Improved speed documented

[Mooneymite]

47 minutes ago, David Lloyd said:

There does seem to be a lot of variation from one airplane to the next.  Same model, same mods, same fuel flow, different speeds.

My '74 C has no speed mods.  It delivers pretty much the performance numbers in the owners' manual....consistently.

Whenever I read about "fast" unmodified Mooneys, I'm somewhat suspicious of the data methodology of the reporter.

[gsxrpilot]

14 minutes ago, steingar said:

I wish I could say I was flying the fastest C, it just isn't so.  I might have been able to say I flew the prettiest, but Bob Belville has me pretty badly beaten in that category as well.

@Bob_Belville flies an E... so you're still in the running for the prettiest C 

[Bob_Belville]

Bob's cowling started as an ARI, didn't it?  Maybe your cowling is comparable to the ARI in aerodynamics. 

Just my $.02, I don't have any real proof.


I think that’s a good point. In my case I think the CHTs are more uniform and perhaps slightly lower than before. And@sabremech is correct, my OilT issue did not start with the new cowl.


Sent from my iPad using Tapatalk

[David Lloyd]

29 minutes ago, Mooneymite said:

My '74 C has no speed mods.  It delivers pretty much the performance numbers in the owners' manual....consistently.

Whenever I read about "fast" unmodified Mooneys, I'm somewhat suspicious of the data methodology of the reporter.

The owner's manual for the '65 C Model I had, the performance numbers were wishful thinking at best.  The older books are on this site.  Don't read with a mouthful of coffee.  The increased speed claims of the "speed" mods I installed were seriously overstated. That's why I'm asking, what does work and by how much.

[Mooneymite]

29 minutes ago, David Lloyd said:

The owner's manual for the '65 C Model I had, the performance numbers were wishful thinking at best.  The older books are on this site.  Don't read with a mouthful of coffee.  The increased speed claims of the "speed" mods I installed were seriously overstated. That's why I'm asking, what does work and by how much.

I understand your intent.  My point is that as unreliable as the older performance numbers may be, the "reported" numbers by Mooneyspacers may be equally wishful/optimistic.

Who are you going to trust?  

[Marauder]

A couple of my pals are touting the LASAR cowl closure mod.  Closes off the bottom of the cowl, improves airflow.  They're claiming several knots for 0.5 AMUs, and I have to admit one of the guys who did this easily keeps up with Js in his E, and I don't think it had that much more done to it.  Any other experiences?
I wish I could say I was flying the fastest C, it just isn't so.  I might have been able to say I flew the prettiest, but Bob Belville has me pretty badly beaten in that category as well.

I had a few hundred hours in my F when I did the cowl mod upgrade back in the 1990s. The net increase in airspeed was about a knot. What it did do for me was bring up my CHT temps from the high 200s’ to the low 300s’. This was an issue flying in Buffalo since it was getting too cold.

My F has the 201 windshield and gap seals. I flight plan 150 KTAS but will typically see 152 KTAS with normal ROP leaning. As was mentioned above, if I run aggressive power settings with the associated fuel flow, I can get her to fly at 156 to 158 KTAS but at 13.5 to 14GPH.




Sent from my iPad using Tapatalk Pro

[Marauder]

That 160 KTAS was running close to 15 GPH at 2600 and full throttle.

Speed costs money...


Sent from my iPad using Tapatalk Pro

[MBDiagMan]

12 hours ago, MyNameIsNobody said:

What is the fuel flow.  I can’t read it.

.... and wind conditions....

[MIm20c]

1 minute ago, MBDiagMan said:

.... and wind conditions....

The Aspen has a TAS display which some feel is slightly inaccurate...worlds better than “feel” IMO. 

[MBDiagMan]

Whoops!  I didn’t notice the TAS next to it.  On the 430, the TAS display is nothing more than a calculator.  You could enter whatever numbers you choose to obtain whatever TAS.  Hopefully the Aspen is more automated than that.

[rbridges]

My C model has every speed mod that I can recall--201 cowl/windshield/powerflo exhaust/gap seals/ VOR antenna moved to wingtips, etc.  I've been watching the speeds for years, and I believe it's a true 150-152 knot plane.  Nothing scientific, but I adjust the ASI for altitude and temp.  I also compare GS on the GPS with reported winds aloft.  It's a little heavy; I bought it with a 870ish lb useful load, so that may explain why Paul's C was just as fast without the cowl.

[Stephen]

13 hours ago, mike_elliott said:

8.5

... the ball is slightly off center. One of the ailerons is tweaked some per dmax

.... maybe that is why it is so fast.... the tweaked aileron slipstream interaction with the Coriolis effect causing a precession deflected sinusoidal pressure wave to impact the trailing edge of the elevator resulting in net thrust and a coincidental harmonic drop in induced drag...

 

This video explains it all...:

https://www.youtube.com/watch?v=MXW0bx_Ooq4

 

 

[mike_elliott]

Just now, Stephen said:

.... maybe that is why it is so fast.... the tweaked aileron slipstream interaction with the Coriolis effect causing a precession deflected sinusoidal pressure wave to impact the trailing edge of the elevator resulting in net thrust and a coincidental harmonic drop in induced drag...

 

This video explains it all...:

https://www.youtube.com/watch?v=MXW0bx_Ooq4

 

 

I have actually seen 160 TAS on 8.3 GPH, but I didnt take a pic, so I guess it didnt happen.

[Stephen]

Just now, mike_elliott said:

I have actually seen 160 TAS on 8.3 GPH, but I didnt take a pic, so I guess it didnt happen.

I'm sure it did, my point was more ...whatever is going on with your J, it is impressive and obviously working (not intended as tongue in cheek,) .. ! I've seen numbers with my F that are somewhat close such that if I had some of the aero cleanup of a J I could see you getting those numbers. 

[Marauder]

The Aspen has a TAS display which some feel is slightly inaccurate...worlds better than “feel” IMO. 

The Aspen’s calculator is accurate as a calculator. It has a dependence on the information being fed in from the GPS and its own airspeed. What the true CAS is for these electronic gizmos will always be a question. Since I have another electronic gizmo (ESI-500) showing airspeed, I have plugged everything into the GTN and verified I am getting the same numbers as the Aspen.

The CAS will change this by a knot or two. So, does the difference between 160 and 158 really make that much difference?


Sent from my iPad using Tapatalk Pro

[Marauder]

Whoops!  I didn’t notice the TAS next to it.  On the 430, the TAS display is nothing more than a calculator.  You could enter whatever numbers you choose to obtain whatever TAS.  Hopefully the Aspen is more automated than that.

The Aspen uses the winds, ground speed from the GTN, its own airspeed and altimeter to come up with the TAS.

I have been flying behind the Aspen for 6 years. The TAS has always been within a knot of any multi-leg speed checks I have done.


Sent from my iPad using Tapatalk Pro

[DXB]

My datapoint w/ detailed info.  

Aircraft: 1968 C model

Cruise speed: 147 kts, most typical speed observed over 500hrs of flying (not transient best speed seen during atmospheric phenomena)

Method for determining airspeed: TAS on Aspen PFD, minus 2-3 kts (Aspen doesn't account for CAS correction)

Altitude: 7000-10,000ft

Power settings: 25k rpm, just shy of WOT, carb heat cracked slightly open

Fuel flow: 9-10gph

Mod from stock - potential speed benefit:   (1) flap gap seals - slight (2) brake reversal - slight (3) Lasar cowl closure - likely none (4) LASAR 201 wing tips - likely none (5) Hartzell Top Prop - dunno (6) Knisley Exhaust -dunno (7) Millennium cylinders - likely none

Comments

-I listed mods that the plane came with above.  I added the LASAR 201 type windshield after flying it for 200 hours and honestly didn't see a clear increase in speed, though the cabin is noticeably quieter and the extra visibility is nice.  

-My C seems conclusively faster than a typical stock one by 3-4kts, but it is not among the fastest.  I've no clue which if any of the mods account for the improvement. 

-I hope to get the illusive 150kt with the Sabremech cowl.

[ArtVandelay]

yea, its amazing how fixing the baffle seal solved that.

But it will now be slower, might explain some of your past performance.

There is something called cooling drag, if you watch a NASCAR race, they will duct tape the radiator air intake at times on the super speedways.

Personally I’ll take a speed penalty to keep my engine cool.

I’ve wondered if we airfoiled the push tubes and some other cleanup what kind of speed advantage you would get.

[Marauder]

Another datapoint. AirMods put the story boards on my F last year and adjusted the rudder. What I got back was a 146 knot airplane. Flew it back to them and Dave adjusted it again to get it back to the old TAS.

I think why these planes are always a bit inconsistent is that it doesn’t take much mis-rigging to really make these plane slow.

In the picture I posted above and below, you can still see the rudder does still go out a little when I am at higher air speeds. That is why old MooneyMiser Phil used to sell the Aerotrim.




Sent from my iPad using Tapatalk Pro

[Marauder]

Norm, Chris.  Norm. 
Don't worry. When the time comes we'll remind you when to take your medicine. 
Agreed completely, FWIW. 
Jim

Thanks Paul. I’ll take my pill now.

Funny thing is I wrote Phil while I was thinking Norm. What pill do I need to take now?


Sent from my iPad using Tapatalk Pro

[jaylw314]

10 minutes ago, Marauder said:

In the picture I posted above and below, you can still see the rudder does still go out a little when I am at higher air speeds. That is why old MooneyMiser Phil used to sell the Aerotrim.

Sent from my iPad using Tapatalk Pro

If you think about it, though, the rudder trim is only precisely correct at one particular airspeed.  If you're faster or slower, it's going to be off in one direction or another.

Trying to calculate TAS is always going to be a little suspect.  Aside from the whole calibrated airspeed issue, there are other environmental variables.  I fly one of the slower J's out there, but I was feeling pretty good  last weekend when I calculated a KTAS of 155.  Until I realized I was flying near the Cascades and was probably in a mild mountain wave updraft.  When I came out of it and my KTAS dropped to 135, then I was feeling not-so-good... 

I think a round-trip GPS groundspeed is probably the better way of recording performance, e.g. fly a triangle or square round trip and average the speed from each leg.

[Marauder]

If you think about it, though, the rudder trim is only precisely correct at one particular airspeed.  If you're faster or slower, it's going to be off in one direction or another.
Trying to calculate TAS is always going to be a little suspect.  Aside from the whole calibrated airspeed issue, there are other environmental variables.  I fly one of the slower J's out there, but I was feeling pretty good  last weekend when I calculated a KTAS of 155.  Until I realized I was flying near the Cascades and was probably in a mild mountain wave updraft.  When I came out of it and my KTAS dropped to 135, then I was feeling not-so-good... 
I think a round-trip GPS groundspeed is probably the better way of recording performance, e.g. fly a triangle or square round trip and average the speed from each leg.

Not to mention fuel & other loading (fat arse like me or one those 5’4” Mooney drivers), age of the engine, etc.


Sent from my iPad using Tapatalk Pro

[MIm20c]

46 minutes ago, Marauder said:

The Aspen’s calculator is accurate as a calculator. It has a dependence on the information being fed in from the GPS and its own airspeed. What the true CAS is for these electronic gizmos will always be a question. Since I have another electronic gizmo (ESI-500) showing airspeed, I have plugged everything into the GTN and verified I am getting the same numbers as the Aspen.

 

I’m curious if members like @JohnB are getting similar TAS between the Aspen and TXI sitting side by side?

[Guitarmaster]

Instrument error will always exist.  Even the best calibrated airspeed will be off with varying conditions.

When I set forth to determine any speed gain with David's cowling, I used the four course speed test.  This mitigates the effect of instrument error as GPS is pretty accurate regardless of outside conditions.  

Prior to the cowling mod, I would see 147 KTAS on a cool day.  This was with LASAR cowl closure (which did nothing for speed).  After the mod, with similar conditions, I got 153 KTAS.  The summertime has me at 147 whereas I was at 143 before.  

I am comfortable saying there was a 4-6kt gain over a STOCK cowling.  

These tests were done at 100ROP which yielded about 11-12GPH.  The EDM showed 70% power.
 

[Hank]

37 minutes ago, jaylw314 said:

If you think about it, though, the rudder trim is only precisely correct at one particular airspeed.  If you're faster or slower, it's going to be off in one direction or another.

Trying to calculate TAS is always going to be a little suspect.  Aside from the whole calibrated airspeed issue, there are other environmental variables.  I fly one of the slower J's out there, but I was feeling pretty good  last weekend when I calculated a KTAS of 155.  Until I realized I was flying near the Cascades and was probably in a mild mountain wave updraft.  When I came out of it and my KTAS dropped to 135, then I was feeling not-so-good... 

I think a round-trip GPS groundspeed is probably the better way of recording performance, e.g. fly a triangle or square round trip and average the speed from each leg.

Don't feel too bad about 135 knots in your J. Over here, flying over hills from KGSP towards KTYS [only half the height of the Cascades], the groundspeed of my C dropped to 68 knots or 78 mph . . . At 10,000 msl, indicating 142 mph [quick:  142 + (2% x 10) = 142 + 20% = 170 mph or 148 knots ].