-
- Administrator
-
-
Before your membership becomes valid, you will receive an email that must be answered.
Please check your spam folder or this email.
Wing joiner location
-
- Posts: 25
- Joined: 09 Jun 2023, 17:50
- Location: Southampton
Wing joiner location
Im converting a design from flat steels to round tube .
The design in question, a airspeed tern has flat steels in between the front and rear spars. Its over engineered and heavy as a result.
Can I locate an alternative single round joiner tube arrangement central in the wing? I will provide suitable reinforcement, although the ribs in question are ply and have incidence pegs.
Should I be placing the joiner over the centre of pressure /cg?
The design in question, a airspeed tern has flat steels in between the front and rear spars. Its over engineered and heavy as a result.
Can I locate an alternative single round joiner tube arrangement central in the wing? I will provide suitable reinforcement, although the ribs in question are ply and have incidence pegs.
Should I be placing the joiner over the centre of pressure /cg?
- chris williams
- Posts: 1574
- Joined: 10 Mar 2015, 10:50
- Location: Blandford Dorset
Re: Wing joiner location
Adam, there was 3.5 scale Petrel at the last WS scale meet which had a moderately heavy landing on the front of the slope. It had been modified from flat steel to a round joiner. The joiner stayed where it was, while wing re-modified itself around the joiner, resulting in a really difficult-looking repair.
A flat steel joiner would have simply bent forwards, allowing the the rubber bands to do their work. How do I know this? I've had more heavy slopeside landing with my various Petrels than I care to talk about...!
A flat steel joiner would have simply bent forwards, allowing the the rubber bands to do their work. How do I know this? I've had more heavy slopeside landing with my various Petrels than I care to talk about...!
- Cliff Evans
- Posts: 1036
- Joined: 29 Dec 2019, 15:13
- Location: Bristol
- Contact:
Re: Wing joiner location
I really would not change the joiner. You do not need to " save waight" the model is proven as it is. Chris's description is very accurate.
https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk
https://patteaklegliders.co.uk
-
- Posts: 25
- Joined: 09 Jun 2023, 17:50
- Location: Southampton
Re: Wing joiner location
Cliff,
It is mighty heavy . Formers alone are 1kg. Massively over engineered . Ive recut lighter ones .
Both blades are 750mm long and again add a lot of weight.
Barry who built one on here recommended it needs lightening after flying it.
It is mighty heavy . Formers alone are 1kg. Massively over engineered . Ive recut lighter ones .
Both blades are 750mm long and again add a lot of weight.
Barry who built one on here recommended it needs lightening after flying it.
-
- Posts: 102
- Joined: 26 Jun 2022, 00:51
- Location: Hampshire
Re: Wing joiner location
Don't do it........
BC
- chris williams
- Posts: 1574
- Joined: 10 Mar 2015, 10:50
- Location: Blandford Dorset
Re: Wing joiner location
What span is the model, and the projected all-up-weight...?
- Trevor
- Posts: 162
- Joined: 19 Jul 2016, 16:29
- Location: Hampshire
- Contact:
Re: Wing joiner location
I'm all in favour of a bit of weight saving but I'd leave the joiners alone and focus on the rear end. Generally the rear fuselage formers are a good target, and I tend to go for balsa skins rather than ply. Tailplane joiner wires often seem rather on the heavy side, unless you are contemplating high speed, high g aerobatics of course.
Each to his own, I suppose,
Trevor
Each to his own, I suppose,
Trevor
Trevor
www.bartonhewsons.uk
www.bartonhewsons.uk
- Cliff Evans
- Posts: 1036
- Joined: 29 Dec 2019, 15:13
- Location: Bristol
- Contact:
Re: Wing joiner location
There is nothing wrong with the weight of the Tern. The models that have been built fly well. I think they have all turned out at around 11-12 lb which is not bad and about average for a 1/4 scale model with a span of 4mtr.
https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk
https://patteaklegliders.co.uk
- chris williams
- Posts: 1574
- Joined: 10 Mar 2015, 10:50
- Location: Blandford Dorset
Re: Wing joiner location
Next question: which depth of blade; 12mm or 15mm...?
-
- Posts: 25
- Joined: 09 Jun 2023, 17:50
- Location: Southampton
Re: Wing joiner location
Weight saving operation has already commenced . 5kg is the target , 1 kg below barrys build.
Overall the drafting quality is a 4/10 when it comes to the formers. Ill end commentary there as this isnt the reason for my query.
Chris, 4m span , taper wing . 15mm steel and brass blades x 2.
The rear spar is on the centre of pressure so maybe a tube can go there instead of a blade with a short blade up front ? Barry friend did the opposite way round and seems to be happy with it.
Overall the drafting quality is a 4/10 when it comes to the formers. Ill end commentary there as this isnt the reason for my query.
Chris, 4m span , taper wing . 15mm steel and brass blades x 2.
The rear spar is on the centre of pressure so maybe a tube can go there instead of a blade with a short blade up front ? Barry friend did the opposite way round and seems to be happy with it.