SR20 performance trivia

I’ve just returned to BLM, NJ after a bit of an odyssey - a trip from home to Pittsburgh PA, Chicago IL, Oshkosh WI, Omaha NE, Denver CO, Douglas WY, Billings MT, Portland OR, Crescent City CA, San Francisco CA, San Diego CA, St. George UT, La Junta CO, Kansas City MO, Columbus OH, Wheeling WV and finally back home.
In all, the trip spanned three weeks, about 59 hours on the meter, of which better than 50 was in the air.
Some of the flights were in extremely hot conditions, prompting me to remove the landing light (N84MR is an SR20) in an attempt to improve cooling. If it made a difference, it wasn’t an obvious one. Keeping the nose low, speed up, and boost pump on, seemed to help the most. Oil temp often went to 220 anyway, and it was rare to see it lower than 190 even in LOP cruise.

On one leg, from SGU (St. George) to LHX (La Junta), I was cleared from 15,000 feet (as filed) to 16,000 (to take a “short cut” I had requested). The climb up to 15,000’ had me wondering whether I could REACH 16,000’ - it had taken me 12 minutes to climb the last 600 feet (i.e. 50 fpm). I did get to 16,000, although by the end of the climb, I was doing MAYBE 20 fpm. This was a comfortable altitude at which to cross that portion of the Rockies (except for the O2 stuck up my nose), but I was starting to wonder about the claimed service ceiling – until I did a density altitude calculation. With 30.25" HG in the Colesman window, and the OAT at 42F (5.5C), the D.A. was better than 18,000.

  • Mike.

Of course, I meant the Kohlsman window…

  • Mike.

Mike: Can you share any information regarding your choice of oxygen equipment. I am aware that the POH mentions Mountain High and specifies the unit and the flowmeter, and that Aviation Consumer rated Mountain High a good system with the exception that they did not think that the carrying case was adequate. What I am interested in is what choice regarding the cubic foot size of cylinder and choice of material for the cylinder. Any specifics?

I’ve just returned to BLM, NJ after a bit of an odyssey - a trip from home to Pittsburgh PA, Chicago IL, Oshkosh WI, Omaha NE, Denver CO, Douglas WY, Billings MT, Portland OR, Crescent City CA, San Francisco CA, San Diego CA, St. George UT, La Junta CO, Kansas City MO, Columbus OH, Wheeling WV and finally back home.

In all, the trip spanned three weeks, about 59 hours on the meter, of which better than 50 was in the air.

Some of the flights were in extremely hot conditions, prompting me to remove the landing light (N84MR is an SR20) in an attempt to improve cooling. If it made a difference, it wasn’t an obvious one. Keeping the nose low, speed up, and boost pump on, seemed to help the most. Oil temp often went to 220 anyway, and it was rare to see it lower than 190 even in LOP cruise.

On one leg, from SGU (St. George) to LHX (La Junta), I was cleared from 15,000 feet (as filed) to 16,000 (to take a “short cut” I had requested). The climb up to 15,000’ had me wondering whether I could REACH 16,000’ - it had taken me 12 minutes to climb the last 600 feet (i.e. 50 fpm). I did get to 16,000, although by the end of the climb, I was doing MAYBE 20 fpm. This was a comfortable altitude at which to cross that portion of the Rockies (except for the O2 stuck up my nose), but I was starting to wonder about the claimed service ceiling – until I did a density altitude calculation. With 30.25" HG in the Colesman window, and the OAT at 42F (5.5C), the D.A. was better than 18,000.

  • Mike.

I’ve just returned to BLM, NJ after a bit of an odyssey - a trip from home to Pittsburgh PA, Chicago IL, Oshkosh WI, Omaha NE, Denver CO, Douglas WY, Billings MT, Portland OR, Crescent City CA, San Francisco CA, San Diego CA, St. George UT, La Junta CO, Kansas City MO, Columbus OH, Wheeling WV and finally back home.

In all, the trip spanned three weeks, about 59 hours on the meter, of which better than 50 was in the air.

Some of the flights were in extremely hot conditions, prompting me to remove the landing light (N84MR is an SR20) in an attempt to improve cooling. If it made a difference, it wasn’t an obvious one. Keeping the nose low, speed up, and boost pump on, seemed to help the most. Oil temp often went to 220 anyway, and it was rare to see it lower than 190 even in LOP cruise.

On one leg, from SGU (St. George) to LHX (La Junta), I was cleared from 15,000 feet (as filed) to 16,000 (to take a “short cut” I had requested). The climb up to 15,000’ had me wondering whether I could REACH 16,000’ - it had taken me 12 minutes to climb the last 600 feet (i.e. 50 fpm). I did get to 16,000, although by the end of the climb, I was doing MAYBE 20 fpm. This was a comfortable altitude at which to cross that portion of the Rockies (except for the O2 stuck up my nose), but I was starting to wonder about the claimed service ceiling – until I did a density altitude calculation. With 30.25" HG in the Colesman window, and the OAT at 42F (5.5C), the D.A. was better than 18,000.

  • Mike.

Mike, What was your usual TAS?

Mike,
I think you actually meant the Kollsman window. The sensitive altimeter was introduced by Paul Kollsman in 1928 (see http://www.kollsman.com/aviintro.htmlhttp://www.kollsman.com/aviintro.html). Kollsman, Inc. is still very active in the aircraft instrumentation business.
Cheers,
Roger

Of course, I meant the Kohlsman window…

  • Mike.

Mike,
I think you actually meant the Kollsman window. The sensitive altimeter was introduced by Paul Kollsman in 1928 (see http://www.kollsman.com/aviintro.htmlhttp://www.kollsman.com/aviintro.html). Kollsman, Inc. is still very active in the aircraft instrumentation business.

Cheers,

Roger

Roger,

Thanks! I appreciate the correct info.

Mike.

Mike: Can you share any information regarding your choice of oxygen equipment. I am aware that the POH mentions Mountain High and specifies the unit and the flowmeter, and that Aviation Consumer rated Mountain High a good system with the exception that they did not think that the carrying case was adequate. What I am interested in is what choice regarding the cubic foot size of cylinder and choice of material for the cylinder. Any specifics?

Stephen,

Mine is the Mountain High AL-647 cylinder (= Aluminum, 647 Litre, or 22.8 cu. feet.) I’ve been trying to find out how long this is SUPPOSED to last; I know from experience that it is more than adequate for two people at 16,000 feet for 3 hours. When full, the gauge shows about 2,000 PSI; now, after 6 man-hours of use at 16,000 feet, it shows 1,200 PSI.

I’m happy with the system, including the carrying case. Recently, an accident resulted in one of the nylon couplings breaking; their Tech Support was very good, and a new one was sent by overnight mail (not free, though).

  • Mike.

Mike, What was your usual TAS?

Well, it varied, of course, depending on the altitude and how I was setting the engine (power, leaning, etc.). At the high altitudes, I found that I couldn’t really run L.O.P. and keep the engine smooth; so I ran R.O.P, and was getting around 138 kts.

Lower down, I ran at an estimated 65% power (L.O.P.), and got closer to 142 knots. I wish I could give you a real average, but it seemed to be different for each flight. One thing I can say for sure is that I can’t seem to get much above 150 knots TAS even at 75% power at 8,000’; although I used to get around 157. I’ll have to look into that.

  • Mike.

Lower down, I ran at an estimated 65% power (L.O.P.), and got closer to 142 knots. I wish I could give you a real average, but it seemed to be different for each flight. One thing I can say for sure is that I can’t seem to get much above 150 knots TAS even at 75% power at 8,000’; although I used to get around 157. I’ll have to look into that.

  • Mike.

A layer of dead bugs on the leading edge, or dirt on the wings, can take at least five knots off of your TAS. The SR22 loses 5-10 knots when it gets rained on. Those are some pretty optimized airfoils!

Mike, What was your usual TAS?

Well, it varied, of course, depending on the altitude and how I was setting the engine (power, leaning, etc.). At the high altitudes, I found that I couldn’t really run L.O.P. and keep the engine smooth; so I ran R.O.P, and was getting around 138 kts.

Lower down, I ran at an estimated 65% power (L.O.P.), and got closer to 142 knots. I wish I could give you a real average, but it seemed to be different for each flight. One thing I can say for sure is that I can’t seem to get much above 150 knots TAS even at 75% power at 8,000’; although I used to get around 157. I’ll have to look into that.

  • Mike.

Mike, PUT THE FLAPS UP!..Ed

Mike, PUT THE FLAPS UP!..Ed

Ed,

I did - that was the easy part. Retracting the gear… now THAT was a trick!

:slight_smile:

Mike.