What Ian says is true I believe. I do know the later version is nicer to fly. Earlier version wanted to snatch the control. Ian Mc Phee 0428847642 On 22/05/2015 1:03 PM, "Ian Williams" <[email protected]> wrote:
> > > Hi Michael, > > > > Thanks for your reply. I still think NZ is not too bad, though not so > much of it. > > > > I thought a quick response was necessary based on my thoughts about your > friends aileron issue. However I will also try and get you up to speed > with the aileron changes. > > > > I am the engineer for 2 Dimona’s and 2 Grob 109’s here in NZ. One Dimona > (ZK-GCB) is ex Thai Air Force which I have “restored” over a 5 year > period. During that time I have had a lot of help and good advice from > Nigel Baker Ian McPhee Laurie Hoffman, Rob Thompson and John Callaghan … > all fine upstanding Australians. If I have made any errors in this > discussion I am sure it will be corrected. > > > > The difference between the systems is that if you consider there is a load > pushing both ailerons up, the aileron push rods are in compression (old > system) and in tension (the later system). The old system uses 5 bearing > sets in each wing and the new one only 3. They can be clearly checked which > is which because the outer aileron bell crank of the old system is made > from tube steel while the later one is made from flat steel. I have some > photos I can send to you showing the difference. > > > > As I indicated, the ailerons on GCB lift about 20mm or so at 100Kts. If > you attempt to duplicate that on the ground manually, the load you have to > put into the aileron to lift 20mm is VERY high. That indicates the up load > in flight is also very high. So it is a logical improvement to change the > aileron push rod to a tension mode). Even with the 5 bearings, there is > still enough up force from the ailerons to bend the aileron push rod > between bearings. (where the 20mm lift comes from). Nigel indicated It is > not a practical idea to modify the aileron circuit of the older Dimona’s. > > > > On GCB I also found all 10 (3 bearing) bearing sets inside the wing were > seized. Because the ball bearings used at the time had their entire outer > ballrace made from nylon. Maybe OK short term but as you may know, nylon > does tend to absorb water and slightly expands…. Hence seizing all the > bearings. They are not easy to replace as 5 large holes need to be made > under the wing and their associated repair schemes, however can be done. > Diamond supplied the new bearing sets which were a complete steel bearing > but with a nylon “tire” in the outer edge. A much better system and the > same as used on the Diamond DA 40 elevator rod. > > > > Re your friends Dimona, An issue like that would set off a big alarm. > There could be a few issues. Some Dimona’s didn’t have any push rod > bearings at all .. just bushes so if there was any radial play that could > cause a problem. Also the bearing sets were mounted in plywood brackets > butt glued to the inside skin … not really that strong. I am thinking that > maybe one or more of these wooden brackets has come off. Also based on my > above comments regarding the high flight loads put back thru the aileron > circuit in flight, maybe you should make a closer inspection (try using a > USB enderscope). Also note that the older aileron push rod has a joint > about 5 feet or so into the wing from the root rib. This can make things a > bit confusing as well. > > > > I will put together some photos for you .. .also will show the holes we > made to replace the old bearings and also of the new and old bearing sets. > Is there anything else you would like a picture of. > > > > Best regards > > > > Ian WIlliams > > > > > > > > > > > > > > > > > > > > > > *From:* [email protected] [mailto:[email protected]] *On > Behalf Of *Michael Stockhill > *Sent:* Friday, 22 May 2015 12:59 a.m. > *To:* [email protected] > *Subject:* Re: [DOG mailing list] Engine mount for Limbach > > > > Ian Williams > > > > I follow DOG from Montana, one of the prettiest of the Great Satan's 50 > states. I own an H-36, SN 3518, and maintain another for a friend. > > > > I read your post discussing a modified aileron actuation mechanism. I am > not familiar with that, so wonder if you could enlighten me? > > > > My friend's H-36 has an odd characteristic--at the onset of any > disturbance or turbulence, the ailerons oscillate. I'd call it aileron > snatch, but it doesn't quite fit the formal definition for the phenomenon. > I'm headed his way in the next couple days to check the rigging; last time > I was there, we checked and there is no play in the system. His bird is > very tail heavy for some reason, so its CG is very near the aft range. > This may or may not be relevant. > > > > Best, > > > > Michael Stockhill > > > > On Thu, May 21, 2015 at 5:14 AM, Ian Mc Phee <[email protected]> wrote: > > Interseting your observation about the tilt of the engine and may explain > something. Ours points up for some unknown reason but is goes so well. We > have bing carb and I had to finally fit different jets in each carb to even > up temeratures (one 2.05mm and other 1.90mm). Bings only adj is jets. > > > > Ian McPhee > > > > Ian McPhee > > > > > > > > On 18 May 2015 at 09:29, Ian Williams <[email protected]> wrote: > > Hi All, > > > > Interesting reading. Nigel … rip into it, I am looking forward to > seeing the finished HK36. > > Regarding the engine mount for the H36, One thing I have noticed, looking > at all the pics of Dimona’s available on the internet is the thrust line of > the earlier H36’s seems to be different as compared with the later ones … > I mean that if the prop is vertical and you are looking at it from the > side, the prop angle looks as if it is at the wrong angle ref the fuse … it > pointing “up” The later H36’s seem to have a lower “angle “ relative to > the fuse. (Havn’t explained it that well but you should understand). Our > H36 is an earlier one (S/no 3537) We have 2 alloy spacers on the rear > mounts which decrease the angle a bit which I assume is the same for all > the ex Thai Dimona’s. Later h36’S seem to have a lower angle. > > Of interest, we have just done 100hrs in GCB since its first flight in > June last year. It is a great little rocket and by far has exceeded our > expectations. It has the original aileron control configuration but a new > set of bearings in the wings (5 sets per wing) A mission to replace but > works well. It is different in that the control forces than the later ones > … the stick is quite “firm” around the centre for a small lateral control > input but max aileron control load at speed is actually significantly less > than a Grob 109 which I am involved with. It does take a little to get > used to but is quite OK. With the new bearings there is no “sticking” at > all. When cruising at 90 kts or more, the ailerons do lift up about 15mm > or more. However both are even. Looking at the wing section and the > pressure distribution under the ailerons it is quite clear that the > compressive load into the aileron push rods is very high so the modified > configuration was a logical one. > > We have had 2 problems … the first was a fuel blockage where there was > some crap in the banjo bolt at the bottom of the fuel tank which was > impossible to see (looked like grey cotton wool) .. ie between the finger > strainer and the 3 outlet holes of the fitting … not helped by using some > CRC rubber for a small sealing job on the tank (learn’t a real lesson > there) However all replaced, flushed out and OK. > > The other issue is at lower RPM and lower airspeed the prop tends to slip > into fine pitch. Not a major problem as in cruise mode it is OK. > > Other interesting things are > > · I have installed an MGL fuel computer using the original VDO > float and a new turbine type flow sensor … a great system as you know > exactly how much fuel is available and it also removes the non linearity of > the fuel tank contents (5 calibration points) > > · The engine indicates an oil temp around 65 to 80 degrees C > cruising. RHS rear cyl drops to about 120degrees C and the LHS side around > 160. I think the variation is caused by a slightly different mixture > setting of the carbs. Take off cyl hd temps around 190 (depending on the > OAT) > > · I have installed a 5 V regulator supplying power to a small GPS > plus a couple of USB sockets to keep ipads etc charged (note if using USB > sockets the 2 * signal pins need a specific bias voltage to enable apple > products to accept a charge … tricky people those apple dudes. > > · I also connected the comm. Radio audio amplifier to double as > the Intercom amplifier with a panel switch that turns it on or off. Very > simple and works real well. Combined also with a MP3 socket so ad you are > cruising along, you can play music from your iphone thru the headsets. A > real spin off also is if someone calls you the ringing and audio from the > iphone is directed thru the intercom so no problem hearing the person > calling. > > > > So all good. If any of you happen to come to New Zealand I would love > both to see you and can provide some accommodation if required. I think > Wolf Hoffman did a great job all those years ago. > > > > Best regards > > > > Ian Williams > > ZK-GCB > > > > > > *From:* [email protected] [mailto:[email protected]] *On > Behalf Of *Ian Mc Phee > *Sent:* Saturday, 16 May 2015 10:53 p.m. > *To:* Laurie Hoffman; DOG LIST > *Subject:* Re: [DOG mailing list] Engine mount for Limbach > > > > I will take photos tomorrow but it is a great (brilliant) mod & you must > have it in a L2400 to gain access to oil filter. Engine in and out is a > piece of cake especially when you remove front engine mounts AND the front > Truss (2 bolts). Engine goes in and out with muffler exhaust all attached > to engine. So easy. > > Im > > On 16/05/2015 7:29 AM, "Laurie Hoffman via dog" < > [email protected]> wrote: > > Hi Ian, > > Re removable front cowl panel. > > Did you find the template that you had? > > *Regards* > > *Laurie Hoffman* > > > > > > > > > ------------------------------ > > *From:* Ian Mc Phee <[email protected]> > *To:* DOG LIST <[email protected]> > *Sent:* Saturday, 16 May 2015, 7:21 > *Subject:* Re: [DOG mailing list] Engine mount for Limbach > > > > They are VW part & will check old box later for number or may have it > written up in logbook. Front ones need drilling and cutting. Back is as is > ready to use. Do you have the removable panel at front? Great mod. > Ian Mc Phee > 0428847642 > Box 657 Byron Bay NSW 2481 > AUSTRALIA > > Ian m > > > > On 16/05/2015 5:27 AM, "Angel Jimenez Martin" <[email protected]> > wrote: > > Hello everyone, > > Could someone tell me if it has the same engine mounts Limbach flock of > Dimona and Dimona Mk 2. > > Greeting > > > > > > >
