Sopwith Tripe Axle

[Seawinder]

It's been something of a struggle, but I'm finally getting close to finishing an Eduard 1/48 Tripe. I'm hoping someone can explain the installation of the axle. The kit has it as a straight rod that is supposed to attach to the gear struts at the angle where they meet. Museum photos, however, appear to show the axle attached to the top center of the airfoil cross piece and flexing upward to where the wheels attach. I'm thinking this was to allow the axle to act as a suspension spring as well. Is my assessment correct? If so, does that mean the axle piece should be bent so that it can attach in three places? If that's so, do the wheels cant inward at their tops to stay perpendicular to the axle?

 

Thanks in advance, Pip

[europapete]

Hi Pip. The "axle" is in multiple pieces. There were two spreader bars going between the u/c legs. These were solid, none moving parts. Between these bars, were the actual axles. They were anchored in the center on a hinge bracket to the two spreader bars. They went through a slot in the U/C legs at the outer end and were secured with bungee chords so they could pivot up and down for suspension. When in flight, the axles would take on a slightly negative angle, and the tops of the wheels would splay out a little. When stationary on the ground, the axles would have a slight positive angle and the wheels would be tilted in at the tops. The axles, obviously, were always 90' to the wheel. Some A/C had a wooden fairing bolted to the two spreader bars to cover all this up. Hope this helps, regards, Pete. 

[Seawinder]

19 minutes ago, europapete said:

Hi Pip. The "axle" is in multiple pieces. There were two spreader bars going between the u/c legs. These were solid, none moving parts. Between these bars, were the actual axles. They were anchored in the center on a hinge bracket to the two spreader bars. They went through a slot in the U/C legs at the outer end and were secured with bungee chords so they could pivot up and down for suspension. When in flight, the axles would take on a slightly negative angle, and the tops of the wheels would splay out a little. When stationary on the ground, the axles would have a slight positive angle and the wheels would be tilted in at the tops. The axles, obviously, were always 90' to the wheel. Some A/C had a wooden fairing bolted to the two spreader bars to cover all this up. Hope this helps, regards, Pete. 

Hi Pete. That's a huge help, thanks! I'll cut the single axle rod and reattach the pieces at the appropriate angle.

[Rob G]

The Wingnut Wings instruction sheet for their 1/32 version may be of use. Find it here

 

http://www.wingnutwings.com/ww/productdetail?productid=3039&cat=4

 

[malpaso]

Bear in mind the bungee was wrapped up pretty tight or it wouldn't provide the shock absoption.  And these planes were very light so unless the bungee was knackered, the change in angle would be fairly mild.

The RAFM Rigging Notes reprint doesn't record details for the bungee on Sopwith types, but on the BE2d or BE2e there is 38 feet of 3/8 dia elastic to each wheel!  "Care should be taken that these are well secured, but not too tightly bound, as this would make landings too harsh."

"When the Shock Absorber is properly fitted the weight of Machine in flying condition should stretch the elastic until the axle just clears the inside of the "V" Undercarriage Struts."

The BE2 types had a straight axle, but the shock absorption system was similar on all types of British WW1 aircraft.  It seems an enormous amount of bungee to me (BE2c recorded as 44 feet,) I assume it would have to be measured out slack (unless there was a regulation for stretching bungee for measuring, with exact stretch/ load figures) so the effective length once wound on the undercart would be very much longer to get the stretchiness needed?

[Paul Thompson]

44 minutes ago, malpaso said:

Bear in mind the bungee was wrapped up pretty tight or it wouldn't provide the shock absoption.  And these planes were very light so unless the bungee was knackered, the change in angle would be fairly mild.

The RAFM Rigging Notes reprint doesn't record details for the bungee on Sopwith types, but on the BE2d or BE2e there is 38 feet of 3/8 dia elastic to each wheel!  "Care should be taken that these are well secured, but not too tightly bound, as this would make landings too harsh."

"When the Shock Absorber is properly fitted the weight of Machine in flying condition should stretch the elastic until the axle just clears the inside of the "V" Undercarriage Struts."

The BE2 types had a straight axle, but the shock absorption system was similar on all types of British WW1 aircraft.  It seems an enormous amount of bungee to me (BE2c recorded as 44 feet,) I assume it would have to be measured out slack (unless there was a regulation for stretching bungee for measuring, with exact stretch/ load figures) so the effective length once wound on the undercart would be very much longer to get the stretchiness needed?

Nonetheless, the toe-ing in effect is clearly visible on many photos of Sopwith types.

 

Paul.

[Seawinder]

6 hours ago, malpaso said:

"When the Shock Absorber is properly fitted the weight of Machine in flying condition should stretch the elastic until the axle just clears the inside of the "V" Undercarriage Struts."

That's handy since Eduard has the axle(s) attached to the inside of the "V"s.

[Seawinder]

6 hours ago, Paul Thompson said:

Nonetheless, the toe-ing in effect is clearly visible on many photos of Sopwith types.

 

Paul.

Hi Paul. What do you mean when you say "toeing in?" If I read Pete's post correctly, it would seem to be "toeing out" with the tops of the wheels slanted inwards to remain perpendicular with the axle(s).

[Paul Thompson]

1 hour ago, Seawinder said:

Hi Paul. What do you mean when you say "toeing in?" If I read Pete's post correctly, it would seem to be "toeing out" with the tops of the wheels slanted inwards to remain perpendicular with the axle(s).

Nomenclature, eh? No, I meant what he said, tops in when on the ground. I've always called that toeing in, but it depends on if you're looking at the tops or bottoms of the wheels, which now I consider it could be confusing. Put it down to living in Brum for the first 18 years of my life...................

 

Cheers,    Paul.

[Seawinder]

43 minutes ago, Paul Thompson said:

Nomenclature, eh? No, I meant what he said, tops in when on the ground. I've always called that toeing in, but it depends on if you're looking at the tops or bottoms of the wheels, which now I consider it could be confusing. Put it down to living in Brum for the first 18 years of my life...................

 

Cheers,    Paul.

I'm glad we're on the same page; thanks for clarifying. My confusion: "toe" implies bottom.   🙂

[Admiral Puff]

To add to the confusion: on a motor vehicle, "toe in" means that the leading edge of a pair of wheels on the same axle when viewed in plan are closer together than the trailing edges, and "toe out" means the opposite; the difference between the top and bottom of an individual wheel when viewed in elevation is called "camber".

[Paul Thompson]

4 minutes ago, Admiral Puff said:

To add to the confusion: on a motor vehicle, "toe in" means that the leading edge of a pair of wheels on the same axle when viewed in plan are closer together than the trailing edges, and "toe out" means the opposite; the difference between the top and bottom of an individual wheel when viewed in elevation is called "camber".

Waaaaaaaaaaaaaaaaaaaaaaaggggggggggggggggggghhhhhhhhhhhhhhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

 

Paul.

[europapete]

lolol, sorry Paul, he is right.

[Allan31]

[Paul Thompson]

Okay, every time I say 'toe-in' in future, everyone read 'negative camber' instead, okay? And give me a sharp nudge in the ribs. In my defence, at least I still know the difference between to, two and too, which these days counts as a super power.

 

Paul.

[europapete]

That qualifies you as our Editor-in-Chief!

[Seawinder]

9 hours ago, Paul Thompson said:

Okay, every time I say 'toe-in' in future, everyone read 'negative camber' instead, okay? And give me a sharp nudge in the ribs. In my defence, at least I still know the difference between to, two and too, which these days counts as a super power.

 

Paul.

Admirable! is there anything you can do to edify the many people who say things like "Here are two photo's" on these forums? Drives me nuts.

[Paul Thompson]

1 minute ago, Seawinder said:

Admirable! is there anything you can do to edify the many people who say things like "Here are two photo's" on these forums? Drives me nuts.

Sadly, I am not an official agent of evolution. Tempting, though.

 

Paul.