Gross Weight Increase STC for J's

[Cruiser]

I am not sure of all the specific changes that occurred with the GW increase, but it would seem logical  that if you increase weight without increasing power or reducing drag your speed will suffer  

 

Just sayin'..........

[Awqward]

Yes...maybe that's why they stopped calling it a 205....with the increased GW they were back to 201mph!

[PTK]

Does anyone know what exactly it is those serial number Js have in common (and different than the rest) that makes them eligible for the GW increase?

I called a few years ago and spoke to the legend himself, Bill Wheat (rest his soul) about it. He indicated to me that it was paper work and an ASI swap. He didn't give a clearer answer than that. Is there something more than that like a structural difference? I'm trying to understand the reasoning.

I hear at times that 2740# planes being loaded up to the 2900# limit with no apparent negative impact. Not questioning the legality of this practice, it is ofcourse illegal, but what exactly is the difference?

[Smiles201]

My understanding, and I could be wrong, is that at some point the J model began to share the same basic tubing structure as the K model, which had a beefier construction. So there may be a structural difference that allows the higher gross?

 

[jetdriven]

Thing about that is the missile conversion Allows 3200 pounds gross weight to a stock J, no airframe or landing gear changes 

[ArtVandelay]

They probably just pulled a J from local used market , did some testing and presto, we have a new max gross weight, starting from whatever serial number. I believe one of the tests is a like 5 foot freefall drop, not something I want to try on my plane.  Probably some climbing tests as well.

[N601RX]

I think a couple of the tubes in the side were increased 1 sized in wall thickness 

[Piloto]

If there is going to be a strengthening of the structure due to weight increase it would be in the wings and landing gear but not on the fuselage tubing. Most of the weight is carried by the wing main spar. The most significant effect on weight increase is on climb performance, ceiling and take off run. With 200hp I think you are to the limit at 2900 pounds.

José  

[M016576]

4 hours ago, jetdriven said:

Thing about that is the missile conversion Allows 3200 pounds gross weight to a stock J, no airframe or landing gear changes 

The STC paperwork for my missile shows some new parts in the landing gear.  I'll take a picture and post it here... but I think, if an enterprising individual were to mod their older J with these parts, then DER test fly it for envelope expansion, they could create a STC for the 2900lbs increase... or maybe even more... on a stock J.

Edit-the original missile STC only rated the max GW of "pre-24-xxxx" serial number Js to 2900lbs.  A later update to the STC gave the 3200lb max gross.  Just saw that going through my logs.  Unclear if the later 3200lb update was enabled by the gear modifications, or if the gear mods enabled the 2900lb max gross.  The current logs/STC paperwork are at the hangar, so I'll have to wait till tomorrow or Monday to find the exact parts listed for the gear in the missile STC.  I'm fairly certain they are stock mooney parts from the K or maybe even a long body, just installed on the older J's.  but I'll be able to tell you for certain as soon as I relook at the STC packet.

Edited December 4, 2016 by M016576

[dlthig]

Has anyone contacted Rocket Engineering?

[PTK]

So to summarize:

• We have the Mooney 201 in two flavors: factory 200 hp and Rocket Engineering 300 hp.
• As per factory we have certain 200 hp sn's eligible for gw increase to 2900#.
•  Unclear as to why these certain 201s are eligible over the others.
• As per Rocket engineering all 201s are or were eligible for 3200# gw.
• GW difference of 300 # or a whopping 460 # on same airframe.
• The airframe can support, takeoff and clmb with up to 3200# gw according to Rocket Engineering.

An apparent disagreement between Mooney and Rocket Engineering. Am I correct?

 

 

 

[mike_elliott]

1 hour ago, PTK said:

So to summarize:

• We have the Mooney 201 in two flavors: factory 200 hp and Rocket Engineering 300 hp.
• As per factory we have certain 200 hp sn's eligible for gw increase to 2900#.
•  Unclear as to why these certain 201s are eligible over the others.
• As per Rocket engineering all 201s are or were eligible for 3200# gw.
• GW difference of 300 # or a whopping 460 # on same airframe.
• The airframe can support, takeoff and clmb with up to 3200# gw according to Rocket Engineering.

An apparent disagreement between Mooney and Rocket Engineering. Am I correct?

 

 

 

You got an answer but are choosing to ignore it. There were some tubes changed that were stronger to support the GW increase per what I have been told by those that should know.

[PTK]

15 minutes ago, mike_elliott said:

You got an answer but are choosing to ignore it. There were some tubes changed that were stronger to support the GW increase per what I have been told by those that should know.

Perhaps you misunderstood my post. What tubes were changed by Mooney for the 2900# gw?  Certainly no tubes were changed by Rocket Engineering other than the engine mount for the 3200# gw.

[1964-M20E]

While legally we are bound to our certificated gross weighs, in my case 2,740 pounds, it is clear that any 200HP Mooney can handle 2,900 pounds and take off with a longer take off run, slower climb and higher stall speed.  Other than fuselage length the air frames for the E, F and J's are the same aerodynamically when it comes to producing lift.  This would be ignoring the possibility of greater wear on landing gear parts.

The extra 100hp in the rocket is needed to get the 3200lbs up and away in many different conditions.  Again the M20 air frame can handle it and you probably could get away with 3200lbs at sea level on a nice cool day in a 200HP model but I would not want to try it especially under high DA conditions.

In effect you make yourself and your passengers test pilots with varying degrees of risk.

 

[mike_elliott]

2 hours ago, PTK said:

 

So to summarize:

• We have the Mooney 201 in two flavors: factory 200 hp and Rocket Engineering 300 hp.
• As per factory we have certain 200 hp sn's eligible for gw increase to 2900#.
•  Unclear as to why these certain 201s are eligible over the others

 

 

40 minutes ago, PTK said:

Perhaps you misunderstood my post. What tubes were changed by Mooney for the 2900# gw?  Certainly no tubes were changed by Rocket Engineering other than the engine mount for the 3200# gw

Perhaps I misunderstood what you wanted to ask, but didn't ask. You were "unclear as to why these certain 201's are eligible over the others" which was answered. What you now are asking is which tubes were changed vs what was changed. Do I have it correct now? Have you asked Mooney or Rocket? I am sure Dmax would know also.

[carusoam]

We may be mixing in physical strengths with flight characteristics in this topic...

Climb rate and T/O roll are a function of the power to weight ratio. Adding weight without adding power makes the trees at the end of the runway appear larger in the windshield.

From examples found around MS...

Adding 10% more HP (280 to 310hp) really trims the T/O run of the LB.  Book values go from 1200' to 800'.  This is done for the O1 to the O3 with very little difference in WnB...

Adding 50% more HP, like the Missile has, will really effect how much weight it can get off the ground.

It is also important to know your WnB details on this, as the Missile gains some additional weight on the nose. I believe the tail feathers on the LB may have been enlarged to help in this area...?  Check the POH for dimensional drawings of the horizontal stabilizer...

Our friend Patrick defined the limits of the M20J's ability to climb at MGTW on a warm day...

Our unknown pilot who put the fifth passenger in the baggage compartment of his M20C defined how goofy and dangerous some simple ideas can get.

Briefly,  adding a few hundred pounds to the plane makes it a challenge to get off the ground.  If the Cg is at the front of the envelope, the additional drag generated by the up elevator works against the available power...

When doing this on a hot day where power and lift are affected by the lower air density, know your performance limitations and make sure there is enough runway before pushing the knobs in....

PP ideas only, not a CFI...

Best regards,

-a-

 

 

[mooniac15u]

2 hours ago, PTK said:

Perhaps you misunderstood my post. What tubes were changed by Mooney for the 2900# gw?  Certainly no tubes were changed by Rocket Engineering other than the engine mount for the 3200# gw.

The tube numbered 26 in the diagram was upgraded starting with s/n 24-1686 which is the effective s/n for the 2900 lb gross weight increase.

[Oldguy]

1 hour ago, mike_elliott said:

 

Perhaps I misunderstood what you wanted to ask, but didn't ask. You were "unclear as to why these certain 201's are eligible over the others" which was answered. What you now are asking is which tubes were changed vs what was changed. Do I have it correct now? Have you asked Mooney or Rocket? I am sure Dmax would know also.

I am going to ask a question Peter's post has made me consider: I get the 2740# to 2900# GTOW increase in the standard J (larger diameter tubes), and I understand an increase with the Rocket mod. What I do not understand is the lack of different GTOW in a 2740# Rocket J and a 2900# Rocket J. Are the later 2900# J's being penalized or are the 2740# J's getting an increase they (on paper) should not have received? It appears the STC treats both airframes equally, which leads to the question of why the weight limitations are different with the stock 200 hp engine.

Clear as mud?

Edited December 7, 2016 by Oldguy
Typo.

[carusoam]

Rocket engineering produced the full paperwork to go with their STCs...

This allows them to demonstrate the variables of the system with their STC.

It is possible that the Mooney factory was dragging their feet when it comes to demonstrating the value of simple updates.

Proving a tube change is all that is needed to bring an older airframe up to new airframe standards was unhelpful to their new airframe sales business.

Changing out that tube is a difficult procedure.  Having to generate an STC to do it can be expensive.  We have a couple of people around here familiar with the STC process...  

When it comes to airframe strength, the defined maneuvering speed vs. weight chart will be of interest. Does the yellow zone on the airspeed indicator change with sn 1686 as well?

The plane has to stall before it breaks itself.  The lighter the plane the lower this speed becomes...

The nose wheel has to be able to handle a solid landing of the max weight.

Broken Mooneys upon landing are typically a collapsed nose wheel strut.

That lower tube, is that the one that sees the most rust damage when rainwater enters the cabin over time?

PP Ideas that come to mind on this subject... not a CFI or a mechanic.

Best regards,

-a-

[mooniac15u]

19 minutes ago, Oldguy said:

I am going to ask a question Peter's post has made me consider: I get the 2740# to 2900# GTOW increase in the standard J (larger diameter tubes), and I understand an increase with the Rocket mod. What I do not understand is the lack of different GTOW in a 2740# Rocket J and a 2900# Rocket J. Are the later 2900# J's being penalized or are the 2740# J's getting an increase they (on paper) should not have received? It appears the STC treats both airframes equally, which leads to the question of why the weight limitations are different with the stock 200 hp engine.

Clear as mud?

On the FAA website the Missile conversion STC is dated 1992 and the gross weight increase STC for the conversion is dated 1997.  That's well after Mooney increased the certified max gross weight.  It seems likely that Rocket Engineering used the current gross weight data at the time when applying for the STC.  The earlier J's probably got approved as part of the STC because nobody in the approval chain knew there was a difference.

[PTK]

1 hour ago, mooniac15u said:

On the FAA website the Missile conversion STC is dated 1992 and the gross weight increase STC for the conversion is dated 1997.  That's well after Mooney increased the certified max gross weight.  It seems likely that Rocket Engineering used the current gross weight data at the time when applying for the STC.  The earlier J's probably got approved as part of the STC because nobody in the approval chain knew there was a difference.

Regardless there's no Mooney breakup in flight that I know of except one that got caught in a TS. Are there any others?

Are there any M20J in-flight breakups attributed to GTOW overage? Stock or converted?

 

[ArtVandelay]

2 hours ago, PTK said:

Regardless there's no Mooney breakup in flight that I know of except one that got caught in a TS. Are there any others?

Are there any M20J in-flight breakups attributed to GTOW overage? Stock or converted?

There are 3 breakups, non attributed to over weight,

1J and 2 Ks

231BY, 5788U, 5809J...don't know year of J but it was #1554

Edited December 7, 2016 by teejayevans
Clarification

[mooniac15u]

44 minutes ago, PTK said:

Regardless there's no Mooney breakup in flight that I know of except one that got caught in a TS. Are there any others?

Are there any M20J in-flight breakups attributed to GTOW overage? Stock or converted?

 

What's your point?  First you ask why the difference, which Mike answered.  Then you ask which tube, which I answered.  Now you are asking whether it matters?

[AndyFromCB]

1 hour ago, teejayevans said:

There are 3, 

1J and 2 Ks

231BY, 5788U, 5809J...don't know year of J but it was #1554

Breakups, or breakups attributed to being over gross? You'd have to take off at twice the legal weight in a J in order to even stand a chance to breaking up due to G loading. I'm pretty positive Mooney breakups are due to overspeed events not overloading events. The K that got into a TS over Lincoln, NE was so bent when it landed that Mooney factory was called in and stated the aircraft experienced an 11G upset. Wing tips were a foot higher upon landing than they were on takeoff. Don't overspeed and you will not lose your tail. You'll never lose your wings in a Mooney. They'll be there to help you make a larger crater in the ground.

As to departing overgross, ever seen a Beech A36 depart at 4024 (legal weight with 300hp engine and short, fat wings). I see no reason why a long body Mooney cannot do the same considerably more safely than a A36. Now, I would not want to land one over gross, whereas a Beech A36 can probably land at 5500lb without an issue being the gear is same as the Baron.

An 310hp Acclaim still has a better power to weight ratio at 4000lb than a J at 2740lb, so it will out climb it. My old Bravo never had issues departing with 3 fatties aboard and full fuel and never used up more than 2500ft on take off (that was always my cut power and start breaking point, never even came close). The issue is landing gear. Replace it with struts and Mooney would have a hell of a plane that could compete against Cirrus. 4 fatties and full fuel. Do what Piper did and install VGs in order to keep stall speed below 61knots at 4000lb.

There are many different ways to die in a GA aircraft, being few hundred pounds over gross on a typical long runway is the least of one's worries. 

Edited December 7, 2016 by AndyFromCB

[mooniac15u]

1 hour ago, bluehighwayflyer said:

I think that Peter's point is that Rocket Engineering appears to have managed to get an across-the-board 3200 pound gross weight approved by the FAA by STC for the Missile conversion without distinguishing between J serial numbers, which calls into question the relevency of the tube change that coincides with the 2900 J gross weight increase. Not to speak for him, of course.

I suppose that one way to look at it is that because Rocket Engineering got an STC for a 300 lb increase it means that the original thinner tube can handle the weight.  The counter to that viewpoint is that the engineers at Mooney appear to have felt that a stronger structure was needed.  The former is largely regulatory and the latter is hopefully based on in-depth knowledge of the airframe.

Either way I don't think the issue is catastrophic failure from a single flight with an extra 300 lbs.  It seems more likely that the concern was the long term stress on that tube.  What does that mean in terms of the pre 24-1686 M20Js with the Missile conversion?  There probably aren't enough of them to know yet whether the increased load on that tube will lead to failure.

Rather than assuming that the Missile STC validates an increased GW in my early M20J I would personally be more concerned about the long term potential for issues with early M20J Missile conversions.  If I owned one I would make sure my IA looked carefully at that tube and its associated welds at each annual.