PHall

+1

PHall

I would cut the cowl back on to match on both sides. They say that the exist should be 3X the inlet. Have you flown without the cowl? Did it over heat?

I helped with a project once that involved over heating and what we found was that there was a side of the engine that did not have airf flow although it was a nice open design. Directional veins were added and the problem was solved. So open area is not always the fix.

cessnaflyer54

My Feedback: (68)

The Warbird prop is alot more load on the motor than you think. You are right to drop down to the Xoar 22x10 sword. It will help because the blade is narrower than the warbird prop, and a retune will help. If you are still running the DLE carb, make your adjustments very small. The don't like 1/8 to 1/4 turns.

Valve floater

Cessna, I ordered a sword 20-10.

Michel

Now you're talking ,...............Up the RPM ,............... go get the HP

Michel

Rosster6028

My Feedback: (57)

Valve Floater - i think you have it there with the last pics of the cut cowl. Just smooth out the edges of the cowl so you don't cut the living daylights out of your hands! Don't forget to keep an eye on those needles now if you adjusted them like the other guys said...

fred985

be sure tobuild a small air dam just infront of the air outlet. this will make a negative air-pressure so the air will be sucked through the cowl. without the dam you wont get to much air-flow.

Truckracer

My Feedback: (19)

OK, this is the place where you will probably be offended but you come here for advice so here goes. The cooling arrangement on this plane looks horrible. The exit area is small and I see nothing about the cowl that would tend to produce a low pressure area behind the head that would help extract the hot air and promote cooling airflow through the cowl. The air could however backup ahead of the firewall above the cowl and just stagnate there then at best, just spill out. The carb is tucked way up there where at best the air will be hot and stagnant.... with the only airflow being from that which is ingested by the carb.

Ok, criticism is worthless without suggestions for improvement. Simplest thing you could do to improve the situation would be to open up the bottom of the cowl behind the cylinder head. Then, a small air dam or downward protruding lip about the width of the cowl and hanging down maybe 1/2" or 3/4" could be put on the cowl just behind the head to produce a low pressure area behind the lip. For illustration, this would be similar to open cowl flaps on a radial engine cowl or the radiator air exit on the bottom of a Mustang. The key here is to do whatever is necessary to produce a low pressure area behind the engine so the air is drawn through the cowl to the exit. Don't rely on that air just getting out of the cowl by some sort of magic through a hole, it must be extracted from the cowl by producing a low pressure area for the air to flow to. Just about every full scale airplane flying uses this principal for cooling. There are other issues such as cylinder baffles, etc. but I will not go into them here.

Another thing you could do would be to open up the bottom of the cowl as suggested before then install one of those aluminum louver panels with the openings facing rearward on the bottom of the cowl. These are like you see on a Sukhoi or YAK cowl. Anything would be better than nothing here. The secret here is changing ones thinking. Many people seem to think if the cylinder fins are hanging out in the breeze or the front cowl openings are large, the engine will cool and in many cases, that works. But in reality its all about airflow through the cooling fins and removing that heated air from the cowl by providing that low pressure area behind the engine for the air to flow to.

Prior to his death, Pe Reivers was on this forum regularly and helped many people solve their cooling issues. He often posted diagrams that illustrated both good and bad cooling techniques and I'm sure they're still archived in the past pages of this forum. Do some simple searches under his name and you should be able to find them. Some of his simplest fixes worked extremely well and as suggested, a simple change in ones thinking about how cooling works in our airplanes helps solve most cooling issues. I credit him for putting me on track some years ago!

rvnrcer

My Feedback: (4)

What about making an opening at the bottom right behind the scale air intake scoop, through the fuselage, not the wing? the full size Mustang has an adjustable opening here and would to very easy to duplicate on this model. Since the firewall has an opening already, this would allow air to exit through the fuselage. That is what I am planning for my Mustang/DLE 55 combo. I also think engine needs to be richened up.

Keith

Truckracer

My Feedback: (19)

The scale radiator air exit could certainly work on a Mustang. I'm surprised more people don't go that route.

Zeeb

My Feedback: (41)

Oh ugh... I hate to see guys chasing this issue but it happens pretty frequently on Warbirds.

FIRST! Flying one with the cowl off will NOT produce lower cylinder head temps unless the cowl setup was absolutely horrid.

Second; not only do you need to pay attention to the outlets and doing something to create a low pressure area there will always help.

Third; if that puppy is running hot besides the mention of getting rid of some of the load and verifying carb needle settings. you NEED SOME BAFFLING......

Baffling not only directs the airflow around the cylinders and toward the exits, but it SLOWS DOWN THE AIRFLOW. IF the air is moving too fast it cannot absorb heat very well. If you don't believe baffling is critical, take a few minutes and look for pictures of the baffling on full scale airplanes and I'm sorry to tell you, but there's no "3 to 1" rule on them in fact most have variable outlets in the form of cowl flaps to change the flow according to the load.

JMHO.....

karl hibbs

My Feedback: (6)

Hey Valve, I am using a dle 55 side exhaust,I don't know how much time you have on your engine but they do take awhile to break in so maybe give it some time and run it just a little rich.

Truckracer

My Feedback: (19)

Good points Zeeb! I mentioned baffling but didn't want to go further into the subject. Even if one provides just enough baffling to insure that most of the airflow is through the cooling fins and not just over the top of them, most engines will cool quite well. That can be fairly easy to accomplish in a tight cowl such as on a Mustang compared to a huge aerobatic airplane cowl.

I can almost guarantee, that if one were to disassemble the DLE55 from that Mustang, you would find coked on oil / carbon on the bottom crown of the piston. That is inside the piston above the wristpin! You only get that from running too hot and while needle settings are important, no needle setting other than slobbering rich will prevent that and keep the engine cool. Of course,running too rich presents its own set of problems with a gasser.

Valve floater

Thanks for all the advice. This is my first warbird so I am learning. So truckracer I like the idea with the scoop behind the fins. At a slight angle to shove the air to the top of the cowl? You are right. I wish I could put something to get that dead air at the top rear of the cowling. I would hate to put non scale vents or holes. Any ideas? Thanks

Truckracer

My Feedback: (19)

It wouldn't be a scoop but just a lip or vane of sorts that sticks down from the cowling and is angled back at the bottom. Think of it as one fin from a heat register (do they have those in Louisiana?) such as you might have in your house, attached to the cowl and angled back at the bottom. Its only purpose is to reduce the air pressure behind it so the air is drawn more thoroughly through the engine cooling fins and presented to the cowl opening behind it. I'll try to get some illustrations and post them here as my word descriptions really are not that clear.

Go here:
http://www.rcuniverse.com/forum/gas-...t-results.html

TonyBuilder

My Feedback: (11)

Baffling is your best bet for cooling, easy and works great. remember you need twice as much exit air as incoming air.

TB

3136

This does indeed work well, I merely cleared a big enough opening in my cowl to accomodate the fins and spark cap.
The chin block had a negative pressure vent to draw hot air, and the rear scoop which has a negative pressure zone by design had another vent to draw heat from the canister and engine bay.
This setup works well, you can thrash the living daylights out of it in an Australian hot summer and it runs like a top, and has done for years.
The 3 to 1 rule is b/s, the air needs to flow in the correct manner.

Valve floater

Looks good 3136. Is that a tuned pipe?

Truckracer

My Feedback: (19)

Valve floater, did you check the link I referenced?

http://www.rcuniverse.com/forum/gas-...t-results.html

kochj

Holy......

You have a PIPE in their!!!!

That should have it's own thread on it's own!.....
Let's see some pictures of that PIPE/cannister .eeerrrhumm... I mean cowling for engine and pipe....
Specifically ...lets see some picts of the PIPE...
I am interested in how it went through....

Valve floater

Thanks truckracer. I read through the link. When I get the 20-10 sword prop I am going to pull the cowl off and try to see if I can add something. Also will retune for the 20-10 prop. I would like to add 1 louver vent to the back top of the cowl also, but that may not look good.

fred985

go to RCV engines web site. look around in the model engine part and you will find a real simple inside cowl air directing box to build for the p 51 for cooling the cylinder.. they take overheating of their engines very seriously and state that the p 51 can be tricky to make sure the engine doesnt overheat.

Valve floater

Ok. thanks

Valve floater

I am thinking about drilling out some of the exhaust stack holes. This will help pull some air out higher in the cowl. And won`t look bad.

Truckracer

My Feedback: (19)

That could help!