Checked True Airspeeds Today...happy camper!

timwinters

timwinters

Ejection Handle Pulled
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Conway, MO
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LTD
So, it's a beautiful day to fly here today. I had nowhere to go but wanted to fly. The new engine has over 75 hours on it...well broken in by now...and I knew I've been getting better airspeeds than before the OH but had never checked to see exactly how much better. So I thought I'd go check it out today.

At both of the below listed altitudes the engine was almost WOT (backed off just enough to close the "enrichment function"), leaned until rough, enrichened until smooth. Density altitude was pretty close to actual this morning.

1958, C182A
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@5500':

23/2300 (73%), 12.5 gph, OAT = 8dC.

N=136
S=136
E=150
W=122

TAS = 136
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@7500'

21/2350 (68%), 11.7 gph, OAT = 9dC.

N=125
S=143
E=144
W=124

TAS = 134
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These speeds are at least 4kts faster than the speeds I saw with my old engine...even after installing the flap gap seals.

The book speeds at these settings are:

5500' = 135kts

7500' = 133.5kts

And we all know that book speeds of this era were produced by the marketing department and not the engineering department.

I'll take 'em!

Timmy likes his new engine with Seth's tricked cylinders. :thumbsup:
 
Those are some good numbers Tim! Glad she's performing well!
 
I must've missed it, what kind of engine did you get installed?
 
FloridaPilot said:
I must've missed it, what kind of engine did you get installed?
Click to expand...

Just another run of the mill O470. But OH'ed by a reputable shop (Gann Aviation, Lafayette, GA) with six of Seth's trick cylinders on it.

As I reported last fall:

New OEM cylinders from a guy who isn't impressed with the quality factory work or their tolerances. A guy who will buy 12 cylinders for me, weigh them, keep the 6 closest matched and send the other six back. Then he'll port and polish, install new valve guides and hone them, rework the valves and valve seats, flow balance (for what that's worth on an O-470 with it's sh*tty induction system) blueprint and Cryo all parts. He'll also do a few things to the cylinders that I'm not allowed to repeat here! :D

Pap2fly.com

Seth's the man!

Both Seth and Carlus (Gann) do NASCAR work so their pedigrees ain't too shabby.
 
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Oh, and I really think I can squeeze a few more knots out of it yet by:

1. Repairing my "cowl intake to air filter" seal to obtain more "ram air" and thus (hopefully) increasing the MP a bit. Right now the seal is completely missing.

2. Playing with the induction system. Right now I have about 100dF spread in EGT. I played with my induction system on the last engine until it was regularly down in the teens...on a good day in the single digits. Amazing for an O-470.

3. Having the plane re-rigged. I've been wanting to do this for a few years now. Either John Efinger or Paul New. Paul's a lot closer.
 
Tim, that's great, thanks for the details. Earlier today I was doing some back of the napkin figuring; what capacity tanks do you have?

Also, do 182 drivers ever pull the power out when they are flying just for fun? I mean I can get well below 7 GPH fuel burn in my O300 172 if I don't mind flying 80/85 knots and 2300 RPM. The burn rate of a 182 just scares me. Yet there are times when I do some longer x-countries that 135+ kts would really be great, plus the power to climb higher, KTZR --> KBAF for example.
 
I have 65 gallons total, 55 usable, (59.5 if I dry tank in level flight). I plan no more than 4 hour legs. Tip tanks may be in my future if I keep working hither and yon. Flint internal tanks add 24 gallons, 2 hours, for about $8k installed. That's a lot of "speed" for the money.

And, yeah, I sometimes throttle back and fly low and slow, especially up and down the Mississippi on nice cool days (when it's not bug season). I can easily get the fuel burn down to less than 9 gph. Don't do it much other than that trip though.

Going high? I regularly flew my '57 172 @ 12,500 and it did fine. Granted, it didn't get there nearly as fast as my 182 does, but it got there. I used to flight plan at 105kts (not at 12.5k obviously! :) ) and almost always beat it by a knot or two. I "think" It burned about 8 gph in cruise, but it's been a dozen years...my memory is foggy. I miss that airplane, should've never sold it.
 
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timwinters said:
...engine was almost WOT (backed off just enough to close the "enrichment function"), leaned until rough, enrichened until smooth...
Click to expand...

Is that any different than just flying WOT and pulling back on the mixture a bit more? How do you know when the enrichment circuit closes, is it enough that it shows up in fuel flow?
 
GeorgeC said:
Is that any different than just flying WOT and pulling back on the mixture a bit more?
Click to expand...

Not really, it just avoids the engine stumbling badly and/or dying if/when the throttle is retarded later when you forget to enrichen first (I've had that happen a time or two, it really gets your attention!)

GeorgeC said:
How do you know when the enrichment circuit closes, is it enough that it shows up in fuel flow?
Click to expand...

What I look for is a rise in the EGTs (I have a full engine monitor). I pull the throttle just enough to see a rise but not so much that the MP lowers.

It likely shows up on the fuel flow too...I've just never looked. I'll have to check it out next time.
 
so....how much extra HP does it take to go an extra 5-10 kts than book speeds? :D
 
I've been kicking myself for not thinking to check the accuracy of the ASI while verifying TAS.

Dumb ass.
 
timwinters said:
Just another run of the mill O470. But OH'ed by a reputable shop (Gann Aviation, Lafayette, GA)
Click to expand...

They're just down the road from us, when the time comes, if Carlus is still in the business he gets the job. I've heard nothing but great things about his work.
 
Bill Jennings said:
They're just down the road from us, when the time comes, if Carlus is still in the business he gets the job. I've heard nothing but great things about his work.
Click to expand...

Yeah, Lafayette. The locals pronounce it "laugh at it!" :)
 
GeorgeC said:
How do you know when the enrichment circuit closes, is it enough that it shows up in fuel flow?
Click to expand...

I just pull the throttle back until the MP needle wiggles. Down low, it's not far; at 8000-10,000 msl, it can be a third of its travel. Sunday afternoon at 7500 msl, 68°F, this gave me 147 knots true; book speed is 162 mph = 141 knots at 32°, less 3% power for high temperature.
 
Where's all the people screaming that flying a triangle or square pattern to get TAS isn't accurate enough?

PoA. You're slipping. I was expecting the usual.
 
I fly into the wind until I get slowest groundspeed, fly for a minute holding altitude and note groundspeed (GPS speed). Then I do a 180 and note groundspeed and average the two. And yes, calculate TAS using IAS and compare.
 
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