Well, the velocity does climb fast with a high fuel flow (I did however never put it higher as MP=36) and forgot the fuel flow. The plenum on the velocity did kept it under 400 (and being under 400 is good on a velocity, just bad for the engine, so you must count on a shorter life for the cylinders).
Cruising I was usually under 400 (but not by much), and I mixed ROP/LOP flights (just what I felt like doing, sometimes wanted to feel that I was going fast, and sometimes just saving money going the LOP route)
The most of my heating problems were with the turbo's, LOP was hard on them, the temps were then just under 1700 (1750 is max) and I never felt comfortable with this, but when I was going ROP the temps on the turbo's were lower (1650-1680)
-- Ronald
The IVP will climb much faster but you have to have excellent cooling and very high fuel flow to do it. George Braly did a seminar on engine cooling back a few years which I think is captured here in the archives somewhere. My main take-aways on cooling: you must have the exhaust tunnel extensions and you must insure that cooling air is guided around the bottom side of EVERY cylinder. The fuel flow specification is in the TCM document but it ends up being 43+ gph at 38"/2700rpm.
Put all that together and you can climb 2000 fpm at 140 knots and still be below 380 dF on the cylinders. Not many people feel comfortable doing that though....
What power settings does a velocity need to do that?
Colyn On Jun 13, 2011, at 7:50 AM, RONALD STEVENS wrote: Wow, this was just a great answer, not based on emotions but just pure calculations. Like to add that I have seen that a lot of 4p owners do not go higher then 18000ft (VFR 17500), and that this might be also because the climb does take a long time.
I have sit in a few Lancair 4p's now and one thing I noticed is that the climb rate is not really that great. (1000-1400 fpm), while my old velocity easy did 1800-2000fpm (but at 145 IAS).
Now I understand you guys go faster (+/- IAS 160) but climbing then to Level 250 take about 23 min. (more or less, they never let you go direct, right?)
Anybody has better numbers or better climb performance tips?
Another comment on winglets.
My theory is the most important speed is your SL speed. Suppose you are flying 1350 nautical miles. Westbound you have a 40 knot headwind at 5000 increasing to 100 knots at fl200. Eastbound let's say you get a 40 knot tailwind at fl200. (Doesn't it usually work out that way?)
Someone offers you mod A that gives you 10 knots at 5000 or mod B that gives you 10 knots at fl200. ...and let's say your plane does 225 knots at 5000 unmodified.
mod A gives you 10/(225-40) or 5.4% improvement which you enjoy for 6.9 hours mod B gives you 10/(270+40) or 3.2% improvement which you enjoy for 4.2 hours
So even if the winglets delivered performance up high they don't seem like a very good deal.
Colyn
On Jun 7, 2011, at 2:18 PM, RONALD STEVENS wrote:
Hello guys.
I like to introduce myself, I am 50, European/American, former Cirrus
SR22 (1100 hours) and
Velocity TXL5 (250 hours, just sold this plane)
(total 1400
hours).
I am a future Lancair 4p
owner (looking to buy one these weeks, so if
you know someone who
wants to sell his let me know) and looked at a few
Lancair 4p
already.
Now about the winglets
(my first question);
Some planes I looked at
had their winglets, some not. All those that did not had one told me it
doesn't do anything, the ones they had did told me it works great,
more stability etc, even
the CAFE report is telling that it produces
more stability at higher
altitude.
But…even the big Charlie
Kohler told me it doesn't add anything but more
drag...thus less
speed.
I have no experience
whatsoever with the Winglets. So my question to you
guys is, do you have any
experience telling you that it does work? (this
is more for pilots who
had both so they can tell the difference)
Thanks -- Ronald
Stevens
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