Marty d's CH-701 build log

[Kyle Communications]

Nice job...you know of course that is the main strength in the design.its actually supplied completed like that from ICP for the Savannah kits because it is the core of the main structure

 

 

[Marty_d]

Nice job...you know of course that is the main strength in the design.its actually supplied completed like that from ICP for the Savannah kits because it is the core of the main structure

Thanks... no stress then!! Yeah Zenith supply them completed too, also the wing mainspars. Anything solid riveted I think.

 

 

[bexrbetter]

There you go Bex. At least one of them matches the plans

i call luck,

 

 

[bexrbetter]

From the cheap inferior 701 copy thread (otherwise known as a Savannah) ..

 

Interesting, the CH701 doesn't have any SS rivets (to my knowledge!)

I seem to remember seeing different Marty a few weeks ago going through those plans I mentioned I got. I could be wrong but I swear there was a handful in a few strategic spots so be wary.

 

 

[Head in the clouds]

You'd have to be nuts or know nothing about metallurgy to use ss rivets (or any ss fasteners) with aluminium.

 

If you need a stronger pull rivet you'd use monel (cupro-nickel) preferably with an electrical insulation medium like Duralac but that's not absolutely essential unless it's to be immersed in seawater.

 

It's standard procedure in yacht fittings for 50+ years ... but put ss and aly together and the aly will start corroding immediately.

 

 

[Marty_d]

From the cheap inferior 701 copy thread (otherwise known as a Savannah) ..

 

I seem to remember seeing different Marty a few weeks ago going through those plans I mentioned I got. I could be wrong but I swear there was a handful in a few strategic spots so be wary.

I don't think there are. I've been poring over the plans for 7 years and I can't recall ever seeing any rivets other than Avdel Avex 1/8" and 5/32", and solid aluminium.

 

This article specifically mentions the corrosion problem with SS so it would seem unlikely that he'd include them.

 

Aircraft Construction, Riveted Joints (Part 2 of 2)

 

 

[bexrbetter]

No problem Marty, ears still ringing from an 18 hour trip sitting up the back of 2 x A330s, memory not to be trusted.

 

Go with the people who know when it comes to riveting, the US Military;

 

https://www.recreationalflying.com/tutorials/scratchbuilder/MIL-R-47196A.pdf

 

As per 3.5, my 20+ year old wing that I just stripped with the zinc chromate is like brand new, despite all of the rivets being stainless steel, I can certainly understand Heintz avoiding them from a retail perspective though, there's no way you could trust people to do the required prep.

 

 

[nomadpete]

I've just visited Marty's 701 manufacturing facility. He's very good at those solid rivets, too. If you guys need any solid riveting done, I'm sure Marty would ace it for you in no time flat.

 

I'm very impressed with your project Marty. It's coming along very nicely.

 

 

[Marty_d]

 

Thanks Peter, it was good to catch up.

 

 

[Marty_d]

Been a while but progress is slowly being made!

 

The front fuselage is now complete (ignoring little things like firewall, seats, cabin frame, instrument panel etc...)

 

Actually ran out of 1/8" rivets when nearly done, that's 5,500 of them used. Found a local supplier which was lucky.

 

 

 

 

 

 

 

 

 

 

[Narrabeenrick]

How many hrs have you logged on the build mate?

 

Cheers

 

 

[Marty_d]

How many hrs have you logged on the build mate?Cheers

Absolutely no idea. I probably should have recorded them but have never bothered. Started when my eldest son was 2 and he's 9 now.

 

 

[Head in the clouds]

Absolutely no idea. I probably should have recorded them but have never bothered. Started when my eldest son was 2 and he's 9 now.

That's 61,322 hours for the log so far, then.

 

It shows the big difference between scratch built and kit built!

 

 

[onetrack]

Marty, you'd only shock yourself if you kept an accurate log of the hours. All labours of love consume an inordinate amount of time, you simply just can't say you'll have a project finished in "X" amount of hours.

 

We have a local saying about mechanical repair/restoration/construct operations. "Double the number and go to the next highest unit".

 

That means, you look at a job and say to yourself, "Ahh, that's easy! That'll only take 10 mins!" It eventually takes 20 hours before you actually finish it.

 

You look at a more sizeable job and think, "We'll, I guess we can knock that off in a couple of weeks". The more sizeable job then ends up taking four months to complete.

 

You take on a project, stating, "I'll have this knocked over in six months!". The project ends up taking 12 years to finish. You get my drift?

 

 

[Marty_d]

Next bit requires me to get the cabin frame welded up. I've got all the chrome moly for it, so have made a 3D view of the frame plus a wooden jig (90x35 framing pine) to hold everything in place.

 

If anyone else is scratch building, I can't upload the SKB file here, but PM me and I'll email it to you. Feel free to use it, but please double-check all dimensions first.

 

SketchUp is available for personal use as a free download.

 

 

 

 

[bexrbetter]

I can't upload the SKB file here,

.skp file you mean.

 

.skb is an automatic backup file that needs to be renamed to .skp

 

 

[Marty_d]

Go the metal cut ready for welding - now I just have to find someone willing to weld it!

 

 

 

 

 

 

[Kyle Communications]

Hey marty those wing mount U sections you have made on the cabin frame. Are they made from Chrome Molly?...the Savannahs are made from stainless steel then welded to the chrome moly frame

 

 

[Head in the clouds]

Hey marty those wing mount U sections you have made on the cabin frame. Are they made from Chrome Molly?...the Savannahs are made from stainless steel then welded to the chrome moly frame

Umm? As I understand it stainless must never be welded to CRMO because the joint will be very brittle. I'm no metallurgy expert but that's what research indicates ...

[Kyle Communications]

all of the Sav's those mounts we have tested must be stainless because a magnet will not stick to it al all..it does to the frame but not the U tags

 

 

[Marty_d]

Definitely not SS Mark... plans call for 0.080" 4130 plate for the U brackets and that's what they are. Yes they need to be welded too - hope there's enough top and bottom to weld to, they only protrude about 2mm.

 

 

[Kyle Communications]

Danny needs to make a new cabin frame for his S and mine has a lot of rust internally so we are making a jig to do just what you have done for both of ours

 

 

[Marty_d]

Yes a jig is the only way I could see to do it - position the frame in 3D CAD and draw in the wood to hold it in place.

 

 

[onetrack]

mine has a lot of rust internally

How do you get a lot of rust internally in your frame? Does it have a lot of openings which allow moisture and salt to enter?I would have thought a frame fully sealed against any moisture ingress would have been an important part of any airframe design, where metal that is prone to corrode is used.

[eightyknots]

How do you get a lot of rust internally in your frame? Does it have a lot of openings which allow moisture and salt to enter?I would have thought a frame fully sealed against any moisture ingress would have been an important part of any airframe design, where metal that is prone to corrode is used.

That is a good question.

How can such corrosion be prevented?