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Old Aug 26, 2009, 02:47 PM
Rotozuk's Avatar
United States, CA, Novato
Joined Sep 2003
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Build Log
Re-Build Log - Vintage Slegers Skyhawk - 3 Meter Thermal

Thought I'd share a rebuild of a classic old plane I recently picked up from another RCgrouper.

I don't know much about the Skyhawk, but she has some nice lines, 3 meter wing span, full house glider. After searching I discovered Brian Agnew here on RC Groups was offering an updated version of this classic. Through emails with Brian I understand Mark Allen designed the original Skyhawk. It seems to have come in a few different wing configurations over the years. Mine is a multi-tapered version that I have seen one other photo of, so I know there was more then just mine with this setup. Hope others can fill in the blanks for me.

She has a rather flat bottom airfoil, not sure what it is just yet. Nice sized flaps, and all surfaces look nice and large. She has the bones of a nice thermal ship. I did read in an old post about a tattered Skyhawk taking abuse off winch launches with no issues. That is encouraging as the carbon rod that joins the wings seemed pretty short.

Onto my purchase...
I thought I was buying a flight ready plane with a single patch to the wing. What I got was a bit of a surprise. I'll let the photos speak for themselves.

Maybe I'm picky, but I feel this plane will need a total rebuild. And while I'm at it I'll be adding a motor to her. I had hoped to power her with a cheap outrunner to save some cash after paying to much for the airframe, but the tiny nose of this plane is forcing me into 30mm or smaller motors, and I just don't want to deal with a 200 watt outrunner on this sized plane. So probably going to run a simple and reliable Multiplex 4G with a 4.4:1 gearing. Still working on my options.

I've started stripping her down and tested the servos. Will only be keeping the flap servos as the rest are worn out and sloppy. Been having fun grinding out the well glued in lead shot that filled the nose area. Also grinding the gobs of epoxy and CA that attempted to hold the canopy mounting wire.

God I love grinding CA.. I love how it burns the lungs and closes your eyes... Good times.

Hope to keep her weight below 2 kg even with the weight of electrics. Thought this may be tough with an inrunner taking up so much nose space, I wont be able to shove the battery as far forward. As best as I can tell she was around 1.962 kg in glider form. (Each wing panel was within 1 gram of each other.) That should result in a much better thermal plane then my current 3 meter Condor that weighs about 2.9 kg and has less wing area.

Should be fun when I'm done. I'll try and post more pics as things progress.

-Wayne
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Last edited by Rotozuk; Sep 01, 2009 at 12:37 AM.
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Old Aug 27, 2009, 06:10 AM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
I'm with you - needs to be stripped down and rebuilt. I've bought several models that way, but it's fun to do..
..a
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Old Aug 29, 2009, 02:07 AM
Rotozuk's Avatar
United States, CA, Novato
Joined Sep 2003
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Been a busy week, but got some time invested in pulling her apart and cleaning her up. Good news is the fuse appears to be in very good condition.

Ordered up the Mutliplex 480-4G with 4.4:1 gear box. Should power her just fine on 3S.

Wet sanded on the Sky Hawk and my good ol' Filip fuses until my fingers were bleeding today. Then filled the low spots with some filler putty. Will sand that off as soon as my fingers are able.

Question:
What the heck holds the wings together on this plane? Just friction? There is just a carbon spar, and an alignment pin near the trailing edge. There is no method to lock the wings from slipping out. No collars, no screws, no rubber bands and no spring. So tape to the fuse??

-Wayne
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Last edited by Rotozuk; Aug 29, 2009 at 02:26 AM.
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Old Aug 31, 2009, 01:16 AM
Rotozuk's Avatar
United States, CA, Novato
Joined Sep 2003
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Little more progress on the glass parts. Sanded the filler putty down. Fuse is looking really good now. So much for the easy job.. Now onto the harder parts.
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Old Sep 01, 2009, 01:27 AM
Rotozuk's Avatar
United States, CA, Novato
Joined Sep 2003
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You got to love RC Groups.. The second owner just got in contact with me.. That makes me the 4th owner of this plane. Hopefully he will share a little more info about the plane for all of us.


Started working on the horizontal stab and elevator today. Basically just sanding and clean up. Managed to reduce some weight from the parts, but not much, maybe a 1/4 of an oz. I think this plane is going to be tail heavy, so any tail weight saved is a good thing. I'm debating what I'm going to do for rudder control. Old layout had a full size servo in the nose. I'm debating a servo in the nose, or a servo in the tail. Either method probably has about the same weight penalties depending on pushrods. Rather not do a pull-pull even though it would be best for weight. hmm...

Probably start grinding the last of the lead next and work on the firewall install. Ordered up some 3S 3000 batteries today. Depending on weight needed I'll either fly a single 3000, or combine to make 6000. Also bought a nice little 2S lipo and a 3 amp (5 amp surge) switching voltage regulator. I think 3 amps should be ok for the 6 mini servos as they should not see much load on this plane...? Thoughts?

-Wayne
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Old Sep 01, 2009, 07:59 PM
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Santa Rosa, Northern CA, USA
Joined Oct 1999
2,472 Posts
Hi Wayne,

A few answers for you.

Airfoil is most likely a 7012. It was the "new" foil at the time.

Also, tape, chord wise, 1/2 on top of the fuse and 1/2 on wing to secure them. Electrical tape works well - and you can get it in colors some places.

Pretty sure I still have the video of Mark introducing the Skyhawk - filmed on our local hill.

They were fairly sweet flying when trimmed out correctly. Not as nice as the Thermal Eagle (RG 15) or Falcon 880 (3021 version). I think you will have fun with it

Dave
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Old Sep 02, 2009, 01:16 AM
Rotozuk's Avatar
United States, CA, Novato
Joined Sep 2003
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Quote:
Originally Posted by Daveairway
Hi Wayne,

A few answers for you.

Airfoil is most likely a 7012. It was the "new" foil at the time.

Also, tape, chord wise, 1/2 on top of the fuse and 1/2 on wing to secure them. Electrical tape works well - and you can get it in colors some places.

Pretty sure I still have the video of Mark introducing the Skyhawk - filmed on our local hill.

They were fairly sweet flying when trimmed out correctly. Not as nice as the Thermal Eagle (RG 15) or Falcon 880 (3021 version). I think you will have fun with it

Dave
Dave,

Thanks for the info!

According to the old 2004 ad for this plane it has a 7037 airfoil:
Quote:
For sale 118 inch obeechi 7037 airfoil. I haven't flown competition in 6-7 yrs so I've decided to sell my competition ships. Weighs about 70 oz's. Overall good shape,a few dings, scratches. It had a mid-air, on the left wing, its repaired, and been flown 30-40 flts. The repair,doesn't involve the spar, you can see on the photo, it's just an inch or so of the leading edge out towards the tip of the wing.
Reading old posts about other Slegers it sounds like airfoils and sometimes wing spans and planforms changed to stay competitive or to meet customers requests.

It appears that my plane was originally kitted back around 1995.
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Old Sep 05, 2009, 11:30 PM
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United States, CA, Novato
Joined Sep 2003
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Got some other birds up and flying, so now more time to work on this one. Not a lot of progress. Just some more sanding and cleaned the gunk out of the nose area so I can start fitting my firewall. I hope I never need to grind glue and lead again!

-Wayne
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Old Sep 10, 2009, 05:40 PM
Rotozuk's Avatar
United States, CA, Novato
Joined Sep 2003
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Got a bit more work in on this project. Firewall is cut out and test fit. The oblong fuse takes very well to the round motor mount, thus a spinner should fit nicely.

Decided to open up the rudder to check for damage and convert it to a conventional control horn. No surprises, but I went ahead and sanded it down some for a little better fit to the airframe and reduce a bit of tail weight. Then covered it in some white Monokote. Yep, I still suck at using Monokote. (I like Ultra and Ora better.)

Got my batteries in. Some 3S3000 Flightmax for about $20 each. I should have payed closer attention to the cell demnsions as these are a rather odd size, tall and wide. I can only fit one in the fuse at a time. But that is fine.. I use the same motor in a smaller plane at around 300 watts and rarely use more then a 1000 mah per flight even when playing around a bunch with the power on. The Skyhawk will be pushing the motor harder, but still should be fine. The radio will be powered by a 2S1000 via a 5 amp max switching voltage regulator. Should be enough for many hours of flight.

More soon..

-Wayne
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Old Oct 08, 2009, 01:17 AM
Rotozuk's Avatar
United States, CA, Novato
Joined Sep 2003
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Been working on some other projects as I was stumped on locating a spinner for the plane. Well, I finally found a nice 32mm spinner for a 4mm shaft. Decided to try something a little different on this plane. Since I was going after an odd ball spinner, why not a real odd ball? Europe to the rescue.

Hope to get back to the project soon.

-Wayne
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