Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Rossi .81 ducted fan

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Old 06-16-2008, 05:51 PM
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justinh
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Default Rossi .81 ducted fan

I just picked up an old rossi .81 ducted fan engine. I was wondering if any of you guys have had any experience with one of these. I'm wanting to run a prop on it and stick it on a nitro models bobcat.

The thing doesn't have a drive washer at all, i'm not sure how i will get a prop on it. Any suggestions for glow plug, fuel, prop? Also it has 61 on the case but 81 on the mounting lug, I think its a .81 is that correct? its rear intake, rear exhaust and the housing is removeable too so I think i can run it backwards.

Anyways, just looking for advice, suggestions as I don't have any experience with a motor like this.
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Old 06-16-2008, 08:44 PM
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Default RE: Rossi .81 ducted fan

I picked up one of these NIB at a swap meet so I'm interested in any suggestions too. I plan to stuff it into an old F1 plane that has yet to be completed.

Prop size is the main question for me (of course also on where to get the weird size stuff). Lets say 200mph target speed.
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Old 06-17-2008, 12:12 PM
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Default RE: Rossi .81 ducted fan


ORIGINAL: justinh

I just picked up an old rossi .81 ducted fan engine. I was wondering if any of you guys have had any experience with one of these. I'm wanting to run a prop on it and stick it on a nitro models bobcat.

The thing doesn't have a drive washer at all, i'm not sure how i will get a prop on it. Any suggestions for glow plug, fuel, prop? Also it has 61 on the case but 81 on the mounting lug, I think its a .81 is that correct? its rear intake, rear exhaust and the housing is removeable too so I think i can run it backwards.

Anyways, just looking for advice, suggestions as I don't have any experience with a motor like this.
I have this engine also, drive washer and stud + nut all come with this engine, if you dont have a drive washer some pieces are missing. The .81 rossi was a bored out .61 and the correct displacement was stamped into the mounting lug. I was thinking a 10x10 prop spinning at close to 20k would work. I was also looking for a smaller .61 head as the large head of the .81 probably weighs a lot and would not be needed on a fast plane with the head in the wind
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Old 06-22-2008, 07:18 PM
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Default RE: Rossi .81 ducted fan

Hey jsutinh:

I had a Rossi 81 on an F16 Ducted Fan. Great engine...........turned 22000 rpm on the ground with a Byron Fan unit.


Frank
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Old 06-22-2008, 07:36 PM
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Default RE: Rossi .81 ducted fan

what did you run for a glow plug and fuel?

I tried to get the thing going today on 30% with a apc 10x10. i couldn't get it to stay running, having fuel problems. I think I may put a pump on it.
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Old 06-22-2008, 10:01 PM
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Default RE: Rossi .81 ducted fan

A very good glow plug is the K&B HP #7300 for that type of engine if you are running 25% or more nitro.
You are trying to pull too much prop. That Rossi makes about 4.5 HP but it does that around 23,000 rpm.
If you could get the 10X10 to 19,000, that would take almost 5 HP, your engine at that point would be lucky to be making 3 hp... way short.
I would stay away from the smaller apc 9" props for your application because of the small hub. Perhaps cut down and or change pitch on the 10"ers.
Whatever prop you go with keep the following thought in mind and not a prop blade[:@]


APC Suggested RPM Limits
Glow Engine (sport props)

Maximum RPM=190,000/prop diameter (inches)
(For example, a 10x6 glow engine prop should be limited to 19,000 RPM)

If you are pushing the limits, inspect both blades on both sides in the 1 inch zone near the hub before every flight, look for white marks. If found, discard the prop.
At run up, keep anything you care about out of the prop arc.

You may want to think about carbon props and good luck with that...source, lead time, the right dia./pitch and cost. This is what led me to scrap my K&B 100df prop plane plans.
A good wood prop blank re-shaped may be the answer.
I hope you have more luck than I did.
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Old 09-12-2008, 01:34 PM
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Default RE: Rossi .81 ducted fan

make sure you use pipe pressure to feed the engine, you can get the prop driver washer from axe rossi any time, check your motor for head shims if there are none keep to 10 percent nitro or get some shims from axe rossi. for props look for zz props or bolly props as they make carbon props in the size you will need
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Old 09-12-2008, 02:13 PM
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Default RE: Rossi .81 ducted fan

Hi!
If it's an original Rossi .81 engine 20-30% nitro is way way to much .
These engines had heads made for low nitro fuel (5-10%). Drive washer could be had from Rossi in USA...or Europe.
I would try a 10x10 APC prop. Axle diameter is 8mm.
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Old 09-12-2008, 08:14 PM
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Default RE: Rossi .81 ducted fan

YUKONFLYR, do you have the large (Byron) head??? Do you want to part with it??? If so, send me a PM!!! I've been looking for the Byron head for quite some time now... Thanks

DF
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Old 10-31-2008, 12:25 AM
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Default RE: Rossi .81 ducted fan

Hi all,

Can anyone identify this engine? I can't see any writing on it and don't like to take it out. It is about 90 size.
Thanks
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Old 10-31-2008, 07:10 AM
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Default RE: Rossi .81 ducted fan

It looks like a K&B but the flats on the sides stumps me, it may be a earlier version.
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Old 10-31-2008, 07:15 AM
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Default RE: Rossi .81 ducted fan

ORIGINAL: shawn45

Hi all,

Can anyone identify this engine? I can't see any writing on it and don't like to take it out. It is about 90 size.
Thanks
My first kick at the cat is that it is a KBV .82 fan unit you got there. The carb sure looks K&B!

http://www.mecoa.com/kb/aero/ductedfan.htm

But those flats.. hmm.

MJD
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Old 10-31-2008, 07:30 AM
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Default RE: Rossi .81 ducted fan

The carb direct mounts to the block like a BVM. The K&B s that are current use an adaptor.. I'm confused. KBV?, why not. KBV did make a 91 too. The edge of the engine mount may have the size stamped on it.
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Old 10-31-2008, 01:16 PM
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Default RE: Rossi .81 ducted fan

BVM .81

Cylinder head mostly round with flats on the sides. Carb angled and bolted to the rear of the block. The .91 & .96 have fins that extend to the rear giving it an oval shape. Clamp on exhaust header is a BVM for sure.

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Old 11-01-2008, 12:10 AM
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Default RE: Rossi .81 ducted fan

Ok, took it out, but funny thing is, there is no marking anywhere!!!! Maybe it was a secret CIA drone flying over soviet... LOL
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Old 11-01-2008, 09:02 AM
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Default RE: Rossi .81 ducted fan

IMHO it's BVM
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Old 11-01-2008, 11:44 AM
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Default RE: Rossi .81 ducted fan

Definitely a BVM (KBVM )...but just exactly what size? My guess is .81 as well.
The backplate/carb and the drive spool is virtually identical to my .91's...The .91/.96 were made by Nelson and look VERY different. (.96's had purple heads and drive spools )

There was/is a K&B .82 but I think the same basic engine was used to make the KBVM .81...correct?
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Old 11-01-2008, 07:18 PM
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Default RE: Rossi .81 ducted fan

Looking at the picturs in this link, very close to 82. some slight dif. http://www.mecoa.com/kb/aero/ductedfan.htm

Thanks
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