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Author Topic: Memories of a speed plane in 1947 - 1949  (Read 904 times)
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bertcarr
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« on: October 26, 2011, 07:54:20 AM »

                          Recollections of a U control speed flight in 1947 – 1949.


The speed airplane that I built was a copy of speed planes that I had seen pictures of. The speed class was “B” up to .029 cubic inches. My engine was a McCoy 29 petrol spark ignition engine which I ran as a glo plug engine. This engine was rated at 0.54HP at 14500RPM. I did not experience any difficulty running this engine on methyl alcohol castor oil mix.
 The engine had been modified by skimming the cylinder head by 0.03125”. The vertical port pillars of the transfer and exhaust ports were filed to increase the cross section area. The height of the ports was left alone. The cooling fins were filed down to decrease the width of the engine to fit into a narrower cowl. The cylinder head screws were used to judge the max amount to be taken off... The big end was bushed with lead bronze so as to increase the con rod length. This increase in length was then used in reducing the piston weight as well as changing the shape of the deflector to fit the cylinder head shape. The piston top was polished as well.

Description of the speed plane as best I can remember.

Wing: 12 or 13 inch
Chord: 1 ¾ down to 1 inch at the tip.
Fuse: Max diameter as wide as the engine bearers tapering forward to suit the spinner and backwards to about ½” split on the thrust line. If I remember correctly the fuse was about 15” long. The engine was completely coweled in with air slit fore and aft.
Stab: About 6 x 1 1/4” Control surface about 3/8” wide.
The painting was a long protracted process as anybody who has doped balsa will know. I can only remember my fingers bleeding from sanding down between the many coats.
I always painted my airplane red and yellow using fuel proof enamel. The trade name of this paint escapes me.
The control wires were imbedded in the wing and the bell crank was mounted directly on to the wing.
The inside of the fuse was hollowed out to make space for the fuel tank and controls. The engine bearers were fitted into cutouts on the bottom half of the fuse and went from the front to just aft of the wing.
The fuel tank was made using brass shim stock about 0.010” thick. The filler and overflow pipes were positioned as for all control line planes in those days.

A competition flight as I can remember.

Roll out the wires and connect to plane and control handle. Fit new propeller to the engine.
Now the pull test which was done by the safety person. I do not remember the pull test details.
Mix fresh fuel three to one methanol and castor oil.

Fill the tank. We used oil cans that pumped the fuel with all metal pump parts. The plastic oil cans were destroyed by the methanol. Squeeze bottles were not yet thought of.

Test glow plug by connecting the starting battery and looking into the exhaust. We ran open exhaust in those days.

Start the engine by hand. Very few people had starters. Those that had made them using a car starter which had a rubber tube that could engage the prop spinner attached.

The McCoy always started without any problems. My helper would then adjust the needle valve while I went to the center. He would then at my signal run and hand launch the plane.

The launch speed would never be fast enough for a simple transition to flight. The plane would loose height as it tried to pick up flying speed. The engine was running very fast as the prop was struggling to get hold of the air.
Downwind. The plane would loose height needing a lot of up to prevent contact with the ground. Into the wind the plane would climb, a bit of down so as not to loose too much speed. The next laps would be a bit better until the prop started to bite. You could feel the vibrations down the wires and one could hear the engine take the load as it all started to come together.
Now I can stop walking around the pylon helping the plane by leading with the wires and take my place at the pylon as required before signaling to the timers.
By this time the engine has reached its max revs and all one could do is to keep the plane at a steady height until the fuel ran out. It was possible to judge if the prop was working properly. Revs to low, pitch to high blade width to wide or blade pitch not equal.
The next trick is to land without busting the prop so as to be able to improve it was always a problem having to fly with an untried prop each flight.

What I would like to convey is the total connection between the pilot and the plane during the flight through the sound of the engine and the feel of the airplane down the wires. I can’t think that there is that type of connection flying any other type of model.

I used to carve my propellers as the price was out of my reach. I used to use old hammer handles for the blanks as I was told that the wood was Hickory and that it was very strong. I have racked my brains trying to remember the size and pitch that I used maybe 5 x 9” or so. We also tried single bladed propellers but the balancing proved to be too difficult. Other than that the single bladed props worked well although I never got one of them to a timed flight.

At that time my best speed using this engine was 102 MPH.

Bert
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greggles47
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« Reply #1 on: October 31, 2011, 07:05:21 AM »

That's absolutely great Bert. Thanks for your very clear insight into running speed in those days.
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wreckbender
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« Reply #2 on: October 31, 2011, 11:09:37 AM »

Yes, thanks Bert. Nice to read your story. But I think you´re wrong about that you cant feel other types of planes, when i fly my stunters get I connected with them Smiley
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Don McLellan
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« Reply #3 on: October 31, 2011, 01:14:30 PM »

Great story Bert.  Thanks for sharing.

Don
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gossie
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« Reply #4 on: October 31, 2011, 05:33:55 PM »

Great story indeed.  I liked it. Smiley
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bertcarr
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« Reply #5 on: November 02, 2011, 04:54:03 AM »

Thanks for the comments you guys,
When I said that you did not have the connection to the plane in other types of flying i was thinking of free flight, RC etc.
I can remember the connection to my plane while flying stunt as well.

Bert
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« Reply #6 on: November 02, 2011, 06:47:25 AM »

Ok Bert, I´m with you  Wink
« Last Edit: November 02, 2011, 08:27:43 AM by wreckbender » Logged

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