Updating old Schluters.....

Here’s one for Pete
Retro helicopters
Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Updating old Schluters.....

Post by Pchristy »

Originally it would have been fixed pitch. However, when Schluter brought out the "Gazelle" (same basic mechanics, but collective), he also brought out a collective upgrade kit for the Cobra and DS-22. This one had the upgrade fitted when I got it, which was handy because the mechanics set I substituted for the original was from a Gazelle!

I still had the original "flapping hinge" head until I donated it to another restorer a while back. It was in poor condition, but he has metal working capabilities and would be more able to restore it than me!

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Pete
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: Updating old Schluters.....

Post by bluejets »

ah...ok..

Like seeing your restoration/conversions, brings back when I built my own way back when.

Used a manual from John Drake I think it was.
Two full years work for a few hops but it was a real achievement in those days.
Had small amounts of success and it really tried out my machining and wood working ability.

Moved on to a used Morley Hughes 300 and then ended up building 2 from new for others around the ridges.

Went later on to the Hirobo Falcon and then the little Shuttle ZX which is still my favourite.
Could be set up wild or mild, really nice units.
Still have it here.
Others sadly went in the January 2013 flood we had here.
Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Updating old Schluters.....

Post by Pchristy »

Yes, the John Drake book was very good, if you could get past the maths using obsolescent measurement systems! (SLUGS?!?!) :)

My first heli was a Morley, from the days before he did kits. It came as a "plan-pack" and required a substantial amount of engineering work to complete! Luckily the place where I worked at the time had a very good mechanical workshops (I was on the electronics side), and the two guys who worked in there were extremely helpful! I think they enjoyed doing something a bit different from the usual boring stuff!

I learned to fly on that, and followed it up with a Lark, which my wife bought me for Christmas! I still have that Lark, though like the original woodman's axe, not much remains "original"! ;)

The Lark is not the easiest heli to fly, but back in the day, it was CHEAP! And the spares were VERY cheap! Also, if you could fly a Lark, you could fly just about any helicopter! All the others were so much easier!

I've had quite a few Hirobos down the years, and still have a soft spot for Shuttles. My newest heli is an electric Lama, with a 3-blade head that is heavily based on Shuttle mechanics.

BTW, if you need any spares for the Shuttle, my son is now the importer for Hirobo, and contrary to what RichMax have been saying, all spares are still readily available!

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Pete
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: Updating old Schluters.....

Post by bluejets »

I'll keep your suggestion about spares for the Shuttle in mind.

I have a spare tail rotor belt and have actually rebuilt the clutch once before.

Has a full metal swash plate so not much to wear out there.

I think there were 2 different versions for the tail drive belts and mine I believe is the shorter one.

Don't have any spare blades so tend to rely on good luck so far in that respect but the damper rubbers in the yoke blade holders must be getting past their use by date now, will need to check .

By the way, I found this brilliant site in the UK, you may know about it.
For details on many types and brand of choppers.
http://www.vrhc.co.uk/index.php/en/
Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Updating old Schluters.....

Post by Pchristy »

Yes VRHC is a very useful site for information on vintage helis! You'll find some contributions from me under the "Lark" section! :)

It was started by a guy in the UK, but has now been taken over by a very friendly and helpful guy from Austria (I think!).

Klaus has expanded the site quite a bit since he took over, and added a lot of European brands.

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Pete
Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Updating old Schluters.....

Post by Pchristy »

With the Lark project now completed, time to turn back to the DS-22. This has been on hold for a while, due to an awkward problem!

The tail-rotor drive on these machines is like a big speedometer drive cable (5mm), which also happens to be left-hand wound. I'm told they originally were manufactured for Amsterdam trams! Whatever, this means they are very difficult to replace! 5mm is a bit of overkill, and there are German suppliers offering 3mm replacements. However, these mean replacing the outer part of the cable as well as the inner, and since this winds its way up through the fuselage, is a last ditch option!

The new gearbox casings have an extra lug, which makes accessing the grub screws that hold the adapter to the gearbox output shaft difficult. Also the new, one-piece chassis further obstructs access to said grub-screws!

The easy solution is to attach the adapter to the gearbox prior to installation, and then tightening the grub screws on the wire drive after everything is in place.

This is great in theory! Unfortunately, my adapter hadn't been disturbed in over 30 years! The original metric grub screws had all been replace by BA ones (presumably someone stripped the threads!) and one of them that gripped the wire drive had had its head turned off!

I bought a set of left-handed drill bits, and finally managed to get the offending grub-screw out - without damaging the wire - only to find the wire drive thoroughly corroded into the adapter! Neither Plus Gas nor heat would shift it! In the end, I very carefully cut it in half with a Dremel cutting disc!
Imageadapter by Peter Christy, on Flickr

Again, by being very careful, I was able to finally get it off without damaging the wire drive! PHEW!

Once this was over, reassembly went very quickly, and the DS-22 is now awaiting first test hops!

ImageFinished by Peter Christy, on Flickr

The battery sits neatly in the space previously occupied by the fuel tank:

Imageinterior_1 by Peter Christy, on Flickr

I've run it up in the back garden, just enough to get it light on its skids, and all appears well so far!

Since this is such a major change in the mechanics, I'll be doing a lot of low-level hovering for a while, until I'm certain nothing is going to shake loose or break!

Both the DS-22 and the Lark have been fitted with FrSky Neuron ESCs, and the amount of telemetry this provides is staggering! On the Lark, the telemetry logs clearly indicate that I've got the motor type and gearing pretty much spot-on, and I'm hoping the DS-22 will be the same.

On an aeroplane, its quite easy to change the prop size to suit! On a heli, you are mostly stuck with the "prop" size and gearing, and have to "guesstimate" the motor and battery requirements. The run-up in the garden looked promising. First proper tests will either be tomorrow (Sunday) or Monday.

Watch this space! ;)

--
Pete
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: Updating old Schluters.....

Post by bluejets »

Have you thought about using the flex drive shaft from model speed boats..?

I used to buy the inner flex drive (LH)in either 3 or 4mm diameter for use with the hydro and it ran a K&B 45 front exhaust rear rotary valve induction with power pipe so quite a bit of oomph there and it worked fine.
The liner is a type of nylon tube which itself fits inside a thin wall brass tube such as K&S tubing. I think either 1/4" or 5/16" was used there.

Method I used was to make any flex adaptor from stainless steel ( due to in water use only) drill the end in the lathe just a tad oversize and with the use of a simple alignment tool, hold everything together and silver solder with blue tip cadmium rod.
Simply not possible to clamp the prop end with grub screw and the drive end I found better with the silver solder arrangement as the grub screw would tend to bend the flex ever so slightly , enough to throw it out of line and create all sorts of vibration problems at 20,000 rpm plus. :shock:

Never had a failure and it ran true every time.

If interested, I can show a drawing of the adaptor, maybe even a photo if it is still hanging on the wall of my workshop.
Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Updating old Schluters.....

Post by Pchristy »

Thanks for the pointer! I was unaware of model speedboats using something like this. My only reservation would be that the Schluter mechanics take the t/r drive from the second stage reduction, so turning in the opposite direction to the motor. This means the drive needs to be "wound" in the opposite direction to that used on a boat, which I guess would be direct drive.

Also, for something like the Cobra, you are looking at a length of around a yard - a bit less for the DS-22 and Gazelle, but still a few feet! Are they available in these sort of lengths?

My German contact tells me that it is possible to use a 3mm inner, and slide a thin walled outer down inside the existing outer tube. I'm in the process of ordering one for a possible future project. When it turns up, I'll post an update.

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Pete
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: Updating old Schluters.....

Post by bluejets »

Yes the cable is available in either CW or CCW but most I have seen are maximum of around 400mm long and most seems to be 4mm these days.

Liner is called high temperature teflon inner and it usually slides inside a brass thin wall tube.

I'm fairly certain that speedo drive cable is the opposite to standard glow engine rotation and most of those are 3mm. Would need to search a bit i think.

I'll see what is around.

Just remembered another source.......flex drive on grinders and such like dremel.

Motorcycle speedo drive cable..... https://www.ebay.com.au/itm/SPEEDO-CABL ... zGlQ6qsB

https://www.ebay.com.au/itm/Vintage-NO ... wdzVXm8vb


Teflon tubing .... https://www.ebay.com.au/itm/PTFE-Teflon ... 13ilu4H0Q
Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Updating old Schluters.....

Post by Pchristy »

Some good pointers there - though a long way from the UK! ;)

But at least I've now got some "search parameters"! Google always work best when you know precisely what to ask it for.....! :lol:

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Pete
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