SEN 2676
- Weighed, weighed, numbered and divided
- Into the Lion’s Den with a crumpet and spruce spar
- Ballast and performance
- Polyspan at Lost Hills
Weighed, weighed, numbered and divided*
From: Gavin Manion
Replying to Tapio’s reply to me. With great respect there is a difference between a 50 gram P30 and a 40g model with 10g of ballast. 40g is light, by the time you have a beacon and probably some sort of timer the flying weight of many people’s model is maybe 44-46g. To that you add an extra 10g. At 50g airframe I think most could build at 50.5g.
The essence of the argument, and surely John Carter’s original point, is that if you try to reduce performance by increasing model mass the natural and sensible response will be to put that extra mass into structure/technology. This may well have the effect of nullifying, at least in part, the desired decrease in performance. It will certainly drive model sophistication and frustrate those who are forced to simply add inert ballast to meet the new rules.
Simply adding inert ballast to an otherwise legal model is, maybe, one of the few actions which will not produce a technological solution in response.
Of course whether it will reduce model performance sufficiently unless it approaches PAAload proportions is open to conjecture.
Gavin
* Editor’s note Daniel 5:25. Apologies for the Biblical quote but it seemed to fit the occasion and our sport/hobby both at the micro and macro level.
Into the Lion’s Den with a crumpet and spruce spar
From:Stuart Darmon
Hi Roger,
may I offer a little context viz-a-viz my now famously unpopular P30 contest, for the benefit of those who assume my time is spent eating crumpets and dreaming up ways of ruining FF classes? The idea was part of a response to a set of rule proposals for UK domestic FF which I felt to be draconian; 30m. towlines, half rubber weights, etc. The idea of ‘payload P30’ was to find the minimum handicap that would do the job. The idea of removable ballast was chosen because, 1. the weight couldn’t be invested in clawing back performance, e.g. geared props or discus launch, and 2. the ballast could be removed when it wasn’t needed, ie when a large site was available- the problem with ‘one size fits all’ rules is that they can leave us flying unexciting models even when conditions would permit a full-on contest. By the way, another class at the same contest was ‘combined F1A’, with equal category prizes for full F1A, F1A without bunt, and F1A built to designs published in the 1950’s. We had one of the best glider entries of that season, and a three-way flyoff with one of each category involved. Gavin Manion’s wooden Czechmate maxed in the ‘thick’ evening air (despite a slightly early DT) while the slippery modern model, launched almost simultaneously and to a far greater height, glided down in around 4 minutes. Clearly we need to ban spruce spars.
Cheers, Stuart
Ballast and performance
From: Charles Markos
Musings about ballast notes: The effect of adding a 20% mass increase to
a P-30 whose wing size is regulated only by span to reduce performance may
be countered somewhat by increasing the wing area by 20%. P-30 DT time is
not a problem if the wing rather than the stab pops up as is common
practice. For most international classes where total area of supporting
surfaces is limited, adding ballast to reduce performance should probably
include regulating the location of the “dead weight” to somewhere under the
wing since aircraft design may be reconfigured by shifting area from
stabilizer to wing while increasing tail moment to provide a suitable
neutral point.
Chuck Markos
Polyspan at Lost Hills
From:Glenn Schneider
Roger,
For the Bazaar, I will have bolts of both regular and light polyspan. A bolt is 12 feet by 1 metre wide US $15.00 If interested parties let me know in advance, I can be sure to have sufficient supply. Other lengths will be available on request.
Thermals, Glenn
gtodds@sbcglobal.net