Starting drill for crankcase pressure.

[Russell Shaffer]

I'm trying crankcase pressure on a proto speed plane.  What should I be doing to get it started?  It's a profile.

[Tim Wescott]

I'm trying crankcase pressure on a proto speed plane.  What should I be doing to get it started?  It's a profile.

No boss for crankcase pressure?

You gonna do Geezer Speed this year?

[Paul Smith]

The hole needs to be as small as you can make it.  Maybe .015" as an estimate.  The crankcase makes A LOT more pressure than a muffler. 

If you have muffler pressure tape you could put a greased wire in the hole and epoxy it shut.  Then you could pull the wire out and have a tiny hole. 

Too much pressure makes it tough to needle the engine. 

Another approach is just use a big muffler pressure tap and make an in-line restrictor.

[Air Ministry .]

Bahh.

One can ' dampen ' it , just like a stunt Engine . As in prime , turn thru ( belt over then belt thru backward , 1/2 Doz. Ea. ish )

THEN Fill the Tank , Unless youve got a CLAMP on Both Lines . Or at least the PRESSURE LINE .

Battery ON , Belt & remove Clamp as it starts .

What the bugbear could be is Flooding It thru the Pressure Line ( it usually is . So this is what you wanna watch . AND is why you keep it shut
at least till your ready to flick it . Trial to see if that or release as / when it starts . Usually a second delay - ish .

Also a ball valve in the pressure line may mean you Just Start It . As it cant backflow and flood the crankcase ..

[Russell Shaffer]

To Tim, yes I am.  That's something else you could do along with carrier.  Thanks, Matt.  I tried to start it and ended up with sputters and then an empty tank after a while. Never did actually start.  I'll be trying again with your technique.

[frank williams]

Kustom Kraftsmanship (Joe Klause , now deceased) use to sell a small pressure check valve.  It was only about 1/8 in in diameter and about 3/8th ich long and you inserted it into the pressure line.  It served two functions, it had a tiny tiny hole for the pressure and a tiny ball check valve.  You probably can find one somewhere, if not give me a call I might be able to dig one up.

[Tim Wescott]

Kustom Kraftsmanship (Joe Klause , now deceased) use to sell a small pressure check valve.  It was only about 1/8 in in diameter and about 3/8th ich long and you inserted it into the pressure line.  It served two functions, it had a tiny tiny hole for the pressure and a tiny ball check valve.  You probably can find one somewhere, if not give me a call I might be able to dig one up.

Search on "tiny check valve".  My web connection is giving me fits, but did get some interesting hits.

[Russell Shaffer]

Here you go, Tim.  You can easily build one of these for the Jim Walker and you don't have to raise your arm to fly it. 

[Tim Wescott]

Here you go, Tim.  You can easily build one of these for the Jim Walker and you don't have to raise your arm to fly it. 

I don't think that's going to do the pattern for crap.

[Motorman]

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[Russell Shaffer]

It's an LA 25 for Northwest Proto.  It's an engine specific event.  Iv'e run it on suction and bladder and just wanted to try something new. 

[Dane Martin]

For the crankcase pressure tap, I use a number 97 or #92, .006 and .008 respectively.
The check valve is a great idea for pressure. They're very common amongst RC helicopter guys. Check A-Main hobbies if you want to go that route.  I believe if the hole is small enough, a check valve is not necessary.

The OS pressure tap is a good one, as it's 3mm. Maybe a drilled out back plate bolt on the os 25? Drill out a bolt, and drill out the bolt hole in the case..... Maybe?

[Norm Furutani]

For a check valve, how about a Fourmost valve? I've been using one as a uniflow plug. Got this from Jed Kusik. I wish we had these back in the day. The free flights used to suck fuel through the pressure tap and cause over runs. We started using flood-offs for that reason.

Support one of your locals!
Fourmost check valve: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXG850&P=M

Norm

[Paul Smith]

All good ideas.

Here's another.

Fill the tank, but leave the pressure line disconnected.  Have the needle open only about a half-turn.  After barking a few primes, connect the pressure line and try to start.  If it starts up over-lean you can open the needle a little and save it.  This helps avoid flooding.

[Dane Martin]

Funny, half the people thought you were talking about a drill bit, some others thought you were talking about a stunt plane with a muffler and then they started talking about the subject of another thread lol.

The KK check valve is very good but not fool proof as in it doesn't seal completely. Also you need to flush it out with solvent after every flying session. If oil dries in it game over, get a new one. KK also made a back plate for the Cox with a check valve in it. If you're using timed pressure it will make the needle valve more sensitive. You also need the KK 128 tpi NVA for pressure tanks.

.049's are easy to flood so, get it burning off a prime a few times to warm it and clear it out Before you fill the tank. Then pinch the pressure line, fill the tank and as it starts let the pressure line go. Also, it helps to close the needle valve down a good bit before you start it then open it up to the run setting once it's running. Especially helps on high rev .049's.

The other thing is if the engine starts to run then quits you need to break the pressure quickly or the pressure build up in the tank will flood your engine through either feed or pressure lines.

What engine are you using?

MM

Oh! Starting drill, as in starting procedure! Lol.
I agree here motorman. I like what you're saying here. I, so far,  have run a bladder on all my contest models. On the os engines we fly combat planes or just fast and fun, the pressure tank works great. Give it a "choke " flip, and see fuel in the venturi. Flip that clean 5 or 6 times with the pressure line pinched off.  Combat guys use modified clothes pin style clamps. Then hook up the battery. Fires up every time.

I don't like electric starters on bushing engines.

[bill bischoff]

Just as a comment, if your venturi is small enough to run on suction, running the engine on pressure won't make it go any faster. If you can make the engine run rich, that means you are already getting all the fuel you need. To go faster you need to get more air into the engine. The natural progression is you open up the venturi bigger for more air, then at some point you don't get enough fuel draw any more. That's when you need to pressurize the fuel to get it into the engine. Also realize that you will most likely reach a point where making the venturi bigger doesn't get you anything, because other elements of the engine's design are limiting the air flow. A perfect example would be if the passage through the crankshaft were too small.

Sorry to waste your time if you already knew this. Good luck with your proto.

BB

[Motorman]

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[Russell Shaffer]

NW http://flyinglines.org/rules.bproto.htmlProto rules     

[Tim Wescott]

Just as a comment, if your venturi is small enough to run on suction, running the engine on pressure won't make it go any faster.

Inneresting article on getting speed out of the 25LA: http://flyinglines.org/kb.la25rework.html.  I'm toying with the notion of taking mine and doing all the reversible changes, or maybe just the venturi mods and a mini-pipe, and go and play with the back of the pack in NW Proto.

[frank williams]

Russell
I found a KK check valve .... send me your address and I'll mail it to you if you need it.

[Russell Shaffer]

OK, I have been listening to all of you.  I now have a .010 restrictor in the pressure line, the pressure and fuel lines are routed where I can clamp off, the needle valve is open just to where I can blow through it a little. And I have listened to the methods of actually starting the thing.  Now I'm waiting for the snow storm to stop before I try again.  Thanks to all of you.

[Motorman]

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[Tim Wescott]

Russ your link didn't work.

I'm not Russel, but: http://flyinglines.org/rules.bproto.html

[Don Curry AMA 267060]

Russell: I sent you a PM
Don

[Don Curry AMA 267060]

Russell: give me a call. See your PM
Don

[Russell Shaffer]

Frank, thanks for the offer but I don't think I need it right now.

[Juan Valentin]

Hello Russell
                         On some of the OS .40 FP engines I modified I just drilled a hole thru the beam mount and used a 3mm tap then I used a 3mm fitting. I would disconnect the pressure line when filling the tank. To start engine I would connect the pressure line turn the prop backwards just a little bit to prime the engine and then pinch the pressure line with my fingers while cranking the engine. Some times I just bumped the prop backwards a little and it would crank up. here is a Pic of one of my engines.
                                                                                                                                                                                             Juan