Weight: 278 pounds including 24-pound parachute
Wingspan: 23;feet at leading edge, 25 feet at trailing edge
Wing chord: 78 inches
Dihedral angle: 5 degrees per wing
Wing to ground angle and incidence angle: 7 degrees,
no wing twist
Flaperon chord length: 16 inches with initial angle set at
16 degrees droop
Wing section: Upper surface is a modified NACA 23012/23013
airfoil. Bottom surface is flat and recessed toward the trail-
ing edge spar with concave deflections during aerodynamic
loading. The wing profile is maintained by internal wing
suction in flight.
Wing material: Removable Dacron, 4 ounces per 36-by-
28. 5 inch area
Stall speed: 26-27 mph
Top speed: 63 mph
Cruise speed: 30-50 mph
Cruise rpm: 4500 with fixed-pitch propeller, 3800 esti-
mated with in-flight adjustable-pitch propeller
Engine: Hirth 3203 with dual Dellorto carburetors
Horsepower: 65 6300 rpm
Reduction type: Cog belt with modified pulleys and eccen-
Cog belt reduction ratio: 2.6-to- 1
Propeller: Powerfin “F” two-blade with 70-inch diameter
Climb rate: 1,500 feet per minute with 180-pound test pilot
Takeo; ground roll time: 3 seconds with no wind;
Fuel capacity: 5 U. S. gallons
Full vehicle emergency recovery ballistic parachute:
Magnum ballistic parachute system 300 soft pack rated for
662 pounds at 138 mph. Deployment time estimated to be
2 - 2. 5 seconds.
Rims: Hegar #4 (modified for the 12-bolt Snedden;hubs on
0.750-inch diameter axles)
Tires: Nanco 4.00-6
All specifications listed are subject to change.;
PHOTOGRAPHY BY TIM GAFFNEY
Andrew concentrates on control inputs prior to takeo;.
is the engine of choice for high-power ultralight-type
vehicles. The engine is hung from a T-shaped
machined aluminum engine mount that permits
thrust line adjustment for engineering development.
A two-blade 70-inch diameter Powerfin Type F
ground-adjustable propeller is driven through a 2.6-
to- 1 cog belt reduction. (Hirth also o;ers a
gear-reduction unit with ratios ranging from 2.16-to- 1
to 3.51-to- 1.) At 6300 maximum engine rpm, the prop
turns just over 2400 rpm, giving a propeller tip speed
of 740 feet per second. Future production machines
are intended to remain in the ultralight category so
that an in-flight adjustable propeller can be used. ;e
Magnum full-plane parachute system will be standard.
;e 79-pound, German-made engine, imported
by Recreational Power Engineering of Ti;n, Ohio
( www.RecPower.com), is available in either forced-air
or free-air versions. ;e dual electronic ignition, two-cycle engine uses a pre-mix of oil and unleaded auto
gas. Engine displacement of 625 cubic centimeters is
split between the two Al-Nikasil lined inline cylinders
equipped with dual Dellorto 34-mm slide carburetors
and reed valve induction. A 108-pound, water-cooled,
three-cylinder, 100-hp Hirth 3701 high-performance
engine is being considered for ultralight floatplane
and other future applications.
;e Hirth engine and propeller speed reduction
unit (PSRU…aka belt reduction drive) has been modified to reduce weight. Drive pulleys have been drilled
for lightening holes. ;e bearing support plate has
been replaced with a lighter machined support.
Andrew designed and installed a lightweight cable
recoil start system to replace the electric starter, and
free air ducting was added. Exhaust modifications are
planned for further weight reduction.
A MAGIC CARPET RIDE/ When flight instructing, I
have often remarked to flight students, “Once you
learn how to get in to and out of the aircraft, the rest
of the flight will be easy.” ;is is especially true for the
Snedden M7. Its short wings each have two splays of
both leading and trailing edge flying and landing wires
for a total of eight wires per side. In addition, both the
landing gear and the inverted V-tail are wire-braced.
You enter and exit the plane from the front by crawling
over the front axle and entering the seat from below.
A video of this operation is posted on the website and
used for pilot training. ;e truss structure geometry,
short span, and generous wire bracing facilitates the
lightweight yet rigid airframe that is required for ultra-
light classification with the relatively large engine.
Grant Smith soloed a Cessna 140 in 1959 and retired
from United Airlines flying a 747 in 2003. He designed
and built hang gliders in the 1970s and is the Design Wing
Director for;Aero Sport Connection. He;is an active;flight in-
structor in many types of;ultralight, light sport, and general
aviation aircraft. To see a photo gallery, video, and read
more about the Snedden M7 visit www.SportAviation.org.