Brake Release to 10,000'

For those interested in real world climb numbers concerning RV-7A, gather 'round. I just landed and this is what I wrote down.

First off, here are the starting points.

OAT 81F, SL pressure 29.74, airport elevation 630'.
Aircraft gross weight = 1512 lbs, CG @ 83.2", take off fuel = 39.3 gallons.

Climb power from take off was wide open throttle. Rather than try to guess a best climb speed for the conditions, I decided to let the engine decide that. After take off, when rpm hit 2400-2500, climb was initiated at 110-115 KIAS. I maintained 2400-2500 rpm all the way up to level off. Also, the engine was leaned using the target EGT technique from a lead provided by hevans7a last evening. I used 1300F. Max CHT in the climb was 407F, oil temp never hit 180.

The Dynon timer was started as power came up for take off. Here's what happened.

Out of 2000 MSL - 1:31 minutes (913 fpm)
Out of 4000 MSL - 3:00 minutes (1123 fpm)
Out of 6000 MSL - 4:43 minutes (1130 fpm)
Out of 8000 MSL - 6:26 minutes (1142 fpm)
Level at 10,000 MSL - 8:27 minutes (1104 fpm)

The rates of climb have the airport elevation factored in and it must be noted - time is from standing still on the runway - conservatively one could subtract at least 30 seconds if times were measured from the initiation of the climb at 110 KIAS. I should have noted that time but did not. If it were as much as a minute, it would make a huge difference. Average rate to 10 grand would be 1252 fpm.

Density altitude at level off 11,810'

Fuel at level off = 37.2 (2.1 gallons burned to 10,000')

Total time of the flight 17:48 by the Dynon timer. Fuel remaining at shut down = 36.5 gallons (3.8 gallons up and down)

For sure a light weight RV-4 with 180hp and a CS prop will do much better. But all in all, it isn't that bad for 1500 lb + airplane on a relatively warm day with a fixed pitch prop.

Impressive

Very impressive David. I have followed your RV trials over the years and know you must be very happy with your RV now. I appreciate the regular documenting. I am one of many that benefit. Thank you.

Bevan
RV7A wiring

Target EGT

David, thanks for the write up, I too found the article on target EGT interesting. Just curious to know how you found adjusting mixture to maintain the target EGT. Did you get into a rhythm or did you need to "work" at keeping the EGT? Thanks for the write up it was interesting.
Mark Mercier
Vancouver, BC
C-GQRV RV-7A

teaguy said:

David, thanks for the write up, I too found the article on target EGT interesting. Just curious to know how you found adjusting mixture to maintain the target EGT. Did you get into a rhythm or did you need to "work" at keeping the EGT? Thanks for the write up it was interesting.
Mark Mercier
Vancouver, BC
C-GQRV RV-7A

Click to expand...

Mark,

It was easy. Just lean to 1300 to start and check it every minute or so. As you climb it starts reading something in the 1200's and lean ever so slightly to get it back to 1300.

I am not sure at this point how target EGT is determined, I need to look at the instructions again - 1300 was used because I think it is a safe number most any time.

Your target EGT sounds a bit high to me.. I would have expected to see it in low 1200s maybe even high 1100s.. But I understand that absolute EGT number will differ between different airplanes..

Radomir said:

Your target EGT sounds a bit high to me.. I would have expected to see it in low 1200s maybe even high 1100s.. But I understand that absolute EGT number will differ between different airplanes..

Click to expand...

If I don't lean at all, I see 1100-1200. That was during engine break in where they say, don't lean, and fuel consumption was totally gross, like 16-18 gph.

I got a private e-mail from a guy who seemed to know what he was talking about and he said he leans to 1300 and it is ok....that's my reference on the matter for now. For sure we need to lean a little in hot weather, even on take off.

Ah I see.. may be a misunderstanding then... "Target EGT" is a specific term that refers to something very specific and as far as I know comes from the GAMI guys and those Advanced pilot seminars.. That's what I refer to when I say "Target EGT" but sounds like you are referring to something else..

Where's 1300 in reference to peak EGT on your plane? Do you know how much ROP that is on *your* airplane?? You may be operating at a kinda bad place for your plane...

PS.. Never trust a guy who tells you to lean to a nice round (and random) number... expert he isn't..

Very interesting topic...and very confusing to a low time pilot like me! My first 100 hours as a pilot was leaning a Cessna 152 like they teach you - "until it gets rough, then a 1/4 turn in with the mixture".

My next 300 hours was behind a Rotax which doesn't require leaning at all! Why they don't make automatic altitude-compensating carbs for Lycomings, I don't know.

So, I've got 40+ hours on my new ECI 0-360 with a carb, 4 probes on both EGT and CHT. What is the simplest way to lean? Are there any "gotchas", like "don't do this unless you're above 8,000 feet?

Maybe I'm asking too much, but I really want some way to lean effectively without having to do math while I'm flying.

Radomir said:

Your target EGT sounds a bit high to me.. I would have expected to see it in low 1200s maybe even high 1100s.. But I understand that absolute EGT number will differ between different airplanes..

Click to expand...

If I run in the 1100's, I can usually count on fouling some plugs, which need to be cleared during the mag check. Most flights are from 7500 to 9500' msl, since it's mountain country around here. 1325 has been my target for quite a while, and I haven't needed to clear plugs for a long time. CHT is usually around 325 in cruise conditions.

Now............ I have a carb, and only one cht & egt on cylinder #3. I know I'm now a "slacker", and a full engine monitor should have been about the #3 highest on my list. However, my #3 cylinder temps are quite consistent with others that have full monitors, that I fly with in this area.

What's a real kick, is if you search for LOP & EGT/CHT on the Internet. If you think that "what causes lift", or "pitch for speed or throttle for speed" is an argument, then you can occupy your self for a long, long time with the LOP arguments.

I've seen passionate arguments of using EGT for leaning, and not using EGT for leaning. Same goes for the CHT. I've also seen a writer who says's to not believe what a engine monitor company says in their operating book. And then of course, everything is different if you have fixed pitch versus constant speed...............according to some.

In the end, a reader can be confused as ever, since so many arguments are presented by those who seem in the know.

At the moment, I'll lean the old fashioned way, until the engine just starts getting rough. Then twist the red mixture knob in about 3 turns. This usually puts me at around 1250 - 1325 F. EGT. A long time flight instructor told me about the three turns, since I previously always used Piper type quadrants.

As to exactly where I am on the ROP/LOP scale, I don't know. And believe me; after reading ton's of material on this subject...............I still don't know! There are just far too many authors of information, with different ideas on this subject.

L.Adamson --- RV6A

Radomir said:

Ah I see.. may be a misunderstanding then... "Target EGT" is a specific term that refers to something very specific and as far as I know comes from the GAMI guys and those Advanced pilot seminars.. That's what I refer to when I say "Target EGT" but sounds like you are referring to something else..

Where's 1300 in reference to peak EGT on your plane? Do you know how much ROP that is on *your* airplane?? You may be operating at a kinda bad place for your plane...

PS.. Never trust a guy who tells you to lean to a nice round (and random) number... expert he isn't..

Click to expand...

I agree with Larry's comments. The subject of LOP ops is very controversial and it is chore sorting through it all.

To digress a bit on the subject of Target EGT, the term comes from the Advanced Pilot pps download. http://www.advancedpilot.com/assist.html

I looked at it again and what it says is the EGT you observe right after take off from a sea level airport on a standard day is the Target EGT. In the example they site, it is about 1325F. I did not know that until tonight. I used 1300 today because it seems like a reasonable number and it came from a guy I trust. It turns out Larry is using about that number out in Colorado and it works to keep plugs clean and burn less fuel.

The bottom line here is APS has defined a procedure many of us have been using informally for years. I have always leaned the engine just a bit right after take off, mostly to keep the plugs clean. Much of my early experience was with an 0235 in a LEZ and that procedure worked. I had an old rinky dink single egt gauge and just got it off the peg to start which probably was around 1300 degrees. In cruise it was lean to rumble and rich to no rumble.

Operating Lean of Peak (LOP) is another subject entirely. I have never done it because this is my first FI Lycoming. One can read anything one wishes to hear on the subject from "it is the only way to fly" to it is not recommended (by Lycoming). So take your pick. I am still studying the matter.

Radomir said:

Where's 1300 in reference to peak EGT on your plane?
Do you know how much ROP that is on *your* airplane?? You may be operating at a kinda bad place for your plane...

Click to expand...

Peak EGT is in the mid 1400's.

49clipper

David-aviator said:

Mark,

It was easy. Just lean to 1300 to start and check it every minute or so. As you climb it starts reading something in the 1200's and lean ever so slightly to get it back to 1300.

I am not sure at this point how target EGT is determined, I need to look at the instructions again - 1300 was used because I think it is a safe number most any time.

Click to expand...

David,
Target EGT is simply determined by a full rich takeoff and note the EGT on rotation (or thereabouts). Mine is approx 1200f on my -6 with O-320 carbed.
Good work, but how did you stay out of STL Class airspace. If I took off at SET, I cannot climb except in steps.
Jim

49clipper said:

David,
Target EGT is simply determined by a full rich takeoff and note the EGT on rotation (or thereabouts). Mine is approx 1200f on my -6 with O-320 carbed.
Good work, but how did you stay out of STL Class airspace. If I took off at SET, I cannot climb except in steps.
Jim

Click to expand...

I fly out of the Troy Air Park (02MO) not KSET. It is 28 nm west of KSET and just outside the Class B vail. We are 35.8 nm from Lambert.

Compare performance

Dave's data is very interesting to me, since I am planning my RV-7 project for an XIO-360, 180 HP, with a Cato 3 blade prop. I'm still in the planning phase and a number of my experienced friends have recommened I go to a constant speed, variable pitch prop instead of the fixed pitch.

Has anyone duplicated Dave's test in an RV-7 with an IO-360 with a constant speed prop. Theoretically the take off and climb rate should be better than Dave's, but how much better? The information might change my plan if it's significant.
RogerM
RV-7 QB, about ready to mount the engine.
Wildwood, MO

If you leaned to 1300 degrees F all the way to 10,000 feet, it is likely that you went LOP passing 7-8 thousand and and almost certainly were at 10,000 feet. That is what John Deakin recommends in his extensive articles on AvWeb on the subject. The way you did it (except for identifying your own target EGT), is the way he says to do it. According to Deakin, you can use that technique to regularly fly LOP on any flight if you go high enough. Just be careful to stay out of the "red zone" and you're not only fine, you are taking good care of your engine. Lycomings are tough engines and can stand a lot of abuse. But with a full featured engine monitor we now have MUCH more control over them than we ever had before. Lean until "she runs rough" worked well enough for decades, but we can do much better than that now.

Regards,

Lee...