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My Savannah S model rebuild Blog

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Hi Tom

 

It needs to be cleaning vinegar NOT normal vinegar its 1% different in some compound. I tried turps, metho, acetone, trichlorethelene,isoproply alcohol...amonia did work better than all the others at the time but the vinegar is by far the best. It still needs to be on there for a fair while then it comes off reasonably easy...quite easy with the gernie but the issue is its a 12ft x 4 ft sheet and both sides...so there is a lot of vinegar and time involved and handling the sheets too

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Reg Brost and I discussed pre-forming the fuse corner skins a while back. It seems the pre-load on the curved corners causes distortion in the flat side, top and bottom sheets. (Look at the bulges between the frames on S Savs). May not apply to your build as you are using thicker sides. Give Reg a ring he may be able to help on the pre-forming method.

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The corner skins the top and bottoms are all still 0.016 its only the flat vertical sides we are putting the 0.020 on. I will be putting 0.020 top and front D skins on my wings though. Was looking at preforming the D skin a bit to make it easier to bend around the nose ribs

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Reg Brost and I discussed pre-forming the fuse corner skins a while back.

 

It is a fun job, even with his purpose built press and formers. Even having been involved in forming the corners for a couple of builds I didn't use it for my own build even though it was available and local. I believe the "pillow" shaped panels are attractive and will help quieten the fuselage at takeoff. That is how they designed to be, stressed!

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I only want to start the bend where it goes around the nose. The sheet will probably only be about 150 deg bent. That "stress" will still be there but the sheet is thicker so I think it will need just a little extra help to go around the nose

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I doubt that the "pillow" look on the sides is a design feature but is an uninteded consequence of ICP needing to send a package of parts that take up the least volume. The same "pillow" look can be seen on the underside of the leading edge between the ribs. The blind rivets are only supposed to be in shear, not tension and sheer, it also applies side load to the fuselarge longeron angles causing them to become non-concentric, lowering their resistance to buckling.

Obviously the fuselage is more than adequate, but as a pure structure?

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So you would recommend that the curved fuselage sides would be better for absolute strength if the sheets that fom the curved corners actually be prebent some what to help remove the tension forces?

Using that analogy that means the wing sheeting D section would also benefit from a prebent form when being pulled over the ribs. The standard fit when I built my XL I was surprised how much tension there had to be on the skins and then of course tension on the rivets would be very high...not so much in sheer

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Well maybe ICP wasted their 300 grand that they spent on their design software then. I am always skeptical about some of the "refinements" that we do to make things look better, without running the mods through the design software. The exception was the rudder extension mod, which I would have done anyway, since it offered a lot of function as well as the look. Coincidently the factory version was nearly identical to the Aerokits scratch built version when the parts arrived. I wonder how that happened.

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Similarly, after John Gilpin (JG3 from this forum) started to remove slats and fit Savannah Classic planes with vortex generators, lo and behold, ICP produces the Savannah VG not so long thereafter. Nevertheless, I count this as a positive. Aircraft companies willing to incorporate continuous improvements -even borrowing good things from others- is just the company I wish to be associated with. ICP appears to be such a company.

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As I said the structure as supplied is more than adequate, that doesnt mean that it can't be improved, an aeroplane is a million compromises all flying in formation. The fin/rudder is not the only deficiency in the Savannah design, there is insufficient dihedral, the stability in roll is only a little better than neutral. Increasing the dihedral makes the aircraft far more pleasant to fly, as Mark has observed, the noseleg needs strengthening, particularly on the XL/S as the more upright castor angle (6deg) increases the landing and steering loads. The noseleg attachment on the firewall is prone to cracking (both top and bottom attachments).

Having said all that, from my 12 years of ownership I have found the Savannah to be a very practical and safe aircraft, and would build another without hesitation.

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All of the plans for metal aircraft I have seen require that the leading edge covering sheet be pre-formed before being attached, I'm sure that preforming the fuselage corner sheets will make for easier construction and a better looking result (provided that you dont kink the part).

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All of the plans for metal aircraft I have seen require that the leading edge covering sheet be pre-formed before being attached, I'm sure that preforming the fuselage corner sheets will make for easier construction and a better looking result (provided that you dont kink the part).

 

You haven't seen Zenith plans then. There's absolutely no pre-forming of the leading edge skin - it's clecoed to the bottom of the mainspar, pulled around the nose ribs with ratchet straps and clecoed to the top spar.

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The 701 and Savannah share the same designers, I should have said Nearly All Of The Metal Aircraft require a preformed LE.

Just look at the RVs and Monnett designs.

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The 701 and classic Sav have a much rounder leading edge for the slat vent, the leading edge sheet wrapped around that LE far easier than thr VG/XL/S wing section.

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Steve they just copied Reg's design when he sent it to them...I think Reg also had something to do with the adjustable seats as well

 

Reg reinforced the rear edge of the fin with two angle stringers too, but I was interested to see that they didn't deem them necessary to accommodate the added load on the fin from the extended rudder.

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Did some work on Mabel...well for Mabel this weekend. Finally got to get something done after the past 5 weeks or so of turmoil. Took all of the 20 thou sheets to Dannys place and we rolled them out one by one and marked out the top and front D wing skins which will be 0.020 and the bottom wing skin which is still 0.016. Both fuselage sides which are also now to be 0.020. Got most of Danny's skins marked on the 0.020 sheets and his side skins as well. This friday I have organised a guy I know who has a sheet metal workshop he just happens to have a 12ft guillo so Danny and I will go there and cut all the long lengths we need and we are ready to drill all the sheets. We have already done the top and bottom skins and the 4 curved skins at my work as the guill there is 3100 so we could do them and they are 0.016 so then there is going to be lots of drilling. Marked up another 0.020 sheet that has a few whoopsies in it as a Dskin so now we have complete drill jigs for all the skins on a S so others can benefit from it if they need to replace a skin. They just need to buy the raw sheet and we have the drilling jigs.

 

Danny got this rivet remover tool from Spruce for a drill that makes the drill stay in the centre of the rivet and doesn't elongate the hole. I bummed it yesterday so I could open up my wings. Damn I am impressed with it so have ordered one for myself and spare drills as I broke one already. The spar is critical so do not want to oval any holes if they are ok. Doing the first wing looks so far that the spar maybe ok. There maybe some damage at the very end of the main section out near the tip on the bottom side only but I think I can easily fix that and make it even stronger so at least 1 spar looks good so that will save a lot of work. Only 2 front ribs look damaged and we have some spares here so thats cool.

 

Will know more when I get further along this week with de-skinning the wing. I think there must be about 500 grams of farm dirt in the wing ...you can see in the pictures. This aircraft spent the first 240 hrs of its life up in Blackwater then the last 100 hrs on a farm out in western NSW doing mustering and fun flying. Just shows dirt can get anywhere. The whole aircraft will need a good clean up the front as well there is a lot of red dirt stains on the inside as well. Everything will be stripped out and cleaned before too much longer anyway. I have the seat bottoms out now ready to fit the twin sticks also I am changing the seat well bottoms to be more comfortable as well. Peter Bleys has done it to his Savannah and made different seats. I sat in it a few weeks ago when we flew up there and its really comfortable. His seat wells are lower than mine as he has the later version that has the smaller in height as mine is but I am pretty sure I can redo the well to make it very comfortable. I have attached a couple of pics of Peter's seat well and the seats he has made up

 

 

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Good stuff.

Hey, Mark, can we get a pic of the de-riveting tool you mention there?

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RIVET REMOVAL TOOL from Aircraft Spruce

 

This is the tool...works an absolute treat. I borrowed Danny's to do the spar but was so impressed how simple it is and how well it worked I had to get one and would use it on every rivet I have to do. It will be here next week :) but until then Dannys is getting some use

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RIVET REMOVAL TOOL from Aircraft Spruce

 

This is the tool...works an absolute treat. I borrowed Danny's to do the spar but was so impressed how simple it is and how well it worked I had to get one and would use it on every rivet I have to do. It will be here next week :) but until then Dannys is getting some use

 

Looks good.

And I've certainly had those moments when drilling the rivet goes wrong: notably when the sheet metal underneath is some sort of tab, and so inclined to bend down at an angle when the drill pressure comes on it...

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IMG_4752.thumb.jpg.40b74d4b7fc8548f9f75980bc4586370.jpgUsed that rivet tool a lot more tonight to get the top skin off....it is fantastic...should have got one ages ago. Well more dirt as you can see in the photos. The bottom of the spar is bent right at the outer so it will be fixable. The rest of the spar looks all fine. 2 front and back ribs need replacing and the outer half of the trailing edge spar. I can make the trailing edge spar at work so no drama. The skin tensions pretty much will be replaced so will make those...they dont take long at all and I have plenty of the section already bent when I made the longerons as I made plenty when I did them.

 

Tomorrow I will get the wing outside to turn it over and get all the dirt out and then will get the bottom skin off and the underside of the front skin. I can then get the ribs off the spar and inspect the spar properly

 

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[ATTACH=full]50644[/ATTACH]Used that rivet tool a lot more tonight to get the top skin off....it is fantastic...should have got one ages ago.

 

...

 

 

It is a bit cheaper to get the same product from Amazon: Amazon.com: Air Capital Rivet Removal Tool, Model# 65007 [Misc.]: Home Improvement

 

I ordered one today.

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$48.85 from Spruce about 11 bucks dearer on Amazon. I am lucky we have a friend who is also a RAAA pilot who flys weekly to the USA for work so he is bringing it back for me later this week. Just make sure you order spare drills as they are special. They screw in but I think I will make a mandril to take a normal HSS drill bit and just silver solder them into the mandril coupling.

 

Amazon can be really good for getting bits and pieces the killer is like Spruce is the freight charge. What you see on the website from here in OZ is not what the freight will be at checkout. I cant wait until Amazon starts here in a month or so as the freight should change a lot. I bought my Haimer 3D tool setter from Amazon and even with the $50US freight charge I still landed it here for over 100 bucks cheaper than I could get it from anywhere else in the world...even the main company in Singapore.

 

I will take some better pics tonight of the unit and how it works. It takes a little to get used to a few tricks and stuff also how it can block up but it does such a good job it is worth the bucks

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Wow Mark, it amazing how much dirt gets into apparently sealed compartments.

 

I suppose the question is: how do you prevent this from happening again?

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