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Author Topic: Peck Cub trimming issues  (Read 1168 times)
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cglynn
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« on: July 30, 2014, 10:10:08 AM »

Greetings all.  I built a Peck Cub peanut a while back and was pleased with the way model came out.  Then I tried to fly it.  All is not well on the flying front.  First, the model was showing a major stall.  I checked the CG and it was way aft.  So I added around 3g of weight to get it balanced (this is with motor installed).  It now sort of flies, but doesn't really turn, and doesn't really want to climb with 900 turns.  Motor is a 13" loop of 3/32 TanSS.  Prop is a Clem style made of 1/32 balsa, set to a 1.4P/D ratio.  All up weight with motor is 16g

So I am looking for some suggestions on how to proceed.  I am thinking I should add some rudder to get it to turn, and maybe some right thrust (want to trim for right turn) and crank in more turns?  Longer motor?  Shorter motor?  Thicker Motor?  Thinner Motor?  Combination there of?  This one has me baffled.

Thanks
Chris
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ironmike
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« Reply #1 on: July 30, 2014, 12:44:08 PM »

Hi Chris

I assume this is the clipped wing version?
If so these baby's love to fly in RH pattern.
I would put in a little R thrust and remove some
nose weight. Also a touch of W/ in on the R panel
with a little W/ out on the left. Depending how it turns
add R rudder as needed. These wing warps must be very subtle.
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cglynn
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« Reply #2 on: July 30, 2014, 02:08:24 PM »

Mike

Yes, this is the clipped wing version.  I will try to play with the thrust line and see how that goes.  Do you think I am on the right track with the motor I am using? 

Thanks
Chris
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ironmike
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« Reply #3 on: July 30, 2014, 02:17:33 PM »

Prop sounds OK but maybe go to 1/8 rubber same length
I had one of these in the late 70 when I flew with the CFFS
in Ohio. It flew like gang busters and was very competitive.

M
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Maxout
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« Reply #4 on: July 30, 2014, 03:16:41 PM »

Chris, you might want to dial back to a Peck 6" for trimming, then consider later whether there's performance to be gained by switching to a balsa prop. The plastic prop will make it easier to get things trimmed. You might find that after twisting the blades to a higher pitch, that the Peck gives you very good performance.

Also make sure the glide is good before trying power. You want a flat right hand glide, which you'll have to get using right rudder and perhaps some left roll trim to prevent a death spiral. (pretty much what Mike M said already).
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rick121x
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« Reply #5 on: July 30, 2014, 03:49:27 PM »

.
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cglynn
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« Reply #6 on: July 30, 2014, 10:41:53 PM »

Thanks for the tips everyone.  I have a place to start next time I fly. 

Mike, its funny you mention CFFS.  I am flying with CFFS for their monthly outdoor contests and NOFFA during the winter months.  Great group of guys. 

Thanks again.  I will post up how things went after my next flying session.  Will be a few days.

Chris
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cglynn
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« Reply #7 on: July 31, 2014, 10:37:08 PM »

Success!!!  I was able to get some bonus flying time today so off to the field with the Cub.  I swithched props to the 4 3/4" silver peck, adjusted the nose weight and the thrust line, wound in 300 turns and she maintened level flight and landed smoothly as the torque burned off.  Looked really good.  Then I cranked in 600 turns.  Just a touch of stall.  A tiny bit of clay fixed that and she flew really nice.  At 900 turns she climbed to about 15 feet, made a few circles and landed.  At 1100 turns she is showing stall again.  Not severe, but a bit.  Still it flies, and flies very well. 

As pleased as I was with the test session, there is room for improvement.  I took the model home and looked at the thrust line even more.  Turns out that when I built this plane, I goofed up and built UP and LEFT thrust into the fusealge (something about haste and not paying attention to detail).  So I hit the nose with a sanding block and dialed in a healthy amount of downthrust and neutral thrust.  It will probably turn left because of prop torque and what not, but I can deal with that.  I might shim the nose block and add some rudder for a right pattern.  Next test session I will see how she handles some 1/8 rubber.  Hopefully I can get her to handle the torque and climb.  Next contest is on Aug 10th, and I want to at least be able to make some officials with this plane.

Thanks for the all the advice and tips.  You guys got me flying a model that I was about to give up on and use for a mantel piece.
Chris
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mkirda
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« Reply #8 on: August 01, 2014, 08:37:50 AM »

Success!!!  I was able to get some bonus flying time today so off to the field with the Cub.  I swithched props to the 4 3/4" silver peck, adjusted the nose weight and the thrust line, wound in 300 turns and she maintened level flight and landed smoothly as the torque burned off.  Looked really good.  Then I cranked in 600 turns.  Just a touch of stall.  A tiny bit of clay fixed that and she flew really nice.  At 900 turns she climbed to about 15 feet, made a few circles and landed.  At 1100 turns she is showing stall again.  Not severe, but a bit.  Still it flies, and flies very well. 

As pleased as I was with the test session, there is room for improvement.  I took the model home and looked at the thrust line even more.  Turns out that when I built this plane, I goofed up and built UP and LEFT thrust into the fusealge (something about haste and not paying attention to detail).  So I hit the nose with a sanding block and dialed in a healthy amount of downthrust and neutral thrust.  It will probably turn left because of prop torque and what not, but I can deal with that.  I might shim the nose block and add some rudder for a right pattern.  Next test session I will see how she handles some 1/8 rubber.  Hopefully I can get her to handle the torque and climb.  Next contest is on Aug 10th, and I want to at least be able to make some officials with this plane.

Thanks for the all the advice and tips.  You guys got me flying a model that I was about to give up on and use for a mantel piece.
Chris

John Regalbuto makes an adjustable thrust bearing that might work for you, Chris.
JOHN REGALBUTO <regal33@verizon.net>

This is what he sent out to me:
"The first batch of the Regal Improved Nose Button is ready.
The buttons feature a 7075 aluminum alloy front flange to replace the former nylon flange.  the aluminum flange provides superior clamping of the the ball.  I think a crash may now result in a damaged propeller rather than a change in the thrust setting.   See the attached photo.
 
Ready to supply nose buttons in the following sizes
        Large 047 prop shaft diameter, rear adjustable
        Large 047 prop shaft diameter, front adjustable
        Medium 032 prop shaft diameter, front adjustable
        PNUT 032 prop shaft diameter, front adjustable
 
Pricing is $7 for the Medium and Large.    The peanut price is $8 since the 00-90 screws are so expensive.  Shipping is $2.50 for any amount of buttons ordered.   As before, a reverse S hook propshaft and hex key are included."

I ordered a couple of the Medium sized ones for scale models I plan to have ready for the EAA contest in 2015.

Regards.
Mike Kirda
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cglynn
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« Reply #9 on: August 01, 2014, 04:20:50 PM »

Mike, I will have to check those out.  I bet they make trimming an easy task.  I've got the cub trimmed really well and am going to play with motors until I find the sweet spot.  She seems to like lots of power so I am going to shorten my 1/8" loop to around 12.5" from 14".  We will see how it goes.

One another note, while trimming the cub I brought my Prairie bird along for testing.  Long story short, it found its way to the top of a very large maple and most likely will not be seen again, and certainly not in one piece if it ever does come down.  So I get to build and trim another one before Aug 10th. Fortunately it is an easy build, and I know how and where to save some weight on this one.

Chris
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mkirda
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« Reply #10 on: August 01, 2014, 11:04:57 PM »

My 50' carbon pole has come in handy getting my Lanzo Stick down from several trees...
The number of models I have recovered with that thing... Worth every penny.
http://www.allfishingbuy.com/Fishing-Pole/Pole-A1-JDS-130-15013.htm

Regards.
Mike Kirda
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Flyguy
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« Reply #11 on: August 02, 2014, 01:17:59 PM »

Don't want to hijack the thread, but thanks for that link Mike. My extending pole is 31 ft. but it seems that the plane is almost always up at least 40 ft., so I think I'm going to spring for the larger pole you mention. I'm assuming that, since it's carbon, it should be controllable by one person when fully extended, right? Larry
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mkirda
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« Reply #12 on: August 02, 2014, 02:00:55 PM »

Don't want to hijack the thread, but thanks for that link Mike. My extending pole is 31 ft. but it seems that the plane is almost always up at least 40 ft., so I think I'm going to spring for the larger pole you mention. I'm assuming that, since it's carbon, it should be controllable by one person when fully extended, right? Larry

Yes, it is.

I bought it specifically for retrieving indoor models from the top of Eagle Hanger at the EAA.
Up to 40' you can steer indoor if you are careful. It gets whippy any longer than that.

I think I did 6 flights on my Lanzo and it ended up in a tree three times. Twice at the top of fairly large ones.
I was very glad I brought the pole...

Regards.
Mike Kirda
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cglynn
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« Reply #13 on: August 04, 2014, 12:26:54 AM »

I will look into a pole.  I need one for indoor anyway.  Regardless, there was no way I was getting this model down.  Couldn't even see it from the ground.  As luck would have it, a really nice thunderstorm popped up the day after I lost the model.  My dad went to the spot where the plane was lost and sure enough, about 30 ft from the tree was the remains of the prairie bird.  Actually, the model was nearly intact.  The wing spar was broken in about four places, the tail feathers were hanging on by a thread, and the fuse was all torn up.  But the prop was salvaged, which is the good thing, as that is the only 6" peck prop I have.  A replacement is being built to about half the weight of the first one.  As of now, both fuse halves weigh in at 1.3g ( for the pair).  This was with 8-10lb wood and CA glue.  I have some lighter stuff for the tail feathers and wing ribs.  I am shooting for 10g less rubber.

Chris
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