Rudolph Hart

Yes it does tho you should'nt have to do that unless the single is inverted.Myself and others tune them happily without adding petrol but if for some reason you struggle to get a good low speed throttle response and a nice clean idle then try it it just increases cyl temp a bit.

dasquirrelisme

My Feedback: (81)

I sent you a PM RV7

fiery

My Feedback: (2)

Petrol (gasoline) has been used to make a glow engine run "hotter" forever. Instructions for the early MERCO engines recommend the addition 5% petrol in the mix to assist idle stability in lieu of nitro methane.

chorner

Hey guys, quick question. Trying to decide between the ASP FS400AR and the Saito 325 R5 to power a Top Flite giant P-47. The specs on the ARF say about 21lbs weight on the high side. Will the 325 have enough power? It seems the recommended prop range is about the same from manufacturer specs which doesn't seem right...

whatre your thoughts between the two?

BobH

My Feedback: (2)

Between the two engines the Saito is better.
The 325 will fly the plane if you are under 25lbs. Over that and it will fly but slowly.
Perhaps a better choice is the Saito Fg60. It's perfect for that plane. Unless you don't want to go gas that would be my only choice for a radial.

chorner

Thanks Bob. The only thing that sort of sways me towards the ASP is the fact that 1) it's less than half the price of the 325 and 2) it has a locking "pin" that locks the prop drive to the crankshaft. The reason that appeals to me is I'd be running CDI spark ignition on whatever engine I go with while still preferring to run methanol. If you have a prop strike and all you have is a collet, you could mess up the timing. Does the 325 have any sort of locking mechanism on the crankshaft for the prop hub? By the exploded diagram it doesn't seem like it.

It seems the fg60 is the best fit for the plane for sure. Just don't like running gas nearly as much as it makes quite a mess and chews through things inside the house if you happen to spill it (have a carpeted basement workshop area) and you can't really keep it inside with the smell either.

Radial power

Hello everyone,

today I dusted off (literally ) my OS FR5-300 radial that I had some problems with. It seems that my problems were related to my glow driver setup that had too high of a total resistence, so not enough current went to the plugs and I couldn't keep all 5 cylinders running.
After rebuilding the test stand glow driver system with 6 square millimeters wire and replacing the rocker switch with a homemade electronic switch using 5 mosfets in parallel, I managed to get much more current to the plugs, so I could finally start a proper break-in session. I had to pay attention as the engine wanted to tip my engine bench over when I pinched the fuel line to temporarily lean it out!

But anyway, after completing some runs I brought the engine back in the garage and started messing around with the box of my Top Flite Giant Scale P-47, the plane that I intend to use the OS radial in (who knows when I'll manage to start building it...). I took some measures of the cowl and came to the conclusion that, knowing that the OS 5 cylinder radial is listed as 234mm in diameter, the engine won't fit in the cowl.
Then I went surfing the web and found this post http://www.rcuniverse.com/forum/rc-w...l#post11936734
It shows the ASP-400 not fitting either in a fiberglass specialties cowl, but it is said that by moving the engine (down, I presume?) it should be possible to make it fit without cutting the cowl. This had me wondering: since the ASP-400 (and the Magnum 400 and the PH-400, the same engine under different names) is effectively a clone of the OS radial I have and since the ASP-400 is larger in displacement, then it should also be larger in overall dimensions. So, perhaps, my engine might actually fit in the cowl with only a slight offset
Then I went looking for the size specifications for the ASP-400, but found a figure of 220mm for the diameter. That sounds really strange, as the two engines are very similar in their layout, except that the 400 uses larger cylinders. And yet the OS is listed as having a diameter of 234mm. The OS has a stroke of 22mm (0.866"), while the ASP-400 has a stroke of 23.2mm (0.913"). This should imply that the crankcase of the ASP should not be smaller than that of the OS and that the cylinder height should not be smaller either. So how can that size difference be true?

I went to the garage and started mesuring my engine. I don't have a caliper long enough to measure the width of the engine directly, so I resorted to measuring the distance between the centerline of the engine and the top of the rocker covers for cylinder number 4. This came out as 112mm, which implies a width of 224mm, but as I said my measurement was not that precise and it could be off by a few millimeters. The overall diameter should be somewhat larger, as the #2 and #4 cylinders are not exactly opposite to each other.

So what's the deal? Perhaps the 220mm "diameter" of the ASP-400 is actually its width? So what's its diameter? Can someone with a 400 take some measures of the actual size of the engine? I think it would be useful to know the actual dimensions of an engine should someone decide to buy it. It would be a nasty surprise if one bought an engine thinking that it will fit and then found out that the engine is actually larger...

Andrea.

SJN

Hi Andrea, I just meassured mine.

The radius on mine is 11.5cm....so 23cm diameter.

Radial power

Thank you SJN,

so it seems like the ASP and the OS are the same size or very close to that.
As I said I measured the width of mine and came up with 224mm, give or take a few mm. This seems consistent with the published size of the ASP of 220mm, while your measured diameter of 230mm is very close to the listed diameter for the OS (234mm). So i'd say that the overall sizes are indeed very close if not exactly identical.

Good job for Magnum, ASP or whoever originally designed that engine with more displacement yet the same overall size as the OS.

Andrea.

SJN

yea, but it does not change te fact that the metal used in this engine is of low quality, and will not last long.

get the saito fg 60, and have many succesfull flights :-)

BobH

My Feedback: (2)

I would agree. The Saito will last and last being pretty much trouble free for a long time.
There IS a reason for the price difference!

Radial power

Ehm, perhaps it got lost in my long post, but I do not have an ASP-400 (or equivalent) engine. I have the "original" OS FR5-300. I'd hope that the metal it's made of is of sufficient quality...
I asked about the ASP as a comparison: not many people use the OS radial, so it's difficult to find real-world use cases for it. The ASP is much more common. Knowing that they are the same size allows one to know that if one of these engnes fits in a particular installation, then the other fits too. That's it.

Andrea.

chorner

I think for the OS or ASP radial you're looking at cutting the cowl for at least one of the rocker covers. The FG60 is a perfect fit, but for me I prefer not to run gas

Radial power

We'll see. The stock cowl of the Top Flite Jug seems way to small, but a quick search indicates that the fullsize R-2800 engine of the Thunderbolt is 1342mm in diameter. The wingspan of the kit (85") when compared with the wingspan of the fullsize plane (40ft 9in) indicates a true scale of 1:5.75 which, when applied to the size of the engine, gives a scale diameter of 233mm, just shy of the 234mm diameter of the OS radial. Then obviously the P&W R-2800 may be sitting further back in the cowl than it will be possible with the OS radial, but perhaps with a slightly modified cowl and/or a prop extension it might be possible to make everything fit.
It will be a "oil the rocker covers and slide the cowl on" thing though

Anyway, I ran the engine again this morning. Throttle response is nothing short of spectacular: I couldn't get the engine to miss a beat in acceleration no matter what I tried. When trying a sudden deceleration it would sometimes pop from one or more cylinders. That makes me suspect that I may be slightly too lean on the low end, as my Saito FA-90TS pops like that when the low end is set lean. That would make the sudden acceleration even more impressive, as normally a lean idle results in the engine cutting out in acceleration.
I saw a peak of 6400rpm on a Menz S 20x10. That was in a very hot (over 30°C) and humid morning, with homebrew fuel containing 10% nitro, 15% Motul micro synthetic oil, 3% castor and the rest methanol. My guess is that it may gain a few hundred rpm more with a few more liters of fuel through it (and perhaps a new set of glow plugs...). I didn't keep track of the exact numbers, but I'd say that the engine used slightly less than half a liter of fuel for shightly less than half an hour of run time with varying throttle settings. Take these numbers with a grain of salt though.
Got a (nearly) steady idle at 1100rpm with glow heat despite my crude throttle setup on the test stand, but I still need to tweak the low end to get a really good idle. It was also acting somewhat strange: while idling at 1100rpm it would hold this speed for some time, then suddently accelerate by a few hundred rpm for like 5 to 10 seconds, and then drop back down again to 1100rpm. Rinse and repeat. My guess is, again, that I may be a little too lean on the idle setting and some cylinders may be dropping out and coming back online periodically. Another reason I suspect the low end is lean is that there seems to be a slight delay between the time I close the throttle and when the engine actually goes to idle.

I tried to run the engine with the breather nipple plugged to see if that could force some more oil to the rocker covers. After the first run I opened the rockers of the top cylinders but found exactly what oil I had put in when I checked the valve lash a few days ago. On the second run the engine blew off the silicone tubing that I had used to plug the nipple, so I decided to continue the run with the nipple open. I'll keep an eye on the oil level in the upper rocker boxes, but It seems I'll have to oil the top rocker boxes periodically. Not a big deal but still something to remember.

Given the current weather here in northern Italy I can only run the engine in the morning (lest I melt ). That basically reduces to saturday morning, as the other days I'm either at work or at the flying field. We'll see if I can get some more run time on the engine next week.

Andrea.

jymster

My Feedback: (9)

Andrea,

Indeed the cowl on the TF P-47 is too small. It is much too narrow at the front. I am getting ready to start my TF P-47 and have to either find a more accurate cowl (anyone know of one?), or modify the stock one from Fiberglass Specialties, or make a new one myself. I have a feeling that I may be doing the latter.

Also, with regard to your O.S. radial, have you ever thought about reducing the oil content to allow the engine to really perform? Radials do not need as much oil as their single cylinder brothers. For my Evolution 77cc radial, I run it with 7% oil, and it performs flawlessly. I have around 80 flights on it now, and it is still going strong. I am bewildered to know why O.S. still recommends such a high oil content in their radials, it would surely be slowing the engine down a lot.

Heli-NuBee

Please do not run 7% oil in an OS radial engine. Use regular glow fuel with at least 17 % oil. The OS engine oils the crank and rods by blowby from the upper cylinders. Fuel flows directly to the cylinders and does not pass through the crankcase. The UMS Evolution radials take fuel through the crankcase and have a much more active oiling of the rods and crank bearings by that process. That is why the UMS radials can run a much lower percentage of oil. Fuel induction and oiling is different between the OS and UMS radial engines.

Best wishes and good safe flying.

Heli-NuBee (AKA Roger the radial rabbit)

jymster

My Feedback: (9)

Thanks for the advice Heli-NuBee, I was not aware that there was such a difference. I was curious, and so had a look at the exploded view of the O.S. FR5-300. It looks to me that the fuel enters the rear of the crank case from the carby, just as it does in the Evolution/UMS radials. Am I missing something? I am not trying to be smart, I am truly interested in the difference between how the two engines operate. Thanks.

SJN

Number 49 is not open to the crank case......the "hole" you see in the picture is actualy a blanked off wall deviding the crack case to the intake manifold.

jymster

My Feedback: (9)

Thanks Sonnich, it makes perfect sense now.

Heli-NuBee

OK, I guess the question has been answered. The OS 300 does not lubricate the crankcase through the intake, it lubricates through blowby from the cylinders. The instruction book (http://www.os-engines.co.jp/english/...al/fr5-300.pdf) clearly says to use at least 18% oil and 5 to 20% nitro. The new OS 420 radial is similar to the UMS engines and can use much lower oil content. The ASP 400 radial (OS copy) is the same as the OS 300 and must use 18% or greater oil content. I hope that this helps.

Best wishes and good safe flying.

Heli-NuBee (AKA Roger the radial rabbit)

Radial power

Yeah, as far as I can tell the fullsize cowl keeps a more or less constant width from the back up to a point not far behind the front lip of the cowl itself. Only in the very last part does it start to converge. The TF cowl, on the other hand, starts converging right at the firewall, and this quickly reduces the available room.
I'm with you with the idea of getting a different cowl. My plan is to get the Fiberglass specialties cowl and then modify it as needed. Or perhaps create a new cowl from scratch and reuse some parts of the Fiberglass specialties cowl. I'll see when I get there.
I was also wondering whether it may be feasible to have a cowl that is split in three pieces lengthwise, with the bottom piece fixed in place and the two top pieces hinged at the bottom. In this way it may be possible to easily access the rear of the engine and the top rocker boxes for inspection and oiling (the bottom ones shouldn't need oiling as far as I have seen). All of this without having to remove the prop. And it may even be useful to show off the engine at the field

I'll also get an exhaust ring for the engine. I already have a Keleo exhaust on my Saito FA-90TS and it is very good, so a Keleo ring will certainly be used. I'll try and ask Kelvin whether it may be possible to build the ring using a bigger tube diameter for the ring itself to try and get an even deeper sound than the standard ring (trying to mimic the Moki radial ring there, with its very "fat" ring).

I'm not going to run less than 18% oil in the my OS radial, don't worry. However I'm curious as to how the FR7-420 manages to get away with only 10% oil. According to the exploded diagrams its induction path is very similar to that of the older FR5-300 (except for the impeller). How come the FR5-300 needs 18%, while the FR7-420 can get away with 10%? Better materials?

Andrea.

chorner

I emailed fiberglass specialties about their cowl, and he merely stated theirs is a copy of the kit cowl and not the ARF cowl. Does anyone know the differences between the KIT and the ARF cowl? Does the kit cowl provide a bit more room in the nose of the cowl, and would it fit properly on the ARF?

jymster

My Feedback: (9)

Chorner,

Yes, indeed the Fiberglass Specialties cowl is just moulded off the standard kit cowl, as are pretty much all of their cowls for other kits too. The kit cowl is completely wrong also, very narrow at the front and so no better than the ARF cowl by the sound of it. I had actually hoped that the ARF cowl could be better than the kit cowl, but you have answered my question about that. I think I will have to make my own.

chorner

Jymster, and you have answered my question as well then. Damn, I was hoping there was an easy solution available for a slightly larger cowl. The ARF cowl is certainly no better then, but interestingly enough there are two videos on YouTube up of a TopFlite P47 running an ASP FS400ar. The ARF seems to only have on rocker cover protruding while the kit version as multiple - not sure of any potential installation differences though

Radial power

Hello everyone,

I'm still in the process of tuning my FR5-300 on the bench. I can only do a run every week (due to the weather), so it's taking quite some time.
I thought the idle was too lean, but now I suspect it may be still too rich. Also I think that the MenzS 20x10 may be slightly too much prop, at least until the engine has some more run time on it. So I'll try to get a 20x8 to up the revs a little bit. There's also a slight problems with the OS wiring harness, which is getting loose and causing some plugs not to receive a continuous flow of current when glow heating is on. I'll have to remedy that as well.

Meanwhile there's a newcomer alongside the FR5-300 radial:


I know, I know, it's not a radial. But perhaps we can consider it as a form of 4-row 1-cylinder-per-row radial?
At least it's still aircooled...

I've had that purchase on my radar for quite some time, but as the P-47 for the FR5-300 is the next plane in the to do list (you can see the box in the first photo), the plan was to purchase that engine as the P-47 was nearing completion. However, I noticed that Tower now lists this engine as discontinued http://www3.towerhobbies.com/cgi-bin...&I=LXPRL5&P=PU . I asked both my LHS owner and another hobby shop whether the engine is really discontinued by OS, but they gave me different answers: the LHS said that the engine is still available, while the other shop basically said "you're right, there's only one left in the importer's warehouse. Hurry up!". The second shop's answer sounds a lot like they're just trying to get a sale, but the fact that Tower lists it as discontinued is not a good sign. So I ordered it anyway (from the LHS). One less cylinder than the FR5-300 for nearly 1000€ more. Sounds like a good deal

The initial idea was to use the Il-300 in a P-51, but then I realized that such a choice is just too obvious. A less common alternative would be a Bf-109K, but then I found the perfect plane: https://en.wikipedia.org/wiki/Reggiane_Re.2005 . Very clean and beautiful lines, almost no one has it, smallish fullsize wingspan so that it can be built at a farly large scale without the plane getting to big and/or heavy while at the same time offering a reasonable amount of space in the nose for the engine. And it was built here in my town (the old factory still exists, even though it's abandoned now)!
I'll have to figure out how to mount the engine fully enclosed, drawing in cooling air from the radiator scoop under the belly. And also I'll have to somehow get a rather long prop extension, which will have to be supported at the front end.

But there's always plan B:


The Il-300 alone weighs more than the plane with the little wankel... Plus I MIGHT have some c.g. and prop clearance problems. Anyone got a 10 blade prop?

Andrea.