Dave Sanders, of Dave's Aircraft Works, is our "resident" model aircraft expert.

Dave is renowned not only in the world of model aircraft design and construction, but in the use of EPP foam as well. Dave became widely known as the first to "make EPP beautiful," and as the first to make a conventional aircraft model from EPP, taking a step beyond the "flying wing."

Dave  is a pioneer in the use of EPP for model aircraft, and was amongst a group of leaders of the EPP modeling movement begun in part in 1997, from Dave's home in California, USA. He has designed hundreds of EPP model soaring and powered models, and has built and sold thousands of them. Dave arguably knows more about EPP model aircraft than anyone else in the world.

These Flying Facts are authored by Dave Sanders, and originated on his ground breaking website, www.davesaircraftworks.com.

After working seven years full time as an entrepreneur in model aircraft, today Dave Sanders is a home designer in Southern California. His passion for EPP model aircraft, however, remains as strong today as ever. We are pleased to bring you Dave's authorized website content here on EPP Hobbies.com.

D.A.W. Foamie Kit Performance Tips...

Trims and Balance...

Balance...

Proper balancing of any of your aircraft is absolutely imperative to achieve proper flight characteristics and ours are no exception! We specify in our manuals to balance the plane right at the spar location as a starting point, then move it from there to get what you're looking for. In this section on balance, I'm assuming your airplane is "straight" and all the control surfaces are "flat" at neutral. Here's some other tips to help you out:

• Moving the balance point (center of gravity, or C.G.) back will increase pitch (elevator) sensitivity and improve inverted performance on aerobatic planes. It will also improve light lift performance, to a point, by allowing the plane to fly at lower airspeeds before stalling. "Back" C.G. positions are frequently used by expert pilots for all the reasons stated above and many push them back as far as possible to make the aircraft just shy of un-controllable to mortals like us.
• Moving the balance point forward will make the plane less pitch sensitive, decrease inverted performance and require greater elevator surface deflection to change the plane's pitch attitude. This is a good thing for beginning pilots if they feel their plane is to "twitchy" on the elevator. This will, by the way, tame down the control authority in all three axes, although it's by far most noticeable on the elevator.
• In general, a 1/2" change in C.G. position either direction will result in an EXTREME difference in handling characteristics, so only move it a little at a time. The difference between "a little off" and "right on!" can be as small as 1/8". I usually change weight a quarter ounce at a time when testing a new airplane or even less on an HLG due to it's smaller mass.
• Add weight for balancing as far away from the C.G. as possible. For instance, if the plane is tail-heavy, add the weight as far forward on the nose as possible. I often balance my own planes by putting the weight in a hollowed out hole in the nose just ahead of or below the battery pack. On a tail-heavy model, I once hammered a little slug of lead into a stick that I jammed up into one of the cells in the Coroplast rudder. Placing the lead far away from the C.G. gives it maximum leverage and reduces the amount required overall, resulting in a lighter aircraft.
• For the first day's flying, I usually just tape the weight onto the nose so I can change it quickly, then alter it a little at a time until I get the plane just right and make other adjustments. After I'm finished, I embed the weights in a hole fuselage and patch the tape and covering over it.

Once you have the plane balanced to your taste, you'll check your idle trims.

Idle Trims...

By idle trim, I mean where the control surfaces are positioned when the plane and transmitter are turned "on" and at rest. For a plane that's just been finished, this should be flat neutral, of course. Before the first flight, here's some stuff to look for:

• Make sure the control surfaces deflect equal amounts in opposite directions.
• Hold a straightedge on the bottom of the wings out toward the tips - the bottom of the wing panel and the bottom of the aileron should align. This is the design idle trim for the plane in "outta' the box" mode.

Now, you'll go out and fly it and see what it does, and likely make some adjustments to your balance, transmitter trims and control throws. After those first flights, note the following:

• If the elevator has some slight "up" trim, you're on the nose-heavy end of the spectrum. If you added down trim, then you're on the tail-heavy end. Also, this can indicate decalage (wing-to-stabilizer relative angle) problems. If you're indeed balanced right on the spar, then adjust your balance a little until you get as close as possible to being able to have flat trims and a comfortable flying plane. If it's more extreme than that, then...
• Check the ailerons. First, are they deflected off-center? If they are, then there's some twist in your wing. This is no problem; you can twist them to the proper angle by simply placing adverse twist and heating the covering material with your covering iron - just as you would on a framed-up, wood wing. Now static trim your ailerons again fro neutral and fly it. You'll be able to get right on within a couple of times, and it should hold pretty well. The cores "want" to be correct, so you're really relaxing the tension.

Trailing Edge mixing...

On the warbirds and 1-26 HLG (aileron version only), you can increase performance by mixing the ailerons with the elevator to create a 'flaperon' setup. This means that when the elevator is deflected up, both ailerons will drop slightly to add camber to the wing. Obviously, this requires use of a computer radio and if you have one, it's definitely worth experimenting with. You can cut the plane's loop radius in half by use of this technique as well as giving the plane better climb and turn performance with less pitch attitude change. Very little downward deflection is necessary; as little as 3/32 inch (5 mm) droop of the ailerons with full up elevator will make a noticeable difference. Don't overdo it - too much mix will actually degrade performance.

Mixing the ailerons with down elevator can also be done, but generally doesn't yield as conclusively good results for all fliers. Take some time to try different settings and see what the results are for you. Many pilots will also setup an 'invert' switch which will raise the ailerons slightly when actuated. This slightly de-cambers the airfoil to allow the plane to fly inverted with less down elevator input.

Trailing edge mixing is not necessary on the TG-3, as it's airfoil doesn't lend itself well to camber changing. Perhaps the only mix desirable would be a reflex mode (like the 'invert' switch mentioned above) to dump lift from the wing and bring the plane down from altitude a little faster.

Winch, Highstart and Bungee Launching...

All our foamies with the exception of the 1-26 HLG can be winch, highstart or bungee launched. Even the 1-26 HLG can be highstarted on a lightweight highstart, but nothing of greater power.

The TG-3 in particular is suitable for winch launches and can be run up the winch line 'pedal to the metal'! The warbirds are also great fun to winch. Highstarts and bungees, made from lengths of surgical tubing, are no problem at all and are a very good option for solo flying or where quick setup of launch equipment is desired. Our TG-3 and foaMe163 models actually contain the towhook mounting plate and hook in the kits. The warbirds can easily be fitted with a 1/4 inch thick ply towhook plate at the bottom-front of the wing during construction (about 1 1/2 inch square) for fitting of a tow hook later.

Fore and aft positioning of the tow hook has a great bearing on the launch profile. For high, long launches the tow hook is best placed a little ahead of the C.G. This setup will have the plane leaving your hand at high speed and then almost immediately rotating to a vertical launch that begins to flatten toward the top, describing an arc around the highstart's stake or the winch's turnaround pulley. As the hook is moved more forward, it will tend to flatten the launch. With the hook just behind the leading edge of the wing, you'll get a very straight and level launch, and a slight pull of up elevator after release will shoot the plane up to considerable altitude.