FT Saab Viggen 70 mm EDF.

You can be justly proud of that Crash, I hope it flies as good as it looks.

Eric wrote, "My models look like that when they've been in the loft for a while! "

I can certainly see the similarity, the difference is, I don't think you could cultivate mushrooms on mine ! [badass]

The weather is absolute crap at the moment, so no chance of any flying. I spent a lot of the winter getting all the planes I intent to fly this Spring/Summer tidied up. That being finished I was at a bit of a loose end, with the model side of things, so seeing as I have an extra set of plans I decided to revisit the Viggen. The first offering weighs 300 grams more than the flite-test kit, hence a more powerful EDF & reduced flight time. A lot of this is due to the board that i'm using being heavier than their own brand, the rest is down to things such as using a plastic thrust tube & adding LED's for the after burner, which is a lot of extra weight at the wrong end ! I also found that the paper covering on the board is quite heavy, almost like thin card. So the plan for this one is to remove the paper from one side of any internal components, which also makes the folds easier, & use a card thrust tube minus the LED's. It's going to be interesting to see just how much weight I can shave off !

I made a Carlos Reyes model using Architects board which required the cladding to be removed. I never did find a foolproof way to do it but, a black dustbin bag worked well when all the pieces were cut. Soaking overnight in Meths seemed to work as did Scrubbs Ammonia. Use it, don't use it!

I see what you mean Klippy, peeling the Paper/card is tedious & not very efficient !
I did manage to get most of it off where the ridge fits, & the area behind the EDF where the thrust tube goes. I left the ducts alone to keep the surface as smooth as possible. It became obvious that another solution was required. As an experiment I made a copy of the battery box cutout in the extruded foam I had cut down to 5 mm sheet. I can't weigh it at the moment ( scales broke) but even in the hand there is considerable difference, I would guess it weighs 50% less ! Although I can't make the whole airframe with it, It won't fold without splitting, I decided to use it anywhere I can. The battery box, being internal, was a prime candidate. Also the top ridge, covered on the outside with brown paper & diluted wood glue, is far lighter then the original. I may well use the same method on the canards & tail fin, not sure about the wing though, as such a large area of flat plate will be prone to warping , we shall see !
One final problem, I can't find a 70 mm EDF in europe for love nor money !

Here you go Crash...in stock apparently.

Thanks for the thought Paul, that's where the first one came from. Unfortunately since blighty left the European f--k up the taxes + postage on importing from the UK are so high it almost doubles the cost of the fan ! I have two choices, wait for Hobbyking eu to get more stock or order it from china, either of which means a long wait.
On the plus side I went out & bought a new set of scales this morning, the results are interesting. That explains a lot ! Think I had better cut down some more foam ! :whistle:

The next questions are:-
How much weaker is the lighter foam?
Is the strength/stiffness of the foam important for its application?

Quorneng wrote: The next questions are:-
How much weaker is the lighter foam?
Is the strength/stiffness of the foam important for its application?

In it's naked form, quite a bit weaker, but once covered with brown paper & wood glue remarkably strong. The plan is is for the battery box, EDF & thrust tube mounts to be in bare foam as they have plenty of internal support. The tail fin, canards & ridge will be in covered foam. As you can see from the photo I made the tail fin, slotted it & flush fitted a carbon tube with epoxy for extra stiffness. Now covered it is extremely stiff & still weighs considerably less than the original.

That's nice neat work crash!

Work on the Viggen Mk2 progressing slowly, in between building my Granddaughters dining table. Most of the components that can be made using the brown paper covered foam are finished. Still undecided about the wing, but the weight saved already is considerable ! I still can't find the right 70mm EDF anywhere. I even thought about biting the bullet, paying the import duty & ordering from 4Max, but they only have the 6s version. At 2300 Kv, that will lack some RPM when run on 4s. The 4s version is 3300 Kv.
Combined weight of all these parts 58 grams, I estimate that to be a saving of close to 50 % !

Frustrated at the lack of availability of a suitable EDF in Europe, I have ordered exactly the same one that's in the MK1 from Banggood, at under half the price !
At least now it's on the way, albeit by slow boat.

Nice one! I hate waiting for things to arrive

Wonder if your fans now stuck in the Suez canal?

As a backlash from Evergreen getting stuck, are the Canal Authorities going to set a maximum size limit for ships, or insist that these monsters have a fleet of tugs to drag them through, to prevent it happening again - with the resulting transport costs increase?