Q2/200 fuselage foam ?

[Justin]

Hi Folks,

Can anyone tell me what foam was used in Q2/200 kits for the fuselage ?  Which thermoplastic, and what density ?

I have figured out a way for the homebuilder to make new fuselage cores. I guess the original cores are no longer available.

 

[Marc Zeitlin]

7 hours ago, Justin said:

Can anyone tell me what foam was used in Q2/200 kits for the fuselage ?  Which thermoplastic, and what density ?

It's been a damn long time, but given the molded shape and configuration of the Q2/200, I'd bet a lot of $$$ that it was 3/8" Divinycell H45, 3 lb/ft^3. That's a fairly standard foam for Rutan derivative canard fuselages.

[Eugen]

For sure it was min. Divinycerll H35 or larger.

 

https://aerobase.weebly.com/q1-bill-of-material---source--spec.html

[Justin]

Thanks Guys,

From the plans I reckon it looks like 0.5" thick, but H35 or H45 sounds about right for the material.

Eugen, I have followed your super Q1 project, and your materials link is superb. Thanks !

I will post my fuselage core idea at some time. It is basically a foam plank system, as I have used in many boats. I see no reason for the horizontal split in the forward fuselage part.... only in the tailcone part. I will figure out the tooling for this.

I have no idea if I will build a Q2/200, but I am fascinated by the really logical design, that I used to think was just freaky. Well, it isn't. It has really short load paths all concentrated in a very compact design. It is utterly brilliant.

Cheers,

Justin

[Justin]

Hi Folks...

Well, here is the new Quickie Q2 helicopter !

It is really the bare bones of a fuselage foam core jig concept. This will get another 9 formers in something like 3/8" MDF, arranged on a spine, and braced to the 'helicopter skids'. The entire fuselage would then be planked in H35 Divinycell. I hope this can be found in 1/2" thick sheet, but it is almost impossible to find out if that is available. I would need to 'expand' the complete plank layout. In shibbuilding this is called a 'shell expansion' or 'plank expansion', and in foam it would be nice to avoid planks tapering to zero near the tail. A layout with 'nibbed' ends needs to be devised. I can do this in Rhinoceros.

A suitable adhesive to go between the planks is required. It could be dry micro, but there are adhesive available specifically for foam bonding that are as strong as the foam, and as light, and as easy to sand fair. I don't yet know of a suitable one for H series Divinycell.

The technique would be to start planking round the sides and bottom, and gradually remove the bracings to the 'skids'. The foam core will reach a stage where it maintains the dimensional stability of the whole core on the spine part alone. This spine part might need to be made of steel tube, but the skids could be wood. All the formers must have polyethylene stapled on their edges to prevent foam core adhesion to them. I foresee that the spine part has bearings at both ends, so the fuselage core could be rotated, once it is dimensionally stable. All pins constraining the planks to the formers can be removed once the core planking is complete. Then it can be faired and externally skinned. I think the front-rear fuselage can then be carefully sawn, along with the canopy frame. The rear fuselage/tailcone part can have the waistline split cut. The front fuselage can remain unsplit at the waistline. There is plenty of access to make all the internal fairing, inner skinning and structural additions.

It could be that a further external longitudinal support is required, along the top centreline of the fuselage, but it would be nice if it can be done without it.

There is a long way to go with this concept; especially the tail end of it. All ideas are welcome.

Cheers,

Justin

Fuselage-Jig.zip

Edited March 27, 2023 by Justin
to make changes !