Toad

I just recieved a new Profi .8 (.049) today from Jim Booker.
On first impression I must say I am impressed and not so impressed.
As you know I built a couple of my own engines last winter based on the "cool" idea of the venturi placed 90 degs from the standard position in front of the cyl. I was amazed to see the supplied venturi has a throat dia. of .195 as compared to the venturi I make for my modified Norvels, which I make to .190 the casting in real life is much better than in the pictures of this thing on the internet. I was also surprised a bit with the piston sleeve fit. There is absolutly no pinch at all at TDC. That is the part I am not impressed with, but I am not sure that we really need all that pinch anyway. I recieved the one that accepts the Nelson Plug, with the plug installed I was satisfied about that pinch issue in light of that the piston did not leak at all, I mean "0". I have not run it yet. another nice thing is that it is truely very light compared to my GZ's and my Cyclon. It is only very slightly heavier than my homemade engine that has no bearings in it. the bearings in this thing have a very velvet feel to them just like the Cyclon That Galbreath setup for me. One of these first weekends I plan on a heads up test between all my best 1/2a's on the same prop, fuel and plug. I will run them within the same hr/weather condition just for comparison. Rumour has it that this is the Cyclon/Fora Killer. I hope so. Cool little engine. Here is a picture on Jim's site of it. I am more impressed with the looks in real life.
http://www.flycontrolline.com/photogallery/MVC00029.JPG

combatpigg

My Feedback: (3)

Looks like they studied a Cyclon and decided to see where improvements could be made. That would seem to be an impossible task. My Fora had noticeable pinch before the first run, then after that it just did a good job of maintaining a compression seal. Jim lived nearby until a few years ago, I think he moved East to work for either Hobby Lobby or Horizon?
Anyway, hope you get many years worth of use out of it, I would break it in on a Blink if I were you.

GrahamC

Now that is cool! I have been wanting one of those too but other than just wanting one to mess about with I haven't been able to convice myself to spend the $$$.

Jim Booker had this to say (on the NASS forum):

very cool indeed!

cheers, Graham

DeviousDave

The early Cyclons I have don't have much pinch either, but the third later one does. I think they did this to give people lots of power (FF motor, remember-short runs so pinch isn't so important), but later fitted them for better life.

Man, I really want one of these...

Toad

I'm thinking that ABC construction would require more pinch to allow for correct fit when hot, not the case with AAC, both the piston and sleeve expanding the same, so no pinch required. Just my thinking on it.

peterburford

Much faster, of course, to have a good compression seal without the friction of too much taper and pinch.
Better, but more precision is needed, to construct to this accuracy rather than to run/wear to fit.
Peter

combatpigg

My Feedback: (3)

Engines like these that can put up with the punishment year after year and provide so many thrills are a bargain. Anyone who has the eye sight, motor skills and desire should try this stuff while it is still around.

Larry Driskill

Toad, How about I send you my Profi from the first batch ( 2 or 3 years ago) and you compare the two for us?

Toad

I would probably forget to return it...accidently
Here is what I plan on doing
Nelson Plugs, 40% with all castor fuel, same actual propeller used on each, tach used will be TNC, I will run them within the same hr If I can. Engines to be compared will be my best VA, best modified AME .049, and .061. Cyclon .061, GZ .049 and .061, and the Profi .049
Not really fair to compare the .049's with the .061's other than it should be interesting. I cant do it this weekend. but the next.
THis will require me to change mounts and stuff, Im gonna be busy. I will try to get pictures of the tach numbers. If I have my own engine ready by then I will throw that in. (version 3 casing # 8) I'll post the info on my site, it needs a revamp anyway.

peterburford

I like the venturi at the left.
The inlet port then helps the shaft counterbalance.
Peter

lildiesel

That venturi set up would lend itself to building a sweet little 1/2A combat plane.

Japanman

i had a look at J.B`s site and i see the new 049 is 3K up with some combat props over the old one- you might be onto something there.

J.M

Profi America

Guys,
Com'on, has no one run their engine yet? We got them out there and no body has time to run them! Less talk, let's get going! Michael Wilcox has some new 1/2A combat airplane samples coming for test with the new engine, can't wait at this end. Larry's LiteHawk will do the job anyway. Free flight testing at muncie next month.
Profi America

DeviousDave

Any word on the .061's yet? I'm more of a pylon guy and could use all the torque I can get!

Profi America

The one sample .061 is now in Doug Galbreaths hands. He will be doing some testing of his own. Our own testing was extremely positive. It has considerably more tourqe than the .8cc so correct prop size is going to take more testing. I also have not had a chance to run hotter Turbo plugs in the engines but it seems that the availability of various heat ranges should be a benefit. Right now the Nelson plugs are about 500 better than the turbo plugs.

1cc will probably be at least 8 weeks away. Send a pm if you want to be on the list.

Let's hope for better weather tomorrow.

Profi America

Japanman

Jim,
On your site you mention some rpm figures- could you be more specific about the props used?

Stefan

combatpigg

My Feedback: (3)

For RC speed, it's gotta have a 4 pitch. For the sake of comparison, rpm figures with a 5x3 will work out the same as with a 4.2x4......but the range of plane sizes that this prop works well with is very small.

DeviousDave

I wish we had more choices in props, as square props are the way to go in pylon. APC makes props that work really, really well in this RPM range for Pylon applications, but they are electric props and you have to excercise a great deal of caution running them on a glow motor that belly lands.

The kind of power and RPM we are talking about would have made and F5D electric plane do 150-160mph ten years ago.. It's incredible to see .049's and .061's pumping out this level of power.

Profi America

Most Props I tested have been Epoxy/carbon like Larry Driskill sells. These are very good high performance props and safe at these RPMs. I sometimes worry about plastic props in these rpm ranges. There are plenty of props out there if you look. Some take more work such as the carbon ones from Steve Wilkes. George Cleveland has a selection. Doug Galbreath has some as well. But other than some APC you wont find these in the hobby shops.

However the one prop that most people can get and is common to the FF guys is the APC 6x2. This one I have at 31,100. Larry's 4.6x2.8 has now gone over 35K with 40% nitro.

It does not like the APC 5x3 so I am going to measure that one and see what is up. But, com'on why am I doing all the work here and everyone else is not doing anything?

Regards,
Profi USA

Toad

Well, I started the thread, and stated I could not not do any tests last weekend. That is because I went to my daughters college graduation. (very long drive) So I will post the numbers I get along side the other engines run under the same conditions when I get the earliest chance. I wish playing with models is all I have to do, unfortunatly the fun stuff has to wait for a slot of my time.
I really did not think a vendor would chime in on this.

DeviousDave

I might get flamed for saying this, but for Pylon at least, the props we use on 1/2A's, at the RPM we run them at are not the way to go. The "good" glass props sold for 1/2A's are meant for CL Combat planes that weigh nothing and don't have the same acceleration requirements as a pylon ship. A CL combat ship needs to have a boatload of thrust, with speed secondary.

Prop efficiency falls off in a big hurry under 6" diameter, but unfortunately 1/2A's don't have the power to swing a 5-5, or 4.7-4.7 like is common in electric pylon. These airplanes go much faster than 1/2A's do at lower RPMs, so clearly there is room to experiment. I'm willing to bet that the APC 4.5-4.2 will be a really good pylon prop for a Cyclon/Profi/Fora, and the 4.1-4.1 would be good on a hotted up Norvel.

From memory, the Cyclon .06 Top3 will turn an APC 4.7-4.7 at 27,500 with 25% and no pipe. That's FAST, and it will unload a lot in the air, even if the engine isn't in it's 'happy place' with it bolted on. Man, I have to get a 1/2A Sliver finished... When I got into e-pylon, an Aveox powered F5D plane weighed 31oz and turned that 4.7-4.7 at that same RPM in a 1/2A sized plane (180 sq. in). I never wanted to fly them because they were too hairy to launch and all the equipment at the time was hand made. With something like this Profi, you could build the same plane at 130sq. in., and 9oz. I'd almost be afraid to fly it...

DeviousDave

I worry about plastic props too. At this performance level, props are inspected every flight, and thrown away if there is any sign of stress from running or landing. APC props are like, $1.80, which is part of the cost of doing business at this level. Heck, a $7 glow plug per flight is acceptable to a lot of guys.

I wish I knew where to get a square, or at least high pitch single blade prop. I know CS used to sell them, but after having a few of their engines I wouldn't want to trust a one-blader made by them. I was able to make a 1 blade prop from the Graupner CAM 4.7-4.7, but never got it completely balanced dynamically. It just needs some time, it was done for NATS testing in the final days prior to leaving.

DeviousDave

BTW: What are you using for a tach? Mine won't read high enough to test a current ballraced 1/2A or 1cc motor-it stops reading at 31k.

Toad

I use the TNC tach, it measures up over 100,000 rpm very accuratly. they are costly, around $100.
What I like about it is that you can get the reading from a very safe distance even on these small props, easily from 2-3 ft.
Here is a link: http://www.darrolcady.com/Accessorie...sories.htm#TNC
.05% accuracy...cant beat it.

RocketRob

My Feedback: (1)

Second on the TNC.
Bought one and won't look back at anything else.