Sperry Messenger an enlargement of a 30" Peter Rake design

This all started out innocently enough while cruising thru some of the threads on RC Groups .  I bumped into  this one of a 30" Sperry Messenger designed by Peter Rake in England   http://www.rcgroups.com/forums/showthread.php?t=1049000 .  My first thoughts were what a sweet looking bi-plane.   Although I've never had any contact with Peter Rake, I knew his designs and models are well known.  I followed the thread for while and began thinking what a wonderful model this would make if it was larger.  To make a long story short, I contacted Peter and asked him if I could collaborate with him on a 60" ws, 1/4 scale sized Sperry Messenger.  He got right back to me with approval.  I'm not sure how this will play out.  I'm using his 30" design, enlarged to 60".  We will make some changes as to the structure, but I don't want to make it appear as if I'm "taking-over" the design.  I am honored to be in collaboration with >the< Peter Rake.  We'll see how this plays out.  Construction will start early July.  I need to be finished by about October 1st so I can start the Mue-23 dual build with Don Bailey http://home.comcast.net/~guilfoyle72/mue-23.htm

The real airplane only has a 20 foot wingspan, so at 60", it's a 1/4 scale model.  It should be a lightly loaded, good flying model.  It's small enough to be very maneuverable especially with ailerons on both upper and lower wings.  It has no flying wires to contend with and to keep in rig.  However it does have some very draggy diagonal struts.  Building  the exposed cylinders for this sized model will be a challenge.  I'm glade there are only three of them.  Studying the 3-views, the model looks like it will be very light.   My thoughts are to build it with the removable wings.  This will make transporting it easy.  Thoughts of other changes will be worked out with Peter.  This is his design, I just want to tweek it for 1/4 scale. 

Sperry_Messenger50percent.jpg (115185 bytes) Sperry_Messenger_Statistics sm.jpg (67993 bytes) EL-2002-00576.jpeg (34003 bytes) 2909069316_680f7f86082.jpg (108531 bytes) sperry-m1a.jpg (89559 bytes) 2909068926_023fd940ec.jpg (106361 bytes)  IMG_0886.jpg (76360 bytes) IMG_0888.jpg (70990 bytes) IMG_3053.JPG (149730 bytes) IMG_3013.JPG (205902 bytes) IMG_2997.JPG (147901 bytes) IMG_2999.JPG (169838 bytes) Img_3146.jpg (68599 bytes) IMG_3552.JPG (99417 bytes) IMG_3561.JPG (99953 bytes) IMG_3618.JPG (94535 bytes) IMG_3641.JPG (106426 bytes)IMG_3640.JPG (96449 bytes)IMG_3656.JPG (140583 bytes)  IMG_3670.JPG (57674 bytes)
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06-25-09: I've got the OK to work with Peter on a larger version of his 30" design.  I'm working on getting his full size plans so I can enlarge them.  His software program won't talk to mine so it might take a few days to get the drawings and get started. The yellow model above is his 30" model built by Sperry on RC Groups.   
07-2-09:  I don't have the plans yet, but doing some quick figures,  1/4 scale might be a little too big.  Though only 60"ws, the wheels would be 6" dia, scale prop would be 19" dia, and it would be >29"< tall.  The relatively moderate wingspan is deceiving.   I will go for a smaller airplane, maybe 48" ws (1/5th scale).  That would be a 4 3/4" dia wheel, and a scale prop of 15" dia prop.  Fuselage length would be 42", wing chord 9.6".    I think that's a  much more desirable airplane for me.
07-02-09:  I have plans now.  60" is too big, 48" is too small.   I'm going for 53" ws.  That's just under 1/4 scale, more like 1/4.5.  Construction starts July 6th .
07-20-09: Both wings are 90% done, fuselage is basically framed, tails' done .  Pretty good progress, but I won't be doing any more work on it for a couple weeks.
8-06-09:  Lower wing joiners are installed.  Next couple weeks I'll be working on upper wing attachment, fittings, and struts.
8-26-09:  Wings are fully installed.  I'm read to cover the wings and tail.  Tops will be orange, bottoms will be gray.
9-23-09:  I finished covering the model today.  I still have a ton of misc. things to take care of,.... and the fiberglass cowl , dummy motor, and homemade wheels,..... but it's coming together very nicely.  Maiden flight mid October looks to be right on schedule.
10-07-09:  Construction is finished,.... 3 month build..  I still need to balance and rig control throws, but the maiden flight will be this weekednd.
10-10-09:  Maiden Flight: She Flies! Weather was a clear, bright fall day, little wind, with an occasional "puff" of wind now and then, but all in all a very nice day to fly. On the first takeoff, the model pulled left and climbed more than I would have liked, but was still totally manageable. I held the stick accordingly until I reached a safe altitude and could breath again . I trimmed the transmitter so further flight was more comfortable. She flies fine. All I did was putt around the sky on the first flight. First landing was fine, but I rolled off the edge of the runway and it nosed over when it hit tall grass along the edge. The following several takeoffs were just fine, the couple landings afterward were fine, with no sign of nosing over after touch down. That's without an over large amount of elev. throw. CG was as shown on the plans. I didn't do a lot on the two flight s I did, mostly cruising around, not even a dive test for cg. I >did< do one loop. That's about it. I'd make a very pathetic test pilot. I was happy just to get it up and down safely.

It was a good day. I'm totally happy with the model. I'll work out the fact it pulls "left and up". I did not put any down thrust in it even though Pete >does< show it on the plans..... I guess I might need some .... maybe some right thrust as well. Wing incidence is set at +1 degree for both upper and lower wings, with stab at 0. To be honest, I'm not really sure what is "correct" for a biplane. The undercambered wing provided more lift as well I'm sure. It flies. I'm happy. On the next project, a Mue-23 motorglider

Fred Guilfoyle

Weight ready to fly 

  87 ounces  (5.4 pounds)

wing span

  53" ws

wing area

  1100  sq in. WOW!

Fuselage length  47"

wing loading

  ~ 11.3 oz per sq ft.  


  Axi 2826   


14 x 7 APC

motor battery

 3s lipo 3850


 36 amps

watts  400 w
watts/pound  80 watts / pound

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