Aero RV (custom boat tail for '95 Ford E-350 Class C motorhome)

[orbywan]

Originally Posted by skyking

The low wing planes I flew would get stuck like that, you have to land to get them closed.
The high wing planes were a little more cooperative. You could always mess around with some rudder, induce a yaw that would alter the flow in your favor.

All you have to do is stall it, it'll close no problem.

[skyking]

LOL, true that. I try not to stall the 310 with passengers onboard

[orbywan]

Originally Posted by skyking

LOL, true that. I try not to stall the 310 with passengers onboard

Twins are scary for me since I've only flown two, but I used to love to get up high in an Archer or J-3 or whatever, and just 'mush' just above a stall. It gives you a great feel for when and if they might let go when you're low and slow and it counts.

I think flying in that configuration for several hours (total, not all at once) should be mandatory for all pilots, GA and commercial. Off topic, sorry.

[skyking]

Your thread, and I took it out in the weeds :P
I have a smidge more multi than single engine time, but I have 400 hours flying banners at 45~60 MPH at all times. I agree on slow flight, I lived there.

[orbywan]

Originally Posted by skyking

Your thread, and I took it out in the weeds :P
I have a smidge more multi than single engine time, but I have 400 hours flying banners at 45~60 MPH at all times. I agree on slow flight, I lived there.

I miss flying, had to give it up to start my business, not enough $ to go around. Hope to return to it soon. Thanks for the comments.

[Geo Metropolis]

It seems the general consensus has been to choose belly pan or air dam, not both, so on my metro I only did the belly pan and saw good improvement. Then after a while I added an air dam and saw even more improvement in mileage and especially handling. The metro has a high stagnation point and forces a lot of air to pressurize under the car which led to unpredictable handling with the belly pan alone. By adding an air dam that lowered my stagnation point to the same level as the belly pan, air is no longer pressurized under the car. Instead, the majority of air is pushed over and to the sides the rest slips easily under the car with the belly pan - my handling has improved dramatically and I've seen good mileage results.
I suspect you would see a good result with the belly pan, and an even better result if you add an air dam. I originally tried to make my air dam really low which was a mistake as I busted it to smithereens. It seems that belly pan height is perfect and this allows it to clear curbs, driveways, and off road situations easily. I suggest you angle it like a wedge and curve it toward the sides of the vehicle as smoothly as possible so it forces air up and around the side of the vehicle. Cut appropriate grille openings if you cover the grill (I had to adjust mine a few times making bigger grill openings to accommodate high desert temps).
I've chronicled my build really well but gotten behind a bit so I don't have a writeup on my front air dam yet, I'll try to post it up soon.

[orbywan]

Originally Posted by Geo Metropolis

Cut appropriate grille openings if you cover the grill (I had to adjust mine a few times making bigger grill openings to accommodate high desert temps).
I've chronicled my build really well but gotten behind a bit so I don't have a writeup on my front air dam yet, I'll try to post it up soon.

Thanks for the input GeoM, I will try an air dam when I can get back to this. Let me ask you and everyone a question. The RV suspension has a nose down attitude. CamperBob visited a while back (thanks for the input Bob, I enjoyed meeting you) and commented that I might want to make some vertical panels running front to back (on the belly pan in the rear) to keep the turbulence down that occurs under there when the rear is higher than the front. I think that's what he said, if I got it wrong Bob I apologize.

Would anybody hazard a guess as to how much of an issue this is? I haven't been able to do any seriously valid testing since I did the belly pans but I don't think they made that much of a difference. I think what GM and CamperBob are pointing out may have something to do with it. What I'm considering is removing several leaf springs in the rear and installing air bags under the rear end so I can control the ride height regardless of load.

That's more of a functional issue than aero, but what the hell, it might help.

[skyking]

here's my take on that:
I think the area increasing underneath is a very good thing. This relieves pressure under the car, and it acts just like a good diffuser angle in that it happens gradually. I was going through Phil's pictures, and saw that one solar racer that had a tunnel in the back, an extreme example of what I am talking about.

[orbywan]

Originally Posted by skyking

here's my take on that:
I think the area increasing underneath is a very good thing. This relieves pressure under the car, and it acts just like a good diffuser angle in that it happens gradually. I was going through Phil's pictures, and saw that one solar racer that had a tunnel in the back, an extreme example of what I am talking about.

So you're saying the nose down attitude may be a good thing?

[skyking]

What are the measurements?
My truck runs from 10.5" to about 13", for example.