Stefan's Safari VLA (700kg-750kg) build progress - ZU-FMF

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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by Jean Crous » Sat Nov 15, 2014 9:08 pm

=D> =D> =D> =D> Well done Stefan !
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by stefan » Wed Nov 19, 2014 6:13 pm

Today's negative test up to limit loads went Ok and we passed limit load with ease. We loaded both wings to 580kg which represents point F on the Vn diagram. (700kg @ -1,9g)

At Ultimate load (700kg x -1,9 + 150%) we got to 705kg which is 120kg before the required load of 824kg and the right wing rear liftstrut buckled. The left lift strut did not show any signs of buckling or deformation even with the jig being thrown around due to the failure of the R/hand strut. This tells us something. The most likely cause is a defect in the material. We discussed this with CAA and one option is just to re-do the test with new struts and hope all is Ok and we pass 2. Is to lower the MTOW of the plane to the weight passed (don't want to do that either) or 3. Beef up the strut. We decided that it would make sense to rather beef up the strut as this will eliminate any possible flaws in materials for the future by having an additional design safety factor.

From Mike's calculations:
Pcr = π2EI/L2 where Pcr is the critical column load (causing buckling failure), E is the Modulus of Elasticity of the material, I is the area Moment of Inertia of the column and L is the length of the column. A look at this shows that, for our case, E and L are constant. The only variable is I, the area Moment of Inertia. You’re considering increasing wall thickness from 1.2 mm to 1.6 mm while holding the O.D. constant at 1”. This would result in an increase in I of 27% and, therefore, an increase in the critical load of 27%. The strut failed at an applied load of approx. 705 kg. Multiplying by 1.27 gives a Pcr of 895 kg which is more than the scheduled Ultimate load of 824 kg.

We will re-do the ultimate negative load next week Tuesday with the upgraded struts. Nearly there.
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by stefan » Sat Dec 06, 2014 6:23 pm

We upgraded the struts a bit and re-tested on Friday - 04/12/2014 We passed with flying colours =D> =D> =D>
And for those wondering about the trestle under the wing, it is not touching the wing CAA made very sure of that. The trestle was there as a safety so if it breakes we don't bring down the house by bending the hangar beam.
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by Jean Crous » Sat Dec 06, 2014 10:11 pm

:D Well done Stefan, it sure is a comforting thought that you guys take your product quality seriously , and thereby also the safety of your clients.
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by stefan » Wed Dec 10, 2014 6:49 am

Now we can progress to the next phase. The Vertical tail, Horizontal tail, Fuselage, Engine mounts and Landing gear are next. We are preparing the test rigs for them so we hope to be done by mid to end of Jan 2015 with all the structural test.
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by stefan » Tue Feb 24, 2015 9:25 pm

We completed most of the Tail load tests today. All upright test are completed we will do the Upside sown tests on Thursday. Will post pics when I have time to reduce the size
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by stefan » Fri Mar 13, 2015 6:02 pm

All tail load tests completed successful. Now for the deadweight items.
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by stefan » Thu Oct 08, 2015 7:42 pm

All structural testing now completed in accordance with CS-VLA specs and signed off by the SACAA. Now for the last stretch. Flight testing.
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by Jean Crous » Sun Oct 11, 2015 12:15 pm

stefan wrote:All structural testing now completed in accordance with CS-VLA specs and signed off by the SACAA. Now for the last stretch. Flight testing.
=D> =D> =D> Mooi man, go for it !!
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Re: Stefan's Safari VLA (700kg-750kg) build progress - ZU-FM

Unread post by stefan » Fri Nov 20, 2015 9:00 pm

We had a Dutch Engineer here visiting the factory for 2 weeks to assess the Safari and paper work for our Dutch amateur build approval. All is on track, we had to re-do one braked roll test but we did that with him witnessing and we passed with flying colours. We have some minor paperwork to submit and the first 2 Dutch aircraft will leave in December.

We started some certification flight testing a while ago and we are spending a significant amount of time on developing a calibrated pitot static system. We will probably be one of the very few LSA/VLA aircraft that will be able to claim that. We are trying to get our pitot/static error as close to zero as we possibly can so what you see on the ASI is as close to CAS as you can get. This takes a lot of time and fiddling and the weather is also not playing along. The greatest error is at the low speeds at the moment (as with most other aircraft)

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