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orbywan 07-13-2011 08:01 PM

Aero RV (custom boat tail for '95 Ford E-350 Class C motorhome)
 
10 Attachment(s)
About a month ago I decided to build a boat tail for my 95 E-350 Ford 25 foot turbo diesel Class C motor home. I read the aerodynamics study NASA did at Dryden Air Force base back in the late 60ís on the squared off E-150 van about 20 times, as well as several other studies, drew up some plans and three weeks later and some serious sweat the prototype is done and tested.
Photos of the process are posted below. I used ĹĒ square tubing for the ribs. I determined the shape I wanted, hammered out a Ďcontrolí rib, taped it to the bench and then built 28 more just like it, so the four sides have the same shape coming inward. Next I built the rear frame, then made it bigger, then added ribs one at a time until I had the shape.
The basic frame weighs about 75 pounds, which is about 25 pounds heavier than the rear bumper that was removed, so there is a net gain of about 25 pounds plus the weight of 5 sheets of coroplast, and a bunch of aluminum pop rivets.
I tried my best to replicate the rounded corners of the body on this vehicle because it makes sense to me that going from a rounded corner right to a 90 degree square corner wouldnít be conductive to smooth air flow.
This creates lots of compound curves, which are a pain to cover, but as far as the prototype skin is concerned it wasnít too bad. The four corners were the worst so I used monocoat to cover them, which is heat shrink plastic made for covering model airplane wings and fuselages, available at most hobby stores. The larger areas are covered in coroplast. You can see in the photos where the panels had to be cut and trimmed to allow for the compound curves. Not much modification considering the shape.
In an attempt to keep the air flow over the roof area good, I also faired the roof A/C housing. According to the tell tales, that worked out really well, although now that I know the overall fairing design is good, now I have to get the A/C to work with the fairing in place. I think maybe if I louver the hell out of the final cover it will be good.
Iíve only done one road test of the new design so far but it was very encouraging. Getting up at 3AM to beat the heat and wind, we (my wife insisted on going, she thinks the boat tail is great, how cool is that?) drove from Tucson to Phoenix, which is about 1,000 feet lower elevation, to Apache Junction, a total distance of 135+ miles, one way, with lots of subtle hills and valleys in between. We didnít use the A/C and we ran right at 57-58mph, since that is the Ďsweet spotí for this drive line (7.3L turbo diesel Ford, A4OD auto trans, 4.10 tail gear).
The drive up yielded 17.26 mpg, compared to an average of 13.1 for the same trip sans the boat tail. I have to say by the time the tail was completed I was having my doubts this would make much of a difference so I was really happy with that. The return trip we used the A/C the whole way, and had an intermittent crosswind of about 10 to 20 mph and got 14.68mpg. That works out to a two way average of 15.97mpg. Not bad for a first try under those conditions.
Anyway, it will take a lot more testing to know the accurate numbers of course but Iím very happy with the initial results. I also have a ton more work to do before this is anywhere near ideal or finished. I still have to skin the rest of the under carriage. For this test, about the last 3 feet of the belly pan was installed and Iím guessing it was catching some air in there. So far the cost of this extravaganza is about $225 for materials, which was way worth it just for entertainment value, for me as well as my friends. If I had 5 bucks for every time someone has said, ĎWhat the HELL is that?í, the materials would be paid for. : )

skyl4rk 07-13-2011 08:12 PM

Very nice job, professional.

skyking 07-13-2011 09:06 PM

nice job man. This is another inspiration!
How about some other pics of the rig, it looks pretty slick.
I've been looking at mini split heat pumps as a replacement for failed AC units. It would get them off the roof, you could hang them on the back of the rig. They are also a great deal more efficient.

jime57 07-13-2011 09:24 PM

Great job! Wish I had you here in Richmond to work on my diesel pusher.

I think you might be a bit unfair to yourself with your math. If your baseline was without A/C, then that is the only data that really counts. But I certainly know how difficult it is to get good data. Initially, I think it looks very encouraging.

orbywan 07-13-2011 09:27 PM

Aero RV
 
10 Attachment(s)
Here are some more photos of the process. I wasn't aware they made heat pumps for RV's, Skyking, do you have any info on that? I'd love to get that big pile off the roof. Thanks.

skyking 07-13-2011 10:57 PM

Mini Split Air Conditioner AmericAire 120000 Heat Pump

They are not specifically designed for RV's but a quick search and you will find plenty of folks "down under" who have retrofitted them on Rvs with great success. They have extreme heat and also extreme rough road conditions in Australia, so I consider that a good testament to the durability.
What gets me going is the lower power draw of the 12,000 BTU units. It is 2/3rds of the rated draw of a typical Coleman 13,500 BTU unit. I suspect that a Honda EU2000i generator just *might* be able to start it.
The other huge bonus is when you are plugged into a full hookup situation. Now you have a 12,000 BTU heat pump, also much more efficient. Keep that propane in your tank.

In your case you would hang the outdoor unit on the back, find a suitable wall and route the line set and cables, and finish off with an Rv skylight to fix the hole where the old AC was.
RV Skylight

Frank Lee 07-13-2011 11:08 PM

Looks good; very inspirational!

One question: is the flow any good along the bottom? Seems too much rise down there for attached flow... Looks like the tufts are swirling around in pic 7.

larrybuck 07-13-2011 11:53 PM

Congrats on a great start! Perhaps full side skirts soon?

orbywan 07-14-2011 01:23 AM

Quote:

Originally Posted by Frank Lee (Post 250206)
Looks good; very inspirational!

One question: is the flow any good along the bottom? Seems too much rise down there for attached flow... Looks like the tufts are swirling around in pic 7.

I'm hoping that completing the belly pan will help help the flow down there because it's not very good. I may have to straighten the curve at the bottom some. So far it's only skinned about 3 feet forward from the rear. That could be effecting the flow in itself.

orbywan 07-14-2011 01:31 AM

Quote:

Originally Posted by larrybuck (Post 250220)
Congrats on a great start! Perhaps full side skirts soon?

OK, I'm new at this, what is a full side skirt? If you're talking about something kind of like a side air dam, I hadn't considered it because we take this vehicle off road a fair amount. The plan is to skin the rest of the undercarriage and fair both duallies and see how that does.

Maybe full skirts would work if they were pretty flexible. If I skin the undercarriage should I also put a front air dam on it, or is that redundant?

orbywan 07-14-2011 01:34 AM

Quote:

Originally Posted by Frank Lee (Post 250206)
Looks good; very inspirational!

One question: is the flow any good along the bottom? Seems too much rise down there for attached flow... Looks like the tufts are swirling around in pic 7.

Frank, to be honest, I'm surprised the air flows as well as it does on the top and the sides, I was very concerned that I pulled them in too far. So far the results say it's pretty good but the testing is too incomplete to say for sure.

orbywan 07-14-2011 01:36 AM

Quote:

Originally Posted by skyking (Post 250203)
Mini Split Air Conditioner AmericAire 120000 Heat Pump

They are not specifically designed for RV's but a quick search and you will find plenty of folks "down under" who have retrofitted them on Rvs with great success. They have extreme heat and also extreme rough road conditions in Australia, so I consider that a good testament to the durability.
What gets me going is the lower power draw of the 12,000 BTU units. It is 2/3rds of the rated draw of a typical Coleman 13,500 BTU unit. I suspect that a Honda EU2000i generator just *might* be able to start it.
The other huge bonus is when you are plugged into a full hookup situation. Now you have a 12,000 BTU heat pump, also much more efficient. Keep that propane in your tank.

In your case you would hang the outdoor unit on the back, find a suitable wall and route the line set and cables, and finish off with an Rv skylight to fix the hole where the old AC was.
RV Skylight

Thanks Skyking, I'll definetly check it out.

ChazInMT 07-14-2011 03:30 AM

The build quality of your Kamm Extension is very good, I hate to sound critical, but I believe you have made the taper too "fast". I'm sure it helps, and as we can see from your tuft tests, flow remains attached, however, if you didn't pull it in quite so much, I suspect it would work even better.

The Kamm should maybe be less tapered like the back of this camper concept.

http://i51.tinypic.com/10mkjrq.jpg

I know it seems counterintuitive that making the back end bigger could be better than the smallish back you have created, but it has to do with keeping the shape of the vehicle close to the Aero Template. Also notice how the taper on my concept camper drawing starts very gradually, the rate of change on the shape is slow. You wanna always try and not make abrupt changes in the air flow on the back end of a vehicle.

As far as the AC fairing goes, I think if you just cut off the back foot of it for air flow, it will make very little difference in the Cd improvement you have made by making it a full fairing. It will still work very well to reduce drag, and it looks very well designed, cutting the back off will allow it to operate as an AC unit without having to futz with it or make up some sort of louver thing.

http://i56.tinypic.com/netkz8.jpg


I only mention all this cause it sounds as if you project is a sort of prototype and you may make another version 2 of the same thing, I'd hope you consider making the Kamm shape less aggressive if you do.

Again, Excellent Job!!

t vago 07-14-2011 09:46 AM

Quote:

Originally Posted by ChazInMT (Post 250241)
I only mention all this cause it sounds as if you project is a sort of prototype and you may make another version 2 of the same thing, I'd hope you consider making the Kamm shape less aggressive if you do.

I second that observation. You did make your taper too aggressive. I offer my own experiences to show.

http://www.tom-viki.com/spgm/gal/Car...1010200002.jpg

Version 1 of my aerocap, as you can see above, had a pretty aggressive slope. With it, I saw an average of 3.6% improvement in FE.

http://www.tom-viki.com/spgm/gal/Car...1106210003.jpg

Version 2 above, as you can see, is nowhere near as aggressive. While version 1 tapered down to about 2 inches at the back, version 2 tapers down to about 11 inches. Also notice the nice big 8 inch gap between the aerocap and the cab rear. Common sense would tell you that these things I pointed out would not work so well.

The incomplete form of version 2 netted me a 6% improvement in FE.

http://www.tom-viki.com/spgm/gal/Car...1107120000.jpg

The complete form of version 2, with the 8 inch gap filled in, netted a 10% improvement over no cap.

Now, it's not to say that you did a bad job. One can't ignore an 18% improvement in FE like you saw with your camper extension here.

However, should you build a version 2 for some reason (I built my version 2 because my version 1 decided to fly away from my truck at speed and destroy itself), you should keep in mind our advice to build a less aggressively sloped version.

Quote:

Originally Posted by ChazInMT (Post 250241)
Again, Excellent Job!!

I second that, too.

orbywan 07-14-2011 10:55 AM

T vago and Chas,
Like I told Frank above, I was very concerned that I pulled the shape in too tight, but didnít realize it until I was so far into it I decided to try it as is. The top flow seems to be excellent according to the tales, the sides are OK and the bottom is crap. Since itís already built and since it will be a major job to reshape it, Iím going to finish the belly pan and fair the duallies and see if that improves the bottom flow, then do some more testing and see what it yields.
If the maiden voyage results turn out to be fairly accurate (too early to tell at this point) and the other improvements add significantly to those numbers, I may leave it alone and defer to the Ďif it works donít fix ití axiom, but weíll see.
T vago your bed fairing is excellent, nice workmanship on the curves and angles. Have you considered a hitch mounted boat tail for the rest of the rear end? Easy in, easy out. I'm going to build one for my Tundra as soon as I have time. You know, in my spare time. Ha.
Thanks for the input on the A/C fairing, Chas, Iím not sure what to do with that yet, I may just might take it off since we use it so seldom.
Does anyone know the best way to get, build or buy something that will calculate mpg from an OBD I vehicle like my 95 RV?

wyatt 07-14-2011 01:16 PM

Quote:

Originally Posted by orbywan (Post 250286)
Does anyone know the best way to get, build or buy something that will calculate mpg from an OBD I vehicle like my 95 RV?

I don't know if the MPGuino will work with a diesel (it never used to), but I know there was talk of it once... you may want to ping DCB with a PM to see what he knows.

As to your comment about $5 for every time someone asked what it was paying for materials... you would be way in the clear if you include all the people in their cars asking the same thing!

I am with others. If there happens to be a v2.0 you should stick with a 15 degree maximum slope. On the other hand, it is awfully hard to argue with the improvement you saw...

orbywan 07-14-2011 01:33 PM

Quote:

Originally Posted by wyatt (Post 250313)
I don't know if the MPGuino will work with a diesel (it never used to), but I know there was talk of it once... you may want to ping DCB with a PM to see what he knows.

As to your comment about $5 for every time someone asked what it was paying for materials... you would be way in the clear if you include all the people in their cars asking the same thing!

I am with others. If there happens to be a v2.0 you should stick with a 15 degree maximum slope. On the other hand, it is awfully hard to argue with the improvement you saw...

Thanks for the info, I'll see if I can find DCB. Yes, we had some serious rubber necking going on the first road test, it was pretty funny. If I do the shape over I'll back off the slope a bit, it looks too steep to me also.

ecofreak 07-14-2011 02:06 PM

By far, the MPGuino is the most easily tailored and available MPG monitor in existence. Here's the OBDuino variant thread, which should at least have some merit or inspiration for you.

Also, great work on the boat-tail! The taper, sure, might be a bit sharp, but for what I know, as long as your bottom taper is less than 15 degrees, you're in the zone. Motorhomes, especially Class A, have always put me off for many reasons (I'm a bit too fond of tents and bicycle touring!), but I appreciate your efforts in ecomodding one.

orbywan 07-14-2011 02:30 PM

Quote:

Originally Posted by ecofreak (Post 250323)
By far, the MPGuino is the most easily tailored and available MPG monitor in existence. Here's the OBDuino variant thread, which should at least have some merit or inspiration for you.

Also, great work on the boat-tail! The taper, sure, might be a bit sharp, but for what I know, as long as your bottom taper is less than 15 degrees, you're in the zone. Motorhomes, especially Class A, have always put me off for many reasons (I'm a bit too fond of tents and bicycle touring!), but I appreciate your efforts in ecomodding one.

Thanks for the Guino link, I'll check it out. It's quite likely I'll have to lower the bottom.
"Motorhomes, especially Class A, have always put me off for many reasons (I'm a bit too fond of tents and bicycle touring!), but I appreciate your efforts in ecomodding one.[/QUOTE][/I]"
I know what you mean, I traveled lighter until I started getting older. After that, beat to hell syndrome started sneaking up, I want some walls around me and some comfort. Yeah, I know, wussie.:cool:

Cd 07-14-2011 05:47 PM

Wow ! That - is - beautiful, especially that A/C fairing.
Bravo.
I agree with everyone else about the angles being too steep on the main 'tail, but on a positive note, you have filled in a HUGE amount of your wake with this mod !

As far as the A/C unit, why not have your cake and eat it too ? Just keep the length and add louvers to it as you mentioned. ( I must admit that I like to look of it though and would hate to see you have to cut on it ) You could also use screen or a fire resistant cloth material which would allow the unit to breathe but keep the full shape.

JasonG 07-15-2011 06:12 PM

Awesome !
Never thought of fairing my AC units. Cool.

The belly pan on the fiver netted around 1MPG for me. (That's nearly 3%)
The biggest benefit is (so it seems) is less sway in cross winds. I'm guessing from the wind pushing on the I beams.

I have to figure a way to make a Kamm clear the ramp door though..........

Can't wait to see V2 !!

orbywan 07-15-2011 07:06 PM

Quote:

Originally Posted by JasonG (Post 250487)
Awesome !
Never thought of fairing my AC units. Cool.

The belly pan on the fiver netted around 1MPG for me. (That's nearly 3%)
The biggest benefit is (so it seems) is less sway in cross winds. I'm guessing from the wind pushing on the I beams.

I have to figure a way to make a Kamm clear the ramp door though..........

Can't wait to see V2 !!

I should have tested it before and after with the A/C fairing but according to the tell tails the air is flowing perfectly over the rear upper section, in spite of the steep angle. I think the A/C fairing is mostly responsible for that.

If you can figure out a way to Kamm the back, I'd love to see the results mileage-wise. I've never seen it done on a 5th wheel before. Never saw it done on an RV before either. To be honest I didn't think it would make such a big difference, but I kept looking at the huge abrupt drop off (for the air) area at the back and figured if it worked for NASA (referring to the Dryden AFB tests), I'll give it a shot. Completing the belly pan is next.

aerohead 07-16-2011 02:47 PM

RV-Kamm
 
Quote:

Originally Posted by orbywan (Post 250499)
I should have tested it before and after with the A/C fairing but according to the tell tails the air is flowing perfectly over the rear upper section, in spite of the steep angle. I think the A/C fairing is mostly responsible for that.

If you can figure out a way to Kamm the back, I'd love to see the results mileage-wise. I've never seen it done on a 5th wheel before. Never saw it done on an RV before either. To be honest I didn't think it would make such a big difference, but I kept looking at the huge abrupt drop off (for the air) area at the back and figured if it worked for NASA (referring to the Dryden AFB tests), I'll give it a shot. Completing the belly pan is next.

I don't know if a 1970 VW Westfalia Campmobile qualifies as an RV,but the 18-inch boat tail,with Breer/Fachsenfeld/Kamm-chop that I put on it in 1980 was good for almost 4 mpg by itself.
The radiused tail of the VW allowed more lead in curvature,so in essence,the virtual boat tail was more like 2-feet in length.
The tail curved into a maximum 20-degree angle,top and sides.No bottom.
With spare tire cover( on nose),full bellypan,rear wheel skirts,and tail,the van was capable of as high as 35 mpg @ 55 mph,up from 27 mpg.

orbywan 07-16-2011 06:29 PM

Quote:

Originally Posted by aerohead (Post 250607)
I don't know if a 1970 VW Westfalia Campmobile qualifies as an RV,but the 18-inch boat tail,with Breer/Fachsenfeld/Kamm-chop that I put on it in 1980 was good for almost 4 mpg by itself.
The radiused tail of the VW allowed more lead in curvature,so in essence,the virtual boat tail was more like 2-feet in length.
The tail curved into a maximum 20-degree angle,top and sides.No bottom.
With spare tire cover( on nose),full bellypan,rear wheel skirts,and tail,the van was capable of as high as 35 mpg @ 55 mph,up from 27 mpg.

I didn't mean it's never been done before, I've just never seen one on an RV, except in PhotoShop. An 18" boat tail seems really short, but it was a short vehicle, goes to show how much they make a difference I guess.

Doing a belly pan on this RV is going to be a pain but I kind of have to finish it. If I put a full pan on it, should I also make a front air damn?

shorttimer 07-17-2011 01:49 AM

Super pro work! If you do as good of a job for an under belly, I'll bet you pick up another nice 'reward'. Keep it up!

bondo 07-17-2011 09:02 AM

That is some very impressive work. Enjoy the extra money you will save that you don't spend on fuel.

Bondo

slowmover 07-17-2011 04:43 PM

I have to get the A/C to work with the fairing in place.

I admire this. Have been saving pics of aircraft wheel fairings and turbine engine air inlets to someday streamline a roof A/C on an aluminum trailer (looks & performance).

cleanspeed1 07-17-2011 05:19 PM

Excellent job on the aeromods! You should give Jody a call at dpTuner for an economy tune since you have a PSD. Will still pick up a little power, optimize the shift points in the transmission. If you haven't done the exhaust yet, Hypermax has a good system with a downpipe ( the stock downpipe is crushed from the factory to fit the chassis ) that doesn't cost an arm and a leg. And switch to Evans Coolant.

thatguitarguy 07-18-2011 08:41 AM

Putting this in the perspective of fuel savings, if you drove 100,000 miles in your rig at 15.97 MPG over 13.1 you'd save about 1372 gallons of fuel.

Some of us are really pleased with ourselves - me included - when we can take our 50 MPG and bump it up to 60 MPG. but over 100,000 miles, that's only saving 333 gallons of fuel.

Most people don't use motorhomes as daily drivers, but if you travel a lot, your aerodynamic improvements will net you HUGE savings!!!

orbywan 07-18-2011 09:38 AM

Quote:

Originally Posted by thatguitarguy (Post 250860)
Putting this in the perspective of fuel savings, if you drove 100,000 miles in your rig at 15.97 MPG over 13.1 you'd save about 1372 gallons of fuel.

Some of us are really pleased with ourselves - me included - when we can take our 50 MPG and bump it up to 60 MPG. but over 100,000 miles, that's only saving 333 gallons of fuel.

Most people don't use motorhomes as daily drivers, but if you travel a lot, your aerodynamic improvements will net you HUGE savings!!!

I don't drive it much now but it's good knowing it's efficient for it's size. I still have to finish the A/C unit, skin the undercarriage (that's going to be serious fun) and do some mods to the front so I'm hoping there's better numbers ahead. Time will tell.

I was surprised the Dryden tests didn't show better numbers for rounding off the front, so I went after the tail first. I found another chart on a truck products company's web site, which I can't find at the moment, that shows rounding a brick shape object in the front reduces Cd by 50%, which I think is the way the average Joe thinks, including me until I tried the boat tail.

Anyway, I'm going to try several things up front, there's serious room for improvement there also.

skyking 07-18-2011 09:54 AM

Don't worry about the front, the dryden test and all the wind tunnel data scattered all over this site says otherwise. The 'money' is in the back :D

slowmover 07-18-2011 05:56 PM

Split A/C unit

Here's one post from a long thread on AIR regarding a split HVAC unit on an Argosy travel trailer (also diesel powered, no propane). Argosy was the bargain version of an Airstream, painted instead of shiny. (A custom build by a highly knowledgeable owner stretching himself. His tow vehicle carried a Mini Cooper and pulled the trailer. Great read).

aerohead 07-19-2011 06:00 PM

airdam
 
Quote:

Originally Posted by orbywan (Post 250646)
I didn't mean it's never been done before, I've just never seen one on an RV, except in PhotoShop. An 18" boat tail seems really short, but it was a short vehicle, goes to show how much they make a difference I guess.

Doing a belly pan on this RV is going to be a pain but I kind of have to finish it. If I put a full pan on it, should I also make a front air damn?

Both my CRX and T-100 both showed an improvement with an airdam even though they are both bellypanned.
Ford's Probe-IV had an active deployable airdam which lowered at speed to block air from under its fully bellypanned underside.
Many of the lowest drag concept cars will at least lower the car at speed to reduce airflow underneath.
So that's kinda a 'yes' for the airdam.

aerohead 07-19-2011 06:11 PM

radii
 
Quote:

Originally Posted by orbywan (Post 250865)
I don't drive it much now but it's good knowing it's efficient for it's size. I still have to finish the A/C unit, skin the undercarriage (that's going to be serious fun) and do some mods to the front so I'm hoping there's better numbers ahead. Time will tell.

I was surprised the Dryden tests didn't show better numbers for rounding off the front, so I went after the tail first. I found another chart on a truck products company's web site, which I can't find at the moment, that shows rounding a brick shape object in the front reduces Cd by 50%, which I think is the way the average Joe thinks, including me until I tried the boat tail.

Anyway, I'm going to try several things up front, there's serious room for improvement there also.

Moller improved the Volkswagen 'brick' from Cd 0.76,to Cd 0.42 with front radii.
Walter Lay,in 1933,built a full-size brick on a GM truck chassis.Leading edge radii cut drag from Cd 0.88,to Cd 0.42.
In 1963,GM investigated 18-wheeler drag.A fully radiused front was just a smidgeon ( sp?) better than an 18-inch radius.
In 1936,Fachsenfeld modified an Omnibus bus,with an inflatable boat tail which brought the drag down to Cd 0.158.His tail is the best I've seen so far.It's in Hucho's book.
The NUNA-3 team boat -tailed 'everything' on the car and achieved Cd 0.077.
The back really is where the pot-of-gold it hiding.

orbywan 07-19-2011 08:06 PM

10 Attachment(s)
Quote:

Originally Posted by aerohead (Post 251114)
Moller improved the Volkswagen 'brick' from Cd 0.76,to Cd 0.42 with front radii.
Walter Lay,in 1933,built a full-size brick on a GM truck chassis.Leading edge radii cut drag from Cd 0.88,to Cd 0.42.
In 1963,GM investigated 18-wheeler drag.A fully radiused front was just a smidgeon ( sp?) better than an 18-inch radius.
In 1936,Fachsenfeld modified an Omnibus bus,with an inflatable boat tail which brought the drag own to Cd 0.158.His tail is the best I've seen so far.It's in Hucho's book.
The NUNA-3 team boat -tailed 'everything' on the car and achieved Cd 0.077.
The back really is where the pot-of-gold it hiding.

OK, Iíll play with the air dam when the belly pan is finished, thanks for the information Phil, and everyone else for weighing in on this, the comments and advice are very appreciated. I know enough to be dangerous at this point. I just spent the last few days before and after work building the front part of the A/C fairing, photos are below.

It was probably more trouble than it was worth but I wanted to add a rear looking roof cam to my system and this way I was able to incorporate that into the fairing. Itís kind of long but I still have room for solar panels. Probably would have been easier to just take it off and relocate it but itís done for now.

skyking 07-20-2011 12:30 AM

Good looking work there man. Pic #6 took me back to 1977, R2D2 in the x-wing fighter :D
Shark-gill louvers on the back should allow the AC to work with that fairing on.

orbywan 07-20-2011 09:38 AM

Quote:

Originally Posted by skyking (Post 251163)
Good looking work there man. Pic #6 took me back to 1977, R2D2 in the x-wing fighter :D
Shark-gill louvers on the back should allow the AC to work with that fairing on.

I love those domes, they're perfect for small stuff. Now that I've got an extra camera feed up there I can vent the rear cover and remove the tape from the A/C unit, mount a camera off to the side temporarily and watch it as it goes down the road to see if it's over pressurizing the cover or trying to come apart.

Once I'm sure the A/C unit can work properly I'll rebuild the rear cover with metal. That or remove it all together and replace it with a split unit like the one in slowmover's link, or a heat pump mounted in the top of the boat tail. This will have to do for now.

Next up is finishing the belly pan. This is where I wish I had a hoist.

aerohead 07-20-2011 05:59 PM

Cd 0.07 AC unit
 
Quote:

Originally Posted by orbywan (Post 251137)
OK, Iíll play with the air dam when the belly pan is finished, thanks for the information Phil, and everyone else for weighing in on this, the comments and advice are very appreciated. I know enough to be dangerous at this point. I just spent the last few days before and after work building the front part of the A/C fairing, photos are below.

It was probably more trouble than it was worth but I wanted to add a rear looking roof cam to my system and this way I was able to incorporate that into the fairing. Itís kind of long but I still have room for solar panels. Probably would have been easier to just take it off and relocate it but itís done for now.

According to Sighard Hoerner's book,your AC unit,with fairings should now be down around Cd 0.07.There is nothing lower out there.Sweet!:);):thumbup:

orbywan 07-20-2011 06:23 PM

Quote:

Originally Posted by aerohead (Post 251289)
According to Sighard Hoerner's book,your AC unit,with fairings should now be down around Cd 0.07.There is nothing lower out there.Sweet!:);):thumbup:

Cool, thanks Phil.

slowmover 07-21-2011 01:26 PM

Quote:

Originally Posted by orbywan (Post 251296)
Cool, thanks Phil.

Yes, thank you!


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