Fokker Triplane build

[Dogtail2]

Internally varnishing the spar halves before final 1.5mm ply skinning.

 

[Dogtail2]

One of 6 completed spar halves, ready for drilling to take metalwork, i.e. strut & spar mounting brackets.

 

[Bozothenutter]

I see the plans are still available, how much are they? (Not going to build one, just interested)

[Dogtail2]

3 hours ago, Bozothenutter said:

I see the plans are still available, how much are they? (Not going to build one, just interested)

 

From memory the drawings (32 sheets) were about $ 200, but that was a while ago.

[Dogtail2]

Making parts for the aileron cable pulley brackets

 

 

 

[Dogtail2]

Forming 4130N steel for the interplane strut brackets.

 

 

Ready for welding.

 

[Dogtail2]

Acquired some pyramid pattern aluminium sheet for the floorboard scuff plates, Same pattern used on the originals.

 

[Dogtail2]

One of 12 spar mounting brackets, welded up & ready to be drilled for bolts.

 

[Bozothenutter]

Been reading up on these.

Read that after the war it was discovered that the upper wing provided too much lift compared the the others, will that be corrected? (If true...)

[Twobad]

40 minutes ago, Dogtail2 said:

One of 12 spar mounting brackets, welded up & ready to be drilled for bolts.

 

What are the requirements for checking the integrity of the welds?

 

I ask because I was involved in the manufacture of in-flight refuelling probes at one stage, and the checks were pretty onerous.

[Dogtail2]

7 hours ago, Bozothenutter said:

Been reading up on these.

Read that after the war it was discovered that the upper wing provided too much lift compared the the others, will that be corrected? (If true...)

 

I'm not sure about the lift problem you mention, I have not heard of that.  There were some upper wing failures early in the aircraft's operational career, which were found to be caused mainly by shoddy workmanship and poor weatherproofing. The German authorities at the time laid out requirements for improved workimanship etc. They also beefed up the wing structure related to the aileron attachment, this being incorporated in the drawings I'm working from I'm pleased to say.

 

7 hours ago, Twobad said:

What are the requirements for checking the integrity of the welds?

 

I ask because I was involved in the manufacture of in-flight refuelling probes at one stage, and the checks were pretty onerous.

 

The checks on the welds are probably a lot less onerous than with a production military aircraft.  They just need to be inspected by a suitably qualified LAA inspector.    

[Twobad]

1 hour ago, Dogtail2 said:

 

I'm not sure about the lift problem you mention, I have not heard of that.

 

As I recall, the top wing of the DR.1 (and Sopwith) generated over half of the total lift. I don't quote me here though, I'm recalling this from a while ago.  The middle wing is stymied by compression from the wing above and rearifaction from the wing below, so its contribution is reduced. The lower wing is smaller anyway so it's contribution is less.

 

The big problem with with the original DR.1(which I'm sure you are aware of) is that the top wing wasn't strong enough to handle the torsional loads of the ailerons which lead to failures of the early aircraft. 

[Dogtail2]

The jig for forming the interplane strut ends.

 

[Dogtail2]

Making the steel interplane strut ends, formed around the above jig.

 

 

[Dogtail2]

Joining two wing spar halves with ply spacers.

 

 

[Bozothenutter]

Would care to expand a bit on the 'legal' implications of building your own?

I read some about the welding, how about the other stuff?

Seems you have to do some rather extensive bookkeeping regarding certification. 

Is it like : certified parts assemble into a certified sub- assembly,  assembles into a certified aircraft?

[Dogtail2]

 

22 hours ago, Bozothenutter said:

Seems you have to do some rather extensive bookkeeping regarding certification. 

Is it like : certified parts assemble into a certified sub- assembly,  assembles into a certified aircraft?

The book keeping is very simple. 

When the project is registered with the Light Aircraft Association, a 'build book' is issued which among other things contains an inspection schedule which is signed at each inspection by an LAA inspector.

For this aircraft type there are 23 inspection entries to be signed.

 

Here's a quote from one of the LAA technical leaflets:-

 

"7. Frequency of Inspections
The build inspection schedule specifies each of the main inspection stages required for the
project. There may be anything from, say, ten to thirty stages depending on the complexity of
the aircraft type concerned but this does not mean that ten stages means ten visits from your
inspector. Your inspector may feel the need to visit several times in order to satisfy one
inspection stage, especially in the early part of the project as you are learning the construction techniques involved and he is trying to develop confidence and trust in your ability.
Alternatively, he may be able to accomplish more than one stage in one visit, depending on your
rate of progress and ‘organisational skills’.
The inspector should be invited to look at any structure or system just before it is ‘closed off’, for
example in the case of a wooden box spar he will want to see the job fully prepared (including
the internal varnishing and preparation of the closing web) before the closing web is glued in
place, rendering the internals invisible from then on."

[Dogtail2]

Adding triangular section (corner blocking) reinforcements to spar spacers.

 

[Dogtail2]

One closed up and completed wing spar.

 

[Dogtail2]

Three wing spars completed.

 

[Dogtail2]

Turned the spar building table into a shelf to store the spars and get them out of the way, and built a new table for building the fuselage.

 

 

[Dogtail2]

Wing spar and other hardware primed and painted.

[Bozothenutter]

Dare I ask you for the angles of the front half of the frame?

I'm looking for the vertical side tubes, as I'm trying to solder a frame in 1/32.

I have a drawing from a book, that gives diameters and lengths, but it's omitted the angles and I've no proper way of measuring. 

[Dogtail2]

3 hours ago, Bozothenutter said:

Dare I ask you for the angles of the front half of the frame?

I'm looking for the vertical side tubes, as I'm trying to solder a frame in 1/32.

I have a drawing from a book, that gives diameters and lengths, but it's omitted the angles and I've no proper way of measuring. 

 

It's easier and more accurate to measure tube intersection points as lengths along the longerons, rather than try to measure the angles. This drawing should help.

 

[Bozothenutter]

17 hours ago, Dogtail2 said:

 

It's easier and more accurate to measure tube intersection points as lengths along the longerons, rather than try to measure the angles. This drawing should help.

 

Thanks for that!

Good res too!

Will have to fudge the actual dimensions, as it's going into a thin skin Meng...😉

Hence the request for angles.