Aux Tank option in M20J. How much fuel in Main before Crossover?

[Missile=Awesome]

58 minutes ago, N56394 said:

I'm convinced that the 71 arm is correct for the aux tank for the missile if the tank cap is just aft of the spar. I went out to the airplane and taped the main and from the diagram in my link from emapa I taped the aux tank. I estimated where the 48 arm would be for the main tank and then put a 2 foot level to see about where the 71 arm would be - yes it turns out to be at where I would guess the CG of the aux tank would be. I would double check your records to be certain. It is possible you all have different tanks, but can't hurt to double check. 

That is NOT where the Aux tank is located if you are choosing the back area of the wing.  Look at my photos in Missile Coming out Party.

[carusoam]

Welcome aboard 94...

There are a few variations of where exactly the tank foot print is in all the various Mooneys...

The O has 100 gallons, and when stretched it gets 130 gallons...

The arm in the tank doesn’t move...

To make this a true statement will require taking a pic inside the fill cap... the front of the tank is probably the main spar... the back of the tank is probably the sub spar...

The two spars are probably parallel to each other... since the discussion of tank shape is always rectangular, with a curved roof... on an angle...

Some extended tanks are actually a separate tank with space and connectors between them...

There is so much to know about your individual tanks... Drains, vents, sensors, connectors, sealants,  and caps and mechanical fuel gauges... and cap seals...

 

Very interesting question... from short to long body, 52 gallons to 130 gallons... there is one arm for all the fuel...

Unfortunately, José our fuel tank guy has had some health issues... but visits here somewhat often still...

Another resource to consider... Rocket engineering...  RE is an excellent resource.  Their documentation is stellar compared to many others.... RE is still in business, and still answers the phone, for some people...

Keep asking questions...

What took you so long to get to MooneySpace?
 

What part of Europe are you in?

Best regards,

-a-

[Missile=Awesome]

3 hours ago, carusoam said:

Welcome aboard 94...

There are a few variations of where exactly the tank foot print is in all the various Mooneys...

The O has 100 gallons, and when stretched it gets 130 gallons...

The arm in the tank doesn’t move...

To make this a true statement will require taking a pic inside the fill cap... the front of the tank is probably the main spar... the back of the tank is probably the sub spar...

The two spars are probably parallel to each other... since the discussion of tank shape is always rectangular, with a curved roof... on an angle...

Some extended tanks are actually a separate tank with space and connectors between them...

There is so much to know about your individual tanks... Drains, vents, sensors, connectors, sealants,  and caps and mechanical fuel gauges... and cap seals...

 

Very interesting question... from short to long body, 52 gallons to 130 gallons... there is one arm for all the fuel...

Unfortunately, José our fuel tank guy has had some health issues... but visits here somewhat often still...

Another resource to consider... Rocket engineering...  RE is an excellent resource.  Their documentation is stellar compared to many others.... RE is still in business, and still answers the phone, for some people...

Keep asking questions...

What took you so long to get to MooneySpace?
 

What part of Europe are you in?

Best regards,

-a-

They are both J’s with Missile conversion -a-  His doesn’t have the Monroy tanks...Mine does.  I’m stating that the AUX tanks are NOT where he is showing them on the wing with tape.  I don’t know if the speed brakes move the cap or what, but my tanks...the tanks he is interested in getting are NOT where the tape is.  We have had 75 gallons of fuel in the plane and I have trim right where he stated...Based on my CG we were within envelope.  With his 71?  NOPE.  Plane was fine as loaded with ZERO CG issues....So I am confused by the comments and the Rocket Engineering graph?  All I know...

[carusoam]

The O’s wing isn’t much different...

One thing that may have changed over time is the location of the speed brake...

Some planes have had the fuel tanks have a box-out for the brakes to keep them dry...

The O, has the brakes outside of the fuel tanks... other side of the main spar...(?)

 fuzzy memories at best.

+1 on verifying the proper drawing to match the exact plane...

Best regards,

-a-

 

[Missile=Awesome]

9 hours ago, carusoam said:

The O’s wing isn’t much different...

One thing that may have changed over time is the location of the speed brake...

Some planes have had the fuel tanks have a box-out for the brakes to keep them dry...

The O, has the brakes outside of the fuel tanks... other side of the main spar...(?)

 fuzzy memories at best.

+1 on verifying the proper drawing to match the exact plane...

Best regards,

-a-

 

Missile conversions were ALL to J or K airframes.  All Mid-Body.

[Missile=Awesome]

20 hours ago, N56394 said:

Thank you for that, so you are using the same arm for the aux tank as the main tank? I thought the aux was aft of the spar and the main was forward of the spar? My basic empty weight is 2206 lbs and arm is 42.2 so with that loading I would be over gross of 62 lbs and forward of the envelope corner at 45. Man, I need to lighten my plane, lol. I just looked at my records and found the ARM for the AUX fuel - look at the attached W&B from Rocket engineering - the AUX fuel is at ARM 71. Recomputing your loading with 64 gal mains and 26 gal aux would put me at an arm of 46 which would be within limits. ( I still need to shed 62 lbs though) Following your logic of half of the mains are used before the aux tank begins to feed that would be even better 32 gal mains and 26 gal aux would be an arm of 45.9 which is almost no change in arm. So this I think puts the mystery to bed. Just make sure you are using the arm of 71 instead of 48.43 for the fuel.

Our plane lost some serious weight with the removal of vacuum and old HSI/Attitude and install of dual G5’s.  The mains on our plane are 32x2 and Aux is 17x2=98 gallons.  Something is NOT right...

[Seth]

On 8/25/2020 at 11:27 AM, N56394 said:

I have a Missile 1983/2001 with speed brakes and am also interested in this discussion. As any Missile owner knows we are constantly flirting with the forward edge of the envelope. I have been trying to determine how adding these tanks affects the CG arm during the fuel burn. only data I can find so far is the 10-12 lbs @ 71 inches for the install weight and 15 gal per wing if speed brakes installed. If anyone can reveal the fuel arm for the Monroy aux tank it would be great. I have had the Missile for almost 20 years without the tanks, but am seriously considering the mod now as my flight mission is changing to visit kids far away.

I too have a Missile. I have the Aux tanks. Get the Monroy tanks while you still can. The flexibilty in having fuel for longer trips and not having to worry about thinking about stretching a fuel situation, or tanking up on cheap fuel, it makes a difference. Best speed mod you can do for your Missile.

-Seth

[Seth]

3 hours ago, Missile=Awesome said:

Our plane lost some serious weight with the removal of vacuum and old HSI/Attitude and install of dual G5’s.  The mains on our plane are 32x2 and Aux is 17x2=98 gallons.  Something is NOT right...

I have no speed brakes on my Missile. Also 32x2 (64) and 17x2 (34) = 98 gallons.

-Seth

[Missile=Awesome]

43 minutes ago, Seth said:

I have no speed brakes on my Missile. Also 32x2 (64) and 17x2 (34) = 98 gallons.

-Seth

Are you using 71 in your weight and balance computations?  I am not.  Our station for fuel is 48.3...

[Missile=Awesome]

46 minutes ago, Seth said:

I have no speed brakes on my Missile. Also 32x2 (64) and 17x2 (34) = 98 gallons.

-Seth

Any thoughts on “crossover” for fuel into AUX?  (Fuel level in Mains when crossover takes place and shows in AUX). I am thinking about 15-17 gallons in mains...Any more in mains and you see fuel in AUX.  Any less and the AUX tanks visually show “Bingo” Fuel.

[Seth]

Just now, Missile=Awesome said:

Are you using 71 in your weight and balance computations?  I am not.  Our station for fuel is 48.3...

I'll have to look. 

[M016576]

I think the issue here is in the use of the term “aux” tank.  I think the ferry tank (auxiliary tank) is what that document is referencing.  Not the Monroy Extended Range tank.  If only someone on this board could help us out @Piloto....

for your extended range tanks, the datam is the same as the regular tanks, correct.  48.43”.

[M016576]

On 8/25/2020 at 4:00 PM, N56394 said:

I'm convinced that the 71 arm is correct for the aux tank for the missile if the tank cap is just aft of the spar. I went out to the airplane and taped the main and from the diagram in my link from emapa I taped the aux tank. I estimated where the 48 arm would be for the main tank and then put a 2 foot level to see about where the 71 arm would be - yes it turns out to be at where I would guess the CG of the aux tank would be. I would double check your records to be certain. It is possible you all have different tanks, but can't hurt to double check. 

I know for a fact that their is no fuel that far aft in the wing, at least not where the extended range tanks are installed.... and if there is, you’ll need to go see Paul Beck @ weep no more.

[acekng1]

On 8/25/2020 at 11:33 PM, Missile=Awesome said:

They are both J’s with Missile conversion -a-  His doesn’t have the Monroy tanks...Mine does.  I’m stating that the AUX tanks are NOT where he is showing them on the wing with tape.  I don’t know if the speed brakes move the cap or what, but my tanks...the tanks he is interested in getting are NOT where the tape is.  We have had 75 gallons of fuel in the plane and I have trim right where he stated...Based on my CG we were within envelope.  With his 71?  NOPE.  Plane was fine as loaded with ZERO CG issues....So I am confused by the comments and the Rocket Engineering graph?  All I know...

On 8/27/2020 at 6:12 PM, M016576 said:

I know for a fact that their is no fuel that far aft in the wing, at least not where the extended range tanks are installed.... and if there is, you’ll need to go see Paul Beck @ weep no more.

 

I know this is an old thread but I've been investigating the arm for my extended range tanks on my 68F and wanted to add more info here in case others stumble on the thread.  According to the attached image, the long range tanks are actually installed aft of the main tanks.  The arm of 71 comes directly from the installation instructions for the tanks as shown in the second image.

The first image showing install location was pulled from here: https://www.emapa.aero/Monroy-Mooney-Fuel-Increase-Upgrade-p/mooney-fuel-increase-upgrade.htm

 

[carusoam]

Welcome aboard ace!

Nice first post.

Go MS!

Best regards,

-a-

[Pinecone]

I have seen that drawing before.   Thanks for the install page.

Using the arm for the main tanks only, I am OK, in my 252, on CG with 2 people and full fuel with the normal stuff in the baggage/hat rack area.  The issue with using the two arms is coming up with a table of how much fuel is in each for a given total.  I plan to do a run a tank dry, then fill 1 gallon at a time to make a dipstick to determine fuel.  But then I would need someone without Monroy tanks to do the same to be able to do a stick for the mains only.  

On my 252 with Monday tanks (with speed brakes) when the stock gauge reads 27 gallons, there is about 31 total in that wing.