Marty d's CH-701 build log

[Marty_d]

I hope you will share why you have departed from the standard CH701 and chosen to go with:

1. Savannah main gear?

 

2. Savannah nose wheel?

 

3. Savannah slats?

 

4. Savannah fuel system?

 

5. Savannah control mixer?

 

6. Savannah flap handle? *

 

7. Savannah Y-stick?

 

8. Savannah rudder pedals? 

 

9. CH750-style trailing edge?

 

10. CH750-style inset trim tab?

 

I am really intrigued!!

 

* I will be fitting a Mark-Kyle manufactured flap handle to my Savannah. This has a better (and safer) operating angle of the flap lever as well as an additional notch.

Mainly, because I'm a lazy cheap-ar*se.

 

The opportunity came up (in this site) to buy a Savannah undercarriage from a totalled aircraft.  Luckily another Tasmanian was buying the motor from the same aircraft, so he was able to bring back my bits too.  Unknown to me, the seller threw in the pedals (with brake cylinders), control mixer, Y-stick, flap handle, and doors with the undercarriage.  Pleasant surprise!  (Unfortunately, doors don't fit - slightly too big.  Will use what I can from them.)

 

The slats were laziness - it looked like a particularly difficult bit to scratch-build and I met a bloke in Bendigo with a set to sell.  They came back to Tassie bolted to my roof racks.

 

The tanks - 701 tanks are welded from 0.025" aluminium.  I don't know anyone who can weld that thin, and if I did, it'd probably cost a fortune.  Getting them from the US would be over $1k.  A bloke in Canberra was advertising a kit with long range tanks, I asked him if he'd sell the extra tanks separately, and luckily he agreed.  They're identical in size & shape to the 701 ones.  I prefer the Sav setup with the 7 litre header tank, so I'll be buying one of them too.

 

The 701 elevator trailing edge is like the wing TE - upper and lower surfaces meet at TE and are solid riveted.  The trim tab is a flat plate hinged at the TE.  I thought it was messy, especially when you look at the nice neat folded TE on the rudder.  So I looked at the 750 TE and copied it, along with the inset trim tab.

 

So there you go!

 

 

[eightyknots]

It all makes perfect sense.

 

Well done on picking up cheap parts.

 

 

[Marty_d]

Had a chance to do a bit on the plane this weekend, so got stuck into mounting the rudder pedals and bolted the horizontal tail on for the first time.

 

 

 

 

 

 

[Marty_d]

Further work on the "south end"... mounted the rudder, fabricated and clecoed the fixed fin.  Won't rivet that until the elevator cables are run but will fully prep it.

 

 

 

 

 

 

 

 

[eightyknots]

Great work Marty. With this kind if progress, you could be airborne at the end of summer.

 

 

[Marty_d]

Great work Marty. With this kind if progress, you could be airborne at the end of summer.

That's a nice thought but there's a lot more to do...  it'll be finished by the end of one summer, just not this one.

 

 

[IBob]

Hi Marty, presumably you are having to set a few countersink rivets. If so, what are you using to cut the countersinks? Thanks.

 

 

[Marty_d]

Hi Marty, presumably you are having to set a few countersink rivets. If so, what are you using to cut the countersinks? Thanks.

Hi Bob,

 

Nope, there's no countersink rivets that are actually countersunk.  Oh, apart from the elevator bellcrank I think, and that might even be solid rivets.

 

The whole plane actually uses Avdel Avex countersink rivets, but the riveter head is ground out so that it bends the countersink part back over to form a domed rivet when you pull them.  Apparently this gives the rivet extra force.

 

 

[IBob]

Ah, right. Yes, I recall the bit about reforming the rivets, hadn't realised there were no countersink holes.

 

There are a few on the Sav, mostly holding nut plates and the likes from rotating, but a few a bit more structural than that.

 

And one of the hard lessons I have learnt on the build is that you cannot put a neat countersink into sheet metal by simply using a larger bit (except perhaps by clamping the work and using a rigid drill press, or clamping on an external hole as a guide.... but most of the work does not allow that.)

 

Which is to say that, while I tried to find countersink tools at the correct angle for A3 and A4 rivets, at a reasonable price, I should have persevered....

 

 

[Head in the clouds]

IBob - in thin sheet metal you don't cut the countersink, you use a dimpling tool to form dimple recesses in both (or all) sheets. If you cut the countersink or oversize the holes you will massively weaken the joint. When you press dimples into the sheet metal you need to start with undersize holes so that when the metal stretches to form the dimple, the holes end up the right size (start with about 2.8-3mm for 1/8 rivets).

 

If you only have a few holes to do you can make a dimpling tool using a pair of dies (male and female) turned up in a lathe and drawn together with a 2.5mm SHCS and nut. If you have a lot of them to do then you make a similar pair of dies and draw them together with a hardened and headed mandrel in a standard riveter - naturally you don't break the mandrel each time, so that you can use it time and again, and it's hardened so that it doesn't get chewed up by the jaws of your riveter and so that it then releases easily when you take the pressure off the riveter handles. Note - don't pull the mandrel any harder than needed to form the dimple (which isn't very hard at all) with the riveter or, if the mandrel is properly hard, you will flatten the teeth of your riveter's jaws.

 

Alternatively, and perhaps more easily for most folks, you can use a rivnut tool and screw the mandrel into a nut (instead of a rivnut) on the other side of the dies for each hole you want to dimple, takes a few seconds longer per hole but it's no big deal in the scheme of things. 

 

 

[IBob]

Thanks for that, HITC.

 

It has been a small, and fortunately not a critical part of the build, but I have been less than happy with my hit and miss results.

 

 

[M61A1]

Countersinks can be purchased at reasonable prices at any aviation tool shop.

 

Countersink Tools, Pilot Cutter Integral 2 Flute - Product List - Henchman Products Pty Ltd

 

WWW.HENCHMAN.COM.AU

 

- Countersink Tools, Pilot Cutter Integral 2 Flute

 

Countersink Tools, Micro Stop Countersinks - Product List - Henchman Products Pty Ltd

 

WWW.HENCHMAN.COM.AU

 

- Countersink Tools, Micro Stop Countersinks

 

They are 100°, same as the rivets, most drills are 118°. If you have a really good eye you might be able to adjust the angle on a drill with a bench grinder, but you would also need a steady hand to get a neat cut, as countersinks are piloted.

 

If you want a really cheap way to dimple just a few rivets....find a bit of steel with the necessary size flat surface, drill the correct oversize hole for the rivet in use, then countersink that hole. use that tool as a bucking bar/dolly with a countersunk rivet, it will dimple the holes nicely in thin sheet, leave the rivet in place then set it with a proper bucking bar/dolly.

 

Works great for a handful but gets a bit tiresome if you have a lot to do.

 

 

[Old Koreelah]

Marty I haven't been following your log closely (my aircraft is wood and fabric, not sheet al.) so the following points may already have been raised by others.

 

Today I was replacing my fuel lines and learned a valuable lesson that I'd like to share with those like me, who didn't really understand why motor mechanics curse those oriental engineers and their tiny fingers.

 

I tried to design my aircraft to make everything easily accessible, but I didn't visualise doing maintenance.

 

As a result, what takes an hour to remove may take a day or more to replace. Fuel lines too close together, clamps too hard to get at, insufficient slack in flexible hoses, cables and wires to allow them to be easily removed and replaced. 

 

 

[Marty_d]

Thanks OK.  I'll bear that in mind during the build.  All good advice gratefully received!

 

 

[Marty_d]

Got some work on the doors done today.  I have a pair of Savannah doors but unfortunately they're the wrong size, so I'm drilling out the rivets and using the perforated channel on doors I'm making from scratch.  Photos below shows an original Sav door compared to my home built one.  

 

Subsequent photos show the door fitted to the fuse.

 

Question - the plan just calls for the single interior handle.  I reckon that's a bit risky.  Would I be better adding two more holding points (but then there's 3 spots on each door you need to open in order to get out - not great in an emergency) - or try to incorporate all of them with bell cranks and rods from the 1 handle?  Any experiences or advice?

 

 

 

 

 

 

 

 

 

[Kyle Communications]

Reg Brost made it up..I will look to see if I have any pics of mine....it works a treat

 

 

[Marty_d]

Reg Brost made it up..I will look to see if I have any pics of mine....it works a treat

Is this the one?

 

http://www.aerokits.net.au/prod02.htm

 

 

[Kyle Communications]

Yep thats the one

 

 

[Kyle Communications]

At the handle they are 2 ball links arrangements I am sure you can buy them easily...they are threaded and those rods have a thread on one end to screw into the ball links

 

 

[IBob]

Fallowdeer here has a VG Sav with the little over-centre latches on the leading edge of the door in addition to the main bottom latch.

 

They work fine (though he made himself a 3 point closer like Reg's for the pilot side.)

 

 

[Blueadventures]

Hi Marty

 

As you have the lower latch sorted; in my Nynja post #58 you will see the aft door latch I have made; very simple and hugely effective and has a spring to positive lock and you could do similar for the forward latch and connect these to the lower latch to allow opening.

 

Also for info Flylight in UK sell a door latch its spring loaded (image) and pull via s/s cable to pull for opening, these are very compact and positive locking.  I could see them or something similar that you fabricate working.  Other wise a s/s rod in 3/16 mm rod and some guides would work.  (Skyfox did this method)

 

I recon you could fab up similar to the UK ones.

 

Its got to be fun deciding on safe, fit for purpose latches.? (That's what I told myself at that same stage.)

 

Your build is looking great.  You should be at the cricket BBL tonight ?? ?  We have the WBBL in Mackay tomorrow night and Sunday arvo.

 

Cheers Mike

 

 

 

[Marty_d]

Hi Marty

As you have the lower latch sorted; in my Nynja post #58 you will see the aft door latch I have made; very simple and hugely effective and has a spring to positive lock and you could do similar for the forward latch and connect these to the lower latch to allow opening.

 

Also for info Flylight in UK sell a door latch its spring loaded (image) and pull via s/s cable to pull for opening, these are very compact and positive locking.  I could see them or something similar that you fabricate working.  Other wise a s/s rod in 3/16 mm rod and some guides would work.  (Skyfox did this method)

 

I recon you could fab up similar to the UK ones.

 

Its got to be fun deciding on safe, fit for purpose latches.? (That's what I told myself at that same stage.)

 

Your build is looking great.  You should be at the cricket BBL tonight ?? ?  We have the WBBL in Mackay tomorrow night and Sunday arvo.

 

Cheers Mike

 

[ATTACH]38281[/ATTACH]

Thanks Mike, I will go have a look at your Nynja post.

 

Those Flylight latches look good, might look into that. 

 

As for the cricket - not a sports fan sorry!  My brother-in-law will be there this evening though.

 

Thanks all for the advice!

 

 

[Blueadventures]

Hi Marty 

 

No worries; always keen to put ideas out there that may assist; I certainly get lots of info reading the posts.  I did not know of these type of sprung slide latches.  They are worth considering and the wire connector makes connections easy to do.

 

A search for spring loaded slide catches should source some to look at.  Also could bee made out of square or rectangular tube.

 

A friend up here is building a 750 and just finished off the wings; I've seen inside but on that visit the doors were off so did not see the latch mechanism he used.

 

Cheers Mike

 

Slide latch spring loaded.doc

 

Slide latch spring loaded.doc

[M61A1]

https://www.ebay.com.au/itm/Rotax-912/143104788840?hash=item2151b5c968:g:06EAAOSwEvZcTE2B

 

Your neck of the woods?

 

 

[Marty_d]

https://www.ebay.com.au/itm/Rotax-912/143104788840?hash=item2151b5c968:g:06EAAOSwEvZcTE2B

Your neck of the woods?

Other end of the state (unless there's a Scottsdale somewhere else in the country), saw this the other day.

 

I might contact and ask some questions.