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Post  dirk gently Mon Jan 28, 2013 1:45 pm

CL planes, CL planes everywhere!
So this time I decided to go against the flow (I'm not sure if that's a saying in English) and show a build thread of an RC airplane.
My PZL 62 is mostly finished, but the weather is to lousy to try and fly it, so I decided to go for another unbuilt Polish pre-war design, the PZL 56 (for some reason, I seem to like these more than airplanes that actually managed to be completed before the war started).
The model is loosely based on this drawing I found online:
Sheet Balsa Fighter P56B_02b

Some technical data:
Wingspan: 55cm
Powerplant: Cox Pee Wee
2ch RC (ailerons and elevator)
weight: so far 130g, but I still have to fuel proof it.

The build pictures:
Sheet Balsa Fighter Dscf2343c
Sheet Balsa Fighter Dscf2342p

I wanted to paint it in white and blue, like the Ł2, an early 1930s reconessaince airplane:
Sheet Balsa Fighter Pzl_l_2_1

but I totally screwed up the swoosh on the fuselage, so I had to improvise a bit:
Sheet Balsa Fighter Dscf2368g

Now I'm waiting for the tank gasket for my engine to arrive, as it seems to be missing it.


Last edited by dirk gently on Tue Feb 19, 2013 1:08 pm; edited 2 times in total
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Post  RknRusty Mon Jan 28, 2013 6:20 pm

Sure, DG, going against, or with the flow... or grain is a common (American)English expression.
Nice little plane you've got there. What engine do you have? The extruded crankcase with a black flange style reed retainer does not necessirally have to use a gasket. The black plastic reed retainer seals between the tank or backplate and crankcase. People do use gaskets, but Cox sold them without one installed on the engines I bought new.

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Post  dirk gently Tue Jan 29, 2013 12:51 am

I have a metal tank Pee Wee (not sure if there are any plastic tank Pee Wees). It's firing up every time and making a short burst on prime, but not taking any fuel from the tank.
I thought the reed valve might have gotten stuck, so I disassembled it, and found that the tank is empty, even though I just filled it up. I noticed there is no gasket, so I assumed the fuel leaked out, and the engine doesn't have any compression in the crankcase.
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Post  pkrankow Tue Jan 29, 2013 9:43 am

Pressure test the tank with a little fuel in it and see where it leaks, use your fuel ball or syringe and partly fill the tank, then cover the vents with your fingers and try to put more fuel or air in. Fuel should spray out of any leaks.

If it is anything like an 049 then the rim of the tank, and the venturi to back plate are suspect. The venturi has a o-ring type gasket, but the rim does not. Some aluminum safe sealant can be used on the rim, doesn't take much. I fill the groove on the tank, clean the excess and inside of the tank, then assemble and clean the outside.

There should be a paper gasket between the crankcase and tank. You can cut one out of a piece of card stock like a folder or playing card, or order one.

Phil
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Post  dirk gently Tue Jan 29, 2013 9:56 am

Thanks a lot.
I actually already ordered one, and before doing any more tests, I will just wait for it to arrive. I really hope the engine will run with the gasket, as otherwise it seems to be in perfect condition. It bursts literally every time I flip it, which is hardly the case with the three other engines I own.
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Post  dirk gently Wed Jan 30, 2013 3:01 am

I weighed the model today, and I'm at 138g (I still need to fuel proof it, so there will be a couple of grams more).
I am however using a quite heavy, 380mAh battery, where a battery of about 150mAh would probably be more suitable. That would save me some 15g.

The problem is that 2 cell LiPos of 150mAh are not readily available for me, I would have to buy two individual cells and make a battery of them myself.
Do you think saving 15g (which is more than 10% of the AUW) is worth the hassle?
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Post  John Goddard Wed Jan 30, 2013 3:24 am

10 percent? Definately Dirk.
If you have trouble getting batts I bought
A few 120 mah nimh's from the Model Engineering
Exhibition. PM me your address I'll send
You one. They're 4 cell and They weigh 12 grams.
Very Happy
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Post  dirk gently Wed Jan 30, 2013 5:39 am

I appreciate the offer, but I don't really have a problem with the batteries, it will just require some work (also, I don't have a NiMH charger).

BTW, how many flights do you get on the Bacaruda before you have to recharge the batteries?
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Post  John Goddard Wed Jan 30, 2013 5:47 am

I've got a 220mah in it at the Mo Dirk 5 flights and it uses about half.

I flew 3 flights with the 120 but don't remember how much it took to top up.

The real interesting one will be when the Full Fathom 5 and it's five (4 digital) servos
flys come the good weather Dizzyman says we'll get arrives, to see what kinda
drain they have.
Very Happy
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Post  Dizzyman2011 Wed Jan 30, 2013 6:05 am

Roll on those 3 days of summer woop woop it's gonna be 72 hrs non stop flying gonna take out shares in red bull !!!
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Post  dirk gently Thu Jan 31, 2013 3:44 am

The engine, happily sitting on the nose of the plane:
Sheet Balsa Fighter Dscf2371
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Post  Dizzyman2011 Thu Jan 31, 2013 3:55 am

Dirk
That's looking good what size tank ate u using homemade brassy or shop
Bought ?
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Post  Dizzyman2011 Thu Jan 31, 2013 3:56 am

Sorry really should study photos I now see the integral tank !!!!
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Post  dirk gently Thu Jan 31, 2013 7:47 am

yep, that's a regular PeeWee with an integrated tank:
Sheet Balsa Fighter Dscf2370x
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Post  Dizzyman2011 Thu Jan 31, 2013 7:57 am

Being the nice bloke that I am my wife loves baking so thought I would treat her to a new set of scales ... The old one don't worry my dear I'll get rid of it for you ....

" alt="" />

Clearly great minds think alike nice digi scales to weigh models !!!
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Post  John Goddard Sat Feb 02, 2013 2:12 pm

Yo Dirk, the Full Fathom 5 (five servos) flew twice today for about 6 mins total.
Bear in mind 4 servos are digital and it was VERY windy so the poor little blighters were under
a lot of strain so drawing a fair bit of current.
I just charged 80mah back into my 220mah to top it back up again.
Very Happy
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Post  dirk gently Tue Feb 05, 2013 12:36 pm

After installing the tank gasket (and the venturi gasket, which was also missing), the engine works Beer Cheers
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Post  RknRusty Tue Feb 05, 2013 8:51 pm

dirk gently wrote:After installing the tank gasket (and the venturi gasket, which was also missing), the engine works Beer Cheers
Bravo! Time to fly.

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Post  dirk gently Wed Feb 06, 2013 4:31 am

Actually, this motor does start easily, but plays "chase the needle setting" and quits before the tank is empty. I may need some more time to figure it out. The Pee Wee is actually so small that I usually flood it during priming and have to start it with the needle valve almost closed, and make it richer once it starts, kinda the opposite of the usual procedure.
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Post  dirk gently Tue Feb 19, 2013 1:10 pm

I measured the RPM, and the engine is doing 17500. This is not as good as John's 20k, but it still gives 5.6oz of thrust.
This should be more than enough for a plane that is below 5oz.

And here's a photo:
Sheet Balsa Fighter Dscf2384v
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Post  shell shock Tue Feb 19, 2013 1:30 pm

That looks real sharp man. was the plane built freehand or did you use plans?

-Shell
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Post  dirk gently Wed Feb 20, 2013 1:34 am

I used drawings of the airplane that I found online. I also made some cardboard templates to help me cut out parts from sheet balsa.
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Post  dirk gently Sat Apr 20, 2013 3:28 am

I took this plane to the airfield today. This time (for a change) I had no problems with starting the engine. The problem was making it run in the right direction Smile. I finally succeeded after 10 tries or so.

I gave it a toss, and it turned out there's waaaay too much throw on the ailerons. I hit the ground and broke off the propeller. Times like these, I wish my radio had expo. Sure enough, I forgot to take a spare prop.

Anyway, I tried some test glides to see if it's stable in the air and to find the correct trim. After a few ticks of the trimmer, it glided nicely and controlably, with no tendency to spin. The GC seems correct. The glide is quite slow, despite the sheet construction, this plane is fairly light. Perhaps I'm overoptimistic, but I think it will be a good flier once I reduce the throws.
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Post  anm2 Sat Apr 20, 2013 5:56 am

That's a nice looking plane you made. Is the wing pure sheet balsa, or did you use ribs? It looks like you have a fairly significant airfoil. Andy
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Post  dirk gently Sat Apr 20, 2013 10:48 am

It's 2mm medium sheet balsa, bent over just two ribs near the center of the wing.
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