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shane.barton
10-10-2006, 08:47 AM
I just wanted to report that I snapped my first set of wings today using a heavy duty hi-start from Great Planes! Here's the scenario....

It was a relatively calm day, approx. 8mph winds coming in from the east/north-east. I strung out my hi-start at the edge of my field and attached my Vista. I walked about 25-30 paces and did and test run. Everything seemed to be in order and she was flying relatively well from what I could see. The next time around I got a little bit ahead of myself and decided to do about 40-50 paces. Connected my string to the plane, wiggled my sticks to ensure everything was moving appropriately, and let her rip! She shot up good and strait, I said to myself, I said "Self, that was what it's all about!". At the apex of the climb, or so I thought, I dipped the nose and pulled back on the stick to let the line come off the plane. All I heard from there was "snap!"..."Crunch!". The next thing I know is I saw my plane spiraling to the ground with both wing tips touching together! From where I was standing, it did look pretty neat, until I realized what had just happened, then I said some nasty sailor words (I happened to be a sailor BTW), and continued to say not so nice things as I was walking over to the downed plane. Sure enough, the right wing snapped just to the left of the wing joiner. Luckily, we have some very tall grass in our field and the fuse and the electronics inside survived nicely. After assessing the damage, I remembered that I had ordered an extra wing set just to be safe (WOO-HOO I can keep flying today!!). After attaching my spare wing and setting up the hi-start again, I realized I should just keep it to about 30 paces for the h-start for a while. My flights from there were pretty uneventful until the last flight which I bunged up my approach when a freak gust of wind came up and flipped my plane nose first into the pavement. That nose dive pretty much crunched my nose and split the fuse up to the LE of the wing. Now I guess it will be easier to put in that motor I have been talking about, and to recover the whole plane with a scheme Iím happier with. I will post some pics of the fuse and the wing so I can get some suggestion on how to go about fixing everything.

shane.barton
10-10-2006, 08:53 AM
Oops! This pic failed to upload with the rest of them.

-Shane

Up&Away
11-09-2006, 02:35 PM
Ouch!
I may not see properly, but is there a main spar in the wing?

cbatters
11-09-2006, 02:58 PM
Sorry to hear about the damage to your plane. Looks all too familiar from my early days of flying. (I gave up the hobby for 10+ years after spending more time repairing than flying. I picked up the sport again when I bought some cheap RTF that were tough enough to withstand crashes that would have caused major damage to a balsa fuse/wing.)

Looking forward to putting my 2M foam glider / highstart and electric sailplane back in the air.

Good luck with your motor upgrade.



Clint

shane.barton
11-12-2006, 10:16 PM
I have the covering off but am without a camera at the moment. Will take some pics and post them, that way I can get a definate answer on if what I am thinking is the spar is in fact a spar.

AEAJR
11-18-2006, 08:18 PM
I have never broken a wing on a hi-start and mine is rated for 4M planes. I launch Spirits and Gentle Ladies at 12 pounds of pull.

Perhaps there had been some damage to the wing that you had not noticed.

I am sure you can fix it.

cbatters
11-21-2006, 08:02 PM
shane.barton

What was the config of your high start?

______ feet of ____ " surgical tubing

______ feet of ______ nylon line


I launched my 2M glider this weekend and was thinking about your post while doing it. (I have always pulled back on the stick a little to maximize altitude but then pushed forward on the stick to release and assume a proper free-flight attitude.)

With my hi-start setup I can only launch up to about 100' in calm weather but still flew a couple laps around the field before landing.



Clint

AEAJR
11-21-2006, 10:48 PM
Unless you are pulling way too much force on launch I don't see how that could happen on a launch. Well, one way would be if you had a strong hi-start pulled to a strong pull, say 12 pounds and early in the launch a big gust hit it. Maybe that could over stress the wing. But clearly the tape joint held.

Was there any tear or break in the covering, particularly on the bottom of the wing? The covering material adds a lot of strength to the wing and if the is torn and unrepaired, especially on the bottom you can lose some important support.

Just guessing here. No accusations. Could have been a defective wing.


In refererence to launching technique.

I never use the elevator on launch unless the nose of the plane turns up too much in which case I push down.

If you feel you need to use the elevator to get more altitude but otherwise have a good flying plane, try moving the hook back a little. Nothing wrong with using the elevator but moving the hook back would be indicated by that behavior and will give you a better result.

Typical hook location is about 1/4" in front of the CG but contest pilots often put it right on the CG. See what works for you but the closer to the CG the steeper the climb and the more height.

I toss my Spirit out ( the plane in my fleet that most closely approximates the Vista) at about 30 degree angle and give it a good hard push. It rotates to about a 60 degree angle on a calm day and may go as high as 75 degrees with a good breeze of say 7 mph, with no elevator at all.

If your plane has a built up wing, there are several things you can watch to judge if you are over stressing the wing:

1) watch for wrinkles in the covering material. A little is usually OK as it first leaves your hand but if you see wrinkling as you go up the line, give it a little down to relieve the stress.

2) watch for wing flex. If your wings seem to be flexing more than just a little, then again you might be over stressing and again, a little down will relieve that stress. This can occur in gusty conditions as the gusts will flex the wings.

3) When you zoom, if you zoom, if you see a pronounced "flap" of the wings then you may be over stressing them. This is far more likely off a winch than a hi-start.

If you have a two piece wing that you join at the field onto a wing joiner, as the Spirit does, tape that joint, ( I see that you did ) all the way around, with packing tape. This transfers most of the stress to the covering and the wing structure and somewhat off the joiner. Most of these wing joiners are not that strong and will flex under load. If they flex enough it can lead to a separation of the wing halves and that can be bad!

I may have posted some of this earlier so forgive me if I duplicate.

I launch my planes with a pull equal to about 3-6 times their weight. So, if you have a 2 pound Vista, you want it to leave your hand with at least 6 pounds of pull with 2 pounds being the upper range. You can use a fish scale to measure the pull.

Don't go 6X right away, build up to it and watch for indicators of stress. If you see too much stress, then don't go that high. Just because my Spirit can take 12 pounds does not mean your plane can.

A well balanced hi-start/plane combo would have that 3-6X pull hit that force at a full 3X the length of your rubber. This will give you a steady even pull all the way up the line. Hitting 5X the weight of your plane at 3X the length of your rubber would be excellent.

By contrast, mine is not well balanced for a 2 meter plane as it is intended for 3-4 meter planes. I get 6X ( 12 pounds of upll) at 1.5X the length of the rubber. That is to say I would like to have 10 pounds of pull at 300 foot pull on a 100 foot piece of rubber. My hi-start hits 6X or 12 pounds at 150 feet, so I get a more explosive launch. Much more stressful on the plane.

Hope this is helpful.

cbatters
11-22-2006, 12:43 AM
At least with my wimpy high start setup, I had to push the nose down a bit forward in higher wind to keep the plane from stalling but could pull back a little in calm conditions to coax a little more altitude out of the launch. I'll check CG relative to hook.

On my last launch, I gave the plane a serious hurl upward and was pleasantly surprised at the result. (In the past I have just let go of the plane and let the high-start do all the work.)



Clint

AEAJR
11-22-2006, 01:40 AM
Even when I launch off the winch, whatever plane I am launching gets a hard throw. That gets it up to flying speed much faster, makes it much easier to control and gives me higher launches.

shane.barton
11-24-2006, 11:34 AM
Sorry I haven't had a chance to reply lately. As far as the specs on my Hi-start, it's a standard Hi-start from Great Planes. I cannot recall how much tubing it comes with. I know I was about 50-100 feet short of string (my 2 and 4 year old decided they wanted to unwrap my string for me). I don't have a fish scale, I usually do about 30 paces for launches. I had done several launches at 30-40 paces with no problems. I did not happened to notice any opens in the covering, flexing of the wings, or anything out of sorts. When I realized something was awry is when she pulled alittle to the right and up (up-elevator, but not my input), and then the "Crunch-snap". perhaps there was an underlying structure faulty in the wing. I may never know. I haven't had too much time to work on the wing due to my work schedule.