Jeffpro

My Feedback: (1)

Just wondered if there are other JetCat P100-RX owners who find that in hot sticky weather, their turbine won't run unless they set the idle throttle response setting to "very slow?"

These turbines come from the factory with idle throttle response set to "normal." Several people on RCU have switched to "fast" to decrease the throttle lag. But in East Tennessee this summer, where it has been routinely above 90 degrees with high humidity, my 100 won't accelerate at all unless I change to "very slow." On any other setting, the turbine tops off between 60,000 and 70,000 RPM and then starts coughing and sputtering. It then either goes back to idle or shuts down with a "Low RPM" indication.

This is my fifth JetCat turbine and none have ever been as sensitive to heat and humidity as the P100-RX. Anyone else seeing the same thing?

Dave Wilshere

Jeff

Talk with Bob, you have one of a small number of turbines released with an internal glitch on I think the combustion chamber.

Regards

Dave

Jetkopter

My Feedback: (1)

its not the combustion chamber, if its and early one the turbine wheel needs a slight tweaking. Give JetCat usa a call, Bob has a simple fix. And yes mine is sensitive to the high humididty and high temps.

Vincent

My Feedback: (61)

I have been running a P-100rx here in Phoenix where it is very hot and have had no issues. Our humidity does not get too high but the heat certainly does not bother it. I did have a Titan se at one time that i had to switch the setting to "very slow" in the summer.
Vin...

frema

no you all are wrong
itsnot the combustor ,or turbine wheel
its the front
jetcat doesnt do his home work
there is to much gap between the intake and the compressor wheel
i serviced so many engines from them , and all had the same mistake

Jetkopter

My Feedback: (1)

Well maybe they should hire you ! The guy asked for help, Im telling him that JetCat has a solution for his problem. JetCat does plenty of homework , makes plenty of motors and yes a few of them have problems when its hot and humid. When you build as many of them as they do, call me so I can check your home work!

Jeffpro

My Feedback: (1)

Let me add a little more to the story.

I sent the engine back to JetCat USA. They decreased the angle on the turbine blades. I reinstalled the turbine and tested it; same results.

I sent the engine back to JetCat USA a second time. Bob graciously sent me a new turbine. Even the new turbine won't accelerate unless I set the idle throttle response to "very slow."

I'm wondering if there is something seriously wrong with the design of the P100-RX. I have run my old P-60, my P120-SX, and my P160-SX hundreds of times in the same humid conditions, and they have never missed a beat! FWIW, I have a friend in Knoxville with a P100-RX and he is experiencing similar (though not identical) problems. His fails to start about 2/3 of the time (usually reporting low acceleration, although occasionally the error code is low temp indicating a possible flame-out). Bob has been very supportive throughout our travails with these engines, but if the problem is a design or manufacturing flaw, there's little Bob can do.

Is anyone in Florida flying P100-RXs? Surely they have to set the idle throttle response to "very slow" as well unless I've been unlucky enough to get two bad turbines in a row.

bevar

My Feedback: (27)

I flew mine all week at Jets over Kentucky last month and it performed flawlessly. I also fly it here in South Florida every week at the worst part of the day...after lunch when it's hottest and the humidity is quite high and it's spot on.

Beave

GSR

My Feedback: (145)

Mine runs great here on the coast. Much more hospitable environment though. Scotty

Jeffpro

My Feedback: (1)

bevar, looks like you and I are of alike minds! My P100-RX is on the same orange-and-white BobCat.

Funny...I brought my BobCat and P100-RX to Jets Over Kentucky. John Redmond spent 5 minutes trying to get the turbine to run and said "send it back. There's something wrong."

What's interesting is that we were both in the same place at the same time (same weather conditions, obviously), and my 100 wouldn't take fuel, while yours did. What is it about these 100s that makes two identical turbines perform so differently?

bevar

My Feedback: (27)

Jeff,

I've had 3 different motors on the "Bolicat" and by far...the P100 is the winner! I have not done a single thing to the ECU, change wise...I'm running it like it arrived out of the box with no adjustments anywhere.

It's weird you are having that issue...I dunno. I have almost 40 flights on the 100 now (a couple of hundred on the airframe) and it's golden!

Beave

Jeffpro

My Feedback: (1)

Thanks for the info, Beave. Now I know that there's at least one 100 out there that runs fine in the heat and humidity. Having to turn down the acceleration to the slowest it will go is inconsistent with every other JetCat I own. It's strange, though, that BOTH of the 100s I've owned have behaved almost exactly the same way. I'd still love to hear from other 100 owners so I can determine whether my experience is "normal" or an anomaly.

My friend, the other 100 owner, and I are going to work with Bob by phone tomorrow to see if ECU tweaks will solve the problems we're having. Maybe Bob can work a little turbine magic for us...

bevar

My Feedback: (27)

Jeff,

I'm wondering if its the ECU. Maybe an upgrade flash or something? Call Bob and ask him...

Beave

Jeffpro

My Feedback: (1)

Not an ECU problem, I don't think. I've tried two turbines, two ECUs, and two fuel pumps. Same results.

The manual does say that the "very slow" setting is for extreme temperatures and altitudes greater than 1000 meters. Some days our density altitude is exceeding 3,000 feet.

murdock0700

It appears thhis might be a resulf of an airborne JetCat virus Seems to me this same condition is getting to more engines than just the 100 and seems to have no geographical boundries. Coulld be the beginning of a Turbine engine Pandemic . What shall we do ?


http://www.rcuniverse.com/forum/m_11183148/tm.htm



H.M.

Jeffpro

My Feedback: (1)

I spoke to Bob Wilcox yesterday and he explained something to me that cleared up a common misconception. Setting the idle throttle response to "very slow" does NOT appreciably affect the spool-up time. Instead, it adjusts four other parameters accessible through the locked menus that essentially delay the point in the throttle curve at which acceleration increases. This is consistent with my finding that I get adequate throttle response from the turbine even when it's set to "very slow."

Bob went on to say that the engineers at JetCat probably should have used terminology other than very slow, slow, normal, and fast...something like very humid, humid, moderately humid, and dry. It has been VERY hot and humid in our region this year.

siclick33

That sounds like a smokescreen to me. If you raise the point in the throttle curve at which acceleration rate increases then the spool time will be slower. Whether that can be noticed in practical use is another question. If what Bob says is true then it begs the question why Jetcat bother with a normal or fast setting if it doesn't make any difference.

It sounds to me that Jetcat's terminology is spot on and Bob is just trying to make you feel better about having your turbine set to 'very slow'.

Vincent

My Feedback: (61)

There is also a "full throttle" setting on that page which stays at the "fast" setting. Like i said in a previous post i had a Titan se that needed to be set to very slow in the summer here in Phx and i really did not notice the difference. My P-100rx has 5+ hrs on it all flown in the summer and it has not missed a beat set at "normal".
Vin...

John Wanner

My Feedback: (17)

I have had the same problem here in Phoenix. My 100 ran great untill the humidty went up. Bob had me relearn my ECU and now it runs like it should.
I did move it to very slow and have not tried to move it back to very fast.

John Wanner

My Feedback: (17)

sorry relearn

rcjetsaok

My Feedback: (7)

Regardless of Engine brand, my question is, how to you " Tweak " a turbine wheel as Jetcopter claims, and how do you " Decrease the angle " of turbine blades as you report JetCat USA did. These items are Cast or CNC'd products... I don't think you can't just bend them to make adjustments.. Maybe I am in the dark in this. Can someone explain the process how this is done.

chrigui

same problem in one p-100 in our club

Jeffpro

My Feedback: (1)

I had no idea they could do this until JetCat told me they were going to "close down" the turbine blades. I said huh? They use a jig to do it, but that's about all I know about it.

Pepperpete

So what is the final verdict on this? I was literally about to pull the trigger on the P100 but the amount of reports of issues is much more than I anticipated. It can get muggy up here and I am downright concerned.

Jetkopter

My Feedback: (1)

Im only passing on as to what Bob told me. Turbine wheels are cast, not machined out of billet of material. Bob told me they have a fixture and a tool to re-pitch the wheel. Why dont you call him Im sure he would be happy to explain it. The nut shell version of what is being done is to use more of the thrust from the enging to drive the turbine faster at a given fuel setting to force more air into the combustion chamber to offset what is being lost to to the high humidity.Being that are engines are single shaft turbines when the turbine wheeel spins faster so does the compressor on the front of the motor. The result is more air with the same amount of fuel.