Simon Cunliffe Posted April 10, 2012 Share Posted April 10, 2012 Hi Can anybody tell me what the CoG is for an Algebra 100? Ta Simon Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 11, 2012 Share Posted April 11, 2012 Not directly but we can work it out!! I have an Algebra 100 wing in my shed, been repairing it for a friend. The C of G is not marked on it but I've measured the wing root chord which is a good starting point. The wing section looks like Eppler 205, very popular for gliders of that era, the chord is 235 mm or 9.25 in. C of G is mostly dependent on tail moment arm but an acknowledged good position for the Eppler 205 is 38% of the root chord (rearwards from the leading edge). Using that I make the C of G 89 mm or 3.5 in aft. There is some sweepback of the leading edge and the trailing edge is perpendicular to the fuselage, that would have the effect of moving the designed C of G position slightly aft. I would set the C of G at 3.25 in (82 mm) and give it a hand launch to check that the pitch trim is not a million miles out. I usually get someone else to hand launch untested gliders so that I am immediately on the sticks (it has gone wrong before!!). It should be slightly nose heavy at that setting (on the safe side) but flyable, next thing to do is launch it (bungee?) and settle it into a reasonable trimmed out cruise. Place the model in a short 30 degree dive and let go of the stick, it should try to pull out of the dive as the tailplane trim will be set to hold the nose up against the nose heavy condition. If it carries on diving then the C of G is neutral (would add some noseweight for a thermal soarer) and if the dive steepens then it is tail heavy (land it carefully and add more nose weight!!). Let us know how you get on, cheers. Gary Quote Link to comment Share on other sites More sharing options...
Simon Cunliffe Posted April 11, 2012 Author Share Posted April 11, 2012 Hi Gary Thanks for the information and calculation. I have used a 'Aircraft Centre of Gravity Calculator' which I came across on t'internet and I've got 3.75"... is it possible that your mate (the one whos wing you are repairing) may be able to confirm? It's far to nice to begger up : ) Thanks again Simon Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 11, 2012 Share Posted April 11, 2012 No worries! Funnily enough I spoke to him earlier today, as I suspected he didn't know the C of G position!! If I had the rest of the aeroplane I could work it out better using a dedicated model glider calculator. We're in the ballpark between us though, 3.75" sounds reasonable, would set it slightly further forward meself. I have another friend who is building a 4 metre Algebra, assuming it's the same fuselage and tail the C of G will probably be the same. I know he has the instructions so I'll give him a ping. GB Quote Link to comment Share on other sites More sharing options...
Simon Cunliffe Posted April 12, 2012 Author Share Posted April 12, 2012 Thanks Gary Are you building anything at the moment? I just ask as I've enjoyed reading your previous build threads. Simon Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 12, 2012 Share Posted April 12, 2012 Cheers! Well, I've got a few things on the go in the shed but my hands are full transferring our Tiger Moth to an LAA permit at the moment, the paperwork is awesome!! Err...well....there is the Roger Pullen Medicine Man, a 12 ft wooden glider, one outer wing panel left to build. There's a thread for that on RCG. Then there is a Flair Baronette which just needs covering and some other bits finishing, short thread for that as well. But...I've always fancied a Carl Goldberg Ultimate 10-300 and I got one from eBay, cheap as chips, about a month ago. I lost my Xtra Wot last year and it's a replacement for that. Someone gave me an OS Max 90 FSR (two-stroke from the early 90s) which I think will be perfect for it. I've taken a few photos of the build but it's fairly well covered on the American forums, might post a few piccies on here. Friend with the big Algebra is going to bring the plan to the flying field tonight. GB Quote Link to comment Share on other sites More sharing options...
Andrew Bourne Posted April 12, 2012 Share Posted April 12, 2012 I still have my rolled ply fuselage Algebra 100" and the original plans/drwgs - must date back circa 1990ish. The CofG on the drwg is 96mm from LE at the root. This is where mine is balanced and it still flies beautifully. Regards Andrew Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 12, 2012 Share Posted April 12, 2012 Good stuff! Never had an Algebra, think I was traumatised by a friend in Scotland, lots of swearing and cursing going on while he was trying to fit radio gear in the narrow fuselage! Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 12, 2012 Share Posted April 12, 2012 News from the big Algebra plan is that the C of G is marked on the plan at 'between 37 and 40% of the root chord'. He did mention that the stab has a flat top surface and cambered undersurface, my MPX Fiesta is like that, seemed to be fad of doing it back then, not sure what the theory was behind that feature. GB Quote Link to comment Share on other sites More sharing options...
pete taylor Posted April 12, 2012 Share Posted April 12, 2012 Hi Simon, I've just checked on the plan of the Algebra 2.5m which is the same as the 100 (unless we're talking about the earlier ripmax Algebra 100) and the CG should be 140 -145mm from the wing root trailing edge with a warning from Mr EMP about having it any further back. Cheers, Pete Quote Link to comment Share on other sites More sharing options...
Simon Cunliffe Posted April 12, 2012 Author Share Posted April 12, 2012 As I've only been at this game for around 12 months I can't say for certain but.... I belive it is an EMP Algebra! See my photos! Does it look like a EMP? My gut feeling is that Andrew is right about CoG (only because it concurs with my calculations!). Thanks everyone Simon Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 12, 2012 Share Posted April 12, 2012 Looks like an EMP one to me, the wing I have in the shed has two panels with polyhedral where it looks like yours are single panel. The Algebra range confuses me, the earlier ones were completely different and designed by Sean Bannister (I think!), this is an Algebra 7 sloper snapped at an Ivinghoe nostalgia day: It's possible that they're unrelated and just using the same name? Had a great evening with my Hi-Phase, calm as a mill pond. Cue gratuitous Hi-Phase piccie!! Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted April 12, 2012 Share Posted April 12, 2012 Thanks Gary - I had one of those Algebras many moons ago and always wondered why the more recent ones looked nothing like it. I think I decided I must have been dreaming. A thin ply fus if I remember correctly, narrower along the bottom than the top. Mine met it's demise when lent to a friend, he didn't crash it, he shut it in his boot lid! Quote Link to comment Share on other sites More sharing options...
Simon Cunliffe Posted April 12, 2012 Author Share Posted April 12, 2012 Gratuitous piccie of Hi-Phase is very nice, it looks like a relaxing evening! Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 13, 2012 Share Posted April 13, 2012 The piccie is from two years ago but it was taken at the same place (and light levels!). Yep, there were ply fuselages and glass fibre fuselages but I know nowt else about Algebras! Quote Link to comment Share on other sites More sharing options...
ZigZag Posted April 20, 2012 Share Posted April 20, 2012 I have my original Dick Edmonds ply fuz Algebra 100" glider dating back to 1990 - it has lasted better than the plans, although they are still totally legible if not a little curled and brown . I can confirm the root chord is 235mm and the recommended CoG is as stated above at 140 to 145mm from TE at root or 90 to 95mm from the LE. So, the suggested 95mm or 3.75" from LE is spot on. Enjoy it Simon - mine still flies brilliantly 22 years on. Oh yes, the inverted aerofoil section on tail plane - this was designed to generate negative lift at speed in a dive, causing the tail plane to pull down, thus gently easing the aircraft out of the dive. Quote Link to comment Share on other sites More sharing options...
Gary Binnie Posted April 20, 2012 Share Posted April 20, 2012 Good stuff, that makes sense about the tail, two mysteries solved at once!! Nice to see that there is still a following for these older glider designs, they fascinate me!! GB Quote Link to comment Share on other sites More sharing options...
Hamish Posted April 20, 2012 Share Posted April 20, 2012 I have Algebra's 800 and a 1000. The quirk on the 1000 is that the tail plane's were both made the same resulting in one generating positive lift negated by the other. I sucessfully destroyed the Fuz of the 1000 by my lack of experience and constant hitting tera-firma to hard. This took me on another experience as I made a mould and built a fibreglass fuz, however modified for electric. Superb model to fly but I can confirm an absolute nightmare to get all the gear in. It amazed me the ammount of lead in the noze which I replaced by getting the biggest motor/battery combination but still needing lead. Not going to comment about CoG as I find I adjust to what I find comfortable which must be within those mentioned Quote Link to comment Share on other sites More sharing options...
PatMc Posted April 20, 2012 Share Posted April 20, 2012 Despite the wing decal Im sure that the Algebra in Gary's photo isn't an Algebra 7. It's an original 1975 competition thermal soarer version either from the plan published in RCM&E or the kit produced, I think by Micro Mold, in the 1970's. As far as I'm aware it's the only version with a V tail. The designer, Sean Bannister developed a series of F3B models using the name Algebra up to about version 8. This is Sean at the F3B World Championships held at York IIRC 1987ish. The inverted aerfoil tail was a design feature of the Algebra 2M had nothing to do with being easier to pull out of a dive. The rationale being that since the tailplane would be generating a download in normal flight an inverted airfoil would be more efficient than either a symmetrical or upright aerofoil. The first EMP Algebra was the 2M as designed by Sean, Dick Edmonds developed this but entirely designed the later gliders that bore the Algebra name. Quote Link to comment Share on other sites More sharing options...
Peter Wood Posted July 24, 2012 Share Posted July 24, 2012 Does anyone know we're I can get a glass fus or to buy a rolled ply one. peter Quote Link to comment Share on other sites More sharing options...
FunnyFlyer Posted July 24, 2012 Share Posted July 24, 2012 @PatMc If that was the World Champs in York - it was 1983. My goodness - some "looks" just don't stand the test of time.... Quote Link to comment Share on other sites More sharing options...
PatMc Posted July 24, 2012 Share Posted July 24, 2012 Posted by FunnyFlyer on 24/07/2012 09:36:31: @PatMc If that was the World Champs in York - it was 1983. My goodness - some "looks" just don't stand the test of time.... Model or man ? BTW Sean was & maybe still is a competitive cyclist & I believe was interviewed on TV just before Bradley Wiggins' triumph in the Tour de France. Quote Link to comment Share on other sites More sharing options...
FunnyFlyer Posted July 24, 2012 Share Posted July 24, 2012 The Man - the model is still gorgeous - I had 3! Yes, my brother was a very good time trialer and road racer. He was amazed to see Sean on the cover of one of the modelling mags in the 80s, as he knew Sean as a cyclist. Quote Link to comment Share on other sites More sharing options...
Clive Hall Posted December 17, 2013 Share Posted December 17, 2013 I can give chapter and verse on the Algebra saga. Algebra 8 has a glassfibre fuselage; I made the mould and all Sean Bannister's fuselages. I have his original drawing beside me now. The wing section was Eppler 193. The fuselage manufacture was later handed over to John Hall in Somerset, and he produced the glass fuselages for the various versions of the Algebra 100 series. The fuselages were supplied to Dick Edmonds who manufactured conventional kits which included the fuselage moulding. Quote Link to comment Share on other sites More sharing options...
pete taylor Posted December 17, 2013 Share Posted December 17, 2013 Posted by Sodbuster on 17/12/2013 10:28:00: I can give chapter and verse on the Algebra saga. Algebra 8 has a glassfibre fuselage; I made the mould and all Sean Bannister's fuselages. I have his original drawing beside me now. The wing section was Eppler 193. The fuselage manufacture was later handed over to John Hall in Somerset, and he produced the glass fuselages for the various versions of the Algebra 100 series. The fuselages were supplied to Dick Edmonds who manufactured conventional kits which included the fuselage moulding. As far as I'm aware the EMP Algebras all used a quite different glass fuselage from the original T tail variant. I've got both of them and I'm not aware of any others apart from the ply versions used in both the early Bannister and EMP Algebras respectively. I'd be fascinated to know more though! Quote Link to comment Share on other sites More sharing options...
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