Many thanks for the effort you have installed into these videos, my technical addictions satisfied manifold with every installment. (Particularly turbo pump part 2, worth the wait). Your attention to detail truly commendable.
I had no idea I wanted to deeply understand how a V2 worked, but it turns out I do. I remember building a V2 model rocket when I was like 12, had to be like 1981, and loved it.
I was fortunate enough to buy a second hand copy of a German book many years ago, about Peenemunde and the various fails during the design schedule for the V1 and V2 weapons, so this series is fascinating for me..thank you !!
Excellent. Those subtle changes of the valve are the essence of engineering... To achieve perfection a myriad of wee adjustments are necessary... Thanks!
Lots of Comprehensive & detailed Info here !! .....Some dry Ice shaft Chiller + Focused torch flame or Spot induction Heat applied to Nut would likely have easily broken Loose the Nut threads.....
Another great video. I would love someone to see someone make a model of this and film it with inert fuel in slow motion. Or even do a good computer animation of the flow and mixing
Fantastic series, love it. Eventually of course, we are going to get to the point where the only thing left to do is to crowd source the funds necessary to re-manufacture all the parts and fly one. Well that's probably ridiculous to suggest we fly one. To fly two or three would be much better.
Hi Alex, and thanks for posting. Well, some Canadians have already tried it, over twenty years ago. The ill-fated Canadian Arrow used pressurised tanks rather than turbopumps, but otherwise, they copied the V2 engine pretty faithfully. Though quite why they did something so oddly anachronistic is a different matter. Walter Thiel, Peenemünde's chief combustion expert, declared shortly before he died in 1943 that they would never build a rocket engine like the A4 power plant again and regretted many of the missteps that took them to the necessity of flying the 18-prechamber engine. So quite why the Arrow team thought it was still a good idea just two decades ago escapes me. KR RJD A&NTV
Marvelous video as always! So I would like to make three related comments. 1) I think it makes sense that the ball valve would be a pilot valve for starting the reaction at a lower flow rate to heat up the reactor, and prevent an explosive ignition, like can happen in rocket engines on ignition. I also wonder if the ball valve might not be a flow regulator during the burn, because the hydrogen peroxide and permanganate gas pressure must reduce overtime, but you would not necessarily want to reduce steam production to the turbines until you are ready to shut off the engine. The flow rate might have been kept up even with lower gas pressure by the opening of the ball valve. 2) since you have a pristine working model of the valve complex, and you also have the drawings, you should be able to measure the spring constant of the springs and then model the entire valve assembly in a suitable hydraulic simulator, which of course the Germans would’ve died for a 1940, but we have those today. 3) taking that one step further, since you do have a pristine valve assembly, why not just test it with high pressure water and suitable instrumentation and just see what it does? That would resolve the debate pretty much once, and for all I should think. Thanks for all you do!
very interesting! about the 8 ton and 25 ton valves, how i interpret the physics; the 8 ton valve opens before the 25 ton valve, at somewhat lower pressure, and also the reaction of H2O2 with the permanganate in the cup near the splash plate, invigorates the turbulence and reactivity of the permanganate, improving mixing and reaction with the H2O2 of the 25 ton valve, and reaction in the rest steam chamber. a kind of two stage reactor, of which the "first stage" is fed by the 8 ton injector. the kegel valve does the same thing as the ball valve in the 8 ton valve. less good probably (or some reason they changed it).
The technology behind these parts is fascinating-- I have always found the turbopumps to be the most interesting parts of a rocket, and I am also an old steam hand-- but, of course, the history behind the A4/V2 includes tens of thousands of slave laborers worked to death at Dora Mittelbau and elsewhere. Were these sub-assemblies built by slave labor?
So my analysis of the subvalve is that it must open before the main valve and close after the main valve. That is, any time that the main valve is open, the subvalve is also open. The main valve is opened by a pressure difference. The pressure on the upstream side of the valve must exceed that on the downstream side by enough to to produce a force which overcome the spring pressure, and this pressure difference must be maintained to keep the valve open. Once the valve lifts from its seat, the pressure does not equalize, because this would destroy the pressure difference which is holding the valve open, and the valve would close. Rather, the annular gap between the valve and the seat acts as an orifice which has a pressure difference across it. The more the valve opens, the larger the orifice and thus the less the pressure difference across the valve and the less force there is available to hold the valve open. This system will naturally reach an equilibrium in which the orifice created is just wide enough that it maintains the amount of pressure upstream necessary to hold the valve open. Because the pressure difference across the main valve does not equalize, the subvalve will still be held open even once the main valve opens.
I love this "Touching Actual History" - part of an actual V2 rocket - maybe have been launched and crashed- exquisite !! - thank you ! . Pit me on the mailing list for any "spare" V2 parts ;)
A Walter H2O2 engine was also developed for U-boats late in WW2 ! Correction: the Walter U-boat engine was developed before 1942, and before the aircraft and rocket engines. Source: Cremer, U-Boat Commander, 1982, English translation, 1984, p. 192. Wikipedia says Walter patented the design already in 1925.
If the h2o2 is pumped into the main valve at around 450psi and the reaction is creating steam at around 400psi, then the valve is going to be forced closed due to the spring pressure and valve surface area ratios etc. The smaller pilot valve could be a way of keeping the reaction stable by constantly allowing h2o2 to flow rather than having an oscillation of the main valve as it bounces open and closed causing the steam to pulse?
Hi there, and thanks for a good observation. Even if the psi pressure on both sides of the valve was more or less equal, the force (not the same as pressure) acting on the narrow aperture of the valve is lower than the force of the propellent entering the reactor chamber (pot) through the valve. And the chamber is not sealed, it vents directly to the atmos, so there will be a pressure drop along the mass flow as well. But I think there might have been vasilation in the pilot valve as you suggest. KR RJD A&NTV
I would be interested to know if the sub valve ball was lapped against its sealing surface. Also was there any specialized heat treating done on the ball valves and seats?
Hello Dennis, and any thanks for supporting my work - I appreciate your contribution. Every donation like this allows me to go on producing high-quality content on a subject that I'm passionate about, and there is a lot more to say. Best wishes Robert J Dalby
I am not sure, but until someone who can confirm this writes here, this is what i found about sodium permanganate "Being about 15 times more soluble than KMnO4, sodium permanganate finds some applications where very high concentrations of MnO4− are sought."
Since the alcohol component in the main fuel system allredy where dissolved in water i don't think water would interfer with any other part of the engines reaction, and by using sodium permanganate instead of potassium permanganate they could still manage to keep the concentration very high. Just my 5 cents...
Hi Maurice, and thanks for posting. The sodium permanganate was introduced into the reactor pot as a 27% viscous solution (kept warm before tanking in cold weather). It was pumped from the 11 litre storage tank and into the reactor pot by air pressure at about 400psi (30atm). A contact valve was used to ensure the permanganate arrived in the reactor pot before the high-strength (82%) hydrogen peroxide. Other permanganate reactants were also used (eg calcium) but NaMno4 was the norm. KR RJD
Given the change from machined cone to ball, I suspect the sub valve's initial purpose was found to be unnecessary , so simplified to just heating the chamber. To me, it's utility is to relieve the pressure in the pipe post 8/20ton valves (handy while testing)
Hi Bill, and thanks for posting. Yes, I think you may be right, and there was just enough in favour of the pilot valve rather than against it. I noticed how weak the spring was in the specimen examined, and it surprised me rather. I think the ball position would have fluctuated due to engine vibration - but presumably, by then, it didn't matter. KR RJD A&NTV
Hello. Many thanks for supporting my work - I appreciate your contribution. Every donation like this allows me to go on producing high-quality content on a subject that I'm passionate about, and there is a lot more to say. Best wishes Robert J Dalby
Most of the problems come from fast changes of pressure. Subvalve is there to even out hydraulic shock to the system. Aka water hamer which can destroy welds or even burst piping in this case it can lead to bad combustion in rocket engine chamber. Cold start or fluded chamber whit later ignition of accumulated fuel oxidiser mix is not recomended. Booom...
I don't think the lower spring support was fastened to anything. There was no need to fasten it. I work in a valve repair shop and I've seen the effects of a relief valve spindle that had repeatedly, at high frequency and force, pounded against its guide due to valve chatter and the metal on the surface of the relief valve guide looks exactly like the part in the steam pot valve. Kind of fractured looking.
I really love these video's. But seeing you force open that flanged connection in the beginning made me worried. Asbestos gaskets could have been used there. Please be careful, you guys.
Is there a reason you're sandblasting and not using electrolysis here? You'd preserve all of the base metal and be left with a perfectly rust free surface.
Hi there, yes, I've used electrolytic rust removal. It works as well as acid, which I've used extensively on stage one rust. Stage one is the surface rust we see on items only exposed to air for a decade or so. When late stage two rusting and decay, sets in on things that have been exposed to the elements or have been in the ground for eighty years, electrolysis can do little to restore the original surface because it simply doesn't exist anymore. I've only ever used a professional electrolysis service offered by a powder coater, so I have no DIY experience. But I have a sand-blasting cabinet and use this largley "because it's there" and is low-cost. I favour it because you can use materials other than grit and get a fine, almost polished surface on some items. Thanks for posting. KR RJD A&NTV
loved the engineering detail The waste of human effort engineering etc on weapons and indeed single use launch vehicles generally appalls me hence my adoration of reusable orbital rockets if not the recent politics of the instigator
18:04 thats really interesting.... definitely going to have to watch part 1 and 2 now lol . pretty modern design really..... after all the Saturn 5 was designed by an old nazi lol
