HP14

On Wednesday, January 18, 2017 at 12:38:37 PM UTC-8, SoaringXCellence wrote:
...It seems the -14 had a properly sized tail surface. So no "waddle" that came with some earlier v-tail designs.

Well, it depends. The standard HP-14 plans set shows the HP-14 as having the same size tail as most of the Schreder birds from the HP-11 through the HP-18. Steve Smith once did a stability analysis of the HP-14 that shows it to have a relatively narrow margin of static stability. That's not necessarily bad, but it does mean greater pilot workload than were there a greater margin.

Several HP-14 builders made larger tails for their ships; some by using longer skins and spars, some by adding extended tips to the ruddervators.

I've flown HP-11 and HP-18, but never HP-14. But anyhow, my impression is that they're not all that hard to come to terms with. The hard part is learning to deal with the 90-degree landing flaps. They offer about the best glidepath control there ever was, but the dearth of similarly-equipped two-seaters means that you pretty much have to learn to use them on your own.

BTW, don't believe the haters who say that once you crank on the flaps you can't back off. That's just bull****. I've gone from full positive to get down onto the deck, full negative to float all the way to the turnoff (halfway down a 9000-foot runway), and then back to full positive to get down and stopped, all during the same approach. It's once you figure out the feed-forward trick.

--Bob K.

I have about 20 or so hours in an HP-14 and 60 or so in an HP-16. Also have about 1400 hours in a Zuni, so fair amount of flaps only time.

The key with flaps is simple. You know that when you open spoilers, you add drag and you have to lower the nose to maintain speed. Well, flaps add drag, too, so you have to lower the nose because of this to maintain speed. Then, there is the secondary effect that is really primary. Draw a line through the leading edge and trailing edge of the wing. Note this angle on the fuselage, and relative to the tail Now, drop the flaps. Keep that line fixed at the leading edge, and the trailing edge of the flap. See how it is now tipped significantly relative to the fuselage and tail? You have effectively just added a bunch of incidence to the wing, so to keep it at the same angle of attack, you have to push the nose down. Inverse is true when you retract the flap. You have to pull the nose up as you retract the flap, as you reduce the effective incidence and angle of attack. That is what Bob means by feed forward. Add flaps, lower the nose. Reduce flaps, raise the nose. Until you are ready to touch down, you MUST stay above flaps up stall speed. If you do this, it is a piece of cake to do what Bob described.

As to your initial question.

Pros:
Not highly sought after, so low cost of entry.
Very good performance for what you have to spend. Nearly the equal or early Std Class Glass at 1/3 to 1/2 the cost.
Metal, so no gelcoat issues of you decide to tie it out.
Not too bad to assemble. Each one may have tricks to be done, such as order of installation of pins. On mine, it is Drag pin, lift pin, then main pins. On another I know of, the drag pin is the last pin on each wing. Learn the plane.

Cons:
Low entry price means low exit price and limited market to sell to.
Impression by others that they are "heavy and hard to assemble". The plane does carry more of its empty weight in the wings, but it is not too bad. A third person is helpful if you don't have a wing rigging dolly, simply because the root chord is 40 inches and the flap needs to be aligned with the driver as you bring the wing in to place.
Trailers are often not well thought out on Homebuilts. The builder spent all his energy on the plane, and the trailer may be an afterthought. Work on fixtures, and amaze your friends with how easy it is to rig.
It was a project when it was started, and it can remain a project for ever. Homebuilts have more opportunities for changes to be made than factory builts.

Why don't I have more time in mine? I have too many other toys!

Steve Leonard

Yeah, what Steve said!
--Bob K.

On 1/21/2017 12:36 AM, Bob Kuykendall wrote:
Yeah, what Steve said!
--Bob K.

Ditto everything Steve L. & Bob K. have said. That's with 2260 hrs in
landing-flapped-only gliders, 196 in an HP-14...nearly always rigged/derigged
each flight, never with more than one additional person (on the wingtip,
including - more than once! - a 5', 120-ish lb lady
glider-pilot/fellow-club-member-friend, wingtip helper on the HP-14). Most
everyone readily offers hearsay, typically without labeling it as such, the
more so when it comes to "non-mainstream gliders." Sometimes, it's even
"generally accurate"...though the devil is always in the details. Best to get
the details from those with first-hand experience.

The only reason I sold my HP-14 when I did was it (1981) fell only into the
open class had I chosen to fly it in contests, and I wanted a ship in which if
I came in last I'd be certain it was due to the pilot and not the ship.
Wonderful bird, which encourages/rewards attention to rudder use, at least in
the as-designed-span, V-tailed, form.

Bob W.

I owned a HP-14 for 15 years, and got many hundreds of hours of flying in it, including a bunch of XC flying. Sold it because it was damaged (while tied down on the ground, something else hit it) and I didn't want the rebuilding project. Despite roughness in the finish due to age, the glide slope (at lowish speeds) was great, thanks to the span. With a bit of positive flaps it could work the weakest lift. And with plenty of flaps the short field landing ability was great.

But, with my weak back, I personally found the rigging difficult, even after building a device for manipulating the roots. I usually kept it rigged all season. The prospect of a difficult rigging, plus the condition of the aging trailer, made my XC flying rather conservative to avoid landouts. Thus I ended up flying more XC after I switched to a glider with less performance but much easier rigging (Russia AC4).

I should also mention that, despite having adequate tail surfaces etc, the thing never "flew itself", it was hands-on all the time, perhaps due to the mixing of rudder and elevator inputs into the V-tail. And the aileron control forces were a lot heavier than the tail, and roll rate slow. Nothing difficult in the handling, but not quite the friendliness of many glass ships of later design. If you have a strong back, and can get a good trailer for it, then it would be fine.

Don't know if I should jump in here or not, but I remember a fatal Austria accident where the pilot was attempting a full slip to landing. Probably holding full aileron and opposite rudder as necessary to line up with runway. As the V tailed Austria crossed the fence, it suddenly pitched down hard and the pilot was killed. There was some discussion about a sudden application of full rudder (one ruddervator up, other ruddervator down) may have stalled the up member, resulting in full down input from the remaining ruddervator.
Something to think about if flying a V tailed bird,
JJ

On Wednesday, January 25, 2017 at 12:29:04 PM UTC-5, wrote:
Don't know if I should jump in here or not, but I remember a fatal Austria accident where the pilot was attempting a full slip to landing. Probably holding full aileron and opposite rudder as necessary to line up with runway. As the V tailed Austria crossed the fence, it suddenly pitched down hard and the pilot was killed. There was some discussion about a sudden application of full rudder (one ruddervator up, other ruddervator down) may have stalled the up member, resulting in full down input from the remaining ruddervator.
Something to think about if flying a V tailed bird,
JJ

The Austria SH-1 POH/FM cautions not to do a full slip since the wing turbulence can mask the entire tail. I did it - once - at 5,000'; in full slip, the elevator and rudder went limp and wagging the stick did nothing. Cycling the dive brakes did nothing. About 1,500' later, it spontaneously decided to fly again, as I was preparing to 'step out'. This was quite near max aft allowable C of G (but within limits). I never did a full slip again, and was happy I'd waited until I had a lot of air under me to do this test (flying from a winch-only site). I read POH's with a lot more attention before flying new types. A half-control slip with full top-and-bottom dive brakes in the Austria gives pretty good descent rate. I loved flying the Austria, within the limits the book gave.

On Wednesday, January 25, 2017 at 10:29:04 AM UTC-7, wrote:
Don't know if I should jump in here or not, but I remember a fatal Austria accident where the pilot was attempting a full slip to landing. Probably holding full aileron and opposite rudder as necessary to line up with runway. As the V tailed Austria crossed the fence, it suddenly pitched down hard and the pilot was killed. There was some discussion about a sudden application of full rudder (one ruddervator up, other ruddervator down) may have stalled the up member, resulting in full down input from the remaining ruddervator.
Something to think about if flying a V tailed bird,
JJ

A Schreder HP or RS has 90 deg flaps which pretty much precludes the need to side slip the sailplane - around 3-1 glide angle with full flaps. Once I got the flap/aileron mixer where I liked it on my RS-15, I really looked forward to landings. It was great fun!

Mike

On 25/01/2017 19:29, wrote:

Don't know if I should jump in here or not, but I remember a fatal
Austria accident where the pilot was attempting a full slip to
landing. Probably holding full aileron and opposite rudder as
necessary to line up with runway. As the V tailed Austria crossed the
fence, it suddenly pitched down hard and the pilot was killed. There
was some discussion about a sudden application of full rudder (one
ruddervator up, other ruddervator down) may have stalled the up
member, resulting in full down input from the remaining ruddervator.
Something to think about if flying a V tailed bird, JJ

Off topic for an HP14 thread, but I once owned a share 15m Austria SH.
You could definitely stall the V-tail with one movement (rudder or
elevator) and effectively loose all control of the other. BUT this only
happened at low speeds - well below the wing stalling speed.

It manifested itself with a few quirks. During the landing or take off
roll, if you used just enough forward elevator to lift the tail, you had
full rudder control. Any other elevator position would compromise rudder
authority. In a few other low airspeed situations, like spin recovery,
or at the top of a loop where the wings were "flying with zero G's", you
could induce V-tail quirks. But for normal flying it was no different to
flying a conventional glider.

I had no trouble with side slips but I was careful to keep the CG
position well within the handbook range. There was also a mod to the
Handbook which reduced the allowable CG range. The V-tail mounting
structure was also subject to glue joint failure, with mandatory mods. I
checked it very carefully before each flight. Also the V-tail
attachment. If one V-tail was not positively locked during rigging, the
results were ugly...