OPS .67 ready to go for spring
03-01-2014, 03:23 PM
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OPS .67 ready to go for spring
This is/was the .65 part of the Screamin' Demon .65 that dopplered at 196-197 last season. It is now upgraded with the .67 marine 7-port piston/liner set, new bearings, and here for show and tell in the photo is an 11.5mm OPS venturi/NV assembly. I bought one with the idea that for all out top end the Jett .90 carb might still be holding it back. Then I actually measured the carb bore and found out it is all of 0.020" smaller than the venturi (0.435" versus 0.455" = 9.4% more area), so there might be a few rpm there but that carb works so sweetly.. not sure if I'll fly the now-SD67 without a carb. It does not have the forgiving manners you expect from these deltas. Wing loading is too high, tricky bugger to launch and to land safely. Nice to have a reprieve mid-tank.
The .67 liner is a thing of beauty with the external milling of the ports and all shiny like. Hope it was worth it, damn are those things expensive!
The .67 liner is a thing of beauty with the external milling of the ports and all shiny like. Hope it was worth it, damn are those things expensive!
03-01-2014, 03:51 PM
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I have an 8-day business trip to Dusseldorf in early May - where I am only needed about 3 days - and I plan to go see some people who make such things.. been looking forward to this for a while.
In the meantime the SD will have to do for now.
In the meantime the SD will have to do for now.
03-01-2014, 06:38 PM
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Get the 200 mph monkey off your back with the Screamin' Demon.
Anyone can spend a ton of cash on a state of the art ARF speed plane and do 200+, but I fail to see what that accomplishes at this point...?
It's your money, your time....I'm just rendering my 2 cents worth.
As far as what really counts [pure enjoyment], I'd build a slightly larger delta [or lengthen the one you've already got] and just have the time of my life running 0-5% nitro through that engine with a less aggressive prop.
Anyone can spend a ton of cash on a state of the art ARF speed plane and do 200+, but I fail to see what that accomplishes at this point...?
It's your money, your time....I'm just rendering my 2 cents worth.
As far as what really counts [pure enjoyment], I'd build a slightly larger delta [or lengthen the one you've already got] and just have the time of my life running 0-5% nitro through that engine with a less aggressive prop.
04-08-2014, 12:46 PM
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Hey MJD,
where did you get that prop driver and spinner setup for this engine.
I was contemplating to having a custom prop driver machined, to accept standard TRU-TURN spinners or something. But that will be a rather expensive piece of aluminium I bet...
where did you get that prop driver and spinner setup for this engine.
I was contemplating to having a custom prop driver machined, to accept standard TRU-TURN spinners or something. But that will be a rather expensive piece of aluminium I bet...
04-08-2014, 03:47 PM
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Actually what you see there is nothing special, but the prop makes it look so - it is a standard 2" Al spinner. The prop is a 8.2 x 11 D speed prop with deep cuffed blades. So together they make a fairly intimate package, but only good for fat 2" diameter nose rings like the Demon.
But.. I recently picked up a pair of official OPS .60/.65/.67 speed spinner assemblies. They look really nice, and they are much smaller (40mm IIRC). Same thing you see on the nose of the VAE .60.
But.. I recently picked up a pair of official OPS .60/.65/.67 speed spinner assemblies. They look really nice, and they are much smaller (40mm IIRC). Same thing you see on the nose of the VAE .60.
04-08-2014, 03:53 PM
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Oh wait, maybe I did not understand your question - these engines are ducted fan so they came with a standard backplate, washer and nut. These parts should be available from an OPS dealer. The really cool 10-13cc speed spinner assemblies (tapered collet backplate, spinner, spinner nut, prop nut) were $39 USD each. The type in this picture:
Last edited by MJD; 04-08-2014 at 03:56 PM.
04-08-2014, 04:26 PM
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Oh ok, so it's a standard drive collet from a DF engine...thanks.
I know a retired oldtimer who can whip out the most amazing pieces of lathe work...perhaps I can coax him into turning me some drive collets if I can't find the old DF engine parts.
Have you run the "67" yet? If so, how do you think it compares to the 60-65 engines? 100 bucks for a P+L set...I might break out the old visa if the power gain is substantial enough...
I know a retired oldtimer who can whip out the most amazing pieces of lathe work...perhaps I can coax him into turning me some drive collets if I can't find the old DF engine parts.
Have you run the "67" yet? If so, how do you think it compares to the 60-65 engines? 100 bucks for a P+L set...I might break out the old visa if the power gain is substantial enough...
04-08-2014, 06:10 PM
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No, the weather is still crappy and cold here. Usually, May 24 is about when it gets decent outside and the ground is solid enough no to sink to the core of the earth in your own backyard.
I've seen boat-lore that quotes a 10% gain in top end power though. I contacted Andy Brown about his marine .67 pipes, I might replace the MACS with something more, and I hate to use the word.., "radical"?. Ech.
Oh yeah I had to grind the blade cuffs to fit the 2" spinner. I'll have to check but I'll take a wild guess they fit a 40mm spinner.
I've seen boat-lore that quotes a 10% gain in top end power though. I contacted Andy Brown about his marine .67 pipes, I might replace the MACS with something more, and I hate to use the word.., "radical"?. Ech.
Oh yeah I had to grind the blade cuffs to fit the 2" spinner. I'll have to check but I'll take a wild guess they fit a 40mm spinner.
04-09-2014, 11:45 AM
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I feel sorry for you. I've flown right through the winter here. The weather wasn't always great, but if it's not raining or storming, I'm out there. The first Q500 race was flown last weekend actually.
Those pipes do look,nice...the one with the adjustable stinger is the ticket I bet.
The OPS "speed" spinner is 36,5mm in diameter. I think that prop would look right at home.
Those pipes do look,nice...the one with the adjustable stinger is the ticket I bet.
The OPS "speed" spinner is 36,5mm in diameter. I think that prop would look right at home.
04-09-2014, 01:54 PM
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The nice thing about getting snowed in during winter is not feeling guilty being buried in the workshop working on stuff for several days with warm weather outside.
