Archive for March, 2011

Not Quite Oomph!!!

Posted in EggDev with tags , , , , , on March 30, 2011 by eggmotor

30.03.11: Sam and I conducted another bathroom scales test at the weekend and amazingly and also annoyingly only achieved around 35kg thrust??? I’m not sure how accurate this method is but the carb jetting is much better/richer now than the last recent scales test when we got around 38-40kg thrust (see previous video). I can only speculate that is type of testing is quite flawed……… Well that’s what I’m hoping any way.

So to try and get some accurate information regarding the prop’s performance I’ve pestered Xoar again for some technical data for the 36x10PJD-P prop. When I asked them for the data a good year or so ago they didn’t have any. Thankfully they now have the relevant information and Rebecca from Xoar emailed me the PJD-P 36×10 data yesterday. (I also have the ‘old’ PJD-P 34×10 available too for those of you who may require it)

Unfortunately, when I checked the data, the 4900rpm I achieved in the garage a week or two ago doesn’t equate to the 45kg thrust I was expecting with my own calculations. It is more like a meagre 42kg thrust instead. I need to achieve 14.5hp/5000rpm in order to get the 45kg (44.7kg according to data) performance I’m wanting, the 4900rpm we got only equates to 13.5hp.

I’ve ordered a Pulstar pulse plug to try and achieve improved combustion and may be squeeze an extra fraction of thrust.

I will update soon…..

Extra Oomph???

Posted in EggDev with tags , , , , , on March 23, 2011 by eggmotor

23.03.11: Well we finally got to thrust test the Egg with the new head and carburettor combo a couple of weekends ago and things didn’t go to plan. As you can see from the video below, we only peaked 38kg thrust which is 2kg less than with the previous cylinder head and stock carb. I wasn’t sure where the problem might have lay and so doing some quick, rough calculations it appeared we were only getting about 4500rpm.

Any way, I took the spark plug out as I suspected it might be running lean with the stock jet fitted (size about 0.88mm) and after I uploaded an image of the plug to a couple of forums the general concensus was that it was quite lean indeed. I had a spare 1.00mm jet lying around and so I fitted it and did a quick rpm test in the garage and I achieved 4900rpm. Yippee!!! If those previous rpm/thrust calculations are correct then that shows that the Egg should now be pushing about 45kg(99lb) thrust.

I then checked the plug again and it still looks a little lean so I contacted Shane at AGK stating the engine specification and asking what would be the best jet size and he reckons about 1.05-1.1mm. So I’ve ordered and now received some suitably sized drill bits and I will be drilling the jet out to probably 1.1mm either tomorrow or the weekend. I might even squeeze a few more rpms and a smidge more thrust too.

So watch this space, the Eggmotor could soon be exceeding 45kg thrust. Lets hope reliability holds up 🙂 New thrust test will be taking place very shortly.