We are building Ziroli 118" B-25. It's all framed up and we are installing the hardware prior to final finishing. It has 2 G-45's so it has plenty of power.

The question is:

Are the rudders supposed to be set at "0" straight ahead or should they be toed in or out?

We just got done photographing a full sized B-25 up close and I can't see any "toe" on the rudders. We took a bunch of pictures. It looks straight ahead to us.

We'll be using a gyro on the rudders and possibly on the ailerons, both will be able ot be adjusted from the transmitter.

thanks

Hi bentwings
I have never heard/read about having the rudders offset. What is frequently suggested is putting in a generous amount of "out" thrust on each engine. I had 3 to 4 degrees on mine (not a B-25) to help in the engine out situation and some even recommend more. You need a firm plan on what to do in an engine out situation. I suggest you read everything you can in the Multi Engine Forum about engine-out prior to your maiden flight. I can still remember the first R/C B-25 I saw in the air. I was fascinated. After a few laps one engine quit. It was very sad. The pilot, an expert to the rest of us, probably thought that with his skills he could manage the situation. He could/did not. It was 100% totaled. When I fly a twin I keep repeating ONE ENGINE OUT ALL ENGINES OUT and land where I can. I get a helper to yell that in my ear if I forget. There are many twin experts (I'm not one of them) at the Multi Engine Forum, below, who can be very helpful if you ask them. I'm looking forward to a report on your maiden flight.

Thanks for the info. We have done all of the above except the out thrust. Z says straight up is best on his plane unless noted. This is probably the "squarest" plane we have ever built. Everything is measured about 10 times before lockinging stone. Everything possible has been done to assure a good flyer. I have flown twins as a daily flyer back when twins were not cool. Some of them had more engine out time than twin time. haha Some didn't live long either. Hopefully that's past.

The Z B-25 is supposed to be one of the best of the twins as far as flying. We even have it on a flight sim. Both of us can handle it nicely there even with 15 extra pounds so we are hoping for the best. We practice engine out all the time. Especially unexpected ones. A heavy B-25 low and slow with an engine out gear and flaps down and severe cross wind is lots of fun. haha. Both of us "fly rudder" all the time so we are not elevator and aileron only guys.

The question came up from a guy who is a self proclaimed "expert" who has only flown a twin in his sleep. I felt it was a logical question however since I had not considered it. We think straight up is best and that the gyro will give the extra 2 seconds needs for corrective action in an engine out. We have very fast and powerfull servos on the rudders as well the top of the line gyros. We've flown all of our warbirds with gyros on the rudder and they work great properly set up.

Sounds like you have it well together. Nostalgia makes me love the B-25. I got a hop on one in 1955 from a National Guard base in Kentucky or Tennessee to Newark Airport. We circled the Statute of Liberty twice before landing. Hope to read about your maiden soon.

In theory, if you toe-in the verticals a little, you get some help if an engine quits. Basically, the prop blast from the one running engine will result in more airflow over the vertical on that side, and if that vertical is angled, then it gives the same result as rudder deflection. If the verticals are toe-in, then the right vertical is trying to turn the plane right, and the left vertical is trying to turn the plane left, and they cancel out if they have the same airflow. Apply asymetric airflow, and you get a yaw that works counter to the yaw of one engine out.

However, from what you've said, it's probably not worth it. And certainly the full-scale didn't do it. (probably because on the full scale, it would add a bunch of extra drag in normal flight, which would not be worth any benifits with an engine out). You'd get better scale looks from out-thrust, which is harder to see. And you said you're using a gyro.

Also, take a look at the "Twin Synch" device, if you haven't already.