PAW .19

[david beazley]

I recently purchased a single ball bearing PAW .19 diesel from Eric Clutton and have been breaking in on the bench.  Any suggestions as to what  would be a good plane to put it on?  I guess I should have thought about that prior to purchase.  I have never had a diesel and wanted to try one.  I understand you can run a larger prop than comparable glow engine, but am unsure as to what would be a good airframe for this engine.
Suggestions?

[Robert Zambelli]

I had a plain bearing PAW 19 in my Nobler for a while and it flew quite well.
I DID NOT (and would not) purchase it from clutton.

I picked it up at a swap meet for around $20.00 (new).
It was easy to start and set, ran very well for around twenty flights and then the lower end of the con-rod wore out.
I can't remember if the fuel came from clutton or davis but it was mixed exactly per instructions.

Bob Z.

[Steve Thomas]

It'd do well in something like a Ringmaster or Shark 402 (diesels seem to like being side-mounted). I've got one in a KK Spectre, which looks nice and is a great flier for something that size.

[Dennis Toth]

Steve,
Depending on what event (if any) that you intend to fly. Basically, anything that a muffled Fox 35 will pull the PAW 19 will pull. For me that's about 46" - 48" max span. Don't over prop it, 9x6 RSM or BY&O would be pretty good flight prop. I flew one on a Ringmaster in OTS at the KOI a few years back and placed 2nd.

Best,   DennisT

[david beazley]

I have a Black Hawk Giant Stuntmaster kit under the bench, would that work?  If so I'll move it up in the rotation.
http://www.bjm-home.com/BJMEnterprises/product197.html

[Chris Wilson]

  Any suggestions as to what  would be a good plane to put it on? 

I had one in a Mercury Monarch as a young boy and it flew just fine, invert mount and all (if you consider the 'gear change' moment with inside maneuvers acceptable that is.)

42" span and no muffler. Later I used the old ring muffler with it and it killed off  lot of the performance.

The newer side canister muffler might add some weight to be factored in if you are considering older designs though and If I was to build this model again with a PAW 19 I would move the engine back about 1" along the bearers.

http://www.model-plans.co.uk/mercury.htm

[John Park]

Many moons ago, I built a Spectre from the KeilKraft kit, with a single ball-race PAW .19.  Sadly, I used the kit tank, which made the engine cut dead in the squares, and the kit solid leadouts, which I blame for a heart-stopping series of binding lines (they never gave that trouble with my other models, all of which had flexible leadouts).  It was hopeless, and I soon gave up on it: but I've still got the kit plan, and if I can ever get round to it I'll build another with all the usual modern features - adjustable leadout guides, tip weight box etc.  However, for out-and-out fun with PAW diesels (2.49 and .19) I don't think you can better GMA's English Peacemaker, the 36 1/2" span model he designed for AeroModeller.  It really is the greatest.

Regards
John

[Motorman]

Check the manual for prop suggestions. Those engines have zero weight relief in the piston and zero counter weight on the crank. They depend on running a certain rpm range to not vibrate. Break in fuel has 1/3 oil yes, 33% castor. Diesels don't swing bigger props because they make more power. They make less power than a glow but peak power is at a lower rpm because of low timing.


MM

[Chris Wilson]

They make less power than a glow but peak power is at a lower rpm because of low timing.

Not sure about the validity of the above, and 'what' glow' are you referring to?
Some facts are -

- the same PAW diesel converted to glow use has less power than the diesel version.
- (the only other example of this I can dig up at a moments notice is) the Marz diesel - same conclusion.
- and a tuned PAW make tremendous power.

So its not about the timing if you are comparing the SAME engine.

Lets see how using the same engine in a more modern guise shapes up with Davis type conversions.

- They all seem to make comparable power if you don't fall back onto resonant exhaust systems and add vitamin N to the glow fuel.

And lastly lets look a more modern take and compare the purpose built Parra glow and diesel engine -

- they perform very similarly in terms of power.
- and the diesel does not like a large prop at all.
(And speed diesels simply love to rev!)

The issue with ye olde PAW is that the design is not current best practice and using it as a term of reference is going to be horribly flawed in a modern argument.

They work well for what they are and they are locked in time, so its best enjoyed and left at that.

Cheers.

[Chris Brainard]

I've got both the plain bearing and double ball bearing P.A.W. .19's. Both run well. I used a BY & O 10 x 5 prop. I flew these on a Goldberg Shoestring and a Charles Mackey ProFile. Both flew easily at our almost 6000 ft elevation.
Chris

[John Park]

My standard prop. choice has always been 8x6 for the 2.49 and 9x6 for the .19 (currently Master Airscrew in each case).  Tank-wise, PAWs are OK with a conventional metal stunt tank - which must be Uniflo - but if you have the patience and skill with a soldering-iron, a chicken-hopper tank is even better.  One final point PAWs do seem to be happiest sidewinder-mounted.  Upright or inverted, they can sometimes suffer from a 'Fox burp' in hard corners, which is why PAW's own Tony Eifflaender switched to a sidewinder arrangement for his Freebird 4.

Regards
John

[Motorman]

That's why all the speed records are set by diesels I guess.

[Andrew Tinsley]

For speed and range in racing events, find me a glow engine that will beat a diesel.

Andrew.

[Steve Helmick]

Jeez, the guy just wants some advise about airplane size, but y'all had to start a pissing match. WAY TO GO! NOT....

My advise is to get it well run-in on the bench (which I hate doing), because diesels don't like running rich when you go to fly them. I found the sound for the NV setting to be pretty subtle, compared to glows. Or maybe I'm deefer than I thought I was.   

A real kit Flite Streak (not an ARF) (or that Stunt Master) would be a great place to start.  Steve

[Andrew Tinsley]

Quite right Steve, I should not have took the bait. So my apologies all round.
     I like PAW engines, but they are not really state of the art by a long way. I have always found the plain bearing PAW 19 to be less powerful than expected. So maybe a Flightstreak is a good start.
     I would even suggest that the Peacemaker would be a better option. GA designed this one for Aeromodeller magazine and it used an Oliver Tiger 2.5 cc diesel. The Peacemaker is a reduced dimension Flightstreak. It should be perfect  for a  plain bearing PAW 19.
     I would also use some ply doublers that go back to the at least the wing LE I cannot remember if this is on the plan. You can download the plan from Outerzone, the one I am talking of is the 36" span profile, they show 4 variants!

Regards,

Andrew. 

[bob whitney]

  should probably leave this alone but too many loose ends , when comparing glow's to diesels ,it needs to be top of the line diesels  2.5 or smaller
  in goodyear where there is an unlimited tank no chance, in clown where the glow's need to be restricted to get some distance ,the diesel has a chance , a glow can get from 40 to 50 laps at over 100 mph. the diesel can go over 100 laps . the problem is getting the diesel in the air at that setting which can be done with a rich start. the next thing is getting the diesel to do the 100 laps without getting too hot
  i ran a Nelson 19 converted to diesel for a while and did pretty good till i ran out of parts . a $600 F2C 2.5 diesel could be set up for clown and do well..in F@C they use a pressurized filler with two to 3 diff mix's to get through 100 laps at top speed.
  i converted a norvel 15 to diesel and put it on an ARF flight Streak and it was one of the most fun planes i have flown----Until the wrist pin pulled out of the piston and this was with a 9 in prop. .i converted a S/T 35 to diesel and put it on a mod Ringmaster with a wide blade 10/6 and it flew great Until it pulled the wrist pin out of the piston in about 20 flights .i am beginning to think it isn't worth the trouble ,but it is fun
  i had a crank break in a PAW 35, sounds like i am hard on engines. keep plenty of oil in the PAL and it and a good size prop and it should fly great,was i using enough oil?? no one wanted to pick it up after the flight
 if u want to watch a TD .049 melt before your eyes
,put a diesel head on it with a speed prop on it and watch it melt. with all this i still want to use a diesel in OTS to get the extea 5 points