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Old May 13, 2012, 10:10 AM
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The Merry Miller

Hi all,

I came across the plans for a vintage ff autogyro called the Merry Miller over on the vintage forum and I am considering building an electrified (and R/C) version. It looks quite different to the autogyros I have flown so far:

There is almost no downthrust.

The mast angle is rather small (ca 5 degs according to my eyes).

The horizontal stab is lifting and the CG is behind the mast (!).

The rotor blades are built up with ribs and spars and have a comparatively large chord (over 3").

So I am interested, especially in the large-chord rotor blades. I'd like to rebuild my deceased Cierva C.6, but I would like to do it in a more scale way (yes, I know you cannot see the blades when the plane is flying, but most of the time planes aren't).

I am also interested in how much power this one would need and the construction lends itself to be a test-bed.

So here are the changes I am considering:

- build a moving rudder
- build the horizontal stab in two parts as elevons (I prefer ailerons to DC for roll control)
- use a bb gearbox for the rotor (I like these detachable rotor blades, though)
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Old May 13, 2012, 10:12 AM
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Here is what the plans look like. Now what do you think?
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Old May 13, 2012, 08:59 PM
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G'Day Edi
Looks as if you could have an interesting project on your hands.......Good Luck...
Chris............
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Old May 15, 2012, 01:28 PM
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So many helpful replies! Well, let's go, then!
Meanwhile I've found out that the gyro was powered by an Allbon Merlin which had an output of a meagre 43W! This *will* be interesting.

One of my hypothesis is that this might be due to the large-chord rotor. I guess you need more energy to spin the rotor fast and finally, all the energy - however transformed - comes from the powerplant. I will have significantly more weight to carry (about 3 oz. at least), but I will have a ball bearing in the rotor mast which should reduced friction compared to the original.

There are many interesting design features I have found only today while perusing the plans. (I have a nasty cold with headache, sore throat and whatever else you like, so sitting and looking at plans is one of the few things possible to do for me.)

About eight years ago, I purchased my first kits from aerodromerc.com and I was thrilled - they were so nicely designed, laser-cut (my first ones) and flew so well! I was allowed to do several prototype builds and I even managed to talk Kay into a few projects. Yes, I was pampered! Today I cut my first balsa formers since ... I don't know when. Quite an achievement for me ... and fun! Here is what I got so far:
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Old May 15, 2012, 02:38 PM
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I can only reach my workshop (which is in the attic) through my son's room, and since he is in bed now, there will be no more building today. The fuselage is put together, and the lines are very nice and sleek. BTW, this is my first vintage plane.

I built it according to the instructions, so I glued formers 2-6 onto the side, glued on the other side, clamped the ends together and inserted the other formers. As you can see, the fuselage has turned out perfectly straight - well, for a given tolerance, of course ...
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Old May 15, 2012, 03:51 PM
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EDI,
I also have this plan so I'm watching with great interest. One of the older gents in our club constructed one of these and could never get it to fly in its original free flight format.
But I see no reason why it can't work as an RC model with some adjustments to the mast and CG position.

Regards

Rich
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Old May 15, 2012, 04:05 PM
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Quote:
Originally Posted by SafeLandings View Post
EDI,
I also have this plan so I'm watching with great interest. One of the older gents in our club constructed one of these and could never get it to fly in its original free flight format.
Thanks for the motivation

Quote:
Originally Posted by SafeLandings View Post
But I see no reason why it can't work as an RC model with some adjustments to the mast and CG position.
Which is exactly what I do *not* want to do. I am sure it could fly in the original configuration and I want to keep as close to it as possible. But I want to go electric and I do not want to run for miles to collect my plane.
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Old May 15, 2012, 04:59 PM
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And I just came across the "Gyro Skipper" plans, another ff autogyro with the same basic configuration as the MM - lifting stab and CG behind the mast. Maybe this is better for hands-off landing.

One difference between the Gyro Skipper and the Merry Miller is the 4-blade rotor as opposed to the three-blade one of the MM. Maybe I should go for four blades to counter the additional weight? I also like the fact that 4-blade rotors are easier to balance and build ...
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Old May 16, 2012, 05:28 PM
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A few more things: a few bits of sheeting on the fuselage and the rough construction of the horizontal stab (will cut off the elevator later) and the rotor blades (I have decided I want four of them). All this together weighs 49g, no idea whether this is good or bad.

The motor you see in front of it is a Kontronik Dancer. I have it for eight years now. It was first installed in a Kavan Sopwith Triplane, it has powered my Bleriot, but it has failed to get my Cierva C.6 airborne (needed a stronger motor there), so this is an interesting possibility of comparing numbers. Anyway I am sure it will output much more than the Allbon Merlin.
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Old May 16, 2012, 10:34 PM
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Edi,
I've watched you build thru other forums....so I watch with interest! Built up wings....this should be fun! You are doing an excellent job and many of us are interested......but few of us have built this model! You might be starting a trend!
Thanks for a great build!
Joe
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Old May 17, 2012, 05:11 AM
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Thanks Joe,

since you are a top-notch builder and autogyro expert this means a lot to me. How I can live up to the expectations ...
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Old May 17, 2012, 02:48 PM
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Well, I'll try somehow

Here is what I did today: Finished the horizontal stab and the rotor blades, built the rudder. Some minor jobs and then it's covering time ... Of course, the original was covered with tissue paper, but I won't do that, I think. I have several rolls of SolarFilm (I guess that's the name) that's the stuff I have covered the Avro Baby with. It's very glossy, so aerodynamics will be somewhat different than with tissue or polyspan. Of course, normally you want your blades as glossy as possible but what is normal with this bird?

It is 160g now, and missing is:
- covering
- rotor mast
- landing gear
- rc stuff
- battery pack

The battery pack is 100g, and I hope I can stay below 400g.
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Old May 17, 2012, 11:42 PM
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Dude....that looks great! How refreshing to see something else out here!

I love this old timer stuff.....keep up the good work!
Can't wait to see it covered!
Joe
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Old May 18, 2012, 09:32 AM
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Rotor blades are covered with red Nelson (had to look up my Avro Baby thread to find the brand - quite some time since I covered something), looks nice. Covered and assembled rotor weighs 65g, that's about half of the weight of my Cierva's rotor.

I took it out for a first spin-up and rpm went up like crazy, but not yet real autorotation. (Well, I went out on my roof and the wind direction kept changing.) Might be a bit too much negative incidence. But rpm goes done very fast, too. We'll see what this means in the air - these blades do have the same area as a pair of wings, even when standing still, and after all, that's why I am doing these experiments in the first place: to find things out nobody else wants to know.

I hope to post some pictures over the weekend.
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Old May 19, 2012, 08:59 AM
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Hey Edi,
I'm more curious on how those blades flex? I'm assuming the rubberband has something to do with it. Can you show how it works with some pictures?
Joe
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