Cox engine bargains.

nitroairplane wrote:

Carl wrote:you dont see those "w" or "m" filament glow heads much. I remember back in about 1978 a club buddy brought in a bag of about 10 or so glow heads each packaged in a cardboard bubble pack. He said they were 20 years old then so that means they were from the 50s doesnt it? We ripped open a few packs and noticed they all had this odd filament design. i think I noticed a drop in performance and the glow heads didnt last very long as the top arch of the m or w would burn out. if that glow head you have there is still working, chances are the engine hasnt been used very much.

Where they only made like that to be cheaper and easier to manufacture or were there other reasons behind the design?

microflitedude wrote:

nitroairplane wrote:

Carl wrote:you dont see those "w" or "m" filament glow heads much. I remember back in about 1978 a club buddy brought in a bag of about 10 or so glow heads each packaged in a cardboard bubble pack. He said they were 20 years old then so that means they were from the 50s doesnt it? We ripped open a few packs and noticed they all had this odd filament design. i think I noticed a drop in performance and the glow heads didnt last very long as the top arch of the m or w would burn out. if that glow head you have there is still working, chances are the engine hasnt been used very much.

Where they only made like that to be cheaper and easier to manufacture or were there other reasons behind the design?

Once again they were trying to lower production costs. Performance was lower than the standard glow heads, and they lost an ensuing patent to either Atwood or Holland engines. Thus the low production runs.

Mudhen wrote:Hi Fellas,
Although I can’t be 100% sure, I don’t think the “W” element glowhead was discontinued because of patent infringement. Follow me:
The following information is related directly from Cox “Engineering Change Letters/Order,” (“ECL’s, or “ECO’s.”) ECL/O’s are a great source of information, though not the only source, because they come straight from inside the company. The letters are dated, numbered, signed, and each provides a brief, written description of the work carried out by Engineering.
Beginning June 22, 1971, Cox began work on a “Cam Roller Starter Assembly” for the “350-9” Babe Bee engine intended for the “Rivets” model airplane. Several ECO’s describe changes and modification to the starter until 7/12/1972. This ECO notes, “Clutch type starter assy to be discontinued as per Bill Selzer memo dated 7-10-72.” The letter also notes the remaining starters are “total scrap” costing the company $15, 665.08. A hand-written breakdown of the losses is attached to the ECO. I don’t have the “Bill Selzer memo” but a little digging in fact reveals the patent infringement with Wen-Mac, (or Testors, or AMF, not really sure.) The point is that work was immediately halted and the remaining stock was scrapped. This would be consistent if Cox were ordered to “cease and desist.”
The “W” element glowhead – I searched the U.S. Patent database for a “W” element glowplug/head and found nothing. That’s not to assert it wasn’t patented, I just couldn’t find anything. On July 31, 1969, the ‘“W” Glow Plug (short reach)’ ECL indicates that the “W” element glow plug was released and scheduled for production. I heard it was Cox engineer Bruce Paton who came up with the idea for the element, but that Bill Atwood actually designed it. This particular ECL is signed, “Wm E Atwood.” On 10/31/69, the “witness mark,” or groove, was added to the upper cooling fin. 3/28/72 – the witness mark was removed. The former stock of coil filaments was depleted so the mark was no longer required for identification. 11/17/72 – The ECO reads, “ 302-5 ‘Coil’ filament will replace 271 ‘W’ filament as soon as stock is exhausted.” The point here is that if it were patent infringement, then a “cease and desist” order would have been issued. Rather than waiting until “stock is exhausted,” Cox would have been forced to scrap the stock and take the losses, similar to the rewind starter debacle.
Anyway, I don’t think it was patent infringement. It may have been an attempt to reduce cost. If the “W” element was less successful because of reduced engine performance, then it makes sense why Cox returned to the coil filament.
Mud

Mudhen wrote:

Admin wrote:So Mud, from your research and data, there is a good chance my glow head originally came on the 290 or at least not original to the babe bee it was on.

I'd say the glowhead is correct for your Babe Bee. According to the ECO the witness mark was added in October, 1969 and removed in 1972. Your Babe Bee and 290 both fit that time frame.
Mud