Author Topic: Descent angle on approach  (Read 10460 times)

Doug Johnson

Descent angle on approach
« on: March 16, 2012, 11:00:41 AM »
Nasa paper on STOL landing approaches
They used c/n 505  N4153D   1958  H-395 at Langley research centre Hampton,  VA   NACA, It was flown by Bob Champine NACA BELL X-1 Test Pilot, (now deceased) in 1959 for his personal pleasure. Bob was fortunate enough to get to enjoy both ends of flight the slowest landing to fastest flight.

I find the research study and paper interesting  becaue I personally after some practice found it easier to make a stol landing using a steeper approach.

Franek actually found this paper and pointed it  out to me.


« Last Edit: March 16, 2012, 03:51:23 PM by Doug Johnson »


  • Guest
Re: Descent angle on approach
« Reply #1 on: March 16, 2012, 06:07:34 PM »
The black & white photo clearly shows that the test airplane for this article is a Helio Courier H-391B, if you look closely you'll see that the airplane has the two-blade 101" Hartzell.

It is probable that the same N-number was carried on at a later date.

Also the test airplane has a 260 HP engine, which clearly denotes a GO-435-C2B2-6

Ken Berger

Re: Descent angle on approach
« Reply #2 on: March 17, 2012, 01:10:33 AM »
I find that even though the overall path may be steeper, the most comfortable angle of attack does not point down nearly as much as the usual piper or cessna when flying the path to final.  It's more of a controlled sink rate.  Do others find the same?


Re: Descent angle on approach
« Reply #3 on: March 17, 2012, 06:11:16 AM »
Depends of the load of the day.  And the mission of the day ( surface to land ).   My friend with his 250, always lightly loaded, does his approaches always with slats out, full flaps, controlling the descent with power.  He takes crosswind in the face, and land on the width of the runway if the wind ask for it.

Me, with my 295, i always fly overload.  Sometimes with weight that are close to what the military were flying the Helio. No way for me to try to do it like my friend.  I don't want to go behind the power curve since it had destroyed more Helio than bad weather.  Probably always heavily loaded Helio.  Even if my 295 have 44% more static pulling power, i feel that it is not enough power to control the sink rate when all the drag producing lift enhancement are deployed ( slats, flaps, high AOA ).  On floats, i also have to deal with the stalling of them.  On my configuration of floats, they tend to make buffeting about 4 degrees more angle of attack after the slats did pop out.  Lightly loaded, i can ignore those buffeting and the associated drag.  Overweight, i can't.  My ex 800 had a mention in the supplement POH for the PK floats that in case of a motor failure, a minimum of speed was needed in order to make a rotation  ( i can't remember how much, may be 95 mph , 85 k). I tried it, and it was true on certain weight & balance.  And untrue if loaded in the back.  So a "slats out" approach on floats, when highly loaded, was a dangerous option.

I just want to point out, since statistics learn us to take care of the "behind the power curve" in a Helio, that there is not only one approach method.  Being comfortable with one way to do it, having practicing it in a certain weight configuration, or plane configuration ( floats, skis, wheels) can be too challenging to do the same when loaded differently.

The good part of it is that it is not so complicated to choose the approach.  Slats are there to help us to see what's happening.  Keeping them in when heavily loaded from 100 feet to 10 feet of the ground and we will always have an energy reserve to kill that sink rate.  After all, these wings are flown from below 3000 pounds, to 4000 pounds and higher.  With the same wings.  Normal that we can't do our approaches the same lightly loaded than heavely.

« Last Edit: March 17, 2012, 06:16:22 AM by Louis »

Doug Johnson

Re: Descent angle on approach
« Reply #4 on: March 17, 2012, 05:18:41 PM »
I don't believe the reuse of registry numbers is the case here I can't make out the emblem on the door or lettering on the fuselage in another picture of N4153D being flown off the glacier I am posting. Slightly blown up I beleive the Helio  in question is an H-391.

There was a reference to the glacier being in Canada or southern Alaska and it being an atmospheric or weather study moslty was about the recovery. And in ref to Bob Champaine it had no ref to model or c/n just Helio yr flown 1959 and registry number.

I forgot to mention that the c/n 505 was in question. In my N list which I copied c/n is highlighted in yellow to indicate it is in question.

It fits in the list in the last of the 391's  possibly 095, 098, 100, or 101 those are all in question as well, since we have pretty much ruled out being a H-395. I will list it as unknown c/n in the N number list since I don't have enough for a questionable link to a construction number.


edit; c/n 099 now N10CJ, 1958, H-391B;   Wasilla,  AK, orig N4153D, NACA /NASA test plane, flown by Bob Champine 1959, photo, now owned by Louis Lacher
« Last Edit: April 14, 2012, 03:48:42 PM by Doug Johnson »

Doug Johnson

Re: Descent angle on approach
« Reply #5 on: March 17, 2012, 08:01:11 PM »
I posted this paper to get some feedback on steep descent because of my practice of using a steeper descent with the Helio.

I like Kens "Controlled sink rate" it's a nice descriptive way to put it and the way I think of it.

My Landings were generally more about descent angle and judging the spot to begin the descent than anything else so I would use as little of my reserve power as possible and have it use with my reserve lift gained by not using slats until my round out, I did not like to get behind the power curve or at least as little as possible. like louis I was usually at legal gross (I tried to be at least at legal gross after fuel burn when landing with passengers) but more often I was  military gross when hauling cargo. I often used my outboard fuel tanks to haul gas other than Avgas for other vehicles. When at military gross I always tried to be well within cg limits and was more careful about predicted turbulence. I usually, only used 30 degrees of flap when at gross and 20 degrees at military gross on landing since I didn't feel that I needed the increased drag I was already descending steeply enough. I like Louise' "Term military gross".

I only let slats come out when rounding out or deliberately slow flying. The slats are such good "best angle of attack indicators for your speed" no matter what load you are carrying and I wanted reserve lift as well as the reserve power to use it. I already find myself using Louis' "Term reserve lift" and that is how I used the slats for the slowest possible touch down speed.

I generally had my rpm at around 2700 when I began my descent and was around 2100 when I was at my round out point around 35'. I tried to let gravity control my descent and my descent angle controlled my speed which was just above slat deployment. once I became accustomed to the slats I really didn't pay much attention to airspeed.On the round out my rpm came back up to 27-2800.

If this sounds like anyone Else's technique would like to hear more.

I wonder if having flaps fully deployed at military gross and using more power in the round out would cushion the landing more?

It would take away any chance of doing a go around though, once the slats came out, generally
the case anyway.

Edit, I went back and carefully read what Louis posted and I've almost repeated what he said.
« Last Edit: March 18, 2012, 08:55:07 PM by Doug Johnson »


Re: Descent angle on approach
« Reply #6 on: March 18, 2012, 09:57:59 AM »
I wonder if having flaps fully employed at military gross and using more power in the round out would cushion the landing more?

Personnaly, i use full flaps 90% of the time.  But some Helio pilots would never do it.  This guy was saying to me that he never use full flaps.  And he was good.  Trained in Alaska by high time Helio pilots.  He bring us on a river.  The river was finally a mud river.  Totally uninteresting, dangerous, and undrinkable.  A very good canoeist here, Bill Masson, had always said " Never paddle a river you can't drink".  So after two days, we decide to get out by plane.  Phone the same guy with his Helio, found a patch of sand to land on, and a couple of hours later he was there, was about to take all our stuff, and fly us out from a very short patch of sand.  He was able to bring us back to the airport were we had left our planes.

The Helio is an incredible plane.


« Last Edit: March 18, 2012, 09:59:53 AM by Louis »

Doug Johnson

Re: Descent angle on approach
« Reply #7 on: March 19, 2012, 10:11:06 PM »
You said "Personnaly, I use full flaps 90% of the time", what do use the other ten percent of the time and why?

My helio had never had the gross weight increase kit installed. when I was putting my helio together I had a long talk with Larry Montgomery about the gross weight kit he didn't seem to think it was needed and Clarence Brent's kit was added weight. that the helio was plenty strong. He did think the larger antiservo tab was useful and made the airplane easier to fly.

One thing about a steep approach on descent I had a barrel of fuel slide forward and at my low power setting,  I nearly ran out of up elevator when I started to round out, but increased power brought the nose up. Scared me a little.

I was usually flying at least one direction at least at legal gross 3400. Up to about 3600 lbs I normally used 40 degrees of flaps 3800 lbs 30 degrees and I probably never flew over 4000 lbs but in that area I used 20 degrees. It just seemed to work better. Above 3600 lbs is not where I really liked to go so that was why I was asking if I would have been better off to use 40 degrees of flap. I was always concerned landing over gross I'd break or overstress the landing gear.

I don't want anyone to think I have thousands of hours in a Helio but usually flying the Helio I was hauling something, and why waste a trip without being at gross.

I can only remember one delivery where I was lightly loaded a friend had broke down in a weasel track vehicle. There was no place to land in miles, Supercub or Helio, so we did an air drop, wouldn't have won any contest in precision bombing, but we delivered a bunch of electrical parts and a carburettor without breaking them. Long range fuel helped because we had to hunt for them. I suppose nowadays you would use a GPS coordinate and fly right to them. And they would call on the cell phone. They had a couple hand held aviation radio's they were using for communication they managed to contact an airliner (Northwest airlines I think) passing over and was able to pass a message to John's wife who called me. Old memories.

About that water you couldn't drink, my sister sells marine safety equip and clear back in the 90's got me one of those reverse osmosis filters so you can drink that water. One go around with beaver fever and you boil the water but that glacier silt is still a little thick.

« Last Edit: March 20, 2012, 11:21:49 AM by Doug Johnson »

Jason Stephens

Re: Descent angle on approach
« Reply #8 on: April 14, 2012, 01:18:53 PM »
Louis, those are great photos.  98D is actually my Dad's old airplane that I grew up flying around in.  He got it shortly after I was born in '73 and then sold it to the Branhams in the 90's after we moved to AZ.  Glad to hear a good pilot is flying it.  I contacted the owners about it and they have it on floats now.

All my experience flying the plane was on floats and relatively light.  We used full flaps almost exclusively except for my early training. 

Doug Johnson

Bruce Stephens N4198D
« Reply #9 on: May 18, 2012, 11:43:29 AM »
Another picture of N4198D. Bruce Stephens as pilot circa 1973.

« Last Edit: May 18, 2012, 11:51:16 AM by Doug Johnson »

Lance Goodwinm

Re: Descent angle on approach
« Reply #10 on: June 24, 2012, 07:00:04 PM »
Hello all

I hope I am doing this right.
On the photos of N4153 I would like to say that they were taken in the Yukon on the St.Elias Icefields.
The machine was buried for the winter because of a lost engine.
Found and dug out in the spring.
Not the first Helio that was landed on the glacier system due to a lost engine.
It spent a very productive life here working for the Arctic Institute of North America (that is the AINA logo on the door) doing a lot of hauling personal and gear back and forth from Kluane Lake headquarters to the St. Elias.  I have a lot of photos gathered from various people that worked on the HAAPS program run in the late 60's and 70's.  It was a high altitude physiology project ran by the late Dr. Charles Houston.
I will endeavor to post some of the very interesting photos shot of AINA pilots landing and taking off on Mt. Logans massive plateau @ 17,500' ASL - 18,000' ASL.
The photos I will attach are shot by a member of the climbing party Thomas Lyman, of N4153D and N4166D.



« Last Edit: June 24, 2012, 07:05:15 PM by BushApe »

Doug Johnson

Re: Descent angle on approach
« Reply #11 on: July 04, 2012, 02:44:13 PM »

A couple photos of N4153D in 1960's  from Lance Goodwin.
it along with N4166D above was used for the high altitude physiology project that took place  at Kluane Lake Yukon.  The Arctic Institute Of North America ran the program, that's the logo on the side.

Lance Goodwin"s Father-in-law has been flying Helio's his whole career in the St. Elias Mts (40yrs) and worked and flew Chales Houston all over the Ice fields.

He was one of the pilots that flew the Helio onto the Mt.Logan Plateau at 17,500' for hundreds of take off's and landings.  Dr Charles Houston was the main investigator in the High Altitude Physiology Study.

The first photo Is 66D in its winter bed the second a lot of shoveling and inspection of some wing damage.


« Last Edit: July 04, 2012, 02:49:08 PM by Doug Johnson »