ONE RUBBER POWERED KIT THAT REALLY BLOWS!

 

FOREWORD: Many thanks go to the author, Dr. Roger Simmonds from the UK who was so gracious to let me reprint it. He runs JETEX.org, and is editor of their house organ, SMOKE TRAILS. [Link at the bottom]

Jetex model flyers are much akin to we CO2 engine holdouts and record album enthusiasts inasmuch as trying to keep their interest functioning long after their products ceased to be manufactured. Keep the faith, brothers!

 

 . . Unfortunately, the model, ‘pukka vintage’ semi profile period piece though it is, is more than a little ‘agricultural’ and unappealing. A ‘turboprop’, then, is not such a good idea: is there a proper scale subject out there which features a jet and a propeller - one perhaps originally with mixed power units that fulfils my requirements. There is a nice modern design – Richard Crossley’s Curtiss XF-15C for rubber and Rapier L1 (Smoky Addiction 4) - but I don’t  know of any 50’s design with a diesel engine and a Jetex motor. However, there was one curious ‘dual power’ kit marketed in the US just after WW II:

The advert has appeared before in these columns (Smoke Trails 12). Ben Nead had wondered if the model was a figment of the copywriter’s imagination, as he had never seen one. Well now he has, and acquired one for his extensive collection of Ray models. Generously, he sent me scans of the plan and wood. At first sight, after I had pieced it together, the plan looked to be a very nice job, but closer inspection revealed some distortions and a 13 mm (½") disparity between the top (plan) view and the side view. Were these in the original, I wondered, so I asked Steve Bage to wave his magic ‘CAD wand’ over Ben’s scans. Steve writes: ‘The plan has an unmistakable ‘Ray’ look about it, and there are indeed a number of issues. The fuselage is significantly shorter in the side view than in the plan view and the printwood matches neither! I’ve stretched the side view a bit, it’s probably still a few mm short, but near enough for a toy airplane purposes. I’ve fixed the fuselage keels to match the plan view. 

It looks as if Ray had taken a paper copy, cut it up, and re-pasted all the bits together in a new layout, probably to make room for the photos. They used to do this quite a lot in those days. Some bits were not square and there were a couple of tell tale marks where things had been moved. The ribs also look rather an odd shape, but I’ve drawn them just as they are. Other than the fuselage keels I.ve not checked the print wood or die cut (or should that be die crushed) wood against the plan. I’ve squared up the bits best I can so I’m pretty confident that this version of the plan is better in a lot of ways than the original, but a few more ‘challenges’ will surely come to light during a build, so builder beware! Thank you Steve.

  

I’m sure Ray employed competent draughtsmen, note the fine perspective drawing below, and the inaccuracies are by no means unique to Ray. As any committed SAMmite knows, old plans can contain lots of errors which these days become very obvious when plans are ‘digitised’. Fortunately, correcting them in the digital domain is relatively straightforward. When building in the old days, I remember, we took these errors, distortions, etc, in our stride, ‘bodged’ our way around even quite large ones, and just carried on! 

About the design itself, Steve asks how one was meant to prepare and launch the ‘dual fuel’ model. Hmmm, a very good question, best answered by a quote from the (comprehensive) instructions: “First fly with the rubber motor only until you have the ship [sic] in trim. Now for a real dual power flight. Insert the rocket [CO2 bulb] in its tunnel and wind the rubber motor. One person must hold the plane in his right hand and with his left hold the propeller from turning. The second person carefully engages the gun squarely on the rocket unit. The person holding the plane gives the signal to fire the gun and launches the plane in a normal manner. The breathtaking climb that follows will give you a new thrill in model flying”.  

Despite the reservations, the Ray Fireball is a very nice design. Lindsey Smith is better able than I to assess its scale accuracy, but it looks good to me and one would of course (as Ray

themselves recommend) not bother with the undercarriage. It may be just the model I’m looking for. Reducing the span to 16-17 inches would make it suitable for one of Atomic Workshop’s little electric motors. They suggested a Voodoo15/25 with either a 90mAh or 130mAh LiPo (see atomicworkshop.co.uk). Building this vintage design essentially for electric power, I can incorporate a mounting tube for a Rapier, deepen the trough and cover it with foil. All initial flight resting would be under electric power, and a Rapier lit up as and when. Should make for a stirring sight! One thing still bothers me: I wonder just who was responsible for that name. Given the prototype had a very new and unreliable turbojet, the sobriquet cannot have inspired confidence in the test pilot. If we ever do see Rapiers again, and if they are as (un) reliable as the 2008/2009 varieties, any ‘authentically’ duel-powered Fireball could end up being just that!

LINKS

The original piece at Jetex.org - - - SMOKE TRAILS #27

BOTTLE BABY EPISODE I

 

With CO2 modelers, sooner rather than later there comes a time when the original method of charging the CO2 tank becomes apparently sub-optimal ~ in cost, in efficiency and in availability.

  When I first started to write this, it was to give more detailed advice to CO2MFer Steve who is considering the jump from cartridges to paintball bottles. The first draft of that went 6 paragraphs of the history of non-standard charging nozzles and I hadn’t still mentioned paintball CO2 bottles. So I’ll save that stuff for Bottle Baby Episode II, coming soon.

  Paintball bottles are used in the sport of Paintball to facilitate an external and tool-less interchangeable CO2 reservoir for paintball guns. They come in a variety of sizes (capacities) from 12 oz to 28 oz and sometimes larger. Co2 is sold by the pound and is dispensed in a mixture of liquid and gas depending upon temperature and volume. More on this later.

  These bottles can be found online and at some sporting goods stores and of course at Paintball parks, which usually have an on-site store not unlike a golf course pro shop where you can buy balls, clubs, spikes, and lime green Republican pants. A 20oz bottle will run you maybe thirty bucks.

  Of course, you can get these from Amazon for a few bucks less, but I want you to consider this. First ~ where are you going to get it filled? Your local paintball supplier is a struggling small businessman and is eager to keep you as a customer. You better believe he’s tired of yahoos coming in for full service for something he bought somewhere else. (Curiously, better than 60% of Them look like Eddie Vedder.)

Offer to buy two bottles if he’d fill them as part of the deal. His cost for the CO2 will be less than a buck, and you go home ready to fly, and cost-wise you probably end up on the + side of the deal. Next time you go to get them filled, take a couple of engines or models. I guarantee he will be fascinated by these, and he probably wants to see them run. There’s a guy in Sacramento at a paintball store that let me have gratis a few of these tiny, tiny used brass check valves from CO2 pistols for my evil experimentation. You’re building a relationship here that benefits you both. Dick’s Sporting Goods used to fill paintball bottles, but the ones in the dipshit republic where I live, California, stopped it when some shopping centers took a brave and principled stand against gun violence and banned stores from selling guns, ammo or anything resembling the same. So as a business model they’d rather sell shoes fabricated by 7-year-old “political” prisoners and religious slaves in China. Honestly, it’s enough to give hypocrisy a bad name.

Another good thing about buying from a B&M store is you can check to see if your bottle is “fresh.” On every bottle is a hard-etched date of manufacture₁. It is illegal to recharge the bottle if that date is more than five (5) years old. Most of those discount bottles you get off Amazon or EBay are discounted for a reason ~ a substantial chunk of their service life is effectively over. A bottle with an etched manufacture date of 2 years ago has 40% of service life taken away. If all he has a bunch of bottles no “fresher” than a year, he might give you a price cut, even more if you buy two. You’re building a relationship here.

The adapter can currently be found at Old Engine Bazaar run by Jiří Linka and runs roughly around 34 bucks. [link below] His service and shipping time is excellent and accepts PayPal or direct charge. While you’re at it pick yourself up a Gasparin motor for your next rig. It has a nozzle for the 2mm nipple used on most post-80s American engines and most if not all European makes. His listing says it’s for “US 12OZ bottle use for Paintball” but fits all size paintball bottles; the threaded valve is the same for all.

So, after all this, you ask yourself “Self, 35 bucks for the bottle, 5 bucks to fill it, and 40 bucks for the adapter, ain’t that a bit much, and isn’t talking to yourself a little disturbing?” Here’s the math ~ all the above is about eighty bucks. Let’s say you don’t cool your bottle first and only get 25 oz of co2 in your 28 oz bottle. Twenty-five ounces of CO2 is the equivalent of 708 grams of CO2 or 88 8-gram cartridges. A fifty-lot of Mr. Fizz cartridges on Amazon right now runs $27.99. [0.07¢ per gram]. So, to buy an equal amount as the 25 ounces you bought for 5 bucks in the paintball bottle would cost you $49.50 in cartridge form. Anyone who has used cartridges for any length of time knows the whole cartridge is rarely efficiently used, three full tank charges are usually the best one could hope for, so the effective amount of full aircraft tank charges optimistically be 80% of the theoretical quantity available. So maybe it’s a draw. UNTIL . . . your second charge of the tank ~ five bucks. The cartridges will still run you $49.50, again and again. So, at the second tank charge you’ve spent 85 bucks and have the tank and adapter, or you’ve spent 99 bucks and have 88 empty steel cartridges and 88 full.

So visit your local shop and get your first bottle and have it filled. While you’re waiting for your adapter to arrive, store your bottle in your fridge upright. Next time you have it filled, freeze it for a few hours and take it to the paintball store in a cooler or wrapped in a blanket. You’ll get a lot more liquid CO2 in the bottle the colder it is.

When this bottle setup paid for, maybe consider buying a smaller (12oz) bottle to have handy when your main one goes empty, to afford you some time to get to the PB store at your leisure for a refill.

Well good luck. Any questions feel free to ask. Here is the link where you can buy the adapter ↓

 

PAINTBALL BOTTLE ADAPTER

 

 

NOTES

₁ Check to see if the empty weight of the bottle is etched upon the bottle as well. If not, ask if Eddie Vedder can weigh it empty before he fills it. Write that weight down and tape it to the bottle when you get home.

₂ Got friends or a flying club interested in flying CO2 motors also or do you live far away from a place to fill your bottle? Consider a 5 lb. tank. (A 2 ½lb tank is also available, but generally they cost more than twice the 5lb size. Go figure.) A 5lb tank on Amazon runs $60/free ship. Now you have a much wider base of refill places available to you ~ welding gas suppliers, aquarium fish suppliers, home brewer suppliers and probably more. The valves assembly to connect to the paintball tank is about 50 bucks. But it holds the equivalent of 283 CO2 bulbs. Yowza! Be sure to have it filled just before the expiration date, its been known that modelers have had the 5 year tank expiration run out before the tank is empty!

Well that’s the basics of using Paintball tanks for charging Co2 model engine systems. If I have left anything out, please comment below. I have left out any discussion about SodaStream™ bottles as they are more or less a different method requiring different equipment and has its own pros and cons.

 

 

2021 SO FAR ~ ALL THRUST AND NO VECTOR

 

So, after a period of “monotonous languor” I’m trying to get some things accomplished, CO2 wise. First thing, after the passing of model designer, author, and columnist Bill Hannan I thought I would build a CO2 powered version of the aircraft he was most associated with ~ the Nieuport 4. I planned on using a Brown MJ-70 or B-100. So, I enlarged the plans of the rubber-powered Peanut plan he drew by 138% to make its span a little over 18 inches. After I got the fuselage sides framed, I started to do some thinking. The original aircraft had a rotary engine, and the plans he drew just had slab sides and no engine detail to tell of. Flummoxed I was.  

Then the scales fell from my eyes. This plan was a model, not of the original plane, but of the 36-inch wingspan model kit made by Ideal back in 1913. Ideal also made kits for the Wright Flyer, Curtiss Jenny and the Bleriot XI, all lacking in detail and only basically representative of the original full-size craft. 

  So I’m going to put the brakes on this for now, in search of a better plan. But I do want to make a Nieuport 4, if only to decorate it with a W C H like the masthead of his column “HANNANS HANGAR" which was the first page I turned to when I got my Model Builder in the mail every month.

If you try to reach me at the e-mail address co2@buztruckindustries.com, I will be changing over by the end of the month to the address co2parts@yahoo.com. Go Daddy has become such an execrable business model I could do better with a “free” e-mail for now. As usual, feel free to contact me with your questions at the new address.

I’M READY FOR MY SCREEN TEST, MR. WEINSTEIN

I’M READY FOR MY SCREEN TEST, MR. WEINSTEIN

6 October 2020

When things go wrong with your CO2 engine’s operation, there is a host of malfunctions or complications that could be at fault. In some cases, the same symptoms may be caused by one of two separate but distinct malfunctions. Let’s face it, troubleshooting a CO2 engine can be a frustrating task.

Generally, these can be broken down to two basic conditions: CO2 [liquid or gas] is going somewhere where it shouldn’t, when it shouldn’t: or CO2 is not going somewhere when it should. It’s this second case I’ll be addressing here ~ the unseen neglected charger screen.

Let’s describe a scenario ~ when you put a fresh CO2 cartridge in your charger for your first flight of the summer.* You poke that charger on the filler for about 60 seconds for a good charge. Removing the charger, you get a good pop, flick the prop and nothing happens – or maybe a little popcorn fart of a run. Now, the most important thing to do is nothing. Light a smoke and think. I can think of a few system problems that may be manifested here. I’ll address some of the others later, but now we’ll focus on the screens.

In the MODELA, GMOT and Brown Jr. chargers there is a brass screen in the plumbing system. Its purpose is to protect the integrity of the engine’s plumbing and to stop metal, corrosion and paint from nicking, scoring and otherwise wearing of the plastic and chromium plated surfaces of the check balls. In one flying season, a scratch on a chrome-plated ball, during all the wide temperature swings from sub-zero to hot day, expanding and contracting that scratch will soon cause a void in the plating and flakes will soon evolve from the void, and be ingested further in the engine, abrading other parts, metal and plastic alike. The screen usually does a suitable job stopping these particles.

The Brown screen is found in the bell portion of the brass filler.
It’s hard to see, especially if it is older and covered with crud. If it’s bright and clean, reassemble the filler. Make sure the filler’s stopper stick or ball can move and not stuck. If you can, unscrew the tank fully from the system and with the charger, shoot a brief blast through the filler to ensure the gas flow is not impeded between the filler and the tank. Why? While not strictly scientific method, CO2 motor troubleshooting is most efficiently accomplished by moving from the known to the unknown.

The MODELA/GMOT style charger on the other hand, has its crap-trap in
the head of the charger. To access it, unscrew fully the head from the charger body. There is a slot across the head, use the GMOT charger wrench, if you have one, to unscrew the retainer nut. Pull out the rubber neck seal and piercing needle and voila! there it is. Unlike the Brown screen which is a single
circle of brass screen, the GMOT style is a screen sandwich with the “buns” being two 9mm circles of brass screen with a similar diameter section of some fibrous material.

Add caption

I have seen many Modela and GMOT spares kits, but never one including this piece. (If I was to try to replace this material, I would start with some sort of synthetic material used for air filtration. Cotton or wool I believe would be more prone to retain moisture.) Maybe, and this is just speculation, it might help diffuse any liquid CO2 before it heads down to the cylinder. Maybe only Dr. Modela knows for sure. Like the Brown, clean or verify it’s clean, reassemble and make some sort of gas flow check.

So here we are. We don’t know why our motor is misbehaving, but we at least know it’s on the engine side of the screen

*Usually you neglect to clean, dry and oil and wrap your engines in paper for the winter, as most of us, at the time, rarely think the last flying session as the last one of the summer. Time and moisture around copper and brass in an enclosed system is inviting corrosion. Take care of those screens, will ya?