I've noticed a diversity of opinion about whether engine offset is "required", or preferred, or even desirable for either rotation.  The benefits and drawbacks of offset interact with all the other tricks we use.  

I would guess that for a plane that you have tested and trimmed with some engine offset -- you should have more line tension if you change to a reverse rotation engine.  Then your score may benefit from reducing or eliminating the offset.

If I was building a new plane with reverse rotation,  I would start with no offset.  Theoretically, reducing the offset will increase high speed score and allow for less yaw variation (wagging) due to throttle changes during low speed.

Randy

I have flown a lot of reverse engines and usually start with less out thrust, then it becomes just another trim point, some planes like more than others. You have a bit of a compromise between high and low, and a lot of factors like tip weight and slider geometry in addition to out thrust.

What about tip weight? Wouldn't reverse rotation torque the outboard wingtip down with less or even no weight?

The point of adding a weight on the outboard tip is so that it balances the weight of the lines on the inboard.

Precession from a rotating mass is another matter entirely.

The weight of the lines, I knew that at one time, I guess the ol' file cabinet is getting a little disorganized.

Hi Duke, thanks. I believe I've seen pictures of your fleet over at CEF.

Ive never run a reverse rotation crank except in very brief tests with an electric motor.  Frankly couldn't see enough difference to make it worthwhile.  The best advice would probably be to try it and trim as needed.

There is the misconception that tip weight ONLY has to balance half the weight of the lines - that any more is too much.  Even in a stunt plane, tip weight must balance part of the weight of the lines but it must also help cancel out the lift differential due to the outboard wing flying faster than the inboard wing.  In a carrier plane, flying very fast, we don't really care about that.  And flying very slowly the lift differential is probably too small to worry about.

So what's the reason then that we need perhaps 2 oz. of tip weight?  Well, when we pull the nose up to 45 or more degrees, the tip weight helps to ROLL the plane outward and also to YAW the nose outward.  Obviously, both are aids to keeping lines tight, and thus control, at very low speed. The downside is that lots of tip weight causes large yaw forces at takeoff (basically the engine tries to fly around the tip weight), which causes skidding, poor accelleration and poor takeoffs.  One can help that by trimming the wheels and by avoiding too much up elevator, to get the tail flying and to maximize accelleration.

As to the outthrust question originally asked, I use quite a bit of outthrust using thrust wedges - I find it helps keep the 'yo-yo-ing' to a minimum and once in the hang, when you goose the throttle it just seems to make things operate a little more smoothly.  It must cause some loss of high speed, but I doubt if it's more than 1 or 2 mph.

Mike Anderson- Thanks for you thoughts.  I haven't met you before. I was thinking of Bill Bishoff and Mike Potter when I asked earlier.  Not that you didn't have some great stuff there.

I think I'll spend some time looking up model carrier landing videos on the Tube. Sounds interesting, a whole 'nother world in CL I haven't been exposed to. I'll start with the Youtube links under some of your avies. I like the "Unread Posts" link at the top. It gets me into forum sections I might not have otherwise visited.

Rusty
Here's a link to start http://www.controllineworld.com/whatiscarriercl.html . And at the bottom of that page click on the link to the NCS or use this one. http://www.navycarriersociety.org/MainMenu.aspx

There's some good starting info on those links.  I might be able to dig up some beginner plans.

Good links, Duke. That answered some of my questions. I always imagined coming onto the deck at a high speed, but now I see I was wrong about that. But the planes still have to be able to flat out haul ass. First 6 laps are timed for points I presume. Then I guess you get points for how slowly you do the final laps before landing.
I learn something new every day.

Thanks for the info on this topic.  I knew it would be a trimming variable that would need some experimentation, but I was looking for a starting point.  The plane is a new Avenger that I designed some time ago but the last 5 years have involved alot of moving around that hasn't allowed me to do much flying.  My only experience with LH engines comes from 1/2A profile proto speed where it makes a huge difference in how the model behaves on take off.

     If I can make it to Des Moines I will.  Starting a new job that should be a little more stable.  Unfortunately, I have to go to Minneapolis (Indoctrination) and Cincinnati ( maintenance type training on CRJ) before I can start work and the feds haven't cleared my finger prints yet.  I didn't think I was a nogoodnik, but you never can tell!  Maybe they are busy with other fish to fry these days and forgot about me.

Had something interesting happen today re tip weight and reverse props. I was flying my AMA class Seafire electric profile. Prop was an APC 9x6EP. Just a slight bit of engine offset is used. It was  light on the lines and was not hanging quite right. I moved the balance to the rear, and it helped but still not as solid as I like. I figured maybe a bit more tip weight would help.

I then found out that I didn't have any tip weight. apparently I had taken if off while working on the plane for some reason and never put it back on.

The point is Reverse props can cover up a lot of problems and errors. I think they are very worth while and with electric absolutely easy to use.