How much difference do flaps make on a pattern flyer? - RC Groups
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Mar 05, 2013, 09:45 AM
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RknRusty's Avatar

How much difference do flaps make on a pattern flyer?

I can't let Tigreflyer ask all of the most interesting questions, so here's one I haven't seen. Is there much difference pattern flying with flaps, or is it just more of a pilot preference? I imagine a flapped plane will make tighter corners on square loops, wingover pullouts, etc.

I'm not expecting to fly for judges, just for my own fun, but I've always been curious. My goal this season is to get as proficient as I can at flying the pattern with my soon-to-maiden Shoestring. It has no flaps, but I think it should be fine for a beginner like me. I'm not a CL beginner, but am only proficient with 1/2A circle burning freestyle stunt madness. I'm ready to put some polish on my routine, and was given a badly wrecked Shoestring to rebuild, so that's where I am now.

It looks like I'm going to get in just under the wire at the recommended 28-30oz. The airframe is at 16.8oz and the engine weighs 10.1oz, plus the tank and LG.

Before and after pictures:
Getting all that yellow paint off was quite a chore.

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Mar 05, 2013, 10:13 AM
Old Timer
The Kiwi's Avatar
Flapped planes do fly differently than unflapped ones, but each kind should be designed to suit the choice made about coupling the flaps. The Magician 35 is one of the best examples of a classic model built both ways (Jim Silhavy's design).

It was designed with fixed flaps, and with the intended purpose of flying similarly to a Nobler. For its size (the Midwest version, seen most often, had about 480 square inches), it had a quite short tail moment, and a long, extended nose. With fixed flaps, it does fly well, but Midwest always sold kits made from relatively heavy balsa, making their kits also heavy (mine weighed 42 Ounces, both of them).

The Midwest plans suggested coupled flaps, but didn't include reference to moving the stab about 2" or more rearward when hinging the flaps. At similar weights, with the short tail, a flapped Midwest Magician flew less well than one with fixed flaps. Moving the stab made a drastic change, and given the typical kit-built final weight, (probably as much or more than my own 42 Ounce models) greatly improved the performance for stunting.

Personally, I learned a majority of the pattern maneuvers with unflapped planes, such as Goldberg's Shoestring, and Top Flite's Flite Streak, and then later refined the presentation with a series of Skylarks I built in the late 1960s. I also had an Excalibur that in my opinion flew better than most flapped stunt models. It was relatively light for its large wing (600 square inches), 32 Ounces, and had fixed flaps.

Last edited by The Kiwi; Mar 06, 2013 at 09:26 PM.
Mar 05, 2013, 12:32 PM
Registered User
Flaps help to fly square corners.
Resultant drag slows down the model though. Never a free lunch.
Shoestrings somehow always seemed/needed to be yellow .. even my geriatric one is.
Mar 05, 2013, 01:52 PM
Registered User
RknRusty's Avatar
Mine is geriatric, built decades ago by another modeler. Hopefully I've lightened it and rejuvenated it, but I just couldn't do yeller. If it flies as well as the last couple of models I've built I'll be happy.
Mar 05, 2013, 02:43 PM
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Traian's Avatar
Your model will do fine in the pattern and if it does not corner see if you can push the CG back a litle at a time. Get and adjustable handle.
Mar 05, 2013, 07:51 PM
Registered User
With out flaps, CL planes tend to fly egg shaped loops, rounder at the bottom and pointy at the top. IMO, flaps allow you to fly prettier, rounder loops. And if you set up a plane the way I do with outrageous amounts of control surface movement, it allows smaller loops, and radically tight turns that look really cool when doing a square 8 or an hour glass from 5 feet to 45 degrees, pulling out of a dive or turning into a vertical climb.
Last edited by tigreflyer; Mar 05, 2013 at 07:59 PM.
Mar 05, 2013, 08:33 PM
Registered User
More important than flaps is putting a hot iron to that bird before flying and pulling out the warps and hoo hoos. Perhaps the bitchinist flying profile plane with out flaps I've ever seen was a Shoestring with a balloon tank.
Last edited by tigreflyer; Mar 05, 2013 at 09:25 PM.
Mar 05, 2013, 09:33 PM
Registered User
RknRusty's Avatar
I don't remember if I mentioned it anywhere at RCG, but since I don't want to pay Brodak $9 bucks to ship me a $9 dollar tank, a 2 or 3oz party balloon is most likely going to be the fuel supply for my maiden excursion. I used to feed the Medallion on my Li'l Jumpin' Bean with a balloon. That was before I discovered the joys of pressure bladders and fine thread NVs for my 1/2As. Now that's all I use on them.

Here's a balloon on another of my toy planes:
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That plane IS a flap.
Last edited by RknRusty; Mar 05, 2013 at 11:22 PM.
Mar 06, 2013, 12:19 AM
Registered User
downunder's Avatar
Quite some time ago I built an own design and put everything I could think of in it to help do the pattern. One of the features was a fully adjustable control system. First flights were with the flaps set to zero throw (essentially an unflapped model) and elevator at around 25-30 degrees each way. First flight showed very tight corners but too sensitive so I backed off the elevator throw until I was comfortable. Final elevator movement was 17 degrees but corners were just as tight as before. It's only problem was a very slight stall, particularly the last corner of the hourglass, so I started adding flap movement until all trace of stall was gone. As Bare mentioned, flaps slow the model down right where you don't want it slowing (hard corners) so I was aiming for the least amount of flap possible. The end result was just 5 degrees up and down. What really surprised me was that adding this very small flap movement increased the load at the handle by a guesstimate of 2-3 times what it needed without flaps.

Don't use my figures for your own model because it's going to vary from model to model but I strongly recommend a fully adjustable control system for a serious stunter. I got away with mine because of a very low wing loading (59ounce with 810sq inch) and tail moment of 21.5" hinge to hinge. And a bog standard G51 in a full 4 stroke.
Mar 06, 2013, 09:06 AM
Registered User
I've designed and flown several 1/2A stunt models with flaps, and came to the conclusion that they flew better with no more than 10 degrees either way. I think the drag factor is perhaps more noticeable on a 1/2A than a bigger airplane.
Mar 06, 2013, 11:45 AM
Registered User
RknRusty's Avatar
Downunder, I'm way behind you, elementary on the learning curve, so I feel better now starting without flaps. I have a ways to go before I could take advantage of what they would add to my flying. Same goes for Jim too, though I do handle a 1/2A plane pretty confidently. I might be ready to fly my first larger plane this Sunday.
She's looking really good with all the decals on it now. Hopefully I won't ugly her up the first time out.
Mar 06, 2013, 08:48 PM
Registered User
Jim Kraft's Avatar
I flew a friends Shoestring last summer with a Fox 35 on it, and it was one of the nicest planes I have flown. It grooved very well and I really enjoyed the flight.

I have built four Midwest Magicians all with moveable flaps. I built them exactly the same as the plans and found when I started flying the first one that it did not turn well balanced at the point on the plans. I moved the balance point back an 1" and it flew great. I am sure it would fly well at the CG shown on the plans if I had built them with fixed flaps. All of my scratch built Magicians weighed between 35 and 38 ounces. The first one was powered with a Fox 35, and the other three were powered with McCoy 40 Red Heads. The Magician is a really nice flying plane with no bad habbits. Guess that is why I have built four of them.
Mar 06, 2013, 09:47 PM
Registered User
Yea, but tell us the difference between how it flys with Fox .35 vs The McCoy Red Head .40s! Now here is a study!
Mar 07, 2013, 12:45 PM
Registered User
Jim Kraft's Avatar
It flew pretty well with the Fox. The McCoy 40 is a very unique engine, and has one of the best stunt runs of any of the engines that I have flown. I use an APC 12-6 cut to 11", and it loves that prop. It does most of the pattern in a four stroke, just beeping into a two at the tops of manuevers. It seems to have alot of torque which makes the plane very easy to fly even in the wind. It runs best on 5% nitro fuel with at least 25% oil with the biggest part castor. I usually use all castor with a little Klotz thrown in to keep it clean.
Mar 07, 2013, 07:16 PM
Registered User
Great answer! I have a primo Red Head 40 that I want to try on my Brodak 40 that currently has an OS Max S 35 mounted. I bought that McCoy for around $5 or $6, NOS from our regular salesman who serviced Ca Model Supply in '75.
Last edited by tigreflyer; Mar 07, 2013 at 07:39 PM.

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