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Seidel 7-70 radial: Help me decide!

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Old 07-19-2010, 06:54 PM
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Default Seidel 7-70 radial: Help me decide!

So I'm going back and forth on the idea of ordering one of the new Seidel 7-cylinder radials manufactured now in India by UMS Technologies:

http://www.umstech.in/products_allma...Engines&page=1

There are several differences between this engine and the one originally manufactured in Germany years ago. The most obvious differences are the all "silver" cylinders and pipes of the new version vs. the black of the old one and also the fact that the old version used a 6-bolt prop hub (which honestly I like MUCH more [] ). Of course, one other change is that the newer India-made version sells for almost $1000 less than the original!!! Ordered direct it would cost about $1,100 including shipping. With the strong yen this might be the best time for me to buy one.

But several doubts remain. First and foremost is whether I really have a purpose for this engine. What range of models would it fly? Would it be ridiculous over-kill to put it (initially) in a 1/4 scale Pup, for example? It's 23cm diameter would fit perfectly within the 26cm cowl! But at 1/5 scale (and a 63" wingspan) the model would probably fly with a 72 4-stroke and definitely with a 91. So at 1/4 scale a 120 would probably do the job. The Seidel has 7 0.61 cylinders and is rated at about 4HP (and weighs about 2.6 kilos). It's probably WAY too much engine for the 1/4 scale Pup. But that might be a good "first model" to fly it in.

Any other considerations? Any other warnings? Should I? Shouldn't I?





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Old 07-19-2010, 06:56 PM
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Default RE: Seidel 7-70 radial: Help me decide!

Actually here's a photo of the most recent version (the one being sold by UMS).
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Old 07-19-2010, 07:01 PM
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Default RE: Seidel 7-70 radial: Help me decide!

The more I think about it, the more obvious it seems that this is more an engine for a 1/3 scale Pup! Or one of the 1/4 scale two-seaters with a 120" type wingspan. Given that it turns a 24" prop, that probably wouldn't even clear the ground on a 1/4 scale Pup!
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Old 07-19-2010, 09:05 PM
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Default RE: Seidel 7-70 radial: Help me decide!

Hmm...so in terms of power perhaps the Seidel 7-35 is actually closer to what would be needed in a 1/4 scale Pup. This engine is rated at 2HP and will turn an 18/6 prop. The problem is that with a diameter of 186mm it really isn't a scale size and would have to be covered up with a dummy anyway. []

http://www.umstech.in/product_detail...rd_20107206539

On the other hand, the parallel rocker rods look would certainly look right in a Camel!
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Old 07-19-2010, 09:30 PM
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Default RE: Seidel 7-70 radial: Help me decide!

BTW, here's a guy building a beautiful 30% Pup and using a Seidel 9-90.

http://www.gmac.org.au/Sopwith_Pup_Build.html
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Old 07-19-2010, 10:47 PM
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Default RE: Seidel 7-70 radial: Help me decide!

You have already decided.
There are a couple of threads in the glow engine section.
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Old 07-19-2010, 11:26 PM
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Default RE: Seidel 7-70 radial: Help me decide!

Quote:
ORIGINAL: TFF
You have already decided.
Unconsciously, you're probably right. But I can't seem to decide what I've decided. I WANT one. And with the sale of another bit of German technology I have lying around unused (a Leica camera) I can buy one without putting out much additional cash. But I just don't know if the 7-70 size will really work for the size models I have planned.


[sm=71_71.gif][sm=71_71.gif][sm=71_71.gif][sm=71_71.gif][sm=71_71.gif]
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Old 07-20-2010, 12:44 AM
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Default RE: Seidel 7-70 radial: Help me decide!

If it is too much, all you have to do is hold back on the throttle or limit its movement. My 1/4th Pup is that way; it's got a little too much engine in the power department. That said, the extra power is extremely comforting to have in the event you need the extra "oomph".
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Old 07-20-2010, 01:32 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Thanks, Airwarrior! You told me just want I wanted to hear! BTW, I know the Pup doesn't sound like a very bold choice for someone who's always going on about not wanting a "me too" model. But I think I've at least got a "new route" up the Pup mountain...to borrow an analogy from mountain climbing. By enlarging the DB 1/5 plans (based on the Replicraft drawings) and then supplementing them with scale ideas from the Replicraft Pup, I'm pretty sure I can come up with a Pup to call my own. And if it's got a radial engine in the nose, all the better!
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Old 07-20-2010, 02:13 AM
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Default RE: Seidel 7-70 radial: Help me decide!

I know exactly what you mean when it comes to the "me too" models. I only built the Pup because of its ease of construction, long history of great flying, and copious amounts of builder support (important things considering it was my first attempt at a kit). Any models in the future, though, will probably be on the rarer spectrum. I have a bit of a hankering for a 1/4th Pfalz DIII actually...
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Old 07-20-2010, 05:43 AM
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Default RE: Seidel 7-70 radial: Help me decide!

BTW, I just checked and the full-scale prop on the Pup (or more precisely on the Gnome since props are matched to engines not aircraft) was 2.55 meters..or just over 100" inches. So the Seidel 770 couple swing an exactly scale size (and thickness) propeller.

At 2.6kg it is a real heavy-weight. But then the Zenoah G62 weighs in at 2.3kg. And I did end up having to put 800g of lead in the nose of my Snipe.

It just seems that the ST770 is really more like the G62 in terms of power. Do people put G62s in 1/4 scale Pups and Camels? Seems like the G62 is a 1/3 scale engine. So it seems like the ST770 would be too.
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Old 07-20-2010, 06:07 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Here's a full-size print of the ST-770 sitting in the 26cm pot that's just right for a 1/4 scale Pup. The second photo shows the smaller ST-735.
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Old 07-20-2010, 04:16 PM
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Default RE: Seidel 7-70 radial: Help me decide!

That is a way cool engine, abu.[sm=thumbup.gif] The only thing that would be way cooler would be a true scale rotary engine, but then who would want to fly one with all the torque and gyro problems that causes!
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Old 07-20-2010, 05:26 PM
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Default RE: Seidel 7-70 radial: Help me decide!

This guy, apparently. [link]http://modelrotaryflyer.tripod.com/avro.htm[/link]

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Old 07-21-2010, 11:08 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Awesome! I love the sound as he switches from low to mid to high power while setting up for landing, exactly as the written descriptions of rotaries landing describe.

I guess if you have the skills to blueprint and machine an engine, the rotary must be a major challenge. Wonder if anyone has made a scale Merlin for a Spitfire?
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Old 07-21-2010, 11:37 AM
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Default RE: Seidel 7-70 radial: Help me decide!


Quote:
ORIGINAL: fledermaus
Wonder if anyone has made a scale Merlin for a Spitfire?
http://www.youtube.com/watch?v=0xe1LL1IC7Y
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Old 07-22-2010, 01:48 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Here's where I've gotten to on my thinking on buying one of the Seidel ST-770 radials: I don't need it this very second, so the decision can wait at least until I get back from my trip to the US in late September. So there's time to think and my finances will be the same then as they are now. I don't think the roughly $1,000 price is too outrageous and it's cheaper by a good margin than any of the other radial, including Saito's 3 and 5 cylinder engines. It's also not so much more than buying a gas engine and then purchasing the gear drive to use a scale prop. And it's only a couple of hundred more than the Laser 200 twin for what seems like MUCH more engine.

But what I'm NOT finding in my internet research is lots of stories about people using a Seidel in WWI models. Of course I've seen a couple of beauties. But most of the guys who own one seem to be primarily interested in the engine rather than the model. Also I still don't have a good handle on what sort of model this engine would power. Then there are concerns about where I would get the 99.9% pure methanol (other in small, expensive quantities from a pharmacy) it uses.

So now is not the time to buy impulsively. Or at least that's how I'm feeling today.
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Old 07-22-2010, 09:18 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Yea, most buy the engine for the engine, and dare not put it in a model that could crash and hurt there engine. The guys seem to be older and retired and can barely fly a trainer but they have the money to buy them and then they sit in a box. Besides the smaller Saitos, I have only seen the Mokis fly; the 150 pulling around a 20 lb trainer like plane and a 250 pulling around a 40 lb Waco. Plenty of power. Seems most put them in Golden Age planes. They seem to be great engines, but you have to keep up on maintenance not because they are bad, but because a problem will cost you. Tear up a $200 engine and you feel bad; with this thing, you tear up a $200 part that breaks another $200 part. For fuel, find a place where they race Karts, not an amusement park but where they really race them; those guys should have a a source.
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Old 07-22-2010, 09:39 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Quote:
ORIGINAL: TFF
Yea, most buy the engine for the engine, and dare not put it in a model that could crash and hurt there engine.
That's sort of the impression I got really the "Everything radial engines" thread here on RCU. Lots of great information by some very knowledgeable people, but not some much info on people actually flying with a radial. And then there are the "collectors." It reminded me A LOT of the Leica camera forums I used to frequent. Cameras and engines are meant to be used. (Sometimes I feel like "freeing" all the poor Leicas trapped in glass cases in Tokyo Leica "museums" (aka "prisons").

Anyway, I wouldn't mind flying the Seidel. It's really not all that much more expensive than a similarly powerful Laser and even the comparable Zenoah G62 is $500. But there may be other "hidden costs" involved with owning and maintaining a Seidel.

http://www.rcuniverse.com/forum/m_31..._1/key_/tm.htm

Quote:
For fuel, find a place where they race Karts, not an amusement park but where they really race them; those guys should have a a source.
I'm sure it's available somewhere. But I somehow don't think go-cart racing is a big thing in Japan!
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Old 07-22-2010, 11:27 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Kart racing is the soccer of racing; everyone has it, but it is racing and in Japan it would be expensive. I bought up some engines when I got back into the hobby just because I wanted them; they need to be passed on so I can get something more useable. Right now an OS 1.60 twin would make me happy, or a lathe and a mill so I can make a 1/4 Bentley .
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Old 07-22-2010, 03:50 PM
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Default RE: Seidel 7-70 radial: Help me decide!

While looking through some old R/C Scale Modeler mags I saw some old Proctor ads that stated the Seidel was why they designed the Fokker E-III ( 1/4 scale). I have seen the Seidel run and fly (though not in an E-III) and it is an impressive powerplant.

J
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Old 07-22-2010, 06:06 PM
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Default RE: Seidel 7-70 radial: Help me decide!

Quote:
ORIGINAL: jtisch
While looking through some old R/C Scale Modeler mags I saw some old Proctor ads that stated the Seidel was why they designed the Fokker E-III ( 1/4 scale). I have seen the Seidel run and fly (though not in an E-III) and it is an impressive powerplant.
Teus also mentioned that the Seidel would be a perfect match for the Proctor EIII. But that seems like an awful lot of engine for such a relatively small and lightweight model. But I suppose if you flew it 1/16th throttle most of the time...

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Old 07-22-2010, 06:33 PM
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Default RE: Seidel 7-70 radial: Help me decide!

Typing Seidel and EIII in Google brings up nothing but a reference to Teus' thread about an upcoming 1/4 scale EIII build on a Dutch forum where someone mentioned using a Seidel.

http://www.modelbouwforum.nl/forums/...-4-schaal.html

Searching for Seidel+Pup yields this 30% project using a Seidel 9-90:

http://www.gmac.org.au/Sopwith_Pup_Build_intro.html

Searching for Seidel+Camel yields no hits.

So as someone mentioned elsewhere: "Seidels seem to be as rare as chicken's teeth."

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Old 07-23-2010, 03:05 AM
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Default RE: Seidel 7-70 radial: Help me decide!


Quote:
ORIGINAL: abufletcher

Typing Seidel and EIII in Google brings up nothing but a reference to Teus' thread about an upcoming 1/4 scale EIII build on a Dutch forum where someone mentioned using a Seidel.
Thats right,

Here the photo's made by a friend of my at a scale meeting in Holland. The plane is indeed a 1/4 scale proctor E.III with the Seidel 770 up front. It is not the "new" UMS Seidel but one of the original versions made in germany.






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Old 07-23-2010, 03:52 AM
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Default RE: Seidel 7-70 radial: Help me decide!

Great looking plane, but Mr. Pilot doesn't look too healthy! Tell that chap to straighten up!
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