More Turbo and Leadville, CO

[jlunseth]

I went to the MAPA PPP in CO this weekend.  Saw a couple of people from this Board.  I took the mountain flying course, and what a beautiful trip it was.  My instructor and I flew to Buena Vista (KAEJ), which is 7,946 MSL and has an 8300 foot runway.  That was a piece of cake.  Then we went to Leadville, CO (KLXV) and landed on its shorter runway (6400) at 9,937.  We went to the terminal building and got their certificate for landing at the highest airport in the country, took some pictures and breathed the mountain air. 

I have to say that with the turbo, other than the landings and takeoffs requiring a little more runway, high altitude airports were just not difficult.  We were going to go to Gunnison and try another landing, but my instructor felt I had the landings pretty much in hand, so we went down south following the Arkansas River, past the Collegiate Mountains, Salida, south around Pike's Peak, and then picked up flight following from Co. Springs.  We overflew the Airforce Academy airstrip, then went back to our base airport, which was Rocky Mountain Municipal (BJC).

Class was over at that point, and my friend wanted to go to Boulder so we drove up there for the afternoon, had a great sushi lunch at Kasa.  I would highly recommend it to anyone with a taste for sushi.  Homemade soy sauce.

 

 

[Jeff_S]

How was the weather for the program? I was out in Denver last week and did a bit of mountain flying on Thursday, but we had to cut the trip short (only got to Steamboat, instead of Aspen and Leadville) because there were already storms in the mountains.

[M016576]

Sounds like a wonderful day...

[ToddDPT]

Great trip!

[jlunseth]

Weather was pretty good in the mornings.  Tstorms in the afternoon.  We had planned to go to Vail and Steamboat, but it was cloudy up there.  Fine with me, I wanted to go to Leadville more.  Steamboat and Vail are really pretty I hear, and I think we may go out there later in the summer.

The weather was an adventure on the trip home though.  Because of our trip up to Boulder and seeing the sights, we did not leave KBJC until around 5 pm.  Tstorms were encroaching on the airport and we departed in the rain.  The sweet spot for the trip back home was FL190.  There was an overcast layer over part of the route that topped at between 18000 and 18700, so we skimmed that most of the way home.  It was bumpy below that layer.

There were some cells along the route, we had to deviate to get around a couple with the help of the sat wx.  The adventurous part was that last couple of hundred miles.  There was a large supercell west of our course and moving eastward.  It stretched from about Yankton to well north of Minneapolis, and at one point was in the process of absorbing an independent cell it overtook along the way, sort of like a black hole absorbing a star, big S shaped stream running across our route from the independent cell to the supercell, not turbulent though. 

From the reports, and from the looks of things on the sat wx, we could make KFCM if we did not dawdle, and if worse came to worse we had clear air to the east, so we went for it.  I had the FBO put the plane away as soon as we got there, and about 45 minutes later the cell hit the western suburbs.

I am sort of in the early stages of looking for a different aircraft, would like more useful load, speed, and FIKI.  One of my instructors was telling me an Ovation would be good.  No knock at all on the normally aspirated aircraft, but I am not going back.  Am definitely sticking with a turbo. 

[thinwing]

Thanks for the Pirep...reminds me of a night I had to park the Mooney in springfield..a little ag strip 20 nm west of Yancton...really sweated out a supercell moving in and no way to hanger the Mooney...fortunately no hail storm that night..it pounded Yancton instead!!!I agree with you about the turbo...full gross takeoffs at 6/7 k field elevation are a non event...never landed at leadville though...kp couch

[jlunseth]

Full gross takeoff is a nonevent at Leadville also.  Still 100% power, just a little longer ground roll.

[donshapansky]

My Rocket has 100% power to FL240, otherwise known as critical altitude. Still climbs at 1000'/min at FL250. I have 800 hrs now in the left seat in 36 months, been everywhere in summer and winter, what a great combo of power plant and airframe. Finally got it fly LOP 15.5 gph and 70% power, all cylinders below 370F even in Texas on a summer day. The deal with LOP difficulty was excessive blowby even though the leak downs were all in the 70's/80, the TIT would blow through 1650 - 1700 during the leaning process. We found 2 stuck rings on 2 cylinders, after overhaul max TIT is 1625 F during the leaning process with 1550 F being the norm with all cylinders at least 50 F LOP.

Range is incredible, recently non stop Granbury, TX to St Cloud, MN (828NM) 4:35 hrs with 30 gals remaining. Return 2 days later from Fond du Lac, WI nonstop to Granbury, TX in 4:45 hrs with 18 gals remaining due to greater climb time and more climbing due to weather enroute.

But it looks like the mission is changing with greater payload needs and deice more needed going into IN in the winter and fall so I'm probably going to the 'dark side' as Don Maxwell puts with an Aerostar 700. So the Rocket will be for sale in a couple of weeks or less.

[aviatoreb]

Quote: donshapansky

My Rocket has 100% power to FL240, otherwise known as critical altitude. Still climbs at 1000'/min at FL250. I have 800 hrs now in the left seat in 36 months, been everywhere in summer and winter, what a great combo of power plant and airframe. Finally got it fly LOP 15.5 gph and 70% power, all cylinders below 370F even in Texas on a summer day. The deal with LOP difficulty was excessive blowby even though the leak downs were all in the 70's/80, the TIT would blow through 1650 - 1700 during the leaning process. We found 2 stuck rings on 2 cylinders, after overhaul max TIT is 1625 F during the leaning process with 1550 F being the norm with all cylinders at least 50 F LOP.

Range is incredible, recently non stop Granbury, TX to St Cloud, MN (828NM) 4:35 hrs with 30 gals remaining. Return 2 days later from Fond du Lac, WI nonstop to Granbury, TX in 4:45 hrs with 18 gals remaining due to greater climb time and more climbing due to weather enroute.

But it looks like the mission is changing with greater payload needs and deice more needed going into IN in the winter and fall so I'm probably going to the 'dark side' as Don Maxwell puts with an Aerostar 700. So the Rocket will be for sale in a couple of weeks or less.

[donshapansky]

The TAS is of course related to altitude, last week at 10,500 with 15.2 gph 32.5 " MP @2450 rpm the EDM 930 showed 70% power with 194 KTAS the TIT was 1565 F or 95 F below recommended max. GAMI says that the temp is not the concern but the exhaust side of the turbine can expand and strike the turbo housing, this is from the engineers at the turbo end of the business.

[jetdriven]

Does TAS depend on density altitude or just straight altitude?

[danb35]

On the E-6B, you use temperature and pressure altitude corrections to IAS to yield TAS, so I'd say it's density altitude.

[aviatoreb]

Quote: donshapansky

The TAS is of course related to altitude, last week at 10,500 with 15.2 gph 32.5 " MP @2450 rpm the EDM 930 showed 70% power with 194 KTAS the TIT was 1565 F or 95 F below recommended max. GAMI says that the temp is not the concern but the exhaust side of the turbine can expand and strike the turbo housing, this is from the engineers at the turbo end of the business.

[donshapansky]

The turbo has 2 turbine wheels, one is driven by exhaust the other is the compressor for engine intake air supply. The exhaust driven wheel is the the area of the housing that the TIT (turbine inlet temp) measurement is tanken, if this turbine wheel expands too much it can hit the inside of the turbo housing.

The first step you need to complete is to download the chart at the GAMI website and follow the instructions on a long flight where you can complete the form in .2 gph increments to see what the GAMI spread looks like on your Rocket. This data is faxed to GAMI and they will determine how many if any injectors need to be modified.

[aviatoreb]

Quote: donshapansky

The turbo has 2 turbine wheels, one is driven by exhaust the other is the compressor for engine intake air supply. The exhaust driven wheel is the the area of the housing that the TIT (turbine inlet temp) measurement is tanken, if this turbine wheel expands too much it can hit the inside of the turbo housing.

The first step you need to complete is to download the chart at the GAMI website and follow the instructions on a long flight where you can complete the form in .2 gph increments to see what the GAMI spread looks like on your Rocket. This data is faxed to GAMI and they will determine how many if any injectors need to be modified.

[donshapansky]

The turbine wheel expands as exhaust temp increases, probably a combination of centrifgal force which would relate to turbine rpm and exhaust gas temperature.

[carusoam]

"What would cause the turbine wheel to expand too much?" - aviatoreb

"expanding" on Don S.' response....

Consider the following regarding expansion of parts due to heating...

Think of it as related rates of expansion.  Turbo housing expanding slower than the turbine.  They both expand, but not at the same rate.

All materials will expand when heated.  They do this at different rates in/in/deg  or mm/mm/deg.

The turbine is made of a different material than the housing.  Thus rates of expansion will be different.

The turbine will also be hotter (overall) than the housing.  The housing has some cooling, the turbine is very surrounded in the exhaust gases.

The clearances are as tight as can be to begin with.  Not much room left for differential expansion.

Since it is practically impossible to measure the temperature of turbine itself, the next best thing is define a TIT not to exceed, and stay on the safe side of that.

Cylinders and pistons have a similar relationship with similar limitations.

Just some thoughts from atop my engineer's soap box...

Best regards,

-a-

[jetdriven]

Also, superheated turbine wheels glow white hot and actually "blade stretch" when overheated causing blades to rub the housing.

Quote: carusoam

"What would cause the turbine wheel to expand too much?" - aviatoreb

"expanding" on Don S.' response....

Consider the following regarding expansion of parts due to heating...

Think of it as related rates of expansion.  Turbo housing expanding slower than the turbine.  They both expand, but not at the same rate.

All materials will expand when heated.  They do this at different rates in/in/deg  or mm/mm/deg.

The turbine is made of a different material than the housing.  Thus rates of expansion will be different.

The turbine will also be hotter (overall) than the housing.  The housing has some cooling, the turbine is very surrounded in the exhaust gases.

The clearances are as tight as can be to begin with.  Not much room left for differential expansion.

Since it is practically impossible to measure the temperature of turbine itself, the next best thing is define a TIT not to exceed, and stay on the safe side of that.

Cylinders and pistons have a similar relationship with similar limitations.

Just some thoughts from atop my engineer's soap box...

Best regards,

-a-

[jetdriven]

Try cleaning them first before running thre GAMI test to establish an accurate baseline.  On our Lycoming IO-360 we cleaned the injectors and our spread dropped to such a small value we run LOP on stock injectors.  If course, the Continentals probably won't do that.  But you might only have to order one round of injectors to zero it out.

Quote: aviatoreb

That is very impressive Don.  I really need to get myself some Gami's - it is on my to-do list this summer behind just a few other mods first.

I don't understand your comment on "exhaust side of the turbine can expand and strike the turbo housing".