Decathlon, To Super Or Not To Super, That is the question

Bartman

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#1
Hi all,

Well, I've been trying to keep it under wraps until it's home so as to not jinx the whole thing but it's out that I'm bringing home another project airplane this week. It's a late 70's vintage Decathlon and, while it's technically an airplane, it's more accurate to describe it as a pile of parts formerly known as a Decathlon.

In taking ownership of the pile of said parts I'm posed with the dilemma of what to do with it. In the parts are all of the items needed except spars to remake a set of wings as they would have come from the factory in the 70's. In the parts are most of the items necessary to hang a 150hp IO-320 on the nose. But is that what I want to do?

It's interesting to note that the factory makes available all of the current Super Decathlon features for retrofit to original vintage airframes. My plan is to drop off the frame at the factory on Friday so it can be placed into the jigs and checked for straightness and structural integrity. While it's there they can make whatever upgrades I ask for but again, what's the right answer?

So I'm asking for your opinions, I've got a few ideas, but I want to hear what you guys have to say.

I'm leaning towards building it with the IO-320 but doing upgrades to the gear, the wings (current design metal spars with HP ailerons), and to the panel along with an updated/new interior when the time comes. The -320 can always be yanked in favor of more power later on when time/money allows.

What would you do? What do you think I should do? Thanks in advance!
 

aftCG

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#2
What a cool opportunity. I have to plead stupid since I've only flown flapless Citabrias, but Super equals 180hp and constant speed prop or is there more to it?

Also cool that you are close enough to the factory fuselage jig. How much do the charge for that?
IMG_20170618_100904-01.jpeg
This one was transient a couple years ago (I think). Loved the paint. Couldn't help but notice the really beefy struts.

I understand it has since had a mishap due to landing gear failure.
 
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Bartman

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#3
Close! You're a comedian! lol

I'm going out to Kansas tomorrow and renting a truck to bring everything home but before heading home to NJ (Close!! :LOL::ROFLMAO::LOL: ) I'm going to make a side trip to Wisconsin to drop off the frame at the factory. It'll stay there for a couple of months while I bring everything else back to NJ, probably Saturday. Not sure what it's going to cost but they have to grind off some stuff to get it into the jig. I'd like to know the frame has a clean bill of health from the factory before spending any time working on it.

I honestly have no idea what I'm getting myself into but I couldn't resist! One goal, however unrealistic is to not get into for more than I can sell it for if I have to sell it. This can be my forever plane to enjoy into retirement so it's going to be done exactly how I want it but I just can't quite decide how that should be!

For example, the wood spar option......If I'm building the wings from scratch and using brand new Rainbow wood spars, is there really a problem? If I'm the original owner and I know the G meter won't exceed about 4 positive, is there anything wrong with building new wood spar wings other than all of those fugly inspection plates??? Probably not, right? It's a lot cheaper too.

So that's the kind of dilemma I'm facing. Avionics are rapidly changing and I'm not so sure there will be round instruments unless the cost to overhaul the ones I'm getting is much much cheaper than going digital.

And yes, a Super Decathlon has 180 hp and a constant speed prop. Decathlons at 150 hp can either be fixed pitch or constant speed. Even if I plan to compete in IAC events, is 150 hp enough for an aging part-time sportsman competitor?
 
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aftCG

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#5
I was going to keep my trap shut on spars. Ron's spars are the only way I would go. I've met him at his shop and he's quite a character.

I read somewhere he's out of spars. His pile was from a trip to Alaska and he told me how irked he was that the place that cut the logs didn't follow his instructions on grain direction, rendering quite a bit of it useless for spars.
Here's to hoping he makes another trip to Alaska to pick out a few trees.

Why would I go wood? Weight. Were I sitting on the opportunity that you are I would be obsessed with weight.

Covering system, prop, floor panels, landing gear, panel, interior, etc.
 

Bartman

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#6
Obsessed with weight is exactly where I'm at, funny you should say that. But removing weight or just saving it by not putting it in in the first place has to be legal so I've got a lot to learn about what I can do where. My IA is kind of shaking his head at me taking on this kind of a ground-up build but we'll just take it day by day.

In the name of weight I think it's going to be basic VFR for instruments and then comm, ADS-B, and a spot in the center for a removable mini tablet or an IAC sequence card and that's it. the tablet will be about one fifteenth what a TSO'd GPS moving map avionics component would cost from what little research I've done so far and if it's in the middle it can be the GPS/ADSB display while also keeping the spot available for the sequence card.

Are you saying the wood is heavier or lighter? I know it's definitely cheaper! Ron said he'll have another delivery of wood in about a month. :)

If anyone sees me getting fat on the options, scream at me!
 

Bruce

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#7
Really enjoy the conversations and I think we all share the enjoyment and decision making during the build process. I also learn from every ones post like the call on carbon fiber floors, as for which way to go I try to be more practical than perfect or cheeping out. By this I mean I am down to the fuselage and looking at the headliner it’s still in good condition not great and this is supposed to be a flyer not show. That being said I could put new fabric on and live with what is there less money less work. But!!!! For the cost of the headliner and my labor, why would I cheep out at this point or be that lazy??. Just to save a little. It would stink after completely recovering this to be unhappy with that decision.

All this to say super or not, what do you want the plane to do and how much will it cost to get there? More HP is always nice but for what gain constant speed prop for loss of weight,and increased maintenance cost my main driving factor would be cost over benefit.

One of my constant statements to folks is;

Don’t let your wanter beat your needer to death.

In the end be happy with your choice and best of luck
 

Bob Turner

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#8
I would try for a 160 HP field approval, maybe with factory help, since you are going to be making friends there. And maybe an MT composite C/S prop?

Have the factory change the fabric supports to accept aluminum gear. That way you can do the gear change at your leisure.

Put the larger instrument panel in. Trivial to do, and enables a "six pack". I went with venturi driven instruments, and a shutoff valve for inverted flight, but if you go glass they should work upside down. I designed my panel to accept standard 2 1/4" instruments on the bottom row, but made a special mount for the original automotive gauges.

Use Hooker style harnesses (I like "Silver Parachute") and skip the ratchets.

Spend some time smoothing the inside of the cowl. I am doing that now to aid in engine compartment clean up.

And add an alternator field switch. Put it on the checklist, or put it next to your avionics master.

Keep your 1977 gas tanks. Later production is not so great.

Stay with wood spars if your IA will let you do the annual spar AD. Ron will tell you they have no problems with Decathlon wood spars.

And retain the 1977 wing root fairings. That way you can change the windshield without removing the wings. Oh, and do what Ron says about mounting the upper skylight.

You will love this aircraft. It is not a short field aircraft, but mine has gone in and out of strips the Cub guys insist require 26" tires! Works fine. I have the 180, but see little advantage other than flat-out vertical stuff, which I do not do.
 

aftCG

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#9
Yes, the weight savings has to be legal but I learned in my adult years building flying models (including rubber powered scale free flight) to weigh EVERYTHING before it gets a green light. It's very educational if you live by the mantra "sweat the ounces and the pounds take care of themselves".
Where some people think this means titanium fasteners and cutting the handle off your toothbrush, the biggest weight savings are found in places most people don't look, or underestimate. By the way, titanium fasteners don't save much.
You can't do anything to lighten the steel tube fuselage. Wood spar wings are in the neighborhood of 60 pounds lighter.
ACA told me aluminum gear is like 11 pounds lighter. It's around $4k for a set. Finding them used is akin to locating Bigfoot.
ACA also sells carbon fiber floor boards. Much of my career is in composites and I'll just say I wish they offered them in fiberglass. Glass, carbon fiber, Kevlar etc are sold in ounces per square yard. Do you suppose 7 ounce carbon is lighter than 7 ounce glass? It's not, obviously. The floor boards in these planes would certainly be durable enough in either material if plywood has made it this far. Carbon parts are only lighter if you can take advantage of its strength and leave out everything not absolutely needed (and most products are not engineered to that level). By the way I think they said 4 pounds saved on the floor boards.

You will likely get into a tug of war with your IA over covering systems. They seem to want to use medium or heavy fabric and might suggest extra paint on top of the wings to fend off UV damage.

Oracover is probably the lightest option since it requires no paint.

High panel? No. And not because it's heavier but because it will tempt you with its vast emptiness. Vacuum system? Oh hell no.

Fixed seats. Ditch the speaker housing. Maybe do like the factory and ditch the switch panel, putting everything in front of you.

Maybe a wood prop.

I contacted MT to see if they had any options for 7 series Citabria and they said bluntly "no".

My beat up patched cowl is begging for me to take a splash and create a new one, actually vacuum bagged instead of the crude hand layup that sufficed back when fiberglass was new technology.

I love my skylight but it would have to buy it's way back in the plane during a covering job.
 
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Bob Turner

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#10
High panel - no good if your only mission is aerobatics or vertical work. I use my Dec to stay intrument current, and for limited cross country. The extra instruments are essential to my non-competitive aircraft. The Decathlon is as good at X-C as its Citabria counterparts. I think the 160 lyc would save you pounds and still provide decent performance.
 

Bartman

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#11
got back this afternoon from picking up the project parts. the fuselage frame is up at ACA and they're going to call in a week or so to let me know if they are going to work on it. the shop manager, Pat, looked at it with me and there are a few bent tubes in different locations. one may require a compete floor replacement and another may require the strut attach fitting to be ground off done from scratch. I wanted it to be done 100% correctly so if they end up saying they don't want to touch it then I accept that as the outcome.

the parts are a mixed bag of really good and really crappy so there will be many hours sorting through things just to decide what goes and what stays. multiples will be sold for project money.

i'm leaning towards new wood spar wings, 150 hp, and a fixed pitch prop. it was pointed out to me that that is about the lightest a Decathlon can be built and it's still very sporting with max useful load for day tripping. in the event I come upon a pile of cash I think that new, unflown wood spar wings with ailerons will be worth enough to make it worth selling them. the 150 hp core I have might be a good candidate but there aren't any logs, opinions welcome.

what's interesting is that a lot of the parts appear to be very low time. the top cowling piece has a crack but the holes are all immaculate. weird.

definitely low panel and I might spring for aluminum gear, not sure since I have seven gear legs to choose from and they're paid for!

i also have a Champ gear leg if anyone is looking for one.

nice to be home!
 

Bruce

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#12
You are a brave one to buy a true basket case, no logs are interesting first I would see if you can contact prior owner, then you can go on line and order all the 337 that have been filed with the faa. This will give a general idea of hours, age at time of repair or alteration and hours. As for airframe time if ACA give you thumbs up on frame and your rebuilding wings time really only hurt resale, if like me and you plan on flying the value out then who cares about log other than motor. The motor time would be nice to know just as reference aka confidence. Wish you the best and hope to meet in Fl.
 

aftCG

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#13
With a basket case I would be far more concerned with present condition than anything the logs might have shown.
The real Hobbs meter started when the plane left the factory and is most impacted by where it was parked and incidents that bent those tubes.

I wonder if you could build a legal decathlon without electrical system. No battery, starter, alternator, cables. A solid 100 pounds at least.

Ever notice how pretty much every 65hp champ has a higher useful load than any Citabria ever made?

Bonus points, does anyone out there know how max gross weight is chosen? Hint: it's not structural.
 

Bob Turner

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#14
On the times: you do not need logbooks. Start a new log. Do the required research, then start your logbook wit the total time your research revealed. Do not estimate! Do not round off!

How did you get zero time wood spar wings? Did it crash at the factory?

Same deal with airframes. You absolutely need total time; you do not need logs.

For those of you with logs starting with "estimated time 3000 hours" - do the research and correct that. It is easy now, and will be horribly complicated if you run into the wrong IA or airworthiness inspector.

And just to make sure you understand me - you must do the research. I am not suggesting falsifying records.
 

Bartman

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#15
new spars would come from Rainbow, I'm saying if I start by building up new wings with Rainbow spars I can always sell them later if I come up with the cash for new factory wings.

i have logs and a data plate for the airframe but nothing for the engine. the engine is so far down the list I can worry about that in 2022! lol

got your point though, will do what I can to validate the logs