Hi Ian, I have just stumbled upon this article https://www.aopa.org/news-and-media/all-news/2005/august/pilot/soar-like-a-sea-gull where I found the following statement: " Acceleration is satisfying, especially after you discover that the engine, which nominally produces 80 horsepower at 3,400 rpm, only puts out 50 horsepower or so in the 2,500-to-2,800-rpm actual operating range."
This made me think again if perhaps my Dimona is flyable after all even if it clearly falls short of your benchmarks. The fact is that prior to the recent replacement of the throttle shafts and butterflies, the engine used to rev up to 2700 static, but it was pretty erratic and uneven and I remember distinctly I could hold the plane in place with just the use of the handbrake (no choks), while now I need the chocks even if the max RPM are just 2500. I wonder if you would find time and interest to have a look at this article. Best regards Jarek P.S. I discovered with some satisfaction that you have some Polish made (or at least) designed gliders like PW5, Cobra and Puchatek in your fleet. On Fri, 3 Jan 2020 at 21:58, Jarek Steliga <[email protected]> wrote: > Hello Ian, > > Thank you again. I know enough. There's nothing for it but to roll up my > sleeves and find the reason for this slow rotation rate of my machine along > the suggestions made by yourself and other people under this thread. I am > going to report to you when/if I manage to rectify the situation. > > Best regards > Jarek > > > > On Fri, 3 Jan 2020 at 21:27, Ian Williams <[email protected]> wrote: > >> No it’s not spectacular really. We have a older Grob 109 which I >> refitted a 2400 Limbach into some years ago. It can cruise at 95 to 100 kts >> However the Dimona is much better at the slow speed end. It is very >> stable great thermalling stability. It can thermal well at 45 kts Wheras >> the Grob 109 begins to get uncomfortable if u get below 55 kts >> >> Best regards >> Ian Williams >> ZK-GCB >> >> Sent from my iPhone >> >> On 4/01/2020, at 8:43 AM, Jarek Steliga <[email protected]> wrote: >> >> Hi Ian, >> >> Thank you. Yes, I remember you mentioning these figures before. I am >> wondering if your plane is exceptionally fast. Do you think the other >> owners enjoy the similar performance? >> >> Best regards >> Jarek >> >> >> >> On Fri, 3 Jan 2020 at 19:21, Ian Williams <[email protected]> wrote: >> >>> hi Jarek, >>> Typically I look for close to 2800 to 2900 RPM static as part of our pre >>> take off checks to confirm the prop is in fine pitch >>> On climb out provided the airspeed is around 60 kts or so the RPM gets >>> to about 3200. Any more and the noise factor increases >>> Best regards >>> Ian Williams >>> ZK-GCB >>> >>> Sent from my iPhone >>> >>> On 4/01/2020, at 4:55 AM, Jarek Steliga <[email protected]> wrote: >>> >>> Hello, >>> >>> I apologize for laboring the point, but what is the max static RPM on >>> your H36 / Limbach 2000 / Hoffman H0-V62 prop? Do all of you reach >>> consistently way above 2500 RPM? >>> >>> >>> Best regards >>> Jarek >>> >>> >>> >>> On Wed, 1 Jan 2020 at 12:28, Jarek Steliga <[email protected]> >>> wrote: >>> >>>> Hello Rob, >>>> >>>> Thank you for your reply and all the best in the New Year! >>>> >>>> Yes, I have synchronized the carbs with vacuum gauges. The readings >>>> were pretty consistent throughout the range of throttle opening. However I >>>> noticed how throttle butterflies will not track together as they open wide. >>>> They are both fully closed at idle but aren't aligned at full throttle. >>>> Should this worry me even if both sides seem to be synchronized when it >>>> comes to the vacuum values? >>>> >>>> >>>> Best regards >>>> Jarek >>>> >>>> On Sun, 29 Dec 2019 at 22:45, Rob Thompson <[email protected]> >>>> wrote: >>>> >>>>> Have you synchronised the carbs to make sure the throttle butterflies >>>>> are tracking together with a full range of movement? >>>>> regards >>>>> Rob >>>>> >>>>> Rob Thompson >>>>> 0429 493 828 >>>>> >>>>> >>>>> >>>>> On Mon, Dec 30, 2019 at 6:05 AM Jarek Steliga <[email protected]> >>>>> wrote: >>>>> >>>>>> >>>>>> Ian, >>>>>> >>>>>> Thank you. I will definitely look at both plungers. >>>>>> >>>>>> Best regards >>>>>> Jarek >>>>>> >>>>>> On Thu, 26 Dec 2019 at 00:00, Ian Mc Phee <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> I go on colour (av gas for testing for colour), CHT (do all 4 >>>>>>> digitally) and maximum deviation is 8deg C but often ass low as 5 deg C >>>>>>> and EGT with a cheap dual analogue and it is of limited use. >>>>>>> >>>>>>> I seem to remember the bottom jet and needle controls fuel at 80% >>>>>>> power to full power and below that is the top jet controls fuel for >>>>>>> cruise >>>>>>> etc. >>>>>>> >>>>>>> I am more familiar with Bing's these days but the CD150 is similar. >>>>>>> 8 do know if there is any sucking of air inlet manifold it effects both >>>>>>> sides and not just the side of the leak. >>>>>>> >>>>>>> A bit of an aside but been having issues going onto full power on >>>>>>> take off and if done real slow over 15 seconds no issues. Do it over 5 >>>>>>> sec engine would not go full revs at first till you had just broken >>>>>>> ground. >>>>>>> I even added extra spring to bring it better to full throttle. Then >>>>>>> suggested to me as was not running rich it was a pin hole in diaphragm >>>>>>> but >>>>>>> was perfect BUT on second carb I noticed some scour marks on engine >>>>>>> side of >>>>>>> the plunger with the needle. I polished the aluminium first with emery >>>>>>> then worked up with 400, 600 and 1200 wet and dry. Totally fixed. >>>>>>> Plunger >>>>>>> was binding or sticking on its way up. So simple to fix. This has been >>>>>>> creeping up on me over 9 months. >>>>>>> >>>>>>> >>>>>>> Ian McPhee >>>>>>> +61 428847642 >>>>>>> Box 657 Byron Bay NSW 2481 Australia >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Thu, 26 Dec. 2019, 09:01 Jarek Steliga, <[email protected]> >>>>>>> wrote: >>>>>>> >>>>>>>> Hello Martin, >>>>>>>> >>>>>>>> I did the very opposite thing! Suspecting that it was the >>>>>>>> insufficient supply of fuel that caused the problem, I lifted the >>>>>>>> metereing >>>>>>>> needles all the way up from neutral (flush). This manoeuvre changed >>>>>>>> nothing >>>>>>>> except (predictably) making the plugs even blacker. The CHT behave >>>>>>>> normally. I am afraid the snag lies elsewhere, but many thanks for your >>>>>>>> suggestion. >>>>>>>> >>>>>>>> >>>>>>>> Regards >>>>>>>> Jarek >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Wed, 25 Dec 2019 at 22:30, Martyn Cook <[email protected]> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> Hi Jarek >>>>>>>>> >>>>>>>>> Maybe now that you have blocked the air leaks around the throttle >>>>>>>>> shaft the engine is running a little rich? That would certainly >>>>>>>>> reduce >>>>>>>>> your peak rpm. >>>>>>>>> >>>>>>>>> I have found getting the mixture correct on each side to be a bit >>>>>>>>> tricky. I adjusted the mixture on mine a bit at a time, watching the >>>>>>>>> degree of "blackness" on the spark plugs, plus the CHT behaviour. >>>>>>>>> But I >>>>>>>>> was taking it for a flight then adjusting when back on the ground. >>>>>>>>> >>>>>>>>> Maybe others know of a way to get the mixture setting correct on >>>>>>>>> the ground? >>>>>>>>> >>>>>>>>> Kindest regards >>>>>>>>> Martyn >>>>>>>>> >>>>>>>>> -- >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On 26/12/19 9:37 AM, Jarek Steliga wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Hello everyone, >>>>>>>>> >>>>>>>>> I have replaced the throttle shafts and the throttle plates. >>>>>>>>> Fortunately it looks like no rebushing will be necessary. The engine >>>>>>>>> became >>>>>>>>> far more stable now and responds precisely to throttle control inputs. >>>>>>>>> Clearly the badly worn out throttle shaft was (at least partly) where >>>>>>>>> the >>>>>>>>> shoe pinched. However, strangely enough, the engine will not rev up >>>>>>>>> beyond >>>>>>>>> static 2500 RPM. See the attached video. I am faced with yet another >>>>>>>>> conundrum. >>>>>>>>> max static RPM 2500.3gp >>>>>>>>> <https://drive.google.com/file/d/17rdy2gc83H4FCpMXqlTOlBn-KBV8kVJA/view?usp=drive_web> >>>>>>>>> Also the engine will not respond to throttle control beyond ca 4 >>>>>>>>> cm before the max power position. >>>>>>>>> >>>>>>>>> I am not sure if it's safe for me to attempt a take off as before >>>>>>>>> the throttle repair, the engine had reved up to static 2600 / 2700. >>>>>>>>> >>>>>>>>> I am looking forward to your thoughts. >>>>>>>>> >>>>>>>>> Best regards >>>>>>>>> Jarek >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>>
