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 [:o] ). 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?

RE: Seidel 7-70 radial: Help me decide!
 

Actually here's a photo of the most recent version (the one being sold by UMS).

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!

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. [:o]

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

On the other hand, the parallel rocker rods look would certainly look right in a Camel! :D

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

RE: Seidel 7-70 radial: Help me decide!
 

You have already decided.;)
There are a couple of threads in the glow engine section.

RE: Seidel 7-70 radial: Help me decide!
 

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]

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".

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! :D

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...;)

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.

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.

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!:eek:

RE: Seidel 7-70 radial: Help me decide!
 

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

;)

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?

RE: Seidel 7-70 radial: Help me decide!
 

http://www.youtube.com/watch?v=0xe1LL1IC7Y

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.

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.

RE: Seidel 7-70 radial: Help me decide!
 

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

I'm sure it's available somewhere. But I somehow don't think go-cart racing is a big thing in Japan!

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 ;).

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

RE: Seidel 7-70 radial: Help me decide!
 

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... ;)

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."

RE: Seidel 7-70 radial: Help me decide!
 

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.

http://www.modelbouwforum.nl/forums/...1-p1010694.jpg

http://www.modelbouwforum.nl/forums/...0-p1010687.jpg

http://www.modelbouwforum.nl/forums/...3-p1010706.jpg

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!

RE: Seidel 7-70 radial: Help me decide!
 

But he'll look great on the top end of that Immelmann! ;):D But, yeah, Teus, thanks for posting those photos. I just keep feeling that the 770 is WAY to much engine for a 1/4 model but seeing it in an EIII makes me think it's got to be in the right range and shouldn't be too big for something like a Pup at long as I only planned to use maybe about 1/4 throttle. So maybe I do "need" one.

BTW, Teas, do you know if any of the guys using Seidels on their WWI models are using them with "collection rings" ("ringscharrdämpher")?

RE: Seidel 7-70 radial: Help me decide!
 

BTW, compare and contrast: 1) 1/4 scale EIII with $1000+ functional radial engine and 2) my 1/6 scale EIII with $25 dummy covering a $120 Magnum engine!

RE: Seidel 7-70 radial: Help me decide!
 

Don, something to consider about Seidel engines. Where to you get it fixed when its needed??? If the service from Seidel is as bad as reported then what?

RE: Seidel 7-70 radial: Help me decide!
 

Allright Don......will you PLEASE just forget the romance of and dreaming about, using the Seidel.......
Proctor had one in a 1/4 scale Neuport 28 that was successful and flew very well (Dick Hansen flew it & I have a video of it)
Charlie Nelson used that engine successfully in a Waco model that was in a lot of contests including Top Gun. He found the engine very reliable.
I had one of the original ST-770 and it was a beauty. But I, like everyone else, admired the craftsmanship then ran it and marveled at how well it functioned before I put it up to display it.
I had the intentions of putting it in the Proctor N28 because the design of the model was well suited for adapting that motor to it and Proctor had a motor mount available for it.
My 2cents:D

RE: Seidel 7-70 radial: Help me decide!
 

Reg buddy. Please post the vid of the Seidel in the neuport.

RE: Seidel 7-70 radial: Help me decide!
 

Don a G 38 is way more than adequate for a pup, The Seidel would be a treat in one built with the nose the correct length though and ballast probably wouldnt be a requirement. It would take throttle management not to fly the wings off it though. The reduction drives you keep mentioning are really for 1/3 scale models where a 30 inch prop is desired. One turning a 24 or 26 inch prop on a 1/4 scale would be perfect as most of the rotarys spun an 8 foot prop.
Doc

RE: Seidel 7-70 radial: Help me decide!
 

I'm really working hard to get past the "romance" of having a Seidel and trying to decide rationally if there is an advantage to using one. I do believe that the Seidel is currently the most economical radial current available...by several hundreds of dollars. The fact is that I just wouldn't pay $1,500 for an engine...let along $2000 or $4000! But at about $1000 the Seidel is within range (as a one time purchase to be used on a number of models over the years). But then for the same money I could get three DLE engines and keep them in three models.

In terms of scale appearance, as I illustrated above, a good quality dummy engine will be more scale than the Seidel (but the Seidel definitely looks more scale than any of the other radial engines). But there's a certain scale quality to having a functioning round engine even if it's not quite scale. Curiously, I find the 7-cylinder 770 to look "more scale" than the 9-cylinder Seidel. The 990 just looks "too busy" in a WWI cowl and looks more like a Pratt and Whitney. The space between the cylinders on the 770 gives more of the impression of the space on a 9-cylinder LeRhone or such.

Yeah, I just wouldn't have the heart to put a Seidel in a "cage." I'd have to let it "run free." :D I mean, if it really loves you, it'll come back right? :D:D

http://www.youtube.com/watch?v=FaOki5eGvy0

RE: Seidel 7-70 radial: Help me decide!
 

Don, I got an email from Hobbyking. They have a Seidel 770 radial in stock for $1199. You can check it out :)

RE: Seidel 7-70 radial: Help me decide!
 

I've gotten a slightly cheaper quote directly from UMS. But this is without doubt the cheapest (a relative term of course) radial engine available. But then most people are saying you have to have a collection ring which adds another couple of hundred dollars.

RE: Seidel 7-70 radial: Help me decide!
 

So here's another way to think about it (i.e. another way to rationalize the purchase). The Seidel might cost me $1000 but if these engines have a pretty good resale value so even if I only got $500 for it down the road, I'll still only have paid $500 for the fun of flying with one. And if I do decided to keep it longterm then $1000 is not such a bad investment for a guy who loves WWI models.

RE: Seidel 7-70 radial: Help me decide!
 

You buy one and I will give you $500 for it the next day!:)

RE: Seidel 7-70 radial: Help me decide!
 

Do I at least get to run the engine? Or do I just have to stare at the box? :D I'll be selling my Leica (hopefully this summer) and I imagine I'll end up losing perhaps $300 on the deal after a few years. But that's well worth it for a chance to shoot with this legendary camera. I figure the Seidel will be similar. That's assuming, of course, that I don't fly it into the ground, which is always a possibility. Not much chance of that happening with a Leica!

RE: Seidel 7-70 radial: Help me decide!
 

Sometimes you just have to bite the bullet and go for it [sm=thumbs_up.gif]
Just get it and enjoy! Or save it for that special model down the road.
Chances are the more you contemplate it, the harder you might be able to justify the investment.

On the subject of what model to power, the following might be a useful reference:
An article in the may issue of RCM&E mentions a 1/3 scale (153", 50 lb) albatross CIII powered by a ZG 62 fitted with a reduction drive.
The ZG 62cc power output is 4.3 hp (standard silencer) or 6.6 hp (tuned pipe).

On that basis the 4 hp ST 7-70 might be a slight overkill for anything but a very heavy draggy 1/4 scale but then again it doesn't need to be flown full blast, and it would certainly help with the balancing!

RE: Seidel 7-70 radial: Help me decide!
 

Here's my Rationalization of the Day: Lots of guys spend Big Bucks on fancy radios. I don't. I've always flown with a basic $200 radio. Lots of guys spend Big Bucks on kits. I don't. WWII guys regularly drop $300+ on retracts. Not us WWI types. The craziest I've gotten is spending $100 on a pair of spoked wheels.

Thus: I deserve a Seidel! :D

RE: Seidel 7-70 radial: Help me decide!
 

Sure is a pricey way to put ballast in an airplane but OH the sound. Abu you justify it as well as I 've ever seen done. Go for it.
Doc