Design Improvements for the Zenith 601 HDS

Design Improvements for the Zenith 601 HDS

The design improvements described below date from the 1990s and early 2000s.
For later changes, go to our website Points for Pilots.

Important Note

This page and additional links describe design improvements of the Zenith 601 HDS implemented in our plane N314LB. Anyone using the information does so at his/her own discretion and risk, and no responsibility or liability is expressed or implied. Bottom line, we are responsible for nothing.


Mel Asberry (expert builder, EAA Flight Advisor and prize-winning Technical Advisor, Designated Airworthiness Representative) and I (Klaus Truemper, novice builder and owner of N314LB) built the plane from a Zenith kit. Several minor design changes were made during construction. During the period 1995-2004, I made additional design changes, including a new engine cowl, mounting of radiator inside cowl, and wing root fairings. Lester Palmer provided expert assistance for the fiberglass work involved in some of the latter changes.


Completed December 1995. Empty weight: 636 lbs. Gross weight: 1,200 lbs. Engine: Rotax 912UL. Propeller: Sensenich 2-blade composite. It is pitched so that the engine achieves 5,500 rpm with full throttle at 3,000 ft MSL. This corresponds to a climb pitch, selected for maximum takeoff and climb performance at high density altitude since we often fly in the western states; for related computations, see Points for Pilots: Mountain Flying. Center tank (8.5 gal) and two tanks (6.5 gal each) in wing lockers have 21.5 gal total capacity. Note: The newer Zenith 601 HDS design uses two leading-edge tanks instead of the three-tank design.

Endurance and Cruise Speed: At 4,800 rpm and 3,000 ft altitude, endurance is 5.4 hrs @4.0 gal/hr and speed is 100 KTAS @ 900 lbs total weight and 95 KTAS @ 1050 lbs total weight.

Power-off stall @ 1,020 lbs is 42 KIAS. Power-off best glide @ 1,020 lbs is 65 KIAS with 650 ft/min sink rate, which corresponds to a glide ratio of 10:1. Ceiling @ 1,100 lbs total weight is 15,000 ft density altitude. Minimum rpm to stay aloft @ 850 lbs total weight and 3,000 ft density altitude is 3,600 rpm, producing 54 KIAS. Maximum speed at 5,400 rpm is 115 kts for 900 lbs total weight and 112 kts for 1050 lbs total weight.

TTAE (Total time Aircraft & Engine) (October 2019): 2,000 hrs.

    Details of Changes

  1. Cockpit
  2. Engine and Propeller
  3. Engine Cowl
  4. Main Gear
  5. Nose Gear
  6. Tanks
  7. Rudder
  8. Wheels
  9. Wings