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Giant Astro Hog Laser Cut Kit - Jerry Bates

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Giant Astro Hog Laser Cut Kit - Jerry Bates

Old 08-12-2020, 04:19 AM
  #26  
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Originally Posted by erans View Post
Bob - I will probably be using the MVVS 40 IFS (40cc), but also have a DLE 35RA on the shelf if I will think it will be a better option. The plans call for the Quadra Q35.
Great choice, I will be following your progress and thanks for you input.

Bob
Old 08-13-2020, 03:42 AM
  #27  
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I sanded the wing-tips shear-webs and spars to shape and started to shear-web the "rear spar".




Cheers,
Eran
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Old 08-13-2020, 04:34 AM
  #28  
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Eran, looks good so far.
Let me throw a few thoughts at you since it seems like I'm always reinventing what ever I build. I was looking at the wing tips and reading your comment about them. That had me wondering the following:
1)Why not use 2 or 3mm birch ply instead of lite ply for that rib? It would be stronger, less flexible and wouldn't add much weight
2) I'm thinking, with the multipiece round outer frame that I would have replaced one layer of balsa with ply and made that layer all one piece. You thoughts on that one?
3) You said you couldn't bend the spars enough while using either spruce or balsa. Again, why not make the spars from ply and sand to final shape after installing them?
On a non-aircraft note, I was in Perth/Freemantle back in 1984. I can only assume the area has changed but I am curious. There was a place called Pinocchio's that, if I remember correctly, was a disco. Had a wall that was all video screens, a wood dance floor and a bar that had to be at least 10 meters long. Do you know what happened to the place? Is the building still there or has it been replaced with something else by now?
Old 08-13-2020, 05:14 AM
  #29  
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Hydro Junkie - There are many ways to skin a cat. Also I have been in the hobby for a while, I am always learning from new ideas as well as I hope that others find some of my ideas helpful.
1. Why not use 2 or 3mm birch ply instead of lite ply for that rib? - At the time, my concern was adding unnecessary weight at the wing tips. The surface to surface strength was not a big consideration as I will probably have to insert a load bearing component ("wing tube") to pass the heavy model certification. I have ordered a CF tube (with fibreglass sleeve) and am waiting on shipment (which can take a while these days).
2. I would have replaced one layer of balsa with ply and made that layer all one piece - Since I got these parts in the laser cut kit anyway and the building technique match the plan, I saw no reason to change it. The good thing in the way it was design is that the grain direction is corresponding correctly to each piece in case of impact. In addition, being 19mm thick, a single layer will be 9.5mm which is a very thick and heavy ply.
3. Why not make the spars from ply and sand to final shape after installing them? - Strength wise, there is no issue with using balsa spar on this section (which has shear-web on both spars) and you get the weight saving. In addition, I will have the "wing tube" which will carry the load anyway. Plywood will add weight at the wing-tip on top of the additional weight I am already adding. I will keep this idea for similar cases : )

The old Pinocchio's (393 Murray Street, Perth) is now Magnet House (called "Maggie’s") and is still a night club (to the best of my knowledge).

Cheers,
Eran
Old 08-13-2020, 11:45 AM
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I like it, a fast and informative response. There was a few things I didn't know about the build so, with that said:
  • I was thinking the tip was in the 10-12cm range when you made the comment about being too flexible. My thought was ply, with lightening holes, might be a better option
  • I didn't realize the arch was 19mm thick. I still like the idea of a piece of ply in the structure but I'd go with a piece of 1.5 or 2mm sandwiched in the middle instead
  • I see your point on the built up spar, not really a reason to change it.
Here in the US, we don't have a heavy model inspection to deal with so it does make a difference when you have to deal with a weight limit vs red tape issue. I know, with my other hobby of building and racing scale hydroplanes, weight is an issue as well. I build a majority of the boat from 1.5mm birch aircraft grade plywood(the same kind used to make wooden ultralite home built manned aircraft) but some of the framing is 3mm while a couple of frames are 6.5mm, the largest being right at the back of the boat. To cut weight from the heaviest parts, I laminate two pieces of 3mm together, after cutting lightening holes out of the inner piece, saving 30-40% over the solid piece. Where ever possible, I also cut lightening holes out of the thinner ply as well. By the time I'm done, I can usually save a good 40% in weight so I do understand what you're trying to do.
Nice the know the club is still there, even if under a different name. I'd love to make it back to Perth again, just to see how much it's changed over the years. Just wish it wasn't over 10,000Km and 10-15 hours in the air just to get there. Maybe, when this virus crap is over, the wife and I will be able to make it down for a week or two as we have people to visit in New South Wales, Victoria and South Australia. Wouldn't be hard to make it to Perth as well
Old 08-18-2020, 01:44 AM
  #31  
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Making slow progress, I completed the shear-web on both main and secondary spar and sanded it all.
You can see an issue that came up on the secondary spar centre section. It is made out of two spruce sections on each side of the rib. Due to the angle of the spruce sections, there was a gap between the shear-web and the "outer" spruce. I filled the gap with PVA glue.
In addition, I made and glued the blocks for the landing gear mount supporting the upright section, laminating the blocks in opposing grain direction.








Cheers,
Eran
Old 08-18-2020, 03:52 AM
  #32  
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Originally Posted by erans View Post
Making slow progress, I completed the shear-web on both main and secondary spar and sanded it all.
You can see an issue that came up on the secondary spar centre section. It is made out of two spruce sections on each side of the rib. Due to the angle of the spruce sections, there was a gap between the shear-web and the "outer" spruce. I filled the gap with PVA glue.
In addition, I made and glued the blocks for the landing gear mount supporting the upright section, laminating the blocks in opposing grain direction.








Cheers,
Eran
looking good!

Bob
Old 08-25-2020, 10:21 PM
  #33  
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Thank you Bob.
I finally had some time to progress with this build.
I thought that I will build the ailerons today, however, I realised that I am missing some correct size balsa. My current plan for the ailerons is to use CF tube throughout the aileron as a hinge. To do this, I will need to create a hole in all the "A-2" formers. When I was removing the formers supplied by the laser cut kit, I found that they have supplied formers designated as "W-5" with holes in them... There is no reference to these parts in the plans. I guess that a previous client requested it and they have added it to the kit since.
I also realised that I missed a sub-former "W-11'", which I have rectified as seen in the photos.

The CF load bearing "wing-tube" and sleeve for the wing-tips arrived today, so I got into this instead. One side done, one to go. I am using the Hysol Epoxy for the CF to wood joints.









Cheers,
Eran
Old 08-25-2020, 11:41 PM
  #34  
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I don't know if you noticed or not, but that Hysol is almost three years out of date. That said, I doubt it will hurt anything since we use out of date materials all the time for training and testing at work.
Old 08-26-2020, 03:48 AM
  #35  
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Hydro Junkie - I have been using Epoxy that is over 10 years old recently and it is as good as new... I truly think that the expiry date on some products is for marketing purpose (i.e. to get you to buy another one unnecessarily).

Cheers,
Eran
Old 08-26-2020, 04:57 AM
  #36  
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Originally Posted by erans View Post
Hydro Junkie - I have been using Epoxy that is over 10 years old recently and it is as good as new... I truly think that the expiry date on some products is for marketing purpose (i.e. to get you to buy another one unnecessarily).

Cheers,
Eran
Actually, the expiration date on that Hysol is when it starts to lose some of its adhesive properties. If you were to use it on a full sized aircraft, it could be a serious issue. For your application, in this case, GO FOR IT!!!
Old 08-26-2020, 05:20 AM
  #37  
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Hydro Junkie - Gluing the sleeves serves a purpose of stopping them from sliding out (when the wing tip is not in situ). The glue is not used for structural purpose. The load bearing is done by the wood around the sleeve (the ribs).
In addition, lets remind ourselves that this is a model aeroplane, not a man carrying machine which must comply with regulation. In that case, using within date products will be mandatory and complied with.

Cheers,
Eran
Old 08-26-2020, 06:10 AM
  #38  
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And I totally agree with you. If I didn't, knowing how the shelf life dates work, I would have been saying "DON'T USE IT!!!!!!" as soon as I saw it. Since I work in aviation, using things like Hysol has to be with care. That said, there are just some things that work and this is a case that applies to. Only problem with Hysol is it can be heavy unless used with caution. Glue away as I'm looking forward to seeing the results
Old 08-26-2020, 10:26 PM
  #39  
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Couple of photos of the sleeve in place and I have just glued the CF sleeve on the other side.




Cheers,
Eran
Old 08-26-2020, 10:54 PM
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I like it!!!
Old 08-31-2020, 03:08 AM
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I started to build the aileron. Sometime getting the correct size balsa is difficult here, as in this case where the plans call for 3/16" SQ balsa spar. All that was available in the shop was 1/4" x 3/16", so I notched it to fit.








Cheers,
Eran
Old 09-01-2020, 03:00 AM
  #42  
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Preparing the bottom sheeting for the aileron, I cut it to shape and sanded a bevel at the edge. I then glued the structure to it.





Cheers,
Eran
Old 09-01-2020, 06:13 AM
  #43  
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Originally Posted by erans View Post
Preparing the bottom sheeting for the aileron, I cut it to shape and sanded a bevel at the edge. I then glued the structure to it.





Cheers,
Eran
Everything is looking really great!

Bob
Old 09-05-2020, 12:40 AM
  #44  
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I built the second aileron to the same stage as the first one a couple of days ago.
Today I started the process of attaching the curved aileron LE. It is a bit more involved than I expected, with the LE being of a different width (narrower) to the sheeting.



Cheers,
Eran
Old 09-05-2020, 10:59 PM
  #45  
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Hi Eran,you are doing a really good job!
I'm also currently building the Giant Astro Hog based on Jerry Bates' plan. I have already finished the wing and will now start with the tail units. I made a few changes to make the construction a bit easier, especially the leading edge of wing and aileron.

I am a little concerned about the weight. The wings have gotten pretty heavy .

Greetings from Germany
Manfred
Old 09-06-2020, 01:22 AM
  #46  
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Hi Manfred
Thank you for the kind comments.
I must admit that it does seems that the wing is on the heavy side. I think that modern CAD designed "super light construction" ARF aeroplanes spoiled us in recent years. There is a fair wing area to this aeroplane, so it should still be flying well.
I would love to see some photos of your wing and the changes you made (if you are happy to post it here). I am also wondering if you are going to build the vertical fin as designed or supplement it with Balsa construction (which is my intention)?

Cheers,
Eran

Old 09-06-2020, 02:37 AM
  #47  
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Eran, for him to post pictures in this forum, he would need to have over 10 posts. Right now, he has one so he can't. If Manfred could post pictures in another host and post the links in this forum, it would let us see his build, at least until he gets 10 posts here
Old 09-06-2020, 03:55 AM
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Originally Posted by erans View Post
... I am also wondering if you are going to build the vertical fin as designed or supplement it with Balsa construction (which is my intention)?
Eran, I will build the vertical stabilizer in a balsa construction. Today I made a drawing and started to manufacture the components. I have no way of making the vertical fin out of foam as shown on the plan.

And yes, I'm unable to upload Pictures and Links here .... but luckily I can see yours ... .
Old 09-06-2020, 06:55 AM
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Originally Posted by erans View Post
Hi Manfred
Thank you for the kind comments.
I must admit that it does seems that the wing is on the heavy side. I think that modern CAD designed "super light construction" ARF aeroplanes spoiled us in recent years. There is a fair wing area to this aeroplane, so it should still be flying well.
I would love to see some photos of your wing and the changes you made (if you are happy to post it here). I am also wondering if you are going to build the vertical fin as designed or supplement it with Balsa construction (which is my intention)?

Cheers,
Eran

I completely agree that the current trend in ARF construction is making them too light. A bit of a contradiction there as I personally feel that to a certain degree that lighter is always better. In this case the ARFs IMO are designed too light for the materials used making them fragile. An example of this would be a 40% Extra 260 ARF I once had. The wing ribs all has cutouts to save weight. Problem was that those wing ribs would split at the LE and the LE sheeting would then split just in front of the spar. The fix was to add vertical shear webbing between the spar and leading edge. I think the fix added maybe 1/2 pound to the airplane which wasn't noticed at all in flight. Light is great when it doesn't affect the ability to survive flight loads.
Old 09-06-2020, 07:53 AM
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The construction of the Giant Astro Hog is very good. I don't think the construction itself is too heavy. The weight was given by Jerry Bates to be about 16 to 18 lbs. If the plane doesn't get heavier then everything is ok. The problem for me is when it gets heavier than stated because then my engine may be too weak.

The entire wing weighs almost 5 lbs (without servos and without covering and painting) and I'm afraid that the complete model will be heavier than the 18 lbs mentioned.

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