Message-ID: <000701c3b022$cb317aa0$1427fea9@randypc>
From: "Randy Echtinaw" <rjechtinaw@ia4u.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2754099@logan.com>
Subject: Re: [FlyRotary] Radiator size
Date: Fri, 21 Nov 2003 06:29:55 -0500
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Marc,
    There is another rotary list at   Home.earthlink.net/rotaryeng/
There has been doing a lot more radiator/duct design/experminting especially
by Paul Lamar. You would probably get more results to your request at this
site.
    I will be very interested in your book when it comes out. Be sure to
advertise it on both these sites.
    Thanks, Randy

----- Original Message -----
From: "Marc de Piolenc" <piolenc@mozcom.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, November 20, 2003 11:06 PM
Subject: [FlyRotary] Radiator size


> Dear Listmates,
>
> I've been a lurker on this list for some time, monitoring it for
> information on aircraft rotary engine installations. I've learned a good
> deal, but haven't had much to say. I'm chiming in now because the topic
> is one that I am studying intensively in order to write a book about it.
>
> I'm co-author of the first in a series of books about ducted propulsors,
> called (appropriately enough) Ducted Fan Design, Vol. 1. It presents a
> very simplified method of designing ducted fans and propellers in which
> the duct or shroud length is at least equal to the diameter of the
> rotor. Subsequent volumes will deal with short shrouds and other topics,
> but volume 2 is now reserved for cooling systems. This was originally
> supposed to be just a chapter or two in a book devoted primarily to
> propulsion, but as I did my research I discovered that, just as
> aerodynamicist Bruce Carmichael had said in his book on drag reduction,
> there is a huge gap between what cooling systems should cost in terms of
> drag and shaft power, and what they actually do consume. Even more
> surprising, even people who devote their whole lives to reducing drag,
> more often than not have only a vague empirical notion of how to achieve
> that with cooling systems. Hence in an airplane where external drag has
> been carefully optimized, a large increment in performance is often
> still available from improving cooling drag. Better still, the cooling
> effect can usually be improved as well.
>
> Good information was available in the past on this subject for those
> willing to dig for it. Some engine design texts could teach optimization
> of the coolant side of things, while a few aerodynamics texts - notably
> Kuechemann & Weber's _Aerodynamics of Propulsion_ - could teach radiator
> installations. All that is out of print. What is more, putting all the
> necessary guidance into modern language and in one consistent notation
> should make Volume 2 more accessible in every sense. So much for the
> commercial.
>
> There are a lot of questions on the list about the proper size for a
> radiator, but it is far more important to define the cooling duct's
> parameters first. The only mention of the duct in the latest digest of
> messages concerned the inlet, but the EXIT of the duct is far more
> important, because that and the pressure drop through the radiator
> control, in the final analysis, the mass flow through the radiator - and
> that is what produces the cooling effect. It is possible to spoil the
> effect of a good exit by poor inlet design - by making the inlet lip too
> sharp or cambering it the wrong way - but it really takes an effort! I
> doubt there is anybody on this list whose inlet is wrong.
>
> The proper duct parameters, in turn, depend on the pressure-drop and
> heat-transfer characteristics of the radiator core, as expressed in the
> modification of Miley's equation that I used in my article published in
> Contact! issue number 62. Two parameters are needed to express a
> particular core's presure drop characteristics, and another two for heat
> transfer. Each relation requires only two measurements to determine the
> two parameters, since the form of the relation is known. What's more,
> the pressure drop measurements can be carried out with no heat transfer
> taking place, as there are procedures for correcting for the occurrence
> of heat transfer in designing the duct. For heat transfer, obviously,
> entry and exit temperatures DO need to be taken for both the coolant and
> the air, simultaneously with the pressure drop and flow rate. Even so,
> these can be taken at the SAME two speeds previously calibrated for the
> pressure drop measurements. As a result, both the test rig and the test
> procedure can be simplified by comparison with NACA's early radiator
> installation test rigs, which may have inspired Rube Goldberg.
>
> The only problem is, I don't know anybody in the amateur-builder
> community who is doing this, and I don't know whether the cores that you
> folks are using come with the necessary information already provided by
> the manufacturer. It is, after all, much easier to pick two points off a
> plot than to derive them from tests... I would very much like to know,
> because aside from needing to give valid guidance in volume 2, I will
> soon be starting on a hovercraft project for a Catholic parish located
> upriver from town and needing reliable transportation for farm goods one
> way, building materials the other way. Although I'll be buying plans for
> a proven h/c design, I will still be on my own where radiator
> installation is concerned, as the hover crowd are at the pre-1921 stage
> of development where a bare radiator was thought to give the best
> cooling effect.
>
> If anybody out there has manufacturer's pressure drop and/or heat
> transfer data for a core or finished radiator that he could scan and
> send me, I would be most grateful. It doesn't matter what core - I just
> need to test my work so far against real hardware currently on the
> market.
>
> Regards to all,
> Marc de Piolenc
> Mass Flow
> http://www89.pair.com/techinfo/MassFlow/ductbook.htm
> --
> "The troops returning home are worried. 'We've lost the peace,' men tell
> you. 'We can't make it stick.' ... Friend and foe alike look you
> accusingly in the face and tell you how bitterly they are disappointed
> in you as an American. ... Never has American prestige in Europe been
> lower.... Instead of coming in with a bold plan of relief and
> reconstruction we came in full of evasions and apologies.... A great
> many Europeans feel that the cure has been worse than the disease. The
> taste of victory had gone sour in the mouth of every thoughtful American
> I met." --Life Magazine, January 7, 1946
>
>
>
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