Twin Eng Thrust Angles
11-18-2002, 05:55 PM
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Twin Eng Thrust Angles
I'm planning on building a 85" B25 this winter from my 3 views and my own drawings. I've never done a twin before. What I'd like to know is what angles (offsettings, downthrust etc) for each eng. Is there a general rule of thumb?
Thanks
Tom
Thanks
Tom
11-18-2002, 10:05 PM
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B-25....
Tommy...You're embarking on quite a project for first twin....B-25 is a complex warbird that has multiple wing dihedrals changing fromI/B wing area to O/B....needs minimum of 2 degrees washout O/B of engine nacelles....stab is "0" incidence and wing is +1 degree incidence....Need minmum of 2 degrees( 3 is better) downthrust per engine and because of big tail and long fuse carries a high wing loading making it difficult if not impossible to fly on one engine....have built several Zirolis and flown 5 or 6 of them.....I would do another twin first but if your "commited" to do this one get lots of help from your local "warbird" group....See thread about "downthrust" opened by JGrc on this page...has invaluable info on this topic from very knowledgable group of guys....Good Luck....Bill......
12-01-2002, 09:08 PM
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Twin Eng Thrust Angles
Hi Tommysta....
I have a d-18 from Ziroli that i am going to build.
114"span with two zenoah 38.
On the drawings Mr Ziroli write.
scale thrust line is 2 degrees out thrust on each engine including
nacelle.
Flight tests have shown that for easier take offs right thrust is required. Reduce left engine to 0-1 degrees of left thrust and increase right engine to 3-4 degrees of right thrust.
This will reduce torque taking the d-18 to the left during take off.
I don't know if this is fore all twins or just fore the d-18.
Hope this was helpful.
Ketil
I have a d-18 from Ziroli that i am going to build.
114"span with two zenoah 38.
On the drawings Mr Ziroli write.
scale thrust line is 2 degrees out thrust on each engine including
nacelle.
Flight tests have shown that for easier take offs right thrust is required. Reduce left engine to 0-1 degrees of left thrust and increase right engine to 3-4 degrees of right thrust.
This will reduce torque taking the d-18 to the left during take off.
I don't know if this is fore all twins or just fore the d-18.
Hope this was helpful.
Ketil
