123Cat

No, on the Fora just an ordinary nut

qazimoto

My Feedback: (1)

Isky,

that's a sleeve nut alright, but not for a Fora 15 Junior. I can make you one if you want.

I have a constant question about Davis heads and lightweight glow engines. The modeling world where I live is rich in diesel culture. I've seen only a handfull of the former conversions and almost everyone has been a disaster for c/l flying. Usually they drop the crankpin within a few minutes. The biggest disaster I've seen was a DD conversion of a TD 09.

I'll be interested to hear how yours turns out.

The Fora's are great diesels but not as good as the Parra 15D. How does 19K on an APC 7x6 out of the box sound?

Ray

iskandar taib

My Feedback: (5)

Right, that propnut is for the F2D Fora, not the Junior (which seems to have a plain old nut). Interestingly enough, there is also now a F2D diesel - in F2D, diesels aren't required to have mufflers, nor do they have to use the standard (glow) fuel. Costs the same as the 2012 Glow, though.

From talking to this friend of mine, he says the Davis diesel conversions run differently from the British-type diesels. Different fuels, especially. He likes them for Stunt, says they're very quiet if you back off on the compression.

Iskandar

aspeed

The #12-32 is the 7/32" 32 UNEF thread. The drill size is .182" to .190" and the O/D is .216" . I bought the tap just for one motor. It turns out that the FP .15 is slower than the LA .15 so I probably won't even use it much. I have the instructions and it says 7/32"-32. Like I said, I could send you the old nut you just pay shipping, or I can make an acorn nut/spinner for you if you want. I think the shipping would cost more than you buying a tap. Mine was $11.Yours are only $7.60. It is a standard size but most places don't carry it. The Fora F2D sleeve nut dia. is so big I wish they wouldn't use it. They make the crank thread so short so it doesn't bend in a crash that you have to use one. I like to use a starter on the motor because the prop is so small, too small IMHO,so I will have to make an acorn sleeve nut for that motor too. The stock one is very light though. (I don't compete, I just want to scare myself once in a while) The Fora diesel sounds interesting. I always had trouble starting diesels so I only bought one. (Frog .15) The Fora would bring them to a new level.

iskandar taib

My Feedback: (5)

Interesting..

My source of taps is victornet.com, in particular:

http://www.victornet.com/subdepartme...inch/1260.html

They list 7/32x32 and 12-32 separately, but the major diameters seem pretty close. 12-32 is .216", 7/32x32 is .219". Searching the web, I find lots of references to 12-32, but no actual nuts for sale (lots of 12-24 and 12-28 though). Apparently used in old cars and in firearms. One suggestion (I thought of it myself) was to tap out a 10-32 nut. One web site says if you start with a brass nut there's no reason to drill it, either. Wonder if a brass nut would work OK as a prop nut.

One possible source would be ABABA Bolt:

http://ababaqa.com/index.htm

A source which didn't have any, but seems to have a LOT of other stuff we might need:

http://www.boltdepot.com/Default.aspx

(Mind you, I haven't tried mailing them yet..)

Iskandar

iskandar taib

My Feedback: (5)

Yeah, the Fora (and other F2D) engines use those Russian toothpick fiberglass props with huge holes. To use any other prop, you'd have to ream out the hole something fierce.

Under what conditions (prop, application) are you using your LA and FP .15s? I'm thinking that, for Combat (wide open throttle, cut down 7x4 prop), the FP should be potentially faster, since it has more boost port area. I've been buying FPs on ebay, and want to experiment with different shaft and exhaust timings. Maybe I'm barking up the wrong tree?

Iskandar

aspeed

I normally use a 7-5 for a .15.  For rc stuff it is good, and for control line too.  I have a couple of Yuvenko combats and I tried one with an Uktam motor (Rossi copy) and it goes pretty good, I don't compete because everyone in this area is world class competative and uses shutoffs, 6mm mufflers etc.  I checked a bunch of motors I had kicking around and used a 7-5 Master Airscrew with no muffler and 10% fuel for comparison.  The AP .15 which is really only a .135 got 15,700 rpm. rc venturi.17,200 rpm with a control line venturi and radiused rod. 21,400 with a 7-4 MA.  The russian 6.2 x5 toothpick prop was 24,900 rpm.  The AP .09 was 12,800 with a 7-5 and 16,500 with a 7-4.  The OS LA .15 with a stock rc carb was 17,400 RPM and the FP with the rc carb was 16,300.  The Big Mig was 16,000 with rc carb, Norvel .15 rc carb 16,900 rpm, and an old Rossi was 19,000 rpm with a .193"control line carb..  The Cox Conquest was 19,500 rpm.  with a rc carb (Perry)  and the blue head ASP was 17,600.  An older SC .15 with BB was 14,200 rpm with a 7-6 but I would project 14,900 with a 7-5. The Uktam and Fora I didn't check because I would have to drill the propeller out.  I think an AP, LA, FP or ASP if you have them around, with a big control line carb would be good combat motors with a  7-4 or 7-5 props.  For the money the ASP is the best.  The others may be a bit lighter.         If you want to tap your prop nut, I would start with an m5 or so nut, or file the #10-32 hole til the threads barely show. It would be easy to break the tap without opening up the hole  To tap without a lathe, try to hold it square in a drill chuck or vise and tap carefully by hand checking for squareness every 1/4 turn.

iskandar taib

My Feedback: (5)

Sounds like you live near the Lovgrens, and Yaroslav Melnikov.

I think the idea of starting with a 10-32 nut is so that the end of the tap aligns itself, and then it just cuts the existing threads deeper. One web site I came across mentioned that if you use a brass nut, there's no need to drill it out first. But would brass nuts work as prop nuts??

Found another source for taps - and these are ONLY $2.79!! From the gunsmith's supply place (Brownell's).

http://www.brownells.com/.aspx/pid=6...GE-CARBON-TAPS

Lots and lots of weird sizes, and the nice thing is a lot of them are available as taper, plug and bottoming (in this particular case we only need a taper or plug). Might as well stock up on other sizes, too. Nice surprise - shipping is only $6 for small items.

I'm looking forward to carving up some .15FPs and LAs, and seeing how much I can get out of them.

Iskandar

aspeed

I just tried my #12-32 tap in a #10-32 nut and it doesn't centre itself. I have done hundreds maybe thousands of holes by hand and they hardly ever go crooked. Just use a round file to get the hole to about 3/16", keep your eye on it every quarter turn, and put a small chamfer on the holebefore you start it. I could send you the nut and or spinner and the shipping wouldn't likely be much more than shipping the tap. I will keep that place in mind for taps if I need them too.I was hoping they would have a #4-80 tap for the Baby Bee's and Tee Dee's but they don't.They are not High Speed Steel though. They will not last too long, but are probably ok for a few holes like modelers need. I think the LA's and even FP's will run fast with an f2dprop and an completely open venturi or large venturi and a bladder. As long as the rod and crank hold together. Ya, I got my Fora and a shutoffoff of Yaro, and a couple of Alex"s props to try. The AP .15 howls on that prop. It is no wonder the Foras sound so (irritatingly) great.

iskandar taib

My Feedback: (5)

Where on the Cox engines would there be 4-80 threads?? The screws on the back of the Bee crankcase are 2-56, the Tee Dee venturi is 1/4-32, the prop screw is 5-40. Victornet.com does have 4-80 taps, $11.80 each:

http://www.victornet.com/subdepartme...inch/1260.html

Yeah, reading through Brownell's site, they mention they use carbon steel because you can remove a broken tap by hitting it with a punch (which will shatter it). I suppose that's important if you're repairing an old, valuable firearm.

Iskandar

aspeed

It is for the needle valve.  I made a couple with a #2-56 and a 2mm standard thread, and they work ok but the fine pitch would be better.  Actually I could likely find something better at their company than my local one.  Maybe a #2-80 or?  The Kirnkraft .049 needles were 128 threads per inch.  I think that would be to hard to drill the hole accurate enough.  I would be out $25 to make a couple of needle valves.  Maybe I should go in business. I just bought a few Fox remote needles for $10.?? each, that is hard to beat, but they are kind of heavy.  I just haven't found any regular Supertiger style needle valve ass'ys with the hole in the right spot.  I like the stubby Fora style ones but they are too narrow for most Japanese .15s so custom is best.  marginally cheaper too if you count your time at $2 an hour.

iskandar taib

My Feedback: (5)

Ah!!! Forgot the needle valve. I was wracking my brains tryting to think of where else you'd have threads on a Cox. Yeah, those Kirn needles had mighty fine threads.. can't say I've seen any dies or taps with 128 tpi.

The most popular remote needles used with bladder tanks is the RC NVA for the OS .10FSR/FP/.15FP. Something like $9 from Tower. They're backordered at the moment because I went and ordered two dozen of them a couple months ago.

The F2D needle valves do fit the ASP/Magnum/SC .15, and is popular in New Zealand for their Slow Combat. If you're looking for 1/2-A needle valves, see if Larry Driskill (kittingittogether.com) still has needle valves for the VA. Those were like little tiny ST NVAs.

Iskandar