Bvm F86 Pst J600
05-30-2003, 03:00 AM
#1
Thread Starter
Bvm F86 Pst J600
Hi Guys
Flew my 17.25 lb PST J600 powered BVM F86 today. I am using a JR 410 gyro on rudder / nosewheel.
I found that a couple of clicks of up trim (as the manual suggested ) was needed but that was all to fly straight and level. I do have a quick question though for those that have built and flown the new kit.
I noticed that the Sabre would roll a bit to the left on loops. I checked the incidence of the stabs and alignment as well as pull of each elevator. All appear correct. Any suggestions or pointers would be helpful in perfecting this platform.
Flew my 17.25 lb PST J600 powered BVM F86 today. I am using a JR 410 gyro on rudder / nosewheel.
I found that a couple of clicks of up trim (as the manual suggested ) was needed but that was all to fly straight and level. I do have a quick question though for those that have built and flown the new kit.
I noticed that the Sabre would roll a bit to the left on loops. I checked the incidence of the stabs and alignment as well as pull of each elevator. All appear correct. Any suggestions or pointers would be helpful in perfecting this platform.
05-30-2003, 10:17 AM
#4
Bvm F86 Pst J600
F86 AIRWORTHINESS CAUTION.
My BVM Sabre is ready to test fly at Jets Over Sydney in two weeks time, also with a PST 600 another one of which (an R) powers my little BobCat. A word of caution to all BVM F86 owners : My F86 was being given final checks when a ball link popped off the elevator horn, which could have been fatal in flight. The fix is easy. I have fitted a piece of 1/4 balsa 1 inch by 1/2 on which one surface has an arc in it which is the same as that described by the elevator horn. The arc in the balsa is faced with a strip on of thin polyply and this poly ply concave arc is in very close proximity to the ball link during its travel, so that the link cannot come off the ball. Two of these "cams" are fitted one for each horn and they are glued to the side of the fin base. The link has defied all efforts to dislodge it but if it should need to be removed for any reason just cut away the balsa arc.
Perhaps this may save someone else's Sabre.
Regards,
David Gladwin
My BVM Sabre is ready to test fly at Jets Over Sydney in two weeks time, also with a PST 600 another one of which (an R) powers my little BobCat. A word of caution to all BVM F86 owners : My F86 was being given final checks when a ball link popped off the elevator horn, which could have been fatal in flight. The fix is easy. I have fitted a piece of 1/4 balsa 1 inch by 1/2 on which one surface has an arc in it which is the same as that described by the elevator horn. The arc in the balsa is faced with a strip on of thin polyply and this poly ply concave arc is in very close proximity to the ball link during its travel, so that the link cannot come off the ball. Two of these "cams" are fitted one for each horn and they are glued to the side of the fin base. The link has defied all efforts to dislodge it but if it should need to be removed for any reason just cut away the balsa arc.
Perhaps this may save someone else's Sabre.
Regards,
David Gladwin
05-30-2003, 10:25 AM
#5
Bvm F86 Pst J600
Perhaps I should add that the links were replaced with new during turbine conversion even though the model ahd not flown as a DF.
DG
DG
05-30-2003, 11:57 AM
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Bvm F86 Pst J600
I believe that David does not have the new kit, but it is an old one converted. The new kit, IMO, has an excellent external arrangement for the elevator control rods. They are not a problem.
05-30-2003, 01:33 PM
#8
Thread Starter
Bvm F86 Pst J600
Hi Tony
Nice to hear from you again. I agree that the way BV does the tail in the new kit is much nicer than the old. I had the old version too and can appreciate the improvements in his newest version ( particularly the plug in wings !! ) As far as you can recall - any pointers in getting the Sabre to track straight through a loop. Mine has a tendency to fall off when I begin a steady pull on the elevator. Otherwise she is a dream to fly!
Nice to hear from you again. I agree that the way BV does the tail in the new kit is much nicer than the old. I had the old version too and can appreciate the improvements in his newest version ( particularly the plug in wings !! ) As far as you can recall - any pointers in getting the Sabre to track straight through a loop. Mine has a tendency to fall off when I begin a steady pull on the elevator. Otherwise she is a dream to fly!
05-30-2003, 02:01 PM
#10
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Bvm F86 Pst J600
Originally posted by Helijet
As far as you can recall - any pointers in getting the Sabre to track straight through a loop. Mine has a tendency to fall off when I begin a steady pull on the elevator. Otherwise she is a dream to fly!
As far as you can recall - any pointers in getting the Sabre to track straight through a loop. Mine has a tendency to fall off when I begin a steady pull on the elevator. Otherwise she is a dream to fly!
Rudder trimmed and vert fin straight?
Lateral balance. Got a heavy wingtip?
Flaps tight in up position (drooping flap under G will cause a roll).
Elevators throw the same distance? (not eyeball.. but measured)
No protruding covers/plates on one wing but not the other.
Tony will no doubt go through all this if you call him too.
-Doug
05-30-2003, 08:01 PM
#12
Thread Starter
Bvm F86 Pst J600
Well looks like we may have found the culprit! I build most of my jets myself but from time to time I have contracted a project out. I ALWAYS do my own final rigging though. In this particular case although the basic construction was completed there was little time or effort ( by the builder ) put in doing the final touches that either make a plane just O.K. or great to fly. On receiving her from the builder we had to do a lot of extra work to get things right ( retract actuation, gap alignment, linkage work etc ).
What I did not pay particular attention to was the tight fit that is necessary at the tail. The Sabre tail is fairly complex and the builder needs to ensure that the vertical and horizontal fins are properly aligned, secure and RIGID. I remember from the old BVM and Fibreclassics F86 that if you pushed the design too fast the tail would twist causing some funky roll action particularly during a loop or exiting a split S. Upon closer examination the horizontal stabs although screwed in place on the ply mount had significant vertical component play. Although the upper edge of the root rib was in contact with the face of the fuse there was a significant gap > 1/8 inch underneath. This would allow for some flexing of the stabs. To fix this we applied a polyester filler on the face of the horizontal root rib and secured it back on the fuse. Some wax paper was applied between. Once dry the stabs become considerably stiffer. Although a nice feature I also think I will permanently glue the carbon spars to the fuse ply plate. This way there will be no play at all. The plug in wings are really what makes this plane easier to transport. So...was it the fix?
This afternoon we quickly got out to the field to try her again and guess what..... very straight, round loops. So be sure to spend that little extra time on the tail feathers - make sure that they are aligned, gapless, tight and true and you will have one of the sweetest flying jets out there!
What I did not pay particular attention to was the tight fit that is necessary at the tail. The Sabre tail is fairly complex and the builder needs to ensure that the vertical and horizontal fins are properly aligned, secure and RIGID. I remember from the old BVM and Fibreclassics F86 that if you pushed the design too fast the tail would twist causing some funky roll action particularly during a loop or exiting a split S. Upon closer examination the horizontal stabs although screwed in place on the ply mount had significant vertical component play. Although the upper edge of the root rib was in contact with the face of the fuse there was a significant gap > 1/8 inch underneath. This would allow for some flexing of the stabs. To fix this we applied a polyester filler on the face of the horizontal root rib and secured it back on the fuse. Some wax paper was applied between. Once dry the stabs become considerably stiffer. Although a nice feature I also think I will permanently glue the carbon spars to the fuse ply plate. This way there will be no play at all. The plug in wings are really what makes this plane easier to transport. So...was it the fix?
This afternoon we quickly got out to the field to try her again and guess what..... very straight, round loops. So be sure to spend that little extra time on the tail feathers - make sure that they are aligned, gapless, tight and true and you will have one of the sweetest flying jets out there!
05-30-2003, 09:03 PM
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Bvm F86 Pst J600
Originally posted by David Gladwin
F86 AIRWORTHINESS CAUTION.
My BVM Sabre is ready to test fly at Jets Over Sydney in two weeks time, also with a PST 600 another one of which (an R) powers my little BobCat. A word of caution to all BVM F86 owners : My F86 was being given final checks when a ball link popped off the elevator horn, which could have been fatal in flight. The fix is easy. I have fitted a piece of 1/4 balsa 1 inch by 1/2 on which one surface has an arc in it which is the same as that described by the elevator horn. The arc in the balsa is faced with a strip on of thin polyply and this poly ply concave arc is in very close proximity to the ball link during its travel, so that the link cannot come off the ball. Two of these "cams" are fitted one for each horn and they are glued to the side of the fin base. The link has defied all efforts to dislodge it but if it should need to be removed for any reason just cut away the balsa arc.
Perhaps this may save someone else's Sabre.
Regards,
David Gladwin
F86 AIRWORTHINESS CAUTION.
My BVM Sabre is ready to test fly at Jets Over Sydney in two weeks time, also with a PST 600 another one of which (an R) powers my little BobCat. A word of caution to all BVM F86 owners : My F86 was being given final checks when a ball link popped off the elevator horn, which could have been fatal in flight. The fix is easy. I have fitted a piece of 1/4 balsa 1 inch by 1/2 on which one surface has an arc in it which is the same as that described by the elevator horn. The arc in the balsa is faced with a strip on of thin polyply and this poly ply concave arc is in very close proximity to the ball link during its travel, so that the link cannot come off the ball. Two of these "cams" are fitted one for each horn and they are glued to the side of the fin base. The link has defied all efforts to dislodge it but if it should need to be removed for any reason just cut away the balsa arc.
Perhaps this may save someone else's Sabre.
Regards,
David Gladwin
I have flown my BVM Sabre as a DF for some time and did not have any trouble with the Elevator linkage.
While doing the conversion however, I was trying to get a little more elevator travel and I came accross the problem you described. I am not sure if I have completly solved it but I made a slight bend in the pushrod fork so that the ball links press firmly upwards towards the horns.
Your idea seems to be a bit more posative. I think I will try it.
At least with the turbine conversion you can get at the linkages without destroying the model.
I hope to see yours flying at Temora
Regards
05-30-2003, 11:24 PM
#14
Bvm F86 Pst J600
Yes, My Sabre was an early kit and I would never use ball links again for this critical application; the problem arose when trying to get max elevator throw. Perhaps Dean could tell us the throws he is using and the exact C of G.
Tommy, look forward to seeing you and flying the F86 (and F4, F15 and Bobcat) at Temora, its a superb location.
Regards, David Gladwin
Tommy, look forward to seeing you and flying the F86 (and F4, F15 and Bobcat) at Temora, its a superb location.
Regards, David Gladwin
05-31-2003, 12:49 PM
#15
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Bvm F86 Pst J600
Hi Dean
Way to go !You have so many great looking planes in your hanger,i wouldn't know which one to fly next.Looks to be the year of the Sabre,you can't keep a good plane down.
LOL
Charlie H.
Way to go !You have so many great looking planes in your hanger,i wouldn't know which one to fly next.Looks to be the year of the Sabre,you can't keep a good plane down.
LOL
Charlie H.
05-31-2003, 04:18 PM
#16
Thread Starter
Bvm F86 Pst J600
Yes your right Charlie - way too many toys. The joke up here is
that I have more jets than the Canadian AirFarce does.
David,
I have found the Cg location as indicated on the plans to be the best starting point for both the older version and new one. I balance the plane with the UAT FULL at 9.5 inches aft of the leading edge measured at the root. This allows for very nice rotation on takeoff ( not too much back pressure ) and plently of elevator authority for flare on landing. I have 1 inch up travel on elevators and 5/8 down.
that I have more jets than the Canadian AirFarce does.
David,
I have found the Cg location as indicated on the plans to be the best starting point for both the older version and new one. I balance the plane with the UAT FULL at 9.5 inches aft of the leading edge measured at the root. This allows for very nice rotation on takeoff ( not too much back pressure ) and plently of elevator authority for flare on landing. I have 1 inch up travel on elevators and 5/8 down.
05-31-2003, 05:20 PM
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Dean,They might be right,you having more planes and stick time.
How much aileron throw do you have on the 86 ?I'm using about 3/8" with about 30% expo.
Charlie
How much aileron throw do you have on the 86 ?I'm using about 3/8" with about 30% expo.
Charlie
05-31-2003, 08:41 PM
#18
Thread Starter
Bvm F86 Pst J600
Charlie
I am using no expo on aileron or elevator. I have 25% expo on rudder and I am using a JR 410 gyro coupled to both nose wheel and rudder. She tracks perfectly on takeoff and there is no sign of an dutch rolling in flight - absolutely solid. My aileron throws are 5/8 up and 1/2 ' down. As I recall, I had no expo on my first one either and there is none on the bigger Martin Levebre Sabre.
I am using no expo on aileron or elevator. I have 25% expo on rudder and I am using a JR 410 gyro coupled to both nose wheel and rudder. She tracks perfectly on takeoff and there is no sign of an dutch rolling in flight - absolutely solid. My aileron throws are 5/8 up and 1/2 ' down. As I recall, I had no expo on my first one either and there is none on the bigger Martin Levebre Sabre.
06-01-2003, 10:21 AM
#20
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Bvm F86 Pst J600
Had the maiden flight with my new BVM F86 last week and I have to say it is absolutly supurb.It is quick but lands so slowly.It`s one of those planes that if you crash you have just got to build another!
jason
jason
06-01-2003, 05:17 PM
#21
Bvm F86 Pst J600
Originally posted by Helijet
Yes your right Charlie - way too many toys. The joke up here is
that I have more jets than the Canadian AirFarce does.
Yes your right Charlie - way too many toys. The joke up here is
that I have more jets than the Canadian AirFarce does.
That's not a Joke Dean LOL!!!!! I think I've got more Jets than the Canadian AirFarce does too! LOL, at least operational ones
:rainfro: <------ this guy has nothing to do with my post, but he's kinda kewl I think LOL
Congrats on the F86 flights Dean, I can't wait to see your birds in action!
