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Everything Radial Engines

Old 02-23-2021, 06:43 PM
  #3851  
N99JH
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Update:

Slow progress but progress nevertheless. I finally spent 2 days in my shop and machined the spacer. Here it is mounted on the Fa-80 test engine. Next step is to machine a new longer connecting rod, and if no problem encountered, the last step will be new push rods, new push rod tubes and extending the intake tube.




Old 04-19-2021, 01:34 AM
  #3852  
RoKit
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Hi everyone !

I am new on this forum, I came across a new (2008ym) Saito FA170R3 and get a bit worried when reading posts about 3R Saito.
I have ordered CDI ignition from Morris mini motors and intend to run the engine on methanol.
Morris mini motors also have a intake manifold mod but it´s very expensive.

Now I wounder... how worried should I be about the engines durability ?
Is it possible to make changes to the original intake manifold ?






Old 04-21-2021, 01:37 AM
  #3853  
Linkan2
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hey RoKit I have a 170 3R is about 20 years old and it works very well. I have a glow on board. Do not think you need to buy new intake the first things you do. Lars
Old 04-21-2021, 04:54 AM
  #3854  
RoKit
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Originally Posted by Linkan2 View Post
hey RoKit I have a 170 3R is about 20 years old and it works very well. I have a glow on board. Do not think you need to buy new intake the first things you do. Lars
Thanks / Tack..

I will run it with the Ignition and suppose that time will tell.
Have no experience from radial engines and got worried when reading that there is temp issues
due to fuel distribution. //Rob
Old 09-12-2021, 06:15 PM
  #3855  
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Hey guys, sorry radial noob here. Are there any issues with mounting a gas UMS 7-90 radial 90 degrees sideways?
Old 09-13-2021, 03:59 AM
  #3856  
Maxam
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No, should not be issues sideways. Does that a lot in the air! The top cylinder is still the top so install the spark cables as if it is still mounted conventionally. -Tom
Old 09-28-2021, 06:08 AM
  #3857  
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Hey allI have a question/ problem with my Saito 325 R5. Wondering if anyone would like to chime in on this specific radial who has experience with them.
thanksAaron-
Old 11-25-2021, 03:19 PM
  #3858  
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Hi Guys,
Im resurrecting the build of my Flair Stearman which has been resting in the attic for 'a few' years now but nearly complete. I am toying with the idea of powering it with a UMS 90cc 7 cylinder radial (would have loved a robart radial when they were available!). As the aircraft should fly happily on a single cylinder Saito 180 (which I have already), Im concerned that I might be putting too much power and weight up front for the sake of mounting a scale diameter (9.75 inches) radial.

Any thoughts and advice gratefully received.

Harriermate
Old 11-25-2021, 03:28 PM
  #3859  
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Oops . near repeat message as thought first hadn't posted!!

Last edited by harriermate; 11-25-2021 at 03:38 PM. Reason: Repeat message
Old 11-25-2021, 03:31 PM
  #3860  
RichardGee
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Originally Posted by harriermate View Post
Hi Guys,
Im resurrecting the build of my Flair Stearman which has been resting in the attic for 'a few' years now but nearly complete. I am toying with the idea of powering it with a UMS 90cc 7 cylinder radial (would have loved a robart radial when they were available!). As the aircraft should fly happily on a single cylinder Saito 180 (which I have already), Im concerned that I might be putting too much power and weight up front for the sake of mounting a scale diameter (9.75 inches) radial.

Any thoughts and advice gratefully received.

Harriermate
As anyone who has dreamed and schemed about putting a "scale" radial on the nose of his RC project has learned, our model radials do not have a linear relationship with their full scale counterparts in regards to size and weight.
While you may find a way to balance your Stearman with the 6.1 pound UMS 90cc radial on the nose, you may also find that flight performance suffers from this grossly imbalanced situation.
My suggestion? Go for the 50cc 7 cylinder. Yes, it is smaller and does not present as a SCALE sized radial, but the power and weight will be ideal and the WOW factor will still be there.
I am guessing with the 90cc 7, IF you could get it to balance, you would rarely go beyond 1/3 throttle.
The 50cc 7 would provide a very good margin of power, but wouldn't create MAJOR balance problems, like the 90cc.
My $0.02
Old 11-25-2021, 03:42 PM
  #3861  
harriermate
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I think Cybertom had a 160cc Robart 7 cylinder strapped to the front of his Flair Stearman... but not sure whether it balanced easily. The aircraft has a relatively short nose so might need nose weight anyway. Best i hang a few weights to the front to see what the likely ballast requirement might be.
Old 11-25-2021, 04:21 PM
  #3862  
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Originally Posted by harriermate View Post
Hi Guys,
Im resurrecting the build of my Flair Stearman which has been resting in the attic for 'a few' years now but nearly complete. I am toying with the idea of powering it with a UMS 90cc 7 cylinder radial (would have loved a robart radial when they were available!). As the aircraft should fly happily on a single cylinder Saito 180 (which I have already), Im concerned that I might be putting too much power and weight up front for the sake of mounting a scale diameter (9.75 inches) radial.

Any thoughts and advice gratefully received.

Harriermate
Guy here put the glow 7-77 on one. Seemed to work good for him at half throttle. The gas 90 might be doable?
I put a ASP400-R5 (65cc) on a Maxford 1/5 77” Stearman with good results. Just moved servos to the rear and braced landing gear for the extra weight.
There is a tipping point where weight and power do become excessive though…
​​​
Flair 1/4 Scale PT-17 Stearman Review

Last edited by darkith; 11-25-2021 at 04:30 PM.
Old 11-25-2021, 05:21 PM
  #3863  
redball8
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I had a Flair Stearman and was planning to put an Evo 999 (9 cylinder 99cc) in it. It could work, but the 777 is probably a better match for a 90” span biplane.
Old 11-25-2021, 09:36 PM
  #3864  
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Overpowered biplanes are not very nice to fly..despite the engine looking scale. You end up with high engine torque.
Old 11-26-2021, 06:35 AM
  #3865  
Hinckley Bill
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Here's some videos of Flair Stearman's with radial motors installed:
Old 11-27-2021, 02:40 PM
  #3866  
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Ok…. I’m convinced! I need a 7 cylinder radial and the UMS EVO 7-77 is available in U.K.! So now to my next question…. Having never had a radial before, what are the pros and cons of glow versus petrol (gas). Will a glow radial engine run without permanent electric power to the plugs as per single cylinder???? Which is more frugal on fuel and which is the easiest to set up?????
sorry for all the questions… but there seems to be lots of expertise here!
thanks in anticipation!
Old 11-27-2021, 03:06 PM
  #3867  
N99JH
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There are really no pros to glow radials. The nitro fuel is more expensive, the finish needs to be fuel proof, you need to clean the mess at the end of every flying day, and - it still is recommended to have plugs heat to keep all cylinders firing.

Petrol with electronic ignition is customary these days and is the way to go in my humble opinion. You can have a petrol radial with spark instead of glow plugs and the ignition is very reliable. I don't think that UMS even offer their radials with glow plugs.
Old 11-27-2021, 03:22 PM
  #3868  
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Doesn't Saito sell a five-cylinder 70cc gas radial? The FG-73R5? Not sure if any Stearman had a five-cylinder engine, though.

Me, I love my glow radials, but can get methanol cheap (pump methanol is ~$3/gal). For me it isn't the cost but the safety - methanol is a lot less volatile than gasoline, hence its use in auto racing. I do use onboard glow (no heavier than ignition system), but Maxam swears they don't need it, Glow is a tad more powerful than gas, but you need more of it - about four times more! Glow really only makes sense for 30cc on down, the big radials are something of an exception. I have a 990 on a giant Telemaster and it's really cool on landing with full flaps, plus a 770 on a Gee Bee Y that flies like a warbird. I can certainly understand that gas is a lot easier for most folks.

Last edited by redball8; 11-27-2021 at 03:34 PM.
Old 11-27-2021, 03:48 PM
  #3869  
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All Stearmans were powered by 7 cylinder radials, mostly Continentals and Shaky Jakes.
Old 11-27-2021, 04:08 PM
  #3870  
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Glow four strokes (including radials) are also more prone to rust issues due to the hygroscopic nature of methanol and nitromethane. You have to diligently run them dry and may need to treat heavily with after run oil (seems to depend on the quality of steels used and the humidity or the storage environment)

Gas radials don’t suffer from this problem and will generally stay rust free from just the oil present after use.
Old 11-27-2021, 10:57 PM
  #3871  
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Go with gas

Ive had the UMS 7-77 for 10 years. More maintenance and I mix my own glow fuel for it.

Also, I had to add a Sonic Tronics glow control to it so as to keep the bottom cylinders lit. This, and associated battery, is approximately the same weight as an ignition unit and battery.

5 cylinder only. Once you fly a radial....you’ll be hooked
https://www.morrisminimotors.com/ums...e-ums5-75.html

Last edited by cymaz; 11-27-2021 at 11:04 PM.
Old 11-27-2021, 11:46 PM
  #3872  
harriermate
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Guys,
Thanks for all the extremely useful advice. I just need to order one now! 😇
Old 11-28-2021, 06:08 AM
  #3873  
RichardGee
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Red face Radials, glow vs. gas

Originally Posted by harriermate View Post
Guys,
Thanks for all the extremely useful advice. I just need to order one now! 😇
I own many glow and gas radials and have flown several. One of my favorites was my Technopower 9 cylinder. It was meticulously broken in and run with a McDaniels (Sonic Tronics) 9 cylinder glow driver.
The beauty of on-board glow is that I could start the engine with nothing attached to the airplane; just switch on glow and fire it up.
With glow on, the engine would idle down to 900 rpm.
Without glow, it would idle reliably at 1200 rpm.
In the event the engine would drop a cylinder in flight - which could be heard by the drop in rpm - a flip of the GLOW ON switch would have it running again... although the Techno was very impressive in this regard, as that was rarely needed.
I had similar results with a UMS 9-90, 9 cylinder glow, also a VERY nice running engine.
I have also run the Seidel 5-40, Magnum 5 cylinder, and O.S. Sirus 5 cylinder, all glow.
All are mechanical marvels and a joy to run and fly.
That said, I MUCH PREFER my gas radials for all the reasons already stated.
Now, I COLLECT glow radials and RUN gas radials. IF given a choice in radials to go out and fly, GAS wins hands down.
Old 11-28-2021, 06:48 AM
  #3874  
Maxam
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Poor glow radials!! You guys are soo mean! I am still regularly flying a Saito 90r3, UMS 7-70, 7-77 and 9-90. Oh yes I love my Moki 215's and 257...I tried a new UMS 5-75. It ran very hot, had lean spots at mid throttle and gunked up so much the valve seats lost compression. I believe the Amsoil oil was partly at fault. I have since bought a UMS 55 cc 5 cylinder engine. Beautiful engine with great proportions. I used Redline oil this time. Super easy to start but the UMS carb is not good. Way too large choke area, so I adjusted full throttle to be half open which improved things to a more satisfactory level but still overly rich off idle. Well, I just had to do it.....got a Saito 90r3 carb, made an adapter for the 5-55 and holy Toledo!!! Now it is one of the best running radials ever!! (with a valley girl accent) Super easy to start, correct fuel delivery at all throttle settings and it is a torque meister swinging a 22x10 Xoar prop at 4600 rpm, 1000 rpm reliable idle. After break in 40:1 92 octane ethanol free gas/ Redline oil and 2oz Sea foam/ gallon. Engine does run hot at 220F. 4oz fuel for a ten minute run; fly for almost free! True horsepower calculated from the Astro Flight equation 1.8 Hp. That is actually quite good.
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Old 11-28-2021, 08:29 AM
  #3875  
Hinckley Bill
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Happened across this video and thought I'd share it with all those who love that 'radial sound'...

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