SPT5 Help (pics added)
 

Although I have a lot of experience with turbines and some experience with other T-props, but I have zero with the SPT5 V3.

My first question, probably the first of many, has to do the with spinner back plate and the SPT5 hub pictured. The hub on the older SPTs was flat I think, but this one has that large protrusion sticking out. There supposed to be a spacer that put in place before the back plate, or am I supposed to open up the back plate hole to slide over it and make contact with flange. I'm in the process of setting the engine formers and the answer to this question will dictate the final position of the engine.


http://www.rcuniverse.com/forum/atta...mentid=1988469

George

Me again :-)
Think technically that's the SPT-H hub, but answer is you open up the spinner backplate and counter bore the prop. You don't want to increase the leverage on the prop shaft short bearing spacing

Dave

George,

Get a 12MM prop reamer (or drill bit) and open up the spinner backplate then slap that baby on!

Your job will then be done. You will need to open up the back of the prop to 12MM too so it fits.

Lastly, I believe are about to discover why the masses all say..."if you want to be able to use the words reliability and power in the same sentence with turboprop in our R/C community...you need to be flying a Jetcat". Congrats on your new motor!

Boli

Thanks Dave and Boli!

That's what I thought, but wanted to be 100% sure before I set the formers.

Regards,
George

Dave / Boli,

What do you guys have your prop RPM set to in the ECU. Mine came set to 8300+ which I though was a little high. I have Biela 25x12x 3 and Mejzlik 27x10, should I reduce the RPM? I also have larger 3-blade Bielas 27x10x3 and 28x12x3 if they are better suited.

Also, I know JC just approved diesel use, and that my other two planes (non-JC) are running on. Have you or do you know of anyone running diesel on SPT5? I have kero-start, so don't know how it will handle the start on diesel.

any input is appreciated.

George:

I have two (2) SPT5 turbines. They originally came setup from the factory at 165.000 rpm but my dealer told me to bump them up to 170.000. That 5.000 rpm difference really made a change in performance in my planes.

Both are equipped with Biela 24 x 12 x 3 since the airplanes didn't performed well with the 25 x 12 x 3. I do think that Boli also runs a 24 x 12 x 3.

I have limited the propeller rpm to 7.400 rpm but in flight you rarely see rpm's going higher than 7.100 or 7.200 rpm.

I leave the prop RPM set high as it will not normally get there, and it keeps the turbine on full rpm. If you set it too low and unload the engine in a dive, the max prop RPM will be reached and the turbine can be throttling back.
I think the Biela 25 x 12 TP is a good match, 2 blade larger props will have a high tip speed and put a lot of load on the gearbox. The Raven is so light you won't be short of power. Our's had a 2003 SPT-5 on a 25 x 13 3bl Biela and its vertical forever. We are cool and fat with air, I can see the 24 x 12-3 working in heat.

Dave

Thanks guys! I trying for the maiden tomorrow if all goes well.

Any thoughts on the diesel and kero-start with diesel?

I'm sure JetCat told me the only turbine it did not work well in was the P-20, so I don't see an issue

Dave

Guys,

Thanks for all your help. And Dave, thanks for the specific guidance on the Air Trade Raven in the back channel.

The engine started and ran just fine on diesel, no problems there. The maiden was completed yesterday. It was very windy (turbulent) but all went well. There are a few tweaks to be made (White Rose brakes adjusted, aileron throw, cables tightened, etc.) and then just get more flight time. The 3-blade was alright, and although it was a different engine, it felt the same as my AW Raven's performance when it had the same 3-blade, so I think I will give the 2-blade a shot just see if it performs better as it did on the AW.

Thanks again all!
George

George,

Why do you run 2 UAT's ?
What is the dry weight ?
What sort of spoolup time are you getting ?
I bet that turbine sounds killer .....

I have a UAT on the smoke sytem, so that's the second one.
I haven't weighed it yet.
The spool up is probably around 2-3 sec. It is not an issue.
It sounds GREAT!!!

George

Glad it all went well, what didn't you like about the ailerons?
We have tracked down the original airbrush guy for these Raven's, so you never know there might yet be a brother/sister! I'm having one done for a friend with a JetCat SPT-10...should rock

Are you using the original light wing tube?

Dave

Dave,

The aileron roll was just too tame for me, but to be honest, I never "measured" the actual throw, just left it at 100% ATV (AFR for Futaba). With that said too, I'm sure there's 20-22mm, but I'll be measuring everything before the next outing. Light weight tube? IDK, the one I have is aluminum and feels pretty light.

SPT10? It may never want to land!:cool:

George. What arm length do you have? I have 1.5" arms. Its set up smooth, so probably about as ours.
Yep, I added a 1/4" ply X brace that extends 3" into each panel. Its just to stop the tube crushing.
Did I say to add raised ailerons? I have 1/2" raise ailerons for landing on our sub 300' grass strip

Bigger fan on the front will hopefully add more drag

Dave,

Yes, 1.5" arms on the aileron servos. Regarding the tube, I'll have to do that as well before I fly it "hard". And yes, you did mention the raised ailerons. I actually already have it programmed in, just didn't try it yet. I have no runway restrictions at my home field, but need to get used to it with the raised ailerons, so I'll be playing with it later.

R/
George