Hello everyone,

Since my last thread was sort of a question/answer session, I will devote this thread to the project build-up. Most of my questions have been answered and we have made great progress, so now it's time for pictures.

Testing the glow plug on my new power source.


It works!

Keyed entry is built into the circuit, it's wired right into the starter motor so you cannot start the engine unless you have access.

Fuel pump is ready for some juice.

Can I ask you what a Turbo-DAC is??? [sm=71_71.gif]

I was about to ask the very same thing

Ditto ... also, what is it that makes this an "Official" thread.

The DAC's I know of are "Digital to Analog Converter", and "Design Automation Conference" - neither of which seem to fit here

Cheers,
Gordon

I'm guessing along the lines of Data Acquisition Cell. Just a WAG...

Come on guys, try to keep up...
http://www.rcuniverse.com/forum/m_6454322/tm.htm

Thanks Mark P!


Yes, DAC stands for Data Acquisition Console.



Gordon,

The fact that I'M calling it official is what makes it official.



- Dan

I was way off. Here's mine. Except I just call it the lie detector. I need a flashier name! [8D]

And it has a analog gauge ,,, so much for the Dans' masters degree project

The analog gauges are at-a-glance engine monitoring, foolproof for the user. Incase the PC computer crashes while the engine is running, the user can still see vital engine parameters!! I'm a car guy, so I bought a boost gage

The data acquisition we will be using is LabView through a huge array of Omega transducers.

On the list we have a 0-100 lbs load cell part number LC-304-100 on the omega website. It is in the picture in my first post, used to measure thrust of course. Notice the linear bearing mounted on the underside of the engine.

The fuel flow rate is measured by an FLR-1012 flowmeter again from omega, pressure is omega PX-302 0-50 psi absolute pressure transducer.

Temps are the average K-type thermocouple, SS sheath 1/16" Dia ungrounded. We are finding new ways to snake the thermocouples and pressure transducers into the engine without affecting the engine performance and structure.

Data acquisition and transfer is done by the OMB-DAQ55 omega A/D converter. USB compatible, plug and play, easy! It also has 5 outputs!

All sensors require some power, power sources are accounted for sensor excititation bla bla bla etc...

Sensor outputs are mostly analog 0-5V for pressure and flowmeter or 0-10V for the Load cell (it is dependant on excitation voltage a ratio of 10mV/V output).



Today I spun up the engine on my new 7.5V power source, boy does this thing spin up fast without the current limitations of a 7.2V battery... Woooosh!


- Dan

Don't spin it up too much without lube in the bearings.

Ok,

I put some lube in the bearings a couple days ago just to keep them wet. Thanks for the heads up.


- Dan

UPDATE:

Hello everyone,

these passed few weeks have been very busy for the TURBO-DAC team. We got our last parts in the mail this week and assembled her for the maiden run. Everything was hooked up and A-OK.

Here's the breakdown.

As you all know, TURBO-DAC is an educational tool for our University. It is built around the Wren MW54 Mk3 model, to teach students the fundamentals of gas turbine theory and operation.

All engine parameters will be logged using Labview software and plotted for numerous different engine characteristic and response calculations.

Today we finally got the engine running, although we had never done this before, we were persistant to get her started.

Sitting with the start button, i cranked open the propane (it's a BBQ regulator that suits our purpose) and turned on the glow plug. EGT's were low for the most part, and we could not get the EGT's to 100C for about a good 5 minutes fiddling with the starter.

After some frustration seeing the EGT creep up to around 80ish, all of a sudden the EGT hits about 100 and then moments later we hear the ECU kick in the fuel pump. At this point i forget whether or not i should have took my finger off the starter or keep it on, or keep the propane on or shut it down. Glow plug, sort of left it on to keep things going. In any case, it idled on its own power, it was great!!

We were having some electrical issues with our power supplies but even for the 5 or 6 seconds that it did run, we really learned a lot about how to start it. It's not easy but we got the hang of it!!

Tomorrow we will attempt another start and we'll take videos. If anyone has any tips to give us, please tell me what we did wrong so that we can make our next start faster than this one.

Also, the engine ran for about 10 seconds tops, i am worried that when it shuts down that the bearings just sit there real hot. I took some compressed air and blew it straight into the impellar, am i paranoid? Will the engine burn itself up by just sitting there after a run or should i cool it down 'somehow'.

Thanks for all help!

- Dan

Just a few tips from a non-expert.

It should only take a few seconds to ramp up. Too much air or not enough propane will keep the temps down below ramp temp. Give it more propane or pulse/blip the starter to keep the speed lower to let the temp come up without flames out the back (it's a balancing act). Once it starts to ramp on kero, keep the starter fully engaged till about 28,000 which will come quickly. Turn off the glow plug and propane any time after it is ramping well. The exact time isn't critical. After shutdown cooling air in the intake is good or use the starter to cool it down to about 110 C.
Also make sure the thermocouple is the proper depth into the exhaust cone.

Why did it only run for ten seconds? It takes longer than that to spool up to idle. What was the RPM?

Sara from Wren will answer any questions you have. She is the expert.

Hello,

today we ran the engine again. It started up well and idled well, temperatures were high 700s but were reduced to sub 600s when she found idle.

It sounds great!

But there is a problem, the starter motor mounted to the FOD screen has a black plastic cap. This cap tends to rotate in place due to the huge forces imposed upon it from the air being sucked into the engine. The cap rips the starter motor wires while it turns.

We want to leave the cap off but that is not aesthetic, what should we do if we dont want the cap to rotate?


- Dan

????
Doesn't sound right. Are you sure the starter is disengaging?

I am pretty sure it is disengaging, i hear it pull back.

Also, i tighten down the 3 set screws pretty snug so the starter is not moving in place. It is definately the cap


I will run it without the cap and see what happens.

- Dan

I think we fried our starter motor. I dont know how but it wont spin when we click the switch, only when we manually pull the clutch out by hand will the starter spin on its own power. I dont know what the deal is with this starter, it may have gotten stuck to the engine and spun to 80k rpm?

I think we may need a new starter.

- Dan

Ok its not the starter, there was some glue on the back of the starter and it melted the glue and jammed up the starter. The glue was removed and the starter works fine.

Engine runs fine, today was a good day.




- Dan

Hello everyone,

New updates from Turbo-DAC at FIU.


The engine was ran again today, it runs really great! We got our DAQ system up, we use an omega 15 channel OMB-DAQ-55 board that is USB capable. It is going to record all pressures and temperatures of the engine. Labview was installed, software is ready!

There is a small problem though, we use the glow plug panel and it seems to be malfunctioning. It requires a 12V input, then spits out 1.5V for the glow plug. Well all of a sudden, while the jet was running the glow plug panel light shuts off. Turns out the panel spits out 11V instead of 1.5V, 11V is enough to fry a glow plug i suppose!

I dont know why it did this but the little hobbico glow plug driver panel (as seen in the pictures above) has been fried. We are using a steady 12V power supply.

In any case, it is no big deal.

- Dan

Make sure you turn off the glow plug power as soon as the engine is running or it will soon burn out. Try hooking up another plug to the panel. It should only pull enough voltage to power the plug, but if measured directly with no plug will read 11~12V.

Thanks Mark P!!!

We will hook up another plug and test it out.




- Dan