kctrading

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Questions....???

I just purchased this 1/4 scale Piper Cub from a friend at work.

How's it going to fly with the installed OS FP .91 Surpass 4-stroke engine? From all what I have read this is on the bigger side if not to big?

Also is a 13"x6 airscrew prop. Is this correct for this engine and plane?

Also what fuel should I run...I have a fresh bottle of 15% airplane fuel....I've read somewhere 30% Heli fuel?

Plane has the same weight and dementions as the Great Planes Piper J-3 Cub 40 Kit .40-.61,76.5" but looks to be a much older build?

It's got some other concerns like the loose elevator joining rod, cracked frame on rudder balsa, missing wing struts, but I am going to ask that on the fix section.

Also anyone have video urls as I would love to see how this plane flys!!!

Thanks for any help and suggestions!

Ken
Hemet, CA

GalenB

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This is not a 1/4 scale Cub as a 1/4 scale Cub has a 104" wingspan... Your Cub is a 20ish% scale Cub if it has a 76" wingspan. A Cub of this size should fly well on a .50 four stroke using a 12X5 prop -- IMHO the engine you have is much too big...

kctrading

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Hey GalenB,

While you were posting I was reading up on the Great Planes manual since the dementions are the same....can I use this manual to help get this plane going? [link=http://www.greatplanes.com/manuals/gpma0160-manual-v3.pdf]manual pdf[/link]

They recommend the following on the engine

The recommended engine size range is as follows:
.40 - .61 cubic inch displacement 2-cycle
.48 - .80 cubic inch displacement 4-cycle They say the .70 Surpass would be great for For maximum aerobatics! Gee...how much over kill is a .91 compared to a .70?

You are right on the scale size....they say 1/5.5 or 18%....

Thank you for purchasing the Great Planes Piper J-3 Cub!
This J-3 Cub kit is a 1/5.5 (18%) scale model of a full-size J-3
Cub and retains the real plane’s great flying characteristics.

My friend at work "Glen" has a lot of exp with big gas planes....being that I like fast things I may end up likeing it If not I guess I would have to sell it and get a smaller engine and recheck CG...hmmm

Ken

GalenB

My Feedback: (18)

If the CG checks out I would leave the .91 in since it's already mounted... Cubs are known for being tail heavy so a larger engine is one way to make up the diff... I flew my H9 80" (20%) Cub on an old tired Magnum .52FS swinging a 12X5 prop. I flew great and was very scale... With the .91 you'll want to ease the power in to about half for take off as a Cub can be a hand full on take off -- you must use rudder... Also -- check the main gear and ensure that the wheels have a degree or two of toe in -- meaning the fronts of the wheel are tilted toward one another...

kctrading

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Good info...I notice that the .91 weighs about 2oz more than the .70...I notice that there is a 1.5oz weight on the very end of the fuseloge....I'm going to check everyting over like I was building it again fresh, never know how the other guy built it or built it correctly...thanks!

Ken

Bass1

Ken, You may be under propping the engine. The manual states the folowing: Stunt planes use 11x11,11x12,12x10 12x12,13x9 Scale models 13.5x8,14x7, 15x6, 16x6, 12x8(three blade). I've been running a 14x6 APC on an Extra 300 and it's a good match also. I think the previous owner picked a 13 for ground clearance and the smaller pitch for slower airspeed. I've been using 15% Coolpower Heli in this engine for 5 years and it still runs like new. You should be able to fly scale like at less than half throttle.

kctrading

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With this engine how much thrust are we talking about at lower speeds? What would it take to hover a 7.5lb plane? What would be the max rpms with the 13x6 or maybe a 13x9 prop? I've got about 3" of ground clearance with the 13x6" prop.

Also are there any good freeware prop programs on the web?

Thanks!

Ken

Texastbird

Looks like a Goldberg Cub to me. Has it ever flown with this engine?

kctrading

My Feedback: (2)

Fellow I purchased this from said his grandfather flew it all the time with this engine....what is the difference between the Surpass II and the orginal Surpass engine? I'm thinking this is the older one.

Ken

kctrading

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Update:

Last month larger plane was purchased with counterfeit $100 bills locally in Hemet California

I had this plane along with some RC radios and wheels and tires off a 2005 v6 mustang for sale www.recycler.com and fellow calling himself Steve from Riverside CA driving a white 2002+ Ford Explorer came over and purchased all of the items for $700...paid with seven new $100 bills, they all looked real to me!....went to the bank the next day with my paycheck and deposited them...teller supervisor said they did not feel quite right...they passed the ink and ultraviolet light test...even had the correct watermarks, paper strip and color....they called the Secret Service the following morning and ran the numbers (each had different numbers) and they came back as counterfeit bills! I did file a local police report to no avail...if you guys see someone selling this plane please let me know as they may wait a while for things to cool off?

I found out later from the Secret Service that these were most likely the "North Korean Super $100 Bills" Only thing that will give them away is they feel slightly rougher than the orginal.

Ken
Hemet, CA