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Old Oct 02, 2011, 04:52 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
At last

Finally got all the cap strips on.

Mounted the stab cradle and I'm working on the rudder mount.

Tom
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Old Oct 04, 2011, 12:31 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Assembly

Stuck it all together on the floor of the wife's sewing room. Looks pretty spiffy.

Weight is 42.5 oz as it sits. That projects to 68 oz AUW finished. The AUW budget is 79 oz. So, I should be able to stay well within it.

The wing, fuse and pod are bolted together. I may make a wing section to replace the pod for testing. That will simplify testing and allow data comparison when the pod is added.

Tom
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Old Oct 04, 2011, 04:16 PM
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Joined Oct 2004
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looks good. It would have been nice if the pod could have been shifted sideways to find the sweet spot for lateral balance, but I guess it would have been hard to achieve structurally. Especially with this sort of lovely built up structure.
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Old Oct 04, 2011, 06:05 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Brandano,

Actually I can. The right wing panel, pod and center wing panel are all strung onto an aluminum tube (Check out posts #42, #43 and #54). So, I can move the pod by simply building a center panel with a different span.

I think I will substitute a wing section for the pod for testing. All I have to do is build an equivalent span (same span as pod) panel using the wing chord and section. I can put it on the spar in place of the pod.


Tom
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Old Oct 06, 2011, 11:00 AM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
The original plan was to cover everything before assembly. That would make for neat joints. But, there was no progress yesterday. I gave it some thought and realized that I am a cut and fit builder. As long as this thing is in pieces it's not moving. So, I slathered on some glue and installed the stab.

I'll worry about covering it later.

Tom
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Old Oct 09, 2011, 12:50 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Installations

Built a battery box up front and installed the ESC, voltage/current sensor and connectors.

Built boxes for the receiver and Attopilot and installed tubes for the antenna and servo cables.

Tom
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Old Oct 14, 2011, 12:16 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Slowed down a bit

The autopilot installation has slowed things down a bit. I have started over a couple of times, but like the way it is coming together now. There are a lot of cable runs. I am going to start with the older Atto v1.8 which complicates things a little. Anyway it's moving.

I did get the servos. They are the size of 9gs but are ball bearing, digital and metal gear. I can put each servo right at the control surface.

Tom
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Old Oct 15, 2011, 02:06 PM
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Joined Nov 2009
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Quote:
Originally Posted by Tom Harper View Post
I get on the Asym kick every couple of years. I get out the BV specs and make a few drawings and never quite make it to balsa. The problem is that there has never been a reason other than the novelty of the design. Well, this time it's different.

I need a model for forward oblique photography. My previous configuration (photo 1) would allow a clear forward view, but the high thrust line and pusher prop caused a number of problems. A conventional layout gives good results for orthogonal photos but the motor and prop get in the way of a forward view.

So, that brings the asym into consideration. I always start with the camera in the pod and the motor in the fuselage. That results in a cumbersome pod. Then I ran across a photo of the initial Blohm und Voss Ha 141-0. It had the motor in the pod - well duh!!

I made a sketch (it always starts with a sketch - photo 2) and ran a spread sheet that allowed for CG calculation using longitudinal and lateral position of components. I treated the center section of the wing, pod and fuselage as a fixed distance of 12.5 inches. The position of the lateral CG is 1/2 half the span. The spread sheet lets me vary the span of each panel.

I'd like to put the Lipos on the CG so I can vary the capacity. The wing panels will mount with plywood blades so they fold back when they hit anything (landing conditions photo 3).

I have a set of ribs I cut with a section Norm Masters kindly designed. The area will be 6 sq ft. Weight 64 ounces. ~11 oz/ sq ft. Microdan 2510 motor with 11x7 folding prop. No gear - hand launch only. Canon S95 camera. Attopilot IMU system.

I think I'll actually build this one.

Tom
How do you set the brakes on your ESC when using a folding prop?
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Old Oct 15, 2011, 03:09 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
I haven't got that far yet.

On the present model I don't bother with the esc brake. The folder is used to avoid damage on landing, so the position has not been considered critical.

Tom
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Old Oct 16, 2011, 03:27 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Mounted the rudder and installed the servos. The servos are flush mounted on the outside to keep things simple and allow for adjustment. May add some fairing later.

Tom
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Old Oct 22, 2011, 05:21 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Moving Along

I have the camera and servos but I am waiting on the new autopilot and the wire for the lead extensions.

Finished the servo installations and the linkages for rudder, elevator and aileron. Cleaned up the receiver and autopilot wiring and made a cover for the autopilot box. I've found it best to get the autopilot working then secure the hatches and leave it alone.

The center hatch needs some final fitting.

Once I get the hatches finished I'll build the camera mount and install some control wiring.

Tom
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Old Oct 23, 2011, 04:04 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Buttoned Down

Fuselage top hatches are finished. I may add some stiffeners inside and will cover the top with woven paper and polycrylic - later.

I can move on to the pod and camera mount.

Tom
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Last edited by Tom Harper; Oct 23, 2011 at 04:39 PM.
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Old Oct 24, 2011, 05:51 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Camera Mount

I opted for a simple arrangement. The camera is mounted on a rectangular plate of 1/8" plywood. The front edge is rounded and fits a groove in the bottom cross member. It is aligned by posts on either side. The rear of the plate rests on an incidence block. I can change the angle by changing blocks or shaving the one that is in place. The plate is held in place by a rubber band that will stretch between the two dowels.

Tom
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Old Oct 25, 2011, 06:53 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
Leads and window

Intended to crimp pins on the long leads. That turned out to be a waste of time. The cheapo crimping tool I got on eBay was useless. I checked out some threads on the DIY forum and it turns out that the real tools cost money and the skill takes time to develop. So, the leads got spliced and soldered. They fit through the soda straw conduits and the two I've done so far work fine.

Installed the window in front of the camera mount. It has good seals all around to keep out fine sand.

Tom
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Old Oct 26, 2011, 12:26 PM
Lift is cheap - Drag sucks
Tom Harper's Avatar
Socorro, NM
Joined Jul 2004
3,613 Posts
It fits!

All of the cable extensions are in and tested. The pitot connectors are in place.

The center assembly fits nicely. It's not quite plug and play, but I've done a lot worse. There is ample finger room to get to the connectors and wing nuts.

The aileron servo and linkage are internal due to the section thickness. The packing tape hinge is temporary. Will use hinge tape after covering.

The servo extensions are long enough to reach the receiver without the autopilot being in the box. But, I'd rather fly with it present to get data on the logger.

Now to finish the hatches and fill some gaps then I'm on the home stretch.

Tom
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