phoenix decathlon
10-08-2007, 04:38 PM
#202
Senior Member
RE: phoenix decathlon
ORIGINAL: Ugo Ferrari
Has anyone had an engine cooling problem with the Decathlon? I think I may have ! What did you do to cure the problem ?? I'm using a GMS .47 and I think it's running hot....[:-]
Thanks for any inputs !
Ugo
Has anyone had an engine cooling problem with the Decathlon? I think I may have ! What did you do to cure the problem ?? I'm using a GMS .47 and I think it's running hot....[:-]
Thanks for any inputs !
Ugo
I flew mine with a OS46AX to begin with. Retrofitted an OS55AX to see how it'd do pulling that 6lb 5oz bird around. Neither engine ever broke a sweat.
If the off-side intake is left open, the cool air that comes in will go straight to the hot air exhaust openings and actually crowd out some of the hot air trying to get out. Cool air is easier to move than hot air. And cool follows cool. And hot air gets left where it got hot. And it just gets hotter and less easy to move. etc etc
But either block the unnecessary cool that's going to screw up the works, or divert it toward whatever needs to be cooled and the cooling system works better.
See the baffle in the useless side? It's a piece of polystyrene insulation that weighs zip. It is also very easy to sand and fit. I think it took me 5 minutes to fit it and epoxy in.
10-08-2007, 04:41 PM
#203
Senior Member
RE: phoenix decathlon
OOps........ Sorry to show a picture with the fuel pipes hanging out. How untidy. 
The two hoses are out for filling. I push 'em back in and the plugs make them fat enough to stick in the holes and stay against the cowl.
The two hoses are out for filling. I push 'em back in and the plugs make them fat enough to stick in the holes and stay against the cowl.
10-08-2007, 05:16 PM
#204
RE: phoenix decathlon
Thanks Rock, That sounds like an easy fix. I'll give it a shot and try it next weekend ! I already opened up the under side a little but haven't tried that yet. I didn't want to butcher it up any more. Between that and your fix , my cooling problem should be fixed... Thanks !
By the way, My "Pipes" are hanging out too ! On the other side. LOL !
Ugo
By the way, My "Pipes" are hanging out too ! On the other side. LOL !
Ugo
10-08-2007, 10:22 PM
#206
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RE: phoenix decathlon
ORIGINAL: da Rock
If you're starting from scratch (to modify that ARF) there is something that would work great to hold the wings together.
Glue strong root rib doublers to each wing half. Have tabs stick down beneath. Bolt the two together to hold them together in flight. There won't be very much force trying to separate them anyway. And the wing hold down bolts are going to do that anyway AND the two hold-down stubs in the wing LE do that also. So why do it?
If you glue in a cross piece in the cabin opening that had a slot for the two new wing tabs, the slot would provide just a bit extra insurance for holding the two halves tightly together AND the cross piece would provide bracing for the wing on inside loops. Wings that are glued together gain measurable spanwise stiffness from being one piece through the center of the span.
But truth is, that wing joiner aluminum tube is quite robust and fits snugly. My ARF had only that one tube, btw.
If you're starting from scratch (to modify that ARF) there is something that would work great to hold the wings together.
Glue strong root rib doublers to each wing half. Have tabs stick down beneath. Bolt the two together to hold them together in flight. There won't be very much force trying to separate them anyway. And the wing hold down bolts are going to do that anyway AND the two hold-down stubs in the wing LE do that also. So why do it?
If you glue in a cross piece in the cabin opening that had a slot for the two new wing tabs, the slot would provide just a bit extra insurance for holding the two halves tightly together AND the cross piece would provide bracing for the wing on inside loops. Wings that are glued together gain measurable spanwise stiffness from being one piece through the center of the span.
But truth is, that wing joiner aluminum tube is quite robust and fits snugly. My ARF had only that one tube, btw.
10-09-2007, 04:04 AM
#207
Senior Member
RE: phoenix decathlon
ORIGINAL: Fastsky
To be honest, I didn't change anything on mine and haven't noticed an overheating problem?!?[8D]
To be honest, I didn't change anything on mine and haven't noticed an overheating problem?!?[8D]
10-09-2007, 08:31 AM
#209
Senior Member
RE: phoenix decathlon
Think I'll pass on moving up there. Used to live in Minnesnowta for a number of years. Although I never had an overheating problem in Minnesnowta, I happily moved back down here where it's lots warmer year round. But never wanted to live in Florida where Ugo is flying his overheating Decathlon. Too hot for me. And sounds like for his airplane too.
11-01-2007, 05:37 PM
#210
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RE: phoenix decathlon
Hi, I dumb thumbed my Decathlon all the way to the ground today. Its ugly but repairable. Does anyone know were could I get the all the windows for this plane?? I need to rebuild the fron half of the frame and TH doesn't have the windows.
Thanks in advance for the help!!!
Thanks in advance for the help!!!
02-04-2008, 09:35 AM
#211
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RE: phoenix decathlon
I have an old Fox 50 in mine, and have some minor cooling issues with it. Going to try blocking off one of the intakes this spring though and see how it goes 
Mine's a sweetheart in the air, and my new favorite plane to do touch and go's Mine at least either doesn't have any bad ground characteristics, or I'm just that darn good (joking of course)
Going to do some more detailing and customizing this winter on it. Now I just gotta figure out how to cut the letters with the right degree of slew to match the windows [8D] .
Mine's a sweetheart in the air, and my new favorite plane to do touch and go's
Mine at least either doesn't have any bad ground characteristics, or I'm just that darn good (joking of course) Going to do some more detailing and customizing this winter on it. Now I just gotta figure out how to cut the letters with the right degree of slew to match the windows [8D] .
04-08-2008, 08:35 PM
#212
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RE: phoenix decathlon
I know this is ressurecting an old thread but I have a Decathlon question.The Decathlon in question is the one that started this thread a year or so ago. My son got this plane for Christmas of '06. He grew weary of flying it about 8-9 months ago. I got tired of watching it sit idle so I have put an engine and radio gear in it. I remaidened the thing yesterday and boy what a pig in the air. It flys like you got the brakes on. I have went over every thing I know to to check. All I have found out of kilter is the wing has about 1 degree of negative incidence (???) front of wing down about 1 to1 1/4 degrees. I know off is off but would that make that much difference? I had to trim in several clicks of up elevator to get it to fly level. It's flying like it has a .25 on it instead of the TT Pro 46. Got an APC 11/6 prop on it. Any suggestions ???
04-09-2008, 10:43 PM
#214
RE: phoenix decathlon
I'm not sure how I can answer your question, ABELL. However, I'm thinking it could be with the engine's mixture or fuel used. I had a similar problem with a Nexstar I once had. It was hard to get off the grass strip, and it flew like a pig. It flew much better after I adjusted for a higher RPM without leaning the engine out too much. If your Citabria is the same way now as it was when your son flew it, then I'm thinking the engine. Otherwise, you could play with the wing incidence and probably set your CG back slightly, and see how that works. I currently have a Lanier Citabria in the works, but haven't quite figured if I want to use the standard engine mounts. I'll know more about these planes after I get the chance to fly it a few times.
NorfolkSouthern
NorfolkSouthern
04-10-2008, 01:54 AM
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RE: phoenix decathlon
Hi Abell!
I have the Seagull Decathlon and experienced a similar problem during my first flights. The speed would simply not get up.
I noticed you're using a 11x6 propeller. I recommend a bigger prop on this aricraft because of the wide body configuration compared to a relative small engine. Try 12x6. I think it will do some improvement.
When it comes to the wing incidence you could try getting the negative into positive. Although it is a fair chance of getting the same speed or even slow the airplane even more..... It don't mather on the speed if it's positive or negative 1 degrees of incidence. But the positive will increase the lift of course.
I used an ASP 61 fourstroke with 13x6 at the start. Changed quickly to 14x6, and tried 14x8 later. 14x8 was the best, but the power was a little bit low. So changed my ASP 61 fourstroke for a ASP 80 fourstroke. Still trying to get time to mount it in.....
I have the Seagull Decathlon and experienced a similar problem during my first flights. The speed would simply not get up.
I noticed you're using a 11x6 propeller. I recommend a bigger prop on this aricraft because of the wide body configuration compared to a relative small engine. Try 12x6. I think it will do some improvement.
When it comes to the wing incidence you could try getting the negative into positive. Although it is a fair chance of getting the same speed or even slow the airplane even more..... It don't mather on the speed if it's positive or negative 1 degrees of incidence. But the positive will increase the lift of course.
I used an ASP 61 fourstroke with 13x6 at the start. Changed quickly to 14x6, and tried 14x8 later. 14x8 was the best, but the power was a little bit low. So changed my ASP 61 fourstroke for a ASP 80 fourstroke. Still trying to get time to mount it in.....
04-10-2008, 04:36 AM
#216
Senior Member
RE: phoenix decathlon
Mine was extremely fast with an OS46AX, and it's a bit faster now with an OS55AX. The airframe isn't your problem. The engine forums would return more and faster help on your problem. A wing that's off 1.5 degree plus a couple of clicks of elevator trim wouldn't do much at all to the speed. It certainly would not do what you describe. Engine/fuel feed/fuel tank all are probably much more suspect.
04-10-2008, 03:59 PM
#217
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RE: phoenix decathlon
Thanks guys !!!!!!!! It seems like when the son was flying it we settled in on a 12/5 prop and that was after much trial and error. I went with the 11/6 because that was all I had on hand at the time. This is one of those planes that you put back in the air with spare parts and left overs. When Ben was flying it we had a TT pro 46 on it but mind you it was a differert engine. I like to run all of my engines on the rich side and by rich I mean 700-800 off of lean. I can safley get 5 or 6 hundred more rpm out of it without risking a lean run. I'll play around with props and tuining issues and see what I can do with it ......... Again thanks guys
