Ok, I am going to collect random thoughts and progress pictures and put them here in a thread.
Goal: Construct a true flatbed camper with cabover, no slideouts but full 8 foot floor width inside. This will mount on a 2006 Isuzu NRR truck with a GVWR of 19,500 pounds and a current dry weight of 8700 pounds. The truck has a 20 foot flatbed that is 8 feet wide. The camper will take up 11 feet of the flatbed and the remaining area will be home to a future garage for our toys. We will install a hitch so we can pull our 17 foot Montgomery sailboat (trailer + boat is about 2200 pounds). The camper and garage will be removeable so the flatbed can be used for other purposes, or in case the truck needs extensive shop repairs down the road. Or if we are in Alaska and want to go pick up 3 cords of firewood or something 🙂
Here is a picture of the truck with some important dimensions:
Goal: Construct a true flatbed camper with cabover, no slideouts but full 8 foot floor width inside. This will mount on a 2006 Isuzu NRR truck with a GVWR of 19,500 pounds and a current dry weight of 8700 pounds. The truck has a 20 foot flatbed that is 8 feet wide. The camper will take up 11 feet of the flatbed and the remaining area will be home to a future garage for our toys. We will install a hitch so we can pull our 17 foot Montgomery sailboat (trailer + boat is about 2200 pounds). The camper and garage will be removeable so the flatbed can be used for other purposes, or in case the truck needs extensive shop repairs down the road. Or if we are in Alaska and want to go pick up 3 cords of firewood or something 🙂
Here is a picture of the truck with some important dimensions:
BoonHauler: Yes, that is a Atwood 7920-II 18,000 BTU input furnace. Good eye!
A little side project here. I was planning to make some outdoor floodlights for our camper. I wanted very bright, low profile, LED lights with adjustable intensity. Hard to find cheap so I was going to make my own.
While at Camping World this past weekend, I saw these incandescent porch lights for $9.95. I didn't care about the guts but the housing and lens looked about perfect (and very hard for me to make myself). I purchased some and yesterday converted them into (insanely) bright outdoor floods for our camper. For the LED elements I used the modules out of failed 450 lumen 7.5 watt household style 60 watt bulbs. It turns out the electronics in this model fail after a short while because of poor quality but the LED elements are perfectly fine. The LED elements are mounted to a aluminum backed circuit board and quite robust.
The LED series string runs on about 36V DC at 250mA so I used a little potted DC-DC current regulated converter to drive two of them in parallel (this particular model is a 700mA Flexblock by LuxDrive). The current (and thus light output) is controlled by a simple resistor (or potentiometer for variable light intensity).
I cut a little 1/8" thick aluminum plate to mount the flat LED modules then bent a 1/16" thick aluminum bracket to hold this plate at angle. LEDs do generate some heat but it is likely some of that will flow through the aluminum bracket into the aluminum skin of our RV. At any rate, it is a lot better heat dissipation than the little LED incandescent replacement bulbs you see in stores.
The last photo shows it running at about 80% of full power. It is saturating the camera and my eyes still are a bit sore from looking at it from 12 feet away. One side of the camper will have two of these :E Don't camp too close to me if you want to sleep!
A little side project here. I was planning to make some outdoor floodlights for our camper. I wanted very bright, low profile, LED lights with adjustable intensity. Hard to find cheap so I was going to make my own.
While at Camping World this past weekend, I saw these incandescent porch lights for $9.95. I didn't care about the guts but the housing and lens looked about perfect (and very hard for me to make myself). I purchased some and yesterday converted them into (insanely) bright outdoor floods for our camper. For the LED elements I used the modules out of failed 450 lumen 7.5 watt household style 60 watt bulbs. It turns out the electronics in this model fail after a short while because of poor quality but the LED elements are perfectly fine. The LED elements are mounted to a aluminum backed circuit board and quite robust.
The LED series string runs on about 36V DC at 250mA so I used a little potted DC-DC current regulated converter to drive two of them in parallel (this particular model is a 700mA Flexblock by LuxDrive). The current (and thus light output) is controlled by a simple resistor (or potentiometer for variable light intensity).
I cut a little 1/8" thick aluminum plate to mount the flat LED modules then bent a 1/16" thick aluminum bracket to hold this plate at angle. LEDs do generate some heat but it is likely some of that will flow through the aluminum bracket into the aluminum skin of our RV. At any rate, it is a lot better heat dissipation than the little LED incandescent replacement bulbs you see in stores.
The last photo shows it running at about 80% of full power. It is saturating the camera and my eyes still are a bit sore from looking at it from 12 feet away. One side of the camper will have two of these :E Don't camp too close to me if you want to sleep!
Long time with no update. We have been working a bit here and there getting the systems installed and interior layout.
As mentioned we went with a 12V/24V NovaKool compressor fridge instead of the 3-way propane fridge we had already purchased (oops). The NovaKool vents to the front so I had to seal up the huge holes I had cut in the side for the previous fridge. I will have to either put a fake screen over the aluminum or some big stickers 😉
For the kitchen counter, we went back and forth about what to do. At first I was going to go cheap and get the quick and dirty veneer covered particle board counter you find at Lowes/Depot. We then started thinking about Corian. While visiting Crosscut Hardwoods, we saw some solid walnut 1.5" thick countertops and were sold. I mean, how many truck campers have a solid walnut countertop? :C
The backsplash is made up of metal tiles although it has not been finished and will wrap around to the stove.
The stove, water heater, and furnace are all installed and working on propane. I made a sealed metal box for the propane fittings that is vented to the outside. It also contains a solenoid valve controlled by a propane leak sensor which will shut off the propane automatically in event of a leak. I pressure tested the system for a week with a manometer and it held perfect pressure.
The wiring panels are Blue Sea marine versions that you find in boats (exact DC model is in our sailboat). They are very nice quality and I just like the look and feel. It was a mass of wiring but I tried to route it neatly. I used a CO2 laser attached to the head of my cnc mill to cut out the protection acrylic for the AC section. I will miss that tool when we hit the road...
We made a shroud with ducting for the little AC window unit that allows it to reside totally inside the RV. There is a pan that can drain to the outside and everything is aluminum and weatherproofed around the AC unit. It seems to work quite well although the hottest day we have had was 82 (it cooled down to 68 very fast). Obviously we will not use it a lot because even at 600 watts it is too much for a battery bank.
We also finally got the door and windows installed. The camper is getting very close to being weatherproofed. I need to install the clearance lights and flood lights plus seal up a few hatches. I am itching to see this thing on the truck but I know it will be a lot harder to work on it out in the driveway vs in the garage. Still, I think we will have a picture of it on the truck this summer. We will finish up cabinets and flooring this fall/winter.
As mentioned we went with a 12V/24V NovaKool compressor fridge instead of the 3-way propane fridge we had already purchased (oops). The NovaKool vents to the front so I had to seal up the huge holes I had cut in the side for the previous fridge. I will have to either put a fake screen over the aluminum or some big stickers 😉
For the kitchen counter, we went back and forth about what to do. At first I was going to go cheap and get the quick and dirty veneer covered particle board counter you find at Lowes/Depot. We then started thinking about Corian. While visiting Crosscut Hardwoods, we saw some solid walnut 1.5" thick countertops and were sold. I mean, how many truck campers have a solid walnut countertop? :C
The backsplash is made up of metal tiles although it has not been finished and will wrap around to the stove.
The stove, water heater, and furnace are all installed and working on propane. I made a sealed metal box for the propane fittings that is vented to the outside. It also contains a solenoid valve controlled by a propane leak sensor which will shut off the propane automatically in event of a leak. I pressure tested the system for a week with a manometer and it held perfect pressure.
The wiring panels are Blue Sea marine versions that you find in boats (exact DC model is in our sailboat). They are very nice quality and I just like the look and feel. It was a mass of wiring but I tried to route it neatly. I used a CO2 laser attached to the head of my cnc mill to cut out the protection acrylic for the AC section. I will miss that tool when we hit the road...
We made a shroud with ducting for the little AC window unit that allows it to reside totally inside the RV. There is a pan that can drain to the outside and everything is aluminum and weatherproofed around the AC unit. It seems to work quite well although the hottest day we have had was 82 (it cooled down to 68 very fast). Obviously we will not use it a lot because even at 600 watts it is too much for a battery bank.
We also finally got the door and windows installed. The camper is getting very close to being weatherproofed. I need to install the clearance lights and flood lights plus seal up a few hatches. I am itching to see this thing on the truck but I know it will be a lot harder to work on it out in the driveway vs in the garage. Still, I think we will have a picture of it on the truck this summer. We will finish up cabinets and flooring this fall/winter.
While thinking about the solar panel mounts I started to have some concern/curiosity about the vertical CoG of the combined truck/camper (yes I realize this could have been analyzed earlier). I have downloaded the body builder's manual for the 2006 Isuzu N series and located the correct pages relating to CoG. I am not concerned right now with horizontal CoG but rather vertical CoG as it would affect sway and possible rollover.
The first inclination is "eh, it will be alright" but that is not how I roll. So...
*Danger* Math Ahead, Proceed With Caution
The important number is the VCg or total average vertical center of gravity of the complete truck/camper. To calculate this you use the formula:
VCg = (Mv + Mb + Mp + Me) / (Wv + Wb + Wp + We)
Where Mv is the moment of vehicle, Wv is the weight of vehicle, Mb is the moment of body (flatbed in our case), Wb is the weight of the flatbed, Mp is the moment of payload (camper), Wp is the weight of the camper, Me is the moment of equipment (we will call it solar panels/frame for this), and We is the weight of equipment.
With me so far? Amazing. Shouldn't we be discussing dry rot or something by now? Anyway, continuing...
From the body builder's guide, our Isuzu NRR with 176" WB has a vehicle weight of 6184 pounds and the distance from the ground to the vertical CoG of the vehicle itself is 18.9" (the 176" WB has the lowest CoG, so that is nice)
We can then calculate the moment of the vehicle Mv = 6184 x 18.9 = 116878 lbs-in
For the weight of the flatbed, we know the last time we went over the scales the truck weighed in at 8700 pounds. Since the bare truck is 6184 pounds, the flatbed must weigh about 2516 pounds. The distance from the ground to the top of the flatbed is 41" and if we use this as the distance to vertical CoG it should be a very conservative guess even though the headache rack is much taller. Most of the mass is actually below the 41".
We can now calculate the moment of the flatbed Mb = 2516 x 41 = 103156 lbs-in
The combined VCg for just the truck and flatbed is
(116878 + 103156) / (8700) = 25.29 inches
So far so good. The body builder guide says the max VCg for the entire vehicle/body/payload should not exceed 63 inches. At least now we know the empty truck and flatbed shouldn't tip over 🙂
Now the hard part. I have NFC what the weight or vertical CoG distance is for the camper. I can't load it up on the truck yet and drive to the scales, plus we have not installed the batteries, inverter, sofa, cabinets, etc.
What I can do is figure out what the maximum camper weight and vertical distribution can be to still keep the vertical CoG under 63" for the entire truck/camper. I will still have to make some assumptions but at least it will be something to keep in mind until I can figure out a way of better estimating the actual weight and distribution.
Assume we keep most of the mass in the camper low, we might expect the vertical CoG to at least be less than half the height of the camper. Our camper is 8 feet tall, so we will plug in 48" + 41" = 89" for the vertical distance to CoG. This now leaves just one variable Wp which is the max weight the camper can be at that 89" vertical CoG distance for the entire unit vertical CoG distance to stay under 63".
So we have the formula:
63 = (116878 + 103156 + Wp*89) / (8700 + Wp)
(Sorry for the aneurysm but you were getting on in years anyway.)
Solving for Wp we get Wp = 12618 pounds
Wow, is that right? So if we keep the camper CoG at least distributed so the vertical distance from the ground to the camper CoG is no more than 89" we can have a 12,000 pound camper?!?
Lets double check those numbers by plugging 12,618 and 89" into the VCg formula:
Mp = 12,618 x 89 = 1123002 lbs-in
VCg = (Mv + Mb + Mp) / (Wv + Wb + Wp)
VCg = (116878 + 103156 + 1123002) / (8700 + 12618)
VCg = 63 inches
Relief. Since I know our camper is nowhere near 12,000 pounds and I believe the mass will be distributed more in the lower section, I think we can proceed with our solar panel mount on the roof even if it ends up being several hundred pounds at 12 feet high.
(hello to my wife, the only one who could have possibly read this far)
The first inclination is "eh, it will be alright" but that is not how I roll. So...
*Danger* Math Ahead, Proceed With Caution
The important number is the VCg or total average vertical center of gravity of the complete truck/camper. To calculate this you use the formula:
VCg = (Mv + Mb + Mp + Me) / (Wv + Wb + Wp + We)
Where Mv is the moment of vehicle, Wv is the weight of vehicle, Mb is the moment of body (flatbed in our case), Wb is the weight of the flatbed, Mp is the moment of payload (camper), Wp is the weight of the camper, Me is the moment of equipment (we will call it solar panels/frame for this), and We is the weight of equipment.
With me so far? Amazing. Shouldn't we be discussing dry rot or something by now? Anyway, continuing...
From the body builder's guide, our Isuzu NRR with 176" WB has a vehicle weight of 6184 pounds and the distance from the ground to the vertical CoG of the vehicle itself is 18.9" (the 176" WB has the lowest CoG, so that is nice)
We can then calculate the moment of the vehicle Mv = 6184 x 18.9 = 116878 lbs-in
For the weight of the flatbed, we know the last time we went over the scales the truck weighed in at 8700 pounds. Since the bare truck is 6184 pounds, the flatbed must weigh about 2516 pounds. The distance from the ground to the top of the flatbed is 41" and if we use this as the distance to vertical CoG it should be a very conservative guess even though the headache rack is much taller. Most of the mass is actually below the 41".
We can now calculate the moment of the flatbed Mb = 2516 x 41 = 103156 lbs-in
The combined VCg for just the truck and flatbed is
(116878 + 103156) / (8700) = 25.29 inches
So far so good. The body builder guide says the max VCg for the entire vehicle/body/payload should not exceed 63 inches. At least now we know the empty truck and flatbed shouldn't tip over 🙂
Now the hard part. I have NFC what the weight or vertical CoG distance is for the camper. I can't load it up on the truck yet and drive to the scales, plus we have not installed the batteries, inverter, sofa, cabinets, etc.
What I can do is figure out what the maximum camper weight and vertical distribution can be to still keep the vertical CoG under 63" for the entire truck/camper. I will still have to make some assumptions but at least it will be something to keep in mind until I can figure out a way of better estimating the actual weight and distribution.
Assume we keep most of the mass in the camper low, we might expect the vertical CoG to at least be less than half the height of the camper. Our camper is 8 feet tall, so we will plug in 48" + 41" = 89" for the vertical distance to CoG. This now leaves just one variable Wp which is the max weight the camper can be at that 89" vertical CoG distance for the entire unit vertical CoG distance to stay under 63".
So we have the formula:
63 = (116878 + 103156 + Wp*89) / (8700 + Wp)
(Sorry for the aneurysm but you were getting on in years anyway.)
Solving for Wp we get Wp = 12618 pounds
Wow, is that right? So if we keep the camper CoG at least distributed so the vertical distance from the ground to the camper CoG is no more than 89" we can have a 12,000 pound camper?!?
Lets double check those numbers by plugging 12,618 and 89" into the VCg formula:
Mp = 12,618 x 89 = 1123002 lbs-in
VCg = (Mv + Mb + Mp) / (Wv + Wb + Wp)
VCg = (116878 + 103156 + 1123002) / (8700 + 12618)
VCg = 63 inches
Relief. Since I know our camper is nowhere near 12,000 pounds and I believe the mass will be distributed more in the lower section, I think we can proceed with our solar panel mount on the roof even if it ends up being several hundred pounds at 12 feet high.
(hello to my wife, the only one who could have possibly read this far)
