Kwik-Fli, Slow Build: Weight

Kwik-Fli, Slow Build Blog Series header graphic. With a close-up of the model's engine at center, the graphic is done in orange and blue.Reading through Beppe Fascione’s work log, you’ll see plenty of mentions of how much a component or the whole model weighs.  For example:

March 9 2011 – “Now I have to find some soft and light 1/16” balsa for covering: I do not want to put too much weight on the tail!”

30 May 2011 – “For a very small weight penalty, I would rather prefer to cut two more ribs (medium-hard balsa), epoxy the plywood center ribs to them and have a much stronger landing gear structure!”

And coming up later this year – 9 November 2012 – “Final weight is around 2,570gr., quite in line with the expectations and not dissimilar from the weight of the predecessor. The expected weight (pg. 40) was 2,565gr, so I would say: ‘Close enough!’”

And, of course, on 29 June 2011 there was a lengthy discussion about weight, including a chart of how much each component of the model weighs, and the comment, “This wing is only 65 grams lighter (10%), but I think it looks nicer… Besides, this also comes from a Kit and the balsa could have been much lighter…”

Scan of the Kwik Fli Mk. II weight chart. Here's the info: Wing (+servo) Gr. 685 Fuse Gr. 420 Servos (3) Gr. 153 Landing Gear Gr. 120 Wheels Gr. 120 Fuel Tank Gr. 69 Engine + Muffler Gr. 527 Engine Mount + Prop Gr. 22 Battery, Switch, Rx Gr. 136 Total Gr. 2,252As one of the four forces of flight, weight is a pretty vital component in how well a model flies. If it is too light, it might be knocked about by winds and not fly well. If it is too heavy, the engine won’t have enough power the model sufficiently. Beppe is focused on this in his 29 June entry, as it concludes with, “The Mk. II should come out 300 grams (or 10 oz, at least) lighter than the Mk. III, therefore around 93 ounces, or 5.8lb. Good! The ENYA 60 III will be very happy!”

Every part of the model – from the balsa wood used in the frame, to each layer of dope put on the covering adds weight to the model. All of this adds up, which is why it is so important to make sure that every bit weighs the least amount possible.

Next post: July 15, 2020

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