HVAR recoil

[Yo-Yo]

Yes, the firing of those rockets at 69 seconds+ is definitely rocking the truck. If you look at 25 seconds you see another truck firing a different type of rocket and the truck is not moving at all.

 

The rockets being fired at 69 sec seem to be much larger and are being fired from tubes.

 

The rockets being fired at 25 secs may be smaller and appear to be being fired from a rack, similar to how the HVAR are carried and fired.

 

Both trucks appear to be about the same size.

 

From this I would speculate that:

1. the fact that the rockets are being firing from tubes is exacerbating the reaction of the truck.

2. the change in weight of the payload of the truck suddenly changing is also causing the truck to be jostled.

 

From the size of the rockets at 69 secs I would also speculate that they weight far more than an HVAR. They definitely have a much larger diameter than an HVAR. The truck probably weighs only about 1/10 of what the P-51D weights.

 

I believe that viewing and comparing both sections of this video only strengthen my arguments :music_whistling:

 

HVAR - 127 mm and 61 kg... it's not a small rocket...

[Captain Orso]

It could be instead that the exhaust doesn't directly hit the wing, but causes flow to accelerate under the wing causing a loss of lift. It could even be a combination of both that results in less lift loss/gain than expected.

 

If the wing is effected, it probably gains a less ideal spanwise lift distribution which would increase the drag on the firing wing, which could lead to something like recoil.

 

The pressure in the exhaust jet will be much greater, not less, so there should be no loss of lift. Once the exhaust gases starts to slow and dissipate they will expand outward increasing their diameter.

 

Were that to affect the lift of the wing, then only far after the rocket were fired if the wing were to move through the exhaust gases. But I have my doubts about whether that actually occurs. The affect would at any rate be while the wing is moving through the rocket's exhaust and not directly upon firing.

 

My personal reaction is to say that DCS is overdoing the recoil, if it exists, but I wouldn't rule it out w2ithout a direct test. Jumping into a P-51 and firing HVAR's is probably out of the question, but I wonder if there would be merit to simulating a HVAR launch in great detail.

 

The merit would definitely be in the realism and at any rate not frustrating/confusing players/virtual pilots not being able to recognize the actions of the sim in the actual manual :smilewink:.

[NineLine]

The merit would definitely be in the realism and at any rate not frustrating/confusing players/virtual pilots not being able to recognize the actions of the sim in the actual manual :smilewink:.

 

But players/virtual pilots also understand that the written word doesnt always cover everything, and it certainly cant change the laws of physics, otherwise I would make a manual and state I had super powers ;)

 

We should be aware of the statement from the manual, but it doesnt mean its the be all end all.

[Destroyer37]

That's surprising because most military airplane flight manuals are fairly accurate with this kind of thing, especially considering how much testing is done on the subjects contained in them. But what do I know...

[NineLine]

That's surprising because most military airplane flight manuals are fairly accurate with this kind of thing, especially considering how much testing is done on the subjects contained in them. But what do I know...

 

 

But what does 'fairly accurate' equate to? And are you talking modern manual or 1940 manuals? All I am saying is when you are trying to prove or disprove something, having more than one line of type is always better. There is nothing wrong with seeking more info from other sources if it exists.

[Captain Orso]

Small nitpick, but that truck is moving, not much but it is, the smoke masks it some, but you can see it better on the second shot... not a big deal, but figured I would mention it ;)

 

Also if it was mostly weight causing the rocking, wouldnt the truck rock opposite as the weight is transferred to the end of the tube, then released?

 

Honestly, I'm not seeing the truck at 25 secs moving at all, but if it is it's certainly not moving like the one at 69 secs.

 

I'm not going to even try to speculate on what all the affects of the rocking going into motion and moving through the launching tube might be. Friction would suggest that the firing tube be pulled along, but it has to overcome inertia to start moving and then it will not move linearly, because it is anchored to the bed of the truck. So the rocket starts out moving linear, while the tube, if it is being pulled, will start moving in a curve, which will cause even more friction as long as the rocket is in the tube.

 

At any rate, we can see that the launching tubes are recoiling/being pushed backward and this is probably from the exhaust gases pushing rearward through the tube; they definitely are blowing back through the tube.

 

After some more thought, removing the weight of the rocket from the truck will simply allow it to expand its suspension at the rate the shock absorbers will allow, so not very quickly and there should be minimal rocking caused by this.

 

Ergo, the 'recoil' is from the exhaust gases affecting the launching tube.

[Captain Orso]

HVAR - 127 mm and 61 kg... it's not a small rocket...

 

They're certainly nothing to sneeze at :D, but those rockets on the second truck appear to be about twice the diameter of an HVAR, which means 3x the mass along the same length, which appears to be about 4 feet generously comparing to the men standing next to them, assuming they are small, undernourished Libyans and stand only about 5 feet and a couple of inches :smilewink:

[Captain Orso]

But what does 'fairly accurate' equate to? And are you talking modern manual or 1940 manuals? All I am saying is when you are trying to prove or disprove something, having more than one line of type is always better. There is nothing wrong with seeking more info from other sources if it exists.

 

I agree. I'd rather know that the truth were vindicated and not the text.

[Yo-Yo]

That's surprising because most military airplane flight manuals are fairly accurate with this kind of thing, especially considering how much testing is done on the subjects contained in them. But what do I know...

 

THe P-51 manual claimed that with the dead engine the plane can fly 15 km from 1 km height. And it's a nonsense because either calculations regarding windmilling prop drag or real pilot's experience told about maximum 1:10 gliding rate with low rpm setting. So, have no illusions about ABSOLUTE accurate manuals.

[Holbeach]

OK, Sithspawn.

 

Your reply, is a pathetic internet thumbs down, red square, to add to my collection.

 

My argument is from, The Ordnance School Aberdeen Proving Ground Maryland, 1944.

 

What does it take ?

 

Let me know if you need any more.

 

 

..

[Destroyer37]

THe P-51 manual claimed that with the dead engine the plane can fly 15 km from 1 km height. And it's a nonsense because either calculations regarding windmilling prop drag or real pilot's experience told about maximum 1:10 gliding rate with low rpm setting. So, have no illusions about ABSOLUTE accurate manuals.

 

Have no illusions sir, I mentioned no absolutes. Keep in mind this IS aviation, nothing here has been proven its all theory. Thanks for your input either way!

 

That's surprising because most military airplane flight manuals are fairly accurate with this kind of thing, especially considering how much testing is done on the subjects contained in them. But what do I know...

Edited July 15, 2015 by Destroyer37

[NineLine]

OK, Sithspawn.

 

Your reply, is a pathetic internet thumbs down, red square, to add to my collection.

 

My argument is from, The Ordnance School Aberdeen Proving Ground Maryland, 1944.

 

What does it take ?

 

Let me know if you need any more.

 

 

..

 

 

#7-a-1 Application of Rockets is my favorite, as it talks about rockets having no 'recoil' for platforms that cant handle large amounts of recoil.... please see above, the video with the pick-up truck getting thrown around ;)

 

Also you can fire it from your hand, so go ahead and try that out with a 127mm rocket, I am sure the no recoil evidence you have shown will mean you will be fine. (PS I am not sugesting anyone try holding a HVAR in your hand an launching if you are some how able to get a hold of one ;) )

 

And no, I don't need anymore from you, thanks for asking.

Edited July 15, 2015 by NineLine

[FSKRipper]

OK, Sithspawn.

 

Your reply, is a pathetic internet thumbs down, red square, to add to my collection.

 

My argument is from, The Ordnance School Aberdeen Proving Ground Maryland, 1944.

 

What does it take ?

 

Let me know if you need any more.

 

 

..

 

Could you please explain the second point to me?

 

"Accelerations that are not excessive and that are easily controlled"

 

Could that be a physical factor on the plane? Could be that I'm totally wrong but I would read it not as recoil but the opposite thing. As long as the rocket is on the wing (veeery short) and the rocket ignites, it would accelerate this wing?

 

EDIT: I reread the thread and found this is close to the theory of the OP so forget it, I simply wait for the ultimative answer :)

Edited July 15, 2015 by FSKRipper

[Yo-Yo]

OK, Sithspawn.

 

Your reply, is a pathetic internet thumbs down, red square, to add to my collection.

 

My argument is from, The Ordnance School Aberdeen Proving Ground Maryland, 1944.

 

What does it take ?

 

Let me know if you need any more.

 

 

..

 

It directly compares rockets recoil to the recoil of the gun of the same caliber claiming about delicate constructions.

[Holbeach]

[quote=S

 

And no, I don't need anymore from you, thanks for asking.

 

Is that right ?

 

You don't need any more documentary evidence about no recoil ?

 

You would rather use the evidence of a Youtube video of a closed tube rocket launcher on the back of a truck. :helpsmilie:

 

Interesting.

 

 

..

Edited July 15, 2015 by Holbeach
Grammar

[FSKRipper]

Is that right.

 

You don't need documentary evidence.

 

So let's use the evidence of a video of a closed tube rocket launcher on the back of a truck. :helpsmilie:

 

Interesting.

 

 

..

 

Would be nice to get an answer from you. And perhaps the video? :music_whistling:

[Destroyer37]

See the video here, I don't see any recoil until the guns start firing.

[Destroyer37]

No recoil here either...note the HVAR rockets in the start of the film.

[FSKRipper]

Sorry, I see nothing from this video. A 70 year old guncam shrinked to 10 seconds of action without external view can't tell the truth. And by the way, the sub attack tips are crap.

But my question was directed at Holbeach. I for myself would vote for "negative recoil".

 

-> Nothing against you Yoyo, I'm only beginnig to understand prop and jet aerodynamics in it's details

Edited July 15, 2015 by FSKRipper

[Holbeach]

Would be nice to get an answer from you. And perhaps the video? :music_whistling:

Sorry I don't understand the question, so I've rewritten the post to make it clearer.

 

 

..

[Destroyer37]

Sorry, I see nothing from this video. A 70 year old guncam shrinked to 10 seconds of Action without external view can't tell the truth.

But my question was directed at Holbeach. I for myself would vote for "negative recoil".

 

-> Nothing against you Yoyo, I'm only beginnig to understand prop and jet aerodynamics

 

http://forums.eagle.ru/showthread.php?t=145003 This may help FSK

[NineLine]

Is that right.

 

You don't need documentary evidence.

 

So let's use the evidence of a video of a closed tube rocket launcher on the back of a truck. :helpsmilie:

 

Interesting.

 

 

..

 

Where did I say that evidence was enough one way or the other? You need to quite using your imagination so much. I recommended that we try and find a pilot with experience, like they have for the German planes.

 

Again, you should read what I have written before coming back with a snarky attitude. So far what you have shared is fairly vague, the page title is "Rockets General" hardly seems to be specific to what we are talking about...

[Flagrum]

Do I get this right here ... evidence that rockets produce some sort of recoil effect: the syrian truck video; the recoil-free behaviour of i.e. Mavericks (even bigger "rockets" than HVARs) is not considered relevant.

 

To put it into (some sort of) context: what exact weapon do we see in that truck video, what are the specifications?

[Destroyer37]

Wouldn't the Carl Gustaf blow a hole in this argument??? <- see what I did there?!?

[FSKRipper]

Sorry I don't understand the question, so I've rewritten the post to make it clearer.

..

 

 

My question was directed at your source of information. It implies that some kind of acceleration (no recoil) is happening when using the HVAR rockets.

 

 

http://forums.eagle.ru/showthread.php?t=145003 This may help FSK

 

Thx, I started reading. The video clips still show nothing significant to me. Will continue to read but if you like I have no problems with spoilers telling me that you see no recoil. I never claimed that!

 

From my point of view as a prop pilot and certified biophysicist I would stick with the OP theory.