Experimental setup with turboshaft
Experimental setup with turboshaft
(OP)
Hello,
I am designing an assembly to test a twin-prop propulsion system using a Lycoming T53 turboshaft engine. There will be a a custom T-gearbox mounted to the front of the engine that will take the engine power and distribute it to two shafts coming out at 90degrees on either side, which in turn will power the two separate props.
I am not sure whether i can directly couple the engine output shaft with the gearbox, or a coupling of some kind would be necessary to make up for misalignment. The problem being the space constraint and that we'd have to go with an overly large industrial size coupling to handle the torque.
The gearbox mount will be CNC precision machined, though I don't have the exact dimensions of the mounting face on the T53, and may have to machine in multiple steps to obtain an accurate fit.
An image of the CAD geometry with the large coupling is included. Any input highly appreciated. Thank you.
I am designing an assembly to test a twin-prop propulsion system using a Lycoming T53 turboshaft engine. There will be a a custom T-gearbox mounted to the front of the engine that will take the engine power and distribute it to two shafts coming out at 90degrees on either side, which in turn will power the two separate props.
I am not sure whether i can directly couple the engine output shaft with the gearbox, or a coupling of some kind would be necessary to make up for misalignment. The problem being the space constraint and that we'd have to go with an overly large industrial size coupling to handle the torque.
The gearbox mount will be CNC precision machined, though I don't have the exact dimensions of the mounting face on the T53, and may have to machine in multiple steps to obtain an accurate fit.
An image of the CAD geometry with the large coupling is included. Any input highly appreciated. Thank you.





RE: Experimental setup with turboshaft
if you don't do this, then i think you'll need a coupling between the engine and the gearbox.
i suspect you'll need couplings where the prop shafts (from the gear box) attach to the props.
just out of curiousity, is the engine mounted along the line of flight (so the prop drive shafts have 90deg elbows) or across it (so you'd have a pusher and a tractor) ? will the props be rotating in the same sense, or opposite ?
RE: Experimental setup with turboshaft
The engine is mounted along the line of flight with 90deg elbow gearboxes at the props as you guessed, with the props counter-rotating.
RE: Experimental setup with turboshaft
Mike Halloran
Pembroke Pines, FL, USA
RE: Experimental setup with turboshaft
I'd definitely recommend getting a hold of a copy of an installation drawing/spec for your T53. I'm not familiar with the T53, but most aircraft turboshaft engines have very specific requirements for mounting.
The engine PTO is usually a female involute spline and your gearbox input would be similar. The shaft connecting the two would have a crowned male involute spline on each end, and these splines would have a major diameter fit. The input shaft's crowned splines allows some angular misalignment between the engine and gearbox. The splines would also need to have a recirculating lube oil flow to flush out debris. The T53 installation drawing/spec will give the dimensional details of the splines and the lube oil flow requirements.
As for the mounting of the engine, the requirements of the T53 installation drawing/spec should also be followed to the letter. Aircraft turboshaft engines have very lightweight structures and very tight clearances between the blades and cases. Thus they have very little tolerance for excess strains/loads. The engine is designed with a determinate mounting arrangement that provides the proper DoF at each mount, allowing for thermal growth as well as directing torque reactions and dynamic loads to the proper engine structures.
Lastly, you will also want to pay close attention to the dynamic characteristics of your drivetrain and any possible modal coupling with the T53. Once again, the T53 installation drawing/spec will give you guidance on this.
For tech info on your engine, give Honeywell a call with the specifics of your engine. I'm sure they'd be happy to help you out.
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I hope that helps.
Terry
RE: Experimental setup with turboshaft
RE: Experimental setup with turboshaft
RE: Experimental setup with turboshaft
That is an interesting design.
I have one question, what happens to those engines in the event of a crash?
They look like they would go straight through the passenger compartment.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Experimental setup with turboshaft
Typically rotating air mass impacting control surfaces and fuselage at various points has a significant effect on how it handles.
Seems like it could get a lot more complex with the engines repositioning.
I don't believe anyone will ever build these. It's like all the beautiful concept planes you see in AWS&T. No one ever builds them and survives.
In theory, there is no difference between theory and practice; experience suggests that in practice, there is.
RE: Experimental setup with turboshaft
RE: Experimental setup with turboshaft
Best Regards,
Jon
RE: Experimental setup with turboshaft
STF
RE: Experimental setup with turboshaft
Here's a link to the front section of the manual you will need for the T53.
The manual number is TM 55-2840-229-23-1.
Terry