Mooney Rocket pro's and cons

[aviatoreb]

There are a number of lovely rockets on the market now for seemingly excellent prices.  What is the catch?!  

Can any Mooney Rocket owner please report if you may since I am inching closer to leaping - 

-Are they harder to fly than a 231?

-Are they harder to get insurance for than a 231?  Or much more costly maybe?

-How is the safety record for rockets vs 231s?

-Here is the biggy - I know they burn more full when you push them and reports are that they scream - and that is awesome for when I want to go somewhere and time counts.  I hear 20+gph is the norm.  That is half my mission space.  The other half is just training and maybe heading for a $100 hamburger.  How slow can you go?  WHat is the lowest reasonable gph?  I read on Mooneyland the review a closing comment that said that if you go 231 speeds then you burn 231 fuel.  Does that mean you can slow down enough to get 13 or 14gph?

-Does anyone know what is the overhaul cost of that particular big continental?

 

Thanks!

Erik

[donshapansky]

I run my Rocket 2 ways, into a headwind I run ROP (TIT 120 - 150 F below 1650 F) at 2450 and 30 inches for approx 20-21 gph with all head temps at 380 or less. With a tailwind I will run LOP with all cyls at or greater than 50 F LOP for 14 gph, all cyls are 360 F or less and the MP is 29 in. @ 2400 rpm. (62% power) At 8 - 9 K the ROP TAS is 195 kts and LOP is 183 kts +/-

It takes a well maintained ignition system with GAMI's to do this but the engine will run smoothly LOP and more importantly the TIT is well under the 1650 F max ( a couple of days ago at 9500' at 18C LOP, the TIT was 1530 F).

I just pulled all cylinders on my Rocket at 750 hrs SNEW (ECI Cerminil) all bores were straight with no wear, we freshened everything with new valves, springs, wrings etc. The valves and seats were in good shape with no discernable guide wear, we had 2 stuck rings and a broken inner valve spring was found. The airplane was in Venice Florida for about a year and 50 hrs SMOH, the humidity did its thing and caused the ring problem. Oil temp is another important item to control, I have to run a baffle in TX between Nov and Mar to get the temp anywhere close to 180 F. The Rocket cooler is very effective in a TX summer, but overly effective in winter. 

[KLRDMD]

Quote: donshapansky

I run my Rocket 2 ways, into a headwind I run ROP (TIT 120 - 150 F below 1650 F) at 2450 and 30 inches for approx 20-21 gph with all head temps at 380 or less. With a tailwind I will run LOP with all cyls at or greater than 50 F LOP for 14 gph, all cyls are 360 F or less and the MP is 29 in. @ 2400 rpm. (62% power) At 8 - 9 K the ROP TAS is 195 kts and LOP is 183 kts +/-. 

[donshapansky]

It doesn't add back the speed but it does run rough. I believe that there is a difference between a turbo normalized engine's behavior LOP and a turbo supercharged engine. The compression ratio difference makes the turbo work harder in the case of the lower compression ratio. This has been confirmed by Tim at GAMI. 

[KLRDMD]

Quote: donshapansky

It doesn't add back the speed but it does run rough. I believe that there is a difference between a turbo normalized engine's behavior LOP and a turbo supercharged engine. The compression ratio difference makes the turbo work harder in the case of the lower compression ratio. This has been confirmed by Tim at GAMI. 

[donshapansky]

I could tolerate the roughness if the speed came back but it didn't even with John Paul from GAMI operating the levers, the fuel spreads didn't change and if I recall the TIT became the limiting factor in richening the mixture to recover the power loss.

[KLRDMD]

Quote: donshapansky

I could tolerate the roughness if the speed came back but it didn't even with John Paul from GAMI operating the levers, the fuel spreads didn't change and if I recall the TIT became the limiting factor in richening the mixture to recover the power loss.

[donshapansky]

It seems that it is not uncommon in several engine combos such as this one but certainly not unique to this configuration. Many Lycs have this limitation as well according to GAMI.

[aviatoreb]

Quote: donshapansky

>I run my Rocket 2 ways, into a headwind I run ROP (TIT 120 - 150 F below 1650 F) at 2450 and 30 inches for approx 20-21 gph with all head temps at 380 or less. With a tailwind I will run LOP with all cyls at or greater than 50 F LOP for 14 gph, all cyls are 360 F or less and the MP is 29 in. @ 2400 rpm. (62% power) At 8 - 9 K the ROP TAS is 195 kts and LOP is 183 kts +/->It takes a well maintained ignition system with GAMI's to do this but the engine will run smoothly LOP and more importantly the TIT is well under the 1650 F max ( a couple of days ago at 9500' at 18C LOP, the TIT was 1530 F).

 

Thanks Don, that was very useful.

Do you ever use your airplane for local missions?  For a hundred dollar hamburger?  Can you do that with this plane?  Is there a 45% to 55% setting for loping around and if so what kind of gph and speed does that make?

How about landing.  Is this plane much different/harder from landing a stock 231?

[brettinlj]

[bd32322]

I'm resurrecting this topic because I have the same two questions above. I am considering getting into a partnership in a Rocket but am curious about suitability for occasional local flights. Is there a cruise power setting under 55%?

Yes you can reduce power to whatever, but you wont get the miles per gallon of a J. The MPG only matters ofcourse, if you have to go somewhere local for the hamburger.

If you just do some air work and return to your starting point, you should be able to get the fuel flow down to a level where the fuel bill wont gouge a huge hole in your pockets. However, you would also like to get some decent oil and CHT temps while you are doing this in order to get rid of moisture from oil for example. So that would set a lower bound for your MPG and fuel flow.

I am not biased against rockets, because I am looking to buy one myself.

[chrisk]

I was considering a Rocket for a period of time.  I found it useful to look at an example on the controller.  http://www.controller.com/listingsdetail/aircraft-for-sale/MOONEY-M20K-231/1981-MOONEY-M20K-231/1255725.htm This one has the log books posted and you can get an idea of what maintenance is being performed beyond any other plane.