Chilton DW1 Build

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VP1

Todd C.
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I've been working blind! You can see how terrible my photos have been- that's lighting, not a particularly poor camera. Got a couple of 4' LED shop lights today. What a difference!


In other news- all of the major gluing operations are done for the tail. I still need to make the metal bits but I'll do that later. Also need to do all the finish sanding but i'll do that immediately before covering. Aircraft Spruce has my wing spar order and I hope to get going on that this month.
 

VP1

Todd C.
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Wouldn’t you know it.. got a call from Corona this afternoon. They have not only my spar order ready, but also the rest of the material for the wings which I placed the order for shortly after my spar order. I’ll go pick it up tomorrow. If anyone is curious all of the wood for the wings-with no scrounging or begging-is about 1300 bucks. Not too bad of you ask me. Of course it could be done cheaper buy buying local lumber but A- I feel better having someone more knowledgeable grade my wood and B- the majority of that cost is 1mm ply. (10) 1mm sheets to be exact and at least one of a few other thicknesses. I don’t know where else you’re going to find that birch ply.

Better get some glue
 

plncraze

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So does she think all parents build airplanes in the garage? Or that real airplanes are made of wood?
 

VP1

Todd C.
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Hey now! I’m trying to maintain her innocence for a few more years. I’m not ready to tell her just yet that not all airplanes are wooden taildraggers :)
 

Jan_K

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Engines....Ideally I'd use a Mikron III but they're $10,000 + euros and support seems very nonexistant. To be honest, I wouldn't really mind spending the money if the support was there, but without it the risk of having a $10,000 paperweight is too high for me. So.. that leaves the A-65, VW, or Rotax as the main contenders. Although I'm not very excited to admit, the Rotax 582 is currently leading my list of contenders. While I'm not crazy about the 2 stroke aspect, I do have a lot of experience with 2 strokes so I think I could manage one safely. Plus is would maintain the cowling lines.

VW- Flat 4 ruins the look.
A-65- heavy and ruins the look.

So... I don't know yet. Still making up my mind
What about using Suzuki Geo or similar 1300CC direct drive in the same manner as the original Carden Ford 1100CC side valve was - upright direct drive? Just to install one more ball bearing + some crank extension, you can have a smaller prop turning faster. 40hp@3900RPM had the original Chilton when updated for racing in 1950ties.
 

VP1

Todd C.
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Center section spars need to be cleaned up, varnished and close out sheeted, and then tapered.

Venting spars- Is there real need? I remember reading Mark Langford's KR build blog and he mentioned venting the built up spar so that it doesn't try to explosively vent itself at altitude. I really don't think thats necessary particularly when figuring the maximum altitude this thing will ever see is....not very much.. Thoughts?
 

VP1

Todd C.
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What about using Suzuki Geo or similar 1300CC direct drive in the same manner as the original Carden Ford 1100CC side valve was - upright direct drive? Just to install one more ball bearing + some crank extension, you can have a smaller prop turning faster. 40hp@3900RPM had the original Chilton when updated for racing in 1950ties.
Suzuki engines are an option, however not my first. Primarily due to weight reasons. Right now I'm crossing my fingers the O-100 will be done in time for her.
 

Chilton

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The original Chilton spars were not vented, so probably not worth worrying about.

Progress looks good.
 

n45bm

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Hi,
Aircraft grade sitka spruce is kinda pricey, I'm guessing. Are you getting your spruce from ASSCO? I got mine for my Corby Starlet mainly from Wicks, but that was long ago. I still have it after 31 years. It has an 1835 cc VW.
 

Jan_K

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I agree that the Suzukis are a great option for the proper period look. The $7,500 75 hp Aeromomentum AM10 or similar Suzuki G10 conversion seems just about perfect for this application. See http://aeromomentum.com/am10.html

Well I did not mean automotive engine with belt drive running permanently beyond its design limits, but a direct drive running at "highway" RPM and 40hp max. :)
...anyway, the O-100 appears as a good choice!
 

cluttonfred

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That seems like an overstatement. A Geo Metro (North American old Suzuki Swift) with a 3-cylinder 1.0 liter engine runs about 3100 RPM in 5th gear (manual transmission) and 3800 in 3rd gear (automatic transmission) at 65 mph/105 kph with a red line RPM of 7400-7600. Aeromomentum quotes their AM10 as making 75hp @ 6000 rpm (2318 prop rpm). If all you want is 40 hp max then you are talking substantially less at cruise, call it 30 hp. That seems to me that the AM10 ought to be able to do that at less than automotive highway RPMs and you'd have a lot more reserve power if you need it.

Well I did not mean automotive engine with belt drive running permanently beyond its design limits, but a direct drive running at "highway" RPM and 40hp max. :)
...anyway, the O-100 appears as a good choice!
 

Jan_K

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The original Chilton had 35hp, 40 hp had the updated Train engine version, I have seen the original 35hp Chilton, and definitely was not underpowered.
100mph cruise and 650fpm climb are more than enough in my eyes.
I do not believe to the reliability of any automotive conversion using reduction gear. The reason is car engines were not designed to run permanently at 75% of power. The main issues are engine heat transfer (particularly head) and material fatigue.
@VP1, I am sorry for hijacking the thread. I am looking for next build updates!
 
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cluttonfred

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Sorry, Jan_K, you are obviously entitled to make up your own mind about what engines you prefer, but your numbers are still not making any sense. How does 35-40 hp correspond to 75% power in a 75 hp engine? I get 47-53%.
 

Jan_K

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40hp is max power you can get from 1300cc DIRECT drive, if you take in account prop RPM limitations (3900RPM orig Chilton) This roughly equals european highway engine speed.
75% of max power is usually preferred cruise on aero engines. Makes no sense to use lower power, because a propeller (fixed) gets out of efficient range.
Problem of geared car engine is that at 75% it runs are above the max. continuous power=> fatigue, overheating
 

cluttonfred

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Except your argument seems to be comparing apples and oranges.... Even accepting your argument that the car engine should not be run at high rpm even for takeoff and landing, the AM10 run at just 50% power would still provide about 38 hp, substantially more power for less weight than the Chilton's original 31 hp Carden-Ford. The result would be a very smooth and quiet engine with the prop turning at just 1200 rpm (more if you change the reduction gear ratio). Why would that be a bad thing?
 
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