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Moa

Handley Page HP42/45, Contrail vacuformed 1/72

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The Post vehicle is actually a Chrysler Airflow. 

 

The outer"rudders" are acting as aerodynamic counterbalances as they are acting forwards of the Rudder hinge line. So as the rudder turns they ad add pressure forwards of the hinge line and therefore reduce pressure on the rudder bar, ala a servo tab.

 

John

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21 minutes ago, John Aero said:

The Post vehicle is actually a Chrysler Airflow. 

 

The outer"rudders" are acting as aerodynamic counterbalances as they are acting forwards of the Rudder hinge line. So as the rudder turns they ad add pressure forwards of the hinge line and therefore reduce pressure on the rudder bar, ala a servo tab.

 

John

Thanks John

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Posted (edited)

40574460303_0ff5888e11_z.jpg

Also on the Bolton and Paul Overstrand and sidestrand

Edited by Marklo

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The servo tabs on the Overstrand and Scylla are of the normally acting type in that they act in opposition to the rudder, so that it assists in pushing over the rudder and so reduces the load.  Most later ones would be built into the rudder trailing edge.

 

The HP 42 type are unusual in that they are acting to assist the rudder over from the front.

 

As I see the action, the Tab/airfoil is hinged on it's trailing edge by the upper strut/rod and the lower edge bearing on the tail plane. The middle strut/rod, of which one end is connected to a bellcrank on the rudder, which projects forward of both the rudder and Tab/airfoil pivot points. The other end connects to the tab/airfoil near to it's leading edge, so that as the rudder moves over it deflects the Tab/airfoil in the same plane, thus relieving some of the rudder load.

 

I agree with Aeronaut in that the top tail plane appears to have variable incidence whilst the lower one is fixed.

 

John

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11 hours ago, John Aero said:

The Post vehicle is actually a Chrysler Airflow. 

John, if you follow the link you gave to the Dinky Toys Collectors Association post with the photo's, there's a description of this as being a Morris 15cwt van chassis with a custom Duple coachworks body built for the GPO to promote airmail services.

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Those are not servo tabs on the HP42, but aerodynamic balances, in lieu of the mass balances often fitted to smaller aircraft.  Similar aerodynamic balances were sometimes fitted to the ailerons and elevators of contemporary aircraft eg Dornier. 

 

The surfaces hanging off the back of the rudder on the Scylla,etc,  ARE servo tabs, or as they were usually known back then, Flettner tabs, after their originator.  They are the surfaces connected to the controls and used to move the larger control surface,

hence giving reduced control forces.

 

 

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Posted (edited)
22 hours ago, dogsbody said:

 

Then what is this?

 

40571138443_0e70bb4b23_b.jpg

 I didn't even see those, but as stated above they are balances, not servos. As you say, I was looking at the rear edge of the rudder!

 

https://www.boldmethod.com/learn-to-fly/systems/4-types-of-trim

 

Ian

Edited by limeypilot

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Dave,

I too have read the comment about the Morris. I've always understood the vehicle to have been a special bodied Chrysler Imperial Airflow. It's much higher than a 15cwt Morris van which is a Morris 8 hp chassis.  I was  thinking that someone got confused with a Morris Series E Van. which has got some flowing lines but it didn't come in until around 1936  The Morris chassis used 17" wheels so I'll see if I can do a ratio check on the cars wheelbase..

 

I always though it a little odd to park a "modern" streamlined car together with a built in Headwind 😃

 

John

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Dave, I too have seen the comment about the Morris. the vehicle is definitely a Chrysler Airflow. Imperial had a few of them with special body work. It's much higher and longer that a 15cwt Morris van which is a Morris 8 hp chassis.  I think that someone got confused with a Morris Series E Van. which has got some flowing lines.

 

I always though it a little odd to park a "modern" streamlined car together with a built in Headwind 😃

 

John

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54 minutes ago, John Aero said:

I always though it a little odd to park a "modern" streamlined car together with a built in Headwind 😃

 

John

Ditto!

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A larger view of a Post van.

 

40577529333_df67785843_b.jpg

 

 

 

Chris

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I wasn't satisfied with the kit's floor and floorplan, so I cut a new floor from styrene sheet and adjusted the locations of dividers according to another source. Besides, the same way I doubled the bulkheads with corrugated styrene where they may be seen that way from both sides, I added smooth styrene to the smooth side of the bulkheads that face the cabin, since the cabin side of those bulkheads wasn't good enough:

IMG_3195+%25281280x960%2529.jpg

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The kit has the spaces smaller:

IMG_3196+%25281280x960%2529.jpg

 

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The interior fits comfortably in the fuselage sides, and the two portholes align well with the bathrooms. The parts seen on top are the bathroom walls and doors. The surfaces of all parts in the kit have many pips and some imperfections, product of the vac cottage process. Those will need a few sessions of fixing:

IMG_3198+%25281280x960%2529.jpg

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23 hours ago, John Aero said:

 

The outer "rudders" are acting as aerodynamic counterbalances as they are acting forwards of the Rudder hinge line. So as the rudder turns they ad add pressure forwards of the hinge line and therefore reduce pressure on the rudder bar, ala a servo tab.

 

John

A couple of the first Lockheed Sirius built were experimentally fitted with similar aerodynamic counterbalances on the rudder.

If you closely study photos of Charles Lindbergh's Sirius being tested at the Lockheed plant you'll see these fitted.

They must not have worked well as they were quickly removed.

 

Tim

 

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The surface is riddled with imperfections, as you can see. Even as old as this kit is, it seems that is going through puberty, and its covered with zits:

IMG_3199+%2528960x1280%2529.jpg

 

 Oh, Lawdy Lawd, as someone infamously said:

IMG_3200+%25281280x960%2529.jpg

 

And yet, a valiant, if not successful attempt was made by the manufacturer to represent surface detail as rivet rows and such:

IMG_3201+%25281280x960%2529.jpg

 

IMG_3202+%25281280x960%2529.jpg

 

 I will have to make a tool to pass along the corrugations to clean some of those pips. The bigger ones leave pinholes when removed. Oh the delights of modeling...

IMG_3203+%25281280x960%2529.jpg

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12 hours ago, John Aero said:

The servo tabs on the Overstrand and Scylla are of the normally acting type in that they act in opposition to the rudder, so that it assists in pushing over the rudder and so reduces the load.  Most later ones would be built into the rudder trailing edge.

 

The HP 42 type are unusual in that they are acting to assist the rudder over from the front.

 

As I see the action, the Tab/airfoil is hinged on it's trailing edge by the upper strut/rod and the lower edge bearing on the tail plane. The middle strut/rod, of which one end is connected to a bellcrank on the rudder, which projects forward of both the rudder and Tab/airfoil pivot points. The other end connects to the tab/airfoil near to it's leading edge, so that as the rudder moves over it deflects the Tab/airfoil in the same plane, thus relieving some of the rudder load.

 

I agree with Aeronaut in that the top tail plane appears to have variable incidence whilst the lower one is fixed.

 

John

 

One of the many Goldberg Variations on the theme:

43.jpg

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9 minutes ago, Moa said:

The surface is riddled with imperfections, as you can see. Even as old as this kit is, it seems that is going through puberty, and its covered with zits:

 

 Oh, Lawdy Lawd, as someone infamously said:

 

 

It might be worse - you might have chosen a scheme in natural metal finish, where every imperfection would be highlighted....😀

 

Looking forward very much to seeing how you work through this.

 

Cheers,

 

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20 minutes ago, Jinxman said:

you might have chosen a scheme in natural metal finish, where every imperfection would be highlighted.

I did exactly that.

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Assuming that the chassis is a straight 15 cwt van type then the wheels will be the 17" type so using this information, the Morris wheel base will be 7' 6". I printed out the photo to have 34 mm wheels and measuring from the photo the wheel base is near 160 mm. so dividing 160 by 34 gives us a ratio of close to 4.7. so 17" times 4,7 gives us 79.9" which allowing for small errors give us a close wheel base to the Morris chassis of 7' 6" so it's very likely the  vehicle was a Morris. The wheel base of the Airflow would be much longer.

 

Again by ratio the height of the bodywork is around 54" which is the standard Morris car height. The illusion of a much bigger vehicle is done by the quite narrower than standard windows. The position and angle of the steering wheel is very odd.

 

John

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Work commences to clean the imperfections on the corrugations:

IMG_3206+%25281280x960%2529.jpg

 

Same area cleaned up (before the escape hatch)

IMG_3207+%25281280x960%2529.jpg

 

And again a couple of those ridges:

IMG_3208+%25281280x960%2529.jpg

 

And gone:

IMG_3209+%25281280x960%2529.jpg

 

If the surface is not immaculate, it is much better than what it was:

IMG_3204+%25281280x960%2529.jpg

 

IMG_3205+%25281280x960%2529.jpg

 

IMG_3210+%25281280x960%2529.jpg

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Here is the Aeroflot bus in the same scale:

IMG_3211+%25281280x960%2529.jpg

 

It fits comfortably inside the cabin:

IMG_3212+%25281280x960%2529.jpg

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You certainly seem to be making a good fist of getting rid of the zits!

 

Martian 

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Amazing how you got rid of all those zits! One of the advantages of scratch building sis that they do not have to be dealt with....

 

P

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