Olly P Posted January 24, 2011 Share Posted January 24, 2011 Evening all, from a small hotel room in Italy. I've decided to use some of the dark evenings here to think about/plan bits of my Zveno project. I'm currently thinking about the fighter release mechanism, and tring to decide how to rig it for the best safety. If you haven't heard me rabbiting on about it so for then: the Zveno project was a series of combat composites developed in the USSR starting in the interwar period, these consisted (mainly) of heavy bombers with parasite fighters, which could detach and act as escorts or dive bombers. The version I'm going to try and model consists of a pair of IL16's underslung on the wings of a TB-3. I eventually want to set it up so that the IL16's can be released on a Tx switch command, initially however I plan to install the inernal structure for the parasites, then get used to the TB-3 before altering her and adding the IL16's. When I add the IL16's there are several means of attachment, the main distinction being a mechanical attachement or an electro-mechanical attachment. With either system I plan for a seperate power supply to that used for any of the 4 motors, of the Rx/Servo's. I do however need to decide if the power failure mode will be to seperate the fighters, leaving the bomber alone for me to bring in, or to keep them attached for me to bring the entire circus in, and attempt to land it. The 2 fighters will, initially at least, be free flight, and set up to perform a gradual curved descent from release, in opposing spirals. any idea's folks, which way is safer? (I do have my own opinion but want some oothers too...) Thanks Olly. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted January 24, 2011 Share Posted January 24, 2011 Sounds a great ambitious project Olly. You are to be applauded for even considering it all. I would think your biggest problem would be caused during an intentional or a failsafe release if one of the fighters "hung up" while the other one got away OK. So if it could all be landed together, that seems to reduce the possibility of a one sided hang up at least. Edited By Chris Bott on 24/01/2011 22:21:47 Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 24, 2011 Share Posted January 24, 2011 Mmmm, what an interesting question! There are so many factors to consider. If you have an inflight problem with the TB-3. I would guess your first instinct would be to release the fighters and land the TB-3. But the nature of the problem may mean that you cannot release the fighters - i.e. the problem may be affecting the release mechanism. So I would say you need to engineer things so that the TB-3 can land with the fighters attached. Now the TB-3 presumably took off with the fighters so it should be able to land with them - albeit with some difficulty. One thing I would consider is attaching the figthers by a system that operates in parallel and putting a few elements as possible between the two sets of releases. That way you increase the likelihood either both will fail together - or neither will. Either way you end up with an "even ship" so to speak! BEB Quote Link to comment Share on other sites More sharing options...
Olly P Posted January 25, 2011 Author Share Posted January 25, 2011 indeed BEB - I fell asleep thinking on it last night, and quickly, while about to go for breakfast (time is money!). I still want independant power to the release mechanisms, from the flight power. I would think that landing with them attached in the event of a problem is safer (overall) as you only have 1 lump of balsa in the air, not 3, and hopefully I will have some control over it. I'm thinking of using a magnetic attachement system, with a pulse of local EM from coils on the struts to push the fighters off, and away.... Obviously on the real deal the fail safe was having the fighter pilots control the release of the fighters - ensuring, for example, conciousness at the point of seperation... Olly Quote Link to comment Share on other sites More sharing options...
Klippy Posted January 25, 2011 Share Posted January 25, 2011 Just found this thread Olly. As I was reading I immediately thought, hatch magnets, they're amazingly strong, put a small coil around one side,p of the pair, pulse it in opposition, and away she drops. I think you've zeroed in on the right way to do it. It doesn't have to be magnets of course, you could use a Heli type ball link fitting into a piece of tube. Cut two slots in the tube and push a 'U' pin in the slots to lock the ball. I'd be tempted to use a 9gm servo to pull the pin, probably lighter than a home made solenoid. Quote Link to comment Share on other sites More sharing options...
Olly P Posted January 25, 2011 Author Share Posted January 25, 2011 Tony, I wouldn't use a home made solenoid I'd acquire one from work... I will probably conceal it in a representation of the catches used on the real thing. right, tonights fun will be working out which Ashlok conncectors I'm likely to need on each wing, 2 motors (but independant batteries (ish)), servos for ailerons and release mechs...... But that's after a day .with a customer....ciao! Quote Link to comment Share on other sites More sharing options...
Olly P Posted January 25, 2011 Author Share Posted January 25, 2011 Right, doing some serious connector planning now, and have stumbled accross a fairly important question - did the TB3 have a retractable undercarrage? From the photo's I've found I don't think so, anyone know for certain? Quote Link to comment Share on other sites More sharing options...
Eck Posted January 25, 2011 Share Posted January 25, 2011 Looks like a fixed undercarriage to me, mate!http://wp.scn.ru/en/ww15/b/660/1/1 Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 25, 2011 Share Posted January 25, 2011 Cor, what a brute! (Sorry Olly, I forgot - I'm talking of the love of your life!) but I mean to say - its certainly - err....different, isn't it. Yeah I'd say that undercarriage was fixed. Tell me where the engines steam or diesel? BEB Quote Link to comment Share on other sites More sharing options...
Olly P Posted January 26, 2011 Author Share Posted January 26, 2011 BEB - LOL I just find it an interesting piece, and find some of the stranger concepts tried during the interwar period are rarely modelled. the fact that the Zveno SPB was used so successfully during WW2 shows that this was a viable concept, before jet engines and so forth.... Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 26, 2011 Share Posted January 26, 2011 Oh yeah, I mean seriously I'm all for unusual prototypes - adds variety. And at least you can go down to the field and know the guy next to you isn't going to turn up with its twin brother! BEB Quote Link to comment Share on other sites More sharing options...
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