Jonboy2

My Feedback: (62)

I was wondering what others experience are as far as operating and flying smaller turbines at higher elevations? By smaller, I guess I am referring to the Xicoy X-45 or Kingtech K30/ K45. I fly in The Denver Colorado area which is roughly 5300 ASL. I bought a Xicoy X-45 several months ago and so far have just run it 4-5 times on the bench. So far, no issues. It starts up quickly and accelerates and de accelerates great without any problems. I have heard of others that have the Xicoy or KT that are having issues keeping these smaller turbines running at higher elevations. Just wondering what experiences others are having with these smaller turbines who fly at higher elevations. Thanks in advance for any responses. Jon

erbroens

We had dificulties at our place (3000 feet ASL) in the past with the wren 44 and the jetcat P-20, and even with the middle sized turbines if the spool up time is set to be too quick.

The K-45 is the only small turbine that worked here since day one without issues or tweaks. A very impressive little engine.

Zeeb

My Feedback: (41)

Just wait until you have your first 90 degree day and you'll find out exactly what the meaning is of "Density Altitude" and why these small engines, and all others, have issues. They have the same power loss issues as any normally aspirated IC engine. 'Bout 25% at your altitude and no where near 90 degrees. It goes above that 25% very rapidly when the temps start climbing above 59 Degrees F which is a standard day temperature for aircraft/engine performance figures......

sidgates

My Feedback: (2)

Jon,
I have a RAM500 that I fly in Denver. I had to slow the acceleration down to about 6-7 seconds to keep it from flaming out with fast full throttle. My WREN Super Sport had to be increased to about 5 seconds. The Super Sport had a weird noise when I went from full throttle to idle power rapidly. I video taped that noise and after WREN viewing they had me slow the deceleration till noise disappeared.
I have made 2 test runs with a Merlin100 in my scratch built F-94C and it handled the altitude with out of the box settings. The second run was high speed taxi test at Arvada field.
I have helped others who were flaming out on acceleration, but don't remember the engines they were using.
I thought the power loss at our altitude (5700ft) was more like 15% but not sure.
Jon, I think I bought a F-86D from you several years ago but not sure on that either. It is still sitting in my basement.

David Gladwin

Remember, you need to increase idle rpm as altitude increases to keep combustion at efficient levels. The compressor needs to turn faster in the thin air to deliver the minimum pressure required for combustion.

Full size jet engines do this automatically through the barometeric function of the engine control system , hydro mechanical. the BFCU, or electronic. Result is idle rpm will be very significantly higher to keep the compressor delivering the required airflow due lower density to keep combustion working sufficiently well to keep the engine running!

As a rough guess I would suggest raising the idle rpm by 2% per 1000 feet of altitude.

Desertlakesflying

My Feedback: (28)

All my Kingtechs run great at 5000' from the factory. My smallest is a 140, but a couple of guys have smaller and they don't have issues either.

Diesel and Kingtech oil. On rare occasion I will get a failed start when the temp is below 30 degrees, but it starts right up the second try, and after that the rest of the day.

David Gladwin

Well, if all well nothing to do, but if an engine idles at 5000ft it MAY well be possible to reduce idle rpm as altitude is reduced.

I am not familiar with Kingtech, but I do know that the latest JetCat ECUS DO have built in temperature and pressure corrects to adjust fuel flow in the same way as modern fullsize engines do.

That said, if engines with a simpler ECU s are not idling or accelerating well with increased altitude, then an increase in the idle value may be a starting point to better operation.

Zeeb

My Feedback: (41)

My first KingTech turbine was the 160 when it first came out. Near SLC Utah on a dry lake bed which has been used for model flying since time began, our efforts to get that engine going on an 85F day went nowhere.

We did everything we could think of and that little sucker just wasn't going to run so we got Barry on the phone which I was really impressed by as this was a Sunday, and he made some suggestions for ECU settings but it still didn't run right IMHO. Well my little buddy AJ was willing to give it a try and I'm glad it was him as I do not think I'd have gotten it back on the ground.

Engine went back to Barry, weeks later the factory was finally willing to release some information on the G1 versions; no one anticipated the engine being used at field elevations above 5000 ASL. The salt flats were 4300 ASL, add an 85F temp and the DA goes WELL beyond 5000 ASL.

At first they tried messing with the ECU, but no dice. This was going on four months that the Factory had my new engine and no estimate on a fix. Finally they announced that their new compressor turbine wheel design would not work at higher altitudes, so a new one was being designed.

On to six months and still no engine. I finally got Barry and told him I wanted either my fixed engine or a refund. A new engine showed up on my door step two days later via air freight from Taiwan and since it had a different serial number I'm certain it was a new engine as well as it being a G2 version.

This DA issue is just a fact of life and the reason that JetCat has the corner on the drone market for the Military, their ECU's will function just as David mentioned and can adapt for higher operational altitudes. A jet engine that cannot fly above 5000ASL isn't really any good except to possibly hobbyists.....

jetflyr

[QUOTE=Desertlakesflying;12660300]All my Kingtechs run great at 5000' from the factory. My smallest is a 140, but a couple of guys have smaller and they don't have issues either. <SNIP>
= = = = =

I fly with a club field elevation of 6950 feet in Colorado. It is dry up here which really helps boost the DA. Having flown a PST 600, JetCentral Super Eagle, Wren MW54 (home built, kit and standard), Wren 160's, MW-44's and now KingTech 45, 80, 85 and 140 in addition to a Merlin 100 - all have operated just fine up until 90* when the DA gets to be about 11,000 feet. The newer KingTechs and Merlin STILL have not missed a beat up to 95* ..... and then I melt. :-)
Several club members have gone with the Swiwin (sp) engines and they seem to perform just as well.
Today's combination of engine and electronics design seem to be fairly bullet proof, so having a dealer (stateside) who can take care of your needs - especially on the weekends when we actually have a chance to fly is a tremendously valuable variable.
Greg

David Gladwin

No sure what you mean by dry air boosting the DA.

Dry air is more dense than moist, thus lowering the DA.

jetflyr

I reversed things and misspoke

F900

My Feedback: (2)

I find ACEx or Swiwin turbines to be the best for high alt r/c fields, personally I think a lot has to do with how big the intake/ compressor area diameter is (bigger the better). Jonboy I knows we have flown 80, 120, 140, 170, 190 and 220 sized ACEx turbines and not one flame out, no hot start or any issues. I just think the front intake compressor area's especially in micro turbines is just too small for high alt flying. Maybe I am wrong but from my experience turbines with smaller front compressors over time end of having issues, especially during the hot summer and high altitudes and sometimes just not enough direct airflow into the intake and compressor. ... I'd love the mirco turbines but until one is proven to work at these alts, I won't buy one.

FrankFuss

Hi Jon,

I am in the Denver area and have a Whiplash Turbine helicopter, with a TS45i Heli Turbine Engine. Unfortunately, Turbine Solutions was no help when I asked if there was anything to be aware of at our elevation. Getting my engine to run was a major project. It did not work well with the supplied ECU parameters, and I had to experiment with ECU parameters to get it to start and run reliably. If your Xicoy engine is starting and running well, then you are in a much better position. Also, I found Xicoy a pleasure to deal with for a number of accessories that I purchased from them, so I would assume that they will give you great support.

One issue with my engine is that I found it very dependent on Air Density for it to startup and run well. I had problems on hot days (>90°) at the flying field. For it to work well, the Air Density must be greater than 0.950 kg/m3. I use the Density Altitude+ App on my iPhone to keep track of Air Density.

Frank

Jonboy2

My Feedback: (62)

Thanks guys for the discussion and info. I appreciate it.