It is also worth mentioning that the tachometers are to be tested and placarded. Whatever the reason, my tach is placarded as indicating 80 rpm low.
I have had instances of being at full throttle in cruise at high altitude with either mountain wave or other extensive sink where indicated rpm drops into the range we are discussing. In those instances where it persists, I have tried to maintain altitude raising hell with cruising speed On Mon, Oct 22, 2018, 2:35 PM Jarek Steliga <[email protected]> wrote: > Michael, > > When I wrote 'prolonged flight situation', I guess what I was trying to > say was: falling faul of that > *CAUTION *Avoid RPM during cruise below 2300 min –1! found in Dimona > Flight Manual. > > I will keep in mind what you said about windmill-starting the engine. > > Regards > Jarek > > pon., 22 paź 2018 o 21:34 Michael Stockhill <[email protected]> napisał(a): > >> I am not sure what the definition of prolonged operation might be. In my >> soaring environment, thermals are generally strong,showing 5 to 8 knots, >> but they are quite far apart. I frequently need a relight, and I sometimes >> dodder along with the prop in cruise pitch at what I sense is zero >> thrust--somewhere around 1500 to 1800 rpm. I would be surprised if this >> translates to more than 15-20% of available power. That may be the least of >> my concerns when I break the surly bonds. >> >> But the recent FAA AD note on Hoffman wood props brings up another >> potential concern. I now realize that with lag screws holding the blades to >> the hub, overspeeding could potentially lead to shedding a blade due to >> high centrifugal force. I have occasionally windmill-started the engine by >> diving to accelerate to 70 knots or so. (Once for real when a wire on the >> starter came free due to using spade connectors rather than real aircraft >> design.) After the engine starts the rpm really wraps up. Recovery must be >> aggressive to keep from overspeeding. Something to watch in the future. >> >> On Mon, Oct 22, 2018, 1:07 PM Jarek Steliga <[email protected]> >> wrote: >> >>> Nick and Nigel, >>> >>> I am suddenly wondering how relevant these considerations are to your >>> average, daily flying. In other words why would anybody fly their Dimona at >>> RPMs below 2300? As I experienced it myself in my first tentative flights, >>> you want to maintain your RPM at 2300 or more for cruise, to keep the IAS >>> at somewhere around 130 km/h. If on the other hand you want to circle in >>> thermals which are too weak for soaring, then you set the propeller to >>> START pitch and also maintain 2300 RPM to keep the IAS near 100 km/h (and >>> the sink rate at zero to utilize even the weakest updrafts). Other than >>> that you just idle the engine for 2 minutes or so prior to switching it >>> off. >>> >>> Could you please shine light on what I am missing? Can you think of >>> prolonged flight situations when you would like the propeller to turn at a >>> slower rate? >>> >>> >>> Regards >>> Jarek >>> >>> pon., 22 paź 2018 o 15:22 Nigel Baker <[email protected]> >>> napisał(a): >>> >>>> Idle power is not the problem. >>>> >>>> The harmonic happens under load. It is influenced by the acceleration >>>> of the crankshaft every time the engine fires. Low power = low acceleration >>>> levels. >>>> >>>> Looking for more info but from memory it was a band of 200RPM. >>>> >>>> Yes it is important to use a prop known to match the engine re >>>> harmonics thus you will find a list of props approved for the Limbach >>>> Engines under its Type Certificate. >>>> >>>> Note this is also true of the aircraft manufacturer as well. Type >>>> certification must match between the engine the aircraft and the prop. >>>> >>>> The harmonics are completely different to prop balance which is another >>>> complete issue. >>>> >>>> I once asked Peter Limbach how could it be possible to operate at full >>>> power at 2100-2300 RPM. I get more than that static on ground test. >>>> >>>> Ah but we found an issue on the Dyno which sort of implies a different >>>> issue again. >>>> >>>> Nige. >>>> >>>> >>>> >>>> >>>> >>>> *From:* [email protected] <[email protected]> *On >>>> Behalf Of *Ric Sutton >>>> *Sent:* Monday, October 22, 2018 10:39 PM >>>> *To:* [email protected] >>>> *Subject:* RE: [DOG mailing list] Zenith 150 CD 3 - oil >>>> >>>> >>>> >>>> Sorry Nige, it was my imaginary lower limit to the range of revs that a >>>> bad harmonic was present, Not the lower limit of operational revs. though i >>>> guess why does the lower rev range of a bad harmonic matter if you are to >>>> avoid prolonged operation below 2300. This being the case what is the >>>> official standpoint of limbach on thermalling with the engine ticking over >>>> below this 2300 limit? >>>> >>>> Cheers >>>> >>>> Ric >>>> >>>> >>>> >>>> *From:* [email protected] [mailto:[email protected] >>>> <[email protected]>] *On Behalf Of *Nigel Baker >>>> *Sent:* Monday, 22 October 2018 2:54 PM >>>> *To:* [email protected] >>>> *Subject:* RE: [DOG mailing list] Zenith 150 CD 3 - oil >>>> >>>> >>>> >>>> You have seen it Rick and not at the pub over a beer.. >>>> >>>> Look in brackets below. >>>> >>>> 2300RPM >>>> >>>> Nige. >>>> >>>> >>>> >>>> 9 >>>> >>>> >>>> >>>> Hoffmann >>>> 2 >>>> H 36 >>>> DIMONA >>>> Limitations >>>> >>>> >>>> >>>> >>>> >>>> 2.4 *Engine Limitations* >>>> >>>> >>>> >>>> Engine >>>> Type: Limbach >>>> L 2000 EB 1C >>>> >>>> >>>> >>>> RPM Limitations >>>> (Indicator Markings) >>>> >>>> >>>> >>>> Maximum take off RPM >>>> (maximum 5 minutes) 59 KW (So hp.) 3,400 RPM >>>> >>>> >>>> >>>> Maximum ambient atmospheric temperature + 380 C (+100 F) >>>> >>>> >>>> >>>> Maximum RPM (METO) 53 KW (72 >>>> hp.) 3,000 RPM >>>> >>>> >>>> >>>> Red Line >>>> 3,400 >>>> RPM >>>> >>>> >>>> >>>> Caution Range - >>>> Yellow Arc 3,000 – >>>> 3,400 RPM >>>> >>>> >>>> >>>> Operating RPM - >>>> Green Arc 700 – 3,000 RPM >>>> >>>> >>>> >>>> *CAUTION* >>>> >>>> >>>> >>>> Avoid RPM during cruise below 2300 min –1! >>>> >>>> >>>> >>>> >>>> >>>> 2.5 *Oil Pressure:* >>>> >>>> >>>> >>>> Maximum Oil Pressure (red line) 4 bar (55.8 psi) >>>> >>>> >>>> >>>> Minimum Oil Pressure (red line) 1 bar (13.9 psi) >>>> >>>> >>>> >>>> Operating Range (green arc) 1 - 4 bar (13.9 — 55.8 psi) >>>> >>>> >>>> >>>> 2.6 *Oil Temperature*: >>>> >>>> >>>> >>>> Maximum Oil Temperature (red line) 120 C (248 F) >>>> >>>> >>>> >>>> Operating Range (green arc) 50 - 120 C (122 — >>>> 248 F) >>>> >>>> >>>> >>>> Minimum Temperature (red line) 50 C (122 F) >>>> >>>> >>>> >>>> 2.7 *Cylinder Head Temperature:* >>>> >>>> >>>> >>>> Maximum Cylinder head temperature (red line) 250 C. (482 F) >>>> >>>> >>>> >>>> >>>> >>>> 2.8 *Voltmete*r: >>>> >>>> >>>> >>>> Maximum voltage with engine running: (red line) 14 VDC >>>> >>>> >>>> >>>> 2—3 >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> *From:* [email protected] <[email protected]> *On >>>> Behalf Of *Ric Sutton >>>> *Sent:* Monday, October 22, 2018 4:39 PM >>>> *To:* [email protected] >>>> *Subject:* RE: [DOG mailing list] Zenith 150 CD 3 - oil >>>> >>>> >>>> >>>> Hi Jarek >>>> >>>> I’m sorry but i have had a look and can’t seem to find a reference to >>>> my second imaginary number. I don’t know whether it was obtained through >>>> conversations with Hoffman people or limbach people or dimona people or >>>> people from a random encounter at a pub. It may have been obtained from >>>> what felt about right ie. the bottle of beer in my cup holder didn’t froth >>>> over or go prematurely flat below those revs( just kidding, though if >>>> anybody here has a clever idea on where and how to mount a cup holder that >>>> would be great). All jokes aside i do recall a conversation with a >>>> propeller service agent that told me of an aluminium based air frame that >>>> was financially written off after cracks were found due to the bad >>>> harmonics of an “alternate” propeller so from that i took it as being a >>>> serious thing. i also found some you tube videos of propeller blades self >>>> destructing.( propeller resonance >>>> <https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=video&cd=1&cad=rja&uact=8&ved=0ahUKEwiLtIzSsJneAhVLMI8KHY8YAUEQtwIIJzAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DPQjmDmcWJn8&usg=AOvVaw048W5y_0kGNdO0WaB0eUdi> >>>> ) >>>> >>>> What you have done now though is inspired me to finish my home made >>>> accelerometer/balancer and gather some actual real data to see if i can >>>> establish some numbers for my own curiosity J >>>> >>>> Welcome aboard and may you enjoy your dimona as much as many of us do >>>> >>>> Cheers >>>> >>>> Ric >>>> >>>> >>>> >>>> >>>> >>>> *From:* [email protected] [mailto:[email protected] >>>> <[email protected]>] *On Behalf Of *Jarek Steliga >>>> *Sent:* Friday, 19 October 2018 3:31 AM >>>> *To:* [email protected] >>>> *Subject:* Re: [DOG mailing list] Zenith 150 CD 3 - oil >>>> >>>> >>>> >>>> Michael, Ric thank you. >>>> >>>> >>>> >>>> >>>> >>>> Ric, where did you find the "range" of unrecommended RPMs as opposed to >>>> just a lower limit of 2300? I leafed through both attached documents and >>>> didn't come accross the second number. I also tried to google "Limbach L >>>> 2000 harmonics" and got nothing. If it isn't harmonics (wchich I hope it >>>> isn't) then the RPMs lower limit would suggest excessive load torque with >>>> prop in just the cruise position. >>>> >>>> >>>> >>>> Regards >>>> >>>> Jarek >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> Regards >>>> >>>> Jarek >>>> >>>> >>>> >>>> czw., 18 paź 2018 o 15:53 Michael Stockhill <[email protected]> >>>> napisał(a): >>>> >>>> In the States, dashpot oil is readily available from vintage British >>>> car parts suppliers such as Moss Motors for $10-12 for a squeeze bottle. >>>> Claimed to have appropriate preservatives and conditioners. As little as is >>>> consumed, I have found no incentive to look for alternatives. >>>> >>>> >>>> >>>> On Thu, Oct 18, 2018, 5:09 AM Ric Sutton <[email protected]> >>>> wrote: >>>> >>>> Hi Jarek >>>> >>>> Here’s my two cents worth- i use automatic transmission/power steering >>>> fluid in my cd150’s. seems to work fine and haven’t had any compatibility >>>> issues with rubber diaphragms etc as yet. The oil and plunger act as a >>>> damper for the piston to which the needle that alters your fuel air mixture >>>> is attached. Over the years i have heard various stories from people that >>>> use these carbies n race cars that actually snip the damper off(similarly >>>> people that don’t put any oil in there), to stories from people that use >>>> them in multi carb set ups (ie 12 cylinder jaguar engines) that can’t get >>>> them to tune properly without the correct oil (though after some discussion >>>> i believe that spindle wear was more their issue). In an automotive >>>> situation there will be some minor noticeable throttle response differences >>>> but in the dimona application i suspect the differences will be minimal >>>> particularly as instantaneous dramatic throttle changes should be rare. >>>> >>>> The rev issue >>>> >>>> The reason the book states that *prolonged* operation in that rev >>>> range is to be avoided during cruise is indeed because of a bad harmonic >>>> (potential for cracked crankshafts etc) Thus, i believe that it is a >>>> problem whether the blades are in fine or course pitch it is just operating >>>> in that rev range with a moderate load on. In saying that, these are a >>>> reasonably robust little engine, don’t be scared. Note the emphasis on the >>>> word prolonged. >>>> >>>> Please someone jump in if they have info to the contrary this is just >>>> what i have learnt over the years and am always willing to learn something >>>> new. >>>> >>>> >>>> >>>> *From:* [email protected] [mailto:[email protected]] *On >>>> Behalf Of *Jarek Steliga >>>> *Sent:* Thursday, 18 October 2018 5:47 PM >>>> *To:* [email protected] >>>> *Subject:* Re: [DOG mailing list] Zenith 150 CD 3 - oil >>>> >>>> >>>> >>>> Hello again, >>>> >>>> >>>> >>>> If my oil "mixture" is too thick (or too thin) what are the symptoms? >>>> Does the carburator respond with a delay or too fast to the throttle >>>> inputs? Is that dangerous or just annoying and easily noticed? >>>> >>>> >>>> >>>> >>>> >>>> Regards >>>> >>>> Jarek >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> czw., 18 paź 2018 o 08:43 Jarek Steliga <[email protected]> >>>> napisał(a): >>>> >>>> Thank you >>>> >>>> >>>> >>>> śr., 17 paź 2018 o 23:28 Rob Thompson <[email protected]> >>>> napisał(a): >>>> >>>> Part number 10 on the diagram. >>>> >>>> regards >>>> >>>> Rob >>>> >>>> >>>> >>>> Rob Thompson >>>> >>>> 0429 493 828 >>>> >>>> (Please note that my new email address is [email protected]) >>>> >>>> >>>> >>>> >>>> >>>> On Thu, Oct 18, 2018 at 7:50 AM Jarek Steliga <[email protected]> >>>> wrote: >>>> >>>> >>>> >>>> >>>> >>>> Hello Rob, >>>> >>>> >>>> >>>> >>>> >>>> The oil seems to disappear too fast as you say. Could you help me to >>>> identify which particular o-ring on the attached drawing needs to be >>>> replaced? >>>> >>>> >>>> >>>> When you mention 5/xx multigrade, do you mean 5W/xx? >>>> >>>> >>>> >>>> >>>> >>>> Best regards >>>> >>>> Jarek >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> ---------- Forwarded message --------- >>>> >>>> From: *Rob Thompson* <[email protected]> >>>> >>>> Date: wt., 16 paź 2018 o 22:23 >>>> >>>> Subject: Re: [DOG mailing list] Zenith 150 CD 3 - oil >>>> >>>> To: <[email protected]> >>>> >>>> >>>> >>>> >>>> >>>> Hi again Jarek, >>>> >>>> You can use straight engine oil but even a 5/xx multigrade is a bit >>>> thick and tends to dampen the piston too much. >>>> >>>> We mix 50/50 light machine oil and engine oil. >>>> >>>> If it keeps disappearing it means that the rubber O-ring which seals >>>> the needle inside the piston is perished. >>>> >>>> regards >>>> >>>> Rob >>>> >>>> >>>> >>>> Rob Thompson >>>> >>>> 0429 493 828 >>>> >>>> (Please note that my new email address is [email protected]) >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> Hello, >>>> >>>> >>>> >>>> As per Limbach Maintenance Instruction, only a specific oil p / n: >>>> 170.210.005 can be used to fill up the carburator. Since this seems to me >>>> pretty pricey, can other, readily available oils be used in its place? What >>>> is its recommended viscosity? >>>> >>>> >>>> >>>> Best regards >>>> >>>> Jarek >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> --------------------------------------------------------------------- >>>> You are subscribed to the Dimona Owners Group mailing list. >>>> To unsubscribe, send email to: [email protected] >>>> >>>>
