Poulan with Header/Muffler
 

Hello guys; Here is a pic of my Poulan 46 with a Muffler a fellow modeler friend of mine designed for his IMAC plane with a BME 102. I was getting ready to run the Poulan so I thought "why not" I had welded up several for my friend and had a couple extras laying around so I made up a header and fired it up :cool:
With the open header I was getting 6800 with a Zinger 20X10 and 95 db at ~25 feet. Very loud but a sound any motor head would appreciate :D

With the muffler installed the RPM was 6300 with the 20X10 and the sound was 85 db @ 25 feet. Very nice and at about half throttle the prop noise was louder than the engine.

These were the first runs on the engine and I was pretty impressed with it other than I could not start it by hand flipping?? I could rope start it just fine so I dont know if something minor is keeping it from firing at the lower cranking speeds or is it just the nature of the Poulan??

I need to get an airframe for this motor now. Im going to try and change a few things and make up a muffler that I can firewall mount and run the header down to it.
Adam

Poulan with Header/Muffler
 

very cool! nice job. Im assuming thats aluminum? Did you make the header? how did you get the nice bend?

bent aluminium
 

i've got a collection of old alum lawn chairs, all kinds of nice bends in 3/4 7/8 and 1" tubing, a lifetime supply of headers for real cheap. :D

Poulan with Header/Muffler
 

I use a JD2 bender to bend my tubing. The header in the pic is .049 6061 aluminum 7/8 dia. The muffler is 3" dia and 12" long. Im going to try some smaller mufflers with less baffling and see how far I can go before it gets to loud.

Zagnut; Your stuff sounds good if the material is any good. There are a few alloys of aluminum that cannot be welded or dont hold up very well to heat or vibration.
But if I had it I sure would try it too. Its hard to beat free ;)
Adam

Poulan with Header/Muffler
 

Adam, that muffler setup looks great. I wonder if you could possibly "tune" the header pipe length to gain top end RPM.

These magneto ignitions do need to be flipped at a fairly fast rate to fire a decent spark. You might try closing the coil pickup gaps a little.

Re: Poulan with Header/Muffler
 

Depends what magneto module it has. I have read a few times that the PHELON magneto modules do not make a very hot spark. My Poulan 25cc (1st conversion attempt) has the Phelon module, and after MANY attempts (~50 flips?), I was able to start it by hand. Once it warmed up, it started with 1 or 2 flips.

Poulan with Header/Muffler
 

Well I tightened up the flywheel gap today down to .010. Im not sure what the spec is on the Poulan 46??
Anyway I got a couple pops but it still wouldnt start. When using the rope it fires right up. Im wondering if my fuel isnt fresh enough and has lost a little of its volatility (sp??) and needs a hotter spark to fire off??
The next time I run it Im going to mix up a fresh gallon and see if that helps.
Volfy; I plan on trying some different lengths. Just waiting on some more tubing to arrive.
Adam

Poulan with Header/Muffler
 

I set my gap using a business card. It's a real tight fit, but probably not less than 0.010

Sounds like you have to get the flip speed faster somehow... If the rope trick works, why mess with it.

Poulan with Header/Muffler
 

Yea the rope works nice for now, as long as everything is clamped down to my picnic table. I cant imagine yanking on the rope when the motor is on a plane :stupid:

Seriously; The rope works great for bench running but something else will need to be done so it can be flipped or get a big electric starter.
Has anyone used one if the recoil starters on a Poulan?? I havent cut the stub shaft off the back of mine yet. I had one on a Quadra years ago, just a one way bearing and a big spring.
Adam

Poulan with Header/Muffler
 

I hate to do it, but I'm gonna buy a stronger starter. My old one isn't strong enough. Untill now, the biggest engine I've had to worry about was my friend's .61 Webra.

Poulan with Header/Muffler
 

instead of a big starter ($$$) and heavy batteriies why not buy an electronic ignition? extra sensors are cheap and allow you to easily move the ignition from plane to plane so it doesn't have to be more expensive.

dave

Poulan with Header/Muffler
 

I agree Dave; I think the only way I would go for one of the larger starters is if I came across a fantastic deal. It wouldnt take much more for me to go for the ignition. Ive been looking over suitable airplanes right now and playing with the exaust systems.
Adam

Poulan with Header/Muffler
 

This is my first conversion attempt, and a primary factor in the design of the entire plane is to keep costs low.

Gutterpipe fuselage
Coroplast wing
Homemade landing gear
WeedEater® engine
home-made muffler (eventually - still in progress)

Over 95% of this plane was purchased from the NEW LHS (Local Hardware Store). Only the fuel tanks, Tygon and radio equipment is through normal RC sources.

When I do another, I'll probably do electronic ignition. I have to learn to crawl before I start running. Anyone got plans for a homemade electronic ignition system? :D

Poulan with Header/Muffler
 

Hey Id like to see a pic of that plane;

Id like to see plans for a electronic ignition. Anyone tear apart their C&H so they could "reverse engineer" a replica??? :rolleyes:
Adam

Poulan with Header/Muffler
 

CH sells their circuit board and coils for pretty cheap if you want to DIY. the box,cable, and boot can be found in any respectable junk box and the sensor is about a dollar from electronics suppliers.

dave

Poulan with Header/Muffler
 

The plane's not done yet, but thanks to Adam's prompting, I have posted preliminary pics in my gallery It's quite a departure from my previous project, a SlowPoke 25. :D

http://www.rcuniverse.com/gallery/da...on01-thumb.jpg http://www.rcuniverse.com/gallery/da...on02-thumb.jpg http://www.rcuniverse.com/gallery/da...on03-thumb.jpg http://www.rcuniverse.com/gallery/da...Poke-thumb.jpg

8 foot wing span + 17 inch chord = 1632 sq-in wing (I hope it's not to big)
Current all-up weight (all un-installed parts included) = 10.0 Lbs
Therefore, Wing loading = 14.12 oz / sq-ft

If it flies like I hope, I hope to use it as a trainer (big=easy to see, gas=cheap, 16oz fuel = long flight)

Poulan with Header/Muffler
 

love that airfoil :cool:

Poulan with Header/Muffler
 

Dave Ill have to call C&H. I had a little sticker shock when I first looked at their conversion kit for the 46 Poulan. I dont need the carb mount; prop adapter or other stuff and the price on just the ignition isnt to bad.

Dennis; the Spad is pretty cool, did you go for the yardstick for a spar or something else?? Ive got one of those 25's I think I got it out of a Craftsman weed trimmer. Ive done most of the conversion but havent ran it yet.


Adam

Poulan with Header/Muffler
 

For my sake, I hope you're serious Zagnut, but I'll understand if it was said in sarcasm.

Poulan with Header/Muffler
 

Adam - I was concerned that yard-sticks might snap during a pull-out from a dive. Instead, I used Coroplast on edge, several layers (4 in the center, tapering in layers towards the tips). If the stress gets to much, the spar can flex somewhat. To further reduce the chance of "snap" manouvers, I used the slow 100oz-in GWS servos (0.33s transit for 60º) for everything but the throttle.

What's your opinion - will it fly? Is a 25cc Poulan enough?

P.S. I added some specs to my earlier post with the pics.

Poulan with Header/Muffler
 

Try a PBF; Now there is an airfoil :stupid:

Poulan with Header/Muffler
 

What size PBF would be appropriate for a 25cc Poulan? The local surplus center has several of these referbished engines (without trimmer parts) for $60 CAD ($42 USD).

Poulan with Header/Muffler
 

I dont know; Ive heard some others talking about making a PBF for the Ryobi 31cc to see if they could get it to hover.

I would like to watch that :spinnyeye

Adam

Poulan with Header/Muffler
 

Egads! The Canadians have gotten a hold of our stealth technology!

Anyway, I've heard it said that as long as you got a good motor pulling up front, you can fly with an airfoil shaped with your wife's high heels.

Poulan 25cc
 

Volfy - you seem pretty knowledgable about these conversions. How many HP can I expect from a 25cc? The LHS suggested (and sold) a 15X8 Master Airscrew for break-in. What should I use afterwards? What kind of RPM's can I expect? Do you think my "Blue Heron" will fly?

Poulan with Header/Muffler
 

you should see my "french curve special" airfoils!


at 8 feet and only 10 pounds that plane should be a nice slow relaxing floater but you might have trouble with the sharp LE.

dave

Poulan with Header/Muffler
 

use something like a 16x6 as you need all the thrust you can get. don't use a master airscrew though, you dont have any spare power to waste on inefficient props

dave

Strato!!
 

Strato....Dude, you gotta get video on the maiden flight of that thing....Great job!!

I'm working a "rail-type" spad along the same lines..using 6 ft furring strips 3/4x1 1/2. Two for the fuse, one for the spar...
In my 'gallery' here on RCU.

How did you work the wing mounting issue? I don't want to use #64 rubber bands on a giant plane...

Close ups of the engine installation too!! If you can get them...

Great Job!! Looks like a Sunday fun flyer to me!!!

CrazyHerb

Poulan with Header/Muffler
 

Thanks for the support. I've kept it pretty quiet about this plane, 'cause I'm really taking my time with it. I had hoped to have it ready by now, but alas, not yet. I don't know any local SPAD builders (I know we have some), so I'm probably re-inventing the wheel. It doesn't help that I don't have a building area in my new house yet. For the wing wiring, I made a custom plug using a computer DB9 connector to connect all 4 servos at once with no chance of error. Within the connector, I have all the power and all the ground wires connected together too. I haven't quite decided how I'll mount the wing. It's not to heavy, and since I hope to use it for training, I'll probably use elastics.

This project is filled with personal firsts:

• First SPAD
• First "Giant scale"
• First gasoline conversion
• First dual tank setup
• First home-made muffler
• First computer radio - the new Tracker II & Seeker II receiver (so it can be flown on any channel)

I'll see what I can do for video - I don't have the equipment for digital video, just pics.

First time for everything..
 

So Far looks like your doing great!!

I've build/Flown .40 sized SPADS.
I've built/flown giant scale.
I've never ran dual tanks (other than one for gas and one for smoke).
I tried home made mufflers and gave up...they all rattled apart.
(However, I have an awseome point of contact though for TOP QUALITY mufflers for around $25 plus shipping).
I used to fly Hitec Spectra module Prism 7 with several different Rx's.

And get this.... I've used a DB 15 connector for a 4 servo wing in my old ultrastick 1.20...hehehe...worked great...but was a PAIN to solder...then dipped in silicone sheath.

Don't ask for pics of the DB15 connector...I wiped out the plane on maiden....(reversed ailerons)...I was so upset with myself I almost quit the hobby...it was the second time in 3 months...both maiden flights...other was a TopCap....

Just keep using those ideas that come up in the SPAD forums and spadworld.net under bigguns....there's a lot of good info out there from those who HAVE done it...

And YES.... I WILL GET MY RYOBI TO HOVER.....
someday!!

Also, definitly know how time goes....try a 5 month old baby...phew...biggest time consumer...then second home based business...and active duty military career to balance...along with keeping a fully functional relationship with my lovely wife. Bless her sole for her paitence with my hobbies and my poor time management skills....oh...and getting tagged with being Vice Pres, Secretary, and webmaster for our club...

Just keep us posted....I'll try the same....
I have my first wing half folded and my cutting board engine mount done....now for 3 more hours......just...got ...to get ....arg...the time....hehehe... :D

Best of luck!
CrazyHerb

Re: First time for everything..
 

I've never even seen those forums. I've been to www.spadtothebone.com often though.

Way back in 1990, I came across someone (on the Internet) who had designed what is now called SPAD. They were selling the plans on 'the Net', and I refused to pay. The gears have been turning ever since. :bananahea

Poulan 25cc update
 

I ran my gas engine again today. The first time since rotating the carb 180°, mounting the engine to my fuselage, and installing the new Seeker II from Polk's Hobbies. Ground based range checks actually improved?!?!? Must be because I was at a different location.

I AM IMPRESSED!!

The RPM readings were better than I expected or even hoped for...

25 cc WeedEater® engine (Poulan),
Master Airscrew 15 X 8 prop (for break-in),
no muffler (not uncomfortably loud, but my muffler isn't done yet),
running slightly rich (4-stroking 80% of the time),
ESSO Synthetic oil mixed 40:1

RMP readings fluctuated at 9640 - 11040 !!!!!! :D :cool: :boxing:

(Before anyone asks, yes, my tach is properly calibrated.)

With that kind of power, what prop do you recommend next?

P.S. More good news - my old starter (standard size sullivan) was able to start it repeatedly with ease.

MORE PROP!!!
 

Nice....
11K is pretty fast for a gasser...
Bump it up to a 16x8....

Look for 7-9K to be your best top rpm....whatever prop gets you in that range.

Are you using standard size PVC for your fuse? I'd Love to see pics on your mounting method.

Great work!

Keep us updated....

CrazyHerb

Poulan with Header/Muffler
 

then maybe your sunlight is out of whack?

seriously, that sounds way too high for an engine that can you start with a standard starter. can you confirm the reading with another tach?
thats much more rpm than a g-23 with same prop so something must be wrong :confused:

dave

Poulan with Header/Muffler
 

Zagnut - I was alone, hence the need for pictures to prove it. I have previously verified this tach is correct by comparing with another tach, and also by aiming it at a light bulb on 60Hz AC power, and get a reading of 3600 (60Hz X 60sec = 3600 "RPM").

CrazyHerb - Using 2" Canadian gutterpipe from Rona/Revy for the fuse. I bought an aluminum strike plate for where you push open a door and cut it into a square. Drilled the holes to match the crankcase of the Poulan and replaced the bolts with slightly longer ones to go through the plate and the plastic crankcase cover. This just barely fits inside the 2" gutterpipe. I then cut out the corners and wrapped the metal around the fuse. I placed plastic doubler inide the fuse al the way around the mount and then placed 6 screws through both. 2 on top, 2 on the bottom, and one each side.

Here's a close-up.

Poulan with Header/Muffler
 

I don't know what to tell you Dave - I guess Sullivan is serious when they label it "HI-TORK". Maybe it's just beginner's luck. Also, it was a freshly charged battery.

Poulan with Header/Muffler
 

strato911, sorry about the late reply. I kinda just forgot about about this thread. I was going to say that your 25cc Poulan should fly your "Blue Heron" just fine. With that much wing and at 10lbs, even a stiff piece of carbboard will lift off. ;)

Not to doubt your RPM numbers, but that is one stout 25cc weedie conversion!!!! My twin-ring G-23 and single-ring 25.4cc Kioritz don't get anywhere near those numbers - and they are both "Pro-grade" weedies. If you can verify that the numbers are correct, I'm buying one tomorrow!! Try a 16x6 or 16x8 APC, and tach it in bright sunlight. I know my cheapo tach gets flaky when the sun starts to fade toward dusk. The fact that it fluctuates 1400rpm kinda makes me wonder.

Also, AFAIK spark ignition gasser 2-stroke engines do not "4stroke" anywhere near as much as glow engines do. That spark plug fires every up stroke regardless, so combustion happens pretty much every time. Now when the mixture is overly rich, it might "misfire" every so often, but I don't think it can "4-troke" 80% of the time. That would mean that the darn thing misfires 40% of the time.

Poulan with Header/Muffler
 

I use the phrase "4-stroking" loosely. You know the sound I'm referring to... when an engine is still running rich, but occasionally gets "on step" to full RPM. Kinda' like:
Bap-bap-bap-bap-bap-brrrrruuuuummmmmmm-bap-bap-bap-bap-bap--brrruuuummmmmm

Almost like a Harley Davidson sound... I assume that was the reason for the fluctuating readings.The RPM's weren't changing wildly. For 20-35 seconds it would be 9600-9700 (sounding rich), then for 10-15 seconds it would be 10200-11000 (with a proper lean sound), then back to the rich sound.

The LHS is closed Mondays, so I can't get a new prop till Tuesday. I'll tach it again then, and hopefully I can get another person with a tach to confirm things.

If I knew I could consistantly convert these with those numbers, I would buy out the surplus center's stock and make my living doing conversions... This may just be beginner's luck, but I'm wearing an ear-to-ear grin. :D

Poulan with Header/Muffler
 

Well, the ear-to-ear grin is gone. I have good news and I have bad news:

Good news: It flew! Tons of reserve power. Almost hung on the prop with an APC 16X8. Seeker receiver experienced absolutely no interference from the magneto ignition.

Bad news: I "Dorked" the plane on the maiden flight, and have no video to post. Not enough control surface on the elevator to pull out, plouged in at full throttle before I could cut it. The coil mount broke off, and the front 16" of the fuse is scattered around the crash site. Everything else is salvagable.

What have I learned? The fuselage should be 6" - 10" longer, and it needs a bigger elevator.

I'll post more details (and pics) in the Crash forum in the next couple days.

Poulan with Header/Muffler
 

wow, yer on the right track but id poke around the giant spad site to see if you can learn from others before your next version.

http://spads.mattclement.com