combatpigg

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CaffeenMan's recent post got me thinking about the merits of trying a .15 powered speed plane. I've always wanted to do one but didn't want to spend money in that direction compared to spending about the same to fly Nelson .40s.
A .15 powered plane would be a better fit at my field than what the .40 sized planes are now. I haven't flown the last .40 sized plane I built yet since a freeway overpass was put in ..in DIRECT alignment to my field's normal lengthwise flight path.
I'm not sold on the need to fly the piped versions of these engines to get satisfactory results. I think the "combat" engines with open exhaust will do just fine, run a long time without endless repairs and keep the cost down to the initial investment plus about $10 per run when you factor in broken props, blown plugs and fuel. That's rich enough for my blood. Not dealing with the bulk of the pipe system is also a bonus but I admit that the piped engines are way more musical to listen to.
I'm going to start looking for Foras and Cyclons at the NASS message board and at Ebay.

speedracerntrixie

My Feedback: (29)

After setting up my sons Traxxas off road truck I had thought that the 3.3cc engine that it came with would make a great speed engine. It tuned easily and based on how fast the truck is it has gobs of power. Then I complicated the idea and thought a couple of them on a 45" hand launch Pond Racer would be the bees knees. In the end the Pond idea was simply added to my bucket list of airplanes I want to build.

combatpigg

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It would be revealing to see how much prop the Traxxas engine can tolerate. From there you could estimate the static thrust and speed potential, then go about figuring how much wing it will take to be feasible.
It looks like APC has a 6.5 x 6 pylon prop available, as well as a few others in that size range but smaller. A scaled down, simple, "Q-350" sort of plane would be a good way to get started.

aspeed

For the Fora and Cyclon's you could check the MACA or flying lines site too. Lots of guys have outdated ones from F2D and like money. I got an Axial .28 I want to try for B Speed (control line) I was after a Novarossi, but for $20 I couldn't let it go. 18,000 RPM on a Revup 7-10" prop. with no pipe. I was reading an old magazine that said 20,000 would be the minimum on that prop to go 200 mph. They had skinny lines and unlimited nitro then. I think rc would be faster with a clean plane. I had to make up a thrust washer and needle valve/venturi, and turn off the fins for it. I will make a Turbo plug head too if I ever get a plane built and find a paved field.

combatpigg

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Yes....both A & B Speed have some of the most unbelievable times being turned in.
I'll check over at MACA and Flying Lines. There's no less than 5 or 6 guys within a 50 mile circle of here who fly [or flew] FAI Combat.
I've never heard of your Axial .28, it sounds pretty awesome. Same size as most .25 to .36 engines..?
Speaking of which, there are usually Nelson .36 Combat Specials on Ebay if you want a terrifying amount of power with open exhaust.

aspeed

The Axial is similar to the Traxxas type dune buggy motors.

combatpigg

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I see......... it looks like you made the venturi, spray bar, cowl and prop nut..?
If I ever see one of those engines for a low price I'd have to give it a try.

MJD

My Feedback: (1)

18-20k sounds like awfully low rpm for that engine. Probably better off running about 6" pitch in the mid 30's to get the hp out of it. I thought that was the general trend in B speed these days.


In general I think it is safe to say that for any given engine, you can always go faster RC than C/L. The lines (or line) represent a pile of drag. A good example is 10cc F3speed - running 25-26k on OPS/Picco/whatever engines that are essentially C/L speed engines, they are achieving 240 mph some regularity. That will never happen C/L.

I would believe that an F2D .15 is capable of the high hundreds in a dedicated speed airframe. I wonder if 200 is possible? Considering the F2A 2.5cc CL speed record is about 208mph, I have no difficulty believing that one of those engines could haul the right airframe in the area of 220mph without the impediment of lines.

Steve Wilk has a nice assortment of 5" props that look suitable, esp the 5x6.

aspeed

I would go for the Fora or Profi before the Axial or most of the dune buggy ones with the exception of the Novarossi. A new .28 is only $125, and I think the .15 might be too. A pipe is better on those though. Like CP says, it can be a hassle. I flew F2A a long time ago, and the lines do slow you down a lot. They had 52 ft, now it is 60 ft. The AMA speed rules always go to larger and/or longer lines every time 200 mph is the new record. I like the control line because of the accurate measurement of speed. RC and a radar can be fooled with a dive. There is also the fact that I can't fly RC safely at those speeds. I think the F2D Proto Speed planes are going a bit over 100 mph in the north west, but haven't seen many times published. I think a 5 or 6" with a 6" pitch would work. The F2D combat prop I have is 6.2 - 5" but very thin and narrow. I think a speed plane needs pitch just in case it hooks up. The old A Speed planes used a 6-7 normally. They had a lot of nitro allowed, so now things would have to rev higher to get the speed. If using a Fora or whatever, you could cheat with the venturi size too. They only allow 4 mm intake and 6mm on the muffler

aspeed

I will start anew line here to separate my thoughts a bit. My Fora .15 went 20,500 with a 7-5" MA prop this compares to 17,000 to 19,000 on an LA to old Rossi, Magnums, Taipan.... I made a new Turbo plug head for my ASP/Magnum, and it matched the Fora(and blew a plug)which also uses that style (Nelson) plug. A lighter load like the toothpick F2D props may change those results a lot though (or likely break the cheaper Chinese stuff) There is an FAI class IIRC that allows any size line as long as it passes the pull test, and it is much faster. I think a guy was about 230 mph with a piped F2A speed motor that was bored out a little. Pipes really help with speed, it is like night and day.

combatpigg

My Feedback: (3)

My second hand knowledge of the Fora .15 is it runs harder than most others because the crank case has been "stuffed" to increase pumping efficiency. The piston skirt actually passes into the backplate. I do not know anything about the different versions there might be of this engine, or if there is just 1 design for combat, free flight and control line.

About the Axial .28 turning a 7x10 prop 18,000 with no pipe.....it's able to accomplish this impressive feat because it is not a pipe timed engine, [I'll bet]....?.
I'll bet it's set about 160 degrees if not less....?
I would like to see what a Nelson .36 [low timed] could turn that 7 x 10.

aspeed

It is 160 degrees. I don't think the pipe made any difference in rpm. It wasn't on the pipe I didn't think. It was a few years ago. My K&B RR .29 revved about the same with no pipe. 20,000 and a 10" pitch works out on paper to about 200 mph (if it is 100% efficient, doesn't unload in the air, plane has no drag, prop blades are wide enough...) The Nelson .36 would surely beat that. I think the 40 Nelson pylon planes go about 200. edit, I also had to drill and tap the crankshaft on the Axial for a 10:32 stud, I made probably over 50 spinner nuts for most of my motors. I hate spinners at the field, but like to use starters

MJD

My Feedback: (1)

Where is the go-to place in North America for F2D engines?

combatpigg

My Feedback: (3)

MJD, that is a good question.
Doug Galbreath of course handles Cyclon. You can also deal directly via email with Aleksnadr Kolmykov of Cyclon. Galbreath was less expensive than going through Mr. Cyclon, but I had to wait much longer going through Mr. Galbreath for a 1cc engine.

FORAs..it used to be George Cleveland of GRS Models but I'm not seeing any search results for them. I've heard of a Canadian outlet and should get more detail soon.
Believe it or not, CS [Chinese fame] list a F2D engine but they only work with retailers. In this case, Bill Hughes would be the contact and I believe he is still actively doing business.

Rich Lopez who writes the CL Combat column for Model Aviation is an excellent all around source of knowing where to go for everything. I haven't contacted him yet.

The guy who handles Profi ..Jim.......Booker. He was the guy a few years ago. I just don't see Profi listed in the win column locally, but that can just be a regional bias.
Darren Albert is another name . He bought up Kustom Kraftsmanship and he is very active in the sport.
I'm "working" at it..but the usual sources always seem to be sketchy. To this day, I do not know if any of these combat engine builders offer CL Speed versions of their basic engines or not.
My hope is that with normal 1/2A equipment a .15 powered plane will be a step up from the .061 powered planes. Not just in actual speed but also apparent speed.

MJD

My Feedback: (1)

This is what had me puzzled yesterday - GRS no longer shows up on the web, and Doug Galbreath's web page makes no mention of anything other than a few small engines and accessories. Guess I should call. I'd go to Jim Booker if I wanted a Profi F2A engine.. still sorely tempting by the way.

aspeed

http://aerohobby.ca/store/ Is good and in Canada too. I have heard an email is quicker than using his site. He is very active here and speaks their language and carries his own design planes for the 80 MPH combat as well as the F2D. On the site, you have to register to get prices. I think last time I looked the Fora was $250. I got my Fora .049 from him.

MJD

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Aha! Nice site, thank you. The Zalp seems to have quicker lap times, by a hair.

MJD

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Hey, does anyone here have an idea how much fuel an F2D typically burns per minute? I'd like to get an idea how much real estate is needed for 3 minutes of fuel.

aspeed

I think 2 oz. go in the plane easily. That is enough for a match. I don't have the rules, but likely 3 minutes plus maybe a minute warmup? They have a fairly small venturi 4 mm. Someone else may be more knowledgeable than me. I don't compete.

combatpigg

My Feedback: (3)

The venturi size would need to be opened up judging from appearances.
Yaro shows pictures of his reworked FORA crank, and he says that improved the lap times considerably
The bearings [according to him] need to changed out to higher quality. So...it makes me wonder if Cyclon, Zalp or Profi use good bearings or not. Yaro noted a difference in lap times with Swiss bearing with the grade 3 tolerance. Tighter than that is no good. Also, the FORA's piston can swell past it's original size and stay like that after it cools down. This comes from a really smoking run on a hot day. The piston either needs to be resized or elsed matched to a worn out liner at that point.
I can see right now that I need to solicit some more opinions. I'm leaning towards Cyclon..but first I'll contact Rich Lopez who writes the CL Combat column for Model Aviation for his advice.

MJD

My Feedback: (1)

I found myself wondering of a counterweighted single blade F2A prop might be the ticket.. these are typically about 6" diameter (3" radius) but 6 - 6.5 inch pitch versus 3.5-4 for the combat props. I would not expect piped F2A rpm but I wonder if the F2D engines could spin these up in their happy zone, 32-33k? Not sure how the load factor drops when you shuck a blade, but if it was kind of a wash that would be cool.

aspeed

I think they would be just as happy at 28,000 rpm and would get more bite. 30 mph on paper. 130 mph to 160 mph. Paper though.

MJD

My Feedback: (1)

But I think the F2D engines are set up for peak power around 32-33k aren't they? A .15 should be able to run there without whimpering. I believe the F2D engines have the hp for some impressive speed. I'm liking the lazy route of grafting one of these into the nose of a small lekkie pylon model and forming a cowl. I already ordered the airframe, might be a bit small, but the wing loading would end up about the same as a wild ass lekkie combo. May as well try, the conversion shouldn't be a major project. Worst that can happen is I pole-axe it into the ground out in the boonies.

combatpigg

My Feedback: (3)

I've never run single blade but I asked some speed flyers about it and the consensus opinion was that they increase vibration.
I have run "single blade" by accident with a hand carved maple prop on a TD .049 and thought I saw a performance increase. One of the prop blades blew off at half span in flight and the engine definitely gained RPM.
It wouldn't hurt to try a single blade prop if I can get reassurance that the radio gear can tolerate it. I've done 130 MPH with a $30 ASP .12 that was turning a APC 5 X 5 electric prop so I would expect to see a Russian combat engine deliver quite a bit more than that. I'd call anything less than 150 MPH a failure.

aspeed

I think a higher pitch prop will tach a fair bit less on the ground and wind up a lot more than the combat props. You still may get your 32,000 in the air. IMHO I think the combat guys are over revving the motors just to be safe on the heat buildup, and a low pitch for acceleration. Luckily the Russian motors have a good design and materials are good enough to hold together. My Fora was 20,500 on a 7-5, compared to most other .15's at around 17,000. I did get my blue head ASP .15 to match that with a new turbo head (which blew) I don't think the ASP would hold together at 30,000 on the little combat props for too long, although it went 25,700 on one before my new head.