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Everything Radial Engines

Old 07-22-2010, 07:28 AM
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Default RE: Everything Radial Engines


It looks like the exhaust stubs are retained by a flange on the tube, similar to the Saito and others, in which case you can swivel them around and point them in any direction.

The WWI rotary engines didn't just vent their exhaust inside the cowl. Because the whole engine is spinning, each cylinder, in firing order sequence, exhausts at the same point i.e. when the particular cylinder is pointing vertically down. Many WWI planes had a horseshoe cowl, I assume to allow for the duration of exhaust valve opening. They were very messy engines, with total loss oil systems using castor oil... A static RADIAL engine in a WWI plane really should have a collector ring with the exhaust pipe pointing down, out through the bottom of the cowl. Glow engines are just as messy!

Regards, RossG
radial1951


ORIGINAL: abufletcher

So what's the difference between the ST-710 and the ST-770? Is the later just an update of the now out-of-production ST-710. If so, why the different designation?

Also, in this photo, the exhaust tubes are facing forward compared with other photos of the ST770. What's up with that? Are they movable? I assume that the exhaust can just be vented into the air (with a WWI style cowl) as on the original rotary engines.
Old 07-22-2010, 07:43 AM
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Default RE: Everything Radial Engines

ORIGINAL: radial1951
A static RADIAL engine in a WWI plane really should have a collector ring with the exhaust pipe pointing down, out through the bottom of the cowl.
What sort of collector rings have people been using on their Seidel engines?
Old 07-22-2010, 08:37 AM
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Default RE: Everything Radial Engines

Keleo Creations doesn't do a collector ring for the Seidel (yet). Here are two owner built exhaust systems, pretty sure by members of this forum. One appears to be all silver soldered, the other used silicon to seal the individual pipes into a ring. Not sure if that was successful. Both appear to have used commercial Stainless Steel (?) elbows to fabricate the ring.

Regards, RossG
radial1951


ORIGINAL: abufletcher

ORIGINAL: radial1951
A static RADIAL engine in a WWI plane really should have a collector ring with the exhaust pipe pointing down, out through the bottom of the cowl.
What sort of collector rings have people been using on their Seidel engines?
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Old 07-22-2010, 09:53 AM
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Default RE: Everything Radial Engines

Hi Seidel people, I now have 10 16 oz tankfuls through my 9-90. Using a thickish 24x12 (meaning higher load than a xoar) the engine is reaching a solid 5500 rpm! That is quite reasonable power. My 7-70 was turning a 22X12 at about 5200 rpm. On large props a small rpm difference can mean much power differences. The 9-90 is becoming more reliable, not loosing a cylinder without glow power. i am now down to 8% oil.
Old 07-22-2010, 11:26 AM
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Default RE: Everything Radial Engines

Keleo does make exhaust rings for the Sedeils but you have to send them your engine so they can custom fit.Keleo told me when I inquired that Sedail engines vary enough so they can not offer a standard pre built exhaust system.
Old 07-22-2010, 01:42 PM
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Default RE: Everything Radial Engines

As I recall Kelvin at Keleo had fitment issues with the Seidels, so he wasn't going to make them anymoresomething to do with the angle of the exhaust ports going into the heads. Then again, his stance might have changed later on.

Seidel was making their own rings for a while too. My 996 came with the ring already fitted. Seidel solved their own issue with fitment by creating stacks with threading on both ends... you would screw it into the head, then onto the primary ring. It might be worth emailing them to see if they are still available.

Attached are two photos. One is my 770 with two custom rings... both made by Keley (sorry, both were sold off, so none are available). The other shows (badly) how the stock ring is attached on my 996....
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Old 07-22-2010, 02:55 PM
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Default RE: Everything Radial Engines

http://www.sonnenhof-modellbau.ch/ sells 7 and 9 cyl exhaust rings for the seidel radials. Front mounted with all the fittings and new shorter length exhaust pipes to fit the ring. Expensive price tag and you must pay by bank transfer of funds to their account. The ring is untreated steel and front mounted. They are nice to deal with and have Seidel parts available. Doc
Old 07-22-2010, 03:00 PM
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Default RE: Everything Radial Engines

http://www.sonnenhof-modellbau.ch/Ve...ngsmotoren.htm Google will translate to english for you.
Old 07-22-2010, 06:14 PM
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Default RE: Everything Radial Engines

O.S did it, finaly



this is the new O.S. FR7-420 7-Cylinder Sirius


PRICE AT 3499$ [:@]

(you can buy seidel ST7-70 for 1199$ at hobbyking
http://www.hobbyking.com/hobbyking/s..._Radial_Engine

or the Seidel 9 cylinders ST9-90 for 1499$




back to O.S. FR7-420 7-Cylinder Sirius
this info from towerhobbies

FEATURES:
V-shaped individual valve covers for vintage scale appearance
Impeller system distributes air-fuel mixture equally to each cylinder
ensuring high performance and smooth idle

INCLUDES: O.S. FR7-420 7-Cylinder Sirius 4-Stroke Engine

REQUIRES: Fuel: Aircraft blend 5-10% nitro content with 8-10% lubricant
content
Propeller: 22x10-12, 23x8-12, 24x8-12, 26x8

SPECS: Displacement: 0.6071cu in x 7 (9.95cc x 7) Bore: 0.944" (24.0mm)
Stroke: 0.866" (22.0mm)
Practical RPM: 1,500 - 7,000
Weight: 111.7 oz (3.167g)
Distance from Backplate to Drive Washer: 6.2" (158.5mm)

when we will see gas engines from O.S ?
when we will see 9 cylinders radial?
Old 07-22-2010, 06:25 PM
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Default RE: Everything Radial Engines


ORIGINAL: Maxam

Hi Seidel people, I now have 10 16 oz tankfuls through my 9-90. Using a thickish 24x12 (meaning higher load than a xoar) the engine is reaching a solid 5500 rpm! That is quite reasonable power. My 7-70 was turning a 22X12 at about 5200 rpm. On large props a small rpm difference can mean much power differences. The 9-90 is becoming more reliable, not loosing a cylinder without glow power. i am now down to 8% oil.
Congrats bud....would like to see that baby in action!

I wont be running mine anytime soon, too busy right now. I just wanted to get it aquired while they were there.



What sort of collector rings have people been using on their Seidel engines?
I intend to build my own ala KMOT
Old 07-22-2010, 07:47 PM
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Default RE: Everything Radial Engines

Hello
How many months have you waited to get your engine?
and which site - store did you bought it from?
Old 07-22-2010, 07:58 PM
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Default RE: Everything Radial Engines


ORIGINAL: Dad_Roman


I intend to build my own ala KMOT
It can be done!
Old 07-22-2010, 08:04 PM
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Default RE: Everything Radial Engines


ORIGINAL: Kmot

It can be done!
Dont worry my friend....Ill be in touch
Old 07-22-2010, 08:06 PM
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Default RE: Everything Radial Engines

ORIGINAL: flashback

Hello
How many months have you waited to get your engine?
and which site - store did you bought it from?
Seriously....welcome to the thread....but you should read some of it first.

Most recent purchases have been of the engines you just posted....from the store you just posted them at.

Wait till its in stock....order....one week later you will have it in your hands.
Old 07-22-2010, 11:31 PM
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Default RE: Everything Radial Engines

ORIGINAL: MarvinE255

http://www.sonnenhof-modellbau.ch/ sells 7 and 9 cyl exhaust rings for the seidel radials. Front mounted with all the fittings and new shorter length exhaust pipes to fit the ring. Expensive price tag and you must pay by bank transfer of funds to their account. The ring is untreated steel and front mounted. They are nice to deal with and have Seidel parts available. Doc
"Ringschalldämpfer hinten"

This to me means that the ring is mounted BEHIND the engine. I certainly wouldn't want a collector ring in the front, which would spoil the whole visual effect. Incidentally, why couldn't the exhaust just be allowed to vent out "all over the place" within the round cowl of a WWI type model? My understanding is that the primary purpose of rounds cowls over rotary engines was to keep them from spewing oil everywhere. Would there actually be a problem running the engine (in a model) without a collector ring?

Obviously doing this in a more closed-cowl type later aircraft would be a problem. But it seems like the typical "open face" cowls (with vent areas below) would easily allow the exhaust to flow down-and-out through the bottom rear of the cowl. So again, why would we need a collector ring on such a model?
Old 07-22-2010, 11:40 PM
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Default RE: Everything Radial Engines

BTW, it bothers me that so many websites are still showing photos of the PREVIOUS production model of the Seidel with the black cylinders since that's NOT what's for sale anymore! In fact, you also don't get the nice little metal plaque on the crankcase or even just red-letter markings. I guess I don't really care, but I'd like to see photos of what I'm actually going to receive not of some "last year's" version.

I assume, that for the following video, even though it was just posted, this is actually an older version of the engine (black cylinders and exhaust tubes):

http://www.youtube.com/watch?v=Swopc...eature=related

This video shows the "new" model with the all "silver" cylinders and the simple engraving on the crankcase:

http://www.youtube.com/watch?v=zgbnj...eature=related
Old 07-22-2010, 11:56 PM
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Default RE: Everything Radial Engines

ORIGINAL: Maxam
My 7-70 was turning a 22X12 at about 5200 rpm.
What size or weight model would this be suitable for? I'm getting the sense that the 7-70 would be about like a Zenoah G-62...or would it be more like the G-38 (or about a 150-180 4-stroke)? In this sense the 770 would seem to be a LOT of engine for a 1/4 scale model of one of the WWI single-seat fighters, but ok for a 1/4 scale two-seater or even a 1/3 scale fighter.

I'd really like to put the 770 in a 1/4 scale Pup (77" wingspan) just to get started in larger scales but would this be ridiculous?
Old 07-23-2010, 01:02 AM
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Default RE: Everything Radial Engines

Sorry if I caused any confusion. I posted the two photos to demonstrate what the muffler options have been historically. Rest assured that if you buy a UMS engine fro HK, thenit will be all silver with no name plate.

I'm not sure if you can get the original Seidel styling anymore. Perhaps ums can custom build one for you, if you prefer.

So far, we know that HK is cheap and will delivery reliably,so long as their stock numbers are positive.

i suppose that the best option for scale WWI building would be to get a Replica Engines 1/4 scale gnome monosoupape rotary engine and watch all of those jugs spinn just like in the old movies.... That would be absolutely stellar! Www.replicaengines.com

Most WWI rotaries had a single pushrods and rocker per jug (with notable exceptions like the bentley BR2 and clerget). The gnome, obuseral, and LeRhone each had one rod only.
Old 07-23-2010, 05:57 AM
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Default RE: Everything Radial Engines

ORIGINAL: stevesak
Sorry if I caused any confusion. I posted the two photos to demonstrate what the muffler options have been historically. Rest assured that if you buy a UMS engine fro HK, thenit will be all silver with no name plate.
Thanks for posting those photos. I wasn't referring to them but rather to the photos still up on many websites for example the sonnenhof-modellbau site still shows the older version (as does the Seidel site I think). I don't mind the new all silver one...in fact in some ways it looks more like the original engines. I do miss the 6-bolt prop hubs though.

So far, we know that HK is cheap and will delivery reliably,so long as their stock numbers are positive.
I've been in direct email contact with one of the managers at the UMS plant and they have been very prompt and professional so far. I was sent an invoice for 910 Euro including shipping to Japan. Now I just have to make a final decision.

suppose that the best option for scale WWI building would be to get a Replica Engines 1/4 scale gnome monosoupape rotary engine and watch all of those jugs spinn just like in the old movies.... That would be absolutely stellar!
Maybe, but flying a rotary engined model with all that wacky torque is not or the faint-hearted. As many Camel pilots were killed in take-off and landing accidents as were killed in combat.

Most WWI rotaries had a single pushrods and rocker per jug (with notable exceptions like the bentley BR2 and clerget). The gnome, obuseral, and LeRhone each had one rod only.
I've always been a stickler for scale fidelity and I certainly wouldn't accept a dummy Clerget in place of a dummy Oberursal. But the Seidel, despite it's scale shortcomings has so much impact that I think I'd prefer that even over an outstandingly scale dummy engine. That fact that it's a REAL engine means a lot to me. And the fact that it's 2.6 kilos of REAL ENGINE really helps on these short-nosed models. I'll also add that I wouldn't even think of using any of the other available radials in a WWI scale model. Wonderful as a Moki, Robart, Saito, or OS might be, none would look right in a WWI model. And what's the point of having such a great engine if you have to cover it up with a better looking dummy?

So...can I fly with the Seidel WITHOUT a collector ring?
Old 07-23-2010, 06:13 AM
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Default RE: Everything Radial Engines

Here's a nice contrast in terms of scale realism between a Seidel in a 1/4 scale EIII and a modified Williams Brother's LeRhone kit on my 1/6 scale EIII. The dummy is absolutely more scale in appearance. But there's something very "scale" about having an actual round engine (and no ugly muffler) as well as a "scale sound" (though even that is a bit of a fantasy).
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Old 07-23-2010, 06:16 AM
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Default RE: Everything Radial Engines

It's the same problem as with the OS IL-300 inline. The few people who have one like to stick them in models like the Albatros but in terms of scale appearance, they are really all wrong.
Old 07-23-2010, 06:26 AM
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Default RE: Everything Radial Engines

Thank you Dad_roman.
Old 07-23-2010, 06:33 AM
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Default RE: Everything Radial Engines

ORIGINAL: abufletcher

ORIGINAL: Maxam
My 7-70 was turning a 22X12 at about 5200 rpm.
What size or weight model would this be suitable for? I'm getting the sense that the 7-70 would be about like a Zenoah G-62...or would it be more like the G-38 (or about a 150-180 4-stroke)? In this sense the 770 would seem to be a LOT of engine for a 1/4 scale model of one of the WWI single-seat fighters, but ok for a 1/4 scale two-seater or even a 1/3 scale fighter.

I'd really like to put the 770 in a 1/4 scale Pup (77'' wingspan) just to get started in larger scales but would this be ridiculous?
ST770 =4HP
power as 40cc gas engine or like OS FT-300
that stronger than SAITO 180 = 2.8 HP
Old 07-23-2010, 08:32 PM
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Default RE: Everything Radial Engines

BTW, in the photo of the 1/4 scale EIII I posted above, it looks like there's no collector ring...which is good news for me.
Old 07-23-2010, 10:59 PM
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Default RE: Everything Radial Engines

Ok... Here's a thought. I'd bet that those stacks are positioned as such, on the new Seidel engines to cause blow-by to pass over the heads and keep the rockers nice and lubricated.... Similar to some two stroke radials, like the G-Mark and triscamp which diectly cycle exhaust back into the case, or gearset to keep it happy and lubricated.

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