Wren Engine Build...Missing something... maybe a manual?

[DDragon]

I posted this on the "other side"... I'll see if I get any answers here:


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Hi Folks,
OK... maybe someone that has built a Wren from a kit (Bell?) can help me out. I received my MW54 turbine kit and pre-built 2nd stage a few weeks back. Started the build as some of you know. I'm going over the manuals I received again. And it just occurred to me, I don't have any instructions on where to go after I have the turbine built.

What I mean is... no plumbing or electrical diagrams. Pictures or instructions. Not even something saying where to plug anything in. This occurred when I tried to figure our what the "Thermal Coupler/Temp probe" looked like. I couldn't find a picture of it, or how to install it ANYWHERE! I think I have it, a long thin piece of metal with a bigger cylinder on the end, which then has a green wire and JR plug connected to it. But no pictures...

So I have no idea how to connect it to the pre-drilled hole on the Interstage... or if it even goes there.

So to me, it seems like I'm missing something.

PLUS, I checked the WREN check list and the mounting bracket isn't checked off and is obviously missing from the parts I received. Is this not sent in the kit anymore?

Any help would be appreciated. I want to get this engine built and tested, but I don't want to make a fatal mistake.

Cheers,
Deron

[WayneBrown]

You can PM user 'Sara', she's the nice lady from Wren that scans this site for users who need help with Wren products.
There are a lot of 'end users' too, Chris Bergen, Ron Keith, Lou Paragallo, Greg Alderman, etc. that have these engines and may also offer help.

[Sara]

Hi Deron,

I've sent you a reply by ordinary mail, but I'll post it here for the benefit of anyone else who's interested. I can't post it on the other site, I don't post there any more because my posts might be seen as advertising. Never mind, as Wayne has just pointed out, I can talk to people on here!

There is no mounting bracket with a gas generator engine - that's for the thrust engine only. I can send one if you want one for running on a test stand.

For some reason, the section about fitting the thermocouple is missing from the current instructions ... I don't know why! You should have a small piece of metal and a p-clip in a bag with the ECU. The p-clip attaches to one of the screws on the FOD screen, the tab attaches to one of the exhaust screws and they hold the probe in place. I'm attaching a pic of the thermocouple on the thrust engine - the gasgen fits the same way but the end goes into the hole in the interstage.

What you have left over should be: gas canister, solenoids, gas supply fittings - all external to the engine but needed when you install the engine into the heli. There are instructions about fitting these with the Predator conversion kit.

Sara Parish
Wren Turbines

[DDragon]

Thanks Sara! I just received your email. That makes sense to me... funny I re-read and re-read the manual, and I thought something was missing :lol:

Thanks for your great service as usual! :thumbup:

I'll post this on the other group incase someone else has the same questions.

Cheers,
Deron

[Bell Bloke]

Sorry ddragon, I missed your posts, I've been away in Poland. Looks like I've got some catching up to do. Nearly missed the party. :lol:

[DDragon]

Hi Bell, Glad you made it!

Well, I finished the build and it looks great! Problem is when I was sitting back admiring my work I noticed a flat ring about 15.74 mm in diameter sitting on the floor in front of my workbench. I took a picture of it and asked Sara if it was anything I needed to worry about. Haven't heard back yet.

Do you recall anything like that?

Cheers,
Deron

[Bell Bloke]

OH BUGGER! Is it a shim about 15.5mm OD and 0.5mm thick?
Have you had your shaft tunnel appart and taken the spring out?

[Sara]

Well spotted, Bell Bloke! I've just mailed Deron, it IS the shim from the tunnel, we've given him instructions for getting it back into place.

Sara Parish
Wren Turbines

[DDragon]

Thanks Bell! Yes, not intentionally. The spacer "popped" out unexpectently when I was pushing the shaft in. Sara sent me instructions...:

After pulling out the turbine shaft, spacer and spring... it goes in before the spring and the spacer. I'll do that tonight!.

REALLY great to have both of you here! :thumbup: :YeaBaby:

Thank again Sara!

[Bell Bloke]

Don't forget to put the shaft tunnel 'tube' with the 'scribed' or 'marked' end in first or the end nearest the spring. So it goes Shim, spring, tube, with 'scribed or marked end first.'
Damn!! Dratt, and double dratt!! You've got to take it all appart now. Mind you you'll be able to do it in 280seconds blindfolded the next time around.
Actually all you have to do is:
This is from memory folks as I sit here without instructions so I may miss something out but here goes.
This is the fast way
1. Remove interstage where it joins the engine.

2. Remove fod guard but not the pipework.

3. Undo the 'LEFT HANDED' alloy compressor nut, WHILST! keeping your hand on the power turbine wheel thus preventing it from shooting across the room and onto your hard garage floor.

4. Remove power turbine wheel and shaft.

5. Remove the 'tube' from the shaft tunnel, and then the spring.

6. PUT IN THAT NAUGHTY 'SHIM'

7. Repeat the processes backwards from 5 through to 1. Job done!

8. Then place the larger of your testicles in a small simmering pan of homemade jam and say the words,
'Silly me I forgot the shim, I swear I'll never do that again.'
Then cross yourself twice, throw salt over your left shoulder and french kiss the cat.
If you do this I think everything should be ok.........well it works for me anyhow.

[DDragon]

That's what I was going to do.

BUT...I'm confused now... Sara said the end marked with the ring (I know which one it is) goes against the bearing so it would be pointing outwards ... but when you say to place this end in first. I'm thinking it will be in contact with the spring and not the bearing. From what I understand, this end (with the mark) is specially ground to be "true".

[DDragon]

It's ok Bell, got it now. Sara emailed me an clarified. The ringed end goes against the spring as everyone has been saying all along. I assumed this was the "special" end.

[Sara]

Sorry about the confusion, I've had a confusing day. I meant to say "against the spring" but for some reason (probably because I was trying to answer the phone, write invoices, pack parcels and make sure that the Wren guys leaving for Belgium this afternoon had got all their paperwork ) I got muddled.

Just going for a nice lie-down in a darkened room ....

Sara Parish
Wren Turbines

[rkeith2]

Sara taking a nap!

Sara never sleeps

[Bell Bloke]

Well I'm glad because it means I haven't been building my engines backwards for the past 3 years! :lol:

[DDragon]

Well I'm glad because it means I haven't been building my engines backwards for the past 3 years! :lol:

:rolling I was able to get it all sorted out in less than 10 minutes. If was an easy fix. Something that always "itched" at the back of my head though, "did I push the turbine shaft in all the way". I'm sure I did, but I still wonder. Everything seems to have seated correctly and the left hand nut is tighten as it should. And there is no lateral slop. So I must have done it!

Looks good now. I need to take a picture and show it off.

Makes one feel good to think "I did that". But all in all, it's a pretty easy process. I now need to figure out how to setup the plumbing on a test bed.

Bell, are there any documents that you know of that shows the plumbing. Wren sent an inline fuel filter and I believe (from my reading) that is goes after the fuel pump out and just before it goes into the turbine.

Also, what do I use to attach the 4mm fuel/air tube to the brass fuel/air lube tube going to the gear box. I have a 4mm to 3mm festo (not with the kit) I suppose I could use. But I couldn't see anything in the kit to do this and there are no instructions.

Cheers!

[Bell Bloke]

Sorry Matey, I'm a bit slow with my replies here! I've been editing my 'Wren Engine Bearing Change' cinematic masterpiece, just got to dub to sound and commentary.:lol:

Yes you are correct that the fuel filter goes after the fuel pump just befoere the engine, don't cut the pipe too short though, keep it neat but keep some slack.

Replied to your other post on that pipe from the gas generator to the gearbox, it's just pushed onto the brass pipe about 10mm to be safe. Remember when you run your engine to make sure oil/fuel is passing through this pipe! This is vital! If it is not after 1min, shut it down and talk to Wren or us here. However that said there is little reason as to why it should not work.
The main tubine shaft should spin freely and as you say there should be little or no end float. By spin freely, I mean that if you grab the shaft nut and spin it as fast as you can with your thumb and finger it will only spin for 2 seconds at the most. Bearings once run do sound a bit 'gritty' or 'shushy' this is normal. It's good practise to make a recording of your engine starts and engine cooling sequences in the early days, so that 50-60 hours down the line you can listen to the difference. This will help you to get the 'feel' for your engines health as the hours clock up.
I am certain that I could tell how many hours an engine over 5 hours old has done just from the sound of it in the cooling cycle...

[DDragon]

Thanks Bell, that's a good idea.

[Pinecone]

8. Then place the larger of your testicles in a small simmering pan of homemade jam and say the words,
'Silly me I forgot the shim, I swear I'll never do that again.'
Then cross yourself twice, throw salt over your left shoulder and french kiss the cat.
If you do this I think everything should be ok.........well it works for me anyhow.


:shock: :noteworthy :rolling :rolling