Cumulus (oz5363)


Cumulus (oz5363) by Ben Shereshaw 1937 - plan thumbnail

About this Plan

Cumulus. Free flight gas model. Classic design.

This full-size plan seems to be a faithfully drafted enlargement of the original Cumulus drawings that were printed in Flying Aces 1937. This is good because the original drawings (see supplement file) needed a lot of scaling up and did not show details like individual wing ribs. Plan says 'Drawn by Ben Shereshaw' but that might mean model design rather than actual drafting(?).

Quote: "Construct the 'Cumulus', by Ben Shereshaw. There's no thrill to compare with the joy of handling a real airplane in flight.! But perhaps the nearest approach is to launch a sky-scooting gas job into the air. And great indeed is the enjoyment if the gas fan has made his plane himself. You are assured of satisfaction and success in gas model flying, if you'll build this new ship of Shereshaw's - the 'Cumulus' - for she's inherently stable. And what's more - she's easy to build!

IN designing this Cumulus model for Flying Aces gas model fans, I have tried to combine scale appearance with con-test performance. In other words, the Cumulus - named after the massed cloud formation - is a ship that not only looks good, but also has what it takes when it comes to satisfactory performance.

Because of her high thrust line, she is an extremely stable flyer and you can depend upon her every time - if you carefully follow my instructions for building her. She has a good glide ratio - around fifteen-to-one with power off.

In preparing these instructions, I have assumed that the out-and-out amateur would not yet be ready to build this gas model. So while the Cumulus is really an easy ship for the chap who has had a little model making experience (Herb Denaci, who built the original model from my plans, is sixteen years old), I have glossed over the details that such a model hobbyist would normally know and have stuck entirely to the straight, practical end of the construction.

If, however, any reader should run into difficulties in connection with this model, he has only to drop me a note with a self-addressed, stamped return envelope and I'll do my best to straighten him out.

Fuselage. The first step in building the fuselage is to lay out the side elevation. This is done by scaling the side view up to full size, with an architect's or mechanical engineer's scale. The longerons are made of 1/4 by 1/4 hard balsa, and are selected for their uniform texture and even bending characteristics - since longerons having variable bending qualities are apt to distort the fuselage.

The fuselage sides should be assembled on a piece of plywood or similar material, which must be absolutely level. Cut the compression members to size, and insert them at the proper stations as indicated on the plates. Then, cut your diagonal braces, and be sure to cut them so that part of the diagonal rests against both the longerons and the compression members. You will note that the diagonal bracing at the nose is of 1/4 by 1/4 balsa, and the diagonal brac-ing backward from the wing is of 1/8 by 1/4 balsa.

See that each member makes a snug fit, and do not try to correct a poor fit by filling the crevice with cement. Use the very best cement available, and proceed by cementing all the compression and diagonal members securely in place.

The next step is the assembly of the fuselage. Our top longeron being straight and the lower one curved, it is easier to assemble the fuselage inverted. Start by cutting the cross-members, then cementing the center portion of the fuselage together. Be sure to cement both the top and lower members to the fuselage sides at the same time, Following this procedure, work back until you have reached the stern post..."

Direct submission to Outerzone.

Added article, thanks to Orange&White.

Supplementary file notes

Article. Includes original drawings, as published 1937.


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Cumulus (oz5363) by Ben Shereshaw 1937 - model pic

  • (oz5363)
    by Ben Shereshaw
    from Flying Aces
    September 1937 
    96in span
    IC F/F
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 25/02/2014
    Filesize: 867KB
    Format: • PDFbitmap
    Credit*: JJ
    Downloads: 5096

Cumulus (oz5363) by Ben Shereshaw 1937 - pic 003.jpg
Cumulus (oz5363) by Ben Shereshaw 1937 - pic 004.jpg
Cumulus (oz5363) by Ben Shereshaw 1937 - pic 005.jpg
Cumulus (oz5363) by Ben Shereshaw 1937 - pic 006.jpg
Cumulus (oz5363) by Ben Shereshaw 1937 - pic 007.jpg

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User comments

The completed model Cumulus photo is from which is a great build article with some very fine pics showing an RC electric version of the model.
SteveWMD - 27/02/2014
Hi Steve, Here's a photo [see more pics 003, 004] of a recently built Cumulus from the 1937 magazine. Powered with an Ohlsson 60 and has a Futaba radio. Builds light and is a real floater. Cheers,
SteveRemington - 17/06/2014
Hi Steve, I see the invitation to submit picture of Cumulus. Here are some of mine [see more pics 005, 006] is slightly scaled down I pulled it down to 83 inch span to optimise it for our vintage competition rules. I drew up my own plans from the 1937 article but they were just working drawings. 5363 is pretty faithful to the original.
AllanKnox - 08/07/2015
Hello Mary and Steve, the Cumulus [more pics 007] is by Ben Shereshaw from Flying Aces 1937, 96in span, IC F/F. I dropped the wing position slightly to mount the wings without rubberbands showing, otherwise, it's per plan converted to RC and electric motor. Build for it is in RCGroups and video is here Ben Shereshaw certainly knew how to design a nice model and he would have been chuffed to bits to read in a recent newsletter covering Cocklebarrow vintage flyin that "the Cumulus was probably the most elegant model there". I know I was. Regards
JohnL - 01/04/2016
Hi. I have a question please. I have built and very successfully flown the smaller version Cumuless but I have a new 20cc DLE gasser I would like to put into this larger version. Although a large engine, would it be TOO large for this model? Fly at low revs just ticking over. It can swing an 17" prop. All help much appreciated
Peter Cane - 03/06/2022
Most people would stick with a 60 four stroke or maybe a 90 four stroke at the extreme. A 20cc DLE is a big heavy lump and likely to be overweight as well as overpowered. The throttle can be used to cure the latter, but the extra weight will mean it always flies rather faster then ideal. The best thing would be to scale up a little, say 110% to 115% (105"-115").
I did this with a Majestic Major scaled up to 112" span for a 25cc Suevia glow engine, the result was excellent despite an engine which weighs 1.4 kg.
Warren Brown - 04/06/2022
Thank you Warren.
Okay DLE 20 too big.
How about the 96" Cumulus with a nice brand new PAW 40 TBR RC?
That would swing a 12" prop easily.
I like the Cumulus as I have built and flown the smaller.
I also like the PAW 40.
I do not any longer have any old gassers.
My last was a Brown jnr and I had it in a Lanzo Record breaker free flight
Peter Cane - 04/07/2022
96" Cumulus would probably fly fine with a PAW40, but the climb is likely to be quite gentle.
Might need to watch the weight down the tail, or lengthen the nose but 1" or so to avoid nose weight with the smallish engine.
Personally I would probably reduce to about 84-88" to give a bit more margin for some lazy aerobatics. Just print at about 90% (86.6").
Warren Brown - 05/07/2022
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