To Dee or not to Dee

pgang Wed Dec 14, 2022 6:45 pm

A few years ago this example of a TeeDee 051 came into my possession. I bought it with the intention of using it but since then have become hesitant, given the scarcity of new examples these days.

I would like to throw it open to the experts to try to work out the vintage of this model. Note that the price tag is likely in Aussie dollars.

I'm pretty sure the engine is new as I can see no screw head impressions on the mounts, and there is no staining on it at all. Note that the box says its from Santa Ana, so that's probably a clue.
Also of interest is what looks like oil residue around the propeller backplate. The cardboard is clearly oil(?) stained, so there is a bit of a mystery there. I can get a pic of the instruction sheet too if that helps.

So is it worth preserving (I'm not really the collector type), or should I be using it for what it was intended, ie - having fun? One reason for not preserving is that the packaging isn't in pristine condition. However, I do also have the cardboard sleeve it came in which has Cat No. 200 printed on it, so it's all complete.

GallopingGhostler Wed Dec 14, 2022 10:55 pm

Appears to be an earlier thin wall cylinder without wrenching flats on the uppermost cooling fin, something perhaps from latter 1960's? If it has the original instruction sheet, you may be able to find a dated copyright notice, which will help to place it within a couple years after.

Regarding disposition, that is up to you. Lately I have been seeing a lot of engines on E-Bay that appear to be from estate sales of departed baby boomers. Grandchildren and children don't seem to want them. So, they are sold as a lot at probably next to nothing, then the sellers profit from them, not the family.

Personally, I'd prefer to use such, as although they may be considered valuable, they are not ultra expensive valuables like with heirloom jewelry or collector motorcycles, cars, etc.

If you do decide to sell, there may be someone on this forum who lives within reasonable shipping distance, who would be willing to give you a decent offer, plus it gains appreciation from someone who values it.

But, that is my personal opinion, for what it is worth.

balogh Thu Dec 15, 2022 12:45 am

I would date it to after 1972 when the screen on the venturi was introduced..the white fixing wire covers the cylinder neck but there seems to be a groove there? In that case, it is a stepped wall cylinder. Whether without or with taper bore depends on if made after or before around 74? If thin wall cylinder as George suggests, it definitely would have taper bore, a feature that made early Tee Dees retaining their high performance for very long runtimes.

On the last photo the oil around the prop drive plate may be from the factory where the phenolic washer between the collet and drive plate may have been oiled. The same photo shows a shiny, unscratched piston that implies this engine has not seen any fuel through it.

As George said, check the Litho mark on the bottom left corner of the Instructions sheet, where a year was often - but not always - specified..

I would also use it, because if well taken care of and not abused, it may have hundreds of hours of runtime pleasure in the waiting for you.

davidll1984 Thu Dec 15, 2022 4:57 am

Someone correct me if I'm wrong but I believe almost every tee dee that has the thick wal cylinder som has no taper the older medallion has thin wal wit less power no extra boost port but has taper bore but it's possible to find thick ones that has taper cylinder like the older tee dee .051 and venom no. 7 cylinder twin boost i think the best to verify is to take it apart and push piston furter in its cylinder if it just drop free its not taper bore if it stay stuck at top its one

balogh Thu Dec 15, 2022 5:57 am

davidll1984 wrote:Someone correct me if I'm wrong but I believe almost every tee dee that has the thick wal cylinder som has no taper the older medallion has thin wal wit less power no extra boost port but has taper bore but it's possible to find thick ones that has taper cylinder like the older tee dee .051 and venom no. 7 cylinder twin boost i think the best to verify is to take it apart and push piston furter in its cylinder if it just drop free its not taper bore if it stay stuck at top its one

David, you may be right, thick wall Tee Dee stock cylinders had no taper. To the contrary, all old-stock thin wall Tee Dee cylinders have taper. In between thin wall and thick wall series, stepped wall Tee Dee cylinders made till 73...74 had taper, later stepped wall TD cylinders already had no taper bore.

I have a thick wall cylinder with taper, but that may have been made for another engine, like early Killer Bee, or Venom.

Out of curiosity I have checked my 3pcs of TeeDee 050 RC engines too. Each has thick wall, non-SPI cylinders, and a very mild, if any, taper in the cylinder bore (the piston does not fall through the cylinder, but is stuck 1/4 or half way up from the cylinder top)..these were all made in 1995 during the short, 2400 units production runs in the mid-90's

Anyway, this still does not change my recognition, that all, or most of my 049 and 051 TeeDee-s made before 1975 or so had taper bore

cstatman Thu Dec 15, 2022 2:59 pm

fly it as the maker intended

pgang Thu Dec 15, 2022 3:27 pm

Very interesting comments. The stepped wall was well spotted - I've just checked and there is a groove under the exhaust port.

The only other clue I could find is that the instructions (not dated unfortunately) describe Cox as a subsidiary of Leisure Industries. I presume that places the engine in the 1970's.

So we have a stepped wall, screen, plastic 'jewel' box, Santa Ana, and Leisure Industries as dating markers. Otherwise I will have to take it apart to check the bore, but I won't do that at this stage.

I think I probably will use it if the opportunity arises again. I was considering putting it in a Sig Hummer (which I've underpowered with a reed engine), but have come across a used Norvel in the past 24 hours so will use that instead. So the TeeDee remains in its box for now and lives to fight another day. I have a soft spot for this 1/2A stuff*, so I'm sure another opportunity will arise.

However, with GallopingGhostler I am also of the mind that these things will keep popping up for a while yet and besides, they're never going to be valuable. I am also certain that there are serious collectors out there with pristine examples in their collections. The world doesn't need mine for posterity's sake.

* What's not to like? The noise, the oil, the crazy rpm's, the simplicity, the cheapness, the quirkiness, the fun...

HalfaDave Thu Dec 15, 2022 4:40 pm

Hi pgang,
I Quote you:

What's not to like? The noise, the oil, the crazy rpm's, the simplicity, the cheapness, the quirkiness, the fun...

This IS what Cox flying is all about...

Firing up an old anemic Cox is still fun flying...

The potential energy of a NIB engine is just that.

Your old Coxes will still run good...

But... putting fuel to a brand new one...
Is more fun than, keeping it in the box.

Just my opinion,
Dave

GallopingGhostler Thu Dec 15, 2022 6:18 pm

To verify it is indeed a .051 and not a .049 with plastic red venturi base, the piston should have a groove machined in the lower skirt near the bottom.

https://www.coxengineforum.com/t4893-049-cylinder-and-piston-for-051#63392

OVERLORD on May 10, 2013 wrote:Here's a picture of the grooved piston to illustrate what SuperDave just said. Lieven [@OVERLORD]

If you look closely, you might see the slight appearing of the piston skirt bottom just barely being exposed at the start of SPI, at the lower end of the exhaust port opening.

pgang Thu Dec 15, 2022 6:49 pm

Yes it does have the grooved piston. I'm with you guys now - this engine would be better in a plane than in a box.

Here is another photo out of the box showing the cylinder, and a couple of other pics.

davidll1984 Fri Dec 16, 2022 9:29 am

[quote="pgang"]Yes it does have the grooved piston. I'm with you guys now - this engine would be better in a plane
But can also be in a car look at this one

Those .051 made Good power dont let it sit in a box use it I prefer to use them than to contemplate them but hey I do both Very Happy

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