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Old Apr 28, 2012, 10:26 PM
Bypass Ratio = Infinity
scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
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Roy- Give in buddy. You can't have enough contra planes. I haven't even finished my first one and I am already plotting my second, which of course is going to be bigger and a tad more powerful than the little spitfire. I pretty much have my heart set on doing a 100" Miss Ashley; I just need to figure out the power system. I do believe the Double 5330 would fly a 35lb. plane just fine for my taste at 6-7kW, but if I can splice two of those Turnigy's together with some 20-22" props with a ton of pitch it would be even better. I would love to have a plane with a 10kW+ power system.

edf nut- The build quality on the AXi is absolutely impeccable. Even if I do not use it on the Miss Ashley I will keep it for a future project. It is a work of art. Thatís interesting you have had trouble with the Scorpion's. I have read about trouble with the Hyperion branded Scorpions. Personally I have been abusing some 4035's in ChangeSun's 120mm 12 blade fan and they have been holding up great on 12s at 4.4kW sustained. We will see in the long run though.

aerophilia- I got your motor back together tonight. I reglued the magnets in the rear bell with JB Weld and wicked thin CA in between the magnets on the front bell. Its funny how there was no attempt to rough up the bell or magnets, they were super slick. The pictures are after scuffing everything up with 100 grit. FYI to anyone reading, masking tape makes great tack-cloth for getting metal particles off of strong magnets. Anyways, I will give everything 24 hours to cure and give it another go on Monday. Here are a few pictures of the magnets and bell right before reassembly. Sorry no pics during, it got hectic and I forgot.
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Old Apr 29, 2012, 05:25 AM
building building building!
aerophilia's Avatar
Melbourne Australia
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Looks great scatsob. I wonder how many of these motors that are made actually survive for very long without any modifications? Looking forward to Monday I guess I had better start thinking about getting the plane! Might be time to offload a few things at home that aren't getting much attention at the moment.

I think we need a "Contra Support Group" ! I have been you might say obsessed by the Bugatti 100 since I got into modelling a few years ago. I have a kit and a motor for it that I'll get around to finishing one day
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Old Apr 29, 2012, 06:11 AM
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United States, NC, Jacksonville
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Yeah, I have been doing the same thing. I am even selling some EDF stuff to fund this. Just the small stuff though. I have decided to not support 90mm, just 120mm and a Habu 2 when the airframes come available for everyday fun.

That Bugatti is going to have some interesting challenges. It looks like if you wan't it to balance the batteries are going to have to be located in the stabs.
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Old Apr 29, 2012, 07:03 AM
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Melbourne Australia
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Yep, battery placement is just one of the challenges! I figured one either side of the centre line, fitted vertically would work. Easy to access, no wing off etc for access. And then cram as much stuff behind that as possible!!
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Old Apr 29, 2012, 09:15 AM
Tow Dog.
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Just some words in a photo............................
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Old Apr 29, 2012, 10:37 AM
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United States, NC, Jacksonville
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Ok, I have been wasting some time doing research on which big Turnigy motor would be best for a contra conversion. I have narrowed it down to two. The RotoMax 50cc and the CA80-80. Both have similar kv but the CA80-80 can handle more power. I really like the CA80-80 except for one thing, the shaft is only 8mm. I would not normally be concerned with this, as I have put 4-5kW through 8mm shafts, but this shaft will be pretty long and have a 22" three blade prop with a huge spinner. On the plus side, an 8mm shaft would be easy to work with. The RotoMax has a 10mm shaft, which would be better for strength but a little more difficult to work with. I also don't know of any 10mm collets available. Thoughts?

Pilatuspc12...thats what I am shooting for.
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Old Apr 29, 2012, 12:58 PM
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I found some pictures of the CA80-80 taken apart and it looks like the ticket. One of the best parts is the bell extension used for mounting the propeller is removable. So for the front motor all I need to do is send that to my machinist to get the through-shaft bearing set. The rear bell will need a thrust bearing between the bell and stators and it appears there is plenty of room for that. The front bell could be held on similarly to the little CR50 I am putting in the Spitfire, with another thrust washer and collar. I just posted a WTB in the power systems classifieds to get one to play around with.
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Old Apr 29, 2012, 09:14 PM
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now were talking
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Old Apr 30, 2012, 07:27 AM
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Got an interesting email from AXi today. I asked them if they could make a longer shaft for the 5330 and see if they could do a double 5345. No joy on either.

"Dear Scott,



I'm very sorry to but we can not produce longer shaft becasuse we purchase it already in this lenght just like once per two years as volume is very small. We do not produce shafts directly.



About 5345HD double. Even double AXI 5330 is on the edge so 5345 can not be made as double motor at all. This consdruction would be too weak and problem.



Thank you for your underestanding.



Best regards Jan Vaclavik"

Guess I am on my own.
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Old Apr 30, 2012, 11:39 AM
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Found some more good pictures on the CA80-80. Looks easy to get apart and will be easy to put two back to back. As soon as I can get my grubby hands on a couple I will get started.

Sorry for all the off topic stuff. TBM is killing me with these retracts. I swear every other plane has the retracts in stock except the 72" Spitfire.
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Old Apr 30, 2012, 05:31 PM
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Basingstoke Roy's Avatar
United Kingdom, England, Basingstoke
Joined Oct 2005
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Hi Scott

That looks like the mother of all out runners & just begging to be turned in to a contra, you've got to go for it

It looks like you can remove the prop adapter from the front of the bell, which should make boring out a bearing seat easy, or even make your own bearing carrying prop adapter to bolt on.

The only trouble I've had with boring the anodised aluminium, is cutting through the hard skin, the tools tend to grab & leave a rough finish. It also take the edge of the tool in no time.

Watching with interest
Roy
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Old Apr 30, 2012, 06:36 PM
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Oh I plan to Roy. I am selling off things to do this. My fleet will not be large but it sure will be unique. I need to find the time to fly more too because I would love to go fly at something like SEFF or Joe Nall.

That is exactly what I was thinking on the prop adaptor. I just need to get the motor in hand to see if there is enough room in the one that comes with the motor to both house the bearings and still allow a prop to be bolted to it. If not then I will have a new one made.

I wonít have a problem with machining as I have someone much more competent than myself for that. I have a friend that was a machinist back in NASA's heyday when everything was handmade, he is really good.

Scott
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Old Apr 30, 2012, 07:02 PM
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Melbourne Australia
Joined Jun 2006
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Yeah, I just looked on the TBM site yesterday, and the P-51 retracts are readily available. Seems strange that the Spitty sets have been out of stock for so long.

That Hobbyking setup is going to be a monster. You realise you're gonna have to charge 4 packs just for one flight right? That's about the only downside I can think of having such a cool motor in a cool plane
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Old Apr 30, 2012, 07:03 PM
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You got to love the Baron also
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Old Apr 30, 2012, 07:16 PM
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Melbourne Australia
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Is it monday there yet? (just kidding).
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