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NeilsenRM(at)comcast.net
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 Posted: Thu Aug 07, 2008 12:29 pm Post subject: Aircraft Drag Componts |
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I attended a presentation of "Light Airplane Drag Reduction by Barnaby Wainfan at Oshkosh. Barnaby did the Kolb Xtra fuselage design. The following chart was shown:
Drag Horsepower of common Aircraft Components
150Knots 200Knots
500 x 5 wheel/tire.................. 2.5HP 5.8HP
Rotary Beacon Light............. 2.1HP 5.0HP
2in. exhaust (6 inch long)..... 1.5HP 3.5HP
7/8" spring gear leg (1 foot) 1.3HP 3.1HP
Tip Strobe (each).................. .8HP 1.8HP
1/4in wire (1 foot).................. 1.7HP 3.9HP
1 in tube (1 foot).................... 2.8HP 6.6HP
Rivets (round head: 100)....... .4HP .9HP
Bolts (AN3:10)....................... .2HP .5HP
Rivets (flat protruding: 100)... .05HP .12HP
The real eye opener is the 1/4 inch wire. Also our gear legs are shorter than most other planes but he said that frequently people will put wheel pants on the wheel and not the gear legs. The gear legs will often have more drag than the wheels. A very interesting presentation.
I asked him why VG aren't very very dragey. He said that VGs reattach airflow over a wing which off sets some of the drag of the VGs. He also said that the airplanes that use them are normally so aerodynamically dirty that the extra drag isn't noticeable.
Rick Neilsen
Redrive VW powered MKIIIC
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slyck(at)frontiernet.net
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| Posted: Thu Aug 07, 2008 1:48 pm Post subject: Aircraft Drag Componts |
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Rick, thanks for the numbers. That reinforces my belief that streamlining the gear legs is moreefficient than wheel pants (spats). -also lighter and simpler although not as sexy.
All those pipes hanging out above and behind our gas tanks sure slow us down too.
I have considered a small external foil at the aft door opening to get the air around that point .
BB
On 7, Aug 2008, at 4:28 PM, Richard & Martha Neilsen wrote:
| Quote: | I attended a presentation of "Light Airplane Drag Reduction by Barnaby Wainfan at Oshkosh. Barnaby did the Kolb Xtra fuselage design. The following chart was shown:
Drag Horsepower of common Aircraft Components
150Knots 200Knots
500 x 5 wheel/tire.................. 2.5HP 5.8HP
Rotary Beacon Light............. 2.1HP 5.0HP
2in. exhaust (6 inch long)..... 1.5HP 3.5HP
7/8" spring gear leg (1 foot) 1.3HP 3.1HP
Tip Strobe (each).................. .8HP 1.8HP
1/4in wire (1 foot).................. 1.7HP 3.9HP
1 in tube (1 foot).................... 2.8HP 6.6HP
Rivets (round head: 100)....... .4HP .9HP
Bolts (AN3:10)....................... .2HP .5HP
Rivets (flat protruding: 100)... .05HP .12HP
The real eye opener is the 1/4 inch wire. Also our gear legs are shorter than most other planes but he said that frequently people will put wheel pants on the wheel and not the gear legs. The gear legs will often have more drag than the wheels. A very interesting presentation.
I asked him why VG aren't very very dragey. He said that VGs reattach airflow over a wing which off sets some of the drag of the VGs. He also said that the airplanes that use them are normally so aerodynamically dirty that the extra drag isn't noticeable.
Rick Neilsen
Redrive VW powered MKIIIC
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Dana
Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA
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| Posted: Thu Aug 07, 2008 2:29 pm Post subject: Aircraft Drag Componts |
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To put it in perspective, remember that the drag HP varies as the cube of the airspeed. Thus, at 100 kts, multiply the 150 kt numbers by 0.3. At 75 kts, multiply by 0.125 At 50 kts, multiply by 0.04.
50 kts75 kts100 kts150 kts200 kts 500 x 5 wheel/tire.................. 0.0930.3130.7412.55.8 Rotary Beacon Light............. 0.0780.2630.6222.15.0 2in. exhaust (6 inch long)..... 0.0560.1880.4441.53.5 7/8" spring gear leg (1 foot) 0.0480.1630.3851.33.1 Tip Strobe (each).................. 0.0300.1000.2370.81.8 1/4in wire (1 foot).................. 0.0630.2130.5041.73.9 1 in tube (1 foot).................... 0.1040.3500.8302.86.6 Rivets (round head: 100)....... 0.0150.0500.1190.40.9 Bolts (AN3:10)....................... 0.0070.0250.0590.20.5 Rivets (flat protruding: 100)... 0.0020.0060.0150.10.1
-Dana
At 04:28 PM 8/7/2008, Richard & Martha Neilsen wrote:
| Quote: | I attended a presentation of "Light Airplane Drag Reduction by Barnaby Wainfan at Oshkosh. Barnaby did the Kolb Xtra fuselage design. The following chart was shown:
Drag Horsepower of common Aircraft Components
150Knots 200Knots
500 x 5 wheel/tire.................. 2.5HP 5.8HP
Rotary Beacon Light............. 2.1HP 5.0HP
2in. exhaust (6 inch long)..... 1.5HP 3.5HP
7/8" spring gear leg (1 foot) 1.3HP 3.1HP
Tip Strobe (each).................. .8HP 1.8HP
1/4in wire (1 foot).................. 1.7HP 3.9HP
1 in tube (1 foot).................... 2.8HP 6.6HP
Rivets (round head: 100)....... .4HP .9HP
Bolts (AN3:10)....................... .2HP .5HP
Rivets (flat protruding: 100)... .05HP .12HP
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The dinosours died because they didn't have a space program! [quote][b]
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Possums
Joined: 03 Nov 2007
Posts: 247
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| Posted: Thu Aug 07, 2008 3:09 pm Post subject: Aircraft Drag Componts |
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At 06:24 PM 8/7/2008, you wrote:
| Quote: | To put it in perspective, remember that the drag HP varies as the
cube of the airspeed.
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I think the most bang for your buck is going to be the lift struts.
I could tell at least 4 to 6 mph top end with my old 447 Firestar.
I did the landing gear later and didn't really notice any difference, but
it looked neat. Those original little landing gear looked kind of goofy.
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JetPilot
Joined: 10 Jan 2006
Posts: 1246
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| Posted: Thu Aug 07, 2008 6:27 pm Post subject: Re: Aircraft Drag Componts |
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Those are very interesting numbers Rick. I would have never guessed that the landing gear tube would have more drag than my wheels. I will have to measure the length of my gear legs, but given your numbers I think fairings on the gear legs like I have on my struts might be worthwhile.
Mike
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"NO FEAR" - If you have no fear you did not go as fast as you could have !!!
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pj.ladd(at)btinternet.com
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| Posted: Fri Aug 08, 2008 1:41 am Post subject: Aircraft Drag Componts |
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He also said that the airplanes that use them(VG`s) are normally so aerodynamically dirty that the extra drag isn't noticeable. >>
Hi, surely that must be a bit tongue in cheek. They are appearing more and more on commercial airliners and I don`t think they could be described as `dirty`
Pat
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