Flyer Posted February 11, 2017 Share Posted February 11, 2017 Evening Guys, Just a quick question as to whether a delta wing will have a different PSS rib profile to a 'standard ' type wing ? Just putting something on the drawing board and would appreciate a little guidance. Cheers Ade Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 11, 2017 Share Posted February 11, 2017 I have no experience in specific PSS but delta wing aerodynamics are heavily influenced by the delta shape. The great root chord and relatively short span makes thinner wing section structurally possible, hence their attraction for trans and super sonic flight. You will almost by definition have substantial surface area, = skin drag, so you might as well use the delta advantage and use a thinner section to reduce the form drag element. My own experience suggests a thinner section (5%?) needs less negative camber (thus less drag) than a thick section to achieve satisfactory longitudinal stability but the CofG position can be quite critical for the best glide performance. I hope this helps. Edited By Simon Chaddock on 11/02/2017 23:52:01 Quote Link to comment Share on other sites More sharing options...
onetenor Posted February 12, 2017 Share Posted February 12, 2017 More importantly I feel a reflex section should be used. More stability and cuts down tip stalling.If you overdo it you can get an undulating flight .A bit like a butterfly sometimes Experiment with some little all balsa chuckies and some blue tack and washers You'll find a flat plate is as good as any section for the most part # Quote Link to comment Share on other sites More sharing options...
onetenor Posted February 12, 2017 Share Posted February 12, 2017 More importantly I feel a reflex section should be used. More stability and cuts down tip stalling.If you overdo it you can get an undulating flight .A bit like a butterfly sometimes Experiment with some little all balsa chuckies and some blue tack and washers You'll find a flat plate is as good as any section for the most part # Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted February 12, 2017 Share Posted February 12, 2017 This rib profile is about 20" long and is about 8% thickness. Edited By Mark Kettle 1 on 12/02/2017 02:36:16 Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted February 12, 2017 Share Posted February 12, 2017 It is interesting One tenor, what you say about the flat plate wing, as my small Aeronautics library goes back to the 1940s, And even then, the benefits of the flat plate wing were highly regarded in modelling, due to their simplicity of construction, their relative stiffness in small scales, and of course, the least weight for the most lift from flat materials. You summed this up well. We see the benefits of flat plate models at every indoor flying event Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted February 12, 2017 Share Posted February 12, 2017 This model fly's very well on a flat plate wing. Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted February 12, 2017 Share Posted February 12, 2017 Maybe you could use a flat plate Flyer? Whats the sharp of ideas? Quote Link to comment Share on other sites More sharing options...
MattyB Posted February 12, 2017 Share Posted February 12, 2017 Ade, be aware that any really sharply tapered delta will not perform that well on the slope, irrelevant of the section used. Soaring performance will be poor compared to a straight or slightly swept wing, and whilst they can be made to go fairly quick in a straight level line inertia tends to be quickly killed in the turn. A Vulcan type platform is about as far as I recommend you can go on the slope unless you have a brick lifter like the Orme as your local slope. If not choose another subject, otherwise your hard work will just deliver you a hangar queen! Quote Link to comment Share on other sites More sharing options...
Flyer Posted February 12, 2017 Author Share Posted February 12, 2017 Posted by MattyB on 12/02/2017 11:58:11: Ade, be aware that any really sharply tapered delta will not perform that well on the slope, irrelevant of the section used. Soaring performance will be poor compared to a straight or slightly swept wing, and whilst they can be made to go fairly quick in a straight level line inertia tends to be quickly killed in the turn. A Vulcan type platform is about as far as I recommend you can go on the slope unless you have a brick lifter like the Orme as your local slope. If not choose another subject, otherwise your hard work will just deliver you a hangar queen! I'm actually looking at a septcat Jaguar 'E' (the two seater) in 1/12th scale. It's bascially a delta wing form, stuck on top of the fuselage. On reflection, the wing area looks similar to the A4 Shyhawk. So I am tending to look in that direction at the moment. Whilst not a true 'delta' I feel it could be influenced by those forces. Cheers Ade Quote Link to comment Share on other sites More sharing options...
Mannyroad Posted February 12, 2017 Share Posted February 12, 2017 Posted by onetenor on 12/02/2017 02:05:30: More importantly I feel a reflex section should be used. Onetenor, can you expalin to me what you mean by a reflex section? # Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted February 12, 2017 Share Posted February 12, 2017 Below looking at the drawn and yellow wing section. Reflexed section - notice how the return to the top line towards the trailing edge is con-caved slightly. Edited By Mark Kettle 1 on 12/02/2017 22:30:09 Edited By Mark Kettle 1 on 12/02/2017 22:31:32 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 12, 2017 Share Posted February 12, 2017 Flyer Whilst a Jaguar has a very low aspect ratio wing the fact that it also has a conventional tail plane means it is acting as a conventional wing not a delta which has to provide it own longitudinal stability. Does a Jaguar have sufficient wing area relative to its body size to be a good PSS? Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted February 12, 2017 Share Posted February 12, 2017 He could cheat and stretch it a bit ? PSS Jaguar here http://www.pssaonline.co.uk/images/487.jpg Edited By Mark Kettle 1 on 12/02/2017 23:09:07 Edited By Mark Kettle 1 on 12/02/2017 23:09:33 Quote Link to comment Share on other sites More sharing options...
Mannyroad Posted February 13, 2017 Share Posted February 13, 2017 Mark, Thanks for that. learned something new. Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted February 13, 2017 Share Posted February 13, 2017 That's ok Mannyroad, the wing section makes it fly like this : Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted February 14, 2017 Share Posted February 14, 2017 The Jag isn't a delta really, and shouldn't be treated as such for wing sections. There is some experience within the PSSA on Jaguars - you might want a quick word with Phil on the front. The profile of the wing is a tricky one to make due to the cranked TE, but whatever you do, I'd build this LIGHT. Quote Link to comment Share on other sites More sharing options...
Flyer Posted February 14, 2017 Author Share Posted February 14, 2017 Posted by Andy Meade on 14/02/2017 09:04:02: The Jag isn't a delta really, and shouldn't be treated as such for wing sections. There is some experience within the PSSA on Jaguars - you might want a quick word with Phil on the front. The profile of the wing is a tricky one to make due to the cranked TE, but whatever you do, I'd build this LIGHT. Cheers Andy, I'll try and have a word with him at Cosford Saturday. But I still think the plan view is very much a delta. But I take your points on board, and a light build should allow a scal(ish) wing. Cheers Ade Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted February 14, 2017 Share Posted February 14, 2017 Well it is nearly triangular in shape, admittedly. Doesn't mean you need a reflex wing section or use elevons though The wing shape is quite similar to the F101 Voodoo too - another one I've drawn up and hope to make at some point in the future Quote Link to comment Share on other sites More sharing options...
Flyer Posted February 14, 2017 Author Share Posted February 14, 2017 Aha, point taken . Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted February 14, 2017 Share Posted February 14, 2017 Get on and draw that plan up - I know there'd be at a couple more pilots interested in one Quote Link to comment Share on other sites More sharing options...
Flyer Posted February 14, 2017 Author Share Posted February 14, 2017 Will get it drawn by The Orme in April ! Also, referring back to the delta wing; would the Gloster Javelin have the characteristics of a delta? I know it's got the high tail, but looking at it, it could benefit from elevons too? And, btw, I've just acquired a 1/48th plastic kit to base a drawing on! So many ideas, so little time. Cheers Ade Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted February 14, 2017 Share Posted February 14, 2017 That seems to be the way of the PSS'er I'm afraid! The Javelin still flies ok with ailerons and separate elevator (see Mick Reeve's BIG turbine version). I think the rule here is that if it has a tailplane of any kind, use elevators. Except if it's a canard, then you can use elevons or aileron / elevator Speaking of which - where's the X29?! Quote Link to comment Share on other sites More sharing options...
Flyer Posted February 14, 2017 Author Share Posted February 14, 2017 It's work in progress; as I'm trying to source a decent plastic kit to get the fuselage right. I've got the two view drawings, but am not happy with the fuselage. Although, I may just use artistic 'licence' and use the 'if it look's right'...... Maybe ready for August PSS meet. Using 1/10th Scale for the X29 just to prove the concept, before I have another FSW in mind. And work has been busy since mid October, so have only managed last weekend to finish off the A4. Hoping to start final spraying once it warms up a little (as I am currently banned from spraying in the conservatory!!). Ade Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted February 14, 2017 Share Posted February 14, 2017 Berkut perhaps? It's been on my bucket list for a while. Maybe one day! Quote Link to comment Share on other sites More sharing options...
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