Aeromodifications for large motorhome

[crmears]

What would be a less lengthly option?

[skyking]

Does it have a supplemental fan? If so, you could proceed with a tail design anyway. Usually there is too much airflow over engines and through radiators, lots of wasted drag.

EDIT: I will be drawing up my folding boat tail design for my 5th wheel in the next week or two. It is a little shorter in height than your MH, but just as wide and blocky at the back.

[crmears]

Originally Posted by skyking

I think you are missing the boat so to speak Randy. Forget the nose, concentrate on the tail. Cheaper, easier, more effective according to all accounts.

I am beginning to come to that conclusion. It is more simple, cheaper, but I did not understand that it is more important. Is that a proven and non debateable fact, that the rear is more important than the front??

Randy in Spokane

[crmears]

Originally Posted by skyking

Does it have a supplemental fan? If so, you could proceed with a tail design anyway. Usually there is too much airflow over engines and through radiators, lots of wasted drag.

EDIT: I will be drawing up my folding boat tail design for my 5th wheel in the next week or two. It is a little shorter in height than your MH, but just as wide and blocky at the back.

It has a 3.5 ft. manual fan with a centrifical clutch. Have you tested your boat tail on the 5th wheel? Is yes then how much did it help?

[skyking]

Hard to believe, right?
Somebody posted info from a test using a brick shape. Fairing in the back was the single biggest improvement, and here is my take on why:
No matter how you smooth the flow going onto your rig, it still displaces X amount in cross section. Still 13 high and 8 wide. No way to fool that.
At the back you can "let" that air off very gently and efficiently, or let it slam shut.
If you let it slam shut the turbulence and vacuum is so great, a car can ride with almost no power input in the wake of your motorhome. IF you think about it, you could pull a smaller motorhome along behind you

[skyking]

Originally Posted by crmears

It has a 3.5 ft. manual fan with a centrifical clutch. Have you tested your boat tail on the 5th wheel? Is yes then how much did it help?

I just got here myself, and have not designed it yet, let alone built it.

[crmears]

Originally Posted by skyking

Hard to believe, right?
Somebody posted info from a test using a brick shape. Fairing in the back was the single biggest improvement, and here is my take on why:
No matter how you smooth the flow going onto your rig, it still displaces X amount in cross section. Still 13 high and 8 wide. No way to fool that.
At the back you can "let" that air off very gently and efficiently, or let it slam shut.
If you let it slam shut the turbulence and vacuum is so great, a car can ride with almost no power input in the wake of your motorhome. IF you think about it, you could pull a smaller motorhome along behind you

Airplanes (except for fighters) have a relatively blunt nose but a long slender tail. That seems to confirm the relative significance of the rear aerodynamics.

[euromodder]

Originally Posted by crmears

Is that a proven and non debateable fact, that the rear is more important than the front??

Yes.

If you need to streamline a brick, add a fairing on the rear ...
Counter-intuitive, but that's how it is.


There you go :

Airflow is going from left to right, BTW

[cleanspeed1]

Originally Posted by euromodder

Yes.

If you need to streamline a brick, add a fairing on the rear ...
Counter-intuitive, but that's how it is.


There you go :

Airflow is going from left to right, BTW

This is from a side view, correct?

[Frank Lee]

The tail could certainly be open to the rear for probably IMPROVED cooling flow.