[Chubs]

I would like to integrate an electric starter in my turbine. I have seen that people use bendix-style clutches to engage the turbine nut and get the turbine spinning. Can anyone tell me how this works? I have a video of the clutch working: http://jetbeetle.com/X150_image/bendix_clutch02.AVI. I cant seem to find anyplace to buy this thing, is there any way you can make it? Any information on this would be greatly appreciated.

Thanks

[Smurf208]

I am building a jet engine, and i've decided for starting the engine i'm going to use a small compressed air tank and spin the blades up to speed. You could use a regulator so it peaks at a certain ignition speed. I'm trying to build mine all the best ways in every way and i think using no extra motors or gears or mechanical devices is best. I think compressed air is a way better advantage then a extra motor, clutch, gears or waht ever mechanical you have to build and/or design. that way the intake is clear to suck unrestricted air in and this also cuts the weight down? If thats even a factor u need to consider. Well i thought i'd just run the compressed air idea by you, maybe it will save u time and money and practicality. All you need for the compressed air system is a little tiny tank with a hose with a nozzle. It could be fixed infront of the intake blades or have a removable type?? Easy to refill, just all in all a simple system that does the job

[Smurf208]

Did that help at all?? What have you decided on chubs?

[vulcom1]

Chubbs,
The electric starting you mentioned is in wide use on minature turbines. For start up and also the cooling down cycle. If I am not mistaken check the 5bears site as he may have made one. Lots of good info also.
Starting on air is okay if you carry a scuba tank like they used to but the problem with is not the starting. It is when you shut it down from the high temperatures. I think it is called thermal shock and all sorts of weird things happen to the turbine blades. This is why the new ones have control systems and they cycle till cool.
John

[Smurf208]

Wouldn't thermal shock only occur from the electric engine speed cooling the engine after it ran hot hot??? The air vs electrical motor starting wouldn't ahve any role in the thermal shock cause air would start it and then when u killed it, it would spin to a stop, in the process providiong a nice breeze to cool the parts... the thermal shock would occur if you were to speed cool the hot hot parts..... If your worried about thermal shock shuting down would be gradually lowering the temp of the engine and thats a matter of the ECU if the engines electronically controlled, i don't see any disadvantages from the air start up system, i think the electrical motor is a major disadvantage, cause you have to have electronics controlling the electronic motor, battery's, wiring, and then the clutch, air is just a valve and air hose with a nozzel if u want a nozzel.

[Chubs]

The only reason I want to use the electric start method is for the machining. It seems like a nice thing to machine and makes the engine look nicer in my opinion.

However, I have still not found any information on the bendix clutch. I checked the 5bears site, however, there is no real usable information on the clutch there, only that you can machine one yourself. I would be glad to email the owner of that site, but I cant seem to find his email on the site. Does anyone know his email?

Also, to what rpm should the motor get the shaft spinning before release.

Thanks

[pastera]

Try contacting someone from the Gas Turbine Builder Association.
http://www.gtba.co.uk/

That is where the author at 5Bears states he got the plans (members area)

Aaron

[LN-JET]

Hi Chubs,
If you are after the good looks of the starter, you can always do what I did, machine the starter mount yourself, and buy the clutch from Wren turbines.
It is not expensive, and you can always use it as a pattern, and resell it;-)
The wren bendix does not have a return spring, and it uses the magnetism in the motor casing to hold it in the retracted position.
The typical speed 400 usually follows to 17000rpm.
I recommend Graupner or Multiplex type 400 6volt motors.
Wren uses the Multiplex 280Ball bearing motor,it is very compact and can follov the turbine to 30000rpm without problems. GP electrifly 280BB is the same: http://www2.towerhobbies.com/cgi-bin...&I=LXAHK6&P=ML
You should have some possibility to short out the starter motor when you disconnect it, to get electrical braking. This will help retract the bendix.
All modern ecu's have this function.
Alternatively control the starter motor with an electronic speed control with brake function.

Lars

[merl]

Hey guys, I relize I'm very late in this discusion but, I should tell you I worked at SWB Turbines up untill just reciently and designing and building a "Bendex" style electric starter for one of the smaller model engines was one of my projects. It's really a very simple devise but, the one I made did have a spring return to ensure that the starting cup did not slip out and contact the compressor wheel nut under heavy accselleration.

[vulcom1]

There are several distributers that have the bendix clutch advertized. The Jetjoe has one for $8.00, starter mount $4.00 and a 6volt speed 300 for $6.00along with a bunch of other stuff you can use.
I was referred to the site when looking for parts and fittings for my KJ66 and after building this one will probably go with one of there's to try. I know they had lots of problems but a guy up here has 2 of the 1800's and says they run great. The JJ-1200 is an exact copy of the Wren 54 from what I here. Before anybody jumps on me about copying then they should look at all the others that started basically with the 66 design.
A basic JJ-1200 kit goes for $599 and I paid more than that for the three main parts and made the rest.
This is my KJ and what is left is the fuel system, setting the clearances and balancing. It has been fun and to finish the other I need the 66mm turbine and NGV. They are hard to get from Wren as they keep running short.
John