Kingtech K-120 acceleration delay settings question.
 

So, I'm still pretty new to turbines and have never really altered any of the settings. When I originally ran my 120 I noticed that she took significantly longer to go from idle to full throttle than the K100G on my trainer; in the realm of 7 seconds.

I flew the 120 in my F-15 a few times without incident, but on the fourth flight I tried to abort a landing for the first time, something I've done a few times on my trainer, but the slow acceleration seemed to prevent me from being able to make the abort and forced me to land off the end of the runway with fairly minimal damage considering.

I checked the log from the FC1 and there didn't seem to be anything amiss with the performance of the engine. She didn't flame out and was spooling up, but I was losing altitude and running out of runway so I had to cut the throttle and hit the fail safe before risking coming down in an area that could've caused damage to property or person.

The original acceleration delay setting was 008. I just fired her up in the back yard and played with the delay setting a little and managed to get it down to 005 with significant acceleration improvement (down to about 4 seconds), 004 didn't seem to add any further improvement.

So, my questions are, should I even be changing this value, or should I return it to the original? What are other people's settings for this engine?

FWIW, I'm running diesel and am at nearly sea level.

Thanks in advance.

I had the same issue on KT 120 last winter, and we opened up the pump limiting voltage and then did what you did and got the Acc Delay down to 3 before it began to huff on spooling up. I returned it to 4 and then locked the battery pump voltage back down to 700 I think. That was as far as it was willing to go and still accelerate smoothly. A very noticeable difference in spool times too by the way. I was running Jet A with KT oil and at sea level too.

Awesome advice, I check out the pump limit too.

What should I watch out for when adjusting the delay and pump limit? You mentioned "huff"ing?

"Huffing" is a slang term for a compressor stall. Just reduce the Accel Delay until you notice a slowing at some point in the acceleration during the spool up. Any unusual noise is likely a bit of compressor stalling where there isn't enough air to support the burn of that amount of fuel ( the burn moves rearward inside the engine making the noises). Then back off one or two numbers to alleviate the stalling. Most likely you will not notice the additional delay between say a 3 and a 4. The pump voltage needs to be taken up to its top before these tests to allow the voltage limiter NOT to reduce the effectiveness of the tests. Once you find the max number for the Accel Delay you can test once again with the pump voltage limiter back in place. There is a bit of interaction between these two settings for the obvious reason, so you may need to try it twice. Most likely from what you said already you will end up where I was at either 3 or 4 and the pump voltage cap set back to about 750 I think. It was a long time back and that engine is 5000 miles away so I can't check it. If you have more concerns simply ask Dirk or Barry for more info...
Enjoy,
Len

With the engine at full throttle, and max rpm reached (engine installed in plane), take note of the pump PW shown on the terminal. In the run menu, set the pump limit the the value noted at max RPM + 10-15% (ie; if max rpm was 500, set limit at 550-575). Accel Delay can now be set: advance throttle from idle to full quickly, each time lowering the delay value. When you notice a change in sound during acceleration (sounds a bit throaty, or you may see some flame), stop at that setting and add back two points. Cooler, dense air will allow for faster acceleration; warm thin air will require a slower setting.

Just an FYI - Pump PW reading on "Brushless" motors like a Merlin is actually pump RPM, as opposed to a voltage on brushed pumps.

i just picked up one of these k120g'S that just came back from twain and i to noticed the accel was a bit slow . dirk told me to lower the delay. i'm at 6 now . but he said nothing about the pump values. the engine has 86 min. now .it's starts really nice and has a reasonable time from start or run. i did have the expo set to half expo . i don't know if going to linear will help. any thoughts?

As Todd was talking about above.... air temp and humidity play a big part in it. SO... DO NOT tune your acc delay to the edge on a cool day. You may wind up with a flame out when it's hotter outside. Also... if you try to get your value too low (as it sounds throaty) you are actually pushing flames deeper into the NGV and turbine wheel. This will erode the parts faster... and can lead to cooking oil into the hot-side bearing.

I'm not saying to not change things as needed... but the slower spool-up on some of these engines is for safety. the more modern designs are simply more efficient and can spool quicker.

Just my 2 cents... take it for what it's worth.

thanks Doc. i am running it in the winter so i can imagine that would have a big effect on the spool up time according to what your telling me. it's starts very nice and does run good so i'll leave it till summer and run it then ,WB_1

also i'm looking for info on the telemetry for the xicoy ECU. i have a 28X and the fuel consumption feature is a huge leap forward i think . i think it will take a lot of the guess work out of trying to keep tract of your fuel . i ran out of fuel on a second flight of a new plane. fortunately i did make it back given the place where it happened ,but i don't want to relive that again lol

Hi WB-1. Just another note regarding your comment on the throttle curve. Depending on your aircraft, you may want to try linear. i did find on my jet with the K-120 that linear just seemed to feel better on throttle management, especially when changing to the landing config. I felt with the half expo I needed to come up on throttle too much when the jet was dirty versus clean config. Just seems more natural and now I just have to throttle-up a little to get the right landing config. Obviously this depend on the jet.

i agree. i'd rather know exactly what power setting i'm on while landing. i leave expo for control surfaces .

...

Your first step should be to call Dirk and go through your parameters. Sounds like it has been changed from stock.

626-808-6122

yeah that does sound a little slow. my G1 isn't the fastest spooler either but a bit faster than what your describing. please keep us posted

patrnfiyr is your throttle curve linear or half expo?

Just call Dirk
 

I think I am going to make shirts that say. " Just call Dirk " 10 min call can save you thousands in $ .

Easy boys, be nice.

https://cimg6.ibsrv.net/gimg/www.rcu...c42e5ada29.png
https://cimg7.ibsrv.net/gimg/www.rcu...a6a840b978.png
I've experienced something like that on my K80, this may be the reasons, step 10.

I got me my first Kingtech turbine and I'm still learning about them ( the brand ) one thing is for sure, support and the engine itself are excellent, I'm a happy owner.

I was

Not to say that there isn't a throttle delay, but do you think that the draggy scale Cougar vs a streamlined Bobcat doing an aerobatic maneuver may contribute to your needing more power sooner? Ie, the bobcat is able to use its momentum more efficiently for the maneuver needing the full throttle later vs the cougar?

I was the last of the "classically" trained turbine pilots in my area, and every turbine since the JetCat SE's seem like god sent miracles!

The last couple of G2 king techs I owned were "spin my head" fast.

https://cimg3.ibsrv.net/gimg/www.rcu...bc940f0d13.jpg
Then, you'll be able to fly this one :)