Overgross

[AndyFromCB]

So, I get back to the airport (KAPA) sunday afternoon after spending the weekend at Grand Lake, CO. Go out to check my fuel, I'm loaded way past the tabs, run some numbers, calculated to be about about 200lb over gross. I go back to the desk at Tac Air and inform them of the situation. I guess they thought since the fuel is a dollar off on Sundays, I wanted full tanks. Anyways, I decided that taking off over gross from Denver is asking for trouble, so I rented a car and next morning their mechanic downloaded 30 gallons. They were really great about it including paying for my rental car Sunday night and taking off 30 gallons of the bill. Hats off to Tac Air for fixing the problem.

 

Well, as I am walking out Monday afternoon for the flight home, I see another Bravo just came in to land, 4 big guys and more luggage than I though was possible to fit in a Mooney. You know they were over gross on landing, who knows how much on take off. Then I see a J taxing to take off, same story, 4 big guys filling up the airplane. I guess some people have more balls than I do.

 

The amazing thing about the Bravo, we took right at gross, density altitude right around 7000, climb at 105 was still over 1000fpm.

 

Also,

 

Managed 5 go arounds this weekend for a total of 2 landings, including one bounce, bounce, bounce go around, yes, I was that "idiot" at KAPA on Friday afternoon;-) Wasn't my best day. With the turbulence there, I couldn't hold airspeed within 20 knots on final. Once a Mooney is behind the power curve, it ain't pretty, especially at high altitude. My XM must have died because all the time I was expecting 3 knots variable and when I finally pulled up ATIS, it was 15 gusting to 30. Went around 3 times, finally approached at about 95knots with the boards out and put her down. Airspeed indicator went from about 85 to 60 in two second in flare. Got to love the mountains on a windy day. The usual speed of 75knots plus gust factor just would not work, the bottom simply dropped out every time, big time. On the final landing, I still had some power in flare.

[The-sky-captain]

I've taken off at gross weight numerous times from Denver and Colorado Springs, in the summer, in my NA J with no issues. I'm usually off the ground before 11am or so. It took a few trips up there, with me gradually increasing the weight, before I attempted a full gross takeoff. During the winter she climbs like a bat outta hades, summer makes her a little more sluggish on the roll and climb out but it's manageable.

[KSMooniac]

You were wise to remove fuel.  I've done that too, even in the flatlands, after I was mistakenly topped off vs. my requested "to the tabs" order.  

[garytex]

Our Mooneys have lots of power compared to some of the groundpigs I have flown in the past, and you may very well have been able to wish her off 3/4ths of the way down the runway, and stager over surrounding terrain.  

However, the day you are just a little too heavy, there isn't quite enough runway left to stop, and the trees at the end of the runway look just a tiny bit taller than you can climb, generates that 'I have been irreparably stupid and am about to pay a price that I do not want to pay' feeling that reinforces the correctness of your no-go decision.  This is a lesson that can be learned either cheaply, or with lots of anguish.  High altitude airports minimize the apparent danger the and multiply the chances of getting caught.  You did the right thing, and those other guys may be experienced enough to get away with over gross operations, or they might just like flying enough to die for it.

We aren't teenagers anymore, and take a long time to heal.  And it smooth "taint fair" to leave our survivors in the lurch due to a moment of impatience.

 

Gary

[AndyFromCB]

So how much fuel does a 1990 Bravo hold when filled past the filler necks to the fuel caps? I'm just wondering if I downloaded enough. I assumed 95 gallons of usable but it might be 102? Anybody knows?

[John Pleisse]

Over gross is almost always possible, even flagrantly. Here's the rub. You limit any room for error. Forget the flaps on takeoff? You'll be real surprised when the nose shoots up and you are wobbling in ground effect. Sudden maneuvering? Keep your speed way up. Patterns? no more than 20 deg bank. Etc, etc.

 

You can do it all day (w/in reason), you just can't screw up, get slow or forget something.

[AndyFromCB]

Over gross is almost always possible, even flagrantly. Here's the rub. You limit any room for error. Forget the flaps on takeoff? You'll be real surprised when the nose shoots up and you are wobbling in ground effect. Sudden maneuvering? Keep your speed way up. Patterns? no more than 20 deg bank. Etc, etc.

 

You can do it all day (w/in reason), you just can't screw up, get slow or forget something.

 

That was my take as well when I told my significant other that we're not taking off. I never doubted the Bravo's ability to climb at 3550lb (we'd probably still see 900fpm or so) or even the ability to depart in the available runway (7000 feet of it). I was questioning the what if factor especially after my "performance" landing there on Friday.

[RJBrown]

The J sounds a little scary. 200# over in a TLS with 10,000' of runway at Centennial would not scare me.

[John Pleisse]

That was my take as well when I told my significant other that we're not taking off. I never doubted the Bravo's ability to climb at 3550lb (we'd probably still see 900fpm or so) or even the ability to depart in the available runway (7000 feet of it). I was questioning the what if factor especially after my "performance" landing there on Friday.

I think you made the smart call.

[jlunseth]

Well, you can't judge a book by its cover either.  I have sometimes flown with four people, usually two big guys and two ladies.  I give my guests a weight limit of 500, and with me the total payload is about #700.  But I do it only for short flights where I can carry much less than full tanks.  I have a useful load of over 980, so that still gives me a little over 45 gallons of fuel, enough for a couple of hours in the air and ample reserves at 15 gph (actual will be about 13 gph).  I have one tank filled, and the other carries whatever fuel is needed to make the gross weight limit (2900).  I burn off the full tank, and the other tank is my reserve.  No luggage though, I generally do this only for sightseeing flights.   Have done it several times.  Always uneventful.  Just need to make sure, with two full size people in the front, that the balance works out.  With the turbo, field altitude and temps are largely irrelevant, the only consequence of higher density altitude is a longer landing, but the high altitude airports nearly always have longer airstrips to accomodate that. 

[gjkirsch]

I am not going to second guess anyone's decision concerning taking off over gross weight.  If you take off in a Bravo right at gross weight, you are already above the maximum landing weight by 168 pounds.  I have been told that the gear will not pass the drop test at the maximum take off weight.  So, I assume that as long as you don't bounce down the runway landing, you probably won't do any damage.  I think all the Bravo owners know that the plane will still climb well with about anything you can jam in it.  Someone can probably comment on ferry flights to Australia taking off 1000 lbs over gross. 

 

Just remember that every time you take off outside what the manufacturer approves, you are now a test pilot. 

[aaronk25]

Mine is a 77 J with a gross of 2,740lbs.  I will operate that at 2,900. The only difference between the 77 and earlier J's is a stall speed 1 knot higher, a weight on the elevator and a tubing change that was to make the front end of the J's similar to the longer versions, to simplify mfg for mooney.  

 

There certainly could be consequences if there was a incident when over gross, even if it wasn't a direct result of the incident.  I will say I think its flat ass stupid that the earlier J's couldn't be STCd to the higher 2,900 weight.  Could it be that Mooney didn't want earlier J's displacing sales of later heavier models with a 1,140lbs useful load????   The single mag at 25degrees timing contributes to more overall hp than the newer j's at 20 degrees.  

 

I also fly this bird about 300 hours and I will say when the temps get in the 80's combined with higher altitude or if its raining (laminar flow wing is doesn't lift as well)  I start making very conservative decisions.  When its cool out up here in MN I don't necessarily even limit the plane to the gross weight, but you can bet I do when it get warmer. 

 

SR20 is same power and has 3,050lbs gross weight......I think Mooney left some money on the table when they certified the J.  Don't go out and overload your plane on my account, I'm just stating my opinion.

 

Sounds like you made a good decision with having them reduce fuel.  Its a must to be comfortable and absolutely confident that the plane will do what you need it to. 

 

 

Aaron

[N201MKTurbo]

Just make sure you have lots of runway, just saying.

[aviatoreb]

When I purchased my Mooney Rocket two years ago - the former owner was bragging that he once took off with seven people on board, and full fuel.  I kid you not.  First thing I did upon purchase was to change the gear pucks!  I have not taken off over gross but it is quite apparent from the tiny bit of ground roll and huge climb rate that it is a good lifter.

[Marauder]

When I purchased my Mooney Rocket two years ago - the former owner was bragging that he once took off with seven people on board, and full fuel. I kid you not. First thing I did upon purchase was to change the gear pucks! I have not taken off over gross but it is quite apparent from the tiny bit of ground roll and huge climb rate that it is a good lifter.

I would have loved to see a picture of that. Had to look like a stuffed phone booth attempt.

[RJBrown]

When I purchased my Mooney Rocket two years ago - the former owner was bragging that he once took off with seven people on board, and full fuel.  I kid you not.  First thing I did upon purchase was to change the gear pucks!  I have not taken off over gross but it is quite apparent from the tiny bit of ground roll and huge climb rate that it is a good lifter.

 

 

On the Rocket the gross weight is limited by gear strength not load lifting. With 35 more HP than the TLS it is limited to 168# less gross though it shares the same flying surfaces. At 3600# it will still outclimb a TLS. Landing is another story. The max landing weight is 3040#. At 140# more than the gross on a stock 231 it really is a limiting factor. I would consider the landing weight more significant than the gross weight. The conversion adds 200# most of it right over the nose wheel. When you land a Rocket you use only the mains till you are too slow to keep it up . A good landing is judged by how softly the nose gear touches down.

[M016576]

When I purchased my Mooney Rocket two years ago - the former owner was bragging that he once took off with seven people on board, and full fuel.  I kid you not.  First thing I did upon purchase was to change the gear pucks!  I have not taken off over gross but it is quite apparent from the tiny bit of ground roll and huge climb rate that it is a good lifter.

Talk about a clown car!!!

[M016576]

On the Rocket the gross weight is limited by gear strength not load lifting. With 35 more HP than the TLS it is limited to 168# less gross though it shares the same flying surfaces. At 3600# it will still outclimb a TLS. Landing is another story. The max landing weight is 3040#. At 140# more than the gross on a stock 231 it really is a limiting factor. I would consider the landing weight more significant than the gross weight. The conversion adds 200# most of it right over the nose wheel. When you land a Rocket you use only the mains till you are too slow to keep it up . A good landing is judged by how softly the nose gear touches down.

Did Rocket do any airframe or landing gear reinforcement? If not, then the structure itself is good up past 3040... STC for K models, anyone ;-) !

[aviatoreb]

Talk about a clown car!!!

 

I thought the same thing when he was telling me.  Imagine 7 clowns coming out of a mooney with big blow-up toys too just like at the circus.

 

Can you imagine the explainin' to do to the NTSB and the insurance company with 7 on board if it had not worked out?

 

As far as I know the M20K rocket has no structural reinforcement to either airframe of landing gear.  So the landing gear is the limiting factor for weights as RJBrown said, but there was an STC to increase weight to 3200 for take off as part of the rocket conversion stc - but not early in the stc I understand.  RJ knows this history well.  So mostly the stc is relying on the already stoudt airframe for flight.  But it is important to keep an suspicious eye on power descending in my opinion.

 

There was a M20M rocket conversion, and only 5 exist - much more rare.  It uses a 350hp liquid cooled continental - the "liquid rocket".  I have read reports that this airplane can true from 255 to 260tas according to various reports.  I was never able to find anything official on this conversion.  I do know that this conversion does include a number of gussets to strengthen the join points of the airframe flying surfaces to the fuselage - wings, tail and horizontal.  In principle that should raise the Vne but I wonder if the stc included the change to the airspeed indicator.

[aviatoreb]

Correct me if I am wrong, but isn't flutter a function of true airspeed and not indicated airspeed? I wonder at what point this becomes an issue with the M20 design? The margins must be pretty high, though, as I haven't heard of any of these high powered and high flying modified Mooneys losing their control surfaces, and it doesn't appear that changes to the control surfaces were part of the various Rocket conversions or even the TLS, Bravo, or the Acclaim.

Jim

 Quite right, it is a function TAS.  I do think from reading (but cannot confirm) that the M20M liquid rocket has gusset re-enforcements.  I don't know if they did this in reaction to a measured problem, or simply anticipating a possible problem.

 

If the design was way over engineered in the first place then a Rocket/TLS/Acclaim could be pushing closer to that margin but still be quite far from the margin.  

 

The most surprising high powered conversion is the Bonanza turbine conversion which has a top speed of 250TAS and that limit is the Vne rather than an inability of the high powered engine to push it even faster.  In other words you cruise right at Vne.  I understand that is common practice in turbines but this is a turbine that used to be a piston so it was designed with different considerations. Does anyone know if the Vne in a turbine was designed with a different margin in mind than in a piston, since Vne is also the top cruise speed?

[jetdriven]

Piston aircraft have a green arc and a yellow arc. The top of the green is where the airframe must withstand an instantaneous 30 FPS vertical gust at the certified load factor. This tapers off to 15 FPS at the design dive speed (10% above V_NE).  Turbine aircraft are built to much higher standards, they must withstand the 30 FPS gust at design dive speed.   Aircraft certificated after 1960 (CAR 3 aircraft) have 50 and 25 FPS limits.

 

The downside in the A36 turbine conversion (and the Piper Malibu) is the top of the green arc becomes the new placarded V_NE.  THe only way to get ay speed out of the things is to fly high.  Even so, at high altitude, the A36 turbine can still exceed the flutter margin at an IAS below placarded V_NE. IIRC there is a placard for maximum safe IAS at those altitudes.

[Piloto]

Correct me if I am wrong, but isn't flutter a function of true airspeed and not indicated airspeed? I wonder at what point this becomes an issue with the M20 design? The margins must be pretty high, though, as I haven't heard of any of these high powered and high flying modified Mooneys losing their control surfaces, and it doesn't appear that changes to the control surfaces were part of the various Rocket conversions or even the TLS, Bravo, or the Acclaim.

Jim

I did a GVT (ground vibration test) 20 years ago on a Mooney and found the wing will not flutter below 600kts. Unlike other singles this why you don't see Mooney wings coming apart in-flight. However this will not indicate the same for the empennage or cowling integrity.

One of the factors that limits gross weight is the stall speed in landing configuration. For single engine the stall speed can not be greater than 61kts in level flight. The other factor is the landing gear/tires strength. Adding weight increases the stall speed.

José

[jetdriven]

Someone has crashed a M20K Rocket before because of flutter. It was likely operating above V_NE. 

 

http://aviation-safety.net/wikibase/wiki.php?id=36780http://aviation-safety.net/wikibase/wiki.php?id=36780http://aviation-safety.net/wikibase/wiki.php?id=36780http://aviation-safety.net/wikibase/wiki.php?id=36780http://aviation-safety.net/wikibase/wiki.php?id=36780http://aviation-safety.net/wikibase/wiki.php?id=36780

[RJBrown]

There may be another limit to gross weight for the Rocket. Stall speed. According to Rockets spec sheet the stall speed is 61 knots at 3200# gross. More weight would push it over the certification limit. Initially the early Rockets were certified at 3040#. Mine was originally limited to 3040#. The change to 3200# involved a remarked ASI and paperwork similar to the J 2900# increase.

I believe the Rocket that crashed was coming down at over 3500 fpm and was above VNE in turbulence. 

Poor weather may have contributed to poor piloting. I could not follow the above link.

[Parker_Woodruff]

Correct me if I am wrong, but isn't flutter a function of true airspeed and not indicated airspeed? I wonder at what point this becomes an issue with the M20 design? The margins must be pretty high, though, as I haven't heard of any of these high powered and high flying modified Mooneys losing their control surfaces, and it doesn't appear that changes to the control surfaces were part of the various Rocket conversions or even the TLS, Bravo, or the Acclaim.

Jim

Yes, flutter is a function of TAS.

What's miserable is that the Rocket conversion didn't require new counterweights on the flight controls to my knowledge, but my Encore conversion did, just because it was on factory paper.

 

10 horsepower extra and 230 lbs more capacity on the Encore conversion.  95 horsepower and a heavy engine on the 305 Rocket Conversion.  Plus whatever weight increase was allowed.