As a side note, since the primary drag discussion is still around the fins, I feel the base drag is being forgotten.
I’m trying to aquire a book regarding base drag, as its not as simple as other types of drag, but if we take base bleed shells as an estimate, they are said to have an increase in range anywhere between 20-50% over non-basebleed counterparts, and base bleed shells produce no thrust.
As I can’t figure out how long the small gas generator on the back of a basebleed shell lasts, there could be a whole slew of scenarios we could assume from that;
- Basebleed gas lasts until target (20-50% range increase, 2 tests to get an approximate range)
- Basebleed gas lasts until for an unspecified period of the flight(20-50% range increase, 2 tests to get an approximate range)
- 50% range increase obtained from basebleed lasting until target while 20% is from basebleed gas lasting an unspecified amount of the total flight time (reduce drag by 50% during motor burn. I dont like this theory since a shells drag is something like 60% from the air against the shells nose/body, so it doesnt really make sense, but could be tested)
Another assumption that could be used would just be by compairing how much the AIM-7F’s motor overperforms, since we know the AIM-7-E2 is performing according to documentation and both have the same drag.
7F boost stage (4.5 sec) overperforms by ~5.3%
Post boost weight is too high by 13.9%
7F sustain stage (11 sec) overperforms by a whopping ~40%
Post sustain weight is too high by 25%
7F booster burns for 1.7 sec more than the E-2
7F sustainer burns for 11 seconds more than the E-2
Now, I’m sure I could sit down and try to figure out the calculation to figure out the absolute fuckery that is the gaijin AIM-7F to determine an approximate impact of base drag, but even then, it may not help us 100% since base drag is also dependent on shape of the base, shape and size of the fins, speed, etc…
I dont really feel like doing it, but its my input on base drag until I either decide to actually make a CFD for the missiles, or get my hands on papers regarding the impact of thrust on base drag and actually decide to slog through it for an internet argument to try to disprove one specific guy that will likely still find some stupid way to spin the info he gets from reading tea leaves to determine that hes right all along and every air to air missile developper, and every official piece of documentation on the R-77 thats publicly available is wrong.
Now that I’ve thought it over, im definitly not going to put that effort in because he’ll just dream up some other source or draw something on a napkin with some google translate russian writting and use that as his next source to “prove” the R-77 range is over 100km