ARGH! Friggin' Cowl Indecision -- James or Van's

This is a forum to ask questions regarding the different models of Vans Aircraft. If you are having problems deciding which one to build, this is the place to go.
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aparchment
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ARGH! Friggin' Cowl Indecision -- James or Van's

Post by aparchment »

I have been very clear about what I want out of this airplane until now. I have been hung up for a while on my cowl decision and it is very frustrating. It just cost me $150 since I didn't get my Van's order in before the price increase.

I am going with an IO-360 with horizontal induction and constant speed prop and I am struggling over whether to buy a Sam James cowl or go with the Van's. The problem is that I don't want a snorkel or any sort of air intake that protrudes from the cowl. To make matters worse, I don't want to lose manifold pressure from an inlet fed induction. Yeah, I want to have my cake and eat it too.

Do you guys have any pics of the James cowl using induction air off of the intake and thus doing away with the snorkel? There was a good thread on this recently on the Yahoo James group, but I didn't see any pics associated with it.

Here are the pics I have, along with some comments:

Good looking plane with James cowl, but the snorkel has to go!
Image

Mark Manda's great looking 7A with NO SNORKEL and Van's cowl. Beautiful!
Image

Gorgeous 6 with interesting inlet. This might be a good option to ensure good manifold pressure.
Image

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JohnR
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Post by JohnR »

I had planned on going with a SJ cowl and when it came time to order the finish kit I changed my mind and bought the Van's cowl. I am putting in an IO-360-M1B also and like the looks of Van's cowl better I decided. Plus from what I've read it is easier to work with.

I know it doesn't answer your questions but that is where I ended up. Good luck!
JohnR
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bullojm1
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Post by bullojm1 »

OK, first off, we need some definitions:

SNORKEL : This is an internal duct that takes air from the right cowl intake and directs it to the intake on the horizontal induction. Pic of the Snorkel is:

Image

SCOOP: This is on the bottom of the cowl and is used for the air intake for vertical induction engines.

RAM AIR INTAKE: This is a intake on the front of the cowl, above where the scoop would be. This is used to bypass the weaves the snorkel takes to get air into the engine with less resistance (i.e. to try to get higher MP).

If you are shooting for a IO-360 with horizontal induction, it won't be a problem to get the James Cowl without any extra holes in it. One example of this cowl is on their site:

Image

In the pics you listed, the first plane has a vertical induction engine, therefore requiring the scoop. Mark Manda's plane has a horizontal induction without needed an external scoop (has an internal snorkel).

IF you go with the James Cowl, you are forced to use their Long Cowl with horizontal induction. The implication of this is you will either need a prop extension (Sabre Mfg makes them: http://www.sabermfg.com/extensions.htm ) or an extended hub c/s prop. I know with the Sabre extension, aerobatics should be limited to either 3-4 G's because the prop is hanging forward more and will undergo more stress. I don't know if the same recommended limitation affects extended hub c/s props.

As far as having your cake and eating it too....Dan Checkoway (http://www.rvproject.com) had to fabricate his own snorkel. After he was flying, he compared his snorkel MAP to his Ram Air MAP and found __his__ snorkel was super efficient, withing 1/2" of the ram air. His full story is here: http://www.rvproject.com/20050426.html

Also, be aware there is a waiting list for the James cowl. I have been waiting for my turn since the end of October!
Mike Bullock
http://www.rvplane.com
RV-7 | Superior IO-360 | Whirlwind 200RV
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aparchment
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useful

Post by aparchment »

Great comments Mike. Thanks also for clarifying my terminology. I tend to play fast and loose with terminology in general, and it plays to my disadvantage sometimes.

Antony

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captain_john
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Post by captain_john »

Antony,

If you come down Sunday, Mitch will urge you to go with Van's cowling and Jack will show you his James cowl. You will have some ammo for decision making.

They are good guys and pretty funny when you get them together.

I have the standard Van's cowl. My strategy is brute force. I am going to install extra power and minor losses are acceptable because of the surplus of power at hand.

Extra power is the 390.

Minor losses are standard cowl, extra engine weight, heavy avionics and the standard filtered airbox. Perhaps that muffler we have been speaking about too is considered a loss to me as well.

Check out Jack's intake. His James intake is really slick! He did a really good job of assembling it.

Then again, 1/2" of MP isn't really much for all that work.

My two...

8) CJ
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bullojm1
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Post by bullojm1 »

Antony,

Another thing to consider is price. For 2007, Van's gave me a $750 credit for the cowl and the hardware specific to it (oil door, etc). The James cowl runs $950 + Liz James quoted me a little over $100 to ship it to Maryland.

I am going with the James Cowl. It seems to be the best bang for the buck for **theoretical** speed increases. Plus it looks cool. In the end, isn't that all that matters?
Mike Bullock
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RV-7 | Superior IO-360 | Whirlwind 200RV
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cjensen
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Post by cjensen »

Yeah, with the price increase at Van's effective, the two are really pretty close now.

I'm going SJ strickly based on looks, and if I get a little boost because of the plenum (whether perceived or not), all the better!

8)
Chad Jensen
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