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Post by n3480h on Aug 26, 2011 19:33:13 GMT -5
Granted, the Sonerai is already a fairly "slippery" aircraft when compared to most other amateur built types. My IILS will never be a serious racer, but that does not lessen my interest in further reducing drag to improve efficiency. What have you done that yielded a noticeable improvement? I read that anywhere there is a 90° or tighter angle, such as top of the wing to fuselage juncture, fairings can reduce drag. We can airfoil the gear, add lightweight wheel pants, and gap seals. Obviously, there is a weight penalty for every single item added to the airframe, but there must be more ways to reduce drag which will provide a net gain in spite of small additional weight.
Let's hear your thoughts and ideas.
Tom
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Post by schrome on Aug 26, 2011 19:46:20 GMT -5
Hi Tom,
Mine picked up 1-2 mph just by sealing the wing root gaps with tape. Proper fairings would yield more, I'm sure, but that project is farther down the list. I'm convinced there are improvements lurking under the cowling (better air flow management) and I've begun working on them but haven't realized them yet. Juergen had good ideas in his picture gallery on Sonerai.net.
Ed
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Post by raceair on Aug 26, 2011 20:10:18 GMT -5
Tom...There's several areas where nice fits will help, but to start with,..A good set of vertically split wheelpants really help....Vertically split are better, as they allow you to fit the front and back halves very close to the tire, wheras a pant that just pops over the top of the tire has to have a large enough hole to get over the tire, but when down where it belongs provides large entry holes for air to get in and swirl around inside the pant....
I also rivet a piece of inner tube to the front lower opening edge, which actually rubs right against the tire....Ed
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Post by n3480h on Aug 26, 2011 21:06:33 GMT -5
Thanks Ed and Ed, good suggestions. Makes me think about the right angles in my cooling plenums, uhgg. And the wheel pants I have are the pop over the top type. You are right, there has to be a huge gaping draggy hole in them to fit over the wheel. I'm making a list of winter projects I can build in the house while we enjoy our horizontal blizzards in Iowa. Really like the vertical split idea and the flexible wheel pant gap seal, common sense. And pretty easy to fabricate. Recently, I am looking at the stock cowl cooling inlets - not very efficient, I think. Glass work is never pleasant, but the result can be very worthwhile.
Keep 'em coming!
Tom
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Post by schrome on Aug 27, 2011 6:59:27 GMT -5
Two Eds are better than one, Tom.
;D
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stick
New Member
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Post by stick on Sept 1, 2011 12:27:25 GMT -5
Kent Passeur (sp?) has a great book out called 'Speed with Economy'. He explains a number of mods he makes to his mustang (not the P51). I bet a number of those mods would work for sonerais as well.
Mike
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Post by Schmleff on Sept 1, 2011 14:25:24 GMT -5
indeed. I have read that book many times. Its a must read for drag reduction.
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stick
New Member
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Post by stick on Sept 1, 2011 16:56:08 GMT -5
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Post by raceair on Sept 1, 2011 19:44:04 GMT -5
My old Cassutt had them. Builder Nick Jones had a lot of trouble with the linkages, and a couple times he even forgot to open them, which makes a nice little hole in them at touchdown....
Personally, I think the performance claimed increase is exaggerated......... But I'm not surprised......Ed
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Post by n3480h on Sept 1, 2011 19:51:36 GMT -5
Good information. The BD4 pants idea is pretty clever, though I might opt for electric (RC servo) operation for less weight. And a panel mounted LED retract indicator coupled to snap switches to prevent landing with the doors closed  . Going book shopping. Tom |
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Post by n3480h on Sept 1, 2011 20:03:12 GMT -5
Ed, landing with the doors closed was my first thought - I'd do that. But I can think of at least two ways to prevent that. Bet that was noisey when it happened, lol.
Tom
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Post by shawnson on Sept 2, 2011 13:58:03 GMT -5
those pants look like a pretty slick set up, if you told me i could get 12kts by pouring bacon grease on my plane i would break out my skillet right now... but i think raceair is right, i am sure there is some reduction there but not 12kts. dont mean i aint going to try it when i get to that point though
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Post by n3480h on Sept 2, 2011 14:27:32 GMT -5
Gave this some thought, and I think Ed F provided a better (and safer) solution in an earlier post. Vertical split pants with fixed, somewhat flexible "seals" would be a lighter, less complex way to go. I think 3-4 mph may be available with some thoughtful fabrication and careful material selection. This would be inexpensive and worth doing. I think even 2-3mph with very little weight gain would be huge.
As to the claimed 14 mph gain, I'd have to fly a course myself to believe it.
Tom
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hans
Full Member
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Post by hans on Sept 5, 2011 10:54:54 GMT -5
12 mph speed increase over what? Over a naked gear or over conventional wheel pants? As an aside: Kent Paser's book is cool - highly recommended. |
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Post by oahupilot on Sept 6, 2011 17:34:46 GMT -5
If you do just one or two drag reductions they wont be very effective by them selfs, you need to do as much as possible to get the most effectiveness out the individual mods. So if you had a plane that all you did was wheel pants you might get 5 to 10 knts, but if you had a plane that had wing root fairing, gap seals, super smooth and polished paint, optimized cooling drag, etc and then you installed wheel pants you might get a 10 -15 knt improvement on just the wheel pants. If you where only going to do one mod for drag reduction I would say load an inline 4 cycl water cooled engine with a 150 hp. The cooling drag from cooling the radiator will be less then cooling drag of the aircooled vw. I am positive you will get more then a 10knt increase with that mod  wheel pants would be the next best thing |
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