1/3.3 scale Ventus 3 - RC Groups
Thread Tools
Oct 20, 2017, 10:41 PM
Horizon Hobby Team Member
sruelle's Avatar
Build Log

1/3.3 scale Ventus 3


This is in 2015 that this built really started,

Beautiful afternoon, 2 second on not paying attention while circling low, stall in the direction of the tree line and ...CONTACT of the light wood with the hard wood!

This has been the end of the short life of my Discus 2B 4.54m from Graupner. One of the sailplane I have looked for adding to my fleet, built and lost the same year...







After inspecting the plane, wings are a total but fuse and tail are actually in very good shape.

Thank to Dennis (S2000) I have been able to get two canopies he had as spare, as mine shattered during the encounte , the idea of a phoenix already bubbled in my mind...

During end of last year after healing the lost I contacted Schempp Hirth about their ventus 3 and they have been kind enough to send me the 3 views of the beast. Great way to recycle my discus 2B in a ventus 3 FES



Kind of a nice building challenge with the swep of the panels and dihedrals, quite a lot to think and to prepare while my Janus is not even completed (http://forum.scalesoaring.com/forum/...o-janus-nimbus)

I guess I like to have couple projects in the work so I can swap from one to another when the mojo is going down...

That will be a slow build project so be patient
Sign up now
to remove ads between posts
Oct 21, 2017, 09:22 PM
Horizon Hobby Team Member
sruelle's Avatar
First after building a CNC foam cutter, has been to cut these cores.

I decide to build in the dihedral of first and second panel in the foam block, and do the same for third and forth panel. Both will be joined with a CF or Glass wing joiner.

Luckily, the 2in foam block is just enough to host the 2.5 degree dihedral on the first panel and the 7.5 degree dihedral between #3 and 4.

I picked some 2#/cft, I like the dense foam as it really let you performing nice cut and don't compress in the vaccum bag

Here testing the cutting with dihedral



here we go



I integrated some slot for some carbon fiber spar caps




Here checking on the alignment between the panel




Here is a view of the external panel with built in dihedral



The main panel



And the wing shape



Stéphane
Oct 24, 2017, 04:38 AM
Registered User
This looks promising.
Oct 24, 2017, 01:11 PM
Registered User
pete914's Avatar
Sub'd. Very nice!!! Good luck, can't wait to see it flying in Cumberland
Oct 29, 2017, 12:18 PM
Horizon Hobby Team Member
sruelle's Avatar
I pre-cut the veneer and noticed some serious curling and when the veneer was laid down some wrinkles where present.



Something had to be done, I looked on the veneer website and found a recipe to relax the grain of the wood,

4 parts of water, 2 parts of glycerin and one part of alcohol, mix vigorously and spray on wood grain to relax the fibers. Look at the difference between botom sheet that have been sprayed and the top one that are still dry



I put the veneer under some wood plank with some weight on it overnight and the result is pretty good, just need to evaporate the water, should take 48h before using for bagging



Magic!

Stéphane
Oct 29, 2017, 02:46 PM
Registered User
Smyk's Avatar
"4 parts of water, 2 parts of glycerin and one part of alcohol

Magic! "

Stephane

You got yourself involved in some kind of voodoo

I have mentioned it in several posts like this to apply mist of 70% Isopropyl Alcohol ( rubbing) or denatured alcohol just before applying the epoxy on opposite side of the veneer
Alcohol will evaporate before you finish the epoxying the wood leaving small amount of the moisture. Alcohol is hygroscopic too.
Epoxy will accept small amount of moisture and small amount of alcohol vapors, but would not accept glycerin.

What you have done right now you have eliminated long-wise bow, but stocked the wood for not uniform drying. As long the wood is still wet is flexible. As soon drys up really good will show different pattern of dis-formation going alongside of the grain which is much harder to deal with. Been there, done that.

The bottom line is:
Wood has to be slightly moist (not wet) to go inside the bag, can not be super dry.
Plain water is overkill, alcohol with its hygroscopic ability brings the moist of the wood to the acceptable level

Mike

I am never afraid of the bow of the venner
Much worse is when wood shows cross grain waviness
Last edited by Smyk; Oct 29, 2017 at 03:00 PM.
Oct 29, 2017, 03:15 PM
Horizon Hobby Team Member
sruelle's Avatar
Mike

I am sure there is more than one solution to this matter, the advantage of the glycerin to my taste is that once the wood is pressed flat it stay flat. I did it mainly for the wrinkles that appear when you lay the wood flat, not to fight against the curling aspect, the vacuum would be plenty to fight this.

I am not afraid of Glycerin, at it is as the wood it self (cellulose) a long chain alcohol, making the glycerin penetrating the wood grain and not staying as a layer on wood grain.

The epoxy will glue by penetrating the pores of the wood grain as the vacuum will pull it through the wood , like a matrix, so bounding should not be an issue there.

Will keep you posted
Oct 29, 2017, 07:41 PM
Registered User
Smyk's Avatar
Interesting experiment then
I am watching it closely

PM on the making

Mike
Oct 29, 2017, 10:08 PM
Horizon Hobby Team Member
sruelle's Avatar
Next is prep work...

Trimming veneer, cutting fiberglass cloth, cutting peel ply for hinges






One that is done,

Tracing the positioning of the hinges.



securing the peel ply on the bottom of the core to ensure perfect gluing of the lower skin,
Securing the core on the bottom bed for them not to move,



Then wait for the moment to bag in order to cut the carbon spar cap as they will fray quite easily... and bag!
Nov 19, 2017, 09:46 AM
Horizon Hobby Team Member
sruelle's Avatar
Here we go, in between two European trips lets bag the right tip

First lets cut the spar caps out of carbon fiber cloth

Sans titre by steffruelle, sur Flickr

Then lay up fiberglass on the veneer, ratio of epoxy to fiberglass is 1:1 by weight

Sans titre by steffruelle, sur Flickr

Sans titre by steffruelle, sur Flickr

Then flip it on the cores and tape to avoid it to move in the bag

Sans titre by steffruelle, sur Flickr

after closing the bag and pulling vacuum

Sans titre by steffruelle, sur Flickr

Finally Blanket for a sweet curing

Sans titre by steffruelle, sur Flickr


​​​​​​​Bag opening tomorrow..
Nov 19, 2017, 09:09 PM
Registered User
Jets:)'s Avatar
Nice work. Im watching with interest.

What wing sections are you using across the span?
Nov 19, 2017, 09:17 PM
Horizon Hobby Team Member
sruelle's Avatar
Quote:
Originally Posted by Jets:)
Nice work. Im watching with interest.

What wing sections are you using across the span?
I have used the above :

HQ3/13 to HQ3/12 on first panel, then HQ3/12, last panel HQ3/12 to HQ3/11

I have been very happy with the Discus 2B wings, the ventus 3 should be great too
Nov 23, 2017, 04:09 PM
Horizon Hobby Team Member
sruelle's Avatar
Both external panel upper surfaces have been completed, just pulled the left panel out of the bag.

Sans titre by steffruelle, sur Flickr

Sans titre by steffruelle, sur Flickr

Sans titre by steffruelle, sur Flickr

Now, I will carry on with the inner panels before working on spar and wing joiners on the four panels at the same time.
Dec 03, 2017, 09:10 PM
Horizon Hobby Team Member
sruelle's Avatar
Right inner panel turn after my return from Europe

Same principle, two layers of carbon cloth (6oz) 2 in wide for the spar caps and two layers of FG (2.3Oz) for the veneer

Sans titre by steffruelle, sur Flickr


Flap 1 will be hinged from top, you can see this one pretty clear on this picture and Flap 1 will be hinged from the bottom to allow more deflection

Sans titre by steffruelle, sur Flickr

Vacuum

Sans titre by steffruelle, sur Flickr

Blanket

​​​​​​​Sans titre by steffruelle, sur Flickr

Stéphane
Dec 09, 2017, 10:33 AM
Horizon Hobby Team Member
sruelle's Avatar
Left wing in the work... or in the bag should I say

What else to do than building when it is snowing outside

Sans titre by steffruelle, sur Flickr

Sans titre by steffruelle, sur Flickr


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Yippee! First Flight 1/3 Scale Ventus 2ax Mac37 Scale Sailplanes 7 Jan 23, 2012 08:00 PM
Help! Wanted: 1:3 scale Ventus or Discus fuselage yyz Scale Sailplanes 7 Apr 22, 2010 12:58 PM
Build Log Scratch Built composite 1/3 scale Ventus eschlitzkus Scale Sailplanes 25 Oct 28, 2009 08:02 PM
Discussion 6 meter 1/3 scale LET Ventus 2cx s2000 Scale Sailplanes 21 Jun 08, 2009 08:12 AM
Question Opinions on HF Modell 1/3 scale Ventus 2ax? surfimp Scale Sailplanes 6 Feb 19, 2006 12:30 PM