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Author Topic: Bostonians for Boston ...?  (Read 1982 times)
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lincoln
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« Reply #25 on: May 01, 2013, 11:38:51 PM »

Well, if you go by the AMA rules, a biplane or multiplane needs to weigh 20 grams min. instead of 14g. (7 and 10 for the indoor rules, as I recall). The following are my personal interpretations and carry very little authority unless I CD a contest again.

1. I see no reason to suppose the additional props shouldn't be required to be 6 inches max. The outdoor rules only mention prop in the singular, but since elsewhere they refer to the possibility of multiple motors, I don't think that limits you. Note that gears do not seem to be prohibited, so it might make more sense to go with gears so you can use a thick motor with a few turns to drive a small prop with many turns.There is also the possibility of this weird gadget I've seen with cranks so you can use two skinny motors on one prop, enabling you to have more turns and less torque. I think this is or was called a "Hovespian" movement. I've attached a drawing which shows such a movement used as return gears at the back of the plane so you can use two motors as one very long motor, but if you keep the center shaft, you can put it on the front. The drawing is from an Alan Booton plan for a Burnelli twin, which can be found on Outerzone.
2. I think the rules are a bit ambiguous here, but I also think you're better off putting that area in the tail. It may fall under Dannysoar's Rule: You can do anything you want as long as you don't win. (Dannysoar is aka David Dodge. He liked to do unusual aircraft models which still flew pretty well. Concorde nocal, V-173 nocal, Lee Annular, flying wings, fantasy scale, etc. Our hobby will be more entertaining if he returns to it.)
3. I read it as no max on the combined wings, but it seems somewhat self limiting. I suspect the "sweet spot" for a 20 gram model is either a biplane or triplane with a wing sized stab.

As far as I know, sweep is ok. I've seen it on some Bostonian plans. How about a Dunne?
http://www.rcaf-arc.forces.gc.ca/v2/equip/resrc/images/hst/l-g/bdunne.jpg
Might be good for some charisma points!
Or even a twin Dunne:
http://www.ctie.monash.edu.au/hargrave/images/dunne_5_2vc_350.jpg
It seems that most Bostonians are monoplanes, possibly due to the 6" prop rule. However, there are some things that are not clear to me from the rules. I have read both the AMA rules, and the ones on this forum as well.

1. It seems clear that there is a 6" max prop diameter, but the rules mention propellor(s), so for a twin, what is the max prop diameter of each prop?
2. If you make a Biplane with a tiny second wing, such that the second wing and the stab are a maximum of 24 sq in, does it then classify as a monoplane?
3. If you make a multi-plane model, and the main wing is 48 sq in, what is the maximum wing area of the secondary, tertiary, etc. combined wings?

No, I am not trying to 'beat' any rules, or even to twist them out of shape. But if I design a Bostonian variant, then I would like it to qualify as a legal Bostonian. And since I love multi-wing planes, I would like to work in that arena.

Ian
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« Reply #26 on: May 02, 2013, 08:23:52 PM »

Thanks, Lincoln.
I like the 'Dannysoar' interpretation, but I do not possess the skill set to win anything in competition. I build things that move me  (like dragon's Burnelli), even if they come dead last. I was more thinking of a Triplane along the Nieuport-Beech line with a V-tail, sort of like a Bonanza, a "NieuBeechAnzaTriplex"
Ian
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« Reply #27 on: May 16, 2013, 06:33:07 PM »

I am finally back home after some months and can (hopefully) resume work on my xp-54. But in the meantime, I have finished the preliminary design for my Bostonian Triplane, based on Walt Mooney's Nieuport-Beech Bostonian, but with a Bonanza V-tail. I am not sure about the size of the tail surfaces yet, or whether it should be a lifting surface. Here is a pic of the work to date.
Ian
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Re: Bostonians for Boston ...?
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