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by dlednicer
Sun Oct 24, 2021 2:21 am
Forum: Military Aviation & Space Flight
Topic: Protrusions on EC-135/E-3/AC-130 and Flight Stability
Replies: 4
Views: 642

Re: Protrusions on EC-135/E-3/AC-130 and Flight Stability

And sometimes, ventral fins aren't needed:

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by dlednicer
Sun Oct 24, 2021 2:12 am
Forum: Military Aviation & Space Flight
Topic: Protrusions on EC-135/E-3/AC-130 and Flight Stability
Replies: 4
Views: 642

Re: Protrusions on EC-135/E-3/AC-130 and Flight Stability

And, sometimes the added appendages do impact stability, so we add ventral fins:

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by dlednicer
Sun Oct 24, 2021 1:51 am
Forum: Military Aviation & Space Flight
Topic: Protrusions on EC-135/E-3/AC-130 and Flight Stability
Replies: 4
Views: 642

Re: Protrusions on EC-135/E-3/AC-130 and Flight Stability

Not all protrusions have the same impact. Objects with rounded trailing edges don't produce much lift or side force (depending on how they are oriented) and thus don't have much of an impact. The radome on the top of the forward fuselage of these aircraft has a relatively small impact on stability (...

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by dlednicer
Tue Aug 31, 2021 2:39 am
Forum: Technical/Operations
Topic: Question on Aerodynamic Center
Replies: 3
Views: 1104

Re: Question on Aerodynamic Center

The concept of Center of Pressure if fictitious. In a college course on statics, one of the first things you are taught about is a couple, which is two equal and opposite forces producing a moment with no net force. Most engineers seem to forget about this after the final exam. I was among the guilt...

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by dlednicer
Sat Jul 17, 2021 5:32 am
Forum: Technical/Operations
Topic: Chart of Jetliners with and without wing vortex generators.
Replies: 7
Views: 1014

Re: Chart of Jetliners with and without wing vortex generators.

The DC-9, MD80 and MD90 have a vortilon, which is a vortex generator, below each wing leading edge at roughly midspan. 1410145 DC-10s and MD11s have nacelle strakes, which produce a vortex that interacts with the wing flow field. As such, you could count them as wing vortex generators. A lot of othe...

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by dlednicer
Tue Jun 01, 2021 3:48 am
Forum: Technical/Operations
Topic: Russian Aircraft and Very Tall Landing Gear
Replies: 43
Views: 7435

Re: Russian Aircraft and Very Tall Landing Gear

Max Q wrote:
Can’t think of any negatives with a nice tall landing gear, it gives good clearance from the possibility of tail, wingtip or engine nacelle strikes and allows for easy fuselage stretches


A huge negative: weight

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by dlednicer
Sat Apr 03, 2021 11:01 pm
Forum: Technical/Operations
Topic: Why do some Stage III hush kits have ejectors in conjunction with a mixer instead of just a mixer only?
Replies: 2
Views: 2759

Re: Why do some Stage III hush kits have ejectors in conjunction with a mixer instead of just a mixer only?

On the GII/III you need an improved internal core/bypass mixer, an exhaust/external mixer and an ejector to meet the noise requirements. The RQLP GII hush kit started life with a retractable ejector, but they didn't meet the noise requirements, so the ejector was lengthened until they met the noise ...

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by dlednicer
Sat Apr 03, 2021 10:33 pm
Forum: Technical/Operations
Topic: Why did Boeing design the 707 to have a shorter landing gear than the DC-8?
Replies: 10
Views: 4225

Re: Why did Boeing design the 707 to have a shorter landing gear than the DC-8?

A Boeing old timer told me that they picked the height of the door sill above the ground on the 707 to match that of the DC-6.

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by dlednicer
Tue Dec 29, 2020 5:30 am
Forum: Technical/Operations
Topic: Technical Cheat sheet for aerospace and aeronautical engineers
Replies: 10
Views: 3508

Re: Technical Cheat sheet for aerospace and aeronautical engineers

I taught Applied Aero at Cal Poly earlier this year and recommended that my students become familiar with: Hoerner "Fluid Dynamic Drag" and "Fluid Dynamic Lift" Ed Obert "Aerodynamic Design of Transport Aircraft" Ted Lomax "Structural Loads Analysis for Commercial ...

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by dlednicer
Tue Dec 29, 2020 5:07 am
Forum: Technical/Operations
Topic: 747-400 vs 737 winglet size
Replies: 10
Views: 3215

Re: 747-400 vs 737 winglet size

https://img.geocaching.com/waymarking/d ... 80b753.jpg
-->

The surviving API 747-200 winglet is on display in front of the Museum of Flight in Seattle: https://img.geocaching.com/waymarking/d ... 80b753.jpg

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by dlednicer
Sun Aug 23, 2020 7:13 pm
Forum: Technical/Operations
Topic: 747-200F with blended winglets.
Replies: 18
Views: 4349

Re: 747-200F with blended winglets.

https://img.geocaching.com/waymarking/d ... 80b753.jpg
(I worked on the program)
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One of the remaining 747-200 proof of concept winglets is on display out front of the Museum of Flight in Seattle: https://img.geocaching.com/waymarking/d ... 80b753.jpg
(I worked on the program)

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by dlednicer
Fri Jul 31, 2020 4:20 am
Forum: Technical/Operations
Topic: 737 MAX Upper Fuselage Antennas
Replies: 6
Views: 2205

Re: 737 MAX Upper Fuselage Antennas

The picture of the United 737-9 MAX seen above shows it carrying a Boeing Tri-band Radome. Its 92.4 inches long, 11 inches high and 42.3 inches wide. Different antennas can be put below it. Gimbaled antennas are installed below it (in contrast to the semi-phased arrays used with the Gogo 2Ku). The a...

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by dlednicer
Mon Jul 13, 2020 1:51 am
Forum: Technical/Operations
Topic: 737 MAX Upper Fuselage Antennas
Replies: 6
Views: 2205

Re: 737 MAX Upper Fuselage Antennas

The only satcom radome available for line fit on the 737MAX is the Boeing Tri-band Radome. As Boeing notes "Sized to fit a wide range of Ku and Ka antennas from Panasonic, Honeywell, ViaSat, Global Eagle Entertainment (TECOM), and others."

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by dlednicer
Mon Jun 22, 2020 12:45 am
Forum: Technical/Operations
Topic: Fokker 60 questions
Replies: 5
Views: 2970

Re: Fokker 60 questions

The Fokker F60 was officially the Model 0604. It was originally civil-certified under DGAC Type Certificate T-050-87. Upon the creation of EASA, this became EASA TCDS EASA.A.036. In addition, the F60 was military-certified in the Netherlands under KLu TCDS Number 4.

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by dlednicer
Sat Apr 04, 2020 6:22 am
Forum: Technical/Operations
Topic: A320 antenna locations
Replies: 9
Views: 2623

Re: A320 antenna locations

2 is the LiveTV satcom dome containing a TV downlink antenna. These have now all been replaced on the JetBlue aircraft with the FlyFi domes that cover the TV downlink antenna and broadband uplink/downlink antenna. Also, you don't have them marked, but there are two ADF antennas ahead of the satcom d...

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by dlednicer
Thu Nov 21, 2019 1:37 am
Forum: Technical/Operations
Topic: L1011 Question About a Small Detail
Replies: 31
Views: 4534

Re: L1011 Question About a Small Detail

When you have a protrusion sticking straight up out of a surface over which air flows, an interference vortex called a "horseshoe vortex" will form around the base of that protrusion. http://3.bp.blogspot.com/-YXJa6cxzjj8/Ty1w7vk5EII/AAAAAAAACb0/lINS1vmhfUQ/s1600/Horseshoe-vortex.jpg The ...

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by dlednicer
Mon Jul 29, 2019 8:28 pm
Forum: Military Aviation & Space Flight
Topic: The C5 nosewheel
Replies: 28
Views: 6276

Re: The C5 nosewheel

I bought a copy of the SAE paper. It indicates that the nose gear just rotates as a unit. However, the aft main gear bogies also steer, at 1/3 of the nose gear angle.

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by dlednicer
Tue Jul 23, 2019 5:49 pm
Forum: Technical/Operations
Topic: Solar batteries on airliner skin
Replies: 27
Views: 3306

Re: Solar batteries on airliner skin

The fuselage skin has to be accessible for periodic inspections. Every time someone does a skin inspection, they would have to peel them off.

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by dlednicer
Sat Jun 08, 2019 11:48 pm
Forum: Technical/Operations
Topic: On Flight Internet System / Turboprop
Replies: 6
Views: 2196

Re: On Flight Internet System / Turboprop

I’m not sure about what providers there are. However, it should work, as there’s still internet on jets at low altitude. Also, can a Q400 for example be retrofitted with a receiver by cutting a hole in the top of the fuselage to mount the receiver? Air-to-satellite (ATS) systems are not installed b...

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by dlednicer
Sun Feb 24, 2019 11:35 pm
Forum: Technical/Operations
Topic: Identifying Aircraft with Hushkit Installed
Replies: 9
Views: 1944

Re: Identifying Aircraft with Hushkit Installed

There were at least three 707 hushkit types: 1. Long-duct nacelle (N88ZL) 2. Comtran v1 with longer bypass duct, original intake (N707JT, VH-XBA) 3. Comtran v2: longer intake and bypass duct (on many 320C versions in the 90s) N88ZL has the Burbank Aeronautical/Quiet Skies hush kit for the 707. On t...

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by dlednicer
Sun Feb 24, 2019 11:15 pm
Forum: Technical/Operations
Topic: Evolution in airliners' nose shape
Replies: 10
Views: 2906

Re: Evolution in airliners' nose shape

Boeing engineers laid out the rationale for the design of the 787 nose in AIAA paper 2005-0422 "Optimizing Flight Deck Noise". The started with the knowledge that minimizing the flow velocity over the cockpit windows reduces cockpit noise. Then, they shaped the nose accordingly, to both re...

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by dlednicer
Mon Dec 31, 2018 9:59 pm
Forum: Technical/Operations
Topic: Air Pressure Adjacent to Fuselage Side and Tail Cone
Replies: 11
Views: 2788

Re: Air Pressure Adjacent to Fuselage Side and Tail Cone

As 747Whale said, its very complicated. The fuselage nose shape causes the flow to accelerate, but then it slows down aft of this. Over the wing, the flow is accelerated again, and then slows down again. Here are CFD pictures of the calculated pressure distribution on a 737-700 at cruise conditions....

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by dlednicer
Sun Nov 18, 2018 10:46 pm
Forum: Technical/Operations
Topic: Cessna Caravan 208B CAD
Replies: 1
Views: 2485

Re: Cessna Caravan 208B CAD

You are looking for a valuable commodity. I paid to have a CAD model of the outside surfaces of a 208B built from a laser scan and it cost $30k. Models of the internal structure are even more expensive to acquire. We scanned all of the internal structure of a GIV wing (using a wing from a scrapped a...

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by dlednicer
Tue Oct 09, 2018 2:31 am
Forum: Military Aviation & Space Flight
Topic: Imperial Iranian Air Force, pre revolution
Replies: 19
Views: 5488

Re: Imperial Iranian Air Force, pre revolution

747-2J9F cn 21668/ln 400 was being built for the IIAF when the revolution happened. It was stored, mostly-completed at Paine Field (I saw it there in 1983). In 1986 it was modified to a civil configuration and sold to Northwest Airlines. A friend of mine, who has flown it, tells me that it had an od...

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by dlednicer
Tue Sep 18, 2018 4:11 am
Forum: Technical/Operations
Topic: Engine over the fuselage question
Replies: 38
Views: 3554

Re: Engine over the fuselage question

> The Hondajet is an example of over the wing. No other business jet does this. The Scaled Composites Triumph also had an over-the-wing engine installation. It was also the first airplane to fly with FJ44 engines. I did the aero design of the nacelle installation and will say that it wasn't easy. 17...

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by dlednicer
Tue Sep 18, 2018 4:05 am
Forum: Technical/Operations
Topic: 732 Engine Addition
Replies: 12
Views: 1941

Re: 732 Engine Addition

Those are the original Nordam hushkits. As they added a drag decrement, a completely internal mixer hushkit was later developed.

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by dlednicer
Sat Aug 11, 2018 4:09 am
Forum: Technical/Operations
Topic: Clmax prediction at high cruise Mach (are you geek enough?)
Replies: 6
Views: 1156

Re: Clmax prediction at high cruise Mach (are you geek enough?)

Get a copy of Fred Obert's book "Aerodynamic Design of Transport Aircraft"

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by dlednicer
Fri Feb 23, 2018 5:26 am
Forum: Military Aviation & Space Flight
Topic: SpaceX - Tests, Launches, Developments
Replies: 2083
Views: 306447

Re: SpaceX - Tests, Launches, Developments

I'm joining this conversation rather late, so I apologize if someone has already commented on this. It was not commented on much, but this morning's launch out of Vandenberg AFB, besides carrying the Spanish Paz satellite, also carried SpaceX's Microsat-2a and Microsat-2b prototypes. The plan is to ...

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by dlednicer
Fri Feb 23, 2018 5:05 am
Forum: Technical/Operations
Topic: 747-200 wing vs -300 wing
Replies: 12
Views: 2468

Re: 747-200 wing vs -300 wing

The 747-200 and -300 wings have common OMLs. This is some information that Boeing published in an AIAA technical paper; It shows that the extended upper hump of the 747-300 and 747-400 improves the transonic area ruling of the aircraft. This increases the drag divergence Mach number of the aircraft....

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by dlednicer
Sun Feb 11, 2018 6:08 am
Forum: Technical/Operations
Topic: 737 MAX differences
Replies: 10
Views: 3089

Re: 737 MAX differences

APU inlet and exhaust are visually different. Split winglets. Engines of course. Many have a SATCOM dome on top. Most of the SATCOM atenna thee days are flush mounted.An example would be the BALL SATCOM on Trumps 757 which is slightly aft of the 1L and 2L doors, Hard to see, but its there. I think ...

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by dlednicer
Sat Jan 20, 2018 9:31 pm
Forum: Technical/Operations
Topic: Just what is involved to kit out aircraft with WiFi?
Replies: 10
Views: 1606

Re: Just what is involved to kit out aircraft with WiFi?

https://vimeo.com/70133676
https://www.youtube.com/watch?v=2WMuxEJraPc
-->

Here is what is involved:
https://vimeo.com/70133676
https://www.youtube.com/watch?v=2WMuxEJraPc

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by dlednicer
Sun Dec 03, 2017 3:39 am
Forum: Military Aviation & Space Flight
Topic: B-52's In Vietnam, How Many Were Lost
Replies: 25
Views: 61421

Re: B-52's In Vietnam, How Many Were Lost

I've been to the B-52 Victory Museum and the nearby Hồ Bảy Gian. Here is a picture of the wreckage in the lake

Image

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by dlednicer
Sun Oct 15, 2017 6:30 am
Forum: Technical/Operations
Topic: Airfoils horizontal and vertical stabilizers DC-4 C-54
Replies: 2
Views: 1095

Re: Airfoils horizontal and vertical stabilizers DC-4 C-54

Or contact me here!

I am pretty sure that they were designed with NACA 0012 airfoils.

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by dlednicer
Sun Oct 08, 2017 8:29 pm
Forum: Technical/Operations
Topic: Internet in Flight / KA vs KU Band
Replies: 4
Views: 1707

Re: Internet in Flight / KA vs KU Band

Ka can provide higher individual bandwidth, but is vulnerable to atmospheric moisture. Right now, there is more total Ku bandwidth available than Ka, but this will change. Connectivity (satellite) providers are: Intelsat Ku and Ka Eutelsat Ku and Ka Hughes Ku and Ka SES Ku Inmarsat Ka Viasat Ka Tele...

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by dlednicer
Sun Sep 03, 2017 11:27 pm
Forum: Technical/Operations
Topic: WiFi Fuselage Top Casing- Fuel Penalty?
Replies: 15
Views: 3650

Re: WiFi Fuselage Top Casing- Fuel Penalty?

I believe the location of the blister is defined by where it can ideally benefit from Area Rule. If there is a location along the roof where there's an optimum place then that's where it goes, where the dimensions of the body are such that adding the blister does the most good for this. No. There i...

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by dlednicer
Sat Jul 22, 2017 12:56 am
Forum: Technical/Operations
Topic: High Altitude Sickness v Cabin Altitude
Replies: 10
Views: 1377

Re: High Altitude Sickness v Cabin Altitude

I used to get altitude sickness on airliners. Now, I drink coffee before and on a flight and don't have the problem. Thanks to the drug Diomox, I have spent extensive time on the ground at high altitudes (above 8,000 feet), without many problems. On one trip, we spent a week at 12,000 feet and above...

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by dlednicer
Wed May 24, 2017 11:03 pm
Forum: Technical/Operations
Topic: 737-8 MAX Vmo
Replies: 1
Views: 1014

737-8 MAX Vmo

The Vmo/Mmo of the 737-8 MAX is listed on the Revision 58 of the A16WE Type Certificate Data Sheet as "VMO/MMO - 270 KCAS/0.82M for extension, 320 KCAS for extended, 235 KCAS for retraction of gear)." Does anyone know: is the Vmo/Mmo for the MAX truly 270/.82? Or, are these gear extension ...

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by dlednicer
Sun Mar 26, 2017 5:09 pm
Forum: Technical/Operations
Topic: Lift to Drag ratios at Take-off, Cruise and Landing for A320
Replies: 16
Views: 6262

Re: Lift to Drag ratios at Take-off, Cruise and Landing for A320

There is a whole chapter on this in Fred Obert's book "Aerodynamic Design of Transport Aircraft"

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by dlednicer
Tue Mar 07, 2017 6:44 am
Forum: Technical/Operations
Topic: DC-9 "Emergency Escape Chute" Deployment? Thoughts?
Replies: 4
Views: 1794

Re: DC-9 "Emergency Escape Chute" Deployment? Thoughts?

As flight testing involves much higher risk than normal operations, emergency egress is provided for the crew. This has been used several times. In the deep stall accident during flight testing of the Canadair CL600 Challenger on April 3rd 1980, two of the three crew members were able to bailout via...

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by dlednicer
Tue Mar 07, 2017 6:32 am
Forum: Technical/Operations
Topic: Aircraft Type Certification
Replies: 9
Views: 1828

Re: Aircraft Type Certification

The type cert covers pretty much the entire plane. Any major mods require a STC. An example is the hush kit mods that were done on the 727. Some changed the engine nacelles and thrust reverser configs which required an STC for all the changes. Another version changed the number 1 and 3 motors to a ...

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by dlednicer
Sat Feb 18, 2017 10:56 pm
Forum: Technical/Operations
Topic: How are differently placed tail rotors able to counter Angular Momentum?
Replies: 8
Views: 1540

Re: How are differently placed tail rotors able to counter Angular Momentum?

Research has shown that the optimal tail rotor configuration is a "pusher" tail rotor with the rotation set up with the bottom blade advancing in the forward direction. This results in the blade slicing up through the main rotor wake. The rotation direction is very important and resulted i...

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by dlednicer
Sat Sep 10, 2016 11:33 pm
Forum: Civil Aviation
Topic: True Max Speed Of 747/VC25
Replies: 21
Views: 7751

Re: True Max Speed Of 747/VC25

According to the FAA Type Certificate Data Sheet, Mmo of the 747-200 is M=0.92. As it is an older, pre-amendment 25-91 airframe, you can figure that Mdive is 0.05 greater (M=.97).

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by dlednicer
Sat May 28, 2016 5:29 pm
Forum: Technical/Operations
Topic: WiFi Antenna Fuel Burn Penalty?
Replies: 26
Views: 8984

RE: WiFi Antenna Fuel Burn Penalty?

The fuel burn penalty for installing a satcom radome on an airliner is usually less than 1%. The actual value depends on which radome, which airplane its installed on and where it is installed on that airplane.

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by dlednicer
Sun May 15, 2016 6:28 pm
Forum: Technical/Operations
Topic: Boeing 707 With "tail-mounted Engine? It Existed!
Replies: 11
Views: 6087

RE: Boeing 707 With "tail-mounted Engine? It Existed!

There were two 5-engine Boeing 299Zs built - one for Pratt & Whitney and one for Curtiss Wright. The P&W example was later "Liberty Belle", which burned out after a crash landing in 2011. The <acronym title="Air Marshall Islands">CW</acronym> example later became a water bomber and was lost ...

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by dlednicer
Thu May 05, 2016 1:27 am
Forum: Technical/Operations
Topic: What Purpose Does This Frontal Fin Serve On MD-88?
Replies: 36
Views: 10949

RE: What Purpose Does This Frontal Fin Serve On MD-88?

Here is the explanation for the strakes, straight from the authoritative source: AIAA paper 85-4067 "Aerodynamic Bugs: Can CFD Spray Them Away?" R. S. Shevell, Stanford University (formerly chief of aero at Douglas Aircraft) DC-9-50 and <acronym title="Air Madagascar">MD</acronym>-80 Fliselage Strak...

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by dlednicer
Sun Dec 13, 2015 8:13 pm
Forum: Aviation Photography
Topic: Spotting And Photography At Kahului (OGG/PHOG)?
Replies: 4
Views: 5212

RE: Spotting And Photography At Kahului (OGG/PHOG)?

Be careful spotting at <acronym title="Kahului (OGG / PHOG), USA - Hawaii">OGG</acronym>. Airports in Hawaii are generally not spotter-friendly. I've been hassled at all of them. I think some of it is the animosity locals have for haoles. I've had several workers give me the typical line that "photo...

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by dlednicer
Mon Oct 26, 2015 5:09 am
Forum: Technical/Operations
Topic: JetBlue Sat. Tv And FlyFi Coverage
Replies: 7
Views: 3175

RE: JetBlue Sat. Tv And FlyFi Coverage

<table border="0" align="CENTER" width="95%" class="quote"><tr><td><font size="2" face="ARIAL, Helvetica, Geneva" color="#9A9DA0">Quoting <a href="/profile/ChaosTheory" class="quote" target="_blank">ChaosTheory</a> (<a href="#5" class="quote">Reply 5</a>):<br/><i>nterestingly, <acronym title="JetBlu...

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