pc55bomber

Hi Guys
Take a look at the lastest addition to my fleet, a 97" Piper Pawnee PA25.
http://www.austars-model.com
I am slowly replacing my smaller models with bigger ones, easy to see as I get older.

This is one awesome ARF and is excellent quality throughout, I was always impressed with my H9 40 size Pawnee and this is every bit as good if not better and even looks the same, althought there are some differences.

I like my Ag planes this makes a total of 4 in the hanger, 110"Ag Husky, 70" Kyosho Agwagon, 40 size H9Pawnee and now this Pawnee.

Heres a pic for you.

Cheers
Paul

Bill Diedrich

Removed at the request of PC55Bomber

pc55bomber

Hi Guys
Seeing that I got the very first model that arrived the pics you see on the Austars web page are mine.
Have already done a lot of work on the Pawnee and the more I see the more I like this model.

1. Started with the Canopy, its all precut to size and fits like a glove, I crewed it on in my usual way using socket head button screws making sure to have the hole in the canopy slighty bigger than the screw to allow the canopy to lay flat against the fus.
2. a few shots of the internal structure and the unusual wing joiner made from ply and fibreglass sheet, very strong.

pc55bomber

Continuing on:
1. Installed the engine next which was pretty straight forward other than making a small mod for the Pitts muffler I decide to use
had to cut a small amount away from the bottom of the engine box to allow room to fit.
Trimmed the ply down remaking the keyed interlocking pieces to help with strength and made a ply insert that simply slides in and goes directly on top of the existing floor of the engine box, lightened it up by drilling some holes in it and epoxied into place.
2. Fitted the MLD 28cc engine using the included template which makes things very easy, using the included standoffs which gives you about a 5mm gap between the spinner backplate and the cowl, probably a little more than I would like but it looks fine. Used big washers both inside and outside of the firewall to spread the load forces on the ply.
3. The hole in the lower part of F1 was completely sealed off using some 1/16" balsa to keep the fus clean on the inside.
4.The throttle servo was next and I placed this on the outside of the engine box inverted using some ply and maple mounts. Made a plastic servo horn to fit the walbro carby and used a 2/56 pushrod.
4. The entire front of the plane was then sealed using a commercial based epoxy that I use on all my planes, great stuff nothing touches it once set.
More Later
Cheers Paul

pc55bomber

Thanks Bill.

pc55bomber

Heres some shots of the final engine installation.

The ignition box is inside the engine box directly behind the firewall.
Heres a shot of the hatch assembly showing the quality of the balsa and hardwood plus the fit, very nice.

Cheers
Paul

Lotsofcrashes

That engine install is real nice Paul, a tidy and practical use of all that room. No wonder you like the bigger planes. I wish I could do that with my current build.

Lotsofcrashes

Hey Paul, heres what i though when I looked the plane over from your pics.

pc55bomber

Hi Lotsof crashes

The fus is made of ply and as such is quite strong, I have not had any issues with similiar built airframes.
Not saying they wont break though, everything has is limit.[X(]

Its an easy mod to add some 3/16 square or bigger hard balsa diagonal bracing (warren Girder bracing see pic) to the sides of the fus, this will add heaps of strength.

Its a good idea with all ARF's to go over every joint with some thin or medium CA to catch the areas where the factory glue has missed or misaligned parts.
I must say that this Pawnee airframe is very well put together with no gaps that I can see, very impressed.

Another weak point in all ARF's is the undercarriage area, if you can get to it beef it up or when the inevitable happens fix it properly.
This Pawnee is no different so it may pay to beef the area up although I will wait and do it later.
All gassers shake rattle and roll at idle, remember to balance your props and spinners , this is a must.
Cheers Paul

pc55bomber

Hi Guys
Control surfaces.
All the hard tedious work is done for you here, surfaces are already prehinged and only need gluing in place. I used 15 minute epoxy on all hinges and the entire job did not take long at all.
I used vaseline on the hinge joint to keep the epoxy out,wipe off the excess when finished.

The rudder and elevators are built up and shaped not just a flat plank style which the stab and fin are, this gives a nice overall and practical finish.

Servo installation was next for the wing. Again all the work has been done , all you have to do is trim the covering, drill the holes to suit your servo and screw them in, easy.
Fit the servo's with a small gap underneath them, use a piece of cardboard, works nicely to prevent vibration destroying your servo.
Drill 4 holes in the servo hatch and screw it on.

Next task was to fit the control horns, all of the supplied ones were used and they are more than sufficient for the job. The nylon clevis is a tight fit on the pushrod and the pull pull rods secured to the control horn with a small scew, very nice fit.
The horns are the typical 3 screw triangle ones that has a nylon screw on piece to attach the clevis. I always put a nut each side of this part to make sure it does not move.
The pull pull cables were attached using crimps, with heatshrink over the lot. The servo end of the cables is fitted directly to the servo horn and has no adjustment.

Cheers Paul

pc55bomber

Next task was to attach the wing struts. I decided to set up the wings under load to remove any movement when assembled as there is a bit of vertical movement when the wings are on without the struts, this all comes from the wing joiner.
I chocked the fus off the ground and set up some paint containers under each wing so there was no more upward movement and each wing was the same distance from the ground. This took some fiddling.
Attached the struts to the wing, drilled the holes thru the strut on the fus end and used the supplied blind nuts and bolts to secure.
It all worked out well, so then I attached the fin and stab.

First removing the covering from both so the glue would have contact with the balsa, both were a very good fit in the fus.
Used 15 minute epoxy again which gave me time to get it all squared up with the wing, I had to use a small weight on one side to level the stab with the wing.

Next item was to glue the elevators and rudder in place again using 15min epoxy easy task as all the hinge work is done for you.
The moded tailwheel was also fitted at this point which attached to the rudder by a plastic arm that was bolted thru the rudder, first time I have seen this type of rig. I usually mod all tailwheels so they actually give you some suspension as the kit ones are simply far to hard. Used a piece of KS music wire with a dubro tailwheel, which I have since replaced with a larger wheel as it looked too small.

Also a picture of the throttle pushrod setup and my special choke lever that is accessible thru the front intake hole in the cowl.

Cheers
Paul

pc55bomber

Finished fitting the electronics.
All the servo extentions have been secured with some heat shrink for safety.
Usually use the multiplex 6pin plug for connecting the wing wires to the fus, 1 plug does all and is easy and practical to use, each plug has 1 aileron and flap servo.
Then made up a harness to go from the RX to the wing plug, ensure you have the polarity and signal wires correct using a mulitmeter before plugging it in to the wing. Each harness drives 1 aileron and 1 flap.

The switches are a snack to fit as all the holes are precut for you, a normal small switch and 2 larger EMS type switches on both sides of the fus, just cut the covering leaving about 3/16 of overlap and insert the switch, nothing could be easier.
Used ESM type switches for RX and 1 for the ignition circuit. The batteries are cable tied to the wing joiner box, giving the correct CG with no added lead.

Setup the igniton circuit using a 5cell NimH pack running to the switch, then to a hextronic voltage regulator set to 5volts, to an RCxel opto cutout switch to ignition.
The switch enables the whole system to be shut off and the cutout switch lets you kill the ignition from your radio.

Checked that everything works and then cable tie and tidy up the wiring using some spaghetti wrap.

The fuel tank hangs from its own tray over the CG and I like to use the Dubro Kwik fill valves giving easy no fuss fueling. The tank is wrapped in non slip material and velcroed to the tray.
Cheers Paul

pc55bomber

The cowl is nicely made and has holes that could be used for landing lights if you wanted.
Fitting the cowl was pretty straight forward with not much having to be cutout.
Lining up the cowl screw holes is a pain but all turned out fine.
Just a small a teardrop shaped hole for the plug and 2 small cuts for the pitts muffler.
Used 3mm nylon bolts to secure the cowl as metal ones usually loosen.

Cheers
Paul

pc55bomber

Hi Guys
All thats left is to balance it.
I have devised a way to balance big planes easily and on your own, using strong twine and a piece of ply, this depends on how many wing joiners there are.
Won't work for everything but works well with these types of setups.

Hard to explain, see pics.
1. One wing joiner if the CG is on the joiner.... Have the plane setup on the ground with a gap between the wing and the fus, loop the twine around the joiner both sides , stand over the plane, take up the slack and lift, see how it lays and make your adjustments to get the CG correct by adding lead or moving stuff around.

2. Two joiners or 1 joiner and incidence pin, CG not on the joiner...Have a ply plate about 1" wide long enough to go under each joiner/s/incidence pin, tie the twine to the ply and put the ply plate (on its edge) under each joiner/s/incidence pin and as above take up the slack and lift, your lifting the plane with the ply plate under the joiner/s/incidence pin, you may have to move the twine/ply plate to get the twine on the CG as this is the pivot point.(the correct CG location) Adjust as necessary to get the CG correct.

3. If the plane is too heavy, and it will be after you do this a few times, put it on a table, or leave it on the ground just use longer twine, and tie it to the roof, using the twine /ply method above, so its just off the table/ground, it will seesaw until you make your adjustments to get it spot on. As you only need it about 2/3 inches in the air, it can't fall and break and you only have to lift it once so you can take your time doing it right.

Cheers Paul

optech

My Feedback: (9)

I wonder if this Pawnee is the same one offered by Texas R/C here in the US. http://www.texasrcplanes.com/26pipaonor.html

Mike

pc55bomber

Hi Mike
I'am pretty sure it is the same one, although its much cheaper for you guys.
Cheers Paul

pc55bomber

Hi Guys

Well she’s all finished and maidened.

The control throws in the instructions are way out, (like 45Deg) I don’t think so, so I set up what I thought would be a good start for the airframe, worked out fine for me, I can measure these if anyone wants the info.
CG was set as per the book, on the wing joiner box.

The engine had not been run so I left the cowl off for the initial startup, it took a fair amount of priming and some fuel squirted directly into the carby to get it to fire.
I then used my nitro starter to fire it up which took a few turns before the dry carby was up to its task.
It idled pretty sweet right away so let it run for about 5 mins with varying throttle settings, tweaked the High needle a little to get a transition and then replaced the cowl.

The day was bleak and windy not the best weather at all for a maiden flight.
Taxied it out, and I have found that my Ag planes all taxi sweet with no tendency to tip forward at all, lined her up and slowly opened the throttle, straight down the strip and she was airborne in about 8 ft due to the wind but no problems she just climbed away nicely.
A small amount of aileron trim was all that was required to get straight & level flight.
Did a few circuits and tested the stall, none to speak off, flies great, very much like my smaller H9 Pawnee.

Had 3 flights with 1 deadstick on approach which was no issue at all.
The engine quit due to sucking air bubbles into the fuel line which I tracked back to the tank. It was shaking too much at low fuel level so some remedial work will be done here; also the tank actually slants forward, not the ideal layout.
So a few tweaks and more engine running is in order.

First impressions are good and this will be a keeper for sure, I will probably sell the smaller one, although reluctantly.

Cheers
Paul

optech

My Feedback: (9)

Sweet..... I gotta say though that the color scheme on yours is much nicer. I'm a little surprised more people have not jumped in and commented on your plane. Looks great in the air. Good job!

Mike

Lotsofcrashes

it does look good in the air, looking forward to the video  !!!

pc55bomber

Hi Mike
Thanks, its a nice plane for sure.
Yeah the other one is a bit drab but add some rego no's etc and it would be a lot better.
Bit miffed as to why the thread is quiet I thought there would be more discussion and interest.

Cheers Paul

pc55bomber

Hi Lotsofcrashes

Thanks mate, planning to have some video in about a week.
Cheers Paul

witooa

Hi Paul, Receaved my 97" Piper Pawee today, Looks well built & the finish is A1. I am gowing to try to fit a ASP 160 twin tight fit if not i will fit a 26cc gas, Dont want to butcher the cowl. Would the 160 twin tow say 2m gligers ok? Thanks for your report thet inspired me to get the kit & I like Auatars servies. Cheers witooa.

pc55bomber

Hi Witooa

The 160 will be heaps of power for towing 2 mtr gliders for sure. This is a light weight airframe for its size so you dont need a lot of power. I have since beefed up the landing gear by adding more braces and also some aluminium angle bolted to the side of the fus. Rock solid now.

I have made some changes to tweak a few things , will take some pics later.
Cheers
Paul

witooa

Hi Paul
Yes it is a very light airframe for the size, I guess they cater for electrec these days. I have a 1/4 scale PT-19 Great planes ARF with a 120 Magnum its a lot heavier airframe,they weren't built for electrec them days, Looking forward to the pictures updates I meed good landing gear our field has the odd 1 or 2 rabbit holes to dodge. Have you any idea for a syray system to set it off, say talcom powder or similar ??
Cheers witooa.

SkyPilot101

Paul,the Pawnee is a nich plane, either love em or hate em I hate em but that is just me. The ag in huskey on the other hand is the ****! What kind is it? At 110" it sounds sweet. Keep the rubber side down mate