xair1159

And what about the airframe you hid round the side of the garage? No secrets on Google Earth!

All borrowed from http://www.faceless.co.za/ Try this one http://www.faceless.co.za/read_fl.asp?pass_num=41

Oscar, A well reasoned post and I would agree with much of it. However you base it on the fact that Jabiru are local and easily contacted, which is certainly not the case here in Europe. I used a Jabiru 2200 hyd tappet engine for several years which was fairly reliable but sadly lacking in power. Attempts to contact the factory with any queries were a waste of time and the local dealer is expensive and doesn't have a great reputation for customer relations. I would guess that now Camit are setting up as an alternative source they could be easier to deal with, but the Jab engine could yet become an orphan over here. The warranty was basically worthless with any and all problems blamed on the owner, installation, maintenance, the way it was flown, the fuel - anything but poor design or quality control. Given the above you can see why this side of the world D-Motor is more attractive, plus I have visited the factory and was convinced it is a solid business and the guys are in it for the long haul. I was impressed enough to buy one to replace the Jab 2200 and have 33 hours on it so far with zero oil use between changes, found it surprisingly easy to cool and with a lot more power. Early days in terms of meaningful TBO etc. but I am quietly confident as they say! Nick

D-Motor #14 is up and running in an Xair Hawk (H, Hanuman) with around 5 hrs flown so far. Definitely more power than the Jab 2200 it replaced, smooth and good T's & P's in some fairly warm weather for this end of the world. Installed weight of 60kg wet and ready to run, this was the first "production" installation and could be reduced by 1 or 2 kg with experience gained. The Jab would just drive a 60x40 prop, this is currently using a 60x46. Fuel burn typically 10-13 L/h at sensible speeds, 22-23 L/h flat out, which is around 95 kts in the Hawk, but there is still a bit more to come with a slightly revised prop. It also sounds great! The 6 cylinder is running on the factory dyno with good results so far and apparently it sounds even better. Nick

With a nominal 80hp Jabiru 2200 the UK Xair Hawk used a 60 diam x 40 pitch narrow chord prop. It is believed that actual engine output was probably closer to 70 something hp, and across several aircraft, not just one. Current testing on the D-Motor Hawk (92 hp typical on the dyno) shows optimum performance is given by a 58 or 60 diameter x 46 inch pitch. Strangely the best takeoff / climb / cruise mix is given by the smaller 58" diam prop, the reverse of common wisdom of "swing a big prop slowly". You can certainly fly out of 250M strips with a good margin and no worries. The Jab maxes at 3300 and D-Motor at 3100, not a lot different. Comparing the same cruise band of say 2400-2600 between the two, the Jab would give 80kts at 2500, the D-Motor closer to 90kts with better fuel burn thanks to the EFI. On their website there is now a D-Motor agent listed for Australia.

I carried out the structural testing of the Xair Hawk (H/Hanuman elswhere) for the UK section S approval and I fly one. You would be surprised at the loads an apparently simple bolted tube airframe can actually handle. They are also easily repairable unlike welded tube or composite airframes. Some checks you can carry out to compare the two:- If you get a chance, have a look at both airframes in the nude with no covers. Check out the way the various tube ends are terminated and bolted. Grab hold the prop (near the spinner of course!) and try to move it sideways. Push and pull on the horizontal tail planes and look at the fabric on top the fuselage. You should notice distinct differences between the two aircraft. A personal opinion - the Skyranger does exactly what it says on the tin, but the Xair is a stronger build which will handle turbulence better. Ref comments above, the Xair undercarriage is very robust and will handle "firm" arrivals with no problems. It will also take a lot more than 80 hp, I have flown 912 and D-Motor versions with 90+ hp and they were both very good, the D-Motor being even better due to the much lighter installation. Nick EI-ECK

The engine is certainly lighter than the Jab and the bare unit can be easily lifted onto a bench. It is quite a bit narrower due to the lack of rocker gear, but engine mount to prop flange is identical. Top of the block to bottom of the silencer is similar because of the (well designed !) inlet manifold and fuel injector assembly. I am going for a front mounted radiator similar to the Viking setup, so the cowling can be tapered towards the front but needs some depth to accomodate the rad.

Not only news updates but 20 plus deliveries as well with more to come. My engine is sitting on the bench waiting to start installation and the Jabiru is now out the aircraft and for sale. The web site was deliberately kept low key until there were engines available for delivery, so I would expect more regular updates from now on. The 6 cyclinder should run before Friedrichshafen and both engines will be shown, plus those in the BOT Sportcruiser aircraft and others. The BOT is a well sorted and tidy installation by some good engineers. Nick

Don't know if any of you have seen bexrbetter in disguise lately, but seriously, I was told by someone on a stand at the 2012 Oshkosh that Chinese business characters were going round trying to buy various items for cash on the spot - even complete engines. I imagine a bit of reverse engineering was planned using ultra high high quality Fosters tinnies?

Interesting to read the theories on plug placement from nev and bex which make sense, but I reckon most small a/c engines are the same layout. I can see the inlet plug getting wet from the incoming mixture, but isn't the best position determined by the mixture flow and turbulence from any squish areas when both valves are closed and aiming for an ideal burn? Does knock or detonation come into this as well? Yes, the plugs are both the same heat range as they are in Jabiru, Rotax and Verner, the only other twin plug engines I have experience on. Would you suggest hotter plugs by the inlet? I will ask if I can post a photo of the insides and see if you can spot one of the design tricks. I guess I should have known better about the last line! You are probably aware that many bankers and property gangsters over here quite deliberately sold faulty products.

Ain't it great to start a good discussion! Some interesting and apparently well informed comments from a couple of people though. To try and answer some of the points in no particular order:- My "10 minute flight" was 2 hours as P1 on the production version and another 3 or 4 hours as P2 on a couple of previous versions. They did try various head and piston configurations, I was shown a number of them in the scrap bin. Different plug and valve positions were tried, again some samples were in the bin. I believe they found moving the plugs even a small amount made a significant difference. Different types and makes of plugs were tried before settling on one used by Mercedes which gave a small but repeatable hp gain. Exhaust valves are sodium filled to help with heat removal, inlets are usual style. Fuel burn - I have an MGL Xtreme with fuel flow and cruise my Jab 2200 at 2500-2600 which gives me a genuine 80kts. Fuel burn is 13L/hr at 2500 up to 14 L/hr at 2600. I will try and get hold of similar accurate figures for the D-Motor, but from my flight I would guess at 11-12 L/hr for the same cruise speed. One thing I did notice was that a well used engine that had been stripped for checking had remarkably clean heads and pistons. My Jab required a head job at 350 hrs due to rough running and failed hyd tappets and it was well coked up with burnt oil and from running rich on the factory supplied jetting. Perhaps EFI and valve stem seals have something to do with this?. There are some tweaks which to my knowledge were never used on old flat head engines. (Showing my age, my first wreck of a car was a flattie). Why not use Subaru type auto conversions - most are heavy. Having said that, the Viking looks interesting, but it is still heavy, which is a problem with a 450kg limit, plus possible CG problems. Cost of spares / Nikasil - not knocking them, but as a Jabiru user, will these be any different to constant changes being made, many of which are not retro fit? Thin fin heads, different size and location for through bolts, hyd tappets, roller tappets, various cams etc. Any small volume manufacturer will have the same problem. Time will tell. With the supplied silencer it is not loud (we have to pass noise tests here for certification) but the usual comment is that it does sound more like a "proper" a/c engine. I would imagine D-Motor have ended up with the best compromise between power, fuel, heat, efficiency, cost etc. etc. Aren't most designs of almost anything a compromise unless you have unlimited budgets and time? No one in their right mind is going to knowingly sell a poor design.

I recently visited the D-Motor factory in Belgium and the huge investment they have made in CNC machines, dyno, flow bench and other plant shows these guys are serious about making a good product. The side valve/flathead may be old style, but its high, flat torque curve is ideal for a direct drive, low rpm aircraft engine. The original flathead complaint of poor breathing isn't really a problem at 3000 rpm. They have spent several years developing the engine and it has some very clever and subtle design tweaks - many modern techniques like flow visualisation weren't around when the original design went out of fashion. I fly an aircraft fitted with a 2200 Jabiru and have also flown the identical airframe with the D-Motor. My Jab is a mid range hyd tappet version with a claimed 80hp and has been reliable but sadly lacking in power, so there is a huge jump in performance with the D-Motor thanks to a demonstrated 91+ hp. Comparing the published Jabiru curves with a D-Motor dyno printout shows roughly 10hp more at all revs from 2200 to 3000. I have a feeling that in real life with the hyd tappet engines this is probably nearer to 15hp more. My Jab 2200 installation weighed 68kg (I weighed all the major lumps) the D-Motor is at least 10kg less at 56-57 kg, both wet and ready to fly. Ref the comments about efficiency and fuel burn, the D-Motor is actually better than the Jabiru thanks to the full EFIand the fact you are not running a carby excessively rich to try and cool the valves. If a valve fails or sticks in the Jabiru (not uncommon) one way or another it meets the piston, the engine is toast and you have a problem. Should the same happen in a flathead you just continue to run on 3 cylinders which should get you safely on the ground. The first 25 engines are being delivered now. Yes, it is early days and hours have to be accumulated to demonstrate long term reliabilty, but I am impressed with the engine. Might be a s/h Jab 2200 for sale shortly.

Despite living on the other side of the world, I sourced my replacement pump from an online car parts shop in Australia. Even with carriage costs it was still half the price of our local dealer! The Jabiru fuel pump is a Goss 875 (BCD 1875) which fits the Peugeot 404, 504 and 505 up to 1979. Jabiru have modified it somewhat. The spring is lighter and the plunger shorter to reduce the pressure to suit the Bing, but these can be swapped over and the main parts likely to give trouble are the diaphragm and valves. The fuel-in spigot is the same but the fuel-out is vertical, not the 90deg to horizontal type, so the answer is swap the top covers. The vent in the nylon spacer, between the two diaphragms, is just a hole and has no small hose nipple. Again, the answer is to transfer the other one, or insert a suitable fitting. It was about this point I discovered the trick in my post above.

Might have said it on here before, but when you rebuild the Jab mechanical pump fit the 6 (8?) screws holding the two halves finger tight at first. Then fully flex the diaphragm by pushing the operating lever right in and only then fully tighten the screws. To quote the original article I read, "failure to do this will result in high and erratic fuel pressure". They are dead right as I found out the hard way. The screws only need to be tightened firmly, not until they squeak as this will only crush the diaphragm edge and damage it. Fuel pressure is set by the spring strength and if the diaphragm isn't flexed, the load from stretching it gets added to the spring, plus it will also shorten the life of the new diaphragm.

It's not just the modern management tech, although that will give optimum performance, but thanks to modern methods like CAD and flow simulation it has some very subtle design features which give surprising performance. The side valve (flathead) design gave a flat torque curve at modest rpm, but the 180 degree airflow route into and out of the cylinders caused poor "breathing" at higher rpm. Not a problem for 3000rpm or so of a direct drive and the flat torque is ideal. Even less moving parts in the valve train and mechanically adjusted tappets, not hydraulic ones, plus it is very compact due to the lack of rocker gear. The prototypes have done several hundred hours each in a variety of airframes, but it now needs service hours to get some credibility. Yes, I have one on order.

The initial production batch of 25 D-Motor LF27 engines are being delivered over the next month or so. The D-Motor is currently being rated as 90bhp at 3100 rpm. All engines are run on a dyno before delivery and the first few have given around 93bhp. The dry, bare engine weight is 46kg and the installed ready to run weight should typically be 56-58kg. Compare this to my own Jabiru 2200 where I weighed most of the major lumps and came up with an installed weight of 68kg for a quoted output of 80bhp at 3300rpm. The Jab has been reliable but disappointing in terms of power, although a top end and hyd tappet job at 350 hrs (1000hrs TBO?) did improve it a little. I have flown an identical airframe to my own fitted with a D-Motor and with 10kg less up front and at least 10hp more there was a major improvement in performance for similar or better fuel burn. With luck I should be able to post some up to date photos and more details shortly. Nick

Try this link; http://www.vintagewings.ca/VintageNews/Stories/tabid/116/articleType/ArticleView/articleId/325/language/en-CA/Lower-than-a-Snakes-Belly-in-a-Wagon-Rut.aspx Bit long but www.vintagewings.ca and the article is titled Lower-than-a-Snakes-Belly-in-a-Wagon-Rut Some real low flying!

"It looks like a Skyranger-ski to me." Nah, deffnitly an Xair H (or Hawk / Hanuman depending which bit of the world you are in) Got one just like it. If it is the Jab 2200 version could that have anything to do with the choice of landing site?

For a more affordable dynamic balancer, have a look at this from Smart Avionics: http://www.smartavionics.com/prod-pb.html I have used a PB1 successfully for some years now. Would like to update to the PB3 which looks easier to set up with Bluetooth instead of hard wired and a better display. Hard to justify when the one I have is working perfectly and gives good results.

I know there are various inlet manifold fixes to improve mixture distribution for the 3300 engine, but is there anything similar for the 2200? Cylinders 3 & 4 on my engine have EGT's that vary a lot at different rpm's. Tilting the carb to one side or the other may even things out at one point, but then makes it worse elsewhere. To me this suggests that the fuel mix is going one side or the other of the splitter in the manifold, so has anyone tried removing it or changing the shape? I'd be interested to hear of any good ideas. Nick

I think it's generally accepted that the hyd engines are not performing as well as the old solid ones and Jab have had various combinations of high and low leak tappets and cams to try and improve things. Based on my own experience, tappets do pump up and prevent valves seating fully which could also cause your problem. Do you think there is any chance the barrel base shims might be fitted to do more than just reduce the chances of detonation with poor fuel? Or am I just a bit cynical? Longer barrels or shorter push rods would stop valves meeting pistons, but I don't think the 0.5mm change is going to do a whole lot to the compression ratio. There have also been a good few exhaust valve failures with heads dropping off - perhaps bending the head of the valve slightly every rev. has something to do with it. The real cure would be to sort out the tappets and their oil supply as they have in Jabiru RSA. PS - think I would fit new valves.............

I have seen original style through bolts where a genuine aircraft quality AN 3/8 nut was a rattling fit due to the bolt threads being 10 thou undersize. If this type of assembly was torqued up, the threads change from being symmetrical to a "Christmas tree" profile which not surprisingly fails to hold the load. I recently carried out JSB013 on my engine and the new Jabiru supplied slightly longer through bolt threads were checked and all found to be within tolerance (Class 2). The ARP sourced nuts that are now used are available in a self locking style, just like the original MS nuts, so why are non-locking ones specified? If the MS nuts were good for a couple of thousand engines, why is Loctite 620 now used to glue everything in sight? To avoid distorted barrels when hot, careful torquing in stages is required. With Loctite 620 you have a couple of minutes before the whole lot goes solid and the torque measured is meaningless. On my engine it was necessary to chamfer the nuts to avoid them sitting on the barrel flange radius. The holes in the flange had a good 1.5mm clearance over the bolts which seems excessive and means the chamfered nuts are only bearing on a thin annular area. It also meant the barrels could be rotated slightly and had to be aligned to the block with a square. Are all the flanges like this, or is it just a dud batch like the oversize valve guides?

No it isn't, this one is shorter (and much older!)

Perhaps it's just an ugly rumour started by Rotax fans? Mutterings about it over here, thought those closer to the factory might have some facts.

Anyone heard of a new mod to the oil pump to reduce pressure pulsing? I am aware of the one from a few years ago which re-shaped the inlet and outlet ports. Nick