Tales of a Fokker D.VII

Fred Berg P.O. Box 204

St. James, NY 11780

Fred Berg's pristine Fokker D.VII was scratch built over a five-year period beginning in 1963. Since completion it has acquired about 220 hours of flying time, and a very colorful history. Photo: Fred Berg Collection

Construction of the Fokker D.VII started in 1963. To be

honest, I did not know what was involved. Everything

on the plane is highly specialized. There are no “off-the-

shelf” parts. Everything must be handmade. There was

a war on in Vietnam, people were busy, and since the

Internet didn't exist, finding parts was difficult. Yes, the

plane flies beautifully, but it is not streamlined.

Aerodynamically, it is very dirty. Because of the high

drag it needs a ten foot diameter, slow-turning propeller,

and an engine to match. Remember that the thrust of a

propeller is proportional to the square of the diameter.

Double the diameter, and you increase the thrust four

times. Helicopters fly because they have big propellers.

Since the slow turning engines with proper horsepower

are water-cooled, the plane needs a radiator. These three

items (engine, propeller, and radiator) cost the builder

well over 1,500 hours in original construction time.

Two of these three items, the propeller and the engine,

caused three emergency landings. If you build a modern

plane, you don’t need a radiator, and the other two items

are store-bought and very reliable. Building this plane

was an 8,000 X 8,000 job…8,000 dollars and 8,000

hours. The plane exists because the builder was

compulsive and neurotic.

The Engine

The engine, a 160 hp Hall Scott M5A, was a basket case.

The carburetors, magnetos, one magneto bevel gear,

water, fuel and oil pumps were missing. The engine was

rebuilt. When the engine wouldn’t start, it was

discovered that it ran in the wrong direction. That meant

the propeller and accessories were useless. Therefore the

direction of rotation was reversed. The bevel gear on the

cam shaft that mates with the tower shaft gear was

turned around and placed on the other side of the tower

gear so that the camshaft now rotated in a proper four-

cycle order (Intake, Compression, Power, Exhaust). The

shaft had a large hole through it, which was bored out to

.750”. The shaft was cut into six pieces and reassembled

over a .750” steel tube. Since a six-cylinder engine turns

two revolutions to complete four cycles, a cylinder fires

every 120 degrees. The crankshaft throws are located

every 120 degrees. The camshaft rotates at half-

crankshaft speed, so that each set of cam lobes is located

at 60 degree intervals. The cylinder firing order is

1,5,3,6,2,4; therefore, the cylinder cam sets are set up 60

degrees apart in that order. When looking at the

camshaft, one would notice V notches in the center of

the long bearings. This is where the camshaft was

welded up. When completed, the engine ran fine.

Propeller

The propeller curves were taken from an original Fokker

D.VII located in Knowlton Quebec War Museum in

Canada. These people were extremely helpful and

permitted me to actually touch their plane. I had no

alternative but to carve the propeller myself. The

propeller is 10’-2” long and has a pitch of 68 inches.

The propeller was balanced on a large needle. It was

balanced in a longitudinal direction by sanding the heavy

side, and the final precision balance was achieved by

using varnish on the light side. In the transverse

direction, brass washers were placed in counter-bored

holes by the propeller bolts. The ash wood in the

propeller was wet, and there was a crack in the first layer

of ash. The propeller tip is about six inches from the

ground when the plane is horizontal to the ground and

will suck up stones when taking off at full throttle. That

is why propellers have copper tips to protect the wood.

Above & Top Right: Two views of the original Hall Scott M5A engine seen mounted in the fuselage of the author's Fokker D.VII. Six of these engines were manufactured in 1917, and they are almost exact copies of the Mercedes engine that powered many D.VII aircraft in World War I. Lower Right: The author's hand-carved, 10' 2" propeller, fashioned from lead templates which were fitted to an original Fokker D.VII Photos: Fred Berg Collection

Left: The author holding the welded steel tube fuselage. With a lack of original drawings to work from, the original Fokker D.VII owned by the Smithsonian Institution served as a source to obtain precise measurements. Fortunately, the aircraft was undergoing restoration at the time and was completely disassembled. Above: The framework of the rudder, horizontal stabilizer and elevator. Below: The author's Fokker D.VII coming together in a shop on Long Island's North Shore. Photos: Fred Berg Collection

The Radiator

The radiator is a required part that adds beauty and

character to the plane and must be as authentic as

possible. The radiator fits over the upper crankcase and

wraps around the first cylinder. The core consists of

5,000 tubes which are soldered together by hand. Each

tube is four inches long and the half-inch ends are

hexagonal in shape. The soldering takes place at the

hexed ends forming a very strong beehive-type structure.

Air flows through the tubes, and water surrounds the

tubes. The radiator holds an enormous amount of water

and is very efficient.

Richard Peterson

I first met Richard Peterson during the 1950s when he

owned a foreign motorcycle shop in Queens, NY, and

knew him to be a first-class metal worker. Our second

meeting took place in 1965, when I met him by accident

in a bar. At this point he was working for Grumman

Aircraft, and after I told him about my project, he agreed

to try to help me with the metal fabrication. It took only

30 minutes to explain what I needed and to draw up

some free-hand sketches. A month later he called me up

and said he needed more information. I went to meet

him and was stunned to see that all of the parts were

perfectly made. The radiator dome with its compound

curves, the lower part with its compound bends, and the

engine pan that meets the radiator were all coming

together with great precision. The parts were smooth as

glass, with no dents or forming cracks. Considering the

information that he was given and the time that he was

allowed, his performance was unbelievable. I don’t

know what I would have done without him.

Richard Peterson's beautiful work forming the radiator dome, as seen during various stages of construction. Photo: Fred Berg Collection

One of the hand soldered radiator tubes which needed to be replicated 5,000 times in order to produce the D.VII radiator.

Photos: Fred Berg Collection

All 5,000 radiator tubes awaiting installation.

Photos: Fred Berg Collection

The completed radiator seen mounted on the D.VII fuselage. Photo: Fred Berg Collection

First Emergency Landing

The first emergency landing occurred when a copper tip

broke loose, and the plane vibrated violently. The plane

landed in an isolated area to ascertain the problem.

Some men building a shopping store came over to join

the action. Four inches of copper tip were missing from

one side of the propeller, and the rivets shredded the

wood. Using the men’s tools, an equal amount was

removed from both sides of the propeller for rough

balance. An airplane such as this cannot be abandoned

even for one day in a field, so the D.VII was fired up and

flown back to its base of operation. Although there was

a slight vibration due to unbalance, the loss of eight

inches of the propeller length enabled the engine to turn

an additional 50 RPM. Afterwards, the copper was

removed and replaced with fiberglass. Then the propeller

was rebalanced.

The wayward propeller tip that was responsible for the first emergency landing. Photo: Fred Berg Collection

Second Emergency Landing

While flying near Riverhead, Long Island, the plane

suddenly started to kick, and I noticed that the exhaust

rocker on cylinder number one had cracked and was bent

out of shape, preventing the exhaust valve from opening.

When the intake valve opened, the burning gases went

into the intake manifold and disturbed the first three

cylinders. I had no choice but to land on a local farm.

The local farmers came out to investigate and brought

tools with them. Since the rockers and valves are

exposed for cooling and preflight oiling, they are easy to

remove. The intake and exhaust rockers were removed

so that nothing could enter or leave the cylinder. The

spark plugs were also removed so that there would be no

compression losses for that cylinder. The engine was

fired back up and ran very well. The loss of one cylinder

reduced the maximum RPM by only 50. And again,

since an airplane such as this cannot be abandoned even

for one day in a field, it was flown back to its hangar.

Amazingly, with no muffler and the exhaust pipe only

two feet from my right ear, I could still hear the loud

swishing sound generated by air roaring through the

empty spark plug holes. The exhaust rocker was

repaired. It seems that these large engines (over 1,000

cubic inches) are not finicky. Once they are running,

they keep on running. You would think that a dead

cylinder would cost the engine a loss of more than 50

RPM.

Third Emergency Landing

At 49 hours flight time, the propeller broke loose from

the plane and was never recovered. The propeller nut

did look very inadequate, but it fit the engine and

propeller hub and was not questioned. One would think

that losing the propeller would cause the engine to rev

up and explode because the load was removed from the

engine, but this isn't the case. The engine stops running

because the propeller is the flywheel and is necessary to

overcome the engine compression. This failure resulted

in a forced landing on William Floyd Parkway on Long

Island. The old saying that the most dangerous moment

of a landing is just before the plane comes to a stop is

true. That's because there is no airflow over the tail

surfaces to keep the tail down, and these types of planes

have a high center of gravity to keep the propeller blades

off the ground. This is especially true for the Fokker

D.VII. The center of the propeller is well over my head,

and I cannot reach the spark plugs without a chair or

ladder. At five miles per hour, I turned to roll off the

parkway into a field and thought I was safe. The plane

ran into a rut and very slowly, painfully tumbled over

onto its back. The tumble did seem to last forever. I

knew that I needed both hands to open the seat belt and

shoulder harness and that as soon as I did, I would fall

out of the plane and land on my head. I did just that.

Once again, an airplane such as this cannot be

abandoned even for one day in a field. It was

immediately dismantled and brought home. The college

had just received a Bridgeport true-trace milling

machine. This time, half of a propeller was carved, and

the true trace machine was used to copy the half proper

curves onto both sides of the new propeller blank.

Fabricating the second propeller took only a quarter of

the time of the first one. The propeller hub was another

story. It took forever to turn down 120 pounds of eight-

inch diameter steel to a final ten-pound hub with the

lathes available. This time, the propeller hub was made

to accommodate a real big propeller nut, one that would

never come loose again.

The author seated in the cockpit of the completed D.VII

Photo: Fred Berg Collection

The D.VII in flight. It was slightly overweight due to the addition of brakes, a tailwheel and a VHF radio which allowed it to land at modern airports, but it still performed extremely well. It had a top speed of 109 mph, a cruise speed of 95 mph, and could climb to 5,000 ft in six minutes.

Photo: Fred Berg Collection

Richard Flieg (The Dutchman)

Thomas Murphy, my flight instructor, introduced me to

Richard Flieg, a brilliant machinist who had a shop.

Tom referred to Richard as the Dutchman. Richard’s

formal education ended when he was about 13 years old,

a result of schools being bombed out during the war. He

spent his teens learning to be a machinist and working

long hours on the damaged railroads. After the war, an

American company in Germany hired him. Realizing

that he was an exceptional machinist, they brought him

over to America. (General DeGaul referred to this as the

American brain-drain of Europe). Now I needed a bevel

gear for my magneto. I tried everywhere to purchase

one. On two occasions machinists tried to make them

for me but were unsuccessful. The Dutchman came to

the rescue. He formed one side of simple 5/16 square

lathe tool to fit one side of the gear tooth profile, and

using a fly cutter and vertical milling machine, he made

the gear. The gear worked perfectly. The gear ran in the

engine for several hours and was then heat treated. The

Dutchman was the second person who willingly helped

me out. He taught me a lot about the art of machining

metal parts.

Thomas Murphy

Tom Murphy was an extraordinary pilot who gave flying

lessons until he died in his late eighties. As a youngster

he did stunt-flying and skywriting in addition to teaching

and playing the violin in a professional orchestra.

Although he was a natural to flight test the D.VII, he

was ill at the time, and it wasn't to be. The D.VII was

flown three times and ground looped on the second

landing. I was told that the reason the plane had such a

slow stall speed was due to a very light wing loading,

and that I should put skids on the ends of the lower

wings. This is the reason pipes appear on the lower

wingtips in some of the photos.

As the D.VII sat in a hangar at Grumman’s Calverton

field, it was being damaged, and I suspect that some of

the employees had a hand in this. When Tom was

available, I requested that he fly the plane to another

airport. He taxied the plane out of the hangar down the

runway and brought it back. I was shocked when he told

me that he would not fly it because it was not

controllable on the ground. There were two things

wrong with it.

1) Tom said that when the plane taxied, it waddled like a

drunk. It bounced, it rocked and rolled, and that was why

it ground looped. The landing gear springs had to be

tightened up substantially. The springs consist of three-

quarter inch bungee cords wrapped around the axle. He

demanded that I also remove the ridiculous wing tip

skids. I did all of this. When a plane is taxiing and leans

to the left, the left wing approaches the ground and the

right wing goes high. Under these circumstances, a gust

of wind under the right wing will cause it to go even

higher, thus pushing the lower wing into the Earth. This

is a ground loop. Many times a ground loop leads to a

plane further tumbling onto its nose, damaging the

propeller and motor.

2) He said that the rear tail wheel was not functioning

correctly. When taxiing, if you stepped on the rudder,

the wheel would not respond because the springs

connecting the rudder to the tail wheel were too soft.

They were replaced by considerably stronger springs.

Now everything was fine. It is amazing that a plane that

flies so well in the air could not fly because it was not

safe on the ground. After the changes were made, the

D.VII became a docile, fine-handling thing of beauty.

Thomas Murphy died when he was 88 years old, and he

is sorely missed.

Strange Stories

Heinrich Hoffman owned the original Competition

Motors in Smithtown on Terry Road. He was an

observer (beobachter) and all around mechanic in the

German WWI Air Force. Meeting me in a restaurant he

begged me to see the Fokker. The plane was completely

assembled outside my shop on Hollandia Horse farm in

Nissequogue. The shop was just over the top of a hill.

As we came over the crest of the hill he said, “Good

Lord, the wings are not parallel. Can’t you see that the

left wing tips are closer together than the right wing

tips?” He said that the left N strut between the wings

was about three centimeters shorter than the right strut. I

told him that he was crazy. In the front view the wings

are tapered in every direction. There is not a straight

line on the plane. The D.VII stands ten feet high with a

disturbing background of trees. How can this old goat

be so arrogantly certain about three centimeters? I got a

scale and made measurements, and damn it, the left end

strut was about 1-1/4” shorter than the right one (1” =

2.5 cm). Old Henry was correct. It really didn’t matter

because being off 1” over 22’ was insignificant and

would not affect the performance of the plane.

Hugo Mutz was a sergeant on the Suffolk County Police

Force. Once, while watching me work, he examined the

motor and said that something was wrong. He said that I

and O on the primer pump must mean input and output.

Well, the I line on the pump was going to the motor and

O line was to the fuel tank. He said “That’s wrong,”

then grabbed a wrench and reversed the lines. He solved

a problem before I knew I had one.

You must always have respect for all people because you

can never tell what their abilities are. Never put your

money where your mouth is, you may lose your shirt.

Sergeant Hugo Mutz is shown admiring one of the black German Spandau machine guns. Perhaps I can explain why he likes the gun. One day in full uniform during his lunch hour, he walked into a bank in Smithtown to cash his paycheck. He interrupts a holdup in progress, and the bandit panics and shoots Hugo seven times. Very angry, Sergeant Mutz returned the fire and ended the career of one bank bandit.

Photo: Fred Berg Collection

Summary

The Fokker D.VII has about 220 hours on it. The last

emergency landing occurred at 49 hours. After that

point in time, the plane had been perfected, no more

problems. Top speed is about 105 mph. The figure of

120 mph given in literature cannot be, for the plane

would be going faster than the propeller. The stall speed

is about 45 mph. The power on stall speed is much less

than 40 mph. That is why the allies in WWI complained

about the new German plane that can hang on the

propeller and shoot at you from below. Reihold Platz

was the designer of the Fokker D.VII and liked the big

hollow box spars because the spars produced wings that

were full cantilever. They did not need any bracing

wires between the wings. “N” shaped struts were placed

between the wings so that if one wing was damaged in

combat, the other wing would support it. Now thick

wings give tremendous lift, especially at low speeds.

This is why the plane has such remarkable flying

characteristics. I am not sure that all this was

understood at that point in time. When I lost the

propeller in flight, I was at an altitude of less than 1,000

feet. I flew over and followed William Floyd Parkway

in a northerly direction crossing Jericho Turnpike.

There was no traffic. Suddenly the four-lane parkway

divides into two lanes north and south with trees in the

divider. Two lanes produce a runway too narrow to land

on. Now I possibly have one-hundred and fifty feet of

altitude. I made a sharp turn going south over the

parkway and landed just short of Jericho Turnpike. All

this time I was gliding at 50 mph. After losing the

propeller, I felt like I must have traveled five miles.

How many airplanes can travel that slow and make sharp

turns safely? When the U.S. government gave Suffolk

County their military airport in the Hamptons, I was

invited to the celebration. Since I do not have radio

equipment in the plane, I contacted the tower and was

told that they would give me a green light when they

wanted me to land. Given the signal, I came into the

landing pattern, lined up with the runway and landed at a

nice, safe 50 mph. Everybody behind me cursed me out

because they had to go around the pattern a second time

because they couldn’t fly as slow as I could.

There is a drawback with the low stall speeds. If you

taxi fast with the tail down, there is a tendency to jump

into the air stalled, and then you can’t control the plane.

This occurs when the air flowing over the control

surfaces doesn't have enough pressure to make them

work. It's as if you were in a balloon. It happened to me

once. I drifted all over the place and just kept the nose

up, hanging on the propeller until I picked up speed and

could lower the nose. Once you have airspeed, you're

safe. It is a frightening experience. I know of two cases

where this happened, and the plane was lost. To take off

safely, get the tail up as fast as possible to kill the lift,

and when you hit 50 mph, the plane starts to float up into

the air and is very responsive to the controls. Again,

when landing at a slow speed, the ailerons in the upper

wing are not effective at all. If a gust of wind rolls the

plane, you must rely on rudder to straighten it out.

Simultaneously, give the engine more throttle and kick

the rudder on the side corresponding to the high wing.

The increased engine power will send a blast of air over

the rudder so that the rudder will respond. The plane

will yaw such that the high wing will move rearwards

and lose lift while the low wing will move forward and

gain lift. The lift is dependent on the relative airspeed

over the wings. When the lift is equal on both sides of

the wing, the wing will level off. Then kill the power

and proceed to land, or go around once again.

The last flight of the Fokker was at Oshkosh, Wisconsin,

in 1975. Teaching responsibilities and family problems

forced me to abandon the Fokker for what I thought

would be a short time. In 1976 my father died. I built a

house across the street from the farm so that my mother

could come live with me. I placed the Fokker in the

basement, where it remained until two years ago, when it

was purchased by Gerald Yagen for display at the

Military Aviation Museum located in Virginia Beach,

Virginia. Mr. Yagen plans to eventually restore the

D.VII to airworthy condition, and it will be permanently

housed at the museum in a new hangar dedicated to

World War I aviation, which will be erected in late 2009.

Everything said in this report is true. I hope you enjoyed

reading it and perhaps learned a thing or two.

Until we meet again, may God hold you in the palm of

his hand and keep you safe as he always did with me.

\

A sight which will hopefully return in the near future. Fred Berg's Fokker D.VII in flight. Photo: Fred Berg Collection

The Fokker D.VII photographed in 2007 at its new home: Gerald Yagen's Military Aviation Museum in Virgina Beach, Virginia. Mr. Yagen plans to eventually restore the aircraft to airworthy condition. Photo: Fred Berg Collection