[Back Cover]

[Front Cover]

Aircraft Construction and Aviation Commissioned by

The German Aviation Societies E.V.

Chapter 12

Gliding and Gliders by

F. Stamer and A. Lippisch Head of the Flying School

of the Research Institute of

the Rhön-Rossitten-Society e.V.

Head of the Technical Flight

Division of the Research Institute of

the Rhön-Rossitten-Society e.V.

Part II

Building Instructions and Drawings

with 8 illustrations and 5 plan sheets

Published by C. J. E. Volckmann and Sons, LLC

Berlin-Charlottenburg 2

Copyright 1927/28

Translated by James K. Hoffer

Table of Contents

Page

Aircraft Description . . . . . . . . . . . . . . . . . 5

Workplace and Materials . . . . . . . . . . . . . . 6

Building Instructions

1. Wing construction . . . . . . . . . . . . 7

2. Fuselage construction . . . . . . . . . . . 11

3. Construction of the empennage and

the control system . . . . . . . . . . . . 12

Final Assembly . . . . . . . . . . . . . . . . . . . 15

Parts Lists

1. Wing surfaces . . . . . . . . . . . . . . 17

2. Fuselage and tail boom . . . . . . . . . 18

3. Empennage . . . . . . . . . . . . . . . 19

Translator’s Postscript . . . . . . . . . . . . . . . 21

Construction Drawings Sheet

1. Assembly . . . . . . . . . . . . . . . . . 1

2. Wing with spars and hardware . . . . . . 2

3. Wing ribs . . . . . . . . . . . . . . . . . 3

3A. Rib verticals, diagonals, and gussets . . 3A

4. Fuselage with hardware . . . . . . . . . . 4

5. Horizontal and vertical tail sections . . . . 5

5

Aircraft Description

The “Sitzgleiter” [primary glider; literally “seat glider”]

depicted in the drawings is a braced monoplane consisting of the

following main parts:

right wing,

left wing,

support tower (cabane),

fuselage tail boom section,

tail surfaces (horizontal and vertical stabilizers),

rudder,

elevator,

control system.

It is shown in three principal views in the assembly drawing

[Sheet 1] and has the following dimensions:

length 5.3 m

height 2.0 m

wingspan 10 m

wing surface area ~15 m2

empty weight 65-70 kg

The aircraft is a training and practice glider designed in all

aspects for use by beginners.

The fuselage of the aircraft is built from sturdy wooden beams

reinforced on both sides with plywood sheeting.

The main controls and the hardware for the attachment and

bracing of the main wings are screwed onto the fuselage. In addition

to the controls, the pilot seat is located in the forward part of the

fuselage.

Four steel tubes that form two overlapping triangles having a

common base support the tailpieces of the aircraft.

The horizontal stabilizer forms the base that joins the tubing

triangles together. The vertical and horizontal stabilizers form a

rigid assembly to which the rudder and elevator are attached with

hinged bolts.

6

The wing uses the usual twin main spars and is internally braced

with guy-wires out to the flying wire brackets, while wooden

diagonal spars torsionally stiffen the unsupported outer sections.

The ribs are built up from capstrip spars and cross members, a

latticework supported by plywood gussets. Simple upright boards are

Figure 1.

Spar repair. (Gluing a doubly tapered board over the fracture on one

side accomplishes the repair.)

used for the main spars, mainly to provide the greatest possible

gluing surface for the eventual frequently needed repairs, Figure 1.

Workplace and Materials

Before beginning on such an aircraft, you must consider both

the workplace and the materials.

For the workplace, you should have an area of at least 6 m by

3.5 m with a height of 2.5 m.

Preferably, there is an exit leading directly to an outside open

area where you can assemble the aircraft. In any case, you should

verify that the door can accommodate assembled parts, such as the

fuselage assembly requiring a door height of 2.05 m.

The workplace should be equipped with a full complement of

cabinet-maker’s tools, such as a workbench, saws, a table saw,

planes, screw clamps, etc.

Now on to the materials.

One should realize that there are circumstances where one’s life

may depend on the quality of materials. Especially where aircraft

are concerned, the ‘best’ is just barely good enough. Due to the

7

necessity of saving weight, the materials are never thicker than

absolutely necessary and are highly stressed. Therefore

imperfections in materials can have dire consequences and much

care should be given to the selection process. Never let yourself

think, “This one will be good enough.”

For the wooden parts we use well-cured fir, with dead-straight

grain and no flaws. Southern German mountain fir is quite

acceptable.

Polish spruce also may be used for the main spars and the main

fuselage posts. With Polish spruce, it is easier to obtain the long

required lengths of blemish-free quality material.

The plywood indicated on the plan sheets is designated “birch

aircraft plywood,” available in the trade in all common thicknesses.

The various screws and bolts must be made from “SM-Stahl”

[stainless steel?]. Only metric threads are used. These screws and

bolts are found in the trade under “special aircraft screws.”

So-called “piano wire” is used for bracing, while braided steel

cable is used for the control connections.

The reader is referred to the advertisement sections [of this

booklet] for reference sources of the materials. All materials and

measurements are included in the parts lists.

Building Instructions

1. Wing Construction

Now we will begin the building phase, starting with the

construction of the wing.

After cutting out the wooden parts, build a jig for constructing

the ribs. Draw the full-scale rib profile on a flat board, along with

the positions of the upright and diagonal braces. Hammer in strong

nails such that the capstrips precisely follow the profile when laid

between the nails. Cut out the plywood gussets shown on the plans

as well as the upright and diagonal braces for all the ribs.

Now we can build the ribs, one after another, by spreading glue

on the plywood gussets, laying them down on the capstrips and

braces and securing them with flat-headed nails.

8

In this manner you assemble and glue each rib completely from

one side, then remove it from the jig and attach the plywood gussets

to the other side. Careful and accurate work is the order of the day.

It is simpler to assemble the type of ribs where the plywood

gussets lie between a double set of capstrips, because in this case the

work can be completed in the jig from just one side.

Figure 2.

Aileron diagonal braces and control horn installation.

There are four different kinds of ribs to be fabricated:

1. The ‘normal’ rib, wing part No. 2, made from a double set of

5 mm x 5 mm fir strips with 1.0 mm thick plywood gussets glued in-

between.

2. The normal aileron rib, wing part No. 2a, made in the same

way from 5 mm x 5 mm strips and 1 mm plywood, but having a slot

for the aileron spar. See Figure 2. The portion of the rib from the

rear spar slot forward is exactly the same as the normal rib 2. For

these ribs [2 and 2a] we use ~150 strips 5 mm x 5 mm x 1.6 m long.

3. The extra-thick rib, wing part No. 3, fabricated from 15 mm

x 5 mm strips with 1 mm plywood gussets on both sides. Because no

9

bracing diagonals or wires pass through these ribs, they have no

additional slots between the main spar slots. The layout is otherwise

the same as part 2. We will need eight of these ribs.

4. The extra-thick aileron rib, wing part No.3a, modified for the

aileron spar in the same way as 2a (two each).

For the thick ribs we need ~30 strips 5 mm x 15 mm x 1.6 m

long.

The main spars are then cut out exactly as shown in the drawing.

Figure 3a.

Forming the wire-eyes.

(Don’t forget to attach the spiral ferrule before bending the wire.)

Mark the position of each rib exactly on the spars and at this

time drill all the holes needed for attaching the hardware because this

will not be possible once the wing is assembled.

Lay both spars of one wing on a pair of sawhorses and slide on

the ribs in sequence, gluing them to the indicated positions. Then the

hardware can be attached. Square up the wing and install the guy-

wires for the internal bracing. Pay special attention to the form of

the wire-eyes. The formation of such a wire-eye is shown in figure

3a above. Don’t forget the ferrule for the wire-eye!

Be careful installing the wooden diagonals, parts 7 and 8, in the

outer wing section.

These diagonals run through the ribs, are anchored to them with

linen strips, and are attached to the spars with stout plywood gussets.

Counter-running strips of intersecting diagonals are given additional

10

anchoring at the middle. The inter-connection is accomplished with

plywood gussets glued in-between the strips because it is advisable

to use such a plywood connection wherever the wooden parts have

only a small gluing area. See Figure 4.

Slide the aileron spar into the ribs and glue the joints. 10 mm x

5 mm strips are added to the spar between each rib so that the height

of the spar matches the ribs. Install diagonal braces running from the

trailing edge, part No. 6, to both upper and lower sides of the aileron

spar. This scheme of triangular anti-torsion reinforcement is shown

Figure 3b.

Wire-eyes. (Bend with round-nose pliers, not with flat jaws.)

in figure 2. All the other control surfaces are built in this same

manner. The diagonal strips are anchored to the ribs where they

intersect with linen strips. Finally, the trailing edge strip, complete

with the plywood-reinforcing slat, is glued to the rear of the ribs [and

to the diagonals]. See Figure 2.

Before adding the plywood nose sheeting, it is necessary to add

filler strips to both top and bottom of the front spar because

otherwise the plywood will not lie flat along the spar between the

ribs. Use leftover 5 mm x 10 mm rib cap strip material laid

accurately between the ribs. Do the same to the rear spar only where

it is adjacent to the aileron spar. We have already equipped the

aileron spar with filler strips.

If we were to add filler strips to the inboard portion of the rear

main spar, kinks would occur in the covering due to the natural

tendency of the covering material to sag slightly between ribs.

11

Once everything is installed and the hardware has been

attached, the plywood nose sheeting and the planking at the first and

last rib are added. The plywood forces are carried by the extra-thick

ribs. Prior to gluing the plywood sheeting, dampen the outside of the

plywood with water to make it easier to bend. Dry plywood buckles

easily when bent.

Figure 4.

Diagonals in the outer wing panel and the aileron connection.

2. Fuselage Construction

Building the fuselage structure is simple. It is built right on the

workshop floor. Draw the exact outline of the structure and then nail

down a border of wooden blocks. Cut the main pieces to fit

accurately in this makeshift jig. As always, it is important to

accurately maintain the dimensions of the pieces. Wooden corner

blocks and plywood gussets are used to reinforce the corner joints.

The plywood on both sides of the fuselage assembly is 2.5 mm thick.

12

3. Construction of the Empennage and

the Control System

Building the tail surfaces requires 50 to 80 meters of 10 mm x

5 mm strip material for the ribs and diagonals. The eight ribs for the

horizontal stabilizer and the end pieces for the elevator halves are

built in a jig.

Figure 5a.

Control horn. (The spar fits through a notch in the control horn and

is anchored with a corner block on one side.)

Pay careful attention to the details in the drawing and follow

them precisely when preparing the double middle ribs.

The spars for the horizontal tail are again simple upright boards

(60 mm x 10 mm).

The rudder spar is a one-sided “ ”- spar, consisting of two

strips 9 mm x 10 mm and a 1 mm-thick plywood web.

Blocks and posts are glued in at the appropriate points to

reinforce the ribs and the control horns. Tips are made from 30 mm

x 40 mm strips, joined to the ends of the spars with plywood gussets.

Additional 20 mm wide blocks are glued in at these corners to

strengthen the ends of the spars where the bracing hardware is

screwed in.

The fin is built directly on the horizontal stabilizer. The fin spar

sits on top of the horizontal stabilizer spar and is connected to the

horizontal stabilizer at the front side with a block running through it

(50 mm x 10 mm x 200 mm) and at the rear with 1 mm plywood.

The leading edge is joined to the front spar of the horizontal

stabilizer by plywood angle gussets glued on the sides. A solid

wooden block connects the leading edge of the fin with the fin spar.

13

In the same manner as in the ailerons, triangular diagonal braces

reinforce the elevator and the rudder. The control surfaces are

hinged with the so-called ‘fork and eye’ bolts or small sheet-metal

hardware (see Chapter 11 of this series).

Figure 5b.

Control horn construction in the aileron.

The flying wires shown in the drawing reinforce the horizontal

stabilizer, primarily against landing jolts.

The fin is extended rearwards 30 mm by two plywood side

webs into which blocks are glued at the positions where the hinges

are attached. This extension allows the nearby rudder spar to swing

freely to either side.

The rudder horn fits around the spar and tight-fitting triangular

blocks add extra reinforcement to the connection. Refer to figures 5a

and 5b.

The empennage is suspended from the fuselage by four tubular

steel posts (30 mm O.D. x 0.8 mm wall thickness). The tubes are

flattened at the attachment points, the mating edges welded together,

and holes drilled for the attachment bolts. The upper supports are cut

14

off square at the rear ends and the lower supports lie with their

flattened ends under the upper ones. Drill several vertical holes

Figure 6. Mounting the wing

1 cm apart through the rear end of the upper supports to allow for

adjustment of the tail structure. The two sets of brackets built into

the horizontal stabilizer cradle the upper tubes from the sides and

connect to them with vertical bolts.

15

The steering structure is built up from steel tubing 30 mm x

1 mm wall. The control stick brackets and the aileron rocker-arm are

hard-soldered onto the roll tube. It is preferable to have these parts

prepared by an experienced welder.

The steering control cable pulleys and associated hardware are

available in the trade. The pulley blocks must be of high precision,

with rollers running freely, yet fitting tightly enough that the cable

cannot fall off.

Final Assembly

It is best to first assemble the aircraft before the covering is

applied, using the following steps.

Figure 7. Hardware bracket

Stand the cabane upright and attach the wings at the connecting

brackets (Figure 6a).

Add the four upper spar landing wires and tighten just enough

to give the wing a slight upward V-form (Figure 6b).

The ten turnbuckles, each having one forked end, are attached

directly to the spar hardware.

Now attach the lower flying wires and tighten until the wing

again lies flat (Figure 6c).

The rear lower spar bracket holds two wires attached as shown

in figure 7.

With the stabilizers already attached, hang the tail posts on the

fuselage and tension the structure with some 1.5 mm wire running

from the horizontal stabilizer rear spar brackets to the wing rear spar

brackets. There is nothing especially difficult about running the

aileron control cables (see the sketch in figure 8).

16

The aileron cables running from the rocker arms soldered onto

the torque tube to the double roller on the cabane are arranged so that

the cable coming from the right arm goes to the lower arm of the left

aileron control horn and vise-versa. The cable that joins the upper

arms of the aileron horns runs through a hole in the cabane. A

turnbuckle is spliced into the cable just off center in the right wing,

completing the loop and allowing for the proper centering of the

ailerons, both of which should lie exactly in the profile.

Figure 8. Aileron control cable scheme.

(See the fuselage assembly drawing for the elevator scheme).

Each steering cable under tension contains a turnbuckle for

adjustment. The sizes of all required turnbuckles appear in the parts

lists.

The application of the covering, etc., will not be discussed here.

You will need 45-50 m of material. Shirt linen, broadcloth, or

Cretonne (cotton drapery). Muslin is not suitable. The length given

above refers to the normal material width of 0.80 m.

If you desire to fire proof the covering material with waterglass

[sodium silicate], then you must use Cretonne because the other

materials will not shrink tight when waterglass is used.

Balance the aircraft accurately before the first flight (see the

section on aerodynamic calculations in Chapter 11).

For the first flight attempt, go to a flat area where you can carry

out hops of 100 to 150 m at low altitudes. Before flying, check the

flying wires and the action of the steering, especially whether the

direction of the control stick results in the correct motion of the

ailerons. It is easy to get the aileron controls reversed!

17

No. Name # Material Length Remark

1 Main spar 4 Spruce/Fir 90 x 12 4960

2 Normal rib 14 Fir 5 x 5 1500 1 mm plywood

2a " " (mod) 8 Fir 5 x 5 1500 1 mm "

3 Thick rib 8 Fir 15 x 5 1500 1 mm "

3a " " (mod) 2 Fir 15 x 5 1500 1 mm "

4 Wingtip 2 Fir 20 x 20 972

5 Aileron spar 2 Spruce/Fir 84 x 10 1913

6 Trailing edge 2 Fir 10 x 10 4600 1 mm plywood

7 Diagonal brace 2 Fir 10 x 10 1290 1 mm "

7a " " 2 Fir 10 x 10 1290 1 mm "

8 " " 2 Fir 10 x 10 1290 1 mm "

8a " " 2 Fir 10 x 10 1290 1 mm "

9 Ailieron horn 2 Fir 85 x 10 230 2 mm "

Aileron diagonal 4 Fir 10 x 10 793 to fit

" " 2 Fir 10 x 10 588.5 to fit

Leading edge sheeting 1 mm plywood

10 Tension wire bracket 8 Steel plate 15 x 1.5 85 5.2 mm hole

11 " " " 6 Steel plate 15 x 1.5 45 5.2 mm "

12 Wing bracing bracket assembly, 4 ea.

12a 8 Steel plate 1 mm thick

12b 4 Steel plate 1.5 mm thick

12c 4 Steel plate 2 mm thick

12d 4 Steel plate 2 mm thick

13 Wing-fuselage attachment assembly, 4 ea.

13e Spar bracket 8 Steel plate 2 mm thick

13f Fuselage bracket 4 Steel plate 2 mm thick

14a Pulley bracket 4 Steel plate 1 x 20 300 add 5.2 mm hole

14b Pulley 4 Aluminum 10 x 50 ∅ with bearing

Control cable Steel 7 x .25 ∅ 40 meter

Turnbuckle (wing bracing) 12 5 mm ∅ 70 Commercially available

Turnbuckle (cabling) 1 5 mm ∅ 71 Commercially available

Aileron hinges 6 Fork & Eye, See Part I

Cotter pin bolt 20 St. Steel 5 mm ∅ 15 with hole

Hex head bolt 8 St. Steel 8 mm ∅ 30 Metric thread

" " " 50 St. Steel 5 mm ∅ 30 Metric thread

Flying-wire (external) Music wire 2.5 mm ∅ Add ferrules

Guy-wire (internal) Music wire 1.5 mm ∅ Add ferrules

Cross Section

Parts List for

SitzgleiterWing

18

No. Name # Material Length Remark

1 Fuselage frame (heavy) 1 Spruce/Fir 70 x 35 8500 Gussets: 2.5 mm ply

Fuselage frame (light) " 35 x 35 7000 Sheeted w/ 2.5 mm ply

2 Tail boom assembly 1 Steel tubing 30 x 0.8 11800

2a Upper tubes 2 " 30 x 0.8 3300

2b Lower tubes 2 " 30 x 0.8 2600

3 Steering column 1 30 x 1

roll tube 1 " 30 x 1 1050

aileron tube 1 " 15 x 1 250

yoke 1 Steel plate 280 x 90 2

3a Rudder pedal bar 1 Oak 25 x 50 500

4 Tow hook 1 Steel plate 60 x 140 3

5a Pulley block 1 "

5b Double pulley block 1 "

6 Pulley shackle 2 "

7 Double pulley block 1 " 80 x 1.5 80

8a Lower flying wire bracket 2 " 40 x 1.5 210 5.2 mm hole

8b " " " " 2 " 40 x 1.5 210 5.2 mm "

9 Upper flying wire bracket 1 " 70 x 1.5 90

10 Wing coupling 4 "

11 Steering column straps 2 " 20 x 1.5 360

Control cable pulley 7 Aluminum 10 x 50 ∅ with bearing

Hex head bolt 30 St. Steel 5.2 mm ∅ 50 Metric thread

Turnbuckle (flying wires) 10 5 mm ∅ 70 Commercially available

Turnbuckle (empennage) 2 5 mm ∅ 70 Commercially available

Turnbuckle (cabling) 8 5 mm ∅ 71 Commercially available

Cross Section

Parts List for

SitzgleiterFuselage and tail booms

19

No. Name # Material Length Remark

1 Hor. stab. front spar 1 Spruce/Fir 60 x 10 1960

2 Hor. stab. rear spar 1 " 60 x 10 2500

3 Elevator spar 2 " 9 x 10 2500 1 mm plywood

4 Hor. stab. trailing edge 2 Fir 10 x 10 950 " " "

4 Rudder trailing edge 1 " 10 x 10 1250 " " "

5 Hor. stab. rib 8 " 10 x 5 620 " " "

6 Diagonal 2 " 10 x 10 1090 " " "

7 Hor. stab. tip rib 2 " 30 x 15 750

8 Elevator rib 6 " 10 x 5 380 1 mm plywood

9 Elevator corner support 4 " 10 x 10 490 " " "

10 Elevator diagonal 2 " 10 x 10 690 " " "

11 Elevator tip rib 2 " 30 x 10 400

12 Elevator horn 2 " 2 mm plywood

Hinged coupling 4 St. Steel Commerically available

13 Large bracket 4 Steel plate 20 x 1.5 140 5.2 ∅ hole

14 Small bracket 4 " 20 x 1.5 100 5.2 ∅ "

15 Leading edge 1 Fir 15 x 15 950 & 850

16 Fin spar 1 " 50 x 10 1200 Spdruce

17 Fin rib 4 " 10 x 5 1 mm plywood

18 Rudder spar 1 " 50 x 10 1500 Spruce

19 Rudder rib 6 " 10 x 5 480 1 mm plywood

20 Rudder corner suport 2 " 10 x 10 540 " " "

21 Rudder diagonal 2 " 10 x 60 680 " " "

22 Rudder horn 1 " 2 " "

Hinged coupling 3 St. Steel Commerically available

23 Tension wire bracket 2 Steel plate 20 x 1.5 100 5.2 ∅ hole

Turnbuckle 4 5 mm ∅ 50 Commercially available

Hex-head bolt 12 St. Steel 5 mm ∅ 60 Metric threads

Hex-head bolt 4 5 mm ∅ 15 " "

Cotter-pin bolt 4 " 5 mm ∅ 15 With hole

Guy-wire ( V. to H. stab) 4 Piano wire 1.5 mm ∅ 5000 Add spiral ferrules

Guy-wire (to wing) 2 Piano wire 1.5 mm ∅ 6250 Add spiral ferrules

Cross Section

Parts List for

SitzgleiterEmpennage

20

21

Translator’s Postscript

The photographs from this booklet did not photo-copy well from the

original. Making things worse, my JPEG copies are the result of a

second scan using my home printer. Therefore, the originals have

been replaced with digital photos of my 40%-scale replica of the

“Sitzgleiter.” Figure 2 is the clearest of the original photos, and

surprisingly, it shows some differences between the drawing sheets.

Because my model faithfully follows the Sitzgleiter drawing sheets,

it therefore shows the same differences. I have identified at least 5:

Figure 2 (original).

1). The support gusset surrounding the aileron horn is not a

triangle, as it is in Sheet No. 2.

2). The inboard diagonal brace in the aileron runs from the

inboard aileron end rib at the trailing edge to the next rib at the

aileron spar. But Sheet No. 2 shows the diagonal running the other

way, i.e., from the inner end rib at the spar to the next rib at the

trailing edge. Most of the photographs I have seen of the Stamer-

22

Lippisch ‘Zögling’ of 1926 (with an open, wooden fuselage) show

the first aileron diagonal running in this fashion.

3). The diagonal braces within the ribs themselves run opposite

to that shown in the plans on Sheet No.3. This includes the rib

diagonals in the aileron portion of the ribs.

4). As will be more apparent in the following figures, the extra

thick ribs have more uprights and hence shorter diagonals than

shown in Sheet No. 3.

5). The diagonal spars in the outer wing panel have slotted

webs, unlike that shown on Sheet No. 2.

― are there more?

Until I had finally finished the scale model wings and taken the

photographs to match the original points of view, only the first of

these five variances was obvious to me. My guess is that the wing

originally photographed was one from a 1926 Zögling that was

handy in the shop, but it was not the wing intended for this aircraft.

The original Figure 4, shown here, was difficult to decipher:

Figure 4 (original).

23

Of course, a great deal of this ambiguity is due to the fact that my

photo-copy of the original document was not of sufficiently high

resolution. But then, the original was not that clear either. This

photo does clearly show how the extra-thick ribs differ in having

more frequent uprights and shorter, more upright diagonals.

The original Figure 5b was much simpler, as seen here:

Figure 5b (original).

The five-sided shape of the plywood gusset around the aileron horn

is quite apparent. Another difference that can be detected here are

the gussets that support the aileron rib-to-spar junctions. They

appear to be more tapered than shown in Sheet No. 2.

In the German Virtual Aviation Museum you will find a side-view of

the “Stamer-Lippisch Zögling:” Compared to Sheet No. 1, there is

no obvious difference. However, Stamer and Lippisch themselves

never refer to the ‘Sitzgleiter’ as a “Zögling.” That name was

reserved for the earlier aircraft with a wooden, open-frame fuselage.

24

In his speech* delivered to the British Royal Aeronautical Society in

1931 entitled “The Development, Design, and Construction of

Gliders and Sailplanes”, Lippisch notes the following: “From

experience with the “Pegasus”, the “Zögling” (Beginner) was

developed, and as a further continuation of this series, the Stamer-

Lippisch glider, known in England as the “R. F. D. Dagling.” Martin

Simon reports† that he, along with many of his countrymen, learned

to fly in a “Dagling.”

http://www.luftfahrtmuseum.com/htmd/dtf/slzgl.htm

The 1929 manuscript How to Build…and…Fly Gliders‡ has several

photographs of a Sitzgleiter, including two of the wing ribs hung on

a fence. This shows that the Stamer-Lippisch pamphlets also made

their way to the States where a copy of the Sitzgleiter was built.

Following a visit to Holland by Lippisch in 1929, an aircraft nearly

identical to the Sitzgleiter was built in 1930 by Pander and Son. In

fact, it was the first aircraft built in Holland in 1930 and, using the

newly introduced international registration number system, it was

given the unique number: “PH-1”. A replica hangs in the

Aviodrome, the Dutch National Aviation Theme Park near Lelystad

Airport, the Netherlands. The museum note on this aircraft identifies

it as a Stamer-Lippisch Zögling Z-12, but I have not been able to

confirm this classification. Simons also noted that the Sitzgleiter

* Journal of the Aeronautical Society, p. 546, 1931(?). † Martin Simons, Sailplanes, 1920-1945, EQUP, p. 47, 2001 (ISBN 3-

9806773-4-6. ‡ Popular Book Corporation, 96-98 Park Place, New York, New York,

1929, see p. 13 for pictures of both types of ribs and p. 39 for a photograph

of the tail of a ‘Sitzgleiter” with a truncated rudder.

25

was produced in Switzerland by the Karpf Co. and sold as the “Karpf

Zögling.” It appears to be the same as the Sitzgleiter but with an

enclosed fuselage.

Although Simons credits§ Wolf Hirth with the development of

Zögling-like plans incorporating steel tubes for the rear fuselage, this

is clearly not warranted. In fact, the usage of four steel tubes

(forming two overlapping triangles whose common base is the main

spar of the horizontal stabilizer) pre-dates the present Sitzgleiter. In

1923-24, Lippisch, with the aid of the Steinmann Co., a

manufacturer of engine chains, built a school-glider called the

“Baby”. It became known as the Steinmann-Flugzeugbau ‘Baby’.

As can be seen from the following 3-view sketch from the memoirs

of Lippisch**, it also has the tubular-triangular rear-fuselage

arrangement.

Lippisch “Baby” (Steinmann-Flugzeugbau, 1924) ††.

If we credit the original design of this type of rear fuselage to any

specific person, it should be Lippisch. However, during the annual

§ Ibid, p. 44. ** A. M. Lippisch, Erinnerungen, Steinebach: A. Zuerl, 1980, pp. 78-83. †† The numbers are very difficult to read, but this aircraft appears to have a

wingspan of ~9 meters.

26

glider competitions at the Wasserkuppe that began in 1920, many

aircraft were entered that had steel tubing in the fuselage structure.

Perhaps this arrangement had been developed prior to 1923.

The original first-edition pamphlet was obtained from the U. S. Air

Force Academy Cadet Library‡‡, again with the superb help of the

Interlibrary Loan Department of the Los Alamos Public Library.

The value of this pamphlet to modelers such as myself is

immeasurably enhanced by the inclusion of detailed scaled

construction drawings. I had not expected this chapter to contain any

drawings at all because the lists found in previous chapters of

Flugzeugbau und Luftfarht [see the outside back cover, found at the

front of this translation] referred not to drawings, but to ‘Taflen’

[tables]. But, lo and behold, still attached to the rear of the booklet

were the five construction drawings sheets. They were brittle but

otherwise in perfect condition with absolutely no additional

markings. My impression was that they had never been opened!!

They were too large and fragile to copy in the library, so with the

permission of the Los Alamos Library I took them to a print shop in

Santa Fe where there was a flat-bed scanner large enough to

accommodate the sheets. They were not separated from the

pamphlet, but were unfolded and then protected by a large, clear

plastic cover sheet to avoid any damage while scanning. The

scanned TIFF files were ‘cleaned up’ using Adobe PhotoShop and

then used to make scalable AutoCad 2004 drawings. Later, I made

JPEG versions to include them here. In the JPEG’s, I have erased the

original German text and replaced it with English. The errors that I

have found in the drawings and in the parts lists are noted by a red X,

with my corrections adjacent.

‡‡ The USAF Cadet Library reference numbers for this volume are:

TLC 112, S78, v.2. A bar code was also added: 3 9333 00960001 6.

Unfortunately, the USAF Cadet Library has not allowed me any further

inter-library loans of the rare German booklets in their collection.

6

James K. Hoffer

Los Alamos, New Mexico

April, 2010

(not to scale)

(not to scale)

(not to scale)

1032

98

1146

930

1002

91.094.4

189.6

53.3

53.3

199.7

152.0179.9

156.6

93.8105.9

85.094.4

53.3

91.094.4

150.0154.7180.3179.3156.6

105.993.8

232.5 334.6322.3

170.8

199.7

310.8

310.6220.6

189.6

1007

1002

992

1490

1500

R25

680

675

651

646

382

377

353

348

1176

977

972

960668

370196

73

68

56

1468

1432

1171955

66351

365191

30

2222

2222

2222

20

20 12

2222

20

20

42

42

42

42

42

42

42

Sheet 3A. Wing rib verticals, diagonals, and gussets.§§

§§ Cryoflyer’s note: This was not one of the original drawings, but was prepared by the translator to facilitate the building of the wing ribs. The numbers adjacent to the verticals

and diagonals refer to the total lengths of each piece, i.e., from tip to tip. Numbers adjacent to the gussets give the total pieces needed. All data refers to full scale in millimeters.

(not to scale)

(not to scale)