When I has my Turbomin 100 it started and ran on kerosene. BMT claims that their BMT120 starts and runs on kerosene. Why would the other manufacturers not jump on this bandwagon? Is there some kind of a pattent issue at hand?
It seems to me the simlicity and reduced weight would make this worthwhile.

RC_Man,

Yep, it sure is simple and convenient to install and operate.

I suspect the main reason BMT is the only one to have it in production is the complexity of achieving consistent, reliable and low-egt light-ups on kero.

From an engineering and software pespective, Andre has invested an enormous amount of effort into making the 120-KS the engine that it is.

I'm sure Andre will chime in and add more detail.

Regards,
Garrett

Hi RC Man,
The reason for the success of the Kerosene start has a few components to it.
Firstly we developed an unique method of controlling fuel flow and pressure to a very accurate and repeatable standard. The intellectual rights to this method is my property and consist mostly of very specific software concepts. Only one other mnf of ECU.s has been given permission to use this technology and only for homebuilder use.
Secondly you need a well engineered combustor to startup efficiently with minimal heat stress on the engine.
You also need a very precision atomising fuel injector to be able to ignite kerosene consistently with only a glowplug as ignition source.
Then you also need to be able to deliver high pressure fuel to the injector while at the same time meter fuel to the low pressure vaporizer burners.
This is quite a tall order but with characteristic BMT innovation we have it working absolutely reliably. Every single owner of a BMT120KS has had 100% success.
I cannot obviously comment on why other manufacturers have not attempted this but it would appear that with the exception of one, maybe two, Autostart per se has been enough of a challenge already.
Even with the kerosene start as a feature, the BMT120KS is able to autostart with only 4 cell packs. The 120KS is also a unique design and we use a custom made high efficiency compressor to deliver 125 - 135N of thrust at RPM's of only 120K.
Availabilty of BMT engines have always been one of rather long waiting lists. Recently we took the decision to fully equip our workshop with the latest in CNC technology in order to be able to produce the quality parts we require in house. Attached is a picture of our new high precision 4 axis mill. We selected the American made HAAS due to its high quality and unsurpassed accuracy.
Cheers
Andre
[email protected]

Hi Guys,

I downloaded a start sequence from my plane and have attached the graph that shows the rpm and egt during the sequence.

I have placed the vertical scroll on the highest egt, which topped out at 640 degrees C.

Garrett

Hi All,
Since my last post BMT has made good progress in setting up our own CNC workshop in order to bring the quality we demand in line with realistic delivery times. First to come from our HAAS mill is the MK2 diffusor for the BMT120KS. Our thanks to HAAS CNC for the excellent support and general quality of their product for making this possible.
Thanks
Andre Baird
[email protected]

Rear view of diffusor. Note mounting wedge reinforcment for secure housing fixing at high pressure ratio achived with our new diffusor and custom compressor.

Man thats beautifull machine work. To me thats ARTWORK!

AJC

Wow! Seems like a shame to hide something that nice inside a plain metal casing !

Congrats on the progress Andre, and good luck for all the hard work that I'm sure still lies ahead.

Gordon

Hi Gordon, AJC,
Thanks for the kind words. Yes it is a lot of work but sure satisfying and fun. When I got into turbines 6 years ago I did not anticipate becoming a CAM CNC jockey as well...
Attached a pic of the case hiding them cute parts, not to shabby either.... But credit goes to my pal Rob there, as it needs a pretty heavy (read costly) CNC spinning machine to form regular 316 Stainless into that shape from flat sheet.
Why 2 Festo's when it only needs Kero you may ask? Well the festo closest is the return to the fuel tank system which allows the system to prime automatically with no operator intervention during startup. The gizmo in front of the plug is the fuel atomiser insert. Sorry, no detailed closeups available...
Cheers
Andre

Hi Andre,

Sounds like another neat little idea - no more pulling lines off and looking for jars to prime into, etc. So, I assume it does something like checking the engine RPM in order to decide whether the incoming fuel should be returned to the tank or injected for combustion ?

I know you are really thorough, so you're bound to have thought this all the way through - but I have to ask : what steps are taken to ensure that this doesn't cause an inadvertant flameout by having the fuel sent back through the overflow tube instead of into the engine ? (e.g if the RPM sensor dies).

Later,
Gordon

Hi Gordon,
The system utilizes two 3-way solenoid valves to orchestrate the fuel bypass, injector feed and vaporizer flow control. When both valves are de-energized the fuel simply flows into the feed and out the return. This means there is also no possibility of flooding the engine. All of this is under software control so when the startup sequence innitiates the pump runs at a 1/2 power to circulate fuel through the system. At the appropriate time the injector is energised to preheat the combustor. Once combustion temps are steady the vaporiser system valve meters a regulated amount of fuel to spool the engine to idle.
Should a flameout occur the valves are closed to prevent further fuel from entering the injector/vaporisers. The pump is also turned off. Should a pump malfunction occur the fuel will harmlessly flow back to the tanks.
All the hardware is under the front cowl and so is pretty simple to install from the users point of view.
Should the RPM sensor fail for any reason and the failure persists beyond what is considered safe, the engine is shut down/valves closed. This is unlikely as the magnetoresistive RPM sensor is extremely reliable and not subject to blockout like optical systems. This very system was pioneered by NASA for use on the Shuttle main engine turbopumps many years ago. If you look at the startup graph in Garrett's post above you will see just how smooth and quick this process is. The BMT logdata graph viewer software is almost out of Beta testing and should be available soon.
Another pic. This time of the almost "wireless" Turbine control unit. I really hate thick wires on PCB's so all the connectors are on the PCB, including that for the smoke pump. For those who may wonder, the code is just short of 64K of "C" and "ASM", can be loaded by the user from any PC. The TCU decrypts the file using a 1Kbit key when installing the new application.
Cheers
Andre