Author Topic: F-4 air intakes  (Read 1879 times)

Offline Geoff

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F-4 air intakes
« on: February 16, 2016, 05:22:40 PM »
Ok this may be a bit of a daft question but -

The UKs F-4K and M had 20% bigger air intakes for the Speys. The splitter plate looks to be the same on both US and UK models.
1, Am I right in thinking this is because of the boundary layer of air from the fuselage in front of the intake?
2, If you changed the nose significantly the splitter plates would change???  I am thinking of a longer radome and different engines, 2 Lyulka Al-21s, but I am unsure about dimensions, if too wide then a reverse engineered J-79. Yes I know this has been done before I am not an original thinker I'm afraid :-[
I have checked the physical dimensions and they are close enough for my purposes. O0

I hope this makes sense.
« Last Edit: February 16, 2016, 05:32:35 PM by Geoff »

Offline kerick

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Re: F-4 air intakes
« Reply #1 on: February 17, 2016, 01:40:14 AM »
I don't believe the splitter plate would change as it is meant to control the airflow before it gets to the engine. I think it would have to be a radical change in the nose shape or quantity of air going to the engine to require a change.

Offline Geoff

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Re: F-4 air intakes
« Reply #2 on: February 17, 2016, 02:19:02 AM »
Thanks - that's what I needed to know. So my Su-19 will have "normal" F-4 intakes and splitter plates (or something similar) ;D

Offline elmayerle

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Re: F-4 air intakes
« Reply #3 on: February 17, 2016, 02:39:09 AM »
In as much as the intakes on the F-4K and F-4M were wider, not taller, there's no reason the splitter plates should change as the airflow in that area stays the same, as does the basic structure.  A quick check shows that the Al-21 matches the diameter of the version of the Spey used in the F-4K/M and you could probably use those intakes without a problem.  A small spacer between the top and bottom of the intakes and the fuselage would allow you to adapt standard F-4 intakes to the higher mass flow requirement.

Offline Geoff

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Re: F-4 air intakes
« Reply #4 on: February 17, 2016, 06:48:00 AM »
Thank you.

Offline kerick

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Re: F-4 air intakes
« Reply #5 on: February 17, 2016, 08:44:47 AM »
This sounds interesting, keep us posted.

Offline GTX_Admin

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Re: F-4 air intakes
« Reply #6 on: February 20, 2016, 12:12:20 PM »
Al-21s...hmmmm...something akin to this planned perhaps?

.
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Offline Geoff

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Re: F-4 air intakes
« Reply #7 on: February 22, 2016, 01:41:50 AM »
Yes I have an F-4M on the blocks as a Chinese built Phantom with Speys.
The Soviet one is a re-do of an earlier Wif I did that got modified when it fell and landed under it's base.
It was based on an F-4E, from an idea I saw on a website
It had much smaller splitter plates to give the optical illusion that the nose was longer. Plus F-4C exhausts, A 23mm twin barrel cannon under the nose -etc.
I did not put the under nose fairing on so was wondering if I could get away with making the splitter plates smaller. I suspect it would not work in reality of course - but it's my toy plane!

The back story is that after Nixon's visit to China in '79 although there was some thought of selling the F-16A-79 (another one in line for building). The US sell a small batch of Phantoms, as in F-4J/S which have been fitted with Chinese radios and weapons etc plus a plan to licence build them with Spey engines they already make. The UK using Spey powered F-4s help the PRC with the manufacture along with McD/D. This being the start of a long standing raprochment with the PRC and in an alliance against Reagan's "Evil Empire" USSR.
OK unrealistic I know but it gives me a half way plausible reason to have a PLANAF F-4.

The Soviet version was a reverse engineered project in place of the Mig-23/27  and Su-17/20 series of aircraft. Due to problems with wing pivots (think F-111A with a vengeance). So Korean and Iranian planes are obtained and form the basis of a small production run. (Yes it will not work I know - time scales all over the place). By the time the F-4ski is entering service the problems with the Migs and Sus are sorted. The Su-19 is operated by the IA-PVO mainly in the southern and eastern republics. It was found to be a good bomb truck so a number of Frontal Aviation Regements also converted to this type. Interestingly the Su-19B (Bombardirovski) had a laser designator in an undernose fairing very similar to a shortened F-4E's nose.

Forgive my "Russian" I only know a few words and half of them are rude! O0
« Last Edit: February 22, 2016, 02:00:33 AM by Geoff »

Offline GTX_Admin

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Re: F-4 air intakes
« Reply #8 on: February 22, 2016, 04:14:51 AM »
Here's a Chinese Phantom story I whipped up nearly 10yrs ago:

"In 1973, the Chinese Ministry of Aeronautics (MoA) began the theoretical evaluation on a next-generation supersonic tactical bomber aircraft intended to replace both the H-5 (IL-28 Beagle) light bomber and the Q-5 (Fantan) attacker in the PLA service.

The development task was assigned to 603 Aircraft Design Institute based in Xi’an, Shaanxi Province. A research team was set up in early 1974 and team members were sent to the PLA Air Force (PLAAF) and PLA Navy (PLAN) to discuss the requirements for the new bomber.

After studying the specifications submitted by the PLAAF and PLAN, the MoA and 603 Institute concluded that it was possible to develop a single airframe with different weapon and avionics configurations to fulfil the requirements of both services, thus saving the development expenses and time. In February 1977, the State Council and the Central Military Commission jointly authorised the new bomber development programme. The aircraft was initially designated Hong-7 (H-7) in line with the Chinese bomber designations.

However, like most defence projects in the early 1980s, the H-7 development was almost on frozen in 1980-1981 as the country’s economic development was given a higher priority.  However, the PLA still desperately needed a replacement for its ageing H-5 bomber.  Therefore, in 1982 the Chinese leadership directed that a simpler solution be put forward (preferably one based upon an existing, proven design).

With the United States of America and China experiencing what could best be described as a “honeymoon” in their relations, the possibility of China purchasing an American aircraft design was a distinct possibility (to help China modernise its forces against the Soviet Army, the U.S. had already offered its Sikorsky S-70C Black Hawk helicopter to the PLA). Initial speculation centred on a version of the F-16 or F/A-18, however, not wanting to repeat the debacle of Iran, the older F-4 Phantom II design was offered instead.

This was still a great step up in performance for the Chinese and more importantly was more in line with their manufacturing capabilities. Consequently, in late 1982 a deal was signed for the license production of 100 F-4 Phantoms by the Xi’an Aircraft Factory. In PLAAF/PLAN service, the aircraft was designated JianHong-8 (JH-8).

The JH-8 differed from the standard F-4 Phantom in being powered by the Chinese WS-9 turbofan. This was a license built Rolls Royce Spey and had already been selected as the power plant for the H-7. In this respect, the JH-8 is closer to the British FGR.1/2 Phantoms.

In 1982 work had also began to replace the unimpressive J-8 (Finback-A) type with a new design known as the J-8II. With the JH-8 deal already on the table, it was also decided to investigate a pure fighter version. Consequently, in 1983 it was decided to expand the terms of the license production agreement to include a further 160 fighter versions of the JH-8 as the J-8II.

JH-8s and J-8IIs serve with numerous PLAAF/PLAN units, but perhaps the most interesting are those operating from the PLAN’s only aircraft carrier, the “Zheng He”. This carries a total of 40 such aircraft operating in a mixed fleet."
All hail the God of Frustration!!!

Offline Geoff

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Re: F-4 air intakes
« Reply #9 on: February 22, 2016, 06:31:31 AM »
Works for me.  ;)

I like the J-8II designation - I think I will go with that too. Just reread it and it is very plausible. Also the French were selling them a lot of stuff around this time. I did do a PLAAF Mirage F-1 some time back. It's at the back of this pic.

The Soviet one was based on this model in the bottom pic.
« Last Edit: February 22, 2016, 06:11:48 PM by Geoff »