As I mentioned in another thread, I have corresponded with Lynn Williams of Flitzer biplane fame for several years, and one of the topics we have discussed is the little Sperry Messenger (aka Verville-Sperry and sometimes M-1) either as a replica subject or inspiration for a new design.
Here are some links if you are not familiar with this little biplane:
https://en.wikipedia.org/wiki/Verville-Sperry_M-1_Messenger
https://airandspace.si.edu/collection-objects/verville-sperry-m-1-messenger
https://www.cradleofaviation.org/history/exhibits/atrium/sperry_messenger.html
I have gone through my older messages and here are some highlights and attachments shared with Lynn's blessing. Text in italics is Lynn, and these comments and images are pulled from messages going back to 2010.
Here are three more images from my scrap collection of Sperry drafts. Very rough, and I haven't shown the more intricate Anzani notes as my scanner's playing hard to get. Seen here are side views for the full size and 90% scale M.1s, (20' and 18' spans), as well as a plan view of the 80% scale, 16' span.
As I suggested, the 18' span at 42" chord provides ample area at 126' sq. not allowing for cut outs, or 132'sq. at 44" chord. The latter equates to an AR of 4.9 (5:1) while the smaller chord gives 5.142:1. However the actual biplane aspect ratio is much lower with the high stagger taken into consideration. But this affects tail arm and tail volume more than induced drag as the magnitude of the biplane vortices are independent of stagger. The long tail moment and very adequate horizontal tail area are OK.
I think that a 90% Sperry will tick the boxes and be as close to full size as makes no difference, but will have much lower mass as a result, as well as being designed for minimum weight.
80% 90% 100%
[Lynn and I also discussed his "Aerial Messenger" concept, basically a slightly simplified Flitzer with longer wings to suit the European 300 kg gross weight single-seat microlight category. One was begun in the UK but I don't believe it was ever finished.]
Here's a clearer side elevation of the Aerial Messenger microlight which is derived from the Flitzer Z-1. I will re-draw this shortly as a sharp-outlined colour rendition.
It has many simplifications including almost no duo-curvature of metal panels in the engine cowling - just the merest curve on the upper fore-decking.
Rear fuselage upper cross-section consists of a truncated pyramid shape with a rolled aluminium headrest - 'Coke can material', very springy and ultra light. It has a lot more wing than a typical Flitzer and spans 19'.
The little 3-cylinder Verner 3V should power a lightweight Sperry replica perfectly well, the same size as a Flitzer at 18' span. The more forward cockpit location would allow balance with such an engine weighing only 80 lbs. and it would look completely authentic.
To return to the Sperry M.1, as I recall it was used for some aerofoil experiments, so building it light but with the deeper spars afforded by a USA 27 section at 15% T/C ratio, which has the same useful mobile CP as the 35B, used on the Flitzer, it could be immensely strong and still comply with the SSDR category.
The upshot of these conversations is that the Sperry Messenger is particularly well-suited to building a modern replica even at 100% scale. Just so you don't think such a plane would be a dog with just 45 hp from a Verner 3VW, here is a video of an X-Plane simulation of a Flitzer Goblin (simplified, lightweight model) of comparable size and weight with that same engine.
https://vimeo.com/156087648
Cheers,
Matthew
Here are some links if you are not familiar with this little biplane:
https://en.wikipedia.org/wiki/Verville-Sperry_M-1_Messenger
https://airandspace.si.edu/collection-objects/verville-sperry-m-1-messenger
https://www.cradleofaviation.org/history/exhibits/atrium/sperry_messenger.html
I have gone through my older messages and here are some highlights and attachments shared with Lynn's blessing. Text in italics is Lynn, and these comments and images are pulled from messages going back to 2010.
Here are three more images from my scrap collection of Sperry drafts. Very rough, and I haven't shown the more intricate Anzani notes as my scanner's playing hard to get. Seen here are side views for the full size and 90% scale M.1s, (20' and 18' spans), as well as a plan view of the 80% scale, 16' span.
As I suggested, the 18' span at 42" chord provides ample area at 126' sq. not allowing for cut outs, or 132'sq. at 44" chord. The latter equates to an AR of 4.9 (5:1) while the smaller chord gives 5.142:1. However the actual biplane aspect ratio is much lower with the high stagger taken into consideration. But this affects tail arm and tail volume more than induced drag as the magnitude of the biplane vortices are independent of stagger. The long tail moment and very adequate horizontal tail area are OK.
I think that a 90% Sperry will tick the boxes and be as close to full size as makes no difference, but will have much lower mass as a result, as well as being designed for minimum weight.
80% 90% 100%
[Lynn and I also discussed his "Aerial Messenger" concept, basically a slightly simplified Flitzer with longer wings to suit the European 300 kg gross weight single-seat microlight category. One was begun in the UK but I don't believe it was ever finished.]
Here's a clearer side elevation of the Aerial Messenger microlight which is derived from the Flitzer Z-1. I will re-draw this shortly as a sharp-outlined colour rendition.
It has many simplifications including almost no duo-curvature of metal panels in the engine cowling - just the merest curve on the upper fore-decking.
Rear fuselage upper cross-section consists of a truncated pyramid shape with a rolled aluminium headrest - 'Coke can material', very springy and ultra light. It has a lot more wing than a typical Flitzer and spans 19'.
The little 3-cylinder Verner 3V should power a lightweight Sperry replica perfectly well, the same size as a Flitzer at 18' span. The more forward cockpit location would allow balance with such an engine weighing only 80 lbs. and it would look completely authentic.
To return to the Sperry M.1, as I recall it was used for some aerofoil experiments, so building it light but with the deeper spars afforded by a USA 27 section at 15% T/C ratio, which has the same useful mobile CP as the 35B, used on the Flitzer, it could be immensely strong and still comply with the SSDR category.
The upshot of these conversations is that the Sperry Messenger is particularly well-suited to building a modern replica even at 100% scale. Just so you don't think such a plane would be a dog with just 45 hp from a Verner 3VW, here is a video of an X-Plane simulation of a Flitzer Goblin (simplified, lightweight model) of comparable size and weight with that same engine.
https://vimeo.com/156087648
Cheers,
Matthew