Newbie Corner & Military Miscellaneous

UBanerjee · Post by **UBanerjee** » 21 Jun 2011 10:42

Rahul M wrote:UB, please see http://forums.bharat-rakshak.com/viewto ... 9#p1020089

So it is becoming BR->Internet->BR

Bolasani · Post by **Bolasani** » 22 Jun 2011 18:40

I was watching an episode of 'Jai Hind with Rocky and Mayur', on Combat Aviation Training School of Indian Army. There they showed a Dhruv simulating landing after the failure of 1 engine. The chopper skid along the ground for quite a few meters on land before coming to stop.

Could anybody please tell me how the loss of an engine translate to skidding on landing?

Thanks & Regards

shiv · Post by **shiv** » 24 Jun 2011 05:59

Bolasani wrote:I was watching an episode of 'Jai Hind with Rocky and Mayur', on Combat Aviation Training School of Indian Army. There they showed a Dhruv simulating landing after the failure of 1 engine. The chopper skid along the ground for quite a few meters on land before coming to stop.

Could anybody please tell me how the loss of an engine translate to skidding on landing?

Thanks & Regards

I am guessing here.

Rotating blades above the helicopter act like wings in the sense that they provide a lifting force to support the helo in the air in forward flight. Even toy helicopters with no power in the blades can be made to 'glide" like a fixed wing glider for this reason by providing a rotating momentum to the blades. If the helo is not moving forward that lifting force is not present and the helo can only stay in the air (stationary) by providing more power for rotation of blades.

If one engine goes the helo may not have enough power to descend vertically, but it has enough power to rotate the blades and "glide" and descend like an fixed wing aircraft, so it lands like an aircraft needing a runway rather than like a helo landing on a helipad. There is another thing called "ground effect" where the helo is able to hover close to the ground even if it is not able to hover higher up - but the safest way to descend to the "ground effect" altitude may be to "glide down", since a vertical descent with inadequate power may bring the helo down too fast. This is just my guess - not based on any real aeronautical knowledge. Helicopters that cannot hover 50 feet above Siachen may be able to hover 10 feet over Siachen because of "ground effect"

If all power is lost, the blades can be made to go into "autorotation" which will slow the descent of the helo - but it will still be a crash landing, not a landing.

Bolasani · Post by **Bolasani** » 24 Jun 2011 08:03

Thanks Shiv,

I will check out what Google Chacha has to offer regarding Helicopter gliding.

shiv · Post by **shiv** » 24 Jun 2011 09:36

Bolasani wrote:Thanks Shiv,

I will check out what Google Chacha has to offer regarding Helicopter gliding.

Actually Wiki aunty has some info
http://en.wikipedia.org/wiki/Translational_lift

Translational lift (also known as Effective Translational Lift, or ETL) is a transitional state present as a helicopter moves from hover to forward flight. This state provides extra lift, most typically, when the airspeed reaches approximately 16-24 knots, but is present with any horizontal flow of air across the rotor [1], and therefore can be present without any forward motion of the aircraft, given prevailing wind conditions.

The most common example of the effect is this: a helicopter might be slightly overloaded for take off so that it cannot hover. Liftoff can still be achieved if the helicopter has enough of a straight runway to make a "Running take off" where the pilot will slowly accelerate the helicopter across the ground until translational lift speed is achieved, extra rotor-disc lift is produced, and the aircraft will begin to climb.

In Robert Mason’s book[2], Chickenhawk, Mason describes a situation where an aircraft, loaded with 2500 pounds of high explosives, was above gross weight and should have been unable to achieve flight, was actually "coaxed" into flight via the "Running Take Off".

rajanb · Post by **rajanb** » 24 Jun 2011 18:28

Could someone please tell me how to post pictures on here?

Thanks much in advance.

Gaur · Post by **Gaur** » 24 Jun 2011 19:02

^^
You cannot directly upload pics from your hdd to this forum. You would first have to upload the pics to any free image hosting site (like photobucket). You can then post the link here.

Uploading to photobucket is very easy. You just create a free account there and press the upload button. Then a window will appear and you just select the files you want to upload.

rajanb · Post by **rajanb** » 24 Jun 2011 19:55

Gaur wrote:^^
You cannot directly upload pics from your hdd to this forum. You would first have to upload the pics to any free image hosting site (like photobucket). You can then post the link here.

Uploading to photobucket is very easy. You just create a free account there and press the upload button. Then a window will appear and you just select the files you want to upload.

Thanks Gaur. I presume that by link the pic will show on here?

Regards,

Rahul M · Post by **Rahul M** » 24 Jun 2011 19:58

yes. check the first post of misc pictures thread if you have doubts.

rajanb · Post by **rajanb** » 25 Jun 2011 09:54

Thanks a lot Rahul. Cheers.

rajanb · Post by **rajanb** » 25 Jun 2011 10:00

I have a few questions on aerodynamics, and would like to use the LCA as an example:
If the answers to this have been posted before would appreciate someone pointing me to the correct thread.

With the MKII having an uprated engine F414-IN6 and assuming that weight of the Tejas remains constant, will the following happen?

a) get the ability to supercruise?
b) Improved AoA?
c) be able to fy at 1.8 mach or higher?
d) be agile and mre manoueverable in WVR combat.
e) Achieve -3/+9G?

Many thanks. I used to be an aviation enthusiast 40 years back, but then, alas, the burden of work and extensive travelling paid put to that.

Gaur · Post by **Gaur** » 25 Jun 2011 11:57

^^
Just a few guesses as I have no expertise in this matter. I hope that the gurus would correct me where I am wrong.

a> Maybe. It surely will have enough thrust to do that. Rest will depend upon the drag. Also, it seems that the wave drag will get reduced in mk2. So who knows? If ADA manages to keep mk2 within designated weight, I see no reason why it should not be able to supercruise.

b> That is given from day 1.

c> No. To go beyond that speed, the aircraft requires variable geometry intake. That leads to lot of moving parts which further leads to increase in complexity, cost, maintenance requirement and rcs. Since the days of high speed interceptors are over, speeds over Mach 1.8 are no longer necessary. What is of more importance is acceleration (and hence thrust).

d> Of course.

e> Once the flight envelope is fully opened, that will be achieved in mk1 itself.

rajanb · Post by **rajanb** » 25 Jun 2011 13:45

Thanks much Gaur. Cheers.

manish.rastogi · Post by **manish.rastogi** » 25 Jun 2011 15:15

RahulM saar as suggested by you I downloaded that Daniel P raymer's Aircraft design book, but its quite old in my opinion like 1989's edition. Also I am low on time and can afford to read one book only.
So can you or anyone else please suggest a good aircraft designing book(latest preferably

) asap! Please!!!!

Raghunath · Post by **Raghunath** » 25 Jun 2011 19:01

manish.rastogi wrote:RahulM saar as suggested by you I downloaded that Daniel P raymer's Aircraft design book, but its quite old in my opinion like 1989's edition. Also I am low on time and can afford to read one book only.
So can you or anyone else please suggest a good aircraft designing book(latest preferably ) asap! Please!!!!

I'm no expert myself, but I found A.C. Kermode's book "Flight Without Formulae" very helpful. Its short, and expounds the basic concepts very nicely.

I think he also has book titled "Flight With Formulae" which I read some years back in college. That was pretty good too, very clearly and logically put.

I'll try getting Daniel P. Raymer's book if Rahul Sir recommended it.

manish.rastogi · Post by **manish.rastogi** » 25 Jun 2011 20:20

You can get it online as free ebook, otherwise get ready to pay ear 4K INR!!
And I will try to get or see your recommended books.
Thanks!!

Rahul M · Post by **Rahul M** » 25 Jun 2011 20:46

guys I am not from the aero field myself but it was recommended by an aero friend of mine. I found it quite lucid. btw, unless you are interested in hypersonics and stuff not much has changed since 1989.

manish.rastogi · Post by **manish.rastogi** » 25 Jun 2011 22:51

Yes,it is pretty much clear and easy to comprehend, but I thought that if some book could provide practices and methods of this age with better and new examples, it would be better. Anyways, lets see!

Bob V · Post by **Bob V** » 25 Jun 2011 23:44

try these books :
Mechanics of Flight by AC Kermode (the most apt for a layman)
Aerodynamics for Engg students by Houghton & Carpenter.

manish.rastogi · Post by **manish.rastogi** » 25 Jun 2011 23:49

Thanks a lot Bob!!

siddharth · Post by **siddharth** » 26 Jun 2011 07:53

I was watching "The death of Osama" on the discovery channel last night. They claim to have used Lockheed Martin RQ-170 Sentinel stealth drone not only to confirm osama's presence in the Abbottabad compound but also to monitor the raid that killed him. Is there an armed version of this drone??

UBanerjee · Post by **UBanerjee** » 26 Jun 2011 10:30

X-posted....

What's the best/easiest way to write in Devanagari online? I have the plug-in that shows the text for reading purposes already.

AdityaM · Post by **AdityaM** » 26 Jun 2011 16:53

Does a warship have fishing nets to catch fresh food for self while on peaceful patrol?

Rahul M · Post by **Rahul M** » 26 Jun 2011 16:58

^^

UB, how about gmail ? I can write in bangla too.

shiv · Post by **shiv** » 26 Jun 2011 17:04

AdityaM wrote:Does a warship have fishing nets to catch fresh food for self while on peaceful patrol?

If it does, I have never heard of it. Warships carry basic survival equipment along with life boats, and equipment for some form of fishing is a given - but not for routine use.

abhishek-nayak · Post by **abhishek-nayak** » 26 Jun 2011 17:36

Guys, Can you Tell me who is this kashsoldier???

Klaus · Post by **Klaus** » 26 Jun 2011 20:40

Do all submarines compulsorily have to feature rubber anechoic tiles in their design? Is this feature part of the design manual or code-book in every design establishment across the world? The reason I am asking is that the U209 and U212 German submarines, primarily assigned duties in the Baltic supposedly do not have them. Is is due to the friendly political environment of the region?

UBanerjee · Post by **UBanerjee** » 26 Jun 2011 22:41

Rahul M wrote:^^

UB, how about gmail ? I can write in bangla too.

You mean gmail has built in devanagari writing?

Edit:

Cross-posting

ManishH wrote:
UBanerjee wrote:What's the best/easiest way to write in Devanagari online? I have the plug-in that shows the text for reading purposes already.
With google chrome, there's a transliteration plugin which is quite convenient http://t13n.googlecode.com/svn/trunk/bl ... lp_hi.html

If writing longer documents (html, latex), itrans (http://www.aczoom.com/itrans/) is better.

Works brilliantly. बहुत अच्छा है.

Rahul M · Post by **Rahul M** » 26 Jun 2011 22:52

UBanerjee · Post by **UBanerjee** » 27 Jun 2011 00:14

Beautiful, thanks.

pragnya · Post by **pragnya** » 29 Jun 2011 12:02

@mods

is there a thread for putting cartoons?? i am interested in putting them. am trying them out and hope to post regularly or possibly will post a link to my blog. these are not military related but i may try some down the line.

TIA.

gakakkad · Post by **gakakkad** » 29 Jun 2011 20:19

why is the bullpup config more popular in modern assault rifles?

nachiket · Post by **nachiket** » 29 Jun 2011 20:26

gakakkad wrote:why is the bullpup config more popular in modern assault rifles?

It reduces the length of the rifle for the same or longer barrel length. It is also easier to fire a bull-pup rifle with one hand if need be.

Cain Marko · Post by **Cain Marko** » 29 Jun 2011 22:37

what would you say are the primary characteristics of a 2nd gen fighter as against a 3rd gen one ?
please reply in newbie thread. this is going OT here.

In answer to Rahul garu's query above, my guess would be the presence of a radar. IIRC, the gen 3 a/c such as the Mirage F1, MiG-23, and F4, all came with an FCR, the MiG-21 did not until much later?

CM.

Rahul M · Post by **Rahul M** » 30 Jun 2011 01:50

yup, among other factors. you might want to check the mig-21F13 V mig-21bis table I posted in the mi avia thread.

arijitkm · Post by **arijitkm** » 30 Jun 2011 20:37

http://www.flickr.com/photos/64675684@N04/5887393223/

A newbie question.
The (above) picture of Snow Shooter is on DRDO website photo gallery.
What's the snow shooter ? And how it works ? Any details....

Thanks.

abhishek-nayak · Post by **abhishek-nayak** » 30 Jun 2011 21:56

My sister wants to give air force entrance exam for engg grads(AFCAT)

i want to know

1) can a final year engg student apply for the test?

2) what are the books available for AFCAT test.

Singh · Post by **Singh** » 30 Jun 2011 22:23

arijitkm wrote:http://www.flickr.com/photos/64675684@N04/5887393223/

A newbie question.
The (above) picture of Snow Shooter is on DRDO website photo gallery.
What's the snow shooter ? And how it works ? Any details....

Thanks.

As far as i know a snow shooter is a snow clearing vehicle which spray's d snow away from the road instead of just piling it on d road side.
Now I have no clue how the thing in tht pic a snow shooter

arijitkm · Post by **arijitkm** » 01 Jul 2011 10:41

^you mean, it's look like bulldozer (which clear soil, rubble etc).

But in the picture (also link from DRDO page
http://drdo.gov.in/drdo/productsgallery ... HOOTER.jpg )

It's look like hydro dam.
How it functions ? what's the utility ?

Any guess ….

Thanks.

AdityaM · Post by **AdityaM** » 05 Jul 2011 21:50

At 1:45 min, the rockets release and parachute down, only to suddenly pick pace to penetrate ground.
so why did they have to slow down with parachutes to start with? why didnt they use the additional free fall velocity?