM, Ian Williams wrote:
The RPM’s and speeds are what suits us. There are only 2 Dimona’s
in New Zealand .. some distance from each other.
So it would be good to get data from other Dimona operators.
IW
Sent from my iPhone
On 6/11/2019, at 9:38 PM, Ian Williams <[email protected]
<mailto:[email protected]>> wrote:
Yes … an L2000 Limbach and an HOV62 prop.
What is your static full throttle RPM on the ground ?
*From:*[email protected] <mailto:[email protected]>
*On Behalf Of *Jarek Steliga
*Sent:* Wednesday, 6 November 2019 9:14 p.m.
*To:* Laurie Hoffman via dog <[email protected]
<mailto:[email protected]>>
*Subject:* Re: [DOG mailing list] H36 top speed
Hello Ian Williams,
I am really worried after reading your reply. Are we talking about
H36 with Limbach 80PS and Hoffmann HO V62 propeller? If so, what
could be the reason for the serious underperformance of my power plant?
Regards
Jarek
On Wed, 6 Nov 2019 at 09:05, Jarek Steliga <[email protected]
<mailto:[email protected]>> wrote:
Hi Ric,
1600 hrs / 12 atm pretty consistent on all cylinders
Regards
Jarek
On Tue, 5 Nov 2019 at 12:46, Ric Sutton <[email protected]
<mailto:[email protected]>> wrote:
Hi Jarek how many hours do you have on your engine/ what are
the compressions like?
*From:*[email protected]
<mailto:[email protected]>
[mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of *Jarek Steliga
*Sent:* Monday, 4 November 2019 5:06 AM
*To:* [email protected]
<mailto:[email protected]>
*Subject:* [DOG mailing list] H36 top speed
Hello,
I noticed that at level flight with the prop at cruise angle
I can hardly reach the air speed of 150 km/h at RPM 2500
(full throttle). Is this something to worry about? Should not
the top speed be around 190 km/h at RPM 3000?
With the prop at "start" position the full throttle revs are
3000.
Any comments please?
Regards
Jarek
