Dumas AVL questions

[Kez]

Ready to continue the Dumas AVL in the coming building season. Two questions:

1. The front wing (or canard?) of the Dumas kit is a simple wedge shape. I have never seen the real boat but would think the front wing should be an inverted airfoil shape. Can you scale buffs confirm how the front wing is like on the real boat?

2. Dumas kit has the little recess in the tunnel floor at the transom. This is one of the few areas I deviated from the stock Dumas kit, I cut a new transom and the bottom has no recess on mine. I am just curious to know if the real boat has this recess.

Thanks,

kez

 

[Chris Thomas]

You are correct on both areas. It is not a triangle shape for a canard. I will have to look if it was 'inverted' or moveable for that matter. I believe it was 'fixed'. And if you plan to run IMPBA scale you are not allowed to have the transom cutout.

 

[Hydro Junkie]

I'm assuming this is the 1982 version of the Atlas and, if so, the canard DOES NOT have an inverted airfoil. The airfoil is actually symmetrical with the trailing edge curled upward slightly and was hardmounted to the sponson inside and cockpit side

 

[Kez]

Thanks Chris and Mark for your replies. The photo confirmed that the front canard is not a triangular shaped wing. It does look to have an airfoil section to it. I can also tell there is no transom recess in the real boat.

I can see why Dumas would use a wedge section front wing for simplicity. But I can never understand why they would go through the trouble to put the transom floor recess.

kez

 

[JimZaremski]

I wish you luck settling this beast down. I've posted about my travails with this hull. With the Dumas running hardware it's useless. With aftermarket hardware it's serviceable but IMO not raceworthy. You'll have to modify the underside of the hull quite extensively if you want it to be a runner.

 

[Kez]

Jim,

I have incorporated changes with suggestions from this forum.

1. Remove the transom floor recess.

2. Front radio box and put the fuel tanks under the deck.

3. Reduce the sponson depth by not installing the pads that the plans call for

I have already built the front canard or I would have made a new one with an airfoil to make it close to scale. I am also tempted to change the sponson angle (AOA) and non trip.

I will be using Speed Master hardware. I hope to finish the hull this coming building season.

kez

 

[Hydro Junkie]

I know most, if not all of Roger Newton's plans have the sponson runners at 3 degrees. I'm don't know what your Atlas is at from the factory but the 3 degrees range would be a good place to start