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Author Topic: Peck Peanut Pietenpol G-24 powered  (Read 3542 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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DHnut
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« Reply #55 on: April 04, 2017, 02:22:44 PM »

Jack,
       Well done! The Aircamper is not an easy model to trim especially as the rudder is so sensitive and the short nose clearly requires more side thrust. I must try the squashy washer trick as it must be better than fiddling with washers. I agree about the throttle adjustment in cowled situations, it is a plain. Loo forward to seeing a video of the action.
Ricky     
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FFmodeller
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« Reply #56 on: April 04, 2017, 03:05:40 PM »

Good to hear of your success ... not sure if I believe you though ...  Wink Smiley
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Jack Plane
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« Reply #57 on: April 05, 2017, 03:26:27 AM »

Ricky
Weather here due to be really calm by end of week, so an outdoor session beckons! The Kid's on hols now, so that'll be a two-inner-children event, and one where I don't have to be incompetent cameraman as well as launch-wallah!  Then there's Newbury on Saturday... for a bit of balsa-on-brick action!  I think I've sussed the 'throttle' setting (we're talking single degree tweaks here!) but with CO2 what works one day seems to be too much or too little the next.

Russ
It true!!  I swear it!
It was a funny old day.  Some instinct said to pop the Piet and the charger in the car.  I had to go to my woman's place to hang a couple more doors, but decided to swing past Swindon Model Centre first  to buy a few bits and bobs before they close down forever.  The car had a bit of a rumble, which got worse as I drove out the Grungeopolis.  Driving very gingerly, to the considerable annoyance of some Audi-head behind me, I sniffed out a repair garage on some random industrial estate to have a look:  it was the front offside brake system which had gone metal-on-metal.  I couldn't continue on as the risk was there could be total hydraulic failure.  The Green flag van man came quickly, but said he couldn't tow as my CRV is permanent four-wheel drive (which explains the slightly pants mileage!).   It was then a long wait for the piggy-back option.  Taking the dog for a walk, I discovered a small park behind some 1970s houses, the sort of patch the developer couldn't exploit as it dropped to a stream where ground became muddy, but enough for a casual, wonky-posts football pitch.  By the time the dog had played enough "catch/fetch/find-it/bring!" with an old tennis ball, and had a steamer (yes I bagged it AND put it in a bin rather than hang it on a tree for some deer to die ingesting plastic covered dog-waste), I'd got a feel for the way the breeze was blowing around the patch.  So back to the car with the dog, and back again with the Piet...

And - joy-upon-joy! - from one corner to the far one, the Piet circled and flew and circled and flew and didn't stall or rotate in or do anything else except make me feel like an eleven-year old all over again!  Cheesy
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Jack Plane
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« Reply #58 on: April 08, 2017, 06:26:27 AM »

Two or three fine flights in the calm sunshine late yesterday afternoon  Smiley

Fifteen seconds from hand-launch seems about average.
Steamed in a fair amount more of up-elevator,
but height gained outdoors depended really on whether I launched
into a bit of lift... or a little bit of downdraught!

Here the best of the videoed flights:
https://goo.gl/photos/U8KHGBGqjvsb3NSX7

And an animation from stills of the best flight:
https://goo.gl/photos/7Aq87oFrcnWgqkWHA

I'll call it a day for now, and return the Piet to its ceiling hook display.
I've learnt hugely from making and trimming this model,
and thanks, as ever, for all the input from forumites!  Grin

Cheers
Jon
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danmellor
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« Reply #59 on: April 08, 2017, 07:39:02 AM »

Very nice! Glad you got it sorted in the end.

Cheers,

Dan.
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Jack Plane
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« Reply #60 on: April 08, 2017, 08:16:05 AM »

Thanks Dan!
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Fudo Myoo
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« Reply #61 on: April 08, 2017, 03:52:40 PM »

Nice to see you got it sorted in the end Smiley
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FFmodeller
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Russ Lister



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« Reply #62 on: April 08, 2017, 04:59:00 PM »

Looking great now Jon  Smiley .... looks like it might even have a little power in hand? (thinking when you fly indoors more in that respect)

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DHnut
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« Reply #63 on: April 08, 2017, 10:31:48 PM »

Jon,
      A great flight and I think Russ is right that you have power in hand. A slight reduction would also give a longer motor run and would open out the turn under power. Your comment on being nose heavy is also spot on as well. I found with the Comper I had to add tail weight to get a reasonable glide. This is a model well worth perservering with. Weel done
Ricky   
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