Peter Wood 4 Posted February 7, 2011 Share Posted February 7, 2011 I have nearly completed the airframe of a Precedent Stampe which I purchased with the fuselage and cabanes already built. Before covering I want to check that everything is correctly aligned. Does anybody know what the incidence of the wings and tailplane ought to be? They do not appear on the plans. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted February 7, 2011 Share Posted February 7, 2011 Hi Peter, I don't know about this specific model but I can give you some general observations on incidence in biplanes if that's of any use. The most common set up for aerobatic biplanes is probably 0,0,0 - i.e. zero incidence on the stab and both wings. Another popular set up is 0 on the stab and lower wing, with -1 (or at most -2) on the upper. Both these set up are popular because they tend to help the model in inverted flight and reduce drag. They also tend to reduce the pitch up effect you can get under full power with biplanes. Now having said all that there is a strong school of thought which goes with set ups like; -2 on the stab, 0 on the lower wing and +1 or +2 on the upper wing. The theory here is that this way the upper wing will stall first and that this is desirable because if the lower wing stalls first the model can be pushed into an even more nose up attitude that deepens the stall and can lead to problems. To be honest I've never really got on with sort of set up - but I have seen it work well for other people. So, to summarise, you will find folks out there that favour negative upper wing incidence, positive upper wing incidence, no upper wing incidence, zero stab incidence or negative stab incidence - take your pick! What to do if you can't find the figures? Personally I favour either 0,0,0 or 0,0,-1 / -2 i.e. zero on everything - (which I use on my Pitts Special), or zero stab and lower wing with a small negative incidence on the upper wing - (which I use on both my Tiger Moths). If you are stuck for data - I'd try it at 0,0,0 and see how it flies - it wont be dangerous in that set up. Then change to a small negative upper wing and see how that feels and which you like best. [That way you'll learn a lot about biplane wing incidence as well. Provided you don't go mad and have 5-6 degree differences in incidence you can't really go far wrong. But the model will feel different in different set ups - see which one you like.] Note: all this is assuming you have no engine downthrust! If you do the situation is a bit different. So if you have - say -3 degrees of engine down thrust I'd look at something like +2 degrees lower wing and +1 upper (still keeping the upper wing at a slightly lower incidence but off setting the whole thing to balance the down thrust). This really is "suck it and see territory. What will happen now of course is someone who is an "upper wing stalling first" devotee will post saying the exact opposite BEB Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted February 7, 2011 Share Posted February 7, 2011 Hi Peter,I have just completed a build of a bi plane called Joshephin from an old plan. The angles given are o, o, -3. the -3 is for the top wing. Text on the plan states that the -3 figure is very important...Problem is due to the weather I have yet to maiden her.So really I am not a lot of help to you at the moment. Cheers Quote Link to comment Share on other sites More sharing options...
Peter Wood 4 Posted February 8, 2011 Author Share Posted February 8, 2011 Thanks Fly Boy and Biggles for your comprehensive reply. I have just measured the current incidences. Using the top longeron as datum 0 ie setting the fuselage level along this longeron I get Stabiliser +2 1/2 degrees Top Wing +4 1/2 degrees Bottom Wing + 5 1/2 degrees Engine 0 The stabiliser is obviously intended to be at this angle relative to the fuselage datum, as the tail is seated on a wedge. I assume therefore that the model is designed to fly slightly nose down giving some engine down thrust. So with the tail at 0 degrees the incidences become Top wing +2 degrees Bottom wing +3 degrees Engine 2 1/2 degrees downthrust These figures don't seem too far from your suggestions for a plane with engine downthrust. I will probably stick with them, particularly since I don't envisage flying it inverted for extended periods. Peter Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted February 8, 2011 Share Posted February 8, 2011 OK, seems reasonable. Try her out and see how she feels. BEB Quote Link to comment Share on other sites More sharing options...
bert baker Posted February 19, 2011 Share Posted February 19, 2011 Hi I have had a look at the instructions I have got for the Precedent Stampe no mention of wing incidences in manual. Bert Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted February 20, 2011 Share Posted February 20, 2011 Hi Peter,the plan may not give measurements in degrees for incidences, but they may be taken off the plan in inches or mm. I have seen a plan where the incidence of the top wing is taken from the side view leading edge and measured downwards in mms to the datum line on the plan. This may help. Cheers FB3 Hope you can follow my text. Quote Link to comment Share on other sites More sharing options...
Chris Channon Posted February 21, 2011 Share Posted February 21, 2011 Hi Peter, brilliant aeroplane, just building my 3rd !!!! This one has a S C 180 fourstroke, i had to put the tank in the fuz as i had to cut a lot of the engine mounts away to clear the cowl. Re the incidence angles, if built as per plan then you cannot go wrong with the angles, ie the cabane struts are already marked out where to drill and attach the wire cabane and the lower wing has to fit flush with the fuz ( allowing for the centre sheeting ). Any probs with the build then feel free to give me a shout, Regards Chris. Quote Link to comment Share on other sites More sharing options...
bert baker Posted April 5, 2012 Share Posted April 5, 2012 Having sold my trusty old Stampe in a moment of madness I am now in process of resurrecting another old Stampe that has been waiting in the wings. I have measured the wing incidence of the plan and make it all surfaces at zero in relation to them all. They are all + 4 degrees up at front measured from upper side fuselage longron if I have done it accurately. So this agrees with post made by Biggles Elder Brother previously in this thread topic. Hope this helps any one who is looking. I would agree it is a brilliant plane big and bulky but so much fun. Ive got the bug bad for them. I still have an origional kit untouched plus one that has been built but never finished, left to rot in a shed by previous builder so has water marks on it and it looks like it has wood worm. I also have the quarter scale Svenson Stampe Bert Edited By bert baker on 05/04/2012 13:56:32 Quote Link to comment Share on other sites More sharing options...
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