---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Sun 12/03/06: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:45 AM - Re: Perfect cooling diffuser (Duncan & Ami McFadyean) 2. 04:24 AM - Cooling diffuser (=?UTF-8?Q?R=C3=A9mi_Guerner?=) 3. 06:35 AM - Altrak (Michel AUVRAY) 4. 09:18 AM - Cooling diffuser (=?UTF-8?Q?R=C3=A9mi_Guerner?=) 5. 12:37 PM - Bird for sale (Sven den Boer) 6. 01:11 PM - Re: Perfect cooling diffuser (karelvranken) 7. 05:04 PM - Re: Cooling diffuser (Graham Singleton) 8. 05:50 PM - Re: Perfect cooling diffuser (GLENN CROWDER) 9. 09:44 PM - Re: Cooling diffuser () ________________________________ Message 1 _____________________________________ Time: 02:45:12 AM PST US From: "Duncan & Ami McFadyean" Subject: Re: Europa-List: Perfect cooling diffuser Gilles, Did you measure air temperature increase across the radiator (i.e. inlet air temperature and outlet temperature)? Which, in accordance with Boyles Law would dictate the inlet/outlet ratio; we are not in to compressibility at our speeds! I agree that the actual area of these is dictated by the size/type of radiator core and the amount or air that it is able to pass. PE Irving in his 1960's book ('Tuning of the Automobile Engine'(?)) stated that the inlet area only needed to be 1/6th (17%) of the face area of the radiator (with proper ducting) and cited the early E-Type Jaguar sportcar as an example. The XS inlet area is about 60%. Mine is 30% (77cm2)and works well. I did not have the nerve to make this smaller; preferring evolution, not revolution! But with the experience, it could have been a bit smaller, although I made no allowance for leakage around the sides of the radiator. My non-adjustable outlet area is 115% the size of the inlet; which was a guess but the measured air temperature rises suggest it could have been less. Rgds., Duncan McF. ----- Original Message ----- From: "Gilles Thesee" Sent: Saturday, December 02, 2006 1:20 PM Subject: Re: Europa-List: Perfect cooling diffuser > > > Duncan, > >> >> What is your ratio(s) of inlet area to outlet area? > > What really matters is the ration of outlet area to RADIATOR area. As > already stated on Contrails, too large an opening won't flow more air than > a correctly proportioned one, since it is the radiator that governs the > flow in the duct. > It may help to figure the radiator duct system as a duct with 3 valves in > series. The middle valve is the radiator. As it is partly closed, opening > the other valves more than necessary won't change the overall throughput. > There is no use opening the outlet more than about 1 time the radiator > frontal area, you would only add drag without increasing air flow through > the radiator. Drag decreases as you reduce outlet area by means of the > cowl flap. In cruise, outlet area should be smaller than the inlet area to > achieve minimum drag. It is advisable to construct the adjustable cowl > flap with a range of openings from 1 time the radiator area to near zero > (power descent on a cold day). > > In our setup, inlet area is 25% of the radiator frontal area, whereas exit > cowl flaps can be adjusted from 70% to 0% of the radiator area (410 cm). > We currently cruise with flaps adjusted to 18% of the radiator area, or > less on cold days. On summer hot days, best cruise (75% power) is with the > exit adjusted at about 28% radiator area. Of course we open more in a > prolonged climb. > > During flight tests I installed a data logging system to check adequacy of > the pressures and temperatures. > > Adjusting CHT and oil temps to within 5C of desired temperatures is a > breeze, and we found no special limitations concerning ground run time. A > thorough cooling study is really worth the time and hassle. > > Hope this helps, > Regards, > Gilles > http://contrails.free.fr > > ________________________________ Message 2 _____________________________________ Time: 04:24:16 AM PST US From: =?UTF-8?Q?R=C3=A9mi_Guerner?= Subject: Europa-List: Cooling diffuser Salut Gilles, My question regarding cooling on the ground is because all Rotax equipped Europas are known to overheat very quickly on the ground. I know some guys who say they do not overheat, but I have often observed them taxiing very fast to the holding point to be sure they are aloft before reaching the boiling point. Again the design of the Europa cowl is not optimal but cooling in flight is very effective. On the ground however it does not work properly. I am now convinced that the main cause for this poor cooling on the ground is the propeller. Most Europas are fitted with Warp Drive props or Airmaster hub Warp Drive blades combination. Those blades are narrow at the root and not very much twisted. Therefore they do not provide a lot of air flow where the air inlets are located. On the other hand, most MCR are using the MT prop whose design is just the opposite: very wide blades at the root and a lot of twist which is a lot more effective ventilator. My own fix for the Europa cowling is a variable air scoop, below the existing inlet, ahead of the radiator. Theoretically it is very bad, but it works! It works because this additional inlet is located farther from the propeller axis, therefore receiving more air flow. Sure this adds a lot of drag, but who cares about drag during taxi and run-up? The scoop is positioned back to neutral just before take off and can be closed to blank the radiators at cruise and descent at cold temperatures. Remi Guerner Europa F-PGKL No problem on the ground. During first run ups we ran the engine as long as 30 minutes continuous with several full power runs then fast idle periods. I did not take special measurements on the ground, only monitoring CHT during warm up, taxi, etc...The aircraft was test flown from - 14C to + 37C OAT. I can do take the measurements you require when flying with a helpful passenger, but since we're in autumn, you'll have to wait until summer for hot day conditions. Best regards, Gilles http://contrails.free.fr ________________________________ Message 3 _____________________________________ Time: 06:35:13 AM PST US From: "Michel AUVRAY" Subject: Europa-List: Altrak ________________________________ Message 4 _____________________________________ Time: 09:18:41 AM PST US From: =?UTF-8?Q?R=C3=A9mi_Guerner?= Subject: Europa-List: Cooling diffuser Salut Gilles, My question regarding cooling on the ground is because all Rotax equipped Europas are known to overheat very quickly on the ground. I know some guys who say they do not overheat, but I have often observed them taxiing very fast to the holding point to be sure they are aloft before reaching the boiling point. Again the design of the Europa cowl is not optimal but cooling in flight is very effective. On the ground however it does not work properly. I am now convinced that the main cause for this poor cooling on the ground is the propeller. Most Europas are fitted with Warp Drive props or Airmaster hub Warp Drive blades combination. Those blades are narrow at the root and not very much twisted. Therefore they do not provide a lot of air flow where the air inlets are located. On the other hand, most MCR are using the MT prop whose design is just the opposite: very wide blades at the root and a lot of twist which is a lot more effective ventilator. My own fix for the Europa cowling is a variable air scoop, below the existing inlet, ahead of the radiator. Theoretically it is very bad, but it works! It works because this additional inlet is located farther from the propeller axis, therefore receiving more air flow. Sure this adds a lot of drag, but who cares about drag during taxi and run-up? The scoop is positioned back to neutral just before take off and can be closed to blank the radiators at cruise and descent at cold temperatures. Remi Guerner Europa F-PGKL No problem on the ground. During first run ups we ran the engine as long as 30 minutes continuous with several full power runs then fast idle periods. I did not take special measurements on the ground, only monitoring CHT during warm up, taxi, etc...The aircraft was test flown from - 14C to + 37C OAT. I can do take the measurements you require when flying with a helpful passenger, but since we're in autumn, you'll have to wait until summer for hot day conditions. Best regards, Gilles http://contrails.free.fr ________________________________ Message 5 _____________________________________ Time: 12:37:09 PM PST US From: "Sven den Boer" Subject: Europa-List: Bird for sale I am putting my bird up for sale, moving to a 4-seater. http://www.planecheck.com?ent=da&id=6510 Nice detail, that this aicraft will be featuring in the January number of Aerokurier for a pilot report on the Trigear XS. Great fun, outperforming a C!82 ! Best Regards, Sven den Boer A169 PH-SBR ________________________________ Message 6 _____________________________________ Time: 01:11:55 PM PST US From: "karelvranken" Subject: Re: Europa-List: Perfect cooling diffuser Gilles, Glenn and all, Here some pictures of my cowl modification; indeed inspired by Mustang P 51. Karel Vranken. ----- Original Message ----- From: "Gilles Thesee" ________________________________ Message 7 _____________________________________ Time: 05:04:58 PM PST US From: Graham Singleton Subject: Re: Europa-List: Cooling diffuser Remi Another way to improve cooling on the ground is exhaust extraction, this is how the EZ boys do it. I don't think anyone has tried it yet on a Europa. You are right about the Warp Drive props. I had an Arplast PV50, nice smooth rnning prop and better cooling. Ernst Keppert has the fixed pitch Arplast which has the same blades and I don't think he has any problems cooling on the ground either. I should say he has Classic Europa, not quite the same Graham Rmi Guerner wrote: > > > Salut Gilles, > > My question regarding cooling on the ground is because all Rotax > equipped Europas are known to overheat very quickly on the ground. I > know some guys who say they do not overheat, but I have often observed > them taxiing very fast to the holding point to be sure they are aloft > before reaching the boiling point. Again the design of the Europa cowl > is not optimal but cooling in flight is very effective. On the ground > however it does not work properly. I am now convinced that the main > cause for this poor cooling on the ground is the propeller. > > Remi Guerner > > Europa F-PGKL > >* >* > ________________________________ Message 8 _____________________________________ Time: 05:50:22 PM PST US From: "GLENN CROWDER" Subject: Re: Europa-List: Perfect cooling diffuser That looks awesome Karel! Be sure to seal off all around the duct inside so incoming air can only go thru the rad. Managing air flow is like herding cats - if theres a way not to cooperate, they will find it! On my rad, I welded on aluminum angles all the way around the face of the rad making a fence about an inch tall to allow the duct to slip inside. No funky seals to monkey with! Glenn >From: "karelvranken" >To: >Subject: Re: Europa-List: Perfect cooling diffuser >Date: Sun, 3 Dec 2006 22:17:45 +0100 > >Gilles, Glenn and all, >Here some pictures of my cowl modification; indeed inspired by Mustang P >51. >Karel Vranken. >----- Original Message ----- From: "Gilles Thesee" > ><< DSC00001.jpg >> ><< DSC00002.jpg >> ><< DSC00003.jpg >> _________________________________________________________________ View Athletes Collections with Live Search http://sportmaps.live.com/index.html?source=hmemailtaglinenov06&FORM=MGAC01 ________________________________ Message 9 _____________________________________ Time: 09:44:48 PM PST US Subject: Re: Europa-List: Cooling diffuser From: Hello Graham "> Another way to improve cooling on the ground is exhaust extraction, this > is how the EZ boys do it. I don't think anyone has tried it yet on a Europa." How exact is exhaust extraction accomplished on EZ? How about spraying water on the radiator during extended ground operations and temps creep high, anyone try this? 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