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K&B .48 vs OS 46 VXDF

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Old 08-27-2006, 07:26 AM
  #1
Boo2
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Default K&B .48 vs OS 46 VXDF

Hi,

The question is as title, which is the best 45 class ducted fan engine, the K&B .48 or the OS 46 VXDF ?

Thanks,

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Old 08-27-2006, 07:29 AM
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Default RE: K&B .48 vs OS 46 VXDF

The OS

Runs and tunes much better
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Old 08-27-2006, 07:36 AM
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Default RE: K&B .48 vs OS 46 VXDF

I'd agree OS are the better engines iv always liked them they are very reliable and have hardly no trouble starting at all.

Josh
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Old 08-27-2006, 07:41 AM
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Default RE: K&B .48 vs OS 46 VXDF

Josh,

Not to be rude but have you ever had an OS46 VXDF or a K&B 48?

You are more than entitled to your opinion but it would be helpful if you include your experience with the particular engines mentioned to make sure Boo2 gets informed assistance.

(apologies if you have had both of these engines but from your previous posts I am guessing not).
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Old 08-27-2006, 08:00 AM
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Default RE: K&B .48 vs OS 46 VXDF

Hi,

The old OS 46 was about the same as the K&B, but more reliable.

The new os46 (anodized head) is more powerfull, easier to adjust and very reliable!

It's the best DuctedFan engine i ever had. Easier to set than the OS 91

Go with the new OS 46, you wont regret it
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Old 08-27-2006, 08:02 AM
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Default RE: K&B .48 vs OS 46 VXDF

siclick33, Iv only had the OS but my Friend has the K&B i know what theyre both like and the OS is the best out of them.
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Old 08-27-2006, 09:03 AM
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Default RE: K&B .48 vs OS 46 VXDF

Larry Wolfe at Jethangar Hobbies liked the (then new) K&B 48 but soon after MECOA purchased the K&B assets they stopped making ducted fan engines dispite pleas from larry. The OS purple head 46VX is about the only curently produced 45 size DF engine that is universally liked, at least in the Turbax. If you have one of the few K&B 48's use it but don't brake any parts on it! If you're looking to purchase a new engine, I have one of the OS 46VX's and it works wonderfully.
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Old 08-27-2006, 06:42 PM
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Default RE: K&B .48 vs OS 46 VXDF

Thanks for all the replies, sounds like the OS is da man, esp if the K&B is not being made any more [sm=49_49.gif]

(those are reading glasses btw )

Boo
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Old 08-27-2006, 07:02 PM
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Default RE: K&B .48 vs OS 46 VXDF

PMFJI but I thought the only K&B engine that is about the same size as OS-46 DF engine is the K&B 7.5 ducted fan drum rotor engine.

I just checked a NIB one in my garage and that it what the box stated.

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Old 08-28-2006, 07:10 PM
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Default RE: K&B .48 vs OS 46 VXDF

According to the [link=http://www.mecoa.com/kb/aero/ductedfan.htm]K&B[/link] website there's two, but from what I've read (here and elsewhere) I don't think there's much chance of getting hold of the .48.

Can I pester you folks some more and ask which is the best fan to use with the OS 46VXDF ? The Thorjet one is easy to get here in the UK, but is the Turbax one any better does anyone think ?

Thanks,

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Old 08-28-2006, 10:24 PM
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Default RE: K&B .48 vs OS 46 VXDF

How about the OPS ? I have one used, serviced then stored away with pipe and thorjet 45 (not used) sitting in a cupboard! needs a new home! It was the most powerfull motor in its class when new......

Chris
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Old 08-29-2006, 12:54 PM
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Default RE: K&B .48 vs OS 46 VXDF

I think the first 'dedicated' K&B ducted fan engine was the 7.5 with rear exhaust and rear, drum rotor induction. Just before K&B closed business they redesigned it into the 48 version and only made a few. Larry Wolfe was flying a couple and liked it very much. A lot better than the earlier 7.5. At about the same time, OS redesigned "their" 46VR engine (which had the rear, disc induction and smallish carb) into the currently available 46VX-purple head with a huge carb and drum induction. According to Larry the OS purple head is THE 45 size DF engine to use. It's available, proven and performs. If you already have a different engine and want to use it, fine. But if you are looking to purchase a new one, this is it. The only fan I have experience with is the Turbax. I think most people in the US use this and most people in europe/UK use the Thorjet.
For what its worth, I have a Jethangar A4Skyhawk that weighs 10 1/2 pounds empty and it's powered with a Turbax and OS46VR, the earlier engine. With 10% nitro fuel and at our Utah field (4200 feet elevation) it flies fairly well. We'll call it 'scale-like'...not a missle, but OK.
Hope this helps.
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Old 08-29-2006, 03:20 PM
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Default RE: K&B .48 vs OS 46 VXDF

Nobody got the info correct.... The first K&B 7.5 ducted fan engines were rear exhaust and front intake design...They incorporated Perry Pumper carbs and a Perry pump mounted in the rear of the crankcase...Real pieces of garbage in my honest opinion....Second generation K&B 7.5's were rear exhaust/rear intake---Better design, more power, and a little more user friendly but no match for the OS engines---Especially the latest version of the little OS as it is one sweet engine. Excellent, reliable idle and will really scream!!! The last version of the K&B was the 48, but as previously stated was only a limited production run...

Kevin
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Old 08-30-2006, 08:56 AM
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Default RE: K&B .48 vs OS 46 VXDF

I have them all. My personal experience with the new OS VX (Thorjet - Weston mini-pipe) is it does not have the same power as the K&B 48 (Turbax - Weston mini-pipe). The OS does tune easier and will run to max RPM right out of the box. The K&B takes a long break-in and may need a bit of modding to keep the low end disk from turning but, in my experience, consistantly out performs the OS. Also, I haven't met anyone who has had long-term success with the new OS... hopefully, a few folk will post their experience here.

With that said, availablility is most likely what will make your choice for you.

Mark M.
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Old 08-30-2006, 10:06 AM
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Default RE: K&B .48 vs OS 46 VXDF

I have 200+ flights with the OS 46VXDF + Turbax I + MACS tuned pipe combination and the engine has performed flawlessly for every flight. In all of those flights, I had probably 3 dead stick landings and all of them were due to either running out of fuel or a failed throttle pushrod. The engine never once blew a plug. The only maintenance issues I have had have been periodic bearing changes.

The 46 VXDF is a very reliable, robust, powerful and user friendly engine. But the most important benefit of this engine is that it is in production and currently available.

The K&B 48 has been a "phantom engine" ever since it was "released", which was a single, very limited production run. Very few engines were ever made and it has not been available for several years, with no indication that that status will ever change in the future. JHH gave up pleading with MECOA to put the engine back into production several years ago.

Further discussion on this topic is pointless. If you want to fly .46 glow DF you really only have one (realistic) choice, and that is the OS 46 VXDF with either the Turbax or Thorjet fan units.

Regards,

Peter
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Old 08-30-2006, 10:16 AM
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Default RE: K&B .48 vs OS 46 VXDF

Yup, pointless! We've been around this bush before Peter. That is why I went and purchased the VX to see for myself. Availability IS the key.

Mark
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Old 08-30-2006, 10:45 AM
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Default RE: K&B .48 vs OS 46 VXDF

Quote:
ORIGINAL: MiragePilot

Further discussion on this topic is pointless. If you want to fly .46 glow DF you really only have one (realistic) choice, and that is the OS 46 VXDF with either the Turbax or Thorjet fan units.
But which of these fans do you think is the best ? (Or anyone else ftm)

Thanks,

Boo
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Old 08-30-2006, 10:56 AM
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Default RE: K&B .48 vs OS 46 VXDF

From what I could gather at the time, the OS needed more load to really shine. The Thorjet with the added blades gives you that load. The K&B 48 or 7.5 seems to shine using the Turbax. I'm sure the OS will work fine in the Turbax, just be careful not to over rev it or it won't last very long.

Do a search of the archives, you may find some more user stories. I remember a bunch of talk about the VX's losing power after a gallon or so. This is not to say they are useless at this point, just less powerful than new. Peter is the one person who seems to have had very good luck. Maybe he can measure the pipe length and let you know his break-in process, fuel, plug , etc..

Mark
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Old 08-30-2006, 11:13 AM
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Default RE: K&B .48 vs OS 46 VXDF

What kind of RPM would you see on the OS 46VXDF if you put a 8x8 prop on it?
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Old 08-30-2006, 11:21 AM
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Default RE: K&B .48 vs OS 46 VXDF

Search under the speed plane forum. I am getting approx. 22k on an orginal K&B (front carb) w/K&B black pipe and an 8x8 prop. I would think using a prop on a VX is a waste of money. You can buy a purpose built, for props, speed engine for the same money.
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Old 08-30-2006, 11:34 AM
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Default RE: K&B .48 vs OS 46 VXDF


Quote:
ORIGINAL: cobratraxxas69

What kind of RPM would you see on the OS 46VXDF if you put a 8x8 prop on it?
I do not know about 8X8 prop but I fly my Diamond dust with 9X6 APC prop and I tac it on the ground at 20K rpm on OS 46 and 22K rpm on K&B 7.5. You can add 2K more to the numbers when it unloads in the air.
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Old 08-30-2006, 12:50 PM
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Default RE: K&B .48 vs OS 46 VXDF

Hmmmm....maybe it's time for the K&B .48 on my Diamond Dust.....
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