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231 vs 201: speed at low altitude


jrwilson

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So I always hear the 201 is faster than a 231 at lower altitudes with the usual consensus that a 201 will outrun a 231 below either 8,000 or 10,000, depending on whose telling the tale...

i have a bit of time in a few 201s and have owned a 231 for about 4 years.  

The 201s I’ve flown do between 155 and 160 kt tas at around 8k, slowing a bit the lower and higher you go.  

My 231 does about 166kt at 8k, slowing a bit the lower I go and of course speed as I climb.

around 5,500 I do just under 160kt.  

what do others see with their 201s and 231s?  What is your speed at 5,500, pwr setting and fuel flow?

here is 5,500/28”/2500/12.7 fuel

38D09729-CD48-4EE2-8DC1-87E4DC54012C.thumb.jpeg.400c9cc06e8d8c30049e342373d0f5e5.jpeg

 

23AB8B58-BC11-49F4-89FD-B45B42A6AD1A.thumb.jpeg.935121acd242eaa829e6304268591aeb.jpeg

 

and 3500/25.3”/2500/10.3fuel

DC619B6B-A02E-4EE7-9484-B5843E4B2CA3.thumb.jpeg.95b4e0e04a2951d3c14a08279f9714e2.jpeg

 

0704DA75-4F05-434F-A95E-EA44A7CF39DE.thumb.jpeg.e1a730fe9613d53a38c5a24a19072bda.jpeg

 

sorry abiut the sideways pictures...  @marauder can You fix that?

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40 minutes ago, jrwilson said:

So I always hear the 201 is faster than a 231 at lower altitudes with the usual consensus that a 201 will outrun a 231 below either 8,000 or 10,000, depending on whose telling the tale...

i have a bit of time in a few 201s and have owned a 231 for about 4 years.  

The 201s I’ve flown do between 155 and 160 kt tas at around 8k, slowing a bit the lower and higher you go.  

My 231 does about 166kt at 8k, slowing a bit the lower I go and of course speed as I climb.

around 5,500 I do just under 160kt.  

what do others see with their 201s and 231s?  What is your speed at 5,500, pwr setting and fuel flow?

here is 5,500/28”/2500/12.7 fuel

38D09729-CD48-4EE2-8DC1-87E4DC54012C.thumb.jpeg.400c9cc06e8d8c30049e342373d0f5e5.jpeg

 

23AB8B58-BC11-49F4-89FD-B45B42A6AD1A.thumb.jpeg.935121acd242eaa829e6304268591aeb.jpeg

 

and 3500/25.3”/2500/10.3fuel

DC619B6B-A02E-4EE7-9484-B5843E4B2CA3.thumb.jpeg.95b4e0e04a2951d3c14a08279f9714e2.jpeg

 

0704DA75-4F05-434F-A95E-EA44A7CF39DE.thumb.jpeg.e1a730fe9613d53a38c5a24a19072bda.jpeg

 

sorry abiut the sideways pictures...  @marauder can You fix that?

I think the crossover is at ~6000.  As I data point, my box stock F model will due a touch better than 150Kcas 3500'.  I wish I were closer to Longview, it'd be fun to participate in the speed trials and see how the different models do.

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Race! Race! Race!

Met a K pilot who told me his bird “consistently” beat book. Surprised, but OK...when we flew form, his ASI was “consistently” reading higher than any other plan with whom he flew. As suspected (and verified by multiple GPSs) his ASI was in need of adjustment.

There is no definitive altitude at which one prevails over the other, nor can there be with so many variables: temperature, density altitude, gross weights, speed/engine mods, etc.

My own experience is Js, Fs and Es will out-accelerate Ks and retain a “smash” advantage to at least the altitudes suggested here (from 6-8,000).

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Race! Race! Race!

Met a K pilot who told me his bird “consistently” beat book. Surprised, but OK...when we flew form, his ASI was “consistently” reading higher than any other PLANE with whom he flew. As suspected (and verified by multiple GPSs) his ASI was in need of adjustment.

There is no definitive altitude at which one prevails over the other, nor can there be with so many variables: temperature, density altitude, gross weights, speed/engine mods, etc.

My own experience is Js, Fs and Es will out-accelerate Ks and retain a “smash” advantage to at least the altitudes suggested here (from 6-8,000).




Fixed it.
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22 minutes ago, N9201A said:

Race! Race! Race!

Met a K pilot who told me his bird “consistently” beat book. Surprised, but OK...when we flew form, his ASI was “consistently” reading higher than any other plan with whom he flew. As suspected (and verified by multiple GPSs) his ASI was in need of adjustment.

There is no definitive altitude at which one prevails over the other, nor can there be with so many variables: temperature, density altitude, gross weights, speed/engine mods, etc.

My own experience is Js, Fs and Es will out-accelerate Ks and retain a “smash” advantage to at least the altitudes suggested here (from 6-8,000).
 

My experience is that I could out climb a neighbor’s Bravo through at least the first 3,000 feet. He flew with me on numerous occasions and would often point at my VSI and say, “I wouldn’t believe it if the gps wasn’t saying the same thing”.

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Similar to J vs K...

Bring the Screamin’ Eagle for a NA baseline...

Bring the 310hp Acclaim for the TN baseline...

The 2kfpm climbs are a blast...

The FF keeps a damper on all that fun...

 

The carusoam dream plane will have twin turbos and built in O2.

If the Dream gets bigger... turbine... and a built in fuel card.   :)

 

PP thoughts, gone awry...

Best regards,

-a-

 

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5 minutes ago, carusoam said:

Similar to J vs K...

Bring the Screamin’ Eagle for a NA baseline...

Bring the 310hp Acclaim for the TN baseline...

The 2kfpm climbs are a blast...

The FF keeps a damper on all that fun...

 

The carusoam dream plane will have twin turbos and built in O2.

If the Dream gets bigger... turbine... and a built in fuel card.   :)

 

PP thoughts, gone awry...

Best regards,

-a-

 

I used to dream about a 450hp turbine bolted on the front of my Mooney.  (Sorry lil ol rocket TSIO520NB - if a Rolls Royce shows up, then asta la vista avgas),

but now....

I dream of a Siemens electric motor generating the equivalent of 400hp bolted to the front of my mooney, with the battery technology to match - so I will need to wait 20 years.

But when that Siemens is ready for my lil ol Mooney, then the Rolls Royce turbine is going to the junk pile.  Asta la vista jet A.

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When you can climb at 2000fpm... there isn’t much incentive to hang out so low.... when speed and efficiency are only a few k’ away... measured in minutes....

 

There must be a Rocket Engineering fly-in somewhere...

Missiles, Rockets, Screamin’ Eagles, Standing Os, and Critical Acclaims...

Jerry Jet-Prop will be invited... P46T.  An RE project...

Ex Rocket owner, Turbine Tom will be on the extended guest list...

And the other Brand B guys...

https://rocketengineering.com/wp-content/uploads/2017/10/TurbineAir_Article_5-13-03.pdf

 

500shp. North American (Canada) made. P&W PT6A

Perfect for a Mooney... 250+ KTs... 30gph JetA

 

Great for that extended wait... until the battery technology catches up with the Siemens drives...

Unfortunately, RE knows their math really well.... they count TAM in hull numbers... total addressable market...

So...  the turbine is going to need to fit... at least K and other Six cylinder Mooneys, based on space available under the cowl...

The J has a high probability of working out... As the Missile adopted a K cowling to cover the extra cylinders...

The FF has less of a damper when it is not 100LL...

 

Send notes and letters of support to Darwin Conrad and Jeanie Sadler, Rocket Engineering... :)

 

unhinged PP thoughts only, not a mechanic...

Best regards,

-a-

 

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24 minutes ago, carusoam said:

When you can climb at 2000fpm... there isn’t much incentive to hang out so low.... when speed and efficiency are only a few k’ away... measured in minutes....

 

There must be a Rocket Engineering fly-in somewhere...

Missiles, Rockets, Screamin’ Eagles, Standing Os, and Critical Acclaims...

Jerry Jet-Prop will be invited... P46T.  An RE project...

Ex Rocket owner, Turbine Tom will be on the extended guest list...

And the other Brand B guys...

https://rocketengineering.com/wp-content/uploads/2017/10/TurbineAir_Article_5-13-03.pdf

 

500shp. North American (Canada) made. P&W PT6A

Perfect for a Mooney... 250+ KTs... 30gph JetA

 

Great for that extended wait... until the battery technology catches up with the Siemens drives...

Unfortunately, RE knows their math really well.... they count TAM in hull numbers... total addressable market...

So...  the turbine is going to need to fit... at least K and other Six cylinder Mooneys, based on space available under the cowl...

The J has a high probability of working out... As the Missile adopted a K cowling to cover the extra cylinders...

The FF has less of a damper when it is not 100LL...

 

Send notes and letters of support to Darwin Conrad and Jeanie Sadler, Rocket Engineering... :)

 

unhinged PP thoughts only, not a mechanic...

Best regards,

-a-

 

I'll be there!

...what about my Siemens electric rocket?

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I had a 64e that would do 162ktas at 10k...4 way gps runs. What i found odd was that I climbed t where I had 23"map, about 8500ft and did the 4 way. Got 162.75 ktas. Then I climbed to where I had 21"map, about 10,500, did the 4 way and got 162.75 ktas. All done at 2550rpm. Seems I should have been slower up high. I have a panel pic and gps pic of my e doing better than 160 ktas at 12K while showing a 200ft per min climb. Way faster than a $60,000 airplane has a right to be:) I'm really itching to restore another one:)My hottest cht was 305:)

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30 minutes ago, Pete M said:

I had a 64e that would do 162ktas at 10k...4 way gps runs. What i found odd was that I climbed t where I had 23"map, about 8500ft and did the 4 way. Got 162.75 ktas. Then I climbed to where I had 21"map, about 10,500, did the 4 way and got 162.75 ktas. All done at 2550rpm. Seems I should have been slower up high. I have a panel pic and gps pic of my e doing better than 160 ktas at 12K while showing a 200ft per min climb. Way faster than a $60,000 airplane has a right to be:) I'm really itching to restore another one:)My hottest cht was 305:)

What mods did your E have?

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On 5/18/2019 at 8:27 PM, aviatoreb said:

I dream of a Siemens electric motor generating the equivalent of 400hp bolted to the front of my mooney, with the battery technology to match - so I will need to wait 20 years.

The Army Research Laboratories just recently made a breakthrough which allows Lithium-based batteries to store twice as much energy in the same mass: https://www.army.mil/article/221700/army_discovery_opens_path_to_safer_batteries

The last time I ran the math, my -A1D delivers ~2.1 HP*hr per lb of fuel at 65% cruise (3.47 kWh/kg).

This discovery bring lithium batteries up to around 460 Wh/kg.  A good ESC/motor combination can easily hit 95% efficiency, so that puts battery power up to 1/8 what fuel power can currently deliver.  Three more doublings, and electrical power deliver will match ICE, lb for lb.

A bit of googling around suggests that a 180HP brushless motor could weigh 150-200 lbs - which is a solid 100-150 lbs less than my -A1D.  That would allow me to carry 50% more weight in batteries than i currently do in fuel, which means that only two doublings need to take place to get me to almost same endurance... (would be about 4 hours at 65%, current endurance is 5.25hrs@65%)

 

The Future is Coming.

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3 hours ago, ShuRugal said:

The Army Research Laboratories just recently made a breakthrough which allows Lithium-based batteries to store twice as much energy in the same mass: https://www.army.mil/article/221700/army_discovery_opens_path_to_safer_batteries

The last time I ran the math, my -A1D delivers ~2.1 HP*hr per lb of fuel at 65% cruise (3.47 kWh/kg).

This discovery bring lithium batteries up to around 460 Wh/kg.  A good ESC/motor combination can easily hit 95% efficiency, so that puts battery power up to 1/8 what fuel power can currently deliver.  Three more doublings, and electrical power deliver will match ICE, lb for lb.

A bit of googling around suggests that a 180HP brushless motor could weigh 150-200 lbs - which is a solid 100-150 lbs less than my -A1D.  That would allow me to carry 50% more weight in batteries than i currently do in fuel, which means that only two doublings need to take place to get me to almost same endurance... (would be about 4 hours at 65%, current endurance is 5.25hrs@65%)

 

The Future is Coming.

Very nice analysis.  General bravado confidence - I think we will get there before tooooo long.

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3 hours ago, ShuRugal said:

The Army Research Laboratories just recently made a breakthrough which allows Lithium-based batteries to store twice as much energy in the same mass: https://www.army.mil/article/221700/army_discovery_opens_path_to_safer_batteries

The last time I ran the math, my -A1D delivers ~2.1 HP*hr per lb of fuel at 65% cruise (3.47 kWh/kg).

This discovery bring lithium batteries up to around 460 Wh/kg.  A good ESC/motor combination can easily hit 95% efficiency, so that puts battery power up to 1/8 what fuel power can currently deliver.  Three more doublings, and electrical power deliver will match ICE, lb for lb.

A bit of googling around suggests that a 180HP brushless motor could weigh 150-200 lbs - which is a solid 100-150 lbs less than my -A1D.  That would allow me to carry 50% more weight in batteries than i currently do in fuel, which means that only two doublings need to take place to get me to almost same endurance... (would be about 4 hours at 65%, current endurance is 5.25hrs@65%)

 

The Future is Coming.

Check this out: https://www.harbourair.com/harbour-air-and-magnix-partner-to-build-worlds-first-all-electric-airline/

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I am one of the people that generally repeats this.  The place I've seen it stated most frequently is in Aviation Consumer, but the MSCs I've dealt with generally also seem to acknowledge the 200hp Lycoming Mooneys will be better performers down low.  My own experience transitioning through Mooneys (from 172s via 30 hours split between two different J's, followed by my 231) seems to bear this out, although there's kind of an asterisk.  My plane's fuel flow was never completely accurate, so I was always flying my 231 in an economy profile.  I never had the engine instrumentation to really open it up.  What I learned, flying it this way and flying a J model on the same 8.5-ish GPH pretty much backed up what I'd read.  On my 231 I manage maybe 135 knots on 8.5 GPH at 2500 MSL, and more like 160 knots up at 17,500.  The J models I flew differently.  Basically WOT all the time, rich down low where they went fast and leaner up over 7500 feet or so, where they managed ~150 knots at around 8500'.  This kind of just makes sense.  The planes, for all intents and purposes, make the same power and the K model is slightly draggier.  Same power, more drag, less speed.

To some extent it's kind of academic because you're probably not going to fly either plane long distances at 4500' at 70% power.  If you're in a 201, you're probably going to be flying it at 8500-10500 without oxygen, about optimal for plane and pilot.  If you're in a 231, you're going to be flying it in the mid teens or higher, on oxygen, also about optimal for plane and pilot.  And you'll be going faster on the same gas.

It's probably also worth pointing out that given the hand-built nature of the planes, accident history, quality of repairs, etc. that picking a J and K model at random from the actual, existing fleet, buzzing them up to 6500', and setting them each up to burn the same fuel, who knows which one will actually go faster.

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1 hour ago, FloridaMan said:

My 231 does way more than 166kts at 8500

Help me understand. The 231 has 210 max. HP and the same prop blades as the 200 HP 201. The airframes are basically the same. It would seem that up to about 8500 feet at 75% power, they should perform similarly. Above 8500', the normally aspirated 201 will lose power and slow down. The turbocharged 231 can maintain 75% power up to it's critical altitude and will pull ahead. This is just theory, not experience: It's been 30 years since I last flew a 231. Am I missing something?

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13 minutes ago, PT20J said:

Help me understand. The 231 has 210 max. HP and the same prop blades as the 200 HP 201. The airframes are basically the same. It would seem that up to about 8500 feet at 75% power, they should perform similarly. Above 8500', the normally aspirated 201 will lose power and slow down. The turbocharged 231 can maintain 75% power up to it's critical altitude and will pull ahead. This is just theory, not experience: It's been 30 years since I last flew a 231. Am I missing something?

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He’s being a smart ass! His 231 has a 305HP TSIO520 with a full feathering McCauley hanging out front.

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On 5/19/2019 at 11:31 AM, Pete M said:

none really...flap gap seals was all and I would have preferred not to have those.

Wow, that’s a fast E, what did you attribute the speed to?  That kind of speed is usually with J mods.  I can get about 152 ktas at about 7k, ROP,  WOT, ram air,  with just me...no mods and rather well rigged.

What didn’t you like about the flap seals?  Did it change low speed characteristics?

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Was 64 so was narrower at the cowl, New motor, eci cam, new lyc cylinders, new prop, timed 25btdc, ailerons rigged at 0, flaps up a bit maybe, new paint with a sanding primer. It was really smooth. New, light radios, slick mags, skytec starter so cg may have been more rear than stock. It was quite a bit slower when i bought it. Had the challenger air filter. Old wiring and atennas removed. If I was to do it again today I'd have lycon work the cylinders and bolt on that exaust from either power flow or the other guy thats been mentioned here. Im sure I could get more out of it.

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The most common trip in my 231 is 200nm so I generally stay below O2 altitudes. Here are some results from Monday:

6,500 FT +3C

75% Best Power 125 ROP (According to the Chart) - 163 KTAS 13.3 GPH

65% LOP - 156 KTAS 10 GPH

10,500 FT -5C

75% Best Power - 170 KTAS 13.3 GPH

65% LOP - 162 KTAS 10.1 GPH

And here's the best part about a turbo, if you want to go fast you can:

10,500 FT -5C

85% Best Power - 181 KTAS 15.5 GPH

My non-intercooled bird likes the cooler air temps, it isn't as fast on a hot day. All CHT's were below 360 that day.

 

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