Frank- trying to make an 80 year-old retired pilot smile- a 50" span Tiger Moth

[Frank v B]

An elderly gentleman walked into John's Hobbies on the Danforth and desperately wanted to build a 50" Tiger Moth biplane from plans.  After many visits he appeared to be stuck.  Roger called me to see if TEMAC could help in any way. 

I picked up the plane today... no plans.  The wings were sheeted with balsa and the top wing was mounted.  The bottom wing was loose.  Nothing ahead of the firewall, no power system.

Objective:  to get the airplane to fly... even just once.

Background:  The gentleman was a TCA (before Air Canada) pilot and flew just about everything.  He was captivated by the Tiger Moth because it first hit the air the year he was born.

Approach:
- make the plane strong enough to fly by going over every glue joint and splicing patches in damaged areas (hanger rash)
- supply and install a power system.  This appears to be a .20 size 1986 design published in the British magazine RCM&E as a free plan.  He has the glass cowl as well.
- supply and install a radio system. TEMAC will donate a 72 meg radio.
- give it back to the owner in stages so he can attempt to cover it.  If it works.... great.  If it is difficult for him, I will cover it.
- fly it at TEMAC with the gentleman standing beside me!

I will post photos of the plane on day 1.  Subsequent photos will show the strengthening, patching, power calculations and all other steps required to make it flyable.

Here is why.  About 5 years ago I was given a finished airplane. Powered it and flew it.  On the 5th flight the wings folded at about 75' altitude at 3/4 throttle.  It turns out the wing dihedral joint was made with balsa.  Not a bit of plywood to be found.  I vowed never again to fly a scratch built airplane that I did not inspect below the covering.

Frank

[davidk]

That's a beauty... and a humbling project.  Nicely done, Frank.

Please keep us posted about maiden day... I'd love to see it in the air.

[Frank v B]

I will keep you posted on the progress and publish the maiden day.

Here are photos of the model.  Quite rough but it will fly.

96- the wings
98- I opened up the bottom skin and confirmed no bracing on the dihedral joint.  Everything was butt glued.  This wing would have broken halfway down the runway on the maiden take-off.
99- wingtip- in rough shape.
05- fuselage
06- top of the fuse.

Frank

[Frank v B]

First decision- open up the bottom of a wing to expose all the glue joints.

Findings on the wings:
- only about 30% of the wing sheeting was attached to ribs.  Applied wood glue at all ribs to make 100% glue contact on the top sheeting.  Done.
- The centre joint was not continuous, not spliced, not reinforced at all.  This joint would have failed immediately.  Will re-do the joint completely.
- The hinge gaps are quite serious and need to be reduced significantly.  I will re-hinge the ailerons.

The centre joint is troubling.  I will re-enforce it as much as possible, re-sheet it and fibreglass it to take the place of a proper centre joint.

Frank

[Frank v B]

The first info about the owner is trickling in.
- he flew for Trans Canada Airways before it became Air Canada in 1965
- he flew everywhere within Canada
- he flew DC-3's, 6's and 8's

Roger will get more details when he returns to the shop.

Frank

[Frank v B]

Wing dihedral joint- ready to glue in place.

problem:
- none of the spars were continuous to the centre joint
- the wing has both dihedral and sweep

I tried a carbon rod but there is not enough glueing area.
Ended up with a piece of 1/2" x1/2" hard balsa because it was easy to shape, then wrapped it in fibreglass cloth to strengthen it after shaping.

photo 08- shows the centre section cleaned out of everything that was not a rib or a spar.
photo 09- shows the fibreglass-wrapped new spar, the slots cut to slide it into, the small piece to slip between the double spars, the two shear webs (tooth picks are poked into them as pointers) to spread the spar load between the existing upper and lower spars.

Note the balsa added to the leading edge between the ribs for the leading edge dowels.  It will be trimmed afterwards.

Ready for gluing.... photo 10...glued!  This photo also shows the yellow wood glue to adhere the wing sheeting to the ribs.

Most of the final strength of the centre joint will come from the fibreglass wrap after the sheeting is finished.

Frank

[Frank v B]

Wings, continued.

Photo 13- Everything glued in place and drying. The piece of balsa with the green pin in it is the back end of the wing dowel brace.  The front end has been installed.

Photo 11- While the bottom wing was drying, I opened up the top wing.  I heard some complaining (cracking) when I stressed the centre joint.  Decided to open it.  OMG!  a spar is pre-broken (knife tip points to it).  All this needs to be braced.  As well, there are no hard points for the wing center hold- down and the inter-plane "N" struts.  Will have to add these.

[Frank v B]

Fuse:
Photo- 14- shows the back of the fuse (turtle deck) with random seams.  Decided to open this.
Photo- 15- shows 3 layers of 1/16 balsa on the turtle deck.  Stripped each layer away.  The photo was taken after the top layer was cut away and shows layers 2 and 3.
Photo- 16- under the 3 layers, the gaps between the formers are filled with 1/4" balsa.

Will have to cut things back further then decide how to tackle this.

Problem: Converting a gas to an electric plane starts off tail heavy.  These extra layers add more tail weight which is a problem.

Will figure it out.

Frank

[piker]

That's a hell of a project, Frank... but a very cool one.  I'm following along.

As you're doing....

Get the structure stable, then with a good sanding and filling, and more sanding, and it'll look good.  It looks reasonably straight... right?

It won't be the lighten build when finished, but I'm sure you'll have it looking good and you'll get that smile that'll make it all worth while.

A quick covering lesson may go a long way to help him achieve good results.

Robert

[Frank v B]

Rob,

Thanks for your support

re:." .. then with a good sanding and filling, and more sanding,...."

This could probably use 50 grit paper (sharp rocks glued onto paper) and an electric belt sander.

Frank

[Frank v B]

Wow!  Tackled the fuselage. 
Removed the entire top and bottom.  Look at the floor on my shop!

Here is why my decision:
- The weight at the tail!  There were 4 layers of turtledeck totalling 3/4" thick.  Faster to build new versus re-build the old.
- the sheet balsa fuselage sides were not attached to all the cross members.  Had to get my hands inside to attach the sheet sides to the structure.
- there was a hidden split in the top longerons just ahead to the fin.  This is right where tail breaks happen on hard landings.  Don't ask how I know this.   Have to brace them.
- a couple of cross braces were loose or not flat with the surface.

Photos:
17- The fuselage carnage on my shop floor
18- the break/joints just ahead of the fin
19- stripped top and bottom of the fuse.

Frank

[msatin]

WOW!
Will you be bringing it to the next meeting?
I'm also curious to hear how you will decide on motor and esc size

[Frank v B]

Mark,

re "Will you be bringing it to the next meeting?"

The pile of wood scraps or the plane?

Will bring the plane so you can prove to yourself why I should be certified as "nuts".  As for the scraps.... garbage day is Wednesday.

Frank

[davidk]

re: As for the scraps.... garbage day is Wednesday.

You're kidding... right?  There's a whole plane in there !!!

[Frank v B]

David,

re: your "There's a whole plane in there !!!"

No, I am not building a 12" span biplane out of the scraps....like your mini Warwing.

Frank