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Author Topic: TD vs. Medallion fuel usage  (Read 1972 times)

Offline tom brightbill

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TD vs. Medallion fuel usage
« on: January 04, 2014, 05:06:41 PM »
Can someone give me a ballpark of fuel usage difference (if any) between the .049 TD and .049 Medallion assuming a direct swap in the same airframe?
Thanks, Tom
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Offline RknRusty

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Re: TD vs. Medallion fuel usage
« Reply #1 on: January 04, 2014, 06:41:29 PM »
If it's an original Medallion with a #2 single bypass cylinder, and you use the same prop as the Tee Dee, it should go longer on the same amount of fuel, though with less power and RPMs. There is another Medallion version that had a throttle ring and came with a #3 dual bypass cylinder(to compensate for the power loss caused by the throttle). But even without the throttle installed it still would use less fuel than the Tee Dee, which has the most aggressive bypass porting of any of the .049s.

As far as how much difference, I could only guess. A Tee Dee with a #4 cylinder running full scream probably uses 1/4oz a minute, but I never actually time my flights. I would think the Medallion would be noticeably less.

Rusty
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Offline tom brightbill

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Re: TD vs. Medallion fuel usage
« Reply #2 on: January 04, 2014, 11:36:14 PM »
Thanks Rusty,  My TD is one I bought in 1964. I have it in a 1/2 A sized version of a Shark 45.  I taken to calling it a Half a Shark.  I had a 1 oz. tank in it, but was only getting about 3 1/2 minutes, so I changed to balloon (not bladder) tank, but haven't actually tried it yet. In the meantime I bought a Medallion just in case. It appears to be of the pre-r/c vintage, based on the look of the cylinder, so maybe the #2 type? Thanks for the input.
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Offline RknRusty

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Re: TD vs. Medallion fuel usage
« Reply #3 on: January 05, 2014, 02:08:04 AM »
Tom, some of my 1/2A planes have become Half a plane too.
If you're curious about it, the "2" could be stamped on the lower barrel of the cylinder, or on one of the four small facings at the corners of the exhaust ports. Or possibly not stamped at all. The Tee Dee .049 usually has a #4 stamp.

Rusty
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Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
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Offline tom brightbill

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Re: TD vs. Medallion fuel usage
« Reply #4 on: January 05, 2014, 01:04:38 PM »
Rusty, They are just as you've described. The TD says 4 and the Medallion 2.  Thanks again. Tom
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Offline Jim Thomerson

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Re: TD vs. Medallion fuel usage
« Reply #5 on: January 05, 2014, 05:06:08 PM »
Back in the day, there were a fair number of contests with 1/2A stunt.  I flew TD's on pressure with 1.5 oz fuel.  Never owned a Medallion 049.
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Offline Andrew Tinsley

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Re: TD vs. Medallion fuel usage
« Reply #6 on: January 06, 2014, 02:45:29 AM »
Hello Tom,
I think Jim has hit the nail on the head. I have tried to run TD 0.049s in small stunt planes. I have tried without pressure and the results have been disappointing. A lot of people say they run without pressure. Well my experience is that they are difficult to needle running that way. I have put on a 40 tpi(?) NVA assembly from Texas Timers and then it is a lot easier to set the needle! But if you get this far, you may as well fly them on pressure as they go better that way! I am lazy and I don't like the extra hassle of pressure feed. I have taken to using a Medallion and this runs well without pressure and would be my preferred option. Pity I don't have more Medallions.
  Totally off topic, I much prefer running the Norvel BigMig 0.49 or 0.61 for stunt. More useable power and they are a delight to use. Even the AP Wasp is a better bet if you can sort out a stunt venture. The Wasps are not a patch on the TD or Norvel for quality, but as long as you don't try to get the absolute most power, they are a very good stunt engine. Watch for lose crank bearings from new, if the crank is a good fit then you are OK, the P/Ls are excellent, the rest is the usual Chinese quality!

Regards,

Andrew.
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Offline George

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Re: TD vs. Medallion fuel usage
« Reply #7 on: May 08, 2014, 08:14:40 AM »
Quote from: Andrew Tinsley on January 06, 2014, 02:45:29 AM
Hello Tom,
I think Jim has hit the nail on the head. I have tried to run TD 0.049s in small stunt planes. I have tried without pressure and the results have been disappointing. A lot of people say they run without pressure. Well my experience is that they are difficult to needle running that way. I have put on a 40 tpi(?) NVA assembly from Texas Timers and then it is a lot easier to set the needle! But if you get this far, you may as well fly them on pressure as they go better that way! I am lazy and I don't like the extra hassle of pressure feed. I have taken to using a Medallion and this runs well without pressure and would be my preferred option. Pity I don't have more Medallions.
Regards,

Andrew.


Sorry for the late reply but I somehow missed this thread. Some years ago a guy modified the intake of a TD to provide better suction. Although it was originally for RC it will work for CL also. Basically he drilled the intake just enough to insert aluminum tubing as an intake restrictor and re-drilled the sprinkler holes. Worked well for him.

George
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Offline Tim Wescott

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Re: TD vs. Medallion fuel usage
« Reply #8 on: May 08, 2014, 10:24:51 AM »
Quote from: Andrew Tinsley on January 06, 2014, 02:45:29 AM
I have put on a 40 tpi(?) NVA assembly from Texas Timers

More like 128 TPI.  I think the originals are 56 or 64.
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Offline Andrew Tinsley

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Re: TD vs. Medallion fuel usage
« Reply #9 on: May 08, 2014, 10:36:20 AM »
Thanks Tim!
I knew the Texas Timer NVAs were about double the number of threads to most of the originals (though some were 128 from Cox). The real snag was remembering what the tpi were for the normal Cox reedy!
 I have just been checking on some old notes. I see the difference between the TD and early Medallion was that the Medallion used about 30% less fuel than the TD.

Regards,

Andrew.
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Offline Tim Wescott

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Re: TD vs. Medallion fuel usage
« Reply #10 on: May 08, 2014, 11:09:21 AM »
AFAIK, the TD has a much larger venturi opening than the Medallion, so it can draw more fuel.  This makes it pretty touchy without pressure.

But unlike Tom, I never had the $$ for anything more than a Babe-Bee when I was a kid, so I have no direct experience.
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