Posting about the MiG-23 and other aircraft.
Aerodynamics, Structures, Engines & Performance.
Apr 1 • 16 tweets • 4 min read
Su-15 Flagon turn rate🧵
There isn't that much online info available on this subject. Here's what I could find...
According to the Su-15UT manual (two sear trainer) with two Tumansky R11F2S-300 engines (6200 kgf each), 6030L of usable internal fuel volume (5005 kg at 0.83 kg/L, T1 grade fuel). By my estimates, total internal fuel volume is 6140L (5096 kg at 0.83 kg/L).
Nov 4, 2024 • 34 tweets • 12 min read
Convair B-58 Нustlеr🧵
The B-58 was the most technologically advanced aircraft of its time. A Mach 2, wasp-waisted war chariot, drawn by four J79s, including silver brazed stainless steel honeycomb panels in its design.
But before getting into the technical stuff, some context.
The XB-58/YB-58 (aircraft № 1, tail number 5660) first flew on November 11, 1956, made at the Convair plant in Fort Worth, Texas. At this stage, it was without a belly-pod, tail gun, and was equipped with the J79-1 instead of the J79-5.
Sep 30, 2024 • 60 tweets • 19 min read
Spike inlets, the TsAGI way.
Soviet vs. Western designs🧵
One of the most common design of air inlet used on supersonic aircraft is the axisymmetric diffuser with external compression (which is just a fancy way of describing the spike/cone inlets of the...
MiG-21, Su-7/9/11/17, Yak-28, Tu-128, F-104, B-58, F-111, the Mirage family, Lightning, Lavochkin La-250, Mikoyan & Gurevich SM-12/12PM/12PMU, Ye-3U, I-7, I-75, Ye-150/152, MiG-23PD, Sukhoi P1, T-37, Saunders-Roe SR.177, Bristol T.188, BAC TSR-2... I think that's all of them 😮💨.
Sep 6, 2024 • 11 tweets • 6 min read
MiG-23ML or MiG-23MLA?
A pedantic🧵
I see a lot of people use the term "MiG-23MLA" when referring to the MiG-23ML with Sapfir-23MLA/Sapfir-23MLAE radar.
To be fair, I've also noticed a lot of former Soviet pilots use this term in order to differentiate between the MiG-23ML...
...with Sapfir-23ML & MiG-23ML with Sapfir-23MLA. But I'm a snobbish MiG-23 fаnбоу, and as such, prefer to stick to nomenclature found in official documents.
First, some context. The MiG-23ML (product 23-12, product 3) with Sapfir-23MLA (product N003 or 323MLA) radar &...
Aug 29, 2024 • 5 tweets • 2 min read
MiG-23 pilot stories/comments🧵
Here, I'll gradually be posting various random MiG-23 themed stories, comments & opinions by pilots or maintenance people, collected by me.
MiG-23P "belly take-off".
Unknown author.
Aug 16, 2024 • 22 tweets • 8 min read
MiG-23 timeline🧵
The development of the MiG-23PD (aircraft 23-01) was decided in a goverment decree issued on 30 April, 1965. Its first flight was with P.M. Ostapenko at the controls, on 3 April, 1967.
Government approval for building the MiG-23 (23-11) aircraft with variable sweep wings, is issued to OKB-155 (MiG) on 28 February, 1966.
The first prototype, 23-11/1 (№ 231), with a R27F-300 engine, is transported for flight testing at Zhukovsky on May 26, 1967.
Aug 4, 2024 • 24 tweets • 7 min read
How fast is the MiG-23? 🧵
Probably the only thing the MiG-23 ever managed to impress with was its speed and acceleration, with the wings swept back the 72° position.
Almost every source you can read will tell you that its maximum Mach at high altitude is 2.35... which it is, but only due to a degradation in directional stability and limitations in cockpit canopy material strength. Its true, thrust limited, maximum Mach is quite a bit higher.
Jul 30, 2024 • 19 tweets • 6 min read
Tumansky R11F-300 vs. General Electric J79 - worlds apart. 🧵
The MiG-21 & F-4 have very different layouts, & their engines are no less dissimilar. Although both engines seem alike, the R11 and J79 were designed with different priorities in mind.
The mid 1950s is, for me, one of the most interesting periods in jet engine design. Every desig team was using its own distinct solution of increasing compressor pressure ratio (PR).
Jun 30, 2024 • 4 tweets • 2 min read
MiG-23MS, the worst MiG-23?🧵
Today I'm going to NOT complain about how crappy the MiG-23MS was. Instead, I'm going to tell you two things which it did better than the MiG-23M & MiG-23MF.
1 - Internal fuel capacity.
The MiG-23MS had the largest internal fuel capacity of any MiG-23 fighter variant. Since it didn't have the heavy and voluminous Sapfir-23D-III radar of the MiG-23M, a part of the avionics bay behind the cockpit could be used for more fuel.
Jun 21, 2024 • 12 tweets • 3 min read
Tumansky vs. Eurojet. Short 🧵
To understand how jet engine technology has evolved from the late 50s up to the late 90s, it's useful to compare engines of similar architectures. A pair that fits this criterion is the Tumansky R13-300 (or R25-300) & the Eurojet EJ200.
Why are these engines a useful to compare? As said, because of their similar architecture.
Both have:
- twin-spool (or dual rotor) design,
- 8 compressor stages (3 Low pressure (fan in the case of EJ200) + 5 High pressure), 2 turbine stages (1 LP + 1 HP),
While the MiG-23 was going through state evaluations, the movable wing's design was changed, increasing the chord by 10% in order to incorporate a dog-tooth. This also increased the leading edge sweep angles by 2°40'.
Photo: igor113.livejournal
This also increased the leading edge sweep angles by 2°40', so for example 45° became 47°40'. The exact reasons for this change are rarely detailed in most books, but test pilot A. A. Shcherbakov mentions it in "Штопор на МиГ-23 - А.А. Щербаков, Авиация и Космонавтика, 2008":
Mar 30, 2024 • 21 tweets • 7 min read
A3J Vigilante - the gold plated, titanium giraffe🧵
The North American Aviation A3J (first flight 31 August 1958) was one of the most advanced aircraft of its time, especially in terms of manufacturing technologies.
Two that I am most interested in are the use of aluminium-lithium 2020 alloy and of titanium alloys.
For the titanium alloys topic, I recommend "Solving titanium fabrication and reliability problems in aircraft, by W. Stuart Lyman, C. T. Olofson, A. M. Federico · 1959".
Mar 25, 2024 • 30 tweets • 11 min read
Mirage F1 flight performance🧵
I like the Mirage F1. I like the most its wings that have automatic leading edge slats & tip mounted infrared missiles, its decent visibility over that long pointy nose, and the area ruled fuselage.
Unfortunately, it's difficult to find much info about its flight performance and manoeuvrability. What little info I have been able to find over the years, paints an unexpected picture.
Mar 21, 2024 • 21 tweets • 8 min read
MiG-21 area rule 🧵
The aerodynamic reason in change from the MiG-21F-13's spine shape to that of the MiG-21PF's is never thoroughly explained in any books on the Fishbed that I know of. That spine was used on MiG-21PFS, PFM & FL too.
Soviet MiG-21F-13 Indian MiG-21FL
The only online publication that I found to discuss this in enough detail is NASA-TM-84647 "Aerodynamic assessment of various supersonic fighter airplanes based on soviet design concepts - M. Leroy Spearman 1983”.
North Korean MiG-21F-13
Mar 13, 2024 • 12 tweets • 4 min read
MiG-23 structural problems 🧵
Part 1 - introduction
Early MiG-23s were deficient in many regards, avionics, weapons, flight characteristics and reliability being the main ones.
In a previous thread I presented the aerodynamic problems limiting the manoeuvrability of early MiG-23s. Those problems were made tolerable with the introduction of an AoA limiting device called SOUA (essentially a stick-pusher) and an aileron-rudder-interconnect called SAU-23.
Mar 1, 2024 • 15 tweets • 6 min read
Supersonic static directional stability - a short🧵
In a previous thread, I compared the small diameter MiG-21F-13 inlet with the larger diameter one of the MiG-21PF. The main conclusion was that the PF intake was likely disadvantageous in terms of additive drag at supersonic...
...speeds, and that it was a compromise design in order to fit the larger diameter radar antenna.
Well flight testing of the Ye-7/1 (the first MiG-21PF prototype) revealed one more drawback of the new inlet design, it's negative impact on static directional...
Ye-7/1
Feb 26, 2024 • 27 tweets • 8 min read
McDonnell F-4 Phantom II - The Flying Brick 🧵
When trying to read about the F-4 Phantom II, I come across the expressions like "the triumph of thrust over aerodynamics" or "even a brick can fly if you stick a big enough engine on it".
Even the president of the McDonnell Douglas aircraft company, George S. Graff mentions this at the minute mark 21:48!
Feb 10, 2024 • 45 tweets • 17 min read
MiG-23MLD manoeuvrability thread.
By most accounts from pilots that flew it, the MiG-23MLD, product 23-18 (МиГ-23МЛД, изделие 23-18) represented a noticeable improvement in maneuverability compared to MiG-23ML (изделие 23-12) and MiG-23P (изделие 23-14).
Bulgarian MiG-23ML.
This was achieved through means of:
- λ-extensions - vortex generators at the wing root,
- pitot-tube mounted vortex generators (PVD-VG),
- automatic drooping leading-edge flaps (DLE) coupled with a new wing sweep-angle of 33°.
East German MiG-23ML 23-12A
Feb 8, 2024 • 19 tweets • 9 min read
MiG-21 inlet design thread - MiG-21F-13 vs. MiG-21PF.
Note: I use inlet & intake interchangeably.
When redesigning the MiG-21 from the small nosed day fighter version, the MiG-21F-13, into the all-weather PF, to fit the radar in the nose, the inlet had to be completely redone. For a long time I wondered if the redesign was a compromise or an improvement in terms of...
Feb 3, 2024 • 40 tweets • 13 min read
MiG-23 air intakes design.
Whenever somebody brings up the MiG-23 intakes, there is always that person who just has to say "yeah, it's just a copy of the F-4 Phantom intakes, they even copied the number of boundary-layer bleed holes and those struts that are meant to cut the...
...arresting net to allow the canopies to open". And I, as any self respecting бutt-hurt MiG-23 fan-boy, will automatically deny it, while tears run down my cheeks.
In truth, the MiG-23's variable intake ramp system is indeed evidently based on that of the F-4's. Despite it...