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Author Topic: Peck Peanut Pietenpol G-24 powered  (Read 2429 times)
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Jack Plane
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« Reply #50 on: March 20, 2017, 03:09:33 AM »

Too much down thrust can really be hard to spot. When you gave the figures I was a little surprised. My Comper only has about 2 deg down and about 3 deg right side thrust, with left rudder to control the left turn. The initial run is straight and as the airspeed reaches a critical point you can see the the rudder kick in.

Also I recently added a Gurney strip to a Veron Luscombe Sedan of 24" span to the left wing to flatten out an over banked turn. It was about 3" long of 1/16" square, that gives an inconspicious means of trimming. It worked very well.

Cheers Ricky - I've now bought the smallest clear plastic protractor I could find to guesstimate thrusts a little more accurately... those struts and all really get in the way and the black tissue camouflages readings... must try harder!

Gurney strips are intriguing and I'd like to give one a go, but I'll stick with the bendable acetate version at least until I've re-tuned these other issues.

 Smiley Jon
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Jack Plane
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« Reply #51 on: March 26, 2017, 12:14:19 PM »

Keyhole nose surgery complete, now with thin ply bulkhead in place of old thick balsa one, allowing proper screws to be used to achieve 2.5deg each of down-thrust and side-thrust (see pre-Joe Bugner nose photo below), went over to Berinsfield this morning for Round 2 of indoor trimming.

Trimming procedure seemed to be:

1.  Get the motor power just right; not easy to accurately adjust such a small and slipperly CO2 cylinder and locking-ring to find that incredibly narrow sweet-spot between too much thrust/rotation of the fuselage and too little power to climb.
2.  Set the rudder just right; again very sensitive to find the best position, avoiding either no turn or too much!
3.  Steam in a good dose of wash-in by putting the whole inner wing tip into my mouth, breathing and twisting; this method having replaced the acetate trim tab.

By trial and error got some of the way there - better climb with the more moderate down-thrust than before - but still found the initial turn too tight before opening out too quickly, this being the typical result:  https://goo.gl/photos/7nVGejpavefSDequ9

Nice bang at the end huh?!  Shocked  Becoming too much of a habit really!  Sad

After which I decided to increase the right thrust a tad, but, because I also started to experiment with a 0.5g bit of tip-weight on the inside wing at the same time (like mixing grain and grape... not a good idea!), the Piet acquired a very drunken flight path, then quickly stalled and smacked its nose hard down onto the ground... so we went home with a very floppy firewall!

Jon
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Re: Peck Peanut Pietenpol G-24 powered
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danmellor
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« Reply #52 on: March 26, 2017, 12:54:32 PM »

my usual trick is to use small "washers" cut from silicone fuel tubing between motor and firewall. Thrust angles can be adjusted in very precise amounts with a partial turn of the mounting bolts. Works best with a 3 point mounting and I'm not sure if the G24 has that...!

Cheers,

Dan.
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Jack Plane
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« Reply #53 on: March 26, 2017, 01:14:30 PM »

Cheers Dan

Yes, it seems mostly to do with side-thrust; fiddling with wing-tabs or tip-weights can only be secondary tweaks.

Ian Melville, who kindly filmed that flight, suggested the same 'washer' technique.  The G-24 is a three point fixing, so the method should work.

Jon
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Jack Plane
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« Reply #54 on: March 27, 2017, 04:10:02 PM »

Technique worked a treat!  Cheesy

Now, with 5 deg right-thrust and 2.5 deg down, the Piet flew beautiful circles outdoors in the relatively calm late afternoon air today.

Then I tried to film the second flight, but clonked the launch and did a wee bit of damage to the nose... so please take my word for it!   Grin
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