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+--Forum: General Discussion
+---Topic: Hap hover descent speed started by Porcupine

Posted by: Porcupine on Mar. 17 2017,03:38

When using Dirk's HAP the hover descent rate is very slow.  I am happy with the ground movement speeds FWD/BCK/Left/Right  but is there a way to increase the actual descent rate please? Cheers Dan
PS: I try to search the forum before posting but as is the case with most forum sites, the topic titles can be quite vague and therefore searching almost impossible. Perhaps as a newbie, may I suggest that people choose their topic headings to more clearly identify their issue ( I appreciate that can sometimes be difficult however)

Posted by: LONE WOLF 61 A on Mar. 17 2017,13:42

just put fassbender in search and 350 results showed up buddy ! :cool:
Posted by: Porcupine on Mar. 18 2017,04:24

I appreciate your assistance but it just shows what I am trying to say. 350 results and not one of the topic titles leads to my particular issue. Once I get a solution in this post, then when someone else has this particular issue all they have to do is search their same issue and my topic title will most likely appear first and will save hours of searching topics that give no indication of what the topic is about. :D
Posted by: Kyrelel on Mar. 21 2017,05:46

My curiosity was drawn to this topic by the vague title :/

Anyhow, I have used Dirk's AP on countless occasions and I cannot think of a scenario where you would want the descent speed to be faster (I assume you are talking about the last 10-20 feet). What is it that you are trying to do?

Posted by: Porcupine on Mar. 22 2017,11:02

Maybe I am just trying to land too fast like military Huey's dropping off troops in a hurry. I thank you for your curiosity. :)
PS: For my curiosity, how would you have titled this topic ???

Posted by: PhantomTweak on Mar. 22 2017,19:36

A friend of mine on another forum, FlightSim, to be precise, was an H-34 and CH-47 pilot in Viet Nam. He got shot up badly on a mission, which ended his flying career. He described the type of descent you speak of, the fast troop drop off. No AP used. All hand flown. It took some practise, but the newer pilots just followed the more experienced pilots. Learning by doing, so to speak.
They would make sharp course changes, sharp descents, and ascents. Anything to try and throw off the enemy's aim.  They would come down fast when they hit the LZ, whether taking fire or not. Then arrest the descent at the last minute, and go into a hover about 5 feet off the ground. The ground effect helped, but as the troops dismounted, they had to hold the hover long enough for them to all get out, which isn't easy. Fully laden troops weigh a lot! Not to mention the heat and humidity made their power available/power required a close thing, making climbing out after the troops were out a problem.
And they would want the troops out as fast as possible. Helicopters can't flatten on the ground, and make great targets. The enemy learned that one helicopter equals several troops, so if they can bring one down it's a big bonus.
Anyway, the approaches to an LZ were hand-flown, not AP. Best way to learn it is to do it. You may make a lot of smoking holes, but without someone's example, it will be a steep learning curve. Turn off the AP, forget it while doing this sort of thing. And you will want to overload the helicopter's weight a little, say 50-100 lbs to simulate troops. A fully laden infantry man can weight 250 lbs, and they could carry 4-6 of them. You do the math. Make the outside temp 90° F, if you can make the humidity 80-90%, light winds.
Now, from 2-3000' AGL, descend as fast as you dare, say 1500-2000 FPM, and arrest the descent as near to the ground as you can, while maintaining forward speed until AT the point of drop-off. Make the descent angle 45-50°. You'll then have to reduce the weight to simulate troops jumping out, but keep the bird 5-10' off the ground.
Then pull pitch, but don't overload the engines or cause the rotor RPM to "droop", and fly away, maybe jinking left or right as you do.

That was how it was done. Pretty much still is, too. The H-60 just carries more weight. They still perform about the same maneuvers to troop drop-off.

Good luck!

Posted by: GmanM on Mar. 22 2017,21:07

I've heard Vietnam era pilots describe the fast single ship landing/low hover much like a powered autorotation.

However, formation landings may not have been quite as predictable since the pilot's may not have had the leeway to monopolize a portion of the LZ other than to make last minute dodges to avoid trees and stumps.

As PhantomTweak mentioned, the weight, density altitude, temperature, and wind direction would make any fast landing a sporty proposition, not to mention the possibility of hostiles firing at them. Unloaded, the fast landing would be less stressful, at least until the troops hopped-in with the bad guys close-by firing from the treelines.

Definitely NOT a suitable use of any autopilot, even today such tactical landings would be flown strictly by hand.


Posted by: Porcupine on Mar. 22 2017,23:57

Thankyou. Advice much appreciated and will be followed. Obviously my poor choice when using AP Thank heavens we can turn crash detection off so that the manouveur can be practiced!!!So much respect for those Nam guys.
Posted by: GmanM on Mar. 23 2017,04:00

It's funny that thinking about a fast landing causes me to think back to the first Bell 206 in FS. Back then I didn't do anything for a long time but crash. It's like they had the torque really dialed up back then and as soon as you broke free of the ground you were spinning. Granted, the anti-torque learning curve was in play, but still I spun, and spun, and crashed and crashed.

I remember I was flying out of Hana on the island of Maui, and trying to someday fly up to the crater of the Haleakala Volcano.

It finally got to the point where I realized that taking off was like riding a bike, and then it was take off.
Of course hovering was still problematic, and landing was straight forward, as long as I didn't mind crashing half the time.

Over the years I spent a lot of time flying to and from landing towers, (The World Trade Center was my favorite), raised helipads, off-shore towers, etc, which allowed me to gain a lot more finesse in my landings, and I found myself  getting slightly bored with the careful controlled slide down an invisible cable (in my mind) down to the landing deck.

The alternative?
A fast hotshot controlled crash, which I again compare to a powered auto-rotation because there is no careful controlling down to a fixed helipad, just pick a spot and get there like the bird is about to blow up and you don't want to be in it when it does, preferably landing into the wind.

So yeah, just pick a helipad at an airport so you have something to aim at to simulate a hot one ship LZ, and then put her down as quickly as you can. Yeah, you will dig some holes, but practice makes perfect.

If I recall the method from the book "Chickenhawk" the Air Cav pilots on a combat assault would fly as high as possible for as long as possible to stay out of ground fire range, then as low and fast as possible over the tops of the trees, also to avoid giving enemy marksmen a clear shot,  and then down to the LZ in formations which were designed to allow the door gunners clear fields of fire without shooting each other. That was the theory anyways.

Bottom line is to just start doing it, and you will figure it out by trial and error, just remember to try to give yourself some wind, and then land into the wind which will provide a cushioning force to flare into, and more lift when taking off.

Have fun


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