gross weight question

[tnathan]

I have been considering a mooney 252, rocket, etc.  Due to the economy,  the cost of these seem to have come down enough that I may try to buy one over the next year or so.  My goal is to be able to take myself, wife and bags 600NM in around 3 hours, with a fuel burn that won't bankrupt me and I don't want to manage fuel which has lead me to the mooneys noted above.  The speed and range seems to be close, but  my biggest concern is gross weight.  I saw the specs for the rocket coversion which seemed perfect but when I actually look into particular aircraft, much like myself they have put on a lot of weight over the years.  I was hoping for something with around 500-600lbs payload.  However, the few rockets I ran across after 100gal tanks and whatever else has been added they end up with 300-400 payload.  I saw the TLS has an STC to increase gross.  Does anything like that exist for the rocket?  It seems like as the engines get bigger and have a higher gross the empty weight goes up and the fuel burn goes up which means people add bigger tanks which further raises the enpty weight.  End result is that the payload often decreases.  Any thoughts or comments out there from those of you that know these birds better than me?  Thanks.

[carqwik]

The Bravo will do that trip in 3.5 hours at 20 gph.  You'd be close or at gross weight on t/o.  I never heard of an STC for a weight increase on that model.

[Parker_Woodruff]

Mooney M20K 252 or Encore (from the 1990s) will fit that well.  The Encore had an increase in weight by more than 200 lbs.

 

Early Ovations would do well too if you choose not to fly at full fuel capacity.  Some had useful loads in the 1050lb range.

[blacknchrome]

"However, the few rockets I ran across after 100gal tanks and whatever else has been added they end up with 300-400 payload. "

 

Just remember, just because it has 100 gallon tanks, doesn't mean they need to be filled.   For your 600nm trip, you need far less fuel than full tanks, which will allow you to carry more 'stuff'.   

I can carry 118 gallons in the Bravo, but unless I am by myself, full fuel doesn't work on paper. 

It's just another aspect to manage of our very capable, beautiful airplanes.

[carusoam]

Roughly speaking.....

Ovation 1: Assume...

16gph in level flight at 170 knots (11,500 feet)

89 gallons usable. 5 hours of flight if needed...

600 nm trip = 3.5hrs  (60 gallons) 360 lbs of fuel

1050 useful (from Parker, noted above). 

Leaving 690# usable for people and stuff.

Consider Ovations M20R and Eagles M20S may give similar results.

For two people, there is alot of extra capacity for additional fuel, or bringing alot of stuff......

Of course, this is rough, quick, back of the hand calculation intended to help illustrate a possible solution.  Please check the math yourself.  Don't forget to add your reserves and actual fuel flow for climb, etc....

I think rockets and TLS/Bravos would do this run a bit quicker at higher altitudes, bring your oxygen...

Best regards,

-a-

[tnathan]

Quote: blacknchrome

Maybe I will get comfortable with it, but I prefer to be able to touch the gas before I go.  Managing fuel is just one more thing to worry about.   

"However, the few rockets I ran across after 100gal tanks and whatever else has been added they end up with 300-400 payload. "

 

Just remember, just because it has 100 gallon tanks, doesn't mean they need to be filled.   For your 600nm trip, you need far less fuel than full tanks, which will allow you to carry more 'stuff'.   

I can carry 118 gallons in the Bravo, but unless I am by myself, full fuel doesn't work on paper. 

It's just another aspect to manage of our very capable, beautiful airplanes.

[tnathan]

Sounds like it isn't as bad as I thought.  It just seemed like the generic weight quotes I see online seemed to be significantly different than real world numbers I found when I drilled down on particular planes that actually happened to be for sale.  Maybe it is inexperience but I really don't want to manage fuel.  Did I put in 60 or 70gals?  

The newer mooneys are nice but out of my price range.

THe rocket interested me because it seems to be cheap.  On paper, it purportedly added 200lbs of weight with a 300lbs increase in gross for a net increase of 100.  I was told that the rocket conversion has a reliable engine and turbo which is better than the stock 231.  And, although the top end fuel burn is comparatively high, you can always pull it back to 231 performance and get comparable fuel burns.   It seemed like the best of all worlds. 

 

However, when I actually found one, the empty weight had mysteriously gone up by 300lbs and they added 100gal tanks so the net was a loss in useful load.  I was curious if there is anyway to salvage a plane that has gotten fat.  The gross on the newer mooneys seems to have gotten larger.  I didn't know if there was much that could be done to increase gross on an older 252, rocket.  Based on the comments it sounds like there isn't.  I have heard with other planes you can up gross with things like beefing up the landing gear, vortext generators.  Thanks for your help.

 

[KSMooniac]

There is no additional gross weight increase available for the Rocket or Missile conversions.  There is a gross weight increase available for the 252 if it is converted to an Encore configuration, but it will likely bust the budget unless you got the 252 for really cheap and in need of an overhaul.

Managing fuel load vs. payload is an important aspect of operating any high performance plane.  Simply "topping it off" for every flight is frankly quite silly, and reduces performance, especially if filling extended fuel tanks.  These days a modern fuel totalizer system is relatively inexpensive and offers tremendous safety benefits starting with managing partial-fuel situations when you need to carry more in the cabin on a trip.

My J has fuel tabs at 25 gallons, and 32 gallons max per side.  I opted to add the wing mechanical fuel gages when I had my tanks re-sealed so that I can always tell what I have.  I also have a JPI EDM-700 with the fuel flow option, and I have used that totalizer quite a few times to balance fuel and payload.  It is quite nice to *know* I have 42 gallons to start a 450 NM trip and watch it burn down and verify my reserves.  If I didn't have that, I would likely have to fill to 50 gallons and leave something behind, or else fabricate a very accurate dipstick and fiddle with the fueling on the ground to get to 42 gallons.

My advice is to get over the irrational fear of managing fuel and look closer at how you can balance the useful load of any candidate airplane with your planned mission.  You'll probably find that a Rocket or 252 will be able to do it just fine!

[Jeff_S]

Quote: carusoam

Roughly speaking.....

Ovation 1: Assume...

16gph in level flight at 170 knots (11,500 feet)

89 gallons usable. 5 hours of flight if needed...

600 nm trip = 3.5hrs  (60 gallons) 360 lbs of fuel

1050 useful (from Parker, noted above). 

Leaving 690# usable for people and stuff.

Consider Ovations M20R and Eagles M20S may give similar results.

For two people, there is alot of extra capacity for additional fuel, or bringing alot of stuff......

Of course, this is rough, quick, back of the hand calculation intended to help illustrate a possible solution.  Please check the math yourself.  Don't forget to add your reserves and actual fuel flow for climb, etc....

I think rockets and TLS/Bravos would do this run a bit quicker at higher altitudes, bring your oxygen...

Best regards,

-a-

[carusoam]

The goal was, two people, 600nm in 3.0 hours.... neither the J or the R really meets the time requirement, the R is slightly closer.....

On a less limited budget, I would get the Acclaim to get there fast, an M20J to get there most efficiently, an M20R to bring "efficiency minded" friends along comfortably, and an M18 for days you just want to go it alone.  This would be my version of the Al Mooney Collection.

As far as partial fuel loads.  Modern systems are difficult to mess up.

Two tanks with fuel quantity sensors in them.  Two visual gauges on the wing top.  Fuel totalizer while flying, integration into GPS - fuel required to waypoint, with alarms and lights.

You still have the option to look into the tank (which I do on every flight).

Any faster, you would need to consider a turbine........TBM anyone?

-a-

[RJBrown]

The gross weight of a Rocket is, or can be changed to, 3200#. My old Rocket had a usefull over 1100#. Full fuel was 101 useable, or 606#. This left 515# of legal payload. The TLS has a gross weight of 3368. Both share the same flying surfaces. The TLS was allowed the higher gross weight, not because it could lift more but because it could land heavier. The landing gear was beefed up on the TLS so it could keep a similar useful load at the higher gross weight. The 305HP Rocket will always be able to out climb and out run a 270HP TLS at any weight.  A 3130# gross weight Encore may have a greater usefull than any other Mooney if the 1800 empty weight is to be believed. I for one can't imagine an Encore under 1900# empty. Any real world Encore drivers out there?

Was the Rocket you looked at an early one? The ones finished before the 3200# gross was approved may have a lower useful.

[jasonwojo]

I have two Rockets, a '79 K with 310 hp and 104 gallons useable, and a '91 TLS/Bravo with 350 hp and 118 gallons useable.  Both are awesome aircraft that will meet your needs, but they do require some common sense planning when it comes to fuel/loading.  The '79 has a 3,200 lb max weight, and the '91 has a 3,368 lb max takeoff weight (3,200 lb max landing weight).  Both planes have electronic fuel flow guages (combination of JPI, EI, and Hoskins) that talk to the GPS/MFD, and the '91 has mechanical guages in the wing.  There are plenty of tools available to us to manage our fuel without having to always top off.  As far as the Rockets, they are a great product that are backed by a caring company (they love Mooneys and they loved these conversions).  Let me know if you have any questions.  If you are in the area, let me know and I will show you some speed!