Go Back  RCU Forums > RC Airplanes > Kit Building
Reload this Page >

trying to identify a 15-20 year old Decathlon (kit built)

Notices
Kit Building If you're building a kit and have questions or want to discuss kit building post it here.

trying to identify a 15-20 year old Decathlon (kit built)

Old 10-25-2016, 10:45 AM
  #1  
foodstick
Thread Starter
 
foodstick's Avatar
 
Join Date: Mar 2005
Location: ankeny, IA
Posts: 5,597
Likes: 0
Received 13 Likes on 11 Posts
Default trying to identify a 15-20 year old Decathlon (kit built)

I was given this plane by a friend, His father built it 15 -20 years ago.. here are the specs..

64 inch wing span
45 inch length
11 inch root rib

This plane had been hanging for years and fell to the concrete garage floor. So after converting to electric I also had to rebuild and paint the cowl,wheel pants , and scratch build wing struts. there were other repairs along the way , and I changed some of the servo installations to what I am used to. I have the cowl split..with paint drying right now.It is setup so that the bottom cowl clicks on with alignment pins and magnets..and allows access to battery changes.

If anyone knows the proper CG I would love that info as well !
Also using a 6 cell 3650 Lipo I am looking at an all up weight of 6 3/4 pounds. Without a fully put together balance I am pretty sure its close and a bit nose heavy as is.

I know typically the balance should be in the 28% of chord..so I will go with that if nobody knows the actual kit numbers.

Old 10-25-2016, 12:03 PM
  #2  
tailskid
My Feedback: (34)
 
tailskid's Avatar
 
Join Date: Nov 2001
Location: Tolleson, AZ
Posts: 9,552
Received 7 Likes on 7 Posts
Default

Don't know the mfg but I would guess the CG should be right on the main spar (or 25% of wing chord).
Old 10-25-2016, 01:11 PM
  #3  
scale only 4 me
My Feedback: (158)
 
scale only 4 me's Avatar
 
Join Date: Jan 2002
Location: Avon Lake, OH
Posts: 10,378
Received 51 Likes on 49 Posts
Default

most likely the Great Planes http://www.greatplanes.com/discontinued/gpma0185.html

http://manuals.hobbico.com/gpm/gpma0185-manual.pdf

I had one, good flier

BALANCE YOUR MODELNOTE: This section is VERY important and mustnot be omitted! A model that is not properly balancedwill be unstable and possibly unflyable.

D 1. Accurately mark the balance point on the bottom ofthe wing on both sides of the fuselage. The balance point isshown on the plan (CG), and is located approximately 3-1/4inches back from the leading edge. This is the balance pointat which your model should balance for your first flights.Later, you may wish to shift the balance up to 3/8" forwardor back to change the flying characteristics. Moving thebalance forward results in a model that is more resistant tostalls and spins but also may act sluggish and require morespeed for takeoff and landing. Moving the balance aft makesthe model more agile with a lighter and snappier "feel" andoften improves snap roll and knife-edge capabilities. In anycase, do not balance your model outside the recommendedrange.

D 2. With the wing attached to the fuselage, all parts ofthe model installed (ready to fly), and an empty fuel tank,block up the tail as necessary to level the stab.
Old 10-25-2016, 02:04 PM
  #4  
foodstick
Thread Starter
 
foodstick's Avatar
 
Join Date: Mar 2005
Location: ankeny, IA
Posts: 5,597
Likes: 0
Received 13 Likes on 11 Posts
Default

Awesome, thanks guys.. I will go put those marks on the wing right now ..
Help appreciated.
Old 10-25-2016, 02:19 PM
  #5  
RICKSTUBBZ
 
RICKSTUBBZ's Avatar
 
Join Date: Oct 2007
Location: Hempstead, TX
Posts: 1,500
Received 22 Likes on 19 Posts
Default

It looks like a Great Planes Super decathlon to me as well.
Look up the manual with the link SO4M posted above and set control throws up using that as well.
To much elevator travel can kill this plane.

Lots of bad press for this plane back in the day. People expected it to fly like a cub. It is not a Cub. The one I built flew/flies very nice. Knife edges like nobodies business.

Here is a couple pictures of one I built for my son along with a very short video.
Finished weight 6lbs 12 oz.



https://www.youtube.com/watch?v=qjm2mYY_fQc
Attached Thumbnails Click image for larger version

Name:	GP_Decathlon-17.jpg
Views:	123
Size:	370.9 KB
ID:	2187525   Click image for larger version

Name:	GP_Decathlon-19.jpg
Views:	119
Size:	371.0 KB
ID:	2187526  
Old 10-25-2016, 03:13 PM
  #6  
foodstick
Thread Starter
 
foodstick's Avatar
 
Join Date: Mar 2005
Location: ankeny, IA
Posts: 5,597
Likes: 0
Received 13 Likes on 11 Posts
Default

Went and checked it.. Much more nose heavy than expected. I will need to move the batter back a few inches further ...

When I was looking at the list of out of production planes it shocked me to see so many ! I had no idea that many planes have been discontinued... I guess the lack of building and the glory years of cheap labor building ARFs did in a lot of products.
Old 10-25-2016, 07:17 PM
  #7  
foodstick
Thread Starter
 
foodstick's Avatar
 
Join Date: Mar 2005
Location: ankeny, IA
Posts: 5,597
Likes: 0
Received 13 Likes on 11 Posts
Default

Started the new battery mount, had to build a tray to move the battery back just about 3 inches all right.... Just for fun I sat some lead on the tail.. if I had left the battery up front it would have needed nearly 5! oz lead. The battery is now back in the cockpit instead of up where the fuel tank normally goes...

It will be worth the added work though.
Old 10-29-2016, 05:46 PM
  #8  
DGrant
My Feedback: (4)
 
DGrant's Avatar
 
Join Date: Dec 2001
Location: Clovis, CA
Posts: 2,194
Received 30 Likes on 27 Posts
Default

These are very fun planes. As mentioned they're far from any high-wing trainer/cub style plane. With that symmetrical wing they're very aerobatic, and will do many things even modern aerobats won't. They snap roll on command, knife edge is very easy, although there will be more coupling involved and knife edge will take some serious rudder/aileron manipulation, once you figure out how much of what to command it, you'll see what it will really do. The rudder is very effective as well...very powerful.

This plane has come up several times over the years, and every time I see one, I want to get mine out and give it a once over and go fly. Its one of the classics from the late 80's and 90's that unfortunately was discontinued.. yes probably due the ARF revolution. I got mine over 20yrs ago, and worked on it off and on for a few years, before I finally finished it. I have a .61 two-stroke in it, and it flew very well. That GreatPlanes discontinued list is quite amazing too, there were so many nice kits that they quit making... I've collected many of my favorites over the years though... thinking I'll build them some day... I'm now starting to think I should get busy with them.. I'm pretty sure I have enough of those kits to last me 10yrs if I never bought another plane.

Enjoy.. your in for a treat!
Old 10-29-2016, 06:30 PM
  #9  
foodstick
Thread Starter
 
foodstick's Avatar
 
Join Date: Mar 2005
Location: ankeny, IA
Posts: 5,597
Likes: 0
Received 13 Likes on 11 Posts
Default

It has two flights on it now re-maidened on a windy day and she flew pretty well.. two nice landings (whew)!

It does land a bit faster than I expected with a pretty strong wind but it was manageable.. I did a snap roll and she did tumble nice. I saw the comment above after the test flight about the elevator being a plane killer.. oh man, I have like 1.5 inch throw up and down... I don't tend to slam the sticks around unless I am attempting a stall maneuver so I got away with it I guess.I am pretty sure I am right at 6 3/4 pounds. I ended up with the battery right in the cockpit to balance. I don't think any of it is in front of the dash. Getting the balance right was a shock, as I have never had a converted glow go this way.

Now I am going to go watch the video above as I somehow missed it before
Old 10-30-2016, 03:38 PM
  #10  
foodstick
Thread Starter
 
foodstick's Avatar
 
Join Date: Mar 2005
Location: ankeny, IA
Posts: 5,597
Likes: 0
Received 13 Likes on 11 Posts
Default

This thread is not going to be one of those that drags on with endless pics and videos... In short the plane flew great and I was pushing my luck with snap rolls and spins......

My buddy never made it to the field today, and it was the final day for this plane.
At the end of two picture perfect flights .....

I did a pretty fast snap roll. It went around three times. And then I let it fall into a nice spin... I watched it for awhile and then tried to let it stabilize and fly out.. it didn't..
So I pushed nose down, and tried to ease out.. I had done it multiple times before... and I was easy on the sticks...then it went from a left spin to a right spin, tried to stabilize it again..
Went from right spin to left spin.. then it went behind the levy.. into what was a cornfield a few weeks ago...

Fuse was really messed up and torn in half, cabin window area destroyed, and the wing was hurt internally hard points and ribs busted....broke wheel pants, wing struts, etc.


I should have just babied it around instead of stunting it until my friend got to fly it ...

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.