80's all foam FAI combat models

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Flew it on Sunday, winds down to gale force 7 but it had to be done

I knew it was a bit tail heavy so I put some extra weight on the front to level it up. What I forgot was that the bladder compartment is just behind the CG, so when I loaded it up with fuel it pushed the CG back even further. Vairy Hairy, still it amused Sam and Martin no end.

Not to worry, I got it down OK, all it needs are some extra extra long bearers.

Not one of my great successes but all part of the learning process I guess.

The next one will be great
Tim

Platinum member

Speaking of 1980s models - does anyone have any details of the ones Monique Wakkerman was flying in the early 90s? Fairly thick wing, NO spars!

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My first "Foaminator" is now done, ready for Scratchwood. I'd post some pictures but I can't get them small enough with my camera / computer setup.

It is 28" span 10" chord (sound familiar?) with the elevator attached to the wing trailing edge (can you tell what it is yet...?) and with a CS Oliver it weighs a tad over 13 oz. Which is *very* light for a D@min@tor.

It is one piece of white EPS foam cut to a 1 1/2" thick aerofoil (taken from the 'Wot 4' for the RC fans out there...) with no spars at all and covered in ProFilm. The pod is a flat blade inserted into a slot in the LE, the tank is a mustard tin I had lying around. It's short and stumpy and thick and with the film on is nearly as stiff as a balsa Warlord.

Being light it is nose heavy so should be well stable, but we'll see.

If it goes well I'll be doing them as kits and RTF. You have been warned...

Simon.

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I think I remember a model by Vernon Hunt from around this time, which had a similar shape wing to the Boomerang but was balsa with a foam L.E. and so avoided ferocious' criticism ie

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I was flying combat during this era, these models
won't take a fraction of the punishment that a modern
combat model will.

It seems almost impossible that an F2D model can smack
into the ground and be flyable with a prop change but it
happens time after time, it almost never happened for me
in the Boomerang era when we were running Conquests,
Rossi's and Nelsons.

I'd be building modern.

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I have to agree with Steve. His Boomerangs were better than the Zinger, as published in Aeromodeller. I went on to develop larger Zinger-style models with more area, longer tail moment & lighter everywhere behind the spar, to allow an engine position way back. Fabulous flyers, but way too fragile. My conclusion was that all foam models end up too heavy in F2D. The Russians really got it right when they went for a strong D-box leadign edge & open frame at the rear.

If you're after crash-proof combat models for training, the smaller stuff has it on a plate. Either American 1/2A with 049's or the more docile ones for 1.5cc diesels. Just buy them off the rack from Viko etc.

Maris Dislers

Active member

Found scaled down version of Vernon's Zinger, it is in December 1978 Aero Modeller. The photos are light but you should make them out.

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Thanks for the replies, Steve, Mart,Maris, and Joe for the scan.
That is the one I remember, although I'd mistakenly thought the wing was more elliptical. (I was thinking of buiding a " SuperBoomerang" shape with modern construction methods when I remembered Zinger)

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This is a complicated subject.
Just about every vintage combat model uses a flat wing section, aside from ease of building (I cut my ribs as 1" strips and razor-plane the back when the airframe if glued together), it also helps make the model flyable:
With a short hinge line, once you have got the C of G back far enough to make the model turn, the model is fairly unstable (because of the lack of leverage the elevator has, the of C of G has to be rearward). If you think about the arc the tail has to move through to give (let's say) a 45 deg change in attitude, you will see that a Warlord for example has to move through a very small arc compared to a Peacemaker (which has a very long hinge line). When the model turns, broadly speaking, it rotates about a point somewhere between the C of G and the centre of lift, the flat plane wing section moves the centre of lift rearwards thus introducing a stabilising effect. With a long hinge line the tail/elevator creates a natural stability and a 'normal' airfoil section can be used.
In a nutshell; a short hinge line model has to be unstable to turn because of the lack of leverage the elevator has, the flat plate wing section introduces an element of stability by moving the centre of lift away from the C of G.

Mike

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Mart, how do you radius the L / E on the partially assembled wing ? (as I intend to build my next using that type of method)