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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 09-06-2020, 08:07 AM
  #51  
speedracerntrixie
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Your equipment selection will have a large affect on final weight. Wheels, tail wheel assembly, battery packs etc. finishing method obviously can get heavy in a hurry as well. Granted an iron on film is not really appropriate for this airplane but there are ways to save weight when painting fabric covering. Knowing that it could turn out heavy unless you start selecting components that will work without adding excess weight is not such a bad place to be.
Old 09-07-2020, 02:57 AM
  #52  
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Originally Posted by Nece View Post
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.
At 18 lbs. your wing loading will be 30 ozs. with a cubed loading of 10. The Reynolds numbers are pretty high so that makes for a nice flying sport plane. At 23 lbs.the wing loading is at 40 ozs. with a cubed loading of 13, moving you nearly into the racing category and now needing a bigger engine as the weight climbs even more, so as Speed has suggested, be carful with the rest of your choices from here moving forward.

Bob

Last edited by sensei; 09-07-2020 at 03:00 AM.
Old 09-07-2020, 03:12 AM
  #53  
erans
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With the ailerons LE glued into place, I checked the fit and it is not far off being satisfactory. Both ailerons move in both directions properly. I then repeated the ailerons fit test with the wing-tip attached to verify that attaching the wing-tips do not create unforeseen issues.
I was not 100% happy with the wing-tips retention, having some minor flex at the TE. I decided to make additional retention by screw towards the TE, similar to the "front" retention. It has resolved the flex.










Cheers,
Eran
Old 09-08-2020, 02:52 AM
  #54  
erans
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I had the opportunity to use my friend shed today (with enough space around the vice) to bend the landing gear.
A decision was made early on in the project to not use the complex bending pattern showing on the plans.
Not showing well in the photo is the fact that the landing gear has the 2 3/8" bend forward.



Cheers,
Eran
Old 09-08-2020, 05:45 PM
  #55  
erans
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I drilled the landing gear blocks and trial fitted the installation and it is perfect.
Next, I decided to tackle the elephant in the room. The one piece wrapping LE sheeting. I made the mould sheeting quite a while ago, but had no confidence that this will go well.
It turned out that I was correct. While the mould did a reasonably good job, there was no way to adhere the sheet LE to the wing ribs and spruce LE to create a satisfactory gap free bond. As I was approaching the "grab the hammer" stage of building anger, I decided to pull the sheet LE off the wing. No amount of coffee will be enough today...
In a hindsight, the only way I could get it done satisfactory was to make "negative wood piece" to the ribs LE (all the way to where the sheeting go) to hold it in place while the glue dry.

I may upset few people here by saying that while I was originally excited about scratch building a Jerry Bates design, the more I progress into this build I am more and more disappointed. It seems that he went to great length to complicate things. From the foam core vertical fin, the complex bends landing gear, the ailerons servo connections and associated ailerons hinging system and obviously the wing LE design. I will add here the context that I am not claiming to be a scratch-build expert in any way, but suffice to say that I have built my fair share of scratch build R/C aeroplanes over few decades and a quick search on this forum should find few of them. Therefore, I think that I can say that considering the very high quality of the plans, Jerry has gone the extra mile to complicate the construction unnecessarily.







Cheers,
Eran
Old 09-08-2020, 07:03 PM
  #56  
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What about ripping the leading edge sheet you formed, down the middle, and glue it on one half at a time? Then you could use tape and clamps to hold it tight easier than trying to make it fit using the formed wood alone
Old 09-08-2020, 07:21 PM
  #57  
erans
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Hydro Junkie - We think the same. Since I took the photo above I took the sheet out of the bin and cleaned most of the glue off it (while it was still wet) with the thought of cutting it as you suggested.
I will see how this goes on another day when I am not as pissed off ; )
It takes nothing from the fact that the proposed construction method is not the best I have seen by a long shot...

Cheers,
Eran.
Old 09-08-2020, 08:10 PM
  #58  
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The only reason I suggested it is that I do similar things when I build my boats. Then again, my boats aren't exactly the slowest things around either
Old 09-14-2020, 12:52 AM
  #59  
erans
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After salvaging the moulded 48" piece from the bin, I decided to stage the glue process.
I first glued the spruce LE to the balsa to fix it into place.
I then made from scrap melamine board a "negative" to the shape of the rib + 2.5mm balsa sheeting. Using this "tool" (and forcing the rib + sheeting into it while the glue dry), I glued each individual rib (first all the "tops" and then repeated for all the "bottoms"). This took quite a few hours...

I then attempted to mould the another 48" x 2.5mm balsa sheet, but it split in half. I had no other choice but to use a 36" x 2.5mm sheet as there are no more 48" sheets in my two local R/C shops.
Using the same technique, I glued it into place and then made a small sheeting piece for the gap.








Cheers,
Eran
Old 09-14-2020, 09:50 AM
  #60  
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Looks good!
I was afraid that you had already thrown everything in the trash ...
Old 09-14-2020, 03:18 PM
  #61  
erans
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Nece - Thank you. I was not far from taking a hammer to it... Years ago I made the decision to place the hammer in the far side of my Cave so it won't be in arms reach on days like the one I was attempting to glue the LE...

Cheers,
Eran
Old 09-15-2020, 12:43 AM
  #62  
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With the LE sheeting out of the way, I can now get on with the final touches for the wing construction.

I took advantage of the easy access to the front mounting wing-bolts plate (located inside the wing, mid ribs height) and made a cardboard tube (out of toilet paper roll) to serve as a guide for the wing-bolt. This is another deviation from the plans which calls for a "foam insert" between the sheeting and the plate.
Next, I added the 7/8" x 3/32" balsa pieces to the back of the TE at the ailerons section (the curved TE).








Cheers,
Eran
Old 09-16-2020, 03:49 AM
  #63  
erans
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Bottom of the wing TE sheeting.






Cheers,
Eran
Old 09-17-2020, 01:13 AM
  #64  
erans
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Continuing with work on the wing, I am getting close to permanently fixing the ailerons in place. My current plan is to glue the ailerons to the rod, which will rotate freely in the wing acting as the hinge.

To stop the ailerons from moving sideways in the bay, I glued additional pieces of balsa to the "side wall" so the fit has almost no gaps (only the width of covering material).
Next. I glued a birch-plywood "bushing" to the inboard balsa rib (the outboard rib is already birch-plywood).
I glued a piece of plywood to the balsa rib W1 where the rods ends touch, and made a similar arrangement in the wing-tip. This locks the rod in place preventing any side movement.
I then did some cosmetic work to the fitting of the wing-tip and the wing TE (where the plywood ribs I made had a blunt end).













Cheers,
Eran
Old 09-19-2020, 02:21 AM
  #65  
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Eran, as you know I'm also building the Giant Astro Hog right now. I already have 10 posts here and can now add images and URLs/links.
I uploaded my pictures from the construction to GoogleDrive. Here is the link if you are interested.

To make the construction a little easier for me, I made some changes and drew plans for them. I also uploaded these. Maybe these are also interesting for you.

Best regards,
Manfred
Old 09-19-2020, 03:14 AM
  #66  
erans
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Manfred - Thank you, it is awesome. I was about to request the drawings for the fin and rudder from you following your comment in the previous post. I downloaded them and this will save me from having to CAD them myself. Looking at your drawings, it seems that your CAD skills are better then my own. Same I can say on the build photos, your workmanship is very impressive (if I may say so).
Using the pin hinges for the ailerons was one of the options I was looking into. However, I got too intrigued to test the carbon rod solution. I hope I won't regret it later... I also liked the fact that you went with dowels instead of the forward wing screws.

Cheers,
Eran
Old 09-19-2020, 08:45 PM
  #67  
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Eran - Thank you.
I think the carbon rod solution is a very good way to control the aileron. Sometimes when I see your work here I wish I had done it too. I'm sure you won't regret doing it this way later. Everything is planked with 3/32" balsa, there is enough material to sand something if it gets stuck somewhere.

One thing, if you also build the rudder according to my drawing, you have to be careful. I made the rudder a little wider than in the plan. The rudder area seemed a bit small to me.

Bye,
Manfred

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