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Jan 20, 2024 14:33:14 GMT
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Back to the diffuser. The angle of a diffuser shouldn't really exceed 10-12 deg otherwise you can get flow separation as the air can't handle the steep angle. However, using VGs you can encourage the air to stick to the plan, well, that's the theory anyway. Managed to stick these on the right way round first attempt :-) Made a guide so I could easily set the VGs to 15 deg away from the direction of flow.
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Last Edit: Jan 20, 2024 14:34:05 GMT by nalesutol
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Jan 19, 2024 17:51:33 GMT
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Phew! The inclement weather has one saving grace, it delayed the curing of the glue long enough for me to be able to prise them off and reset to the correct orientation. One of them was actually set at the wrong angle so I was able to rectify that. Reminds me of my Teachers' end of term reports - Must try harder!
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Jan 19, 2024 17:24:51 GMT
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Basically finished. It wouldn't get me a job on an F1 composites team but, hopefully, it will be functional. The light spray of black paint has highlighted some areas of adhesive overspread, but that can be easily removed. On reviewing these photos I have just realised that I have stuck the VGs on the wrong way round. Uck it!
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Last Edit: Jan 19, 2024 18:08:09 GMT by nalesutol
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Jan 19, 2024 14:55:59 GMT
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Friends have often laughed at the stuff Julia and I keep/store, "it might be useful one day" I collect metal tubes and sheet in steel and aluminium along with anything that looks like it may be useful at some time. Julia hoards construction materials; bricks, slabs, sand, ballast, etc. Over the years this has been very useful to us and many of our laughing friends. With the temperature down in the low single figures (Celsius for our American cousins) in my garage, even with a couple of heaters going, the adhesive I am using to secure the strakes is very viscous so a pain to mix and spread. I solved the viscous issue but at these temperatures is was taking an age to set enough to hold the curved sections of the strakes in place. I then thought about Julia's store. There were some engineering bricks that are very heavy, ideal for hold strakes in place rather than my hands - they don't get bored or cramp
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Last Edit: Jan 19, 2024 20:16:21 GMT by nalesutol
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Jan 18, 2024 21:02:51 GMT
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Well, that's the outer and straight sections done, now for the awkward bits. I will probably have to result to my usual method of simply holding stuff in place until glue sets, around 7-10 minutes for this adhesive. Decided to leave out the centre strake as it isn't doing a lot other than adding weight.
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Jan 18, 2024 13:33:21 GMT
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You can never have too many clamps. However, the inner strakes will be more of a challenge.
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Jan 18, 2024 11:53:24 GMT
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I haven't bought any carbon fibre cloth for at least 10 years. I got enough to make a whole one piece body back when that was the plan, but plans change and I discovered prepreg. I found a supplier that was prepared to sell me their end of rolls/close to best by date stuff for a very good price so have been using that. Run out and nothing is available at the moment so back to using cloth and resin, Ugh but needs must and I have it. I was on the Easycomposites site yesterday stocking up on bits and pieces (structural adhesive, vacuum bag tubes, demoulding wedges etc) and noticed that they had some unidirectional carbon cloth in their Wholesale Offers section. This stuff is very good at adding stiffness in one direction when used as an intermediate layer. Priced at £11.50/m2 this is around half price so I bought a couple of metres just in case :-)
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Last Edit: Jan 18, 2024 13:32:58 GMT by nalesutol
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Jan 17, 2024 17:26:18 GMT
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Finally, a filler that actually fills! It is light grey, the overhead infrared heater is adding the pink tinge.
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Jan 17, 2024 17:26:00 GMT
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Jan 17, 2024 14:29:35 GMT
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You did get the special hardener for ti didn't you? You can't use std hardener. The ratio is different for ti as well, just follow the tech sheet. 1.5mm is fine, it may need a little thinning as well. They came as a matched pair and tie in with the tech sheet. Any spray paint thinners?
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You would be better to just key the paint and shoot some high build primer over the lot, gloss will always show the scratches. I would recommend Lechlar Green ti high build, lovely stuff. Shoot it over with a large nozzle gun and then flat it back with 800 grit paper. Right, mixing ratios with the Lechler Green TI filler. I have 2.5l of filler and 0.5l of HS hardener. Looking at the TDS is seems to say 1000ml of filler to 200ml of hardener, which looks correct based on the amounts I have. Would you go with this? I have a 1.5 spray gun nozzle, big enough?
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Last Edit: Jan 17, 2024 10:14:18 GMT by nalesutol
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High build primer arrived today so I will experiment on the passenger seat. Son Alex printed the prototype fastener cover, now just need the 1/4 turn fasteners to arrive from China.
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Last Edit: Jan 17, 2024 0:38:33 GMT by nalesutol
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I remember seeing pictures of one (or more) of Don Garlitts top fuelers with those flush wheel discs on the rear wheels and he was a very canny racer! Definitely help with streamlining, which is why you see them on the salt. Not sure they would look right on an Elan though. However, if they proved to be the difference between a 9.00 and an 8.99 then they go on :-)
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Jan 15, 2024 17:53:41 GMT
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Decided on the design and marked it out. Just noticed that I left one piece of masking tape on - third from right in second photo. Cut strakes to length. The eagle eyed amongst you will have noticed that there is one missing. That is curing in the oven as I post this. Basically the last of my prepreg. Until more is available I will make some strakes using wet layup. The comparison will be interesting and educational for me, especially regarding the weight difference as the prepreg should be lighter due to the optimisation of the cloth to resin ratio which isn't possible for us mere mortals. Resin infusion would get you closer but not all the way.
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Last Edit: Jan 15, 2024 18:22:12 GMT by nalesutol
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Jan 15, 2024 14:20:19 GMT
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Started on underfloor aero strake design. No wind tunnel or CFD, just read a lot and get confused then do what looks right to me :-)
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Jan 14, 2024 12:49:49 GMT
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A lot of the salt flats racers use these flush discs. I don't know if it's the spokes or the inset face that hinders air flow. Both I would think, anything that disturbs the airflow has an affect, both positive and negative depending on what you are trying to achieve. The salt look very wet, just tlike the 3 times I have been there. Yet to see any action :-(
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Last Edit: Jan 14, 2024 12:51:07 GMT by nalesutol
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Jan 14, 2024 12:47:58 GMT
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Thanks for that. Downloaded file into Excel and it looks very useful, saves me a lot of work. The author admits that there are errors in his method of calculating Cd and Crr but I am more interested in the real world effects so I will ignore that part. Simple carboard rear arch covers will work for testing. If there is a measurable improvement then serious consideration will have to be undertaken on how best to make and fit them for racing. I love this site and the great people on it. Feedback (positive and negative) is great as long as you have an open mind and accept that you can be wrong and can't think of everything. Accepting that I am wrong will be hard :-)
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Last Edit: Jan 14, 2024 13:09:47 GMT by nalesutol
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Jan 14, 2024 10:20:26 GMT
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Something like this? I know, what wheels? :-) Haven't got wheels yet and this type is on the list, not sure whether they will suit the car though.
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Last Edit: Jan 14, 2024 12:14:22 GMT by nalesutol
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Jan 13, 2024 23:56:21 GMT
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Wheel spats!, that's what they are called :-)
Or fender skirts.
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Last Edit: Jan 14, 2024 0:03:34 GMT by nalesutol
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Jan 13, 2024 23:53:14 GMT
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Yes, similar to that. Meant to be a big help aerodynamically AFAIK. The only reason most race cars don't have them would be to change wheels easily I would think. I have to admit that this isn't something that I have considered but, as you say, they can have an effect on aero. It wouldn't be easy as they would have to be easily removable but very secure to stay on at 150mph+ Something to think about whilst in bed :-)
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