Hi,
    In several posts on this forum and also in the specs of many listed models we see the wing span and fuse length specified. Is there any specific relationship between the two? When building a model of your own specs how do we choose the two?? For example, what would be the flying characteristics of a model with a long wing span and short fuse or vice versa.

would be interesting to know about this.
For me, I prefer planes with a long tail. most of my planes have a fuse length equal or more than wingspan. Helps in pattern

That is an interesting question. Here is what I inferred from my experience.

I usually have the plane fuse about 1.5 to 1.75 times the wing span. The tail moment would be moderate for this configuration. This would yeild a plane with normal response on the tail feathers. So, you can have relaxed flight with or without requirement for exponentials (depends on the control surface area). Normal trainers, warbirds and most other aerobatic sport planes fall under this catagory.

For planes with longer fuse more than or equal to the wing span. The tail moment is quite high. The tail has to travel longer displacement to make the same effect comparted to a short tail airplane. So, they tend to be a bit slow and has finer resolution on tail control surfaces. This is desirable for precision flying as the pilot would have sometime to react and plan the maneuver. High tail moment will be desirable for sharp, precise and crisp aerobatic maneuvers and they are also good for 3D flying. esp during hovering.

As a simple analogy, its easier balancing a longer pole on your finger tip than balancing a pencil. You can make a few errors in balancing a longer pole as the moment is high. But for a pencil even a small displacement is enough to topple it.

I observed that most patterns have fuse length equal to wing span.

-Ismail

Quote from: izmile on December 02, 2009, 04:21:36 PM
That is an interesting question. Here is what I inferred from my experience.

I usually have the plane fuse about 1.5 to 1.75 times the wing span. The tail moment would be moderate for this configuration. This would yeild a plane with normal response on the tail feathers. So, you can have relaxed flight with or without requirement for exponentials (depends on the control surface area). Normal trainers, warbirds and most other aerobatic sport planes fall under this catagory.


-Ismail

I suppose you mean 0.5 and 0.75  not 1.5 and 0.75

Yes, that was a mistake. Thanks Sai.

I meant 1.5 to 1.75 times of half the wingspan. Sorry for the confusion.

-Ismail

When we determine the length, is the fuse length calculated along with the elevator end?
Anyrelation of the wingspan to the chord?

Pankaj

 Pankaj

I am attaching a diagram which I hope would be of some help.Using that diagram I have successfully built a trainer plane. It is not my drawing but copied from a book named Building & Flying Radio Controlled Model Aircraft written by DAVID BODDINGTON. I purchased it from a second hand Pavement Books shop in Hyderabad approx about a decade ago when I was just beginning in this hobby.It is a wonderful book for RC Modelers.
Hope the drawing would be of some help to you.

Rao.