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Old Oct 01, 2009, 11:51 AM
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Ajax, Ontario, Canada
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>What's a Gypsy?

Besides KeilKraft's offering - spelled Gypsy or Gipsy depending upon various box labels - there's also the popular Earl Stahl 'Gypsy'
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Old Oct 01, 2009, 01:00 PM
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carbondale il
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The Gypsy in the picture with a 40" wing-span is not the one I'm thinking about. Penn Valley Hobby Center has a Campbell's Custom Kits Gypsy with a 45" span at $53. It's out of stock right now, it must have been in high demand.

Twisted Sheets, Congratulations! It's a thrill huh?

Kev
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Old Oct 01, 2009, 06:01 PM
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carbondale il
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The ribs for the two wings of the TM Scout are rather intricate. There are a lot of them. I was going to cut new ones from lighter sheet wood but it would be very difficult with the tools I have. The stock wood is laser cut but like Guillow's typical wood, they are heavy. So I'm drilling holes in them. I'm going to use a jeweler's saw and connect the holes cutting out around 50% of the wood. It will be kind of like the laser cut ribs for the Herr Engineering Corsair which came already cut like this stock in the kit. I bought my cordless drill for $12. at the pawn shop. It won't hold a charge for long but with a 1/8" wood bit it's doing the job. The ribs where the struts are secured need to be 3/32" think but are cut from 1/16" think wood. I'm going to modify these by widening the slots.

Kev
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Old Oct 01, 2009, 06:12 PM
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>Campbell's Custom Kits Gypsy with a 45" span

The Stahl design, with single-blade folder
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Old Oct 01, 2009, 06:19 PM
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carbondale il
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Since my last post I've had a changa of heart. I'll go ahead and order some 1/20" think balsa sheets - A to B grain 4 to 6 lb. with my order tomorrow and give cutting them out with an X Acto knife a try. I don't have anything to loose, I can always use the wood for the smaller self designed plane which I'm thinking about building after all. I just need to decide on a size. I'll take another look at the AMA competition classes.

Kev
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Old Oct 01, 2009, 09:08 PM
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carbondale il
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My plane, with a 28" wing-span will qualify in the Moffett event 128 class. What does: "Cross Section - The fuselage cross section at the point of maximum area shall be at least "length" squared divided by 150" mean? - Taken verbatim from the AMA outdoor free flight regulations. I understand everything else.

Kev
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Old Oct 01, 2009, 09:43 PM
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Overall length of fuselage .. squared .. divided by 150 = the minimum cross section of the fuselage Example for a hypothetical 30" fuselage ... 30 x 30 = 900 divided by 150 = 6 square inches minimum x-section
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Old Oct 01, 2009, 10:30 PM
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carbondale il
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Thanks Applehoney, That's clear but is that looking from the front? If so, the length is 22". The fuse at it's largest area is 3" x 1.75". So the math comes out to be 5.25 sq. in. The minimum area works out to be 3.23 sq. in. Did I do that right?

Does the airframe weight include the three point undercarriage? My guess is the propeller and rubber do not need to be included...?

Kev
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Last edited by kevin matthews; Oct 01, 2009 at 11:23 PM.
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Old Oct 01, 2009, 11:47 PM
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Ajax, Ontario, Canada
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Overall length.

X-section is fine

Airframe weight includes everything except the rubber motor itself
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Old Oct 02, 2009, 08:06 AM
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carbondale il
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Okay, Thanks Applehoney. This model might be a contender. I have the plans almost done. It's similar to the Anna Jr. I wanted to make use of a stab with an airfoil so I didn't think the design would translate to an embryo or a Bostonian. I'm debating on the propeller size - either a 9 1/2" or an 11". The Moffett airframe must weigh at least 3.5 oz. I think I'll just wing it NPI, and see how much it weighs afterword, building light. I can always add weight. I got lucky in that the design was reduced to 75% of the large plane and comes out with a combined wing and stab area of 191 sq. in. A Gizmo Geezer thrust button will make for some easy fine tuning of the propeller side/down thrust adjustments.

Kev
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Old Oct 02, 2009, 10:09 PM
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carbondale il
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I have the guts cut out of the Scout ribs except for a couple that I missed. I'm waiting for the drill to charge. If you need to do any cope saw cutting a jeweler's saw is the way to go. The extremely small blades are made for cutting metal. It cut through balsawood fast and clean, and just a little sanding is required for the burrs. The smallest wood bit I was able to find is for 1/8" holes and just the right size for "thinning" the wood.

Free flight is like riding a bicycle with a strong cross wind.

Kev
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Old Oct 03, 2009, 12:59 AM
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carbondale il
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The Moffett rules state the total wing and stabilizer area combined must not exceed 202 sq. in. Do I have that right? The airframe weight must be at least 50 grams per 100 sq. in. of the wing area only. Do I have that right?

Kev
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Old Oct 03, 2009, 08:15 AM
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Correct on both counts
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Old Oct 03, 2009, 09:46 AM
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carbondale il
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Thank you Applehoney. Once again you have helped though one day I might be competing against you. I'm real excited about this "Moffett" plane with no name yet. Last night I added the three wheel undercarrage to the fuse plan. I also have fine tuned what the construction will be. I've been building the longerons for this design; the Legal Eagle and the large plane by making the fuselage in three separate pieces. This one will be built with single sticks running the entire length and then curved to join at the front and rear as Bruce M. suggested. Since it is a ROG competition I think I'll need an 11" propeller with 2 loops of 1/4" rubber. That's where I'm going to start. I designed the fuselage for this one so I can simulate cabin windows with black tissue and the cabin area is a little more aerodynamic.

Kev
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Old Oct 04, 2009, 12:09 PM
Free Flight rubber flyer
South Carolina
Joined Mar 2005
497 Posts
Kev, that will be ok for a first try at Moffett, but it won't hold up in competition. Here are the parameters for a standard Moffett:
150 sq in wing
50 sq in stab
40" span
38" length
75 g airframe
18-22" prop
power: 20-22 strands of 1/8 x 50 g.

You need as much rubber as you can possibly cram into the airframe and not have it collapse or become uncontrollable. These airplanes climb as fast as the older power models. First 5-10 seconds is straight up going faster than you can imagine, and the wings must be constructed with union jack ribs to prevent wing flutter at the high speeds experienced on climbout. These are without a doubt the fastest climbing rubber models in use today.

Joe Williams' design seems to be the most popular.
Benstein has a VTO model that's pretty intimidating.
This year's winner:
http://kenanne.50megs.com/BongEagles...ts/008Nats.jpg
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