A Tale of Two Takeoffs

Great write-up. I've also learned the importance of a well briefed experienced wing runner, and letting it sit wings level "until the sloshing noise stops" before takeoff. I do have one question, however. How does extended spoilers improve aileron response? They're inboard of the ailerons on a standard class glider, and therefore should have zero aerodynamic effect on ailerons, except for contributing to total drag and reducing acceleration...(probably an impercievable amount at low speeds, since weight and stationary inetia is the larger factor to overcome, not parasitic drag). I've seen many people use this technique in contest flying, and I never understood it. The only argument that I could maybe see is giving some drag stability, much like hanging out the landing gear does to a large aircraft. And even then, it just adds complexity to an already high workload segment of the flight.

Again, I think your post is both informative and a great pointer for anyone staring to carry water ballast or inexperienced in flying a CG hook. I'm mainly just curious as to why people use the spoiler on takeoff technique.

Jordan

Jordan, I have heard several "reasons" for using spoilers on standard class gliders. First of which is that the spoilers "board" the air out ward and increase flow over the ailerons. Second that "spoiling" the lift on the raising wing will let it come back down. I tend to think the first is closer to the truth. But from personal experience in an ASW-19, it works. I didn't really believe it until I tried an experiment. When landing, I put the spoilers away on the last half of the rollout not using the brake untill one of the wings started to drop and I had full aileron deflection in and it continued to drop. At this point I was traveling at around 10-15 mph, when I then opened the spoilers the wing imediately came back up and stayed there until I was down to less than a couple of mph. All I really know is that it works.

I flew hundreds of hours in a CG hook Pegasus and never used spoilers during a takeoff. No problems.

gkemp

I don't recall using spoilers or not with my ASW-19b (CG hook), but I
always used spoilers and negative flaps with my LS-6a also a CG hook)
and found that to be an improvement. I continued using negative flaps,
but no spoilers, in my LAK-17a (CG hook), and had no problems there, either.

In Chip's case, I agree with his assessment that the main cause of
trouble was the partial ballast load shifting outboard on one side
(inboard on the other).

On 6/17/2017 6:22 AM, gkemp wrote:
I flew hundreds of hours in a CG hook Pegasus and never used spoilers during a takeoff. No problems.

gkemp

--
Dan, 5J

Spoilers open on takeoff works. Until you're trying to take off high altitude, hot, cross-downwind, full of water, you won't notice the need. Then you will. You get a crucial second or two of better aileron control.

Thanks much Chip for the good post. Wing running is a constant problem at contests. I've had several incidents where despite my careful briefings, contest wing runners just can't get it right. The wings must be balanced, level, sloshed through the baffles, but if there is a significant cross wind (mifflin), the upwind wing cannot be high. You must run. This is not a 2-33. Runway lights make it a higher priority.

It's hard to whine. The wing runners are volunteers, and spending a long hot day running wings for cranky pilots cannot be fun. Still, along with slow tows, this is a constant problem at contests, and perhaps more regular emphasis by contest management would help.

(Why must every contest start with a litany of "towplane alpha bravo, more speed please." "towplane alpha bravo, more speed please.".... )

John Cochrane

Yup John you are whining 😀. If you need and desire the best for you, wing runners and tow pilots, you can bring them along or better yet be a wing runner for a contest. All are volunteers and they do the best they can and contest management do the best with the resources available.

Ron:

Thanks, and I really did hesitate to say anything, as I hesitate and hesitate again to complain at contests. On the other hand, we do have a problem of wing drop after wing drop, sometimes causing damage, once causing damage to a spectator, and the problem is not hard to fix. We also have a constant problem of too slow tows with ballasted gliders. Everyone gets used to flying without ballast over the winter I guess.

Perhaps you can help with social suggestions. While showing my deep appreciation for the volunteers and towpilots, who give up their free time and suffer in the sun all on my behalf, how can I get the message across -- wings must be balanced, slosh ballast through baffles in tanks if need be, they should be darn close to level -- which is hard to see given winglets, and a contest glider wing at familiar shoulder height is way too high -- and if there is a crosswind, it is imperative to have the upwind wing at least level if not a foot low at the moment of release. Plus, run. How do I say that really politely, and show the deep appreciation that I really do feel?

It is frustrating to be sitting on the side of the runway, in the dust, bottom of the wing all scratched up, on account of an easily preventable error..

John Cochrane

Sorry for the delay but am hiking in Germany with limited time and Internet access. My comment about whining pertained to RAS Posts not about speaking up at contests. I cannot speak for others but the contests I have assisted with in thee ground we review everything you mention and we strive no wing drops and appropriate tow speeds.

Of the 700 or so tows at Nephi last year during the Nats I recall 9 wing drops, I do not have m,y notes in front of me. I saw them all, including the one that started this thread. No one common denominator in these incidents. Can we them all? I hope so but human nature is a tough nut to crack

For tow speeds we review with the chief tow pilot, all pilots at the beginning and when we hear for speed calls. Again no excuses but many factors attribute to this situation. Some calls for speed are erroneous when items released such as waffle balls are used to protect rope end and the glider ASI tube is in the nose with the tow hook! I have heard pilots calling for more speed when the tow plane was already doing 75+. We remind pilots about this situation but it still happens every contest I have been involved with.

Getting all pieces together for a contest is a delicate dance with many partners. I do not know any folks organizing contests that does not put safety first. So yes speak up if necessary and better yet lets you and every other contest pilot on t he ground assisting and contributing to the solution at once a year.

One other note concerning tow speeds, it is going to get harder going forward. The latest high wing loading racing gliders are requiring 85 knots at a minimum, according to the manufacturer. Many tow planes while able to dro the speed do not climb as well at those speeds. Sol faster tows may. Mean lower tows which could mean higher tow fees.

Ron Gleason

On Saturday, June 17, 2017 at 11:40:18 AM UTC-4, John Cochrane wrote:
Spoilers open on takeoff works. Until you're trying to take off high altitude, hot, cross-downwind, full of water, you won't notice the need. Then you will. You get a crucial second or two of better aileron control.

Thanks much Chip for the good post. Wing running is a constant problem at contests. I've had several incidents where despite my careful briefings, contest wing runners just can't get it right. The wings must be balanced, level, sloshed through the baffles, but if there is a significant cross wind (mifflin), the upwind wing cannot be high. You must run. This is not a 2-33.. Runway lights make it a higher priority.

It's hard to whine. The wing runners are volunteers, and spending a long hot day running wings for cranky pilots cannot be fun. Still, along with slow tows, this is a constant problem at contests, and perhaps more regular emphasis by contest management would help.

(Why must every contest start with a litany of "towplane alpha bravo, more speed please." "towplane alpha bravo, more speed please.".... )

John Cochrane

I don't fault the wing runner.
It was Chip's responsibility to have the glider with acceptable wing balance.
Possibly a very experienced wing runner might have stopped this event, but most don't have the experience or judgement.
This is the second case of serious wing drop due to balance at contest I have flown at this year. The other resulted in a glider not flyable.
The lessons I see he
1-The pilot must be careful to ensure balanced loading.
2-Line crews need to be trained to recognize imbalance and be prepared to stop the launch to correct. The line boss needs to be ready to confirm the problem or declare good to go.
3- We all need to ready and more incline to end a bad start.

FWIW
UH

While I'm in an inquisitive mood, here's another one. What speed are you flying when you thermal your ballasted glider in a 45 degree bank in a gaggle, allowing for the extra energy required for surprise maneuvering? What speed were you being towed at 15 minutes earlier that resulted in your vhf complaint for more speed from the tug driver? Since you're flapped (I'm assuming), what flap setting are you using on tow? Trying to better understand this...

Jordan