MikeRuth

I have a SA Paramount 52/70 that is tail dragger and weighs in about 5.75 lbs. Running a Magnum 70 4 stroke and a 13 X 6 Prop.

With the idel as low as I can get it and not stalling the engine the plane will still continue roll out at a pretty good clip.

I'd sure like to hear your thoughts on how I can add some friction to the main gear wheels.

I have added some small pieces of fuel tubing to the axel and squeezed that against the wheel, but it lossens up after flight.

Thanks

RCKen

My Feedback: (9)

Put a small piece of fuel tubing between the wheel and the wheel collar. You can adjust how much friction it applies by how tight the wheel collar is. This will keep the plane from rolling at idle, but you can still take off when power is applied.

See diagram

Ken

bbbair

Before you go and play with the wheels perhaps you should try solving the problem and not the result.

If the engine will not idle low enough you should retune the engine.
If there is no joy in this then look further.
Is the engine mounted inverted?
-This can cause the fire to go out in the Glow plug,
One solution is a different plug,

Another solution is and 'On Board Glow Igniter', They amount to a rechargeable 'C' cell battery with a computer chip that you program to turn on at low speeds. This keeps the glow plug working when the fuel starts to pool in the top of the cylinder head which will allow you to have a nice reliable low idle.

I don't know the current price or supplier but it is worth looking into.

Good Luck.

bubbagates

My Feedback: (32)

Frst things I would want to know is this on grass or asphalt along with what the actual idle RPM is as displayed on a tach

If grass, then the idle is too high and I would look for the reason as was suggested.

If it's on asphalt, then maybe it is low enough and the prop pitch is to high along with a tad too much RPM or if the rpm is low enough then Ken's idea will work well

agexpert

My Feedback: (1)

RCKen,

It's a good idea to put a washer between the tubing and the wheel. Believe it or not, some fuel tubing will tear a big hole in your plastic wheel after a while. The metal washer seems to really help with this, (especially when fuel is added to the mix). The collar, however, needs to be that much tighter to get the stopping-power you need.

I do this 'brake-modification' on all of my planes and it really helps slow them down on landings too....makes taxiing easier...gives throttle authority on takeoff...just a good idea.

I have never flown from a grass runway...pavement is cheaper than irrigation here in CA.

Later,

Mark (NO!... the other Mark)

jeffk464

I always leave my glow plug starter on the engine while I taxi out to the runway, my engines never die at idle this way. Oh, remember to remove it before you take off

MikeRuth

Great suggestions, To answer of couple of the questions...
The Taxi and Runway is Asphalt(Sepulveda Basin, L.A. Ca.). I will get a tach reading next time out, But I had 2300 on the test stand. It's is tuned pretty lean and yes it is inverted.
I'm not opposed to on board glow ignitor with a sensor/switch for idel. I'll look into that.
The plug I run is an OS "F", currently brand new after breaking in on another plug. I never use break in plugs for flight duty. And since it is a new engine I'll mention that it has had 80% of a gallon run through it on the stand and now two flights on a 14oz tank.
The RPM on the engine only changes a very very small amount when the ignitor is removed.

The only reason I considerd adding some friction to the wheels is I'm fairly certain it is not going to idel much if any lower.

submikester

My Feedback: (6)

It may in fact be TOO lean on the low end. Do the pinch test; set the top end RPM of course first. Be sure that's just a few hundred RPM off of peak (use the Tach) and then bring it down to idle. Pinch the fuel line, if it runs up just a bit and then quits it's perfect. If it runs up a lot and takes a moment or two to quit it's too rich. If it just dies it's too lean, it will actually idle faster if it is too lean but it won't be reliable.

I fly at the basin as well and struggle with this on airplanes that have tanks that are too high. Where is your tank in relation to the carb? Ideally the centerline of the tank should be slightly LOWER than the centerline of the carb on an inverted engine. An upright engine can tolerate the tank a little higher.

my 2 cents worth at least...