Speed for an E Model

[flight2000]

**Please don't take this as me boosting about on the speed of my aircraft as that's not my intent, I'm just curious to find out what others are seeing in their aircraft after seeing a wide spread in E models from another list and to see if I'm doing something out of the ordinary.  I've only flown her about 8 hours so far (due to weather and finally going to the avionics shop for upgrades).

Question for my fellow E owners.

Is my bird that much more different in the fact that I can routinely get 155 kts indicated at 3500 ft and 25 squared?  I haven't had the opportunity to go higher yet because of the shorter trips I've been taking and the class B that sits over my airport. 

The ferry pilot that brought up my plane from Texas in December told me he was seeing 160 kts indicated at 7,000 ft (he's a 201 owner).  The only mods I have on the plane are the 201 windshield and the lower cowl enclosure (unless you count the GAMIs that are installed as a mod as well).  I'm only seeing fuel burn around 9-10 gph so I'm not burning the tanks up seeing these speeds.

Thoughts?

Thanks,
Brian
'67 E Model

[flight2000]

Sorry, double post.

[rob]

I think that either your ASI is malfunctioning or you're misreading it (might it be in MPH?). The speeds mentioned, especially 160k IAS at 7000 are significantly faster than you should be. I don't think ANY NA Mooney is that fast... (You're talking about a 180kt true airplane)

Additionally, it makes no sense for you to indicate 155kts when your ferry pilot indicated 160 at twice the altitude. IAS should decline as altitude goes up.

[eaglebkh]

I plan for 140kts TAS at 24-24 in the 5-9k arena (with ram air on where needed), which is easily attainable.  I have no speed mods.  Admittedly, I've never really done any runs at 25-25, but I would expect 145-148kts.  I could see where the 201 windscreen and cowl closure could equal up to 10kts, maybe.  But I'm talking true here, not indicated, which Rob highlighted the difference.

Here's a recent flight picture and an opportunity to show off the Aspen.  Notice the speeds in the window below the airspeed tape.

[flight2000]

My ASI is in MPH on the outer ring and KTS on the inner ring and no I'm not misreading it...   Never thought about the ASI being out of calibration, so I suppose I'll have the avionics shop check it while it's on the bench.  I don't think it is though because rotation speeds are where they are supposed to be and same with landing.  If it's to far out of whack, I really need to be concerned, especially at low speeds.

The photo attached shows where I was at and at the time I was in smooth air so I went 26-26 just to see.  No concerns as she purred right along and was perfectly happy.  The GPS showed 183 kts groundspeed, the forecast had winds at that level almost to my back and 20-25 kts.  I haven't seen any outragous fuel burn at those settings either. 

Brian

 

[flight2000]

Okay, I give.  Is there a super secret way of attaching a photo?  I've tried the attach photo button and it keeps blanking out without attaching anything.  Frustrating....

In the mean time, I added the photo to my gallery.

[rob]

If the GPS showed 183 groundspeed and you had 20-25 behind you, then you're doing 160 or so TAS. At the altitude you're referring to, I'd expect to indicate about 145-150 if I was doing 160 true. Your picture, though, shows an IAS of 160, and a GS of 183. At 3500' that would be about 170kts TAS, so the winds would have had to have been 10-15 behind you instead of the 20-25.

You appear to be in a descent from the photograph taken.

 

[flight2000]

I was in level flight, might have been the angle of the camera as it was up higher than eye level.  I was snapping and trying to keep an eye on everything at the same time.

The wind was a guess based on the forecast and not actual speeds. 

Brian

[Magnum]

I'd suggest to fly 4 directions, each 90 degrees apart and measure the speed with the gps. Calculate the average and you have TAS. With the 496 you can calculate IAS easily and then you'll know if your ASI is ok. My ASI had an error of approx. 3-4 kts up to 90 kts IAS, at 160 kts IAS the error was around 20kts (but the other way around, it showed lower than actual). Hope that helps.

[airkraft]

Brian,

I agree with Magnus.  Fly N,S,E,W several times and average the ground speeds from your 496.  This will get you very close to actual KTAS.  I would suggest doing so at 9,500 and 10,500 feet, full throttle, 2,500RPM, 30-100 degrees rich of peak EGT.  This is where I find the fastest true air speeds in my similarly modified (and painted, for that matter) E model.  I have the SW Texas windscreen, but no cowl closure. I do have the blended (scimitar) 2 blade Top Prop.

I've never cruised lower than 8,500' so I do not know what TAS or IAS is at the lower altitudes.  Your speeds do seem unusually high, though.  I see maximum TAS in the 150-157KT range depending on aircraft weight and density altitude.

 

[drpep]

I also own a 67E WITH A 201 WINDSHIELD AND A LOWER COWL MOD.  I a four direction GPS ground speed check and average out at 144kts

Philip 

[drpep]

I also own a 67E WITH A 201 WINDSHIELD AND A LOWER COWL MOD.  I did a four direction GPS ground speed check and average out at 144kts

Philip 

[airkraft]

At what altitude and power setting, Philip?

[Piloto]

The picture clearly shows the plane to be pitch down, just look at the horizon out the windshield. Also the fact that the left thumb is pressing against the yoke, not to mention the VSI reflection indicating -1200fpm.

José

 

[flight2000]

Quote: Piloto

The picture clearly shows the plane to be pitch down, just look at the horizon out the windshield. Also the fact that the left thumb is pressing against the yoke, not to mention the VSI reflection indicating -1200fpm.

José

 

[knute]

Another data point:

1966 M20E with 201 windshield (SWTA), cowl closure (ARI), flap gap seals, wing root fairings and MT 3-bladed composite prop.

Full throttle, RAM air open (I don't remember the actual MP and don't have the log notes at my fingertips) at 2500rpm, 100 ROP, 10-25 celsius OAT, 7500-8500 ft MSL, I will typically see between 153-158 knots TAS based on a four-way GPS ground speed average with light winds.  I have done this test a number of times out of curiosity to find out the magnitude of the speed difference I get from varying gross weight and OAT.  20-30 LOP at the same altitude drops me down to 143-147 knots TAS or so, and is smoother if the RAM air door is not quite fully open, which gives up another fraction of an inch of MP.  (Something I read about more turbulent intake air helping the distribution?  Works for me.  GAMI spread is 0.2-0.3 gph between first and last to peak)

The 201 windshield is new, and added about 3-4 knots.  The MT 3-blade prop replaced the original Hartzell 2-blade, and depending on which data I look at from my records the MT is about the same speed or maybe 1 or 2 knots slower when down low, less difference with altitude, and improved climb between 100-200fpm.

If I wash the plane and wax it, I will pick up 2-3 knots compared to "not been washed in a while with some bugs on the leading edge and oily dust on the belly".

Hope that helps!

We pride ourselves in having fast airplanes, and it's fun to compare numbers.

-Knute

'66 M20E - N6066Q - KSQL (San Carlos, CA)

[Piloto]

The picture was taken at same elevation as the glareshield cover so in level flight the horizon will just appear at same level. But when you dim the computer monitor the horizon appears to be 5 deg above the glareshield. Which matches with the ADI. If you were in level cruise flight with A/P on why would your left thumb be pressing on the yoke. The VSI reflection is from the pilot's sunglasses visible on the altimeter glass. You need a photo enhacing software to see this.

José

   

[flight2000]

Quote: Piloto

The picture was taken at same elevation as the glareshield cover so in level flight the horizon will just appear at same level. But when you dim the computer monitor the horizon appears to be 5 deg above the glareshield. Which matches with the ADI. If you were in level cruise flight with A/P on why would your left thumb be pressing on the yoke. The VSI reflection is from the pilot's sunglasses visible on the altimeter glass. You need a photo enhacing software to see this.

José

 

[eaglebkh]

Quote: Piloto

The picture was taken at same elevation as the glareshield cover so in level flight the horizon will just appear at same level. But when you dim the computer monitor the horizon appears to be 5 deg above the glareshield. Which matches with the ADI. If you were in level cruise flight with A/P on why would your left thumb be pressing on the yoke. The VSI reflection is from the pilot's sunglasses visible on the altimeter glass. You need a photo enhacing software to see this.

José

 

[drpep]

Lots of spirited dialogue on this issue... While I am very much interested in speed my primary interest is in comfort and my plane's flying attributes at different speeds. AsI previously mentioned in my 67 super 21 I saw 144 kts gd speed from my GPS averaged over four directions based on wind direction at 2500 feet . Since I live near Vancouver Canada my flights tend to be between 2500 and 4500. I do journey to the interior of BC across the Rocks  between 10 and 12 but I have yet to check on the airspeed as I have been to focused on getting to my destination . Given the the comments so far I am stimulated now to check at other altitudes such as 4500 and 8500. When I can I will do so. I tend to run 50 ROP at 24 squared. i have not yet factored in Ram Air. Similar to  Knute, I have a three blade prop only it is a Hartzell. I will post new data as it becomes available

Thanks all

Philip  

[KSMooniac]

The simplest explanation is that your ASI has a major error, or else your fairly stock E is somehow much faster than every other 200 hp Mooney ever made.  Sorry to rain on your parade!

You might inspect your static ports on the fuselage aft of the cabin.  Check to see if they're sitting flush with the skin, and the skin is not distorted.  I've heard that an old used-airplane salesman trick is to "tweak" the static ports by sticking a small punch into the opening and bending it aft, which will make the ASI read higher.  Perhaps you have a partially collapsed static line somewhere inside the cabin, which might cause the same effect.  When you do a GPS calibration run you'll discover how far out it is.  (PS, you can also do a 3-way run on headings 120 degrees apart, then take the square root of the sum of the squares and not do a 4th run.)

[eaglebkh]

Quote: KSMooniac

(PS, you can also do a 3-way run on headings 120 degrees apart, then take the square root of the sum of the squares and not do a 4th run.)

[KSMooniac]

oops!  I mis-remembered or typed too fast and skipped a step!  :0

The squares of the three readings should be AVERAGED, then take the square root of the average.  Also, I said headings should be flown 120 deg apart, but it actually should be TRACKS.  This can be done using a 430, a user waypoint, and the OBS mode to establish tracks to follow, vs. headings to hold.

[rob]

Averaging any number of legs will be less accurate than the method KSMooniac is advocating. However, both will be close enough for the girls I go out with if you include at least three legs. Additionally, no accurate method will show a NA E model doing 180kts.

[flight2000]

Quote: KSMooniac

The simplest explanation is that your ASI has a major error, or else your fairly stock E is somehow much faster than every other 200 hp Mooney ever made.  Sorry to rain on your parade!

You might inspect your static ports on the fuselage aft of the cabin.  Check to see if they're sitting flush with the skin, and the skin is not distorted.  I've heard that an old used-airplane salesman trick is to "tweak" the static ports by sticking a small punch into the opening and bending it aft, which will make the ASI read higher.  Perhaps you have a partially collapsed static line somewhere inside the cabin, which might cause the same effect.  When you do a GPS calibration run you'll discover how far out it is.  (PS, you can also do a 3-way run on headings 120 degrees apart, then take the square root of the sum of the squares and not do a 4th run.)