New to Modeling

[Phugoid]

I would say try the kit rubber, but be prepared that you will not get as long a flight as using after market rubber- like Wildpig said, the Guillows strip is more powerfull,

I wouldn't say it is more powerful, the Guillows rubber isn't nearly as stretchy as decent stuff, this means that with few winds it starts to go tight, and thus when you let go of the prop you get a big (and undesireabe) power burst followed by a very short motor run. It simply cannot store the same amount of energy decent rubber can.

I can't say that I would recommend the 900 kits for a complete beginner. They are fun in many ways but the are weak especially where the wings join the fuselage. Also being a low wingers (apart from the bird dog) they can be tricky to trim.

The Little Cessna 180 can't be beat for a first out scale model IMO. When they laser cut it, it will be an even better kit. It even comes with a suitable sized prop, and is very very easy to adapt to have a removable noseplug as I did on my build.

Which ever you go for, Aim for a high wing or sports model, you are much much more likely to get it to fly.....

[Billy Mc]

The 600 series are easier to build than the 900 series. I've heard the 700 series are also easy to build.

[Acorn Man]

Ok, thanks. Can I replace the rubber or change it out after I finish it? Thanks for the adice on not making an underwing model, I hadn't thought of that. On thing I don't know how to do is trim and adjust for the torque of the propellor, or for the thrust angle (I don't even know what that is). Thanks.

[Wildpig]

Ok, thanks. Can I replace the rubber or change it out after I finish it? Thanks for the adice on not making an underwing model, I hadn't thought of that. On thing I don't know how to do is trim and adjust for the torque of the propellor, or for the thrust angle (I don't even know what that is). Thanks.

Yes, you can change the rubber motor after you finish the build, if you provide the proper access openings. The cowling or thrust button needs to be removable, not glued in place and it helps to have an opening in the bottom of the model, just below the rear motor peg. What I do is feed one end of the rubber loop through the opening in the bottom of the model, the put a long hook (coat hanger) down the nose and hook the rubber loop. Insert the motor peg through the loop end,also. Then pull the rubber motor to the front of the model. If you see it done once, you'll see it's easy to do. There are other ways, some guys use what I think is called stuffing stick.

Here is a copy of my trimming instructions:

I

*Get the model balanced properly according to the plans*.
Next, you will probably need to add a trim tab on the elevator. Check out Mitch's thread with his 400 series P-51 and other WWII models. Search the forum for: trim tab
You want the model to have a shallow, slow glide. No pitching up and down and no rolling to the left or right, either. This may require a trim tab on the rudder or on a wing.
*Keep making test glides, preferably over tall grass,adjusting the trim tabs until it has a nice steady glide.*

Once you have a glide set up, lets just say that it glides at a steady 4 mph. When you wind that rubber motor and let the model go; now the rubber motor tries to propel the model at say...20 mph. But, the model is trimmed for 4 mph (from the glide tests).The only way it will stay at 4 mph is in a climb. With a balsa model that is usually a very steep climb and sometimes will even do a loop. The 4 mph example is known as it's trim speed. An airplane will always try to fly at it's trim speed. This principle is true for any conventional airplane, regardless of size.

The bad part is that this steep climb leads to a stall and usually the model plummets straight into the ground and then you have a very discouraged balsa modeler.
To counter this effect, just add a downthrust shim under the thrust button. Search the forum for: downthrust shim.
You kind of have to guess with the amount of downthrust but, a 1/16" square strip of balsa stuck under the top edge of the thrust button will probably be plenty. Might have to shave it a little thinner. This shim causes some of the propeller thrust to pull the nose downward slightly during flight, countering the upward pitch trim.


Questions???

[Phugoid]

Down thrust doesn't counter too much speed, it does pitch the nose down, but if the model flies too fast to the point where it loops or stalls that much the rubber and prop combination is incorrect, at than point the first thing to do would be to use a longer/thinner motor.

The key to finding out if you need more down thrust is observing the flight. If the pattern is stall then a recovery then a steady(ish) flight then the model requires downthrust. If it continues to stall recover, stall recover, then initially at least it needs more noseweight or some trim tabs.

Andrew