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RE: Cox 049 RPM ??? - 11/26/2012 11:25 PM   
combatpigg



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Status: online 		I think an aluminum adapter could be made that fits around the Cox cylinder and make so that it slips fits into a Norvel muffler. I'll bet the Norvel muffler could be slyly restricted to pass a noise test. Pack it with a little spun fiber insulation, like a Cherry Bomb glasspack.
I think it was Richard Petty who made a intake restrictor plate one time that would pass tech inspection rules for CFM, but would melt away once the car got up to temperature.
IIRC they didn't allow very much CFM, either...much less than you might guess.


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RE: Cox 049 RPM ??? - 11/27/2012 12:43 AM   
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Status: online 		Today, I ran the A.C. Gilbert .074 Thunderhead engine. This is on Wildcat 15% nitro, Castor/Synth oil blend.

Prior to running it, I had to manufacture a glow head starter. I got the idea from Cox International's current glow starter, using a D-cell battery box. The aftermarket battery boxes come as 3 Volt, with the batteries in series. I had to drill out 2 rivets, to reorient the batteries in parallel for 1-1/2 Volts. Used an old 6-32 brass terminal screw salvaged from a worn out electrical switch. Used a pop rivet and rivet washer to fastener the spring battery terminal. I had an old universal glow head / glow plug clip. Can't tell if it was Veco, K&B, Perfect, Fox of what. Wiring harness is #16 multi-strand automotive wiring. It did the job.

The .074 runs a little erratic. After getting it to run, peaking it out a tad on the rich side, just touching the needle valve causes variations in speed. Looks like I may have to put a short piece of silicon fuel line over the thread and spray bar end, to stop air leakages.

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RE: Cox 049 RPM ??? - 11/27/2012 12:46 AM   
MJD



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Status: offline 		Cool! I picked one up from the classifieds a while back, "admired" it but not run yet. Any performance* numbers?

* or lack thereof?

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RE: Cox 049 RPM ??? - 11/27/2012 1:24 AM   
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Status: online 		I've to this day never seen evidence that one of the Gilbert .07s can fly a RC model....
I've got one too. It starts right up no sweat..but it has a standard glow plug tapped into the original head, plus a NVA that must plug up about 1/2 the "tunnel ram" intake. With the dual exhaust system hooked up it's a pretty bad lookin' hombre.
No performance numbers with mine, my tach doesn't go that low.


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RE: Cox 049 RPM ??? - 11/27/2012 3:18 AM   
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Status: offline 		Depending on the type of head fitted (and there seem to be about 3 of them) the element is often too cool. One of mine would only keep running with the plug leads connected. Don't over prop either-a 6x4 or 7x3 is about all the 07 will pull. [Interestingly,the actual Gilbert prop is a 7x3, with a massive hub that a spinner cone plugged into] The 11, of identical layout- is a much better engine and will run OK, but is no ball of fire.
In my old club (Christchurch MAC, NZ) there were several Gilberts in use by the vintage guys-and as CP indicates, they seemed to do better with the original glowhead tapped out and a normal plug fitted. I'm wondering-given the absolute rock bottom price these were sold for in the sixties, if the plug element is just simple nichrome, with no platinum or other precious metal component. That would explain their reluctance to keep running.........

See pics below-the 'high compression' conical head is the one I ran the 074 on-the others are spares acquired over the years-Tower was selling them well into the 1990s, off and on.

ChrisM
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PS the spinner nut on the 11 is not a standard fitting for the engine, it's one of the MECOA ones

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RE: Cox 049 RPM ??? - 11/27/2012 3:24 AM   
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Status: offline 		I just had to have one because of the cool cast intake.. it looks so trick, shame it's not on a killer engine.

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RE: Cox 049 RPM ??? - 11/27/2012 3:43 AM   
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Status: offline 		Here's the Gilbert prop I referred to earlier.........

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RE: Cox 049 RPM ??? - 11/27/2012 3:50 AM   
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quote:

ORIGINAL: MJD

I just had to have one because of the cool cast intake.. it looks so trick, shame it's not on a killer engine.



If the modelling mythology is true and they were developed for a range of RTF C/L models in the 60's, then its surprising they didn't sell more-in looks and eye appeal they are quite distinctive, and I can imagine in a suitably packaged RTF, just before Xmas, they might have been irrresistable. Alas Cox were simply too good in the market, and the Gilberts were destined to become a modelling curiosity, decades on. Mind you-how many of the Sportsman 15 powered RTF Comanches did Cox sell? I suspect that in that instance they overreached themselves-and what sells as an 049 concept doesn't necessarily work when scaled up.......or maybe it was just a pricing issue........

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RE: Cox 049 RPM ??? - 11/27/2012 7:01 AM   
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ORIGINAL: MJD Cool! I picked one up from the classifieds a while back, ''admired'' it but not run yet. Any performance* numbers? * or lack thereof?

Sorry MJD, I don't have a tach so that I can't answer. Power seems to be on par with a Cox Babe Bee. One thing I'll try later is run an APC 7x3 prop. With the larger displacement, I think it should produce the best thrust (at a lower RPM) with the larger prop. I was running a 6x3, which is recommended for break-in.

quote:

ORIGINAL: MJD I just had to have one because of the cool cast intake.. it looks so trick, shame it's not on a killer engine.

I've heard that the positive of this engine was easy starting. Apparently it makes a good sport engine, albeit a little on the heavy side.

quote:

ORIGINAL: ffkiwi If the modelling mythology is true and they were developed for a range of RTF C/L models in the 60's, then its surprising they didn't sell more-in looks and eye appeal they are quite distinctive, and I can imagine in a suitably packaged RTF, just before Xmas, they might have been irrresistable. Alas Cox were simply too good in the market, and the Gilberts were destined to become a modelling curiosity, decades on. Mind you-how many of the Sportsman 15 powered RTF Comanches did Cox sell? I suspect that in that instance they overreached themselves-and what sells as an 049 concept doesn't necessarily work when scaled up.......or maybe it was just a pricing issue........

Interesting observation, Chris. BTW, I found a link on the history of the A.C. Gilbert airplanes and engines at:

http://www.jitterbuzz.com/bill_tribute.html

They were a late comer in the market, and although they had a good product, it was difficult for them to get their foot in the door.

quote:

ORIGINAL: combatpiggI've to this day never seen evidence that one of the Gilbert .07s can fly a RC model.... I've got one too. It starts right up no sweat..but it has a standard glow plug tapped into the original head, plus a NVA that must plug up about 1/2 the ''tunnel ram'' intake. With the dual exhaust system hooked up it's a pretty bad lookin' hombre. No performance numbers with mine, my tach doesn't go that low.

In one of the forums, someone had used it to power a couple 1/2-A .049 airplanes, I think one of them was the Goldberg Junior Falcon, and it flew reasonably well with the engine. Unfortunately, I can't remember which forum it was posted in, may have been http://www.rcgroups.com. I don't have the mufflers you have, compatpigg.

One thing noticeable about the engine is the looseness of the crankshaft fit in the crankcase, causing some wobble during flipping. Yet when run, that wobble disappeared. Yes, the Gilbert is certainly not a powerhouse by any means. I don't have any additional plugs but I have a 1/4-32 tap. When the plug element goes, I'll drill it out and tap it for a regular glow plug. I'm thinking about putting the Glibert .074 in a 1/2-A CL profile plane. Now I understand why Scientific's 1/2-A's designed by Walt Musciano and a few others would specify ".020 to .074" in their 18" (460 mm) wingspan CL designs. Prior to having this engine, I thought an .074 would have been an overkill.

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RE: Cox 049 RPM ??? - 11/27/2012 7:16 AM   
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ORIGINAL: ffkiwi Depending on the type of head fitted (and there seem to be about 3 of them) the element is often too cool. One of mine would only keep running with the plug leads connected. Don't over prop either-a 6x4 or 7x3 is about all the 07 will pull. [Interestingly,the actual Gilbert prop is a 7x3, with a massive hub that a spinner cone plugged into] The 11, of identical layout- is a much better engine and will run OK, but is no ball of fire.

Chris, the plug that I have resembles the "trumpet" one you show, except that the steel plug ring is flush with aluminum combustion chamber, not recessed like the second one in your picture. This particular plug did do its job in the mid 40 degrees F weather we had this afternoon. After adjusting the needle, I disconnected the battery, it continued to run without problems.

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RE: Cox 049 RPM ??? - 11/27/2012 7:36 AM   
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Status: offline 		As I said earlier George-there seem to be at least three different head types..........

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RE: Cox 049 RPM ??? - 11/27/2012 7:53 AM   
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ORIGINAL: ffkiwi As I said earlier George-there seem to be at least three different head types..........

I'm not disagreeing with you, Chris, I was just stating an observation. I guess in this version of plug, which may be the latest, doesn't exhibit the cool running tendencies.

This is my first experience with the engine. I also have a Gilbert .11, one without the spring starter hub. I vaguely remember these engines being advertised in AHC's (America's Hobby Center) newspaper flyer some 30 years ago, something of the magnitude of $3 each. Now I wished I had purchased a couple.

A few in another CL forum felt that the Gilbert .11 Thunderhead was insufficient to power my 29" span (762 mm) Pilot Cessna 150 CL kit. Just curious, but how do you feel (or others) feel about that assessment?

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RE: Cox 049 RPM ??? - 11/27/2012 10:27 AM   
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ORIGINAL: GallopingGhostler

I'm not disagreeing with you, Chris, I was just stating an observation. I guess in this version of plug, which may be the latest, doesn't exhibit the cool running tendencies.

This is my first experience with the engine. I also have a Gilbert .11, one without the spring starter hub. I vaguely remember these engines being advertised in AHC's (America's Hobby Center) newspaper flyer some 30 years ago, something of the magnitude of $3 each. Now I wished I had purchased a couple.

A few in another CL forum felt that the Gilbert .11 Thunderhead was insufficient to power my 29'' span (762 mm) Pilot Cessna 150 CL kit. Just curious, but how do you feel (or others) feel about that assessment?


George-I wasn't getting at you. There could well be more head type variations-I know from personal experience that there are at least three distinct types-because I have them-but not what order they evolved in-nor if they have the same kind of element. I'm not 100%certain-(because my spares are not all located together) but I don't think there was the same sort of variation with the 11 heads. I have two 07 and one 11-one of the 07's with that horrible grotesque spring starter hub. Both sizes were also produced in a cheap 'gold' finish which soon went a horrible brown-and some versions had a moulded nylon tank which was suspended below the intake.

Very little if any performance data has been published on either, though Peter Chinn did conduct some testing-and mentioned this in his 'Engine News' column in 'Model Aircraft' around 1963 IIRC, but did not give specifics other than to mention that they both revved much higher than one would have expected from the piston port induction layout. I find the absence of any published report telling-as he obviously did some testing-perhaps the results were so disappointing either he, the manufacturers or the magazine-decided to withold them.

You might have to do some testing of props, but I'd expect the 11 ought to fly your Cessna-though of course a lot will depend on the weight of the model, the line length and diameter etc. Given that these engines don't seem to be able to swing much prop load, perhaps a 7x5 might be a good place to start?

The main exponent of the Gilberts in my old club(as alluded to earlier) was/is (he's still with us-but at 91 years old doesn't fly any more......) a guy called Ian Henry, and he used them in vintage FF designs like the Civy Boy, Civvy Hearse etc-though I don't recall the exact size of the model. I saw those fly on numerous occasions-and they didn't seem short on power-but Ian may well have scaled the design proportionately to suit the engine......

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RE: Cox 049 RPM ??? - 11/27/2012 2:20 PM   
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I've heard that the positive of this engine was easy starting. Apparently it makes a good sport engine, albeit a little on the heavy side.


I wonder if Cox (actually Mike Dorffler at Estes, RIP) thought the Sure Start concept was original?


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RE: Cox 049 RPM ??? - 11/27/2012 2:34 PM   
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ORIGINAL: ffkiwi There could well be more head type variations-I know from personal experience that there are at least three distinct types-because I have them-but not what order they evolved in-nor if they have the same kind of element. I'm not 100%certain-(because my spares are not all located together) but I don't think there was the same sort of variation with the 11 heads. I have two 07 and one 11-one of the 07's with that horrible grotesque spring starter hub. Both sizes were also produced in a cheap 'gold' finish which soon went a horrible brown-and some versions had a moulded nylon tank which was suspended below the intake.


Chris, I think you're earlier statement may be spot on. This is what is stated by one supplier of glow heads on E-Bay, in listing:

E-Bay - AC Gilbert American Flyer 11 model engine glowhead

Gilbert made 3 different variations of glowhead, 2 machined out of aluminum, and one diecast white metal.

quote:

Very little if any performance data has been published on either, though Peter Chinn did conduct some testing-and mentioned this in his 'Engine News' column in 'Model Aircraft' around 1963 IIRC, but did not give specifics other than to mention that they both revved much higher than one would have expected from the piston port induction layout. I find the absence of any published report telling-as he obviously did some testing-perhaps the results were so disappointing either he, the manufacturers or the magazine-decided to withhold them.

I think it was just a polite way of not giving any negative impressions for this engine. When a .074 produces about the same power as a well established Cox Babe Bee .049 or Wen Mac .049, it certainly won't make any sales unless there is a notable trait to its merit, such as, "swings a larger prop with authority".

quote:

You might have to do some testing of props, but I'd expect the 11 ought to fly your Cessna-though of course a lot will depend on the weight of the model, the line length and diameter etc. Given that these engines don't seem to be able to swing much prop load, perhaps a 7x5 might be a good place to start?

I think it would be a good starting place. Another may be an 8x3 or 8x4 prop.

quote:

The main exponent of the Gilberts in my old club (as alluded to earlier) was/is (he's still with us-but at 91 years old doesn't fly any more......) a guy called Ian Henry, and he used them in vintage FF designs like the Civy Boy, Civvy Hearse etc-though I don't recall the exact size of the model. I saw those fly on numerous occasions-and they didn't seem short on power-but Ian may well have scaled the design proportionately to suit the engine......

For any engine, there is always optimal proportions. It sounds like Ian knew his stuff and made the best use of its traits. The instructions with the Gilbert mentioned for break-in, "Use a 6" dia. x 3" pitch, or a 6" dia. x 4" pitch Propeller on the .074 Thunderhead, and a 7" dia. x 4" pitch, or 8" dia. x 3" pitch Propeller on the .11 Thunderhead."

Similar to the lower compression Fuji 099S-II, I'm thinking these engines probably do well on a slightly larger diameter, lower pitch props, which work well with Texaco type slow flyer aircraft. I think after break in, the .074 may work well with a 7x3 prop, but I'll know more when I try it.

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RE: Cox 049 RPM ??? - 11/27/2012 3:49 PM   
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ORIGINAL: MJD I wonder if Cox (actually Mike Dorffler at Estes, RIP) thought the Sure Start concept was original?

I really don't know the history of the Sure Start, except for my history: two engines I purchased about 7 years ago from Estes' closeout sale for $7 each.

The addition of the choke tube supposedly made these easier to start. I'll know more when I get them mounted in a plane and run them. I've had no problem starting all the other .049 Coxes without a choke tube. I guess this just made it easier to Sure Start.

I'm thinking mounting these possibly in a CL twin, may be the F-82 Twin Mustang by Walt Musciano or Germany's A.E.G. G-IV / UK's DeHavilland DH-10 profile bomber bipes from Hip Pocket free plans website plan, World War I Monsters and Monoplanes CL plan. From a local hardware store, I picked up 3/8th in. (9.5 mm) long nylon spacers. These spacers will allow me to mount the engine without having to recess the choke tube into the firewall (see attached, motor has exhaust restrictor throttle and 1" or 25 mm Ace R/C spinner installed).

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RE: Cox 049 RPM ??? - 11/27/2012 5:08 PM   
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Status: online 		After gathering some run time on the Gilbert .074 Thunderhead with Master Airscrew 6x3 prop, I tried the APC 7x3 prop. I installed a short piece of silicon fuel line over the needle / spraybar joint (attached photo), which cured the erratic needle. The APC has no trouble turning the 7x3 prop, which I'd expect. AFAIK, the original prop was a fat blade 7x3. The engine has good bark but it is certainly a lower pitch whine than an .049. My guesstimate would be around 11,500 to 12,500. This is on Wildcat 15% with Castor at this 4,300 feet (1,311 m) elevation. Without a tachometer, I can't quantify the performance, but with the larger prop should be fine for any aircraft designed for an .049 reed valve. YMMV.

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RE: Cox 049 RPM ??? - 11/27/2012 6:06 PM   
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ORIGINAL: GallopingGhostler

quote:

ORIGINAL: MJD I wonder if Cox (actually Mike Dorffler at Estes, RIP) thought the Sure Start concept was original?

I really don't know the history of the Sure Start, except for my history: two engines I purchased about 7 years ago from Estes' closeout sale for $7 each.

The addition of the choke tube supposedly made these easier to start. I'll know more when I get them mounted in a plane and run them. I've had no problem starting all the other .049 Coxes without a choke tube. I guess this just made it easier to Sure Start.

I'm thinking mounting these possibly in a CL twin, may be the F-82 Twin Mustang by Walt Musciano or Germany's A.E.G. G-IV / UK's DeHavilland DH-10 profile bomber bipes from Hip Pocket free plans website plan, World War I Monsters and Monoplanes CL plan. From a local hardware store, I picked up 3/8th in. (9.5 mm) long nylon spacers. These spacers will allow me to mount the engine without having to recess the choke tube into the firewall (see attached, motor has exhaust restrictor throttle and 1'' or 25 mm Ace R/C spinner installed).


Essentially it gives you access to the intake for choking or priming, so it can help. It can also be tempting to flood the engine with an over-exuberant prime into the intake.

Go to it with the Ace spinners, but I bought one years ago and quickly ditched it - it produced a lot of vibration. "YMMV"

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RE: Cox 049 RPM ??? - 11/27/2012 6:35 PM   
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Status: online 		MJD, on the Ace spinner, I haven't observed the vibration you are referring to. Could it be that yours has either a molding or machining (drilled hole off-center?) defect? I've used it on the reedies (slightly lower RPM's), so can't vouch for Tee Dee's.

Yes, I can understand that issue on flooding during "choke". Done it too many times to mention on the larger crankshaft valve engines.

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RE: Cox 049 RPM ??? - 11/27/2012 7:24 PM   
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Status: offline 		Over the years I have become very particular about spinners and prop balancing. Mine was probably a bad example, if yours works then great! I started investing in spun Al spinners for almost everything a while ago.

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RE: Cox 049 RPM ??? - 11/27/2012 10:33 PM   
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Status: offline 		George-I'm pleased to play fairy godmother this morning [it was either that or get driven mad by all the 'Hobbit' movie premiere hype from all the various media!....yes the world premiere is here today-starting at 7pm. The whole damn city has gone half mad..........]

Anyway-following on from my comments yesterday I've done some test running of the Gilbert 074 this morning (its a lovely spring morning-and no boots or heavy objects have come sailing over the fence yet-so it seems I haven't annoyed the neighbours enough yet....................)

I note for your interest (and anyone else's who may be interested) the following points: (fuel was 15% nitro-20%castor-this mix was chosen so it was as close to your fuel as possible.It was pretty old fuel though-so figures might be improved on a fresh batch!)

(1) The engine starts very easily by hand. Unfortunately-in common with reed valves and other sideports-it starts backwards just as often as forwards. It is noticeably slower backwards-not unexpectedly, as there is no thrust washer or any means of absorbing the crankshaft end loading when running backwards.
(2) My original 'conical' head let me down once again-and would not run without the battery connected-even though the element showed a good healthy glow. It ran a struggling 6000+rpm on the 7x4. I changed to one of the 'truncated trumpet' heads and had no further problems
(3) Needle setting on the large props I found to be critical-a click either way on the ratchet and revs fell right off. This characteristic disappeared on the 6" and smaller props
(4) The engine is prone to vibration if there is the slightest prop imbalance or poor prop centre-ing.
(5) The engine runs very hot-despite the 'rattling good fit' of the crankshaft.........
(6) Starting was pretty much the same hot or cold (ie it didn't deteriorate when the engine got hot
(7) The engine stops easily with a brief touch of the finger to the intake-I did the whole test on about three 10cc tanks, stopping part way through each tank to change props

results: Taipan 7x4 white nylon 9,200rpm
APC 7x3 rigid 11,300rpm
Cox 7x3-1/3 black 10,400rpm
Master 7x3 rigid 12,100rpm
Master 6.5x3.5 10.800rpm
APC 6x3 rigid 15,200rpm
Cox 6x4 grey 14,300rpm
Cox 6x3 grey 15,600rpm
Tornado 5-1/2x3 nylon 16,800rpm

These figures show that the engine is not the dog a lot of people think it is-but it is clearly not too good on bigger props-6x4-6x3 and perhaps the APC and Master 7x3 sizes seem to be about the best. The engine ran particular well around the 14,000-15,000 mark and was easy to set at that rev band. I think Peter Chinn was right-potentially the 07 would run up to close to 20,000rpm on a small prop-the Tornado needed more attention to balance and centreing-so most of these figures might be improved upon.

I think providing it is used in 049-06 sized C/L models it will be adequate-it is certainly no Norvel!

The hot running concerns me though-I don't know how the engine would handle runs of 5-10 mins in C/L or R/C models-and if this hot running was typical-then I can see there might have been problems when installed in the moulded plastic RTF C/L models it was made for-potentially melting the cowl mouldings or distorting the engine mounts.

ChrisM
'ffkiwi'


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RE: Cox 049 RPM ??? - 11/28/2012 12:09 AM   
MJD



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Status: offline 		If anybody is all exceited about one of these engines now, check it out:

Gilbert .11

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RE: Cox 049 RPM ??? - 11/28/2012 12:51 AM   
skaliwag



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Status: offline 		RARE, CLASSIC - VINTAGE fishing weight.

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RE: Cox 049 RPM ??? - 11/28/2012 12:58 AM   
combatpigg



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Status: online 		Are there any examples of sleeve induction engines that made better power in this size range..?


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RE: Cox 049 RPM ??? - 11/28/2012 1:15 AM   
ffkiwi


 

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Status: offline 		Fox Rocket 09? Its the only other glow sideport I'm aware of. Of course you have the Mills 1.3cc (or its 1.5cc Indian derivative) which is an .08-and the Jena 06 -another diesel-and both come into their own turning big props at lower revs.

ChrisM
'ffkiwi'


PS FWIW I've seen a sideport conversion of a TD 049 sold on Ebay. Why someone would bother to convert a TD to sideport utterly escapes me...........see pic below

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