The Me 262 was the first operational turbojet powered aircraft. In addition
to being jet powered it had many advancements in aircraft design. It entered the
Second World War too late to be really effective, but still proved itself a
potent weapon.
Development began on the Me 262 in 1938. A combination of excellent design and,
some say, downright luck resulted in a very harmonious design which
significantly stretching the known aeronautical boundaries. An example of this
is the Me 262's wing. The characteristic swept design was the result of a need
to place the center of gravity aft to compensate for heavier then expected
engines. It was only later that the benefits of swept wings were appreciated.
The first test flights began in 1940. Since the planned turbojets were not ready a conventional twelve cylinder engine was mounted in the nose to test the airframe. Later when the BMW 003 engines were installed a test flight took place which resulted in both turbojets failing and the pilot bringing the plane in on the nose mounted engine alone. The aircraft became the first fully jet propelled aircraft in July, 1942.
The Jumo 004 engines were the Me 262's greatest weakness. Turbojet engines were still in there infancy and many technological hurdles had to be overcome. This resulted in a lengthy period of development which led to continued delay in the development and production of the Me 262. One of the problems was that the materials necessary for proper heat proofing were extremely rare in war-torn Germany. Alternate materials had to be used which resulted in engines that were unreliable. In some cases, a brand new engine would suffer catastrophic failure during initial run-up. All the engines had a very short operational life. Most would only last for 12 hours of operation. On many occasions, pilots were forced to land with one or both engines out.
John's has built 25% and 36% scale models of this aircraft. They are
both detailed on this page.
Beginning with the 25% models, shown in the picture above, it had a wingspan of 3.45m (136") and a dry weight of 42lbs. It was powered by two AMT Pegasus single stage gas turbine motors, each producing 23lbs of thrust at 105,000 rpm. Idle speed is 30,000 rpm and the motors run on 28SEC heating oil (kerosene). The model had a fuel capacity is 10 litres, sufficient for a 12 minute flight plus safety reserve.
Construction of the model was predominately balsawood with a complete monocoque fuselage glassed with epoxy resin inside and out. Wings and tail were traditional built-up, sheeted with balsawood and epoxy glass skinned. The model had a retracting undercarriage and wheel brakes. Substantial surface detail was added including rivets, panel lines and inspection hatches.
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The model was first flown in 1998. John has had amazingly bad luck with this model. He actually has built two. The first was destroyed after only a few flights due to a rare radio failure. However, it flew so well that another was built. This was also destroyed when it hit a bird during a flying display. Not to give up, John has now nearly completed another. The new one is even larger and is detailed on the rest of this page.
John, adds scale to his 25% scale model at Duxford.
Well, as it says above, John and the rest of the Ghost Squadron built another one at 36% scale size. It has a wingspan of 4.6m and its dry weight is 45kg. Its fuel capacity is 15 litres (3 Gallons). It is powered by two AMT Olympus turbines. It was completed ready test flying in December 2003.
John gives scale to the model in its ready for painting condition. This was the first time it had been properly assembled. (Duxford 2003)
Now completed, here is John assembling it.
After almost 2 years of designing and building, the
Messerschmitt ME 262 finally took to the skies on 5th February 2004 for its
first flights. Here is John's report of the model's first outing.
With the kind permission of the Swindon Model Aero Club and with special thanks
to Eddie Barker their secretary I was able to have the use of Wroughton Airfield
for the day. Thanks also go out to
LMA member Steve Holland who took a day off work to act as witness and cameraman
for the flights (don’t give up your day job Steve ). Of course my great friend
and fellow Ghost Squadron member Alan Carter was also on hand to assist.
Conditions on the airfield were not ideal with rain and a moderate wind.
We were all grateful for the protection afforded by the Ghost Squadron Motorhome
parked side on to the weather. The model was assembled in gaps between the rain
showers and then the tanks were filled-up with 15 litres of fuel ready for the
first flight.
The model had been taxied at both low and high speeds prior to the trip to
Wroughton so no problems were expected in that area so with a short break in the
rain it was time to go. Both AMT Olympus motors were started and the model
taxied out for take-off. A pause at the end of the runway for a final check and
the throttles were opened. The model quickly accelerated with impressive spray
as the wheels ran through the puddles on the runway and threw water up into the
jet exhaust. With no elevator input
the model rotated after approximately 80m and settled into a gentle climb.
Immediately undercarriage up was selected, but only the nose leg retracted. The
model was still accelerating hard so the throttles were reduced to less than
half and a first turn initiated. It was clear at this early stage that this
model flew just like the previous smaller ME 262’s I had built…It should do
as it is only a scaled-up version. By the time I was level with myself going
down wind I had realised that only one click of up trim had been applied and the
model was flying as if on rails even with the main undercarriage legs still
down. One further circuit confirmed my initial thoughts that the model was
exhibiting exactly the same characteristics as my previous models, i.e it flies
as if on rails and the pitch trim changes with throttle setting.
By the second circuit I felt completely at home with the model and
executed a slow roll right down the runway.
Next was the stall which was a complete non-event, the model just hanging
on the wind nose high before finally slipping gently off to the right as the
nose dropped. I was so pleased with the way it was flying that I next tried a
power-on downwind climbing stall. The previous models on approaching the
power-on stall pitched up at the last moment as the low thrust lines took over
and this could flip the model over onto its back or put it into a spin. On the
new model the pitch-up was there and the model gracefully flipped over in a sort
of flick roll and into a spin. Normal corrective action stopped the spin and the
flight continued. More rolls were next followed by a loop before Alan advised me
that I had been flying for 8 mins and it was time to land.
Undercarriage down was selected and to my horror as the noseleg extended the
main legs retracted!!!! A flip of
the retract switch had the noseleg retracting again and the mains extending. I
quick call to Eddie Barker to see if there was any good grass areas to land on
came back with the answer NO. This was confirmed by Steve who said the grass was
very rutted. I had to make a quick decision due to the diminishing fuel load and
elected to land on the runway which would of course grind away the underside of
the engine nacelles. An approach was made using full flap and the model held off
for as long as possible, the wheels touched and the nose dropped to the sound of
grinding balsa. The model was recovered and the motors shut down.
A check was made of the airframe and the damage only amounted to a small hole in
the bottom of each nacelle where the wood had worn through. A repair with some
Diamond tape was made by myself and Steve and with the agreement of all present
the model was declared airworthy to fly again.
The retract problem was traced to crossed pipes in the pneumatic system but no
one could work out why the noseleg had remained extended when the air system was
charged, it should have retracted when the air was put in. Several cycles of the
system proved all was well and after fuelling-up it was time to go again.
With the knowledge gained from the first take-off a small amount of up elevator
was applied during the take-off and rotation occurred after approximately 60 to
70m. Care was taken to remove the up as rotation occurred to avoid the low
thrust line pitch-up problem. Undercarriage up was selected and all three wheels
went away. Now it was time to enjoy. Loops, rolls, Farnborough passes and 90
degree bank reversals were all completed as well as some hovering in the wind as
the low speed end of the flight envelope was explored. With only a couple of
notches of power the model would happily sit stationary in the air and had to be
seriously provoked to stall. As the
fuel was burnt off and the weight reduced the vertical performance became
evident. Big climbs with rolls off the top were easy as was a full Cuban 8. On
exiting the Cuban 8 at about half throttle some minor flutter of the wings
occurred and the flight was immediately aborted. Retracts were selected down and
the flaps lowered to slow the model down. This time the noseleg extended only to
hang up on the door mechanism so not fully extending. Another landing without
the noseleg extended more damage was made to the sheeting on bottom of the
nacelles.
After shutting down the motors and draining the remaining fuel from the tanks
the model was disassembled piece by piece and each part checked for wear or
damage. Apart from the holes in the bottom of the nacelles the only problem was
a loose wing-mounting strap probably caused as a result of the flutter.
After a final discussion about the flights whilst sitting having a cup of tea in
the Ghost Squadron motorhome Steve was happy to sign off the two flights as
qualifying for the flight test log. Alan countersigned the log and a note was
included regarding the possible wing flutter.
On returning home this area of the wing was exposed and the screws holding the
plate were found to have pulled in the wood. This will be replaced with a bigger
plate and longer screws before the next flight. With regard to the possible
flutter, the mass balancing of the ailerons will be changed to alter their
resonance frequency by adding some lead to the leading edges.
Note – A further discussion with Steve and Alan after opening the wing
leads me to think that it was not flutter but a failure of the wing strap
causing the wing to flex. The reason for these thoughts is that the wing strap
was only pulled in one direction and not back and fourth as would be the case
with flutter. From the video shot by Steve, the wing can be seen to flex only 2
or 3 times at a slow speed whereas flutter normally produces a high speed
oscillation. Further support to this theory is the lack of damage to the aileron
servo gears or linkages. This is
only a theory, but mass balancing the ailerons will be carried out as a
precautionary measure before the next flight.
The process of balancing the ailerons began and it was found that 10ozs of lead
would be required for each aileron. This didn't seem sensible so completely new,
lighter, ailerons were built. These, with mass balancing, weigh 1 oz less than
the old ones.
On the third flight of the day another problem occured. The grub screws holding the fork to the noseleg came undone allowing the leg to rotate 90 degrees. The landing was going to be interesting! The plan was to hold it nose up as long as possible. Full flap and a lot of power achieved this. Kohn was amazed so see that a ridiculous angle of attack could be held with no problem. The bottom of thr rudder was almost dragging on the runway. Final touchdown resulted in no damage to the model, except the nacelles again! Three more flights were added to the test log and more wotk was done on the model.
On returning home the fork was welded to theleg and the bottom of the nacelles repaired. John had also felt the model was slightly nose heavy and so a pound of lead was removed form the nose.
Another flight with 5 percent less elevator and John was happy. He noticed that the size of a loop could be made appreciably larger as the fuel weight reduced. Another landing andf Tony Hopper was heppy to sign off the flight test log. The total test flight time had been well over an hour. Tony was happt to issue the paperwork for a full Exemption.
It has been interesting to note that although the model was sound little things
needed sorted and are there to catch the unwary. This is a main reason for the
flight testing. To get the bugs out of the model.
John wishes to thank Alan and Vic from the Ghost Squadron (his team), Tony
Hooper, Steve Holland, Richard Rawle, Eddie Barker and all those other people
who gave support and encouragement during the project. As always the membership
of the LMA are so impressive in their willingness to provide help and
assistance.
This page was last updated on 5/6/04.
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