Flying by the numbers

[Freight Dog]

 

I came across these figures while looking through MAPA Pilot Proficiency manual. I'm just wondering what you guys think about these performance numbers... a little too optimistic? Spot on? Way off? 

 

[orionflt]

I have reviewed that same chart and on my C model the numbers do not compare. The true airspeed are close but high, and I am usually burning 9.5 to 10 GPH to get those speeds. My usual fight planning is 135 kts, 10 GPH And I find 7-9000 ft seem to be the best altitude.

Brian

[mike_elliott]

These numbers are close for ROP ops. The TAS may be a bit off on a few of the models, like the E/F. For example, the E will be faster on any given configuration assuming they are both straight and properly rigged. The E just cant carry the same GW, have the same creature comfort nor have the endurance an F will, but this comes at a price of a few kts. for the F. The clean up of the F to the J overcomes this slight speed disadvantage.

LOP uses a multiplier of either 13.8 (low compression turbo motors) or 14.9 times the fuel flow to obtain horsepower. Divide this by the rated HP to get percentage. The MP+(RPM/100) doesn't work LOP. You can make up for the lost power percentage by safely adding back in Manifold pressure LOP, since your fuel flow will be less than the numbers on this chart typically

[Super Dave]

For hevier weights, the TAS looks good for our F with speed mods (although not the J cowl).

Those look like peak EGT fuel burn numbers for the F. So I see slightly lower numbers running LOP, and would expect around 15% higher than stated running ROP.

[jetdriven]

I have reviewed that same chart and on my C model the numbers do not compare. The true airspeed are close but high, and I am usually burning 9.5 to 10 GPH to get those speeds. My usual fight planning is 135 kts, 10 GPH And I find 7-9000 ft seem to be the best altitude.

Brian

You ought to be able ot get 140-142 knots at cruise, and 10 GPH seems a little rich also.

[FAST FLIGHT OPTIONS LLC]

<p>I'm seeing 155 KTAS @ 10K on my K&nbsp;with a FF of 9.5 GPH.&nbsp; Thats LoP between 60-65 percent power. (28&quot;/2450RPM). So I would say the chart is close for the 231</p>

[Hank]

My C runs pretty close to 9.0 gph block time; I have no fuel flow to check in the air, just knowledge from a self-calibrated dipstick on preflight and the pump at fill up. I also average pretty close to 140 kts. My longest E-W trip averaged 128 knots westbound at 8500, and 151 knots eastbound several days later at 9500. Routes were slightly different but not significantly so over 1320 nm each way. So I average 139½ knots. I'm happy.

 

P.S.--my C has 3-blades, 201 windshield and wingtips.

 

I generally fly using two or three standard settings from the book, but use the MP + RPM = 46 method for intermediate altitudes, step descents, etc. Normal descent is touch nothing but yoke and trim for 500 fpm and inch throttle back and mixture forward to maintain cruise settings until level off, then add to 46.

[DanM20C]

You ought to be able ot get 140-142 knots at cruise, and 10 GPH seems a little rich also.

I agree, I usually fly 9 to 11K, 2500rpm, wot, and see 140kts. My c model doesn't have any speed mods. Block to block I usually burn just under 9 gal/hr.  I flight plan 11gal for the first hour, and 9/hr for the rest of the flight.  It works out close that way and gives a slight margin in my favor.

 

 

Dan

[orionflt]

<p>I'm seeing 155 KTAS @ 10K on my K&nbsp;with a FF of 9.5 GPH.&nbsp; Thats LoP between 60-65 percent power. (28&quot;/2450RPM). So I would say the chart is close for the 231</p>

You ought to be able ot get 140-142 knots at cruise, and 10 GPH seems a little rich also.

I'm running a stock C model with no mods and the 180 hp engine, 135 kts is what I use for flight planning I probably get closer to 140 true burning around 9-9.5 GPH. I had to have my engine torn down due to my hanger doors falling in on the aircraft, we found that i had some worn cam lobes (i am sure that affected my performance) I also installed the MVP 50 engine monitor and have added the cowling mod so when I get back up in the air I will reevaluate my numbers, I am hoping for a substantial increase.

Adding a pic of my new panel.

[Freight Dog]

As a fairly new owner (not quite a year yet), I was concerned that I was perhaps overly leaning by '65 E. I routinely fly 21"/2400rpm and about 9.5 - 9.8 gals on JPI450. 
 

This document said I should expect 9 gph even as that's 65% of power, but I was a little leery of overly aggressive leaning. Now I'm starting to think I was still running it significantly rich. 

[Parker_Woodruff]

Turbocharged engines are so much more altitude dependent for TAS.

 

11.6 gallons per hour would get me in a range from 160 KTAS to 195 KTAS depending on how high I used such power settings.

[Marauder]

I'm running a stock C model with no mods and the 180 hp engine, 135 kts is what I use for flight planning I probably get closer to 140 true burning around 9-9.5 GPH. I had to have my engine torn down due to my hanger doors falling in on the aircraft, we found that i had some worn cam lobes (i am sure that affected my performance) I also installed the MVP 50 engine monitor and have added the cowling mod so when I get back up in the air I will reevaluate my numbers, I am hoping for a substantial increase.

Adding a pic of my new panel.

 

Howdy Neighbor. Love the panel!

[Marauder]

I think you will find that there are a lot of variables that influence what any particular plane will do. And I think it is difficult to nail a specific number for a model class. My 75F has a 201 windshield, flap & aileron gaps seals and the lower cowl enclosure. I file 150 knots and 10 gph but do closer to 155 at 9.8 gph ROP.

 

I think rigging is an area that robs speed pretty quickly. Whether it be gear doors dragging, flaps partially extended or just mis-rigged. Engine wear and tear also probably plays a role to some extent. And then are some planes that are just plane quick.

[orionflt]

Howdy Neighbor. Love the panel!

Thanks,

I have way to many hours into this upgrade, just glad I don't have to pay anyone for all the time invested. When the interior arrives and I get it installed I will post pics.

[Marauder]

Thanks,

I have way to many hours into this upgrade, just glad I don't have to pay anyone for all the time invested. When the interior arrives and I get it installed I will post pics.

 

It's addicting... Like plastic surgery is for Joan Rivers.

[M20F]

I have 67 M20F and it comes pretty comparable to the numbers Dave McGee did in his report though for whatever reason we were way off at the low altitudes:

 

4500 they got 151.25 I got 140 which is 7.44% off

7500 they got 150.5 I got 144.7 which is 3.82% off

10000 they got 145.25 I got 141.25 which is 2.75% off

10000 I get 145 versus 145.2 when I put in the rayjay and go up to 75% power

 

http://www.mooneypilots.com/mapalog/M20F%20Evaluation/M20F_Evaluation_Report.html

 

Remember numbers never lie, liars figure...

[orionflt]

I flew a friends F model up to Maine and back this past weekend, I was @9500 and about 65% power. The numbers seem to match the chart pretty close. Not sure about the fuel burn, mine was higher then chart but that was the average for the flight and I did shoot a couple of landings before I left on the trip.

[scottfromiowa]

There are so many variables....What was weight of plane.  I took off at gross yesterday and flew at 2500 feet with fuel burn of 9.1GPH.  NOWHERE NEAR 145knots.  I was 130 tops (groundspeed) and that was/is just fine. 

 

You guys with your 150+knot C,E,F's...ENJOY.

[47U]

Weight makes some difference.

 

Two weekends ago, I was between Marysville and Chico and did some speed runs, 2400 rpm and 20 inches and another run at 24 squared.  I was at 5,000 msl and it was a little warmer than standard at 63 degrees.  I was at about 40 gallons and by myself (another 230 "or so" pounds).  Oh, three bladed prop.

After flying the four quadrants and averaging out the GPS ground speed, it turned out to be 127.25 kts at 20" and 144.5 kts at 24"... my fuel flow is out of service so I'll have to check that another day.  All in all, sitll pretty good for a '63 Mooney Bird with mid-time motor.  She turned 50 this month. 

Here's my chicken scratches...

 

[vorlon1]

This thread is of particular interest to me since I am starting (what will be a slow process) to look for a good example for my first plane.  My target is 150 @ 10gph, and there are several makes and models that will do this, Mooney's chief among them.  Thanks for keeping the postings coming!

[Jerry 5TJ]

I get 135 ktas heavy and 140 ktas mid-weight at "47" aka ~70% power. About 9 gph, so i see close to the MAPA charts' numbers.

Flew a PC12 / 45 yesterday, 262 ktas FL220 63gph, exactly per book. How come their POH is gospel and we vintage Mooney drivers can't agree within 10%? Is it that our half-century-old planes are all now unique?

[scottfromiowa]

I should have punched up the power percent on my G3.  I was down low and being conservative on MP.  I was definitely below 70% and probably below 60% as I was about 2450MP 2500RPM and leaned to 9.1GPH at 2500 on that run.  It was flashing back and forth between 50LOP to 50ROP so was probably close to peak exhaust temp at this fuel flow.  No ram air pulled on this flight down low.

 

I always say I am going to do compass cardinal GPS run....but I never do.

[canuckpilot]

This thread inspired me to try a speed run.  I'm sure I screwed something up with my methodology, but attached are snapshots of the panel at the various cardinal headings.

 

Airplane: 1965 M20E with most speed mods, but not the 201 cowling.

Altitude: 7,500 ft

OAT: 72F

Throttle: WOT - 23" (ram air on)

RPM: 2600

Mixture: 100ROP

Weight: around 2,100 lbs (475 lbs below gross)

Overhead vent: closed

Thinking: speedy thoughts

 

Results:

east: 157kts

north: 164kts

west: 167kts

south: 164kts

 

average: 163kts

 

I wasn't terribly good at doing the various headings in quick succession, so the winds may have shifted.  JPI says I was burning 12.8 gl/hr trying to go balls to the wall...  I usually cruise in the 9,500 - 11,500 range getting at around 155kts for 11gl/hr (100 ROP) 

 

POH says I should've been making around 191 mph (166kts) at the above settings (though at best power, not 100 ROP - and in standard atmospheric conditions)  so I guess I'm within the POH's ballpark - but that's after the speed mods.  I have a hard believing that the plane performed per the POH back in 1965...

 

Cheers,

 

-matty.

 

 

[Bob_Belville]

I normally run my '66E @ ~65%. I have an Aspen that displays TAS and a JPI 930 that display fuel flow and %HP so I don't have to fly boxes or calculate.

 

7/20/2013 @ 7000', 21.5/2450, 66% 10.5 gph,           OAT 17C = TAS: 171mph =  149 k (cowl flaps open, roof vent open)

  and         @ 9000', 21.2/2450, 64%   8.6 gph (LOP) OAT 12C =          168mph =  146 k (cowl flaps closed, roof vent closed)

 

We were near gross weight. (The cowl flaps kept the OilT around 200 on the 7000' portion. The roof vent kept Nancy near 98.4. Each drag is worth a knot or 2.)

 

We have all (except inner gear doors) 201 mods plus Powerflow exhaust.  

[pinerunner]

As a fairly new owner (not quite a year yet), I was concerned that I was perhaps overly leaning by '65 E. I routinely fly 21"/2400rpm and about 9.5 - 9.8 gals on JPI450. 

 

This document said I should expect 9 gph even as that's 65% of power, but I was a little leery of overly aggressive leaning. Now I'm starting to think I was still running it significantly rich. 

You're right, you almost certainly are running it rich. With my 65 E 9.5 GPH at 23 inches and 2500 PRM has all but #3 ROP and #3 just going over peak EGT. So 2 inches lower manifold  and 100 RPM less should certainly be rich. At such a low power setting you probably don't need to worry about detonation but I wonder that you don't know if you were LOP or ROP.

 

Could it be you don't have an EGT/CHT engine monitor. Not just for leaning but even more for the diagnostic power (like catching bad valves early) I think its the most valuable upgrade you can get.  At low power setting you don't need to be leery of over-leaning, unless you don't want to run too cool. I don't mean to rag on you but I'm a big fan of the modern engine monitor.

 

Dave