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Cybertom 07-04-2005 07:36 PM

Everything Radial Engines
1 Attachment(s)
This topic is a continuation of a discussion that originally started in the Flair PT-17 Stearman Thread. As it states this thread is for EVERYTHING Radial Engines. Building them, buying them, flying them, WHATEVER! It's obviously not just the engines that are of interest, but the magnificent aircraft that merit such an investment.

Here are a few links to some of the radials that are available:

Robart Radial Engines
Are currently available and are manufactured in the U.S.A.

Seidel Radial Engines
Are are manufactured in the Germany. Seidel is a small manufacturer of what are apparently good quality radial engines. They are however, as uncommon as Chicken teeth. Ziroli is supposed to be setting up to distribute Seidel radial engines here in the U.S.A. So far we have heard lots of talk and even read an advertisement in one of the magazines. If you call Ziroli about the Seidel engines they say that they are basically working on it.

3W Engines
Are currently available and are manufactured in the Germany.
[link=http://www.3w-modellmotoren.com/english/3W_Modellmotoren.htm]3W Engines[/link]

RCS Engines
[link=http://www.rcshowcase.com/html/engines/rcs215.html]RCS Engines at RCShowcase[/link]

Technopower Radial Engines
Are manufactured in the U.S.A.

Are currently available and are manufactured in Japan. Availalble at your local Hobby Shop.
[link=http://www.saitoengines.com/]Saito Engines[/link]

OS Engines
Are currently available and are manufactured in Japan. Availalble at your local Hobby Shop.

Some Pictures to get things started:

William Robison 07-04-2005 08:24 PM

RE: Everything Radial Engines
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You said Seidel, and mentioned no others. But the very first picture you posted is a Robart.

Your second picture is also the Robart radial, even though they are comparatively easy to find, they're hard to pay for. Last I heard was the bare engine at $4800 - exhaust ring, ignition, etc, all additional.

Your last three pictures were Seidels.

The Technopower engines are about as hard to get as the Seidels. I've been waiting for more than three years now for a pair of new ones.

Now to get things going, maybe in a different direction, here's the very first model radial on the market, the Burgess M-5 which was later sold under the Morton name. I remember it in the late 40s selling for $50 in my LHS complete with it's polished aluminum prop. It just barely had enough power to get off the ground. It was spark ignition, gasoline fueled. Alcohol was not an option, running on glow fuel it would self destruct.

The last picture is a real rarity, the Morton M-14 that never went into production.


Cybertom 07-05-2005 06:02 AM

RE: Everything Radial Engines
Good point!

I was intending this thread to pickup where we last left off in the Flair PT-17 thread. I could see that it might be helpful to provide links to several other engine manufactures for those who are unfamiliar so I have cleaned things up a little. I will get RCS on the page as well.

Cost of Robart Engine and accessories:
Robart R780=$4,000.00
Collector ring=$325.00
Glow Driver=$149.00

None of these engines are inexpensive because of the labor costs. I bet even the Morton M-14 sells for more than $50.00 now. Some of these engines have over twice the horsepower of others. The scale of the aircraft typically affects the price of the power plant. I think that should be taken into consideration when it comes to the price.

The only way you will see these prices drop is if the Chinese start making radials. Since the average Chinese is making only $2,000 a year they can afford to undercut everyone else. Personally I like having a variety of manufacturers. I think there is a bigger price to pay when you don't want to pay the price.

Rupurt 07-05-2005 04:41 PM

RE: Everything Radial Engines
The chinese are making radials.


It's the last one under aero four strokes: 400 5cyl radial

I think it is fairly well priced for an engine of that nature. The engines are actually made by this company: http://www.sanyemodel.com/html/ee.htm

Rupurt 07-05-2005 04:52 PM

RE: Everything Radial Engines
Another thing, that radial will be most likely be a close copy of the OS. I own the 160 twin by that company and so far I am happy with it.

Cybertom 07-05-2005 05:03 PM

RE: Everything Radial Engines
Looks like the definitely copied the OS engine. Maybe they even copied the label!:D

Rupurt 07-05-2005 05:28 PM

RE: Everything Radial Engines
With the 160 twin they copied the manual:D

"Real airplanes have 2-wings and round engines! " I like turbine planes to

William Robison 07-05-2005 05:47 PM

RE: Everything Radial Engines

The Magnum/ASP AR5- 400 was originally a 3.0 cubic inch engine, as such it was a copy of the OS radial. The later version has been enlarged to 4.0 cubic inches, if OS punches theirs out to 4.0 inches then OS will bw the copy.


Rupurt 07-05-2005 11:12 PM

RE: Everything Radial Engines
OS must have used the cylinders from their 1.20 twin 120/2 =0.60 0.60x5=3.00, whereas it looks like Sanye went on to use the cylinders from the 160. Just a guess but it seems plausible.

Rupurt 07-05-2005 11:15 PM

RE: Everything Radial Engines


ORIGINAL: William Robison

if OS punches theirs out to 4.0 inches then OS will bw the copy.

When are they gonna have their own ideas?[:'(]

William Robison 07-06-2005 12:55 AM

RE: Everything Radial Engines

From 1945 until 1955 all Japanese products were either cheap crap or a poor copy of someone else's design. From 1955 to 1965 they were getting better, and doing some original designs. During this latter period a person would buy, say, a Japanese car, drive it for two years and since they were so cheap just throw it away and buy another.

As you know, in the years following, the quality of the Japanese products has mostly gotten much better, rivaling the best products from the rest of the world in some cases.

The Chinese are now about where the Japanese were around 1970. In another few years they will probably roll right over Japan, relegating Japan to a third world position in the global economy. I just hope we can keep up with them.


Edited to remove politically sensitive comments

chasrb 07-06-2005 03:36 PM

RE: Everything Radial Engines
Tom good work on getting this started up. I am still waiting to get my Radial before I start the build of my PT-17. From what I read there is some strength that needs to built into the firewall and surrounding areas to support a engine of any power greater that the 150-180 Flair spec'd theirs out with.

Cybertom 07-06-2005 04:57 PM

RE: Everything Radial Engines

Of course I really like the approach I took which was to double up on former #32 with another sheet of 1/8" plywood on the outside. I absolutely would epoxy a block of wood on each side of the torque tube between formers #32 and #36/37 which has the effect of joining all three together at the point where the upper landing gear bolt goes through.

If you have even one hard landing you risk having the upper landing strut crack right through formers #36/37. I know because that's what happened to me. The landing gear strut will pivot on the lower mounting bolt which is supported by the aluminum cross brace. This then forces the upper portion of the landing gear to push through formers #36/37 because something’s got to give. The block of wood in-between spreads out the load so it won't crack the formers. Instead you will now bend the landing gear which is much more acceptable than cracking the inside of your fuselage.

Wrap the torque tube with some fiberglass to strengthen things up. Do all of this and she will support a 7-1/4 lb radial engine without a problem.

Make sure that when you attach the Stabilizer you have a minimum of 3 degrees incidence. 3.5 is what I wish I had in my but it's to late. Go to Flairs website and you will see that people are saying that 3 degrees is not enough. You end up carrying a lot of down elevator. I don't understand why they didn't go with 3.5 to begin with. The incidence of the main wings are 3.5 so a good rule of thumb is to also give the rear 3.5.

I started this new thread about radials just so I can talk about the Stearman...Go figure;)

HarryJ 07-11-2005 06:41 PM

RE: Everything Radial Engines
Well you guys have me convinced. I'm building the Genesis YMF-5 Waco and was planning on using the ZDZ 160 Twin. Now I'm going to go with the RCS 215 radial. Seems there are several other Waco's out there with this engine with no complaints. All other radials seem to be glow engines and the RCS 215 is gas. I saw their new 400cc version, really awesome.

William Robison 07-11-2005 06:48 PM

RE: Everything Radial Engines

The Robart engine is also gasoline fueled/spark ignition.


HarryJ 07-11-2005 06:54 PM

RE: Everything Radial Engines
Thanks Bill:

On their website it is listed as glow.

Horsepower 10

Max RPM 5,500

Weight 7 1/2 lbs.


Prop 24-8 to 32-10


William Robison 07-11-2005 07:06 PM

RE: Everything Radial Engines

I'm sure I've seen the Robart as a sparker - maybe coil ignition is an option. Extra cost, of course.

The Morton/Burgess M-5 was gasoline only, it wasn't strong enough to run on alcohol.

The early days of Technopower also had an ignition version, but the distributor drive was a constant problem, the option was dropped.

Concerning the Technopower - you may have seen my postings giving a 6K rpm red line. The older engines have a cast master rod, 6K is the limit, this also limits the power severely. They have been referred to as Tech-NO-power engines. Latest production has a billet master rod, 8000 rpm is safe, and they now give good power.

I don't know if M. Linville will be willing to put the late master rod in an earlier engine though.


HarryJ 07-11-2005 07:09 PM

RE: Everything Radial Engines
There are other noticeable differences, 7 cyl vs 5 cyl, 10 hp vs 13.5 hp, 7.5 lbs vs 11 lbs, $4475.00 (w/exhaust ring & glow driver) vs $2950.00 complete.


HarryJ 07-11-2005 07:14 PM

RE: Everything Radial Engines
I talked to the Robart guys at the AMA Convention in California back in January. They had a display engine there and I thought it was a gasser also. Maybe their ad was a typo. I had an old Morton, used it for a paperweight.


Cybertom 07-11-2005 07:46 PM

RE: Everything Radial Engines
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Just to clarify,

I own a R780 and they do not sell or offer a GAS version. It's not very easy to take a GLOW engine and convert it to GAS:

1. Your valve timing would need to change completely because GLOW and GAS do not behave identically when ignited.
2. GAS would require that bearings such as the connecting rod be changed to needle bearings because the lube is much thinner, or the engine would have to hold its own oil sump which it idefinitely does not have.
3. The additional heat generated by a GAS engine would probably require that the carburetor be on a heat isolation mount to prevent vapor lock.
4. No location exists on the R780 to install sensors that will pickup the timing of the engine.
5. Nobody I know of has a spark ignition for a 7-cylinder engine. 5- Cylinder GAS is the only thing I have seen.

The RCS engine is a very good engine from everything I have read. Looks like it's popular to pair that up with the Genesis WACO kit.

As far as I know, other than Ziroli, I am the only other guy who flys a R780 and has posted anything about it. Maybe their out there somewhere but my guess is that vast majority of R780 engines are bolted to hangar queens. So it's a $4K engine, so what! Just for comparison look at the jet guys. Nobody even bats an eyelash at $4K. I believe in flying great aircraft not just looking at them on the ground...makes me want to puke!!!

My R780 on my Flair Stearman:

Video Liniks (Hear the R780 Run and Fly) These don't seem to work anymore? -Moderator....
[link=http://www.cmac.org/phot/videos/pt17_stearman/PT17_1stFlight.wmv]Flair PT-17 1st Flight[/link]
[link=http://www.cmac.org/phot/videos/pt17_stearman/BigPlaneFly.wmv]Flair PT-17 C.M.A.C. BIG Plane Fly-In[/link]

William Robison 07-11-2005 08:02 PM

RE: Everything Radial Engines
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The only reason there's no seven cylinder spark on the market is that no one has wanted one. There's nothing to keep one from being made.

Here are three shots of a seven cylinder spark engine, a Technopower 7C, a really early one.


HarryJ 07-11-2005 08:04 PM

RE: Everything Radial Engines
Thanks Tom for the clarification. Very nice job on the Stearman, the plane and engine look like they were made for each other. I imagine a 7 or 9 cylinder radial would require an extensive timing sensor system that would be weight and space consuming. Otherwise there would be some out there.


Cybertom 07-11-2005 08:09 PM

RE: Everything Radial Engines
That's true but I guess I'm saying that if it were done today it would almost have to be electronic ignition and not a mechanical distributor. I have not seen any 7-Cylinder GAS engines. Personally I think that they would sell more GAS engines if they had a 7-Cylinder. I don't think it's as workable because your cylinders are much closer together which will generate a lot more heat. I think that's why we don't see them. Heat is an issue.


Very cool TechnoPower engine. Mark should be giving you extra special service.

In a way it makes me sad that TechnoPower moved out to Califormnia. I love Ohio, and that was another cool little business we had here that I could checkout as I walked around Chagrin Falls. Of coure this was after I stopped at the Water Fall and got myself an icecream at Baskin-Robbins.

Cybertom 07-11-2005 08:13 PM

RE: Everything Radial Engines
You know what’s funny. They made glow engines so they could dispense with all of the complexity of having ignition systems. Then we go back and screw it all up by having our glow drivers and heavy NICAD battery packs in the airplane. It really doesn't make any sense to me. Forget the GLOW driver and give me back electronic ignition and GAS!


Looks like we have a full house tonight!

William Robison 07-11-2005 08:33 PM

RE: Everything Radial Engines

TP moved west with the change in ownership. The update on the design has been a long hard trail, but the end is in sight. Mark says he's about to start a run of the "C" series engines, then a batch of "B" size, then finally he says he's going to put four or five of the "A" engines together. I've been wsaiting molre than three years for a pair of 7A engines.


...Mark should be giving you extra special service.
It is to hope.


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