Yeah, but that is one bulky looking conversion on the 220... looks even worse when you see a walbro hanging underneath the OS 160 boxer... The glow carb conversion, working properly of course, I think is the better way to go... no diaphragms to service, virtually maintenance free... just need to sort out the tank pressure, and get rid of that crap trap.

Could be, but the black plastic ones are glass fiber re-enforced nylon... most likely just a color change, black looks better than the silver / grey... you would be surprised how much a company will invest in the appearance of their products, just a change in the color, can influence sales.

Boxer only, and IF both exhausts connected via T-connection to the tank only, you can leave out the craptrap, IF you are willing to replace the feltclunk about every year or so.
All other engines, I would not do so, but guys, a bit of ingenuity makes a craptrap a total non-issue: the one in this vid is 100% maintenance free (non aerobatic, though).

Just let your imagination run wild, that's how the best ideas are conceived (the worst ones too, but let's forget about those )

Hey Fellas,

Anyone familiar with the Byron Husky? I have found one NIB and wondering if it would be a good fit for the 1.60

Boxer? Think it would be a bit light on power but I have found people saying it does work. The weight is kind of a concern but basically its a 20 lb 1/4 scale cub with flaps..

Chris

I would have to find another airframe to even consider doing another project with a gas converted boxer... I'd get a used OS or ASP boxer and convert it over to gas.... put it in another ARF, maybe a sig Rascal 110", flying weigh around 13 pounds.


That looks very similar to my PA18... there is a youtube video of the same H9 PA18 I have flying with the OS 1.60 boxer ( glow ign ), and it seems to fly very well... weighs around 18 - 19 pounds... if you can keep the weight down, that husky will fly scale like, or a bit better than scale with the gas conversion.... My 1/4 scale Sig J3 cub weighs just over 21 pounds wet, flying with the OS 1.60 boxer on CDi glow fuel, and it performs all the basic aerobatic maneuvers... I would say its just about balanced power to weight, but doesn't feel under powered the least.

It should most definitely fly, my Big lift weighs 14,5 lbs (6,5 kilo) and has no issues towing about 8 lbs gliders. Perhaps you need to give a bit attention to the cooling air (baffling, and it needs to be effective, not just a "bulkhead" around the engine), because the engine definitely needs to work a bit.

It would not be my first pick, because that combo is not "unconditional".
If I had to do some estimates, that husky will absorb around 1, maybe 1,5 hp in level flight, and from my experience the open and exposed twin is capable of over 2,2 WOT up to about 1 minute, and at least 1,5 sustained indefinitely. Properly baffled engines cool better than open and exposed ones, so done properly, there are no issues whatsoever, but that is the condition: "done properly".

Mind you, I am careful in my estimations, probably the limits of sustained operation are wider, but I would hate to see somebody wreck an engine "Because Brutus said it could be done".

It would be light on power compared to the engine recommendations (the ST2500 on meth has more power than the OS/ASP twin on gasoline) but I am pretty confident it will have enough power for safe flight. It will be a bit sedate maybe. I think, I would like it for those endless no-wind summer evenings.

The 110" Rascal would be an extremely safe bet. The Rascal requires less than 0,5 hp for sustained level flight. You would have about 400% excess power. It would be bordering on "unlimited vertical".

My 15.5 lb 1/4 scale J3 flies nicely with a 26cc 2 stroke gasser. A little more than scale power, nothing close to unlimited vertical but I don't have to cut loops unreasonably short at the top. A suitable gas converted 4 stroke single might be something like a Saito 220 (36cc). With glow or gas I add 50% to the recommended 2 stroke to size for 4 strokes. My 220 is slated to power my 1/4 scale Taylorcraft Clipped Wing when I get it running right. Similar weight to the Cub.

If that Husky ends up weighing 19-20 lb I would be looking for a bigger engine than an OS 160 twin, even on methanol. That's just me though.

Depends also a bit on the altitude you live at, I guess.
A 26 cc 2-stroke gasser (I am assuming a zenoah here) is in normal trim and common used props like 18 x 8 not all that more powerful than the OS/ASP. Don't get me wrong, it absolutely IS, but not shockingly so. Not like "twice as strong" or anything like that...
I mean, I know you can get 3,5 horses from that Zenoah, but for that it needs to run 10~11K, and that is not an RPM you want to fly around with. Starts to sound obnoxious. 3 hp, or perhaps slightly under, is more realistic. I have seen 2,4 hp from my ASP twin, and in flight it exceeds that even.

It's an Cermark SPE 26 on my 15.5 lb Cub. Not the strongest engine out there, but I'm not trying to fly a 20 lb plane with it.

The Saito 220 is running better now, transitions good from all rpms with only a 1 sec slow down, even after extended periods at idle (or any rpm).

The intake insulators did the trick for stabilizing mixture settings at varying engine temps but did not fix the lean cough condition during transitioning.

Here was the major culprit:

This tank is very flimsy. During transition too much of the muffler pressure supply was being used to reinflate the tank instead of applying additional fuel pressure. Swapped it for a rigid 16 oz Dubro tank and things immediately and drastically improved. I was able to lean the mixture from those overly rich ones I was forced to use with the flimsy tank. The engine temps decreased too, as expected.

But all is not well. As the fuel level depletes, leaving more compressible air in the tank, the transition problem (lean coughing) returns, although not as severe as with the flimsy tank. The engine temp rises very quickly when repeatedly transitioned under those lean conditions, as expected, which exacerbates the problem. With 3/4 to a full tank of fuel the transition is rock solid. I was ready to lob the engine into the Taylorcraft, that is until the tank level dropped below 3/4 full and the problem returned.

I'm still convinced that the fuel system needs more pressure, some how, some way and here's why. The engine now never misses a beat transitioning when above 5000 rpm and it doesn't matter if the tank is full or near empty. 5000 is the rpm where the muffler begins providing a higher and exponentially increasing pressure. Below 4000 the pressure curve is flat, essentially not changing much from idle to 4000. To transition these big Saito singles appear to need big fuel and in a hurry.

In the meantime I'll try a smaller tank, a 12 oz. The smaller tank may help, if for no other reason than to prove a theory.

I haven't seen that much from my 220. What prop and rpm? What prop constant in the calculator?

APC 18 x 6, wideblade, 7650 RPM. According to Pé Reivers that was 2,4 hp. Admittedly, that is all peaked to the max and on a lucky day.
I usually tune or 7300~7400 RPM on the ground.
But it unloads to 8200 in level flight, which fo that engine probably is around 2,5 hp

The time delay to build up pressure (or deflate that pressure) is known. But if it affects running, then there is something more going on than only a flexible tank. Most likely a restriction somewhere. Because the volume of gas moving back and forth for that pressurizing is really only small (order of magnitude of about 1/20th of the availlable free volume above the fuel), and that really is nothing. I have so far never heard it to be an issue, and the feedback meanwhile includes a Saito 300 with 16 oz tank in a Pitts Special doing full aerobatics.


Most likely there is a restriction in your pressure line. Can be anything from the nipple on the muffler being coked up a bit, to the diameter of the tubing or the connection on the tank.

But I don't see the need for a 16 oz tank for a 220 engine. 10 oz would allready give you a very decent flight time. I run my 160 with an 8 oz tank, and for normal flying that borders on "ridiculous" with 45 minutes of flight time, and under load, I can do 4 or 5 tows to 600 feet, a bit depending on the weight of the tow with about 25% reserve..

Bert, is your Tygon line sized for a snug fit on 1/8" brass tubing or are you having to use clamps to hold it on?

I'll check the pressure nipple for debris but the tank does seem to vent normally during fueling. The 12 oz tank, lines, felt clunk and fittings are all new and pressure tested.

Snug fit, no clamps. on the plane with the ASP I use 7/64" tubing (At least, I measure about 2,7~2,8 mm), It is a snug but light fit. Has never slipped off in 5 years time, despite not using 1/8 brass tubing but 3 mm.

There really is no need for a tight fit, the pulling-off force acting on a 7/64" tubing acting on the Tygon because of the pressure is only in the order of magnitude of 0,005N or about half a gramme. A bit more than the weight of a hair.
I use a 2 oz craptrap, so even when the tank is full, there is always as a minimum that volume of 2 oz to be pressurized. I regularly fly the tank empty to a 20% reserve margin, and I notice zero difference between full and empty tank. Not even a noticable leaning out in steep climbs. In level flight, the tank is more or less level with the spraybar, in a steep climb (close to vertical) and on a near empty tank the fuel level is about 6" below the spraybar. Never noticed any problems with that in flight.

I really would suggest to simply install that engine in a plane, with a 10 oz Dubro tank and a craptrap of your liking, and start to fly it, to see whether what you think there is on the bench, actually is there in the air.
Don't get me wrong, I do not want to push you, but I get the feeling that you make too much out of the things you see. Sure, you had issues with heat soaking. They have been solved now. Maybe you have an issue with a too restricted pressure line. That can be solved too. Mind you, the occasional connection nipple with 2 mm internal bore is not the big problem. 8" of 2 mm tubing is. Gasses have viscosity too, believe it or not. My pressure line passes a muffler nipple (2 mm bore) a T-connection (2 mm bore. two connections on the craptrap and the connection on the fuel tank. But the tubing (all in all 8" of it) is that 2,77 mm internal diameter, and I do not have any issues with the pressure building up.
My throttle up slowdown is 1 sec, the throttle down slow down is zero. That works perfectly fine. Heck, the slowdown is not even set to 1 sec because of the throttle response... I did that mainly because it makes the thing sound like a much bigger engine. I have tested with 0,6 seconds and that worked perfectly fine too. The "sporty" sound does not fit the sedate aesthetics of that old BigLift... Rapid acceleration is overrated. it is not as important as many think.


Just go fly. You learn more about what works and what not by flying. Testbenches don't fly. It'll really be OK. Just keep your eyes and ears open the first few flights. I had to as well, and it all worked out. As it did with Dave, and many others. It will work out for you as well.

I've never used those water bottle fuel tanks, so I have no experience with the flexible / pumping influence those bottles may have on a exhaust pressurized fuel tank system... Those tanks work well with the pumper / diaphragm carbs, due to the tank being vented to the atmosphere... I never liked the screw on cap, so I always opted for the rigid poly tanks that use the expanded rubber stoppers... I measured the orifice of the pressure fitting in the muffler for the OS boxer and the orifice ID is .078", same as on the saito FA130TD... too small of an orifice will cause a latency in the back and forth exhaust pressure pulse to the tank,

I thought I made it clear that I won't transfer an engine from the bench to a plane until it runs right. That means from a full tank to an empty one, period. If that's "making too much of things" then so be it. Don't worry, I'm not flustered, a bit perturbed with it, yes, but not beaten. Eventually the problem will be found, on the ground.

More likely 2 mm then, as Japan usually uses metric.

Most likely its 2mm... I used a piece of brass tube with a .078" ID on the boxer exhaust... the saito expanded exhaust pipe uses a tube for the exhaust pressure fitting, and a 2mm OD rod is a interference fit... Some of those exhaust threaded pressure fittings are small, less than a 1/16th" ID, as small as 1.3mm... If I can find them, I'll use the threaded fuel nipple from some of the various glow carbs, around 2.3mm ID.

You have now... you'll figure it out with that determination

For the wing span of that rascal, 13 lbs is fairly light... not sure how accurate their spec's are, but even at 14-15 lbs, should be a lot fun with the boxer... nice looking plane too, its considered a trainer, but the most enjoyable flying times are with those types of aircraft... I miss the sig kadet, was a very versatile plane in skilled hands.

Those Rascals are nice, well built. The Kadet Senior ARF is built lighter and flimsier but a very pretty plane. I watched two of those explode into balsa clouds coming out of a loop. Zzzzzzip-bang! Instantly rekitted.

I never flew the Kadet, learned to fly with an LT-40, also a very capable trainer.

Checked the muffler pressure nipple, all clear. Lines too long?

Are you sure you're not getting small air bubbles leaking in where the tubing is connected to the solenoid or even at the tank? I usually double up the tubing at the nipples.

Everything holds pressure solid at 3 psi, no leak down. That's with the carb line plugged and applying pressure through the muffler pressure line.

Bubbles in the fuel line stopped with the installation of the heat isolators.