Rudder Offset

While reading the post "Adjustable Leadout Question", some discussion about rudder offset was included. I think the general consensus is that you usually don't need it, but some put a little in anyway to "make sure".

My question is, MUST you include it in an OTS design that clearly indicates an amount on the plans? Of course I don't mean for flying purposes, just for "rules" sake. Some of those old designs used quite a bit of offset.

I don't remember seeing that question addressed previously.

Thanks,
George

Rudder offset is a trim question, not a design question. You are allowed to adjust the rudder so long as it is there, but you are not allowed to resize it. Same with flaps, elevators, etc. You do not need to use the same ratio of flap to elevator, or total amount of throw, even, but you do need to keep the same areas. (Although there is some "fudging" occasionally, where someone adds a "trim tab" to the outboard flap or to both elevators for the purpose of adding a little area to an appropriate spot.)

Leonard Neumann

That is a good question. I don't understand rudder offset as being listed as a "non-modifiable" under PAMPA rules. It seems to me that allowing adjustable leadouts implys freedom to do what one wants with the rudder. I've included "some" rudder offset in most of my OTS airplanes where offset is called for. Not as much as called for, but a little for cosmetic effect. My personal thought is that it is not something for anyone to be concerned about.

I have a Barnstormer and out of habit and old style stunt I put it in as the plans said. I have since taken out all but a few degrees of rudder offset. It is not needed. In the "old days" very few understood what all that off set actually did. Now we know, it made things worse. It is a matter of trim, not rules as long as the rudder is the size indicated on the original plans. Mine flies much better than my first two.

Thanks for the replies. I think I'll go with just a little offset for looks.
Since I can't stunt fly well enough to be good yet, I will go for different. I have my eye on two OTS designs.
The first is the Ginger Snap, as shown in the OTS PAMPA book. I got a long stroke Mills 1.3 replica diesel ready to go in it.
The second is a Stunt SE5 from a 1947 model mag. It has a 28" span. I can't find its plans available so I'll take the mag to a blue print shop and see what they can do. I COULD just scale it up 4x. The author stated that he could even do outside loops with it ... He used some unique features like two "D" flashlight battery cases soldered together as a tank, and using grease fittings (zerks) with the springs removed as check valves so the tank could vent both upright and inverted. The original used a Tiger Aero engine but I'll have to use something more modern that matches the power.

George, given the tank setup on the Ginger Snap, it might do an inside loop. I have plans for Ron Prentis' "Small Fry", which won the British Gold Cup stunt contest in 1948 with a Mills 1.3. It has a stick and tissue fuselage and rubber-banded on wing. I've buit the similar "Big Fry" with an ED 2.46 Racer and it flys the OTS pattern without difficulty. I'm into SE5a's and would be interested in a plan swap. [email protected].

Thanks, Jim

I go to Kinkos and use a copier that does 200% and make copies, usually 3, until I get full size. Usually there is a scale on the plan. I use it to make sure I'm within 1/16". The ink lines can compensate for that. That is how I scaled up a Wee Duper Zilch and a few others for OTS and classic stunt. At 10 cents a copy, real cheap. They don't charge for the ruined copies you throw away.

The two Kinko's I use have machines that will copy up to 36 in wide and as long as you like. The machine will enlarge up to 200%. It's around $3.00 for a copy. I understand there are more sophisticated machines which will copy the lines at the width you want rather than just scaling them up (or down). A blueprint shop would probably have one of these machines.

Wow. Two Kinkos!! I guess I better start asking some questions of the lady that runs the counter. She always seems so harried I hate to bother her and just go to the machine I usually use. Thanks for the info. Ty

I've had good luck with my local printing office. They specialize in architectural drawing copies, and it's not a self serve.
Copies run $2.50 - $4.50 so far, depending on size. I'm not sure what they charge to blow them up. If it's too much I may go for blowing them up, then having the paste-up copied.
Or I could just scale it up from the mag as I build (plan C).
Jim, it will take a few days to look into this, probably next week. The SE 5 is from June 1947 Model Craftsman, and was designed by Joseph Flor. The wingspan is listed as 28", but a 4x plan will yield about 27 3/4" which, looking at other parts, I think is correct.
George

Self service at Kinko's works pretty well. But one time I accidentally set the machine to make 200 copies rather than 200% enlargement. Fortunately help was nearby.

Jim,
As luck would have it I was able to get to the repro shop today. The first blow up (34"x44") cost $7.80 and the next copy was $4.80, so they charged $3.00 to make a copy from the mag and blow it up. Not bad I'd say.
The wingspan did come out to 28" at 400% blow up...and the 2 1/2" wheels are 2 1/2". We're there.
Send me your mailing address and I'll send you a copy. Your offer to trade for a set of the "Small Fry" plans sounds good.
Gotta put that Mills 1.3 replica in something.

I've had copies made up to 400% at a local blueprint company. They print on 36 in. width paper for whatever length is required. They print directly from a magazine page size to get the enlargement. For very small sizes plans I've had a 200% copy made at the convenience store for $ .10 and then took this to the blueprint shop.

The prices so far have been in the $7 to $8 range. If you want a truly "permanent" copy they can do it on a Mylar product which will not stretch or shrink. It is supposed to be very long lasting.

Jim Thomerson has had better luck with Kinko's than I have. The one near me is very short on "service" if you need help.