Hi,i'm climbing up to FL100 (with 98% RPM; Autopilot + ALT SEL + IAS). At FL100 the AP keeps the altitude and the plane starts accelerating...Then i reduce Torque:73% -> 218 kt / EGT: 530 (EGT-Limit: 580)Now i try to speed up a little:73.5 % -> 221 kt / EGT: 534 (EGT-Limit: 583)And then:73.8 % -> 222 kt / EGT: 536 (EGT-Limit: 583)Now the rate of acceleration is climbing faster and faster without me. Finally:73.2 % -> >250 kt / EGT:540 (EGT-Limit: 596)What's going on here?Thanks for help.

I am not quite sure what your question is. Torque and EGT limits change with altitude, temperature, pressure, speed and so on. You climbed at near full power and then leveled off to cruise at FL100. You are still at climb power so the aircraft will accelerate until power and drag are balanced. If something changes the power (or the drag), then balance changes and the difference between 73% and 73.8% is really not worth mentioning. At higher air-speed there is more air cooling, so permitted EGT is higher.

I think I know what Wlofgang means, I had it few times too. I have descended to FL080 and tried to set IAS about 220KTS, but to some pint (first mark on EGT) the aircraft was slowing down, and after this point it was accelerating to over 250KTS.

I think what you are seeing is the effect of reduced angle of attack as the plane speeds up. I've seen something similar to what you describe several times climbing to cruise and leveling off.

@Sawydz and trisager:That's my point. I testet it several times (with 98% RPM and 96% RPM) and the result was the same - at one point: accelerating over 250 kt.Now, what are you doing to avoid it? What do I have to do to e.g. cruise with 230 kt on FL100 ?Another question:If you cruise with e.g. 240 kt, what are you doing if ATC says: speed 220 kt ? Is there a "rule of thumb" ?Thanks again.

@Sawydz and trisager:That's my point. I testet it several times (with 98% RPM and 96% RPM) and the result was the same - at one point: accelerating over 250 kt.Now, what are you doing to avoid it? What do I have to do to e.g. cruise with 230 kt on FL100 ?Another question:If you cruise with e.g. 240 kt, what are you doing if ATC says: speed 220 kt ? Is there a "rule of thumb" ?

I'm still not sure I completely understand where you are coming from, but the answer is simple: reduce power. Pull back slowly on the throttles until you achieve the desired airspeed.Are you getting power settings from a chart, perhaps?

@Sawydz and trisager:That's my point. I testet it several times (with 98% RPM and 96% RPM) and the result was the same - at one point: accelerating over 250 kt.Now, what are you doing to avoid it? What do I have to do to e.g. cruise with 230 kt on FL100 ?Another question:If you cruise with e.g. 240 kt, what are you doing if ATC says: speed 220 kt ? Is there a "rule of thumb" ?Thanks again.

Unfortunately I fly only offline, so I'm simply reducing power. Sorry but I can't help more.

I'm still not sure I completely understand where you are coming from, but the answer is simple: reduce power. Pull back slowly on the throttles until you achieve the desired airspeed.Are you getting power settings from a chart, perhaps?

Then I'll try to explain: Let's say that I'm at 8000ft flying 212KTS and I want to accelerate to 220KTS, but its impossible because when I add a little power the aircraft starts to accelerate to over 250KTS, and the only way to slow it down again is to reduce power significantly.

Edited August 24, 201015 yr by Sawydz

I try to reduce power correctly to achieve e.g. 230kt, but either the plane reduces speed to much (so i get 210kt for example) or i get to much speed ( >250kt).As i tried to explain in my first post:at e.g. 73% torque i get 218kt and at 74% torque more than 250kt. there's no chance to get a speed between...No, i don't get power settings from a chart.The problem is on- and offline...

Then I'll try to explain: Let's say that I'm at 8000ft flying 212KTS and I want to accelerate to 220KTS, but its impossible because when I add a little power the aircraft starts to accelerate to over 250KTS, and the only way to slow it down again is to reduce power significantly.

I see what you mean (apologies for being a bit dense here :( )What happens if you cruise a bit higher, around 15,000 ft? Does that allow you to find a power setting that gets you the speed you want?I'll see if I can get it to cruise at 230 kts /10,000 ft on my system.

You can nail an IAS with power but it is not normally done this way. Usually, we fly at given power settings and the IAS is the result. I like about 65-68% torque unless I am temp limited, which trues out at near 300 kts TAS at 15000.

I see what you mean (apologies for being a bit dense here :( )What happens if you cruise a bit higher, around 15,000 ft? Does that allow you to find a power setting that gets you the speed you want?I'll see if I can get it to cruise at 230 kts /10,000 ft on my system.

Yes, when I fly higher everything works perfect.

You can nail an IAS with power but it is not normally done this way. Usually, we fly at given power settings and the IAS is the result. I like about 65-68% torque unless I am temp limited, which trues out at near 300 kts TAS at 15000.

That's true, but in this case, the problem is not technique but the fact that increasing power by the smallest step possible is causing the plane to accelerate more then 30KTS. I see this behavior for only last two days, it wasn't present before and I fly my J41 everyday since May. I'm sure it wasn't present because I was learning to fly this bird at short distances at FL080 and I had no problems. It's not a big issue since I don't fly online, but I will pay more attention from now on what's going on when I fly lower.

but in this case, the problem is not technique but the fact that increasing power by the smallest step possible is causing the plane to accelerate more then 30KTS.

I have experienced this also in the past week & a half I've had the plane. Seemed there was no throttle setting for between 215-220kts and 250+ KIAS.Well tonite I did a test with Clear Skies Wx Theme, stepping up the Torque in single F3 increments ( 1% or less change each step). Departed KFLL Airport with 100% Fuel and only Flight Crew of 353lbs... Climb to 10,000 MSL. Autopilot on HDG and ALT Hold.I noticed that when moving from 75.8%: 225KIAS(261KTAS) - FF 719lbs/hr - EGT 518°Cto next step of 76.4% with FF ~725lbs/hr and EGT ~525°CAirspeed would increase to >250KIAS until the Aircraft Overstressed. No idea what is going on here. :(

You can nail an IAS with power but it is not normally done this way. Usually, we fly at given power settings and the IAS is the result. I like about 65-68% torque unless I am temp limited, which trues out at near 300 kts TAS at 15000.

I agree with you about power settings Dan... you pick a certain Percent based on the performance charts... who cares exactly what a/s; you get what you get. Except in this case there seems to be no choice between "a bit too slow" and "way too fast."

Did you finally find out how to set up a stable 220 KIAS speed at that altitude? I'd also be interested in the secret because I also seem to be either very slow or go overspeed., could not stabilize airspeed @ 220 KIAS or something like that.