GT 27FB Twin Cargo Capacity Challenges. Need Help!!

[Cracker10]

Just took pictures and my 2020 Globetrotter 27FB Twin shows the same 3800#, will also post the tire ratings

[foobar]

Originally Posted by Cracker10

Just took pictures and my 2020 Globetrotter 27FB Twin shows the same 3800#, will also post the tire ratings

Thanks Cracker!

Looks like your trailer is lighter by a couple of hundred lbs (6460lbs) vs a 2022 for which I just snagged the data (6674 lbs). Do you have any factory installed options like a 2nd A/C unit?

[s1000pre]

Cracker10 doesn’t have composite floors. That’s gotta be 200lbs.

[Cracker10]

Only options different on 22 models are composite floor, 12 volt fridge, and on demand water heater. All Globetrotter 27's come with two AC's

[guskmg]

I would ask Airstrem Service @ JC about these mods because on the longer trailers especially, frame cracking can become a problem. I would ask service just to be sure.
guskmg

[Rickeyt]

I have a 2022 Globetrotter 25FBQ and the Dexter axels are #11 capacity 3800 lbs.
The following is from the owners manual.
When a trailer is properly hitched up to a tow vehicle
with a load equalizing hitch, approximately 1/3 of the
trailer’s tongue weight will be on the trailer’s axles
and 2/3 will be transferred to the tow vehicle. One
third of this weight transfer will be carried by the front
wheels and 1/3 by the rear wheels of the tow vehicle
(See illustration). Thus, the tire load of each wheel on
the tow vehicle will be increased by 1/6 of the trailer’s
tongue weight. The tire air pressure of the tow vehicle
should be increased to compensate for this additional
weight.

[foobar]

Originally Posted by guskmg

I would ask Airstrem Service @ JC about these mods because on the longer trailers especially, frame cracking can become a problem. I would ask service just to be sure.
guskmg

Good idea. I will do that tomorrow.!

[foobar]

Originally Posted by Rickeyt

I have a 2022 Globetrotter 25FBQ and the Dexter axels are #11 capacity 3800 lbs.
The following is from the owners manual.
When a trailer is properly hitched up to a tow vehicle
with a load equalizing hitch, approximately 1/3 of the
trailer’s tongue weight will be on the trailer’s axles
and 2/3 will be transferred to the tow vehicle. One
third of this weight transfer will be carried by the front
wheels and 1/3 by the rear wheels of the tow vehicle
(See illustration). Thus, the tire load of each wheel on
the tow vehicle will be increased by 1/6 of the trailer’s
tongue weight. The tire air pressure of the tow vehicle
should be increased to compensate for this additional
weight.

Hi Rickeyt, I read that too.

Unfortunately, it’s not correct.

The amount of weight transfer is a function of the distance of the hitch ball from the rear axle of the tow vehicle and the distance of the hitch ball from the mid-point of the axle system for the trailer, etc, etc.

I ran the calculations myself and from a practical standpoint, it won’t ever end up in transferring those ratios to the tow vehicle or trailer axles.

Please read post #1 and post #61 in the link below. Post #61 specifically debunks the 1/3, 1/6th, etc etc rule of thumb ratios.

https://www.airforums.com/forums/f46...sis-19236.html

[foobar]

I remain concerned about the weight of a Globetrotter 27 FB Twin as shipped from the factory (with two A/C units) = 6674 lbs.

The GVWR is only 7600lbs so this only leaves 926 lbs for cargo.

That sounds like a lot, but a full tank of fresh water on this unit weighs 324 lbs.

Four, 300ah LiFePO4 batteries weighs 328 lbs.

As you can see, it’s pretty darn easy to chew up the remaining cargo capacity. Heck, a full set of water, grey water, and black water tanks will exceed the cargo capacity of an otherwise empty trailer. I think Airstream’s spec for GVWR is really poor on the Globetrotter 27 FB Twin.

I’m going to call Airstream tomorrow and see if there is any way to increase the GVWR (such as an axle upgrade) within the other structural limits such as the frame and trailer would have.

[foobar]

Originally Posted by foobar

I remain concerned about the weight of a Globetrotter 27 FB Twin as shipped from the factory (with two A/C units) = 6674 lbs.

The GVWR is only 7600lbs so this only leaves 926 lbs for cargo.

That sounds like a lot, but a full tank of fresh water on this unit weighs 324 lbs.

Four, 300ah LiFePO4 batteries weighs 328 lbs.

As you can see, it’s pretty darn easy to chew up the remaining cargo capacity. Heck, a full set of water, grey water, and black water tanks will exceed the cargo capacity of an otherwise empty trailer. I think Airstream’s spec for GVWR is really poor on the Globetrotter 27 FB Twin.

I’m going to call Airstream tomorrow and see if there is any way to increase the GVWR (such as an axle upgrade) within the other structural limits such as the frame and trailer would have.

Does anyone have a good contact in Jackson City for this type of engineering question?

[Life is a Highway]

With the upmost respect

Buy a real truck and a fifth wheel. Your on over load from to many YouTube stars that get it all for free although money seems to not be a problem for ya. Your first mistake is the tow vehicle

End of rant

[foobar]

Originally Posted by Life is a Highway

With the upmost respect

Buy a real truck and a fifth wheel. Your on over load from to many YouTube stars that get it all for free although money seems to not be a problem for ya. Your first mistake is the tow vehicle

End of rant

The concern expressed in the last couple of posts has nothing to do with the tow vehicle.

The concern is with the GVWR (gross vehicle weight rating) of the airstream Globetrotter 27 FB Twin vs how much the trailer weighs as delivered from the factory.

The GVWR of the trailer is 7600 lbs. The weight of the trailer as it comes from the factory is 6674 lbs.

That leaves 926 lbs for the trailer payload (GVWR - trailer weight).

That’s not enough of a payload capacity. If you simply fill all three tanks, the GVWR will be exceeded.

Or, install a modest LiFePO4 battery bank, larger inverter, solar panels, etc, and fill up the fresh water tank and you will reach 750 lbs easily. That only leaves a couple hundred lbs of payload capacity left over for food, clothes, etc.

[NY24]

Am I the only one who is wondering if the 2016 Porsche Cayenne S is ENOUGH Tow Vehicle for what you want to do. I have ZERO knowledge of said TV but, I DO know how easy it is to EXCEED one or more of the myriad of ratings RV owners need to understand and comply with (and of course a MINIMUM 10% "extra" as a safety factor; 15% would be better). I fear you're skating on VERY "thin ice".

NOTE: I just did a "quick & dirty" web check on your TV. What I'm seeing tells me my concerns are well founded.


https://duckduckgo.com/?q=2016+Porsc...romentp&ia=web

[Hans627]

Originally Posted by foobar

The concern expressed in the last couple of posts has nothing to do with the tow vehicle.

The concern is with the GVWR (gross vehicle weight rating) of the airstream Globetrotter 27 FB Twin vs how much the trailer weighs as delivered from the factory.

The GVWR of the trailer is 7600 lbs. The weight of the trailer as it comes from the factory is 6674 lbs.

That leaves 926 lbs for the trailer payload (GVWR - trailer weight).

That’s not enough of a payload capacity. If you simply fill all three tanks, the GVWR will be exceeded.

Or, install a modest LiFePO4 battery bank, larger inverter, solar panels, etc, and fill up the fresh water tank and you will reach 750 lbs easily. That only leaves a couple hundred lbs of payload capacity left over for food, clothes, etc.

I have a 2018 GT and, according to numerous CAT Scale readings, when loaded for camping including a full tank of H2O, my axle weight is about 6350# (plus or minus 50#). Your GT will weight about 200 pounds more than mine but you should have nothing to be concerned about. IMHO you are overthinking this issue.

[foobar]

Originally Posted by NY24

Am I the only one who is wondering if the 2016 Porsche Cayenne S is ENOUGH Tow Vehicle for what you want to do. I have ZERO knowledge of said TV but, I DO know how easy it is to EXCEED one or more of the myriad of ratings RV owners need to understand and comply with (and of course a MINIMUM 10% "extra" as a safety factor; 15% would be better). I fear you're skating on VERY "thin ice".

NOTE: I just did a "quick & dirty" web check on your TV. What I'm seeing tells me my concerns are well founded.


https://duckduckgo.com/?q=2016+Porsc...romentp&ia=web

Hi NY24.

By default, most folks think that we need large trucks for tow vehicles.

Reference: https://ds.aytservicecenter.com/spec...yle_id=9287252

The 2016 Cayenne S is built like a tank. Weighs 5500lbs with my wife and I in it and a full tank of fuel (I weighed it on Friday on a CAT scale). The chassis and body are extremely stiff (for performance, but is also ideal for towing). 420 HP, 406 ft-lbs of torque, available starting at 1350rpm. Massive, oversized 4 wheel disc brakes. Towing rating on the hitch is 772lbs dead weight and 1157lbs with WD hitch. Tow weight limit is artificially dictated by EU tax constraints and is limit to 3500kg (7712lbs) in order to avoid a huge tax increase if those limits are exceeded. The Cayenne is capable of towing more than the stated limits, but I'm going to try and stay within them. Please refer to the airform thread with 1600+ postings on the topic of successfully towing large airstreams with the Cayenne and it's nearly identical sisters and brothers from VW (Toureg) and Audi (the Q series ).

Contrast with the F150 as an example (not intended to start a towing war discussion, using this reference: https://www.fleet.ford.com/content/d...owingGuide.pdf)

The base F150 weighs 4000 - 5000lbs with 290HP, 265ft-lbs of torque at 4000rpm and a towing capacity of 5000lbs. To match or exceed the Cayenne's capabilities, you need a mid-range F150. Not trying to denigrate F150's here, just trying to illustrate that the Cayenne is a capable tow vehicle.

Yes, I'll be pushing the Cayenne's published limits. But, it's capable of towing more than the published limits.

Anyway, like I said above. The concern isn't with the Cayenne. My concern is with respect to the trailers limits.

I have a photo of the sticker on the side of a brand new 2022 Globetrotter 27 FB Twin with the 2nd a/c unit installed. The weight of the trailer w/2 flooded batteries and 2 full tanks of propane is 6674 lbs on the sticker (weighed before the trailer leaves the factory). The same set of stickers lists the GVWR rating for the trailer at 7600lbs. So, the payload is limited to GVWR- trailer weight = 926 lbs.

Full tank of water = 324lbs. Full tank of grey water = 332 lbs. Full tank of black water = 332 lbs.

And yes, people that boondock will refill their fresh tank using jerry cans and will sometimes have to leave the boondock location with nearly full black and grey tanks.

324 + 332 + 332 = 988lbs vs the stated 926lb remaining payload capacity.

Put a 800amp hour lithium bank onboard w/ 3000VA inverter + 700w solar and you are looking at 400lbs.

400lb solar system for boondocking + 324 lbs fresh water (and empty grey and black tanks) and you are sitting at 724lbs out of the 926lbs remaining cargo capacity.

If I run the numbers, the Globetrotter 27 FB Twin is either overweight from the factory, or is underserved by it's axles/chassis/body design limit of 7600 lbs GVWR.

What am I missing here? The numbers speak for themselves, lol.

FYI, I will probably eventually get a larger truck so I can get some additional payload capacity in the truck itself. For now, while truck availability is limited and prices are nuts, I can safely tow a GT 27 FBT with my Cayenne if I'm careful with the trailer and tongue loading. The Cayenne is quite capable.

[foobar]

Originally Posted by Hans627

I have a 2018 GT and, according to numerous CAT Scale readings, when loaded for camping including a full tank of H2O, my axle weight is about 6350# (plus or minus 50#). Your GT will weight about 200 pounds more than mine but you should have nothing to be concerned about. IMHO you are overthinking this issue.

Hans627, thanks for the data on your trailer.

Unfortunately, the 2022 GT 27's are significantly heavier when they leave the factory. Your fully loaded trailer is 6350lbs while the "empty (but with propane and batteries)" 2022 GT with dual A/C's leaves the factory at 6674lbs.

Ergo, Airstream has created a problem. I don't know where all the extra weight is coming from, maybe the new composite floor is much heavier than the plywood decking they used to use.

I'm going to be calling the airstream factory service folks later today.

[Colossus]

I appreciate all of your analysis as it’s been an interesting read. From looking at the data and having owned a 27’ TB myself I’m not a stranger to tongue weight on a 27’ AS.
I think you’ll have an issue with payload on the Porsche before you hit your limits on the trailer. I agree both numbers will be playing in the red, but from my recent experience with large battery banks, weights and Cat scales, my bets on the Porsche being over capacity before the trailer.
Here’s why, let’s say your trailers at 7000 lbs on the scale. When you connect your trailer to your Airstream, some of that trailer weight will remain on the trailer axles, but some will also be moved to the trucks drive and steer axles.
Moving this weight will make your load on your trailer axles less and increase the load on your tow vehicle axles.
I just don’t see a way around that, so IMO beefing up your trailer isn’t the answer, you’re moving the problem to your TV.
The lever in this equation is connecting the tow vehicle to the Airstream.
Either way, it’s a great read and I hope you get this sorted out to enjoy your camping experience. Good luck, I’m following.

[foobar]

Originally Posted by Colossus

I appreciate all of your analysis as it’s been an interesting read. From looking at the data and having owned a 27’ TB myself I’m not a stranger to tongue weight on a 27’ AS.
I think you’ll have an issue with payload on the Porsche before you hit your limits on the trailer. I agree both numbers will be playing in the red, but from my recent experience with large battery banks, weights and Cat scales, my bets on the Porsche being over capacity before the trailer.
Here’s why, let’s say your trailers at 7000 lbs on the scale. When you connect your trailer to your Airstream, some of that trailer weight will remain on the trailer axles, but some will also be moved to the trucks drive and steer axles.
Moving this weight will make your load on your trailer axles less and increase the load on your tow vehicle axles.
I just don’t see a way around that, so IMO beefing up your trailer isn’t the answer, you’re moving the problem to your TV.
The lever in this equation is connecting the tow vehicle to the Airstream.
Either way, it’s a great read and I hope you get this sorted out to enjoy your camping experience. Good luck, I’m following.

Thanks Colossus, I'm definitely aware of the load transfer of the tongue weight to the tow vehicle. Among other design concerns, Airstream put the center of the axle system a few inches too far towards the rear of the 27. Move it 6" or so towards the tongue and you get a much better balance in terms of where weight gets distributed across the TV and TT axles.

I have put together a load balance spreadsheet that calculates the tongue weight transfer to TV and TT axles. I am enhancing it so that I can also use it to control the tongue weight when planning for my desired trailer upgrades and for determining where I need to place the loads in my trailers when I add our personal gear. Sure, I can just buy a massive pickup truck so that nothing I do in the trailer will impact the tow vehicle, but where is the fun in that for a retired electrical engineer with too much time on his hands!!

For example, if I place a 328 lb 1200ah battery bank in the middle rear of the trailer inside a new settee that will span the rear of the 27 FBT, it will reduce the tongue weight by 131 lbs while adding 328lbs towards the trailer GVWR. If I eliminate the two 100.6 lb flooded group 27 interstate brand batteries from the A-frame battery compartment located 33 inches aft of the coupler, I will reduce the tongue weight by 85lbs.

So, I will definitely have to manage tongue weight in order to avoid overloading the Cayenne in terms of max payload and also the TV rear axle GAWR. However, my biggest problem in the short term is the relative lack of payload capacity on the 2022 GT 27 FBT after whatever Airstream did to add so much mass to the trailer. The GVWR problem with respect to the trailer is independent of the tow vehicle concerns. I'd like to upgrade the trailer's GVWR if possible (axles with higher GAWR?) to gain some cargo capacity and some safety margin to the trailer limits. I will still want to keep the trailer as light as possible and manage the tongue weight so I can safely tow with the Cayenne in the near term. Eventually, I will get a larger, more capable tow vehicle. For now, I'm enjoying the challenge of making this work in the short term

[WellSaid11]

You will be fine on the weight for the axles on the GT.

I had both a Cayenne S and a Q7 TDI.

That trailer will likely wag your Cayenne all over the place much of the time you are towing unless there is no wind, no semis on the road and the road is completely flat.

If you plan on towing a whole lot with the Cayenne you will need to get a second and third job to pay for the wear and tear on your rig from towing and hard miles.

You should get a different tow vehicle.

[foobar]

Originally Posted by WellSaid11

You will be fine on the weight for the axles on the GT.

I had both a Cayenne S and a Q7 TDI.

That trailer will likely wag your Cayenne all over the place much of the time you are towing unless there is no wind, no semis on the road and the road is completely flat.

If you plan on towing a whole lot with the Cayenne you will need to get a second and third job to pay for the wear and tear on your rig from towing and hard miles.

You should get a different tow vehicle.

Points well taken WellSaid11. I do plan to eventually get a bigger tow vehicle with more payload and towing capacity. However, for the first couple of years of towing, I don't expect to put more than 4-5K miles per year of towing wear and tear on the Cayenne. I'm not anticipating anything catastrophic happening to the Cayenne in that period of time. But, I have some $$ set aside for that purpose if needed.

If towing turns into a constant white knuckle exercise, the first response will be to slow down. Sway effects increase with the cube of the windspeed so slowing down will help dramatically. If that's not enough or results in intolerably slow speed, I'll change my plans with respect to the tow vehicle.

Note that F150 half ton trucks are 4000-5000 lbs and the Cayenne is just under 5000lbs. Other than a shorter wheelbase, the Cayenne isn't going to much different than a half ton F150 in terms of behavior when towing. And yes, I'm sure lots of folks would rather tow with a semitractor trailer rig or an F350/F250 class of tow vehicle. But it's really not necessary.