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performance

DeltaVee47

Active Member
Happy New Year
I am now out of phase 1 flight test and would like to compare my performance data with others but cannot find much posted so far. I found one post from 3 years ago but if there are others I would appreciate being pointed in the right direction.
I will submit my basic numbers so far but I have no idea if they are good/bad or indifferent.
I am flying the stock 390/Hartzell 2 blade with dual pmags, jumpers in and timed as per Brad's expert instruction. Using the Garmin lean assist in the G3X system. My speeds are low because I don't have all my gear fairings finished yet. When I have to choose between building and flying well you can guess which wins out if the weather is halfway decent.

6500 ft OAT 50F 23/2300 25 LOP 10.2 gph 154 kts, oil temp 190 and CHT's
320's
6500 ft 23/2300 50 ROP 11.2 gph 160 kts. chts 330's but
oil temp creeps up to 200
6500 23/2400 25 LOP 10.7 gph 158 kts all temps fine
6500 23/2400 50 ROP 11.7 gph 162 kts chts fine, oil temp
205

I'll stop there but I have way more where that came from.
The fuel consumption seems higher than what I was expecting.
I'm a little worried about the oil temps when running ROP.

Thanks in advance
Greg Beckner
N557GB
 
I've posted a few screenshots of performance on my blog (see signature). Today was a good example: 24", 2400 RPM, 172-173 Kts, around 9.8-9.9 GPH LOP at 6500 feet.

The higher you go the more efficient the airplane is. I had a tuning session with Airflow Performance a few weeks back to improve efficiency as well: I wasn't really able to get LOP without some roughness prior to that.

Oil temps run a bit higher with the IO-390 than many other Lycoming models but CHT's tend to be lower in the -14A. My understanding is that this is a result of using oil to cool the cylinders but no engine expert myself.
 
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You can expect upwards of 20kts TAS improvement with all of the pants and fairings on. My 14A was in the mid 150's until I put on the pants and fairings.
 
Unless you have calibrated your fuel flow computer by running a few tanks of fuel through it and resetting the K-factor appropriately I would not consider the current reading an accurate representation of actual fuel flow...
 
Unless you have calibrated your fuel flow computer by running a few tanks of fuel through it and resetting the K-factor appropriately I would not consider the current reading an accurate representation of actual fuel flow...
I agree and would add that the TAS also need to be verified for accuracy.

I can't really comment on the performance number since you don't have the wheel pants on.

As a reference, my typical LOP at 22" and 2500 RPM at 8500' is around 8.3GPH and 162K of TAS. As you go higher, the fuel burn comes down and TAS remains about the same. My most efficient burn rate is around 17/17.5K and I burn 7.5G at 160k. On a x-country trip, it is 8GPH ramp to ramp if I go that high.
 
Thanks all
Yes I?m posting TAS. At the risk of appearing dumb I?m not sure how to verify TAS other than running the numbers through my old E6B.
Calibration of the fuel flow computer is an interesting idea. Could you elaborate on how this might be done? The totalizer seems to be accurate within one gallon in 25 if that means anything.
I?m not that concerned about the speed numbers so much as the fuel burn. As an aside I note that I am not getting 24 inches MP at 6500, full throttle I?m seeing about 23.6.
The suggestion about Airflow Performance is very welcome.
Greg
 
Thanks all
Yes I?m posting TAS. At the risk of appearing dumb I?m not sure how to verify TAS other than running the numbers through my old E6B.

The best and easiest way I know is to use the three way GPS run and record the heading and GS. Fly North and record your GS, then West and record the GS and then East and record the GS.

I have the XLX sheet with the formula but can't remember how I set it up.
If you like you can send me your numbers and I plug them in or send me your e-mail address and will send the xlx sheet to you.
 
The best and easiest way I know is to use the three way GPS run and record the heading and GS. Fly North and record your GS, then West and record the GS and then East and record the GS.

I have the XLX sheet with the formula but can't remember how I set it up.
If you like you can send me your numbers and I plug them in or send me your e-mail address and will send the xlx sheet to you.


Why 3 way versus 4 directions? I would like a copy of your XLX sheet.

Thanks
 
Hey Greg---at the risk of getting flamed here---because I dont have a flying plane---I think worrying about TAS and all the other stuff is somewhat irrelevent right now. Get the fairings, wheel pants and any other drag reducing items FINISHED and installed in their final configuration before worrying about what the TAS will be ---should be as compared to other "like equipped" aircraft.
WE know of many builders that made some changes, improvements (they thought) that actually slowed things down.
Get the plane to a more finished point--then start your comparisons. As you'll find out, you'll always be working on something to "improve' your plane, and not all of them will make it faster, or lower the fuel consumption.
Just my 2 cents worth.

Tom
 
Why 3 way versus 4 directions? I would like a copy of your XLX sheet.

Thanks

The 3 directions should form a triangle. Not just 3 directions. An EFIS with gps inputs makes things even far easier than doing this:

Go straight into the wind. Wait for speed to stabilize. Record GS, TAS, and wind.
Do a 180, and record the same. The GS, TAS, and wind should be the same. If not you probably have a pitot static error.

The only "measured" value is GS. TAS and wind are calculated. The easy indication that tells you something is amiss is the wind has changed significantly.

If you need to do a 3 way, it needs to be a triangle. By that I don't mean a geometric triangle over the ground, but 3 headings/legs that form a triangle.

And yes, it can be don't with just 3 headings that don't form a triangle, but the math gets a lot harder.
 
The 3 directions should form a triangle. Not just 3 directions. An EFIS with gps inputs makes things even far easier than doing this:

Go straight into the wind. Wait for speed to stabilize. Record GS, TAS, and wind.
Do a 180, and record the same. The GS, TAS, and wind should be the same. If not you probably have a pitot static error.

The only "measured" value is GS. TAS and wind are calculated. The easy indication that tells you something is amiss is the wind has changed significantly.

If you need to do a 3 way, it needs to be a triangle. By that I don't mean a geometric triangle over the ground, but 3 headings/legs that form a triangle.

And yes, it can be don't with just 3 headings that don't form a triangle, but the math gets a lot harder.

Additionally, to get accurate data, the heading reference must be accurately calibrated (I.E., magnetometer calibration.)
 
Another RV-14A flying

With all of almost 10 hours on the airframe today was the first day I inserted a SD card into the 3GX. Back ground on airframe:

Lycoming 390 Thunderbolt, Whirlwind 3 blade CS prop, EFII ignition and fuel. Idles dead smooth, hard to tell when the engine is running vs starter engaged, need to look at the RPM's, (650 RPM, I know a little slow)

I try to vary the MP and altitude but on a fairly long constant run today here they are:

22.4 " MP
11.3 C OAT
7,300 ft. MSL
170 knots TAS
187 F Oil Temp
324-345 F CHT
1295 - 1315 F EGT

No fuel flow reading as yet as I have not calibrated my fuel management system.

Did not do the triangular right test, that can be next. Have a funny whine at 170 knots and above, might be the gap seals, might be the oil cooler flapper. Still looking.

RV-14 is a very nice ride !!
 
Most of the whines described on here have been canopy seals. Unless you count random complaining....
 
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