forster .99

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forster .99

Postby propwobble » Sat Nov 26, 2005 9:13 am

I have a two speed .99 with no serial numbers on the front of the cylinder.
The bypass cover says "Forster Bros". The cylinder clearly has cast bullseye ejector pin impressions. Does that make this an original Forster replacement cylinder casting or was there a period when Forster stopped numbering cylinder castings on .99's ?

Have been wondering about this for years.
many thanks
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Forster 99

Postby max hansen » Sat Nov 26, 2005 12:02 pm

The 99's I either had or saw over the years also had the bulls-eye pin marks on the intake manifold only smaller . Had a 1955 one with a serial #but it only had a 1/4" plug . I had a M&G made in Denver that was missing the serial # but had the old pin marks & a 1/4" plug. Also like you say it may be a replacement cylinder . Any help ? MAX H. :lol:
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Postby propwobble » Sun Nov 27, 2005 9:08 am

Hi Max

It was a good try.
My engine has the 3/8 plug. It has the smaller ejector bullseye marks on the bottom of the intake manifold as well as larger ones under the exhaust on the cylinder casting. (definitely cast in)

Since Randy picked up the Forster line, I was kinda hoping he had he difinitive answer. In the Forster parts section he states:

"The M&G version made in the late 1970's had a slightly shorter crankshaft and front housing. These engines may appear original but here's the secret of how to tell them all apart:

Look at the ejector pin marks under the exhaust on the cylinder. These appear as 2 round marks about 3/16 in diameter. The marks are made from 2 pins in the mold that push the part out of the cavity after it's cast.

Original Forster production had a bullseye pattern on the pin.

M&G versions had a smooth, cast finish. "

I don't have another engine to measure against for crankshaft length.
Mine is a smooth casting but I can't recall a Forster with a rough casting, if that is what he means. I'm leaning toward replacement cylinder because you say 1955 had serial numbers and I have the 3/8 plug. Still would like to know for sure.

Cam
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99

Postby max hansen » Sun Nov 27, 2005 11:20 am

Cam ,I think what Randy means is that the pin marks under the exhaust & on the cylinder were smooth & no bullseye . My info states that the M & G engines were identical to the last 99's Forster built in 1946 & the M & G's were built using original parts or the original dies. I would be willing to bet that yours with all the bulls eye die marks & 3/8" spark plug is a factory Forster with a replacement cyl.as the M & G's & RJL's had a 1/4" spark plug . MAX H. :lol:
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Postby MECOA » Sun Nov 27, 2005 4:16 pm

Okay here's the facts...

M&G's had smooth ejector pin marks on both the venturi and cylinder casting.

M&G screwed up on the crankshafts and made them short. Instead of scraping them the crankcase was shortened.

The molds we both used are the same original ones made back in 1936

M&G modified the molds to fit newer style die casting machines.

I fixed all the ejector pins to have the "bullseye" pattern on them however the person I had operating the die casting machine closed the mold and the slide on the pins and broke them off. If you look at the later cylinder castings we made you will see some damage deep between the fins just above the pins. We decided to leave the pins short and mill off the pin mark. Short pins will leave a aluminum column sticking out of the casting so they must be machined off.

All 99's we made were stamped RJL0001 etc
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Postby propwobble » Sun Nov 27, 2005 7:16 pm

Max,

Yes, the description of the smooth ejector pin marks is clear read it in context first time around as if I had the plain marks I would have presumed an M&G engine and never written this whle thing. Brain fart as I read it out of context the second time around. Just like me trying to make a simple thing complicated.

Based on the history just posted by "site admin" and plug size, I am inclined to figure that our estimating this one as a replacement cylinder is correct.

Randy, thanks for the history and info. I am still wondering if Forster might have built some of the .99's in the mid fifties without serial numbers. Anderson refers to the engine having been " resurrected for rc" at that time.


Cam
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99

Postby max hansen » Sun Nov 27, 2005 8:01 pm

To make things worse there are guys like me who rebuilt two 99's a while back for a collector & drilled & tapped the cylinder for a 3/8" plug . Bad Boy ! MAX H. :lol:
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Postby propwobble » Mon Nov 28, 2005 9:15 am

I am resonably confident the one I have is not a Maxster Special but now I will always be skeptical of every forster I see, serial number or not. Personally, I can understand doing it for a flyer wanting to use a certain type of plug but are you sure you want to admit to it for a collector. I know some real historian types who will hunt you down if they ever find out. Did you sign your work?
Now, about that hush money!
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99

Postby max hansen » Mon Nov 28, 2005 4:54 pm

I do that sort of things locked in my shop , late at night & wearing a mask ! They were RJL engines & he wanted to use the big plugs of which he had plenty. MAX H. :lol:
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Postby propwobble » Mon Nov 28, 2005 7:23 pm

Now we've got your number Max 8) [/code]
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Postby casting » Thu Mar 29, 2012 12:06 am

I am resonably confident the one I have is not a Maxster Special but now I will always be skeptical of every forster I see, serial number or not. Personally。I agree with your opinion,thank you!If anyone is there a better idea, saying that out and share,thanks!




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Forster 99 Torque curve values for Real Flight Simulator

Postby asssssss » Mon Feb 04, 2013 9:01 pm

To make the Forster 99 an accurately simulated engine in Real Flight (ver 6.5), the following values are needed. Can someone please provide them?

Thanks


Full Throttle fuel consumption (oz/minute)

Idle percentage of torque curve (%) When at idle, how far the torque curve is shifted to the left.

Idle torque (% of maximum)

Weight (oz)

Torque curve (oz-in) at the following RPMs:

1500
2000
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
9000
10000
11000
12000
asssssss
 

Postby chiefss » Tue Feb 05, 2013 12:17 am

Well when you consider a Forster 99 was never an R/C engine I highly doubt to are going to find any info on idle output. They were designed to run at wide open throttle.

Also as they were gasoline ignition engines they ran forever on a couple ounces of fuel.

Mine is Serial # 1950. My dad bought it in 1938
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Postby chiefss » Tue Feb 05, 2013 2:41 pm

Also, if you run one over 7000 rpm you won't have to worry about any power output because you probably just ruined it.
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Postby asssssss » Tue Feb 05, 2013 6:51 pm

chiefss,

Real Flight is a simulator, so they simply provide a wide range of RPMs to accommodate a variety of engines. Many of the torque entries for a given motor are zero where those speeds don't apply.
Good point about lack of a throttle. Looks like no torque info is available then, as the only way to get various readings is using different sized props to apply different loads. Given the rarity of these engines, it would be unfair to ask an owner to load down their Forster and possibly damage it.

Thanks
asssssss
 

Postby chiefss » Wed Feb 06, 2013 12:28 am

They aren't really all that rare, they were made through the middle 50's. Now the first models are rare.
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