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Old Apr 12, 2008, 04:11 AM
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DJ Aerotech Chrysalis 2M MkII Build Thread 2008

Yup. Froggies next bird.

Garage cleaned, instructions on the wall and fuselage framed up. Gotta say Mr. Stackhouse did a killer job putting this kit together. Laser cut parts are the BEST!

What really attracted me to the Chrysalis was the wing. Just a gorgeous shape. I'm really looking forward to finishing this sleek 2M RES bird.

Stay tuned...
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Old Apr 12, 2008, 05:10 AM
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Ok...off to bed. This thing practically builds itself!
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Old Apr 12, 2008, 06:40 AM
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Looks great so far!
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Old Apr 12, 2008, 12:48 PM
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Great choice, looking forward to it. My first build was a Chrysalis HLG, terrific learning experience and flys great too. I heard the 2 metre is even easier to build.

Tom
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Old Apr 12, 2008, 01:24 PM
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Originally Posted by tw126a
Great choice, looking forward to it. My first build was a Chrysalis HLG, terrific learning experience and flys great too. I heard the 2 metre is even easier to build.

Tom
Yeah...I had the fuse together in about 3 hours.

It occurred to me that this plane has a really unique profile. I really dig the 'squashed' fuselage profile. It reminds me of a lemon shark.
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Old Apr 12, 2008, 03:47 PM
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The Chrysalis is defiantly among the best looking wood planes around.
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Old Apr 12, 2008, 07:51 PM
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Update:

Sanded and faired in the bottom ply 'skid-plate.'

Broke hatch free and installed light-ply retention tongue.

Installed Sullivan Golden Cable™ cable guides.

Installed basswood support to help with higher than normal launch loads.


To Do:

Sheet remainder of fuse. Glass forward bottom portion of fuse. Glass wing-box area. Glass forward compartment floor to 1/2 way up the sides.

Not concerned about weight, especially since I'd rather add some forward weight in the form of added strength as opposed to just lead shot.

I'm really enjoying this build.

-Sean
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Old Apr 12, 2008, 07:56 PM
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Quote:
Originally Posted by Don Stackhouse
Looks great so far!
Don,

With a little added glass in the forward section and a carbon laminated / kevlar wrapped main spar, do you think this bird will take a launch from a NSP Pinnacle large histart? I launch my 3M Marauder off of one.
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Old Apr 13, 2008, 08:38 AM
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Quote:
Originally Posted by FrogChief
Don,

With a little added glass in the forward section and a carbon laminated / kevlar wrapped main spar, do you think this bird will take a launch from a NSP Pinnacle large histart? I launch my 3M Marauder off of one.
I'm not having much luck verifying the rubber diameter on that particular Hi-start, but if it's what I think it is, it should do fine built stock, without adding any of that extra reinforcement. I'm not sure where you came up with the need for all that extra glass.

I launch mine with no extra reinforcement from a Hi-start that uses 3/8" rubber. I've also bungee launched it (high speed horizontal launch, then pull up to convert the speed into about 150-200 ft of altitude) from a bungee using that same 30 feet of 3/8" rubber plus another 30 feet of towline, with no carbon in the spars and only the 1" fiberglass straps on the fuselage shown in the instructions.

The plane is designed for Hi-starts and will also winch launch fine, without carbon in the wings, if you use a gentle foot on the pedal. The problem comes in when you are winching in gusty conditions. A winch line has very little "give" in comparison to a Hi-start, so a sudden gust can put a massive load on the wings. That's where adding carbon to the spars comes in.

A comment about winch launching: Folks winch launch planes like the Gentle Lady, with or without carbon added to the spars. They often watch how far the wings flex to judge the amount of line tension they're carrying. The stock wooden spars on the Chrysalis are approximately five times stronger than those on the G.L., but they are also that much stiffer. When folks try to flex the wings on a Chrysalis as far as they are used to seeing on their G.L., they can get into trouble. We sell a lot of these in Australia where they are generally very used to winching wooden sailplanes, and they do it with no trouble. OTOH, Americans as a group seem to have heavier pedal feet, are used to all-composite airplanes with carbon spars that can take anything you throw at them, and tend to have more problems when they winch wooden airplanes. A little common sense and finesse in your technique avoids a lot of trouble. That goes for any wooden sailplane, not just this one.

Summary:
Adding carbon to the spars is necessary if you plan to winch launch, but optional for Hi-starting. Adding carbon to the tails is optional for winch launching.

As far as adding glass to the nose and middle of the fuselage, the local reinforcements called for on the plans cover what's needed there. Adding a bunch of extra glass may or may not help in lawn-dart landings, depending on where you put it. Actually, the highest stresses are on top of the fuselage nose in those cases, when the upward and aft loads from the impact try to spread the top edges of the fuselage apart, which then tries to split the top of the nose ahead of the hatch. That's the reason for the glass tape across the top of the nose at that location.

Adding extra structure in the forward fuselage will not help C/G significantly, at least not as much for the same weight as adding ballast concentrated in the end of the nose. The further ahead of the C/G you add the weight, the less you need to accomplish the same C/G shift. In any case, if you build the airplane well and don't use too much glue in the tail, and keep all your radio gear well forward, you should need little or no nose ballast to set the C/G properly.

As far as flying qualities goes, the plane actualy flies best with the C/G near the aft limit shown on the plans.

The good news is that although your extra glass in the fuselage really isn't necessary, it isn't really going to hurt significantly either. The carbon in the wings is a good idea, it gives you the option of winch launching (with common sense, I still wouldn't inflict a pedal-to-the-metal abusive launch on it) if the opportunity comes up.
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Old Apr 13, 2008, 11:54 AM
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Quote:
Originally Posted by Don Stackhouse
I'm not having much luck verifying the rubber diameter on that particular Hi-start, but if it's what I think it is, it should do fine built stock, without adding any of that extra reinforcement. I'm not sure where you came up with the need for all that extra glass.

I launch mine with no extra reinforcement from a Hi-start that uses 3/8" rubber. I've also bungee launched it (high speed horizontal launch, then pull up to convert the speed into about 150-200 ft of altitude) from a bungee using that same 30 feet of 3/8" rubber plus another 30 feet of towline, with no carbon in the spars and only the 1" fiberglass straps on the fuselage shown in the instructions.

The plane is designed for Hi-starts and will also winch launch fine, without carbon in the wings, if you use a gentle foot on the pedal. The problem comes in when you are winching in gusty conditions. A winch line has very little "give" in comparison to a Hi-start, so a sudden gust can put a massive load on the wings. That's where adding carbon to the spars comes in.

A comment about winch launching: Folks winch launch planes like the Gentle Lady, with or without carbon added to the spars. They often watch how far the wings flex to judge the amount of line tension they're carrying. The stock wooden spars on the Chrysalis are approximately five times stronger than those on the G.L., but they are also that much stiffer. When folks try to flex the wings on a Chrysalis as far as they are used to seeing on their G.L., they can get into trouble. We sell a lot of these in Australia where they are generally very used to winching wooden sailplanes, and they do it with no trouble. OTOH, Americans as a group seem to have heavier pedal feet, are used to all-composite airplanes with carbon spars that can take anything you throw at them, and tend to have more problems when they winch wooden airplanes. A little common sense and finesse in your technique avoids a lot of trouble. That goes for any wooden sailplane, not just this one.

Summary:
Adding carbon to the spars is necessary if you plan to winch launch, but optional for Hi-starting. Adding carbon to the tails is optional for winch launching.

As far as adding glass to the nose and middle of the fuselage, the local reinforcements called for on the plans cover what's needed there. Adding a bunch of extra glass may or may not help in lawn-dart landings, depending on where you put it. Actually, the highest stresses are on top of the fuselage nose in those cases, when the upward and aft loads from the impact try to spread the top edges of the fuselage apart, which then tries to split the top of the nose ahead of the hatch. That's the reason for the glass tape across the top of the nose at that location.

Adding extra structure in the forward fuselage will not help C/G significantly, at least not as much for the same weight as adding ballast concentrated in the end of the nose. The further ahead of the C/G you add the weight, the less you need to accomplish the same C/G shift. In any case, if you build the airplane well and don't use too much glue in the tail, and keep all your radio gear well forward, you should need little or no nose ballast to set the C/G properly.

As far as flying qualities goes, the plane actualy flies best with the C/G near the aft limit shown on the plans.

The good news is that although your extra glass in the fuselage really isn't necessary, it isn't really going to hurt significantly either. The carbon in the wings is a good idea, it gives you the option of winch launching (with common sense, I still wouldn't inflict a pedal-to-the-metal abusive launch on it) if the opportunity comes up.
Don,

Thanks a bunch for the detailed reply. To clarify, I'm only gonna be adding a single layer of very light glass to the forward fuselage. All up additional weight should only be around 1/8th ounce. I'm gonna add the carbon to the wing, if only because it's such an easy thing to do with almost zero weight penalty.

Have a great Sunday.

-Sean
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Old Apr 16, 2008, 01:51 AM
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Progress:

Fuse glassed (forward section)

More tomorrow. Pics soon!
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Old Apr 16, 2008, 02:18 AM
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Decided on my color scheme.
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Old Apr 16, 2008, 02:36 AM
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Froggy, I would make the top and the bottom a little more different.

I once had a plane that had fairly similar designs top and bottom and it made it really hard to tell which way was up, as the colours tend to go black at distance.

....so much so I got lost in the middle of a roll and decked at full power.

after that I made sure to never repeat the mistake.
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Old Apr 16, 2008, 02:45 AM
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Originally Posted by Curare
Froggy, I would make the top and the bottom a little more different.

I once had a plane that had fairly similar designs top and bottom and it made it really hard to tell which way was up, as the colours tend to go black at distance.

....so much so I got lost in the middle of a roll and decked at full power.

after that I made sure to never repeat the mistake.

I'm gonna tweak it. How about this?
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Old Apr 16, 2008, 08:17 AM
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General practice is a very dark color on the bottom and a very light color on top, but with some contrasting trim at least on top.

In flight you are generally viewing the bottom of the plane against a background of relatively bright sky, hence the dark color.

When you see the top in flight, it's usually in situations such as the turn to final approach on landing, often with things like dark trees in the background, hence the light color. However, when you are viewing the top, the variety of backgrounds is greater, so a mix of light and dark is usually a good idea.

Also, viewing the top usually occurs with the plane closer to you, so patterns are more discernable.

When your vision is challenged while viewing the bottom, it's usually because the airplane is a tiny speck, way high up in a thermal. At that point you need all the "visual footprint" you can get, and patterns tend to just break up the shape and make it harder to see. That's why the competition flyers usually opt for a solid dark color (usually black) on the bottom. Also, the chordwise dimension is the smallest in that visual footprint (compared to the span), so it's good to go with patterns that don't break up the chord, at least on the bottom.

That's also one of the big reasons we opted for the low aspect ratio wing and low drag airfoils philosophy for the Chrysalis series, it maximizes wing chord, making it easier for old or inexperienced eyes to see. On more hard-core competition ships like our Spectre series we opted for higher aspect ratio planforms and special airfoils that were optimized for that approach.

At a distance and/or in poor lighting you will tend to lose perception of color, and just see the light/dark pattern. Red and white bands could look just like black and red bands under those conditions. For that reason, a totally different pattern between top and bottom is helpful.

The other thing to remember is that everyone's eyes are different. What golf balls or tennis balls are easier for you to see? White? Green? Yellow? As far as dark colors go, black is pretty standard, but dark red is almost as good. Dark blue may be OK, but for some folks that fades into blue sky too easily.

When you've narrowed it down to a few candidates, making scaled cardboard cutouts that you can view against a variety of backgrounds (sky blue, light or medium gray, dark green) can be useful. Note, in these tests you should look at an image that shows the entire bottom scheme, or the entire top scheme, not half and half.

You might be able to just change the background color in your paint program and try viewing your computer screen from a distance. Colors turn gray in the distance, so you might also want to turn down the brightness and contrast on your monitor a little bit. The size of the image on your screen is proportional to the distance things equate to. For example, if you scale your model's picture to about 3/4" span on your computer screen, that's about one hundreth the span of the full size model, so viewing that from about 30 feet away is about like viewing the model from 3000 feet away.
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