231: is it really a lower tier version?

[Hank]

"Is the 231 a lower tier version?"

No, they are nice machines. My C, on the other hand, could credibly be described as "lower tier," all 180 hp of her. I lucked into a good one  , but still, she ain't no K!

[Yooper Rocketman]

21 hours ago, Tx_Aggie said:

I don't know too much about the rocket conversion, what has 16 years convinced or taught you about it?! I'm interested to hear your thoughts. How does the bigger engine increase the useful load on the same sized airframe?? What fuel rates do you see at cruise/what altitudes do you prefer?

 

thanks!

The gross weight increase for the STC approved conversion is 300 lbs, goes from 2900 to 3200.  You lose 208 lbs of the gain to the conversion, but a net useful load increase of almost 100 lbs.  I rarely fly below 11k-12k, as with the turbo you will not gain much unless getting higher.  I file 190 knots at 12k, 200 at 18K and 210 at 23K.  That's at a lower power setting than Rocket Engineering shows for cruise, loss from my TKS deice system, and a 250 hour over TBO engine (surely lost some power from new).  My cruise power is 2300 RPM, 30" manifold, and 19 gallons an hour ROP.  A newer engine, no deice, and higher power settings will clearly net you faster cruise speeds.  Here is a link to the Rocket Engineering website for more info; http://www.rocketengineering.com/content/mooney-305-rocket

As far as what I like; minimum 1K minute climb to 24K, good cruise speed, relatively trouble free engine, proven in the twin Cessna's for years, and it's working a lot less in the Mooney airframe than in the large twins it's customarily found in.  The 1600 hour TBO is easily reached and, from my research, usually exceeded by up to 500 hours.  If you want pure performance, the Rocket is hard to beat.  If you're looking for a blend of performance and efficiency, I would still call the 252 the plane in the earlier airframes the best one.  I just couldn't find one when I was buying that met the bang for the buck like the Rocket (I'm talking purchase price, in 2001).

Tom

[Tx_Aggie]

53 minutes ago, Yooper Rocketman said:

The gross weight increase for the STC approved conversion is 300 lbs, goes from 2900 to 3200.  You lose 208 lbs of the gain to the conversion, but a net useful load increase of almost 100 lbs.  I rarely fly below 11k-12k, as with the turbo you will not gain much unless getting higher.  I file 190 knots at 12k, 200 at 18K and 210 at 23K.  That's at a lower power setting than Rocket Engineering shows for cruise, loss from my TKS deice system, and a 250 hour over TBO engine (surely lost some power from new).  My cruise power is 2300 RPM, 30" manifold, and 19 gallons an hour ROP.  A newer engine, no deice, and higher power settings will clearly net you faster cruise speeds.  Here is a link to the Rocket Engineering website for more info; http://www.rocketengineering.com/content/mooney-305-rocket

As far as what I like; minimum 1K minute climb to 24K, good cruise speed, relatively trouble free engine, proven in the twin Cessna's for years, and it's working a lot less in the Mooney airframe than in the large twins it's customarily found in.  The 1600 hour TBO is easily reached and, from my research, usually exceeded by up to 500 hours.  If you want pure performance, the Rocket is hard to beat.  If you're looking for a blend of performance and efficiency, I would still call the 252 the plane in the earlier airframes the best one.  I just couldn't find one when I was buying that met the bang for the buck like the Rocket (I'm talking purchase price, in 2001).

Tom

Great info Tom - I really appreciate it, all great points. Is the reachable 1600 hr TBO possible without a top overhaul? Do the cooling issues of the 231 cowling affect the Rocket design more or less as the cowling in the 252? Those are performance numbers that I really like. I understand it most likely comes at a certain cost, but then again if it's costs we're concerned about, should we really be flying? After looking through the listings, it's interesting to me that out of the available Rocket STC Mooney's, their costs are less than most 252's by atleast $10-15k. Thanks for the input. Now if you only lived in Texas, I might be able to find an excuse to check out your plane!

Thanks again, Matt

 

[aviatoreb]

3 hours ago, Yooper Rocketman said:

The gross weight increase for the STC approved conversion is 300 lbs, goes from 2900 to 3200.  You lose 208 lbs of the gain to the conversion, but a net useful load increase of almost 100 lbs.  I rarely fly below 11k-12k, as with the turbo you will not gain much unless getting higher.  I file 190 knots at 12k, 200 at 18K and 210 at 23K.  That's at a lower power setting than Rocket Engineering shows for cruise, loss from my TKS deice system, and a 250 hour over TBO engine (surely lost some power from new).  My cruise power is 2300 RPM, 30" manifold, and 19 gallons an hour ROP.  A newer engine, no deice, and higher power settings will clearly net you faster cruise speeds.  Here is a link to the Rocket Engineering website for more info; http://www.rocketengineering.com/content/mooney-305-rocket

As far as what I like; minimum 1K minute climb to 24K, good cruise speed, relatively trouble free engine, proven in the twin Cessna's for years, and it's working a lot less in the Mooney airframe than in the large twins it's customarily found in.  The 1600 hour TBO is easily reached and, from my research, usually exceeded by up to 500 hours.  If you want pure performance, the Rocket is hard to beat.  If you're looking for a blend of performance and efficiency, I would still call the 252 the plane in the earlier airframes the best one.  I just couldn't find one when I was buying that met the bang for the buck like the Rocket (I'm talking purchase price, in 2001).

Tom

That is really interesting to me Tom.  Your numbers are VERY close to mine - also a tks rocket.  And I have VGs, but a slightly younger engine (1350hrs).  I was wondering why I wasn't closer to book numbers.  But as you said....  Also I believe book numbers are on a 252 airframe, with smooth belly, hidden belly antenna, and the 3 piece gear doors that I do not have, that are worth a bit.  Mostly I think the hit is the tks though.  Still even slower than book, it is very fast.  I think I am climbing better than you cite though, by a good bit.

[Yooper Rocketman]

My climb is fixed (by habit) by feet per minute, not airspeed (cruise climb).  I have seen close to 2K a minute when it's cold and my initial climb is by airspeed.

Matt,

I have had one jug off for a burnt valve in 1850 hours.  My IA says this engine rarely gets that kind of life, and especially cylinder life, in the twins.  He thinks it's because of the very consistent operation I use in flying the airplane.  As far as cooling, I ALWAYS climb at full power, full RPM (38" and 2650 RPM).  Shortly after purchase, on a pretty hot day, I started getting above 400 degrees on the cylinders on climb, but was using the "cruise climb" power setting (35" and 2500 RPM).  Temps went down as soon as I resumed full power and RPM climb. I had issues only one time since, in hot weather up about 20K, needing to slow the climb a bit to keep cylinder temps under 400.

Tom

[KSMooniac]

Only the 252 is eligible for the GW increase that came with the Encore.  It is 230 lbs...quite substantial and not very costly to accomplish through Mooney.  The 231 is not eligible.

The Rocket (and Missile) gross increases were done as part of their STC's, and not available otherwise.  These conversions are still supported, and quite a value in today's market as many folks shy away from mods.  

There is a nice continuum of turbo Mooneys available depending on your budget and wishes.  You can get an un-upgraded early 231 for $70k or less, or a late-model Encore for $200k +/-, and just about everything in between.  

I know of a nice Rocket that might be available in KS if you're interested.  PM me for details...I'd love to help a fellow Aggie!  

[aviatoreb]

58 minutes ago, Yooper Rocketman said:

My climb is fixed (by habit) by feet per minute, not airspeed (cruise climb).  I have seen close to 2K a minute when it's cold and my initial climb is by airspeed.

Matt,

I have had one jug off for a burnt valve in 1850 hours.  My IA says this engine rarely gets that kind of life, and especially cylinder life, in the twins.  He thinks it's because of the very consistent operation I use in flying the airplane.  As far as cooling, I ALWAYS climb at full power, full RPM (38" and 2650 RPM).  Shortly after purchase, on a pretty hot day, I started getting above 400 degrees on the cylinders on climb, but was using the "cruise climb" power setting (35" and 2500 RPM).  Temps went down as soon as I resumed full power and RPM climb. I had issues only one time since, in hot weather up about 20K, needing to slow the climb a bit to keep cylinder temps under 400.

Tom

Ah - so maybe we are very close after all.  I have climbed to 17000 in 12:xx min once on a cold day.

I think this installation of the tsio520nb is especially well cooled and implemented, AND de-rated compared to many twin applications which often go 325 or 335hp which must also be why it has better than usual longevity.

[Yooper Rocketman]

On 5/20/2016 at 6:24 PM, Yooper Rocketman said:

I have had one jug off for a burnt valve in 1850 hours.  

After thinking about this, I remember it WASN'T a burnt valve, it was a STUCK valve, from sitting too long between flights.  I had times, busy with business, log home and Lancair building, where I would go several months without flying.  I was admonished by my IA, as he was changing the jug, to fly at LEAST once a month, whether I needed to or not, (and have ever since).

Tom

[M20F]

On May 17, 2016 at 8:46 AM, jlunseth said:

Yes to Lance's comment, and the 231 at 10-12k is more like a 160 kt. aircraft, maybe 165, but not 180.  You have to put the whole crew on the oars, whip them up, and go up to at least 22,000 before you will see 180 at cruise power, and not likely then.  More like mid-170's.  GS in that range with a good tailwind, that I can see, but not TAS.

My F get's between 160-170 at 75% at FL190 and 135-145 down low (i.e. it's a slow F).  I would expect a K to be 20kts faster than me. 

[Zwaustin]

I love my 231, it has been very reliable. It, imho is not a lower tier machine. Have flown it roughly 160 hours in the last 10 months and is rock solid. I see about 160-170 True typically depending on how high I go. Run LoP at about 9 gallons per hour give or take. I have an intercooler and no merlyn. Highly recommend the 231 for the money. 

[Steve Dietrich]

On 5/17/2016 at 8:50 AM, kortopates said:

Its possible in that Continental allows it and provides guidance on how to alter that engine data tag in the field (unlike Lycoming whom does not allow it), but its not practical as it would require altering the engine so that it entirely conformed to the MB specification which would include at least the exhaust, induction, intercooler, controller, wastegate, and starter adapter and probably much more. It would likely take salvage parts to make it even possible from a dollars standpoint and then you have the 262 STC for the airframe which I don't think anyone is providing anymore. Much easier to upgrade by trading up.

No ,  as far as I know there is no STC for a baro controlled wastegate for the LB motor.     As Paul notes you would be far better off buying a converted aircraft as the cost of the conversion is probably $60K or more today.  It is not just the engine and turbo but also a different motor mount, cowl, cowl flap, .  The cowling plays a major role in both airspeed and cooling. The single cowl flap has less drag and is infinitely adjustable   The converted 231s used to have a significant disadvantage due to the single alternator 12 v system.  However, newer avionics and lights have a much lower power draw. Replacement of the T&B with a second solid state AI with backup power adds a lot of reliability.