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Old Nov 05, 2014, 10:09 PM
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Scale Build Off 4: Glenney and Henderson Gadfly

Well, after entering the third build off with a fatally flawed Moth Minor (CG and weight issues- don't ask, it's too soon...) I'm back with a new subject, the Glenney and Henderson Gadfly- sorta, kinda, based on the Sherman Gilespie plan, but not really. Meaning I looked at it but this one was designed from the ground up and has passed muster with my now standard weight and balance spreadsheet, so she should work out just fine.

Dale
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Old Nov 05, 2014, 10:24 PM
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Just in case you're not familiar with the Gadfly(aka I re-figured out how to post images):


Dale
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Old Nov 05, 2014, 10:25 PM
The "pro" in procrastination
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Welcome back, Dale! How big is she?

Steve
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Old Nov 06, 2014, 09:10 AM
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Quote:
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Welcome back, Dale! How big is she?

Steve
Thanks, Steve.

She'll have a 50 inch span, 4 channel, powered by a Nippy Black turning a 10x6 or something close to that. I'm going to try scale-ish control cables and see how that works out.

Dale
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Old Nov 06, 2014, 10:29 AM
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Many years ago, Dave Reese published a smaller free-flight version in Flying Models magazine. Plans may be still available, though the magazine is defunct.

Alistego, where did you get your plans from?

Jim R.
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Old Nov 06, 2014, 11:44 AM
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Originally Posted by JRuggiero View Post
Many years ago, Dave Reese published a smaller free-flight version in Flying Models magazine. Plans may be still available, though the magazine is defunct.

Alistego, where did you get your plans from?

Jim R.
Hi Jim,

I don't remember the FM version but I did build a peanut scale (Modelbuilder?) version years ago and it was a great flyer. Like I mentioned I did have a look at the Gilespie plan (also a free flight model) but the plans I'm using are my own originals done in TurboCad. I just got started building her this morning and will have some pictures up soon.

Dale
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Old Nov 06, 2014, 01:34 PM
RFJ
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This is Dave Rees' 36" span rubber powered version from May 1983 Flying Models.

Some years ago I started but never finished an i/c powered 1/4 scale (75" span) model from my own plans. This thread may inspire me to retrieve it from the attic and complete it with electric power.

Ray
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Old Nov 06, 2014, 03:13 PM
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Quote:
Originally Posted by RFJ View Post
This is Dave Rees' 36" span rubber powered version from May 1983 Flying Models.

Some years ago I started but never finished an i/c powered 1/4 scale (75" span) model from my own plans. This thread may inspire me to retrieve it from the attic and complete it with electric power.

Ray
Ah, that one. I've seen video of one online, maybe Youtube, of one going bye-bye in a thermal. Didn't know about the plan. Mind, I didn't know about FM going bye-bye either. Too bad, it was the last real model plane mag left.

I'm using my usual Clark Y airfoil, D-tube wing construction with spruce spars and capstrips. Fuse and tail are very much like a free flight model using 1/4 inch strips with some sheet infill where needed.

Pictures soon...

Dale
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Old Nov 07, 2014, 07:44 PM
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Let's get this project started.

First up, a glance at the plans. These were printed off pretty early on in the design process. I've added some details since, enough for me anyway. Those green-headed modelling pins are made in Germany and are easily the best modelling pins ever. Sadly the company I got them from got out of the model supplies business.
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Old Nov 07, 2014, 07:51 PM
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Once I have everything set up and materials ready, I sort through my balsa strip stock and sort them by weight. This is useful to determine which will be used for longerons and spars and which will be used on the aft fuselage.

Once we have some idea of where these things will go, I like to start with the tail surfaces. These are as easy as they get, lots of long straight pieces.

Dale
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Old Nov 07, 2014, 07:57 PM
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Now, on to the fuselage. It's pretty much standard stick-and-tissue type construction using 1/4 inch square balsa. These days I go to great lengths to get everything squared up and secure while the glue sets up.

Dale
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Old Nov 08, 2014, 01:22 PM
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It's snowing here today. Looks like all flying will be on skis from here on in. A good day to work on the Gadfly.

Fuselage development continues and I'll have pics when there's been enough progress to show.

For now I thought I'd post some details about the plane by sharing what Motocalc 8 has to say:

MotOpinion - Gadfly (50")
2200ft above Sea Level, 29.92inHg, 51F

Motor: Uberall Nippy Black 1812/100; 1020rpm/V; 1.5A no-load; 0.064 Ohms.
Battery: Team Great Hobbies 3s 4200 mAh (30C); 3 cells; 4200mAh @ 3.7V; 0.0114 Ohms/cell.
Speed Control: Generic Brushless ESC; 0.006 Ohms; High rate.
Drive System: Generic 10x6; 10x6 (Pconst=1.11; Tconst=1) direct drive.
Airframe: 50" Gadfly; 440sq.in; 37.8oz RTF; 12.4oz/sq.ft; Cd=0.064; Cl=0.5; Clopt=0.64; Clmax=1.14.
Stats: 87 W/lb in; 65 W/lb out; 17mph stall; 23mph opt @ 55% (83:32, 91F); 26mph level @ 61% (68:10, 97F); 1100ft/min @ 32.7; -240ft/min @ -6.8.

Power System Notes:

The full-throttle motor current at the best lift-to-drag ratio airspeed (19.2A) falls approximately between the motor's maximum efficiency current (15.6A) and its current at theoretical maximum output (81.4A), thus making effective use of the motor.

Aerodynamic Notes:

The static pitch speed (49mph) is within the range of approximately 2.5 to 3 times the model's stall speed (17mph), which is considered ideal for good performance.
With a wing loading of 12.4oz/sq.ft, a model of this size will have trainer-like flying characteristics. It would make an ideal trainer, for use in calm to light wind conditions.
The static thrust (32.5oz) to weight (37.8oz) ratio is 0.86:1, which will result in very short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and steep climb-outs.
At the best lift-to-drag ratio airspeed, the excess-thrust (19.7oz) to weight (37.8oz) ratio is 0.52:1, which will give steep climbs and excellent acceleration. This model should be able to do consecutive loops, and has sufficient in-flight thrust for almost any aerobatic maneuver.

General Notes:

This analysis is based on calculations that take motor heating effects into account.
These calculations are based on mathematical models that may not account for all limitations of the components used. Always consult the power system component manufacturers to ensure that no limits (current, rpm, etc.) are being exceeded.




Dale
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Old Nov 13, 2014, 08:12 PM
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Back to the building, which actually has been coming along very nicely so far. The fuselage is pretty much framed up now, including main formers and a completed turtle deck. Just waiting for some balsa blocks for the forward fuselage/hatch area. I suppose carved foam would work too but I just prefer working with wood.
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Old Nov 13, 2014, 08:17 PM
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The wings are well on their way as well. The right one...
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Old Nov 13, 2014, 08:20 PM
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And the left one. I'm putting 1/4 inch washout into each tip so she should be pretty well mannered. Next up: the wing centre section and joining it all together.

Dale
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