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Joined: 12/30/2001 From: San Pedro, CA, USA Status: offline
Merlin, I will be entertaining ideas actually on this very subject soon. Ducting is gonna be mandatory in some fashion, using the small cooler opening as the intake and the larger one as the exhaust. maybe even using the carb intake under the leading edge of the wing. Any of you guys care to share your pictures of how you are cooling your inline twin set up, I would love to see them.
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Joined: 2/17/2002 From: MelbourneVictoria, AUSTRALIA Status: offline
Ray, I've been struggling with this one for years but if it's ideas you're after, here's a few I'll toss into the ring even though most may be totally impractical. 1. The "flap" method as used by B.Taylor. (Works well it seems) 2. Water cooling as per Randy Villines (Works well but plumbing on a Spit would be painful) 3. Ducting from the carb intake. (Not really practical unless the full size used the tropical filter, MK VIII onwards) 4. Using the lower cowling as a giant heatsink. (Mk1 to MKV had the oil tank exposed as part of the lower cowling and the extra weight of a large lump of aluminum wouldn't hurt the Spit) 5. P.C type fan and ducting mounted to the cyl' head drawing air from the carb intake. (Would need a mechanical power take-off to be reliable.) 6. Building a plenum chamber in the top section of the cowling to suck hot air from the engine bay and force exit via the exhaust stacks. Anyone else? -- Merlin
Posts: 207
Joined: 9/20/2003 From: AdelaideNot-applicable, AUSTRALIA Status: offline
Hi all, Have flown 1/3 spit of ml407 and she flies like Richard said like a **** cat if you want advice on cooling i would be happy to help flaps do not seem to be a problem let me know what you require.
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Joined: 12/30/2001 From: San Pedro, CA, USA Status: offline
quote:
ORIGINAL: morro
Hi all, Have flown 1/3 spit of ml407 and she flies like Richard said like a **** cat if you want advice on cooling i would be happy to help flaps do not seem to be a problem let me know what you require.
Cheers Todd
Todd, thanks for the offer, if you could snap a few pics of your cooling set up that would nice. I have twin cylinder, dont know if you have the same, but what ever the cooling set up you have, it would be appreciated if you would picture share it with me along with any narrative you can think of.
Jeff and Don, I know you guys have the same motor, could benefit from your inputs as well.
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Joined: 1/19/2002 From: Apple Valley, MN, USA Status: offline
Hi Ray...on the Clark, the chin scoop was used to duct air to the rear cylinder, but his set-up made it easy as the cowl sit over the from 1/4 of the wing chord. The cowl material was removed, along with the upper and lower wing sheeting, to match the duct pattern. Teh air flow was thru the chein scoop and was rebounded off the center shear webbing and ten moved forward thru and internal duct in the cowl that directed to the rear cylinder. Kinda hard to explain...maybe Don has a pic. As for the Merlin I engine...I found it to be a complete dud with the 3 bladed prop. It barely flew the plane at 42 pounds. The blades from Clark are cut from a 22x8 blade. This make a pretty flat tip that does not cut the air that fast....kinda like the old Byron 4 blade. I have this same engine in my 124 TBF and run a 26x10 or a 24x12 and it flies very well at 51 pounds. This engine was in a 12 foot Tony that turned a 22x14 3 blade. I think for that Clark engine, you will not be happy with anything less than a 24x12 prop. The 3 blade is too much load and lacking pitch for good speed. I sold my Spit. But, here she was prior to first flight.
< Message edited by F4u5 -- 2/4/2004 11:29:26 PM >
Posts: 207
Joined: 9/20/2003 From: AdelaideNot-applicable, AUSTRALIA Status: offline
Ray, there are various methods to cool this type of motor the one i have found to be successful is to cut the v shape out on the nose of the cowl and then have piped ducting going from the rear of the firewall out through the wing ducts i have found this to be very good and simple it sounds to be a boch up but when dealing with spits you have to find the simplest way possible i have this method on my 1/3 spit and have a 3w engine and have no probs with overheating
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Joined: 12/30/2001 From: San Pedro, CA, USA Status: offline
Todd, thanks for the info, I am wondering if I can run a combination of sorts with the v on the front cylinder and some ducting on the aft cylinder. Jeff, bummer, I think I can go ahead and get some blades made up by Zinger at different diameters and pitches.
Ray
< Message edited by AirRayInc.Com -- 2/4/2004 8:13:59 PM >
Posts: 207
Joined: 9/20/2003 From: AdelaideNot-applicable, AUSTRALIA Status: offline
Ray, I have a scale mag that shows the installation of piping for the cooling of the same motor if you are interested I will send it to you I think you will probably get bamboozaled about what people are saying about all of this but the idea to keep the weight down and simple, probably stating the obvious here.
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Joined: 9/20/2003 From: AdelaideNot-applicable, AUSTRALIA Status: offline
Ray, here I am again the prop size mentioned is right i currently run a 24/12 prop going onto a 26/12 these props are wooden and I have always used them 3 bladed props are only ideal for medium scale aircraft.
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Joined: 2/25/2002 From: Twin Falls,
ID, USA Status: offline
Ray, I'll get some pictures of mine in a day or two. The air intake is the carb intake and it bends around and ducts air to the rear cylinder and then out the exhaust openings. You can't make an opening in the front of the engine with this system as it will not allow the air into the cowl from the rear duct. I have the new Merlin II engine made from the Sachs engines. It came with a 26-10 three blade prop. John Clark also said to use a fuel additive called Metallon and to run the engine just a touch on the rich side. Don
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Joined: 12/30/2001 From: San Pedro, CA, USA Status: offline
And then the light went on! Don, that of course makes sense, as there is the space between the exhaust for hot air escape. I dont think the carb intake for the Mk1 is big enough, but with your info. I am not so stressed about it, I can use a combination of the two small intakes and route as you outlined.
Thanks in advance for the pictures, by the way, how is yours coming, should be done by now eh?
Todd, I would like to see your magazine pictures as well if you dont mind.
Posts: 820
Joined: 2/25/2002 From: Twin Falls,
ID, USA Status: offline
Ray, Mine is in the painting stage but I have a bunch of other projects going on. I'm in the middle of doing the fabric on my full scale Yak. Gotta get that done right away cause I can't stand not being able to fly. Also finishing up my micro DH-2 indoor electric. 21" ws will weigh around 85grams. I go the full spectrum. Don
Posts: 922
Joined: 12/30/2001 From: San Pedro, CA, USA Status: offline
Don, well what does one say to a full size Yak, other than, "can I go for a ride"? I had planned to reshape the engine box, now that I have done that and test fit everything, your input about the cooling makes total sense, there is actually room to duct it right onto the heads. Or so it looks like at the moment. Thanks Buddy,
Todd, looking forward to seeing your pictures, Thank you
Ray
< Message edited by AirRayInc.Com -- 2/5/2004 1:28:47 PM >
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