Dale,

The Precision Eagle engines were manufactured by Don Kanak of Planes Plus. I have several and they are GREAT engines. Mine are all glow, no ignition. Make sure you have the velocity stack installed. This will aid in reducing the spit back out of the carb. If you have additional questions you should call Don (or Carla). Their number can be found on some of the banner ads on RCU.

Jim

Thank you for the contact information. So far the engine runs great, except for the top end RPM - which I may be able reach now with the new prop and some mixture adjustments. It idles beautifully, and pulls hard even at the lower RPM. I've got some time tomorrow, Saturday, to spend making mixture adjustments.

If this doesn't work, I may contact Don or Carla before buying the replacement carb parts that may not have aged well from sitting around dry for so many years. I expect these parts are rather cheap, and are probably worth replacing.

The Zinger prop made a big difference.

I don't have room for a traditional velocity stack, not without cutting holes in the cowling. Saw that all my 2-stroke engines from my yard (Stihl engines) ran well with filters on the carbs. So I made my own carb filter/foam velocity stack using some Briggs and Stratten carb filter material - works great. Adding this piece does not affect RPMs - the side facing the prop is open, so I'm getting a bit of ducted air intact effect.

Dale

Yes, of course! I have access to a couple great lawn/yard supply companies that handle most of the major brands of 2-stroke powered equipment.

This one is a Walbro - company name is stamped into it. I have time this Saturday to work with the mixture adjustments - but I may just get the replacement parts anyway - they sat unused, dry so long that now I'm not comfortable taking it up. Would hate to lose the plane because I was to cheap.

Have attached a picture that I took a few weeks ago.

DaleCS:

Coupla Things:

1) What exactly is that prop adaptor you got from C&H ? Can you tell me a Part #??

I'm very interested 'cause I'm slowly finishing a Byron Zero I bought 12 years ago with a Prec. Eagle 4.2. RC Ignition put an electronic synchrospark on it, but of the two Byron 3-blade props I've got, one is irreparably off-center and the other doesn't turn good rpm. I think those Byron props were nice scale "lookers" but are not well-matched to the 4.2. Now, unfortunately, I've got my ignition magnets set in them.

2) Although this is my first Byron, I have a lot of experience with large warbird gassers, and I can address some of your concerns. I assume the Hellcat, like the Zero is in the 85-90" WS category. If so: A) you need to use a prop that'll get you close to 7,000 rpm, even if it looks small against the cowl. If not, the mathematics of a 10" pitch is not going to give you enough airspeed. If the 4.2 is close to the G-62, a 22X10 should be about right. B) 30 pounds is not too heavy, and 56 oz/ft wing loading doesn't go on the same worry scale as smaller planes with less wing chord and volume, wherein 30 oz+ would be worrisome.

Please keep us posted here with pictures, and Good Luck.

Maybe we can dog-fight someday at a meet. Be a real crowd-pleaser (if you win).


mt

In response to your two points:

1) I can't give you an exact part number for the adapter, and if I could you really shouldn't use the number anyways. The guys at CH know all about the Precision Eagle 4.2, and that it was built over the years with different drive shafts, with different tapers.

Before calling them, measure the diameter of the shaft right behind the threads, then again as far back as you can. With these measurements alone, and mentioning that the adapter you want is for a 4.2 they'll be able to suit you up.

If you send CH your engine, they'll pick the right adapater, determine where the magnet needs to be insert, drill/ream the magnet hole and install the magnet. They'll even tune th engine for you - but you made need to retune it when it comes back due to altitude differences. Their located in Wyoming - so they may be higher or lower then where you're located.

I located my own magnet hole and did the drilling/reaming myself - no problem if you have drill press and place to buy reamers from.

CH was very helpful - you'll do fine with them. Oh, they'll send you a magnet too, so no need to worry about the ones buried in your other adapters.

Have been told by a number of people that the Byron props will fly the plane - very 'scale like.' I'd rather have the extra power available to me if I need it, and if I then want to make take-offs very 'scale like,' I'll just throttle back the engine.

I rarely run anything a full throttle for very long, but its nice to know you've got extra power available if/when I need it.


2) Its an 87 inch wing span. 4.2 cubic inches works out to 68.8 ccs. The G62 is listed as a 3.8 cubic inch engine. Have had recommendations to go smaller, and some have said the 4.2 should be hitting 6200-6400 RPM with no problem.

I have tried a 22x10 and have gotten 7K out of it. And, I will certainly consider it for at least the first flights. However, my main concern is that I have not been able to get rated RPM of out of the engine for the props spec'd in the manual. A number of others have agreed that the spec should be achievable, unless something is wrong. I'd like to hit the specs by finding out what is wrong and fixing it before flying.

Today, I decided to tear the carb apart to check the gaskets, diaphragms, filters, etc. Found a bit of dirt, but not enough to be worrisome. I also noted that one of the diaphragms has a metal plate with a pin on it that is supposed to be inserted into a spring loaded lever within the carb. Now in taking it apart, I did not notice whether this pin/lever had been assembled properly or not.

So, I put it back together, correctly, and tried it again - I gained another 300 RPM, now hitting 5800-5900 and sometimes peaks of 6000 RPM. Between this fix and the Zinger prop, I've gained 900 RPM.

My carb is Walbro WJ1D C-4. I want to get a carb kit for it so that I can compare the condition of new diaphragms with those in my carb - mine feel a bit more papery than I expected, but then I don't have a benchmark to compare them against.

I had the carb off once before, but had never disassembled it, and it had always been running several hundred RPM low - so I must assume that the carb had been misassembled somewhere in the manufacturing/pre-ownership pipeline before I bought it. It always ran great at idle/low/mid-range. Transitions and high range were fine, too, just not high enough.

I don't know the function of that spring loaded lever that the diaphragm attaches to. However, I recall reading something about the function on website dedicated to carb maintenance on Ultralight Aircraft engines. There are some adjustments that can be made - will have to find this site again. I expect this lever helps keep the diaphragm pumping action in sync with the engine - it appears to keep sync fine at lower RPMs no problem, but needs an assist at high RPMs.

Changing the spring setting must have something to do with changing how far the diaphragm moves for a given pressure differential - not something I'm going to change without learning more, first. I expect that if the needle valves were ineffective, then there might be a problem with this diaphragm not moving enough or moving too much due to a spring problem.

Must run. Sorry, must fly! Here's some more pictures:

The gasket goes on top of the carb, and the diaphragm on top of the gasket..The lever opens the inlet needle to let gas into the carb...The end of the lever with the fork should be set level with the casting next to it..It is not an adjustment having anything to do with pressure, it works from atmospheric pressure on the diaphragm...The first AT6 racers at Madera using G62s running 22-10 Zingers at 7000 rpm flew about 95 mph.....Radar clocked...Theory is good, radar is absolute...Ask the last cop that gave you a ticket ...

Thank you - will check the height.

One more thing regarding the prop adapter: CH will ask if you want a single or multi-bolt hold down for the prop. The single has a shaft that runs through the center of your prop. It also has a threaded ID which you can use to hold your Byron spinner in place. It also comes with a large prop nut washer. I had some guys in our prototype shop cut a groove in this washer that matched the dimensions of the spinner provided by Byron. So, the bolt through the center of spinned threads into the adapter and the back of the spinner sits in the groove cut in the prop washer.

I don't have a picture of this setup - can get one if you'd find it helpful.

Dale

Will likely run with the smaller diameter prop, too, once I understand why its not performing to spec. I've got most of the problem solved - would like to finish it. I expect that there is a trade off between speed, rate of climb and acceleration when switching between prop diameters. If the 24x10 is overloading the engine, then perhaps all three measures would improve with a smaller prop.

DaleCS

I had and I said a Byron Hellcat with your set up, you can see it in the last Warbirds over Delaware video, Plane was 26lbs, running on the 4.2 Sachs, which Ralph at RC ingnitions got running again after my crash[o:] at warbirds over IN, back to the bird, I got rid of the purrpower put a J&A pits style muffler, turning a 24x10 Menz S at 6300 RPM on the ground. using 50:1 Stihl oil mix. Velocity stack on the carb.

This plane was a hot rod , could keep up with the best of them at warbirds show, even a bit too fast for some pilots I was flying with in formation.

I'll be happy to answer any questions you might have.

Popierre

Does anybody know where to get a cylinder gasket for a Precision Eagle 4.2 engine???

Thanks,
Joe at

Dale

you have the patience of Jobe.

I have now read the whole thread and cant wait for your flight reports. Please keep us advised

Cheers

Phil

Anyone who sells a 4.2 engine..Brison, Fox, J&A, Air Hobbies, etc..Same cylinder...
Easy enough to make one..You can get a small piece of gasket paper from an auto supply store...Nothing special about the gasket....Take the gasket paper, lay it on the bottom of the cylinder, gently tap around the bore and outside of the base with a small ball pein hammer..Takes about 2 minutes...

popierre and I have had several ideas regarding Precision Eagle 4.2 engines from Bryon. I was able to make significant improvement by:

- using higher octane fuel
- using synthetic oil at 100:1 mix ratio
- switching to ProZinger series props
- finding a build error in the carb

However, the last, big change was provided by popierre - he suggested dumping the PurrPower muffler and replacing it with a Pitts style from JA Engineering.

What a difference - gained 300-400 RPM, and the engine operating temp has dropped dramatically. After running with the PurrPower, I could fry an egg on the crankcase. Now, I can touch the JA Pitts muffler immediately after running, without pain, and the crankcase and head temps can be described as 'warm to the touch.'

I'm now running 6.2K -6.3K with the ProZinger 24x10. This is spec in the Bryon materials for a Zinger 24x10 - I don't know how they could have gotten there running natural oil, low octane and a PurrPower muffler.

This plane will fly, this year, finally.

Thank you, to all those that contributed, especially, popierre.

The PurrPower muffler does create a nice sound, but its better used as just an engine mount - cut the header off to make room for a JA Engineering Pitts muffler, you'll be glad you did.

DaleCS

Must be something about the air in Arizona, my engines run the same on plain old 87 octane regular and Pennzoil 2 stroke as they do on 100LL and 100-1 Amsoil....
The restricted muffler DOES slow the engine down....

RCIGN1's point is well taken - I've not run the engine on 87 octane, non-syn oil since installing the new muffler.

With the engine now running on the new muffler at higher RPMs and running much cooler, perhaps the higher octane/syn-oil is not a significant factor, now.

Worth a retest, but it will have to wait - I need to complete a few clearance issues with the newly installed 4-40 hardware, airbrush out some hanger rash and recheck balance. I have confidence in the engine now, and need to fly it this year - everyone has started to think it will never fly!

Website for J-A Engineer is: http://www.j-aengineering.com

It flies!

Was a bit of a scorcher Sunday at 91 degrees F. and high humidty, little wind. But with some help from veteran warbird pilots from the Plymouth-Canton Flying Pilgrims, my Hellcat finally left the ground - twice, and returned to the ground safely - twice!

Thanks for all those that offered guidance on this subject - I used much of it. Thanks to your help, I now own an RC warbird aircraft - not just a model! Models sit on shelves, aircraft fly.

I have a Byron P-47 with a Precision Eagle engine, Purr-Power, and a 4-blade prop. I have had this plane built, maintained, and ready to fly for 12 years (seems like I always put it off another year). Have you or anyone ever flown the P-47 with this set-up? Have you flown your Hellcat with the 3-blade set up yet? I take it from the latest threads that you are now using a 2-blade system with a completely different muffler system too. I've never started the engine because I don't want it sitting extensively with fuel in the carb if I'm not going to fly it that year.

I also have a Byron P-40, Hellcat, and Corsair (kits) that I will be building (I plan on building one a year, starting with the Corsair in September) and using the Sachs/Precision Eagle 3-blade set up. Would you suggest that I build them using the 2-blade system instead, right from the beginnning? I so love the look of that big prop on the front!

Right now I am trying to work the kinks out of my Byron P-51 with the Prop Reduction drive on it. I have been running the system extensively on a test stand until I can get serveral reliable runs at 100% power settings (no component failures) before putting it in my plane . Do you are anyone have any experience with this set-up? I bought the Prop Reduction used and completely rebuilt the unit but I have had a couple of bearing failures. I think I've got that ironed out now and will be installing the system in my P-51. I'm getting 3,000 rmp out of the 4-blade prop at 100% power using the reduction system and a Q-35. I believe that is about normal with the Q-35. Any feedback?

Bob

I've have no information regarding the Byron P-47, nor do I know anyone that has.

I have not flown the Hellcat with the Bryon 3-blade setup, yet. I have been told that this prop works very well, giving the airplane a more scale-like take-off. I take this to mean "slower." I've also been told by former Byron personnel that the blades are very durable - in fact I recall now that before they shut down, Byron actually ran a P-47 with a 4-blade prop up to take off speed and then pushed down elevator, driving the prop into pavement. The result was a prop that was still 'flyable' - one could probably safely take off and get the plane back down, but the damaged blades should still be replace for safety's sake (so I'm told, and I would certainly replace the blades, too).

I understand that Iron Bay, the company that purchased the Byron tooling is selling replacement blades. They are also supposed to have adapters for mounting other props. When I called, they had none in stock, so I went to CH Ignition and they supplied me with a fine adapter.

These prop adapters don't affect the position of the prop relative to the cowling - so you can build the aircraft/mount the engine without caring whether you will run the Byron prop or something else. All other prop/adapter combinations are likely to be significantly lighter than the Byron setup - so you may want to consider nose ballast that can be increased/decreased depending on the setup you are running. This is probably less of an issue with the Hellcat and Corsair, as the gear rotates/folds back - you will always be more nose heavy with the Bryon prop if you don't remove some of your ballast, but the effect will be less noticeable on these aircraft.

I ran a ProZinger 24x10 with a J&A Engineer Pitts-style muffler - this was the only way that I could get the engine to run at Byron's specs. A 24" prop is close to scale on the Hellcat, but leaves very little ground clearance when the tail lifts on take off. I put a quarter-inch of rod stock at the top of each retract strut as a spacer (remove strut/spring, insert spacer, replace strut/spring) in order give a bit more preload on the springs - this helps keep the prop from hitting ground, as the robart struts were a bit soft for a 30 lb plane.

I've just purchased a Mezjlik 22x10 3-blade carbon fiber prop. Its installed, but haven't flown it yet, nor I have I run it to get RPM readings. It does look a little small, as its more fitting for a 1/7 scale Hellcat - but it does clear the ground well and its light as a feather. For the 4.2 engine, the Byron props are a bit oversized - using 2-blade vs. 3-blade comparison calculators, I believe the engine is 50% underpowered for the Byron 3-blade prop.

It may work fine, but its really overloading the engine and not providing any safety margin in the event that one needs to get the plane moving fast, immediately. I may fly with it, but not until I'm very comfortable with the performance of both the plane and pilot (me!). I'd rather get all the power I can out of the engine and throttle back, rather than be limited.

Don't use the PurrPower muffler at all. Besides the RPM loss, the higher restriction it places on the engine cause it to run very hot (it will melt that dummy engine cover supplied by Byron) and you may see the engine actually spit fuel out of the carb - its all supposed to go into the engine, so this is definately a power robber.

If you've not mounted the engine yet using the PurrPower muffler - DON'T. I think there are better ways to mount the engine (e.g. an engine mount box - which will require you to replace the one-third firewall with a full firewall, but it the mounting box will give you a nice place to store that nose weight!) and perhaps the PurrPower muffler can be saved for another engine that it would work fine with. It the PurrPower is already installed, you'll probably just want to leave it in and cut the header off.

The engiine will definately sound more like a chainsaw engine with a more 'normal' muffler on it. The PurrPower does sound very nice - but the performance/safety cost isn't worth it.

Since your planes are a bit old, they probably all came with 2-56 hardware. Throw it out! You should not trust the plastic after 10-12 years of aging and IMAC requires 4-40 hardware on all birds of this size. If you've already got your P-47 built with 2-56 - tough. Change it to 4-40. I had to do this on my Hellcat - its well worth it.

Also, trash the flap/servo linkage setup - its way to sloppy. Use two servos as close to the inboard flaps as possible. I mounted mine in the ply inboard wing ribs such that the servo arm moves in a plane parallel with the fuselage. This works well, and allows you to connect the linkages to the flaps as Byron intended. However, this method is still a bit sloppier than it could be, as in the fully deployed position, the linkage is not in a good position to maintain downward force on the flap. A better method involves mounting the servo such that the servo arm extends out the bottom of the inboard wing panel and then connects to a control arm mounted to the underside of the flap - in this manner, the servo pulls on the control arm in the same manner as the ailerons, giving a much more solid connection. The servo arm, linkage and control rod aren't hidden anymore, but neither are any of the linkages/rods associated with the rudder/elevator/ailerons - so what's a couple more going to do to the appearance?

Also, the Byron kits did not come with adequate fuel filters - put filters on both the fuel fill line (or on the pickup in the tank) and the vent line. I have a sintered filter in the tank pickup and an in-line filter on the vent line, and the fill line is capped after fueling. As the engine sucks fuel from the tank, air enters from the vent line - this line can suck up quite a bit of debris, especially if you've hidden the venting outlet somewhere under the belly of the plane or the underside of an inboard wing panel - the prop throws up a lot junk from the ground.

I have no experience with the Q-35 or reduction unit.

If you want to make the canopy slide, I found some real nice "canopy rail" stock from Balsa USA.

Oh, and one more thing - from numerous sources I've been warned to replace the Byron wheels - the tires tend to separate from the plastic hubs if you get the aircraft going a bit sideways on landing. I'm using some aluminum hub wheels from Robart - these are designed to capture the tires in a couple different places (near the hub and out towards the rim) so they are much more secure.

Much of what I'm stating here has been lessons I've learned from others, which I have confirmed in my own usage. If I'm starting to sound like I know what I'm doing, its because I've listened well.

12 years is long enough - get 'em flying, eh!

Cripes - I've written a novel. Hope you find some of it useful. Feel free to contact me again.

Hi DaleCS,

I have just picked up my Goldberg 30% Ultimate from the gentleman that assembled it for me. It also has the Precision Eagle 4.2 as does your warbird. My plane comes in at 22 3/4 lbs. and I am using an APC 22x10 prop for the first flights.

I started the motor in my garage last night, man, talk about power!! One thing I noticed is that you definately need to use the choke. Two or three flips with the choke on and ignition off, turn the ignition on and she fires on the first or second flip.

Maiden is today!!!!!

Ken

Hi, Ken

Have been offline for awhile and not into my home email box for some time, too. So, I just got your message.

Hope your maiden flight went well. At 22-23 lbs, that thing should scream with that engine. I'm currently running a Mejzlik 22x10 3-blade prop. 24 is closer to scale, but leaves little ground clearance; and, the 4.2 really doesn't have enough power to swing a 3-blade 24x10. A 2-blade 24x10, yes, but not a 3-blade.

Would like to hear how your flights went. I've only got 5 on my Hellcat, 3 with me doing the flying - loops and rolls - no landings or takeoffs yet. This is my first big, heavy scale fighter (i.e. expensive) airplane. Though I've flown for many years, this is a whole new class of airplane and I really don't like taking stuff home in bags!

One hint: Leave the ignition on while the choke is on. Once the engine coughs, turn the choke off - it should start in the next flip or two. You're not having any problems starting the engine, so this hint may not be two helpful. I have noticed some variation in the number of flips it takes to get the fuel to the carb, especially on really cold days.

Dale

Hey Dale,

The maiden went great! I had about a dozen flights on it before the catastrophe. I was over the trees, at the west end of the field, in an inverted harrier, and a combo if not enough power, too much elevator and 10 to 15 mph winds and I allowed it to stall and go into the trees.[]

I have the pics under "30% Ultimate Crash!!" in the crash forum, not pretty.

But it's all good!!! I'll be flying a Wildhare 28% Extra Special next year!!

Ken

Hi Dale,

If you have any questions about Precision Eagle or Walker gasoline engies contact Carla at Planes Plus. They are the former owners of Precision Eagle and Walker engines. She has parts for Walker engines for sure because I asked, she might aslo have parts for Precison Eagle as well. She used to machine the engines herself.
http://www.planesplus.com/

Skylark

Maybe...How come they look exactly like Husky Challenger engines ? Coincidence ?
Maybe she worked for Russ Stoltz ?
His company makes the Challengers, some of the finest CHAINSAW derived engines ever...
Eagles (and Eaglets, Walkers, and A&M etc) are Sachs, Challengers are Husqvarna...

Hi Dale,

You can get a velocity stack at B&B Spectiaties they call it a Power Ram $8.95: http://www.bennettbuilt.com/page2.htm
Also if you have questions on Precision Eagle was owned by Carla at PlanesPlus.com.


Skylark