RE: Is there a small 61?

RE: Is there a small 61?
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RE: Is there a small 61? - 4/27/2005 6:25:59 AM

Harry Lagman

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From: Auckland, NEW ZEALAND
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quote:

ORIGINAL: DarZeelon
That particular engine, like most other engines "highly acclaimed" by their manufacturers, actually do nothing in the real world; not what they are claimed to be capable of.

I was only saying this number is impressive for a non-Schneurle, 'run of the mill' engine designed over 30 years ago.

I hope you can agree with this statement...

These figures prove nothing either, but I'll share them anyway...

I have not seen a K&B .61 of any kind do 13,800 with an MA 11x7. I have seen a recently broken in K&B .61 C Lee modified 6535 wih an APC 12x6 on it peaking at 11,300. This thing made more noise than my Jett .90L! I would have eaten my hat if this engine had jumped 2,500 rpm with an 11x7 but we didn't try that so my hat is safe for now.

Right next door a minute or two later, I saw an elderly, high mileage ASP .61 do 11,700 rpm with the same APC 12x6 prop.

About 10 minutes later, another guy spooled up (sorry Dar

) his OS .61 FX (my wager for the mystery engine) with an MA 11x7 and got 13,400. All were at sea level.

The ASP and the OS both left a positive impression that day. The K&B reminded me how far we've come in the last 30 years.

Edited - typos

< Message edited by Harry Lagman -- 4/27/2005 6:28:22 AM >

(in reply to DarZeelon)

Post #: 76

RE: Is there a small 61? - 4/27/2005 7:08:31 AM

William Robison

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From: Mary Esther, Florida, FL, USA
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Harry:

Go back and recheck FBD's post #58. It w not an 11x7 that turned 13,800 rpm, but an 11x6.

quote:

11-6 MAS 13,800
11-7 MAS 12,900
11-7.5 MAS 12,200
12-6 APC 11,400
11-8 Graupner 10, 600
13-8 APC 9,200

His number are very cflose to mine.

Bill.

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Post #: 77

RE: Is there a small 61? - 4/27/2005 7:10:29 AM

William Robison

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Harry:

I should specify that those numbers are with the "Standard" bore carb - with the 0.375" Perry "Pump" carb they are higher.

Bill.

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Post #: 78

RE: Is there a small 61? - 4/27/2005 7:11:46 AM

DarZeelon

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From: Rosh-Ha'Ayin, ISRAEL
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quote:

ORIGINAL: Harry Lagman

About 10 minutes later, another guy accelerated (edited by Dar ) his OS .61 FX (my wager for the mystery engine) with an MA 11x7 and got 13,400. All were at sea level.

Larry,

I wanted to see how long it will take for someone to guess this (quoted from the MAN 05/03 engine shootout - Dave Gierke)...

The MA offers light loads, in its up to 11" props.
Using the Prop-Power calculator, punching in the same HP number from the APC@13,000 and changing the prop load constant to the smaller MA number, produced 13,398 projected RPM...

Very close, I would say.

If Jim says his CF K&B does this 13,800, I tend to believe him, especially if it is a PDP, since my MVVS .49 can spin a Bolly Clubman 11.5x6 (very similar load) at 13,600 with the tuned silencer.

And BTW, sea level and higher altitude RPM numbers differ very little, since prop loads are reduced by the thinner air, like the power is.
Power output differs by very much, however, despite RPM remaining unchanged.

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(in reply to Harry Lagman)

Post #: 79

RE: Is there a small 61? - 4/27/2005 7:16:35 AM

Harry Lagman

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From: Auckland, NEW ZEALAND
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quote:

ORIGINAL: w8ye

I have a K&B 6550 CF Lee engine and it does the 11-7 APC at 13,800. It's incredibly loud. Uses the old K&B square carb that resembles a HB carb except all silver.

I have a Direct Connection Kaos that I've set up for the K&B. The plane did nave a Fitzpatrick but I sold that engine to Hobbsy.

Enjoy,

Jim

Bill, this is the figure I was referring to. I don't discredit this figure - I simply haven't seen anything this high myself. FBD's and yours are consistent with what I saw with the 6535 - a pumper with the Perry pump carb.

< Message edited by Harry Lagman -- 4/27/2005 7:20:00 AM >

(in reply to w8ye)

Post #: 80

RE: Is there a small 61? - 4/27/2005 7:22:10 AM

w8ye

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I guess I'm comming in late here? Somewhere back up the way on a previous page I must have mentioned about my K&B 61's?

I had four at one time. This was the fastest of them and yes it is PDP as were two of the others. It has the new style muffler on the left that Fly Boy Dave is holding in this picture but the back end is machined off and it has a 1/2" ID aluminum tube pressed into it by Clarence Lee. It's the loudest engine I've run in recent years. More so than a fox 35 with no muffler.

I ran several other 61's with the same prop and this one was outstandingly fast compared with all my other 61's. I sold all my K&B's but this one.

The slowest of the K&B 61 PDP's did the APC 11-7 at 13200 and it had the Perry carb.The fast one has the old square carb somewhat like a HB carb.

i ran Some other engines that day with the same prop. MDS 58 11,600, MDS 68 12,700, Kraft/RJL 61 12,500, Super Tiger G61 ringed 13,000.
Enjoy,

Jim

< Message edited by w8ye -- 4/27/2005 7:39:41 AM >

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Post #: 81

RE: Is there a small 61? - 4/27/2005 7:30:06 AM

Harry Lagman

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quote:

ORIGINAL: DarZeelon

The MA offers light loads, in its up to 11" props.
Using the Prop-Power calculator, punching in the same HP number from the APC@13,000 and changing the prop load constant to the smaller MA number, produced 13,398 projected RPM...

Very close, I would say.

Dar, see post #73 above. The MA 11x7 appears to load slightly more than the APC 11x7 at those revs. My own testing indicates a similar pattern. I don't think an engine doing 13,000 with an APC 11x7 will rev materially higher with an MA 11x7.

In my opinion the relationship between MA and APC props of the same size can only be expressed on a case by case basis; ie, there is no blanket formula.

(in reply to DarZeelon)

Post #: 82

RE: Is there a small 61? - 4/27/2005 7:40:40 AM

Harry Lagman

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quote:

ORIGINAL: w8ye

It has the new style muffler on the left that Fly Boy Dave is holding in this picture but the back end is machined off and it has a 1/2" ID aluminum tube pressed into it by Clarence Lee.

That's what the C Lee 6535 K&B I saw had - a large diameter shiny aluminium "stinger". It was hideously noisy!

(in reply to w8ye)

Post #: 83

RE: Is there a small 61? - 4/27/2005 7:52:29 AM

William Robison

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Harry:

Sorry, I missed Jim's post about the 11x7 at 13,800 rpm.

Yes, I know what the 6535 engine is, I have a couple and several of the 6560 versions as well. Just wasn't sure you were talking about the "Pumper" engines.

Bill.

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Post #: 84

RE: Is there a small 61? - 4/27/2005 8:09:54 AM

Flyboy Dave

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From: San Bernardino County, CA, USA
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I wonder why the Lee modified muffler was so loud....there's no baffle in
there to begin with. Did he run the stinger all the way up to the fattest part
of the pipe. That was an old experimental thing from the early 70's....with
tuned pipe experiments.

(on m/c expansion chambers)

He had something up his sleeve, because generally speaking....enlarging the
diameter of the pipe stinger will not effect an increase in rpm. It will however
give a very large boost in torque....at the sacrifice of RPM.

FBD.

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Post #: 85

RE: Is there a small 61? - 4/27/2005 8:23:56 AM

w8ye

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Looking up inside the stinger, it goes no further than just enough to affix the stinger in the so called muffler.

Enjoy,

Jim

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Post #: 86

RE: Is there a small 61? - 4/27/2005 11:14:09 AM

FenceMagnet

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"In my opinion the relationship between MA and APC props of the same size can only be expressed on a case by case basis; ie, there is no blanket formula."

it depends strongly on where in the torque/power curves the engine is operating with that prop..... if you are already past the power peak, switching from the APC to a MAS will have less an effect than if you were half way up the upslope of the curve....

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Post #: 87

RE: Is there a small 61? - 4/27/2005 12:10:41 PM

Harry Lagman

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quote:

ORIGINAL: FenceMagnet

it depends strongly on where in the torque/power curves the engine is operating with that prop..... if you are already past the power peak, switching from the APC to a MAS will have less an effect than if you were half way up the upslope of the curve....

If the two props load similarly, how can this be so?

(in reply to FenceMagnet)

Post #: 88

RE: Is there a small 61? - 4/27/2005 1:18:18 PM

DarZeelon

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From: Rosh-Ha'Ayin, ISRAEL
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Larry,

My own experience with MA and APC props, in 9-11" diameters, is that the APC will always load the engine more than the MA.

The 10x6 size APC overloaded a tuned silencer equipped MVVS Q-500 engine to 12,700, getting it off-the-pipe, when a same size MA was spun at 16,100, obviously on-the-pipe.

The 11x6 size on a muffler equipped engine resulted in 600 RPM less for the APC.

It is probably a prop-by-prop case with MA, when all the APCs are the same.

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Post #: 89

RE: Is there a small 61? - 4/27/2005 2:05:44 PM

FenceMagnet

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From: Treasure Island, FL, USA
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"If the two props load similarly, how can this be so? "

that's the point..... they don't !!!

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