Dyke Delta - Design

Design

The fuselage, wing spars and tail assembly are made from 4130 Chrome-moly steel tubing. The wing ribs are made from 0.019" steel channel along with 0.015" stainless steel formed from flat stock into a double-beaded "U" channel. The rib truss work is nickel-silver brazed together into ribs and onto the spars. The spar and ribs are a "Pratt Truss" design. The wing and fuselage skins are made of laminated fiberglas: 4-layers of 7½ ounce cloth and polyester resin. The skins end up around 0.065" to 0.070" thick and are held onto the ribs with 1/8" countersunk rivets.

The control surfaces and underside of the fuselage (center section) are covered with conventional aircraft (e.g. Dacron) fabric.

The upper fuselage/center section is the turtleback. It is formed as a fiberglass unit from hardboard ("Masonite") molds. Several variations have been created. The fuel tank is located in the turtledeck right behind the passenger compartment which violated FAR Part 23 standards for separating fuel tanks from passengers. Building fiberglass fuel tanks has caused problems because fuel additives or contaminants will degrade and dissolve the resin in the composite matrix.

The engine cowling is also made of fiberglass, laid in layers around a foam core. Once shaped, it is removed, the core stripped out and then other layers of fiberglass (stiffeners) are laminated in to strengthen the cowling.

The retractable landing gear (via levers and bellcranks) is made from 6150 steel, chosen for its strength and torsional properties. The gear assemblies are formed in the annealed condition to permit welding. Once assembled, it is heat treated. The retractable gear adds another 16 - 20 mph to the cruise speed along with decreased sink rate and a better rate of climb. The retraction sequence is very quick, lasting less than 5 seconds.

Construction time varies widely with builder commitment, skill sets, tools, access to metal forming equipment, etc. Some Deltas have been built under 2,000 man hours and under two years but six or eight years is more typical.

• Single engine in forward tractor position. Better than a rear engine (as in Long-EZ's) in a crash.
• No horizontal tail feature. No ability to increase lift factor with flaps and limited lift increase with angle of attack.
• Single full-time pilot because the controls are not duplicated to a side seat or rear seats. Not suitable for training. In an emergency others would have difficulty taking over pilot functions.
• Steel tube frame which is good for crash protection but the crash energy in the high speed emergency landings could easier overwhelm the structure. Strongly consider a BRS (Ballistic Recovery Chute).
• 3-place (although a 4th small passenger could fit in the middle of the rear bench, because of the other factors this is a higher risk aircraft for passengers).
• Higher cruise speed (~170 MPH) using a 180 HP Lycoming (at Gross Wt. () than most conventional aircraft of the same weight but slower than high performance aircraft of the same weight.
• Minimal CG changes due to the fuel and passenger load being centered on the main spar which is close behind the empty CG location.
• Low aspect ratio: the wing area divided by wing span (see span formula). This gives low drag but poor glide performance.
• Option to build folding wings/removable for storage in a single car garage or highway transport

The delta configuration offers a relatively high cruise speed compared to conventional aircraft of the same weight and power and a relatively high stall speed of 70 to 75 Mph. Approach speeds range from 110 to 100 mph with a flare at 70 mph.