Detailed report: The rebuild of a PIPER 1:3 with 1.417" after crash - RC Groups
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Oct 29, 2012, 12:18 PM
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Detailed report: The rebuild of a PIPER 1:3 with 1.417" after crash

Normally I do start my Piper at full throttle to evitate any kind of problems during the start. That's very safe for the plane but it just doesn't look scale when you start like that. So after years of starts at full throttle I wanted to start her slowly. Not being used to that procedure and facing the end of the runway I pulled the elevator to hard and suddenly had her torquing some feet over ground.

The motor is strong enough to torque and so for some seconds I gave full throttle but didn't manage to stabilize her and so - in a moment when she was only a few feet over ground - I pulled the throttle back totally.

My PIPER "landed" on the tip of her left wing and then she harshly touched ground with the tail wheel and then forwards on her propeller. So the left wing, the tail wheel and the propeller were the parts that were damaged.

Rebuilding the left wing

The first we did was to remove the plastic sheet. The first diagnose then was that the damages looked much worse than what it would actually take to repare them and so we optimistically scheduled an afternoon's work to fix it.

First we repaired the fins that were broken without any material lacking. We pulled them back into their original position and joined them with superglue. For that we used a hollow needle with the superglue bottle; that way we can allocate the superglue very precisely and we can inject superglue into the woods as well. Inner healing . . .

Then we looked after the wing ear which had suffered most through the crash.

From ply wood (2mm) we made a reinforcement . . .

. . . adjusted . . .

. . . and then glued it.

Then the badly injured binding piece (holm) got an additional reinforcement.

This building lot was then injected with superglue.

So now the wing was fully repaired and just lacked the plastic sheets from ORACOVER to be ironed on.
That's the advantage of wood structures - even seemingly big damages can be repaired quite easily.

Here's a close look on the repaired wing:

As soon as I find the time I'll post the pictures of the next steps we took . . .

Happy landings - Peter
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Oct 31, 2012, 12:10 PM
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The ironing of the plastic sheets . . .

So now the ironing starts; first we covered a section on the downside of the
wing, where the original plastic sheet had a long cut.

The strictly rectangular shape of the wing made it very easy to cut and iron the
plastic ORACOVER sheet . . .

So far the ironing has just taken half an hour. The plastic sheet was just
attached on the borders of the wing with the electric iron, the big surface in the
middle was shrunken with a heat gun. That was fun and veeeery quick. So now
there's only the wing ear left . . .

The lower plastic sheet has been put on, but no yet shrunked in order not to
bend the wing ear just from one side. First we ironed the upper plastic sheet on
and then shrunked both sides by turns.

So five hours after tearing off the original plastic sheets to judge the damages
the wing was o.k. again.

I now prefer the looks of the left wing over the right one. The ORACOVER sheet
is better quality than what the chinese used as original sheet . . .

So now we continue with the rebuild of the tail and the tail wheel.

Happy landings - Peter
Nov 04, 2012, 07:27 AM
Registered User
Hi there,

so here we go on with the . . .

Rebuild of Tail & Tail wheel

The damages the tail suffered were only partly due to my pilot error. Pulling off the plastic sheets we
discovered, that the tail of this PIPER had not been built well in China. So we decided not just to
repair the damage but to reinforce the wooden structures according to our standards.

On the picture below you can see that the holm is not glued to the tranversal end because it is some
millimeters short and if that were'nt enough . . .

. . . the upper two holms (see red circles on picture below) do en in the middle of nowhere. They
weren't broken through the crash, the really do end in the nirvana. The structure of the tail was held
together only through the part that carried the tail wheel. How that withstood so many landings is a
real miracle.

So now we teared away the plastic sheets to evaluate well the damages to the structure.

With a special knife we then straightened the balsa edges to make it easier to produce and glue
the parts to rebuild that part of the structure.

Rattling the struts we realized that there were yet more hidden damages under the cover. So we
detached the servo . . .

. . . and teared more plastic sheet away.

As much as possible we fixed the existing structure and handled the plastic sheets with care in
order to able to iron them on again after gluing the damaged parts together.

While the glue was drying we ironed the original foil on again.

Where we detected fissures we injected superglue with the hollow needle into the wood structure.
That's a very fast way to repair and it is amazingly robust afterwards.

Here another balsa edge is straightened . . .

So now the original structure is repaired wherever it was possible and all damaged parts that had
no remedy are removed. The next step will be the production of the missing parts and then the rebuilding.

To be continued . . .

Happy landings - Peter
Nov 07, 2012, 10:15 PM
I see a lot of Piper Cubs with ground handling problems and the main reason is that the undercarriage is too far forwards.
If it was closer to the balance point it would be a lot easier to steer.
Ok it would nose over more but which is worse?
Nov 08, 2012, 02:44 AM
Registered User
Hi Jim,

you may be right there. But there is yet another point about the undercarriage
and that is that it's attachement to the fuselage would not support a harsh
landing. And because the wheels have no negative camber the Piper tends to
break out even more. That is with the "World Models" Piper - I don't know about
the Pipers of other manufacturers.

So good bye scale starts and hello starts at full throttle. But that's it with the bad
news. She flies heavenly and the landings are so easy that you don't push the
undercarriage to its limits. And even at higher prices I haven't seen an ARF kit
that easy to finish.

Does somebody here know a kit of a plane that size and that easy to build - even
at a higher price? I'd be interested . . .

Happy landings - Peter
Nov 08, 2012, 10:57 AM
Registered User

And on we go . . .

Hi there,

so now it was time to rebuild the wooden structures :

On the following picture one can see the little board that held together the structure of the tail and the tail wheel (see
red frame). This little board was even weakened by a recess path for a metal strip (see some pictures farther down).

So in order to avoid the weakening of the replacement board we rasped down a path for that metal strip in the
plastic of the tail wheel suspension structure. This plastic piece doesn't suffer any by this while the wood structure
would be severely weakened by doing it there.

Then we took the measures of the fuselage . . .

. . . made notes . . .

. . . and introduced those measures into our turbo CAD software.

That was then cut out by our cnc-mill:

Here are the finished parts . . .

. . . loosely put together to test the adaptions.

But not every part fitted just like that and so we reworked the parts a bit.

We made this frame to reinforce the wooden structure in this part of the tail. The original structure didn't have such a frame.

We made yet another frame to reinforce the end of the fuselage. Additionally we extended the two holms that end in
the middle of this picture, shortly behind our first new frame.

In the end we relocated the frame on top, that carries the tail wheel.

That marked the end of the repairs on the wooden structure.

I'll be back with the pictures of the ironing of the plastic sheets and the finishing.

Happy landings - Peter
Nov 12, 2012, 02:46 AM
Registered User
Hi there,

here is how the job was finished:

The next day the glue had dried off and that's how it looked:

Then we tested where to locate the tail wheel:

Then we sanded the wood structure . . .

. . . and started to iron on the plastic sheets - red on the bottom and white on the sides, just like it was before.

Then we marked the three holes for the screws of the tail wheel suspension.

Then we injected superglue into those holes in order to make them more stable so that they'll really hold those screws.

Then we covered both sides whith white ORACOVER foil.

Then the tail wheel was mounted:

The carbon trifoil airscrew had also been damaged:

Here she is with the new one:

So there she is again - ready to fly. The repair was worth the while and I'm happy to have my PIPER back again.

Crash ???? What crash????

So now she's back on her winter storage place under the roof - very scale . . .

Happy End !

I'll try not to return with a thread in this crash and rebuild section, but I do hope to see you all in
another thread elsewhere.

Happy landings - Peter
Nov 12, 2012, 11:20 PM
Registered User
RCSwitz18's Avatar
Next build log???
That bipe!
Nov 13, 2012, 02:44 AM
Registered User



but being a german I didn't get the message - what does "That bipe" mean?

Nov 14, 2012, 12:15 AM
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RCSwitz18's Avatar
"Bipe" is just short for BiPlane
Nov 14, 2012, 03:09 AM
Registered User

The bipe is a WACO YMF-5

Hi RCswitz18,

got it, thank you.

Well, this was my first thread here on RC-Groups and the truth is that the frequency with which this thread was visited, is very, very low. Used to thousends of clicks in my german forum here I only got 260 during the whole period of posting the thread. That means that some 30 - 40 people may have watched it and for that frequency I'd rather do something else.

The build log of the WACO is on my website but it's in german; of course the pictures do tell a story too, so here are are the links to my bipes, the WACO YMF-5 from FMBB . . .

. . . and the ULTIMATE from Lembeck.

The WILGA thread is interesting too . . .

I intended to translate those and post them but it just doesn't seem worth the while. If the "switz" in your logname does mean you're swiss, then you might be able to read the german pages . . .

Happy landings - Peter
Nov 14, 2012, 10:31 PM
Registered User
RCSwitz18's Avatar
My last name is Switzer, but pronounced differently than the Swiss pronounce it.
My buddy I work for (great friend as well) speaks German and thought my last name was
Schweitzer, but its pronounced Switzer. "I" as in Ice cream.

I cant read German either. I wish!
Nov 14, 2012, 10:34 PM
Registered User
RCSwitz18's Avatar
Also, Google Chrome (my search engine) translated your build into English!

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