Spam Can IA worries about BC12-D

[Karl Rigdon]

Re: Spam Can IA worries about BC12-D

Bill,
I am sure what Forest was saying the short cowl and/or nose bowl that was used on the ace model failed inspection and was from the reject or reclaim stock.

Karl

[Forrest Barber]

Re: Spam Can IA worries about BC12-D

The bottom Bill, the bottom, it really did not have much of a lip and of course no louvers, Most were replaced quickly or a lip added. The larger hole in the nose cowl was supposed to make up the difference.
I do not agree since you must "draw" the air through the baffle system , not "push" it! sure they had baffles maybe not all of them!
Did all your Tcrafts have the under crankcase baffle that attached above the carb spider and went forward to the "mouth" under the prop hub... I bet not!! That baffle let the air flow go back to the oil tank. It is one of the biggest violations of the old "conforms to Type Certificate" issue that I have seen out in the field. Happy holidays, and yes there were 3 fits of boot cowl to nose cowl combinations at the factory remember that old ( +/- 1/8th in.) over all tolance , it had to be made up somewhere.

[M Towsley]

Re: Spam Can IA worries about BC12-D

Forrest,

My '46 DID have that under crankcase baffle, however, my L-2 does not. The gentleman who restored it used a totally different way of 'pressurizing' the heat muff. Can those under the crankcase baffles still be obtained???

[crispy critter]

Re: Spam Can IA worries about BC12-D

Forrest,
Crispy also had the same baffle going back to the oil pan. My father always said the only thing he knew wrong with the t-craft was the poor baffling because even after they re-made all the baffles it still ran a little hot. Most of the t-crafts I've had never had this baffle and none of them ran hot. Someone told dad once that the oil pan baffle could cause problems.....do you think this would do it? We have been trying to decide weather or not to put it on the O200 with the short mount,I know the F-19's don't have it so we had planned not to make one for it......what do you think?

[alwaysoar]

Re: Spam Can IA worries about BC12-D

I'm baffled. Is Forrest saying there should or should not be a crankcase baffle? Does anyone have a photo or drawing showing proper baffling for the -65 installation?

Ed @BTV VT
TF 527

[Ron Greene]

Re: Spam Can IA worries about BC12-D

The attached drawing is for an L-2M not a BC-12D however at the bottom of the drawing is part #DCO-A6063 which is the crankcase baffle for this application. I only assume it is similar on a BC-12D.

My L-2B does not have the required baffle installed.

Ron Greene

[Dick Huish]

Re: Spam Can IA worries about BC12-D

The baffle is made in two parts. The rear part comforms to the bottom of the engine and the front part is made according to the cowling i.e. it is different for open cylinders as opposed to the full cowling. I made them using a Cessna 140 which is flat under the engine. Works a lot better than none. I don't know if I still have the pattern. Your cowling should have a scoop at the bottom of the opening and the chin baffle goes under it with a felt strip attached for a seal to the cowl. Dick

[M Towsley]

Re: Spam Can IA worries about BC12-D

Dick,

I am going to have to send you a picture of what mine looks like, it is definitely a bit convoluted compared to a stock B. The other B model, Mike's mechanic's, is all correct from what I can tell.

[alwaysoar]

Re: Spam Can IA worries about BC12-D

Thanks Ron--That's what mine looks like on my BC12-D. My temps are all in the normal range, 160+ on the coldest days, 180 on summer days. Must be properly baffled, right?

[Forrest Barber]

Re: Spam Can IA worries about BC12-D

Good answers , yes the D & B are a wee bit different, I have two here for patterns. The F-19 had no "mouth" under the prop hub , soooo the baffle was not used!
THAT is a long story posted somewhere on this huge forumn.

[VictorBravo]

Re: Spam Can IA worries about BC12-D

My mistake. I thought by "shorter cowl" you all meant that the fore-aft distance between the nose bowl and the firewall was shorter on the Ace. I would have PAID to see how they did that.

My airplane HAS the lower crankcase baffle, and I HAVE tried to do without it before... a very quick lesson.

Even with the lower baffle, when I tried to fly with a passenger this July on a hot day (100+), the oil temp was redlined within 5 miles of takeoff. So I vowed to tighten up the baffling or find some extra cooling somewhere before I flew it again in hot temps.

This is why I bit off more than I should have been chewing (yes, again) by making a new improved set of baffles. This is what I've been working on for some months now while waiting for the skylight approval to be done. I'm closing in on getting the baffles done this week. When the high temperatures return and this new baffle design is proven or disproven, I'll report it to the group.

Forrest is correct in that the cooling system should be "pulling" the air out the back rather than pushing it through the front.

My GUESS is that there wasn't very much known or studied about efficiently cooling of the Continentals back in the 30's. The size and shape of the inlet/outlet and other factors affecting the cooling are not very well thought out on the T-craft IMHO. Although it is a little easier on the crankshaft to have the propeller close to the front of the engine, it is not very good for making a low drag and evenly distributed cooling system. The prop should be as far out in front of the cylinders as possible, so you can have a small opening and a smooth "diffuser" inlet, leading to a smooth "plenum chamber" over the top of the engine.

On the port side forward cylinder, having the inlet air run into a vertical wall at full flight speed, diverted 90 degrees up, then having to make an immediate 180 degree reversal over a small or non-existent radius to go down through the cooling fins is just terrible. The starboard side is only marginally better, allowing a one or two inch radius at the top of the baffle.

The signature "triangular smile" of a Taylorcraft is one of the defining shapes of the design, but it's all wrong from an aerodynamic or thermodynamic point of view.

OK, turn rant switch off, I love the airplane regardless.......

[Forrest Barber]

Re: Spam Can IA worries about BC12-D

where were you when we tried to explain all this to the engineer for Dorothy thah could not understand cooling. The first baffles ( closed cowl) were done over night and passed the tests on the way to Miami in the Winter time from Ohio. they just kept using them. Then the F-19 with no lower baffle did better without the "mouth" ; we found this out the day before the tests for the FAA, I flew the tests with a piece of metal duct taped over the hole. She passed and we never looked back. Heavier oil for you!

[dedrekon]

Re: Spam Can IA worries about BC12-D

Marty (et al),
I have some excellent blow-ups of the L2 on my website on the Taylorcraft memorabilia page. Here's a pic of the baffles:

[Forrest Barber]

Re: Spam Can IA worries about BC12-D

That is the Model D under baffle, a wee bit different from the B . We have a couple here at Barber Aircraft. e-mail me direct [email protected] also have one side of the open baffle.

[flyguy]

Re: Spam Can IA worries about BC12-D

I'm having a little problem believing that the baffle inproves heating in the winter and cooling in the summer. I guess it would sound better if I said controls the temperature better in both hot and cold weather.
Mine with an 85 sometimes runs a little warm in the summer, but I have to cover up most of the front hole to get the oil over 125 even in poor excuse for cold weather that we have out here. No baffle.
As I used to work with such stuff (standards) I have always wanted to do a flow, pressure, and temperature analysis of the cooling "system" on my airplane, but have been a little concerned about getting a really functional static source for reference. I suppose a well designed commercial static source out in front, clear of everything, would do the job. The one from inside the wing sure varies all over with airspeed. Make a challenging summer project.
DC