Mooney Missile CG

[1980Mooney]

On 4/30/2021 at 11:20 PM, Rspencer612 said:

Hey all,

I have acquired a BEAUTIFUL M20J Missile conversion. Sadly the airplane logs were lost and it spent some time sitting. We have re complied with all the AD’s and finished the annual inspection and discrepancies. 

I assume you know the plane geared-up in ‘06 and porpoised into the runway in ‘09. 
 

[Rspencer612]

On 5/2/2021 at 2:21 PM, 1980Mooney said:

A couple comments and questions:

I see some pics of your plane online. 

SARLTaylor-N4262H-64.jpg | Sport Air Racing League (sportairrace.org)

KGYI-MooneyM20-N4262H-71.jpg | Sport Air Racing League (sportairrace.org)

Your cowling doesn't have the ram air found on most Missile conversions like this:

Do you have extended range Monroy tanks?  I assume you do not since your A&P used 64 gal in his calculation.

Where did your A&P get the Arms?  The POH says the wheelbase is 5 ft. 11 9/16 inches or 71 9/16 inches.  The nose wheel center should be 5 inches in front of the Reference Datum (service manual says should be within 0.06 inches of plumb line from nose gear trunnion which is station -5.  See 32-50-02).  That means the Main Gear Arm is 66 9/16.  Your A&P used 64.  Are your nose gear discs collapsed and the nose wheel displaced back?

 

 

My Missile was weighed by Rocket.  2,169 lbs empty and CG 41.63 inches.  I have a standby vac in the tail which adds weight.

It is inconceivable that your Mooney is that far out of forward balance.  However I see all these pics of it racing.  Do you think someone took the weights out of the tail for some sort of speed mod?

Regarding Rocket - mine was one of the last Missile conversions.  It was done in 2001.  They hadn't done any in a while at the time and they actually made a mistake setting up the IO-550.  They had to get the Continental Rep out to help remind them - I was there when it happened.  Their focus even in 2001 had almost entirely shifted to turboprop conversions of Piper Malibu's. There are some threads here saying Rocket committed to support the STC for 17 years - not sure from when but the last Missile or Rocket was done 20 years ago.  They support as a curtesy now but let's be realistic - they haven't worked on a Mooney or internal combustion engine in 20 years.  There probably are few if any employees still there that actually turned a wrench on a Mooney. Darwin Conrad is in his 70's.  Whoever is helping you has to go dig in the files.

 

You make a lot of good points here. So let me do my best to answer them. Sorry for being off yesterday, had to work. 
 

Yes those pictures are accurate of the plane, and no it does not have that cool Ram air snout yours has. It was Rocket serial 300.0014, my guess is one of the earlier Missile conversions. Plane is serial 24-0688. The engine air intake is behind the cylinders pilot side, and I wondered if that design could have been more efficient for cool ram air. Your picture and plane shows they solved that. 
 

I do not have the Monroe tanks, standard 64 gallon wet M20J wing. I do have 12V precise flight speed brakes. 
 

I am also suspect of my A&P’s measurements. Don Maxwell told me he used 65 inches on his previous Missile conversion. I wonder with yours being a much newer conversion if it’s a bit longer, but I think that needs another look. 
 

the landing gear rubber discs are well in spec and actually appear and measure like new. No sag at all. 
 

I thought it inconceivable as well. I started by, verifying the math, then calculating wether a minor difference in 64,65,66 on the gear measurement could account enough for the GROSS imbalance. The answer was it absolutely helps move the CG aft, but still not enough to offset the gross imbalance. 
 

last night my A&P called, I’m the road flying the boss’s jet. He told me there are no Charlie weights anywhere in the tail of the aircraft including beyond the batteries over the jack screw where Rocket suggested they should be. I do believe that maybe the previous owner removed the weight because he did race it!  But I wonder why?  The extreme forward imbalance would create drag and I think would have slowed the plane more than any speed increase from a loss of 19-30lbs, although I’m not an engineer and that’s a guess based on basic knowledge of aerodynamic principles I have......

 

I have emailed Rocket again today because now I need to find/buy the correct replacement Charlie Weights, and we need drawings for the install. Wish me luck as I feel this task could get hard...........

Secondly I am going to have it re weighed, likely de fuel it with much closer attention to detail on the measurements after we get the Charlie weights installed.  If we are off 1-2 inches there, and add the appropriate (19-30lbs) weights in the tail, then we might have enough to get it back to a proper usable CG to match what it had originally and was STC approved as.

Now also get Rocket to iron out which actual max gross and max landing weights apply to this conversion.......What a headache.  Lol

 

Here’s to fingers crossed it’s so much fun to fly and so fast, all this headache is worth it!  

 

Edited May 3, 2021 by Rspencer612

[Rspencer612]

On 5/2/2021 at 4:00 PM, 1980Mooney said:

I assume you know the plane geared-up in ‘06 and porpoised into the runway in ‘09. 
 

Yes I did, I acquired all available history I could locate on the plane during the purchase process. Additionally, I have gathered info to indicate a third incident of a prop strike in 2010. 
 

This is additional supporting factors that make me think this CG is actual, and not inconceivable. A modification not in compliance with the STC, now created a VERY forward CG and the results are prop strikes and porpoises?

[A64Pilot]

I would add the weight to the tail mathematically, and see if that fixes everything, 30 lbs with that much arm is a whole lot of moment so I think it will make a large difference.

‘So far as accounting for what people do, I gave up on that long ago, some have strong beliefs and they just can’t let them go.

‘I’d tell you from flight testing that ballasting to aft CG almost always increases speed, even though you added weight

[carusoam]

The Mooney factory will have a record of the ballast that was installed in the plane by serial number... as an M20J it may only have been a couple of pounds mounted as far back in the fixed tail cone...

Rockets and Missiles got a pair of batteries put deep into the tail... changing out a battery uses a battery board to help transport it into the position....  check to see if you have a pair of batteries way back...

It sounds like this plane may have been out of balance for a while...

Being far forwards in the envelope... expect the elevator to use a high AOA as the speed bleeds off... when it stalls, the nose drops to meet the runway...

 

Every Mooney owner knows that setting the WnB up for best speed puts the dot on the back of the envelope...

Without the B... the elevator required to compensate causes too much aerodynamic drag...

 

Really cool to get this figured out before the next tail stall occurs... 

This is going to go in the really weird file if somebody actually removed weights to go faster and messed up the B part of WnB...

WnB are Attached at the hip... that’s why it isn’t just W or B...

There are even apps written about it...

Best regards,

-a-

[ArtVandelay]

The Mooney factory will have a record of the ballast that was installed in the plane by serial number... as an M20J it may only have been a couple of pounds mounted as far back in the fixed tail cone...
Rockets and Missiles got a pair of batteries put deep into the tail... changing out a battery uses a battery board to help transport it into the position....  check to see if you have a pair of batteries way back...

Technically I don’t classify them as Js anymore, which brings up the question if you want to install a GFC 500 , I don’t think the normal installation wouldn’t work with the 2 batteries and battery board.

[A64Pilot]

I don’t know anything about Rockets and Missiles, but if they were a J to start with, unless the data plate has been replaced or more often another one added, then they are still a J. This becomes important for things like STC’s etc.

[Rspencer612]

13 hours ago, carusoam said:

The Mooney factory will have a record of the ballast that was installed in the plane by serial number... as an M20J it may only have been a couple of pounds mounted as far back in the fixed tail cone...

Rockets and Missiles got a pair of batteries put deep into the tail... changing out a battery uses a battery board to help transport it into the position....  check to see if you have a pair of batteries way back...

It sounds like this plane may have been out of balance for a while...

Being far forwards in the envelope... expect the elevator to use a high AOA as the speed bleeds off... when it stalls, the nose drops to meet the runway...

 

Every Mooney owner knows that setting the WnB up for best speed puts the dot on the back of the envelope...

Without the B... the elevator required to compensate causes too much aerodynamic drag...

 

Really cool to get this figured out before the next tail stall occurs... 

This is going to go in the really weird file if somebody actually removed weights to go faster and messed up the B part of WnB...

WnB are Attached at the hip... that’s why it isn’t just W or B...

There are even apps written about it...

Best regards,

-a-

The weights definitely are not there, and Rocket says they should be. So let’s put this on the really weird file!  Lol

yes, I replaced both 35 series batteries in the tail  they are WAY back there in that custom sliding tray.

And this balance issue is EXACTLY why I did not fly it after getting it in annual, ground runs, and completely ready, scaling it was last thing and paperwork required and viola, a major issue.  I don’t want a tail stall, and I appreciate proper flight characteristics.  It’s grounded until we resolve. Balance is really important and I believe this has been a major factor in this planes incident history!

Edited May 4, 2021 by Rspencer612

[Rspencer612]

40 minutes ago, A64Pilot said:

I don’t know anything about Rockets and Missiles, but if they were a J to start with, unless the data plate has been replaced or more often another one added, then they are still a J. This becomes important for things like STC’s etc.

Another data plate is added by Rocket next to the Mooney data plate. It has both a factory serial number and a Rocket serial number.

Both Mooney and Rocket drawing’s apply. The airplane remains a 12v system, the battery just adds ballast and give the benefit of increased capacity VS just Charlie Weights. I would doubt that would create ANY issue with a GFC500 install or anything else as suggested above..........

[ArtVandelay]

Another data plate is added by Rocket next to the Mooney data plate. It has both a factory serial number and a Rocket serial number.
Both Mooney and Rocket drawing’s apply. The airplane remains a 12v system, the battery just adds ballast and give the benefit of increased capacity VS just Charlie Weights. I would doubt that would create ANY issue with a GFC500 install or anything else as suggested above..........

I would think the sliding battery board would prevent the normal trim/elevator servo installation:
Here is the J installation, where would the battery board go?

[aviatoreb]

5 minutes ago, ArtVandelay said:

I would think the sliding battery board would prevent the normal trim/elevator servo installation:
Here is the J installation, where would the battery board go?

 

Strangely, I think that the STC rocket or Missile does not interfere with the STC GFC500 as a matter of paper work, but it is indeed plausible the installations may physically interfere.  Surely the FAA has some reg to cover such interference if one occurs?  

I do believe I have seen someone on here did a GFC500 install on a rocket, with the usual M20K STC for GFC500, and I don't remember hearing any issue of interference if there was one.  Is the battery setup on the missile identical to that on the rocket?

[Hank]

1 hour ago, Rspencer612 said:

Another data plate is added by Rocket next to the Mooney data plate. It has both a factory serial number and a Rocket serial number.

Both Mooney and Rocket drawing’s apply. The airplane remains a 12v system, the battery just adds ballast and give the benefit of increased capacity VS just Charlie Weights. I would doubt that would create ANY issue with a GFC500 install or anything else as suggested above..........

Rocket and Missile conversions are not your ordinary STCs . . . . .

[RJBrown]

2 hours ago, ArtVandelay said:

I would think the sliding battery board would prevent the normal trim/elevator servo installation:
Here is the J installation, where would the battery board go?

The sliding battery board is a tool. It is not part of the airplane. It makes battery installation easy. It does not stay in the plane. It would in no way affect anything.
Other installed equipment may make battery installation and service more difficult.

[A64Pilot]

4 hours ago, Hank said:

Rocket and Missile conversions are not your ordinary STCs . . . . .

That statement doesn’t really mean anything, what’s “normal”

As far as I know if you change the model of aircraft, the data plate changes or more often I believe there is another data plate put on beside the original.

‘If that doesn’t happen, then the model of the aircraft didn’t change and things like STC’s if applicable can be installed, it’s up to the responsibility of the installer to determine applicability and suitability of the STC on that aircraft, and other installed STC’s.

‘If it becomes something other than a J and you want to install a radio for instance that has J models listed, but not the new model of your aircraft, then your going to have to have another approval method.

I’d suspicion that even with the big motor and different prop, multiple batteries etc, it’s still a J model.

Edited May 4, 2021 by A64Pilot

[A64Pilot]

5 hours ago, Rspencer612 said:

Another data plate is added by Rocket next to the Mooney data plate. It has both a factory serial number and a Rocket serial number.

Both Mooney and Rocket drawing’s apply. The airplane remains a 12v system, the battery just adds ballast and give the benefit of increased capacity VS just Charlie Weights. I would doubt that would create ANY issue with a GFC500 install or anything else as suggested above..........

Just read your post. If the model is different and it sounds as if it may be, then your going to have to use another approval method than the STC, unless the STC has the new model listed.

‘Knowing nothing about it, I’d suspect it to not be an issue though. With avionics it’s extremely common to install equipment that’s not covered by an STC, avionics shops pretty much have an inspector on speed dial and they have worked together so much that the shop already knows what they want, and the inspector knows they supply what he wants to see etc,. they have a working relationship, so it’s not big deal, usually. Most often the shop can tell you up front if it’s going to be hard or not.

‘If an STC doesn’t cover it, then a field approval is the way

‘It can be a big deal for a mechanic that doesn’t have that working relationship though, I’ve seen paperwork go back and forth several times and each time it reenters the que and it may be a few weeks before the inspector reviews it, marks it up and sends it back, then the process repeats.

Edited May 4, 2021 by A64Pilot

[missile]

 

I love this topic as I have recently acquired a missile and my W&B is in question.

I glanced over the topic and could not find your reference to the 70 pound weight in the baggage department. I understand it is part of the STC. and is required for single pilot operation. my serial # is  24-0953

I am very interested in your pursuit for the perfect W&B.

keep in touch

Missile John

[1980Mooney]

23 hours ago, aviatoreb said:

Strangely, I think that the STC rocket or Missile does not interfere with the STC GFC500 as a matter of paper work, but it is indeed plausible the installations may physically interfere.  Surely the FAA has some reg to cover such interference if one occurs?  

I do believe I have seen someone on here did a GFC500 install on a rocket, with the usual M20K STC for GFC500, and I don't remember hearing any issue of interference if there was one.  Is the battery setup on the missile identical to that on the rocket?

That Garmin Autopilot assembly will absolutely interfere with the placement of the battery board.  The batteries are in a box that is aft of those servos in the picture.  The box with 2 batteries weighs about 70 lbs.  You have to take the entire box out - the individual batteries are not accessible.  A 3 ft. battery board spans the distance from the edge of the shelf holding the box to span holding the autopilot assembly in your pic.  You or your A&P have to crawl into the tail laying on the board in order to unbolt the box and then slide it forward on the board.

That Garmin Autopilot assembly looks flimsy enough that it will bend over if you put the Battery Board on top of it.  It is possible that someone installed a GFC500 in a Missile/Rocket without thinking about the battery box.  The only time I need to get to the batteries is to replace them about every 5 years or more.  It just means that they have to remove that Garmin Autopilot Assembly in the pic in order to access the batteries.  And that means more shop hours, time, money and potential problems due to disturbing everything.

 

[aviatoreb]

8 hours ago, 1980Mooney said:

That Garmin Autopilot assembly will absolutely interfere with the placement of the battery board.  The batteries are in a box that is aft of those servos in the picture.  The box with 2 batteries weighs about 70 lbs.  You have to take the entire box out - the individual batteries are not accessible.  A 3 ft. battery board spans the distance from the edge of the shelf holding the box to span holding the autopilot assembly in your pic.  You or your A&P have to crawl into the tail laying on the board in order to unbolt the box and then slide it forward on the board.

That Garmin Autopilot assembly looks flimsy enough that it will bend over if you put the Battery Board on top of it.  It is possible that someone installed a GFC500 in a Missile/Rocket without thinking about the battery box.  The only time I need to get to the batteries is to replace them about every 5 years or more.  It just means that they have to remove that Garmin Autopilot Assembly in the pic in order to access the batteries.  And that means more shop hours, time, money and potential problems due to disturbing everything.

 

Huh - thanks for that detailed analysis.

So to summarize if I understand?  The rocket/missile batteries are behind where the gfc500 goes and so its not physically interferring but becomes impossible to access - without essentially removing part of the gfc500?

It would be nice if there were an access port on the side of the tail, like a hole in the skin.

Well for what its worth, on battery minder full time, my batteries last a healthy service life of 12 yrs - concords - and I just replaced them last summer.

[1980Mooney]

15 hours ago, missile said:

 

I love this topic as I have recently acquired a missile and my W&B is in question.

I glanced over the topic and could not find your reference to the 70 pound weight in the baggage department. I understand it is part of the STC. and is required for single pilot operation. my serial # is  24-0953

I am very interested in your pursuit for the perfect W&B.

keep in touch

Missile John

There is no "70 pound weight in the baggage compartment" in the STC.

Mooney Missiles are modified by the following STC's

• SA00081SE Engine, Prop
• SA00472SE Weight 
• SA00260SE Cowling
• SA4443NM Gap Seals and Speed Fairings
• SE00223SE Oil Drain Valve

They say nothing about 70 lbs. in the baggage compartment.

Your plane, however depending on configuration and/or alteration, may have a weight and balance issue that requires it.  My plane has Monroy Long Range Tanks and a standby vacuum pump in the tail which add weight behind the CG.  Also the Monroy tanks allow some fuel to distribute aft of the main tanks.  My Serial Number is close to yours and I have no problem with Single Pilot CG and I do not fly with extra weight in the baggage area.  

 

Edited May 5, 2021 by 1980Mooney

[carusoam]

Find the reference for 70LBs...

and copy it or highlight it some how...

Sounds like it is mis-understood between at least two people...

Expect a certain amount of weight to be used in the baggage area by many Mooniacs...

a normal WnB alteration for speed and tools...

not for adjusting serious WnB challenges...

Best regards,

-a-

[Hank]

5 minutes ago, carusoam said:

Find the reference for 70LBs...

and copy it or highlight it some how...

Sounds like it is mis-understood between at least two people...

Expect a certain amount of weight to be used in the baggage area by many Mooniacs...

a normal WnB alteration for speed and tools...

The post above read to me like 70lb in baggage was supposed to be part of the STC requirements rather than a speed-enhancing rearward CG shift. Sounded weird to me too.

[Rspencer612]

23 hours ago, missile said:

 

I love this topic as I have recently acquired a missile and my W&B is in question.

I glanced over the topic and could not find your reference to the 70 pound weight in the baggage department. I understand it is part of the STC. and is required for single pilot operation. my serial # is  24-0953

I am very interested in your pursuit for the perfect W&B.

keep in touch

Missile John

Are you talking about the 70lbs of weight the dual batteries provide from the STC way aft of the baggage compartment?  I don’t know of any baggage weights. 
 

Darwin from Rocket emailed me today, we aren’t sure who re over the weights at the 197.5 station, but they were there when they built it. He says they have them so I am waiting for his reply and price and shipping time!

[Rspencer612]

8 hours ago, 1980Mooney said:

That Garmin Autopilot assembly will absolutely interfere with the placement of the battery board.  The batteries are in a box that is aft of those servos in the picture.  The box with 2 batteries weighs about 70 lbs.  You have to take the entire box out - the individual batteries are not accessible.  A 3 ft. battery board spans the distance from the edge of the shelf holding the box to span holding the autopilot assembly in your pic.  You or your A&P have to crawl into the tail laying on the board in order to unbolt the box and then slide it forward on the board.

That Garmin Autopilot assembly looks flimsy enough that it will bend over if you put the Battery Board on top of it.  It is possible that someone installed a GFC500 in a Missile/Rocket without thinking about the battery box.  The only time I need to get to the batteries is to replace them about every 5 years or more.  It just means that they have to remove that Garmin Autopilot Assembly in the pic in order to access the batteries.  And that means more shop hours, time, money and potential problems due to disturbing everything.

 

We do not have the battery board. My A&P crawled into the tail having to be very cautious of we distributed his body weight and the battery weight. We passed out two old ones. And in went 2 new batteries. No issues. Bet that board would have made it A LOT easier. Haha 

[Rspencer612]

8 hours ago, aviatoreb said:

Huh - thanks for that detailed analysis.

So to summarize if I understand?  The rocket/missile batteries are behind where the gfc500 goes and so its not physically interferring but becomes impossible to access - without essentially removing part of the gfc500?

It would be nice if there were an access port on the side of the talk, like a hole in the skin.

Well for what its worth, on battery minder full time, my batteries last a healthy service life of 12 yrs - concords - and I just replaced them last summer.

Yes the batteries are in a box AFT of where the servo would be go. It would be in the way for a battery board. Or a battery replacement. But until I see an installed one, I’m not convinced you would have to remove it completely to change batteries based on how we just changed mine........

[1980Mooney]

49 minutes ago, Rspencer612 said:

We do not have the battery board. My A&P crawled into the tail having to be very cautious of we distributed his body weight and the battery weight. We passed out two old ones. And in went 2 new batteries. No issues. Bet that board would have made it A LOT easier. Haha 

Make one. It has been discussed here before. Rocket and Missile Battery Boards are identical. 

 

 

Edited May 6, 2021 by 1980Mooney