Sign in to follow this  
Followers 0

I have always wondered " what if "

15 posts in this topic

Posted

I have always wondered what if the springs or bungees let go on the front of my skis. Well last week when I took off with my SkyRaider I found out. I had to rig my skis to my taller landing gear before I could fly. The temp wasn't to bad so I figured it would be a good day to get them installed. I made all new riggings but used the same old bungees. With everything done I jacked the airplane up and checked to make sure the bungees pulled the front of the ski up and held it. Everything was a go. Taxied out to the grass and tried them out, looked good so away I went. In flight I had to retrim the airplane. After that it flew hands off. Great night of flying. A week or so later I went back over to the hanger to fly. This time the temp was much colder. Preflight looked good. Away I went. As soon as I broke ground I new something wasn't right. The airplane wanted to nose dive into the ground. I had it trimed after my last flight so I new exactly what was wrong. I looked down at my skis and both where pointing down. Hmmmm this should be interesting. I could rock the wings and the left one would come up but not the right one. After thinking about it for a couple of minutes I thought I might as well fly until dark to burn all the fuel off I could, beside it was a beautiful night. On the way back to the airport I had figured a plan out. If I slowed the airplane down enough the left ski would come up, that left me with only one problem,my right ski. I figured pavement would be better than snow and grass to land on because if the ski tip hit it would slide on pavement. I was light coming in, so I came in as slow as I could with no flaps to keep my nose up as much as I could. With a little power in a nose high attitude I put it down on the left ski first then settled it down on my right ski. My AOA was enough for the rear wheel on my right ski to contact the pavement first. Everything was cool. I am thinking the much colder weather affected the old bungee cords. Could have been a costly mistake to save $3. 

 

 

 

3 people like this

Share this post


Link to post
Share on other sites

Posted (edited)

Bandit,

Maybe not so much on experimental planes, but all the certified planes I saw had a safety cable on the front that wouldn't let the ski go tip down, as well as the bungee.   Glad you kept your wits and figured out a safe way to land.

EDMO

Edited by EDMO

Share this post


Link to post
Share on other sites

Posted (edited)

On the skis I built for the Avids, I always unhooked the bungees from the skis when I put the plane away.  I did use cheaper bungee cord from the local Farm And Fleet type of store though, and didn't want them to streach out when they weren't being used.  I used a spring hook like on a dog chain at the end of the bungees.  Glad it all worked out for you!   Jim Chuk

new skis 001 (Large).jpg

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted

Jim,  I can see the safety cable on yours - didn't Bandit have one on his skis - or was it too long?

EDMO

Share this post


Link to post
Share on other sites

Posted

The bungees on my rigging are getting tired too.  The last time I flew them, I had tip droop.  Luckily my limit cables are short enough landing on pavement wasn't a problem, too. This is the main reason for being precise about the length of the front limit cables.

Share this post


Link to post
Share on other sites

Posted

Jim,  I can see the safety cable on yours - didn't Bandit have one on his skis - or was it too long?

EDMO

I'm sure he had limiter cables on the front, but the bungee holds the front of the ski up so that the back limiter cable is tight  while in flight.   Apparently his bungees were to weak to hold the tips up.  ( I've heard there is a pill that helps to hold the tip up, but I don't think it works on planes)  Jim Chuk

Share this post


Link to post
Share on other sites

Posted (edited)

Jim,  I have never used skis - Do you set the front cable so that the ski is level for a wheel landing, or for a tail-down landing?  Would it be set different for wheel skis?  With the amount of snow we get here, we either land on it with wheels, or wait for the runway to be plowed, or stay home!

Thanks,  EDMO

Edited by EDMO

Share this post


Link to post
Share on other sites

Posted

The tip of the ski is supposed to be set so that it is about 4 degrees up compared to the flying attitude of the airplane.  Nose down is supposed be about 20 degrees.   There has to be enough movement in the skis so they can go over bumps without running out of room/slack on the limiter cables.   Jim Chuk

Share this post


Link to post
Share on other sites

Posted

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

Jim,  I can see the safety cable on yours - didn't Bandit have one on his skis - or was it too long?

EDMO

Ed, I had everything rigged right, just had weak bungees.

Edited by Bandit

Share this post


Link to post
Share on other sites

Posted

Experience is so much fun.....

MarkD

Share this post


Link to post
Share on other sites

Posted

AC 43.13-2B chapter 5 has lots of details about skis. Not a bad idea to review it if you are planning any ski flying. Angle of incidence of the ski is very important. To much up as in rear limiter cables to long leads to very spooky handling indeed. http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 43.13-2B.pdf

Share this post


Link to post
Share on other sites

Posted

My skis are rigged right, I just had bad bungees in super cold temps.

Share this post


Link to post
Share on other sites

Posted

Don't know if this will help much. Or if correct. But I was informed not to follow the sec 43 for ski riggin in ruff/wilderness flyin.     I was told once u set all ur riggin to put 60lbs of pull on bungies to keep ski tip up in flight and rear cable tight.   And for my riggin I followed Atle Dodge paperwork.  Does that sound right or wrong? 

Share this post


Link to post
Share on other sites

Posted

Back in the 60s in Alaska bungees cord was made from some kind of natural rubber.. It still was elastice at -40.. Starting around 1968 , the MFg. changed the composition of the bungee(shock cord) and if stretched in cold weather, would take a "set" and not pull the toe of the ski up after takeoff...  That old natural rubber shock cord I am not sure you can get it any more.. THis is one reason lots of folks went to using springs instead of shock cords.....

 

WHen the plane is sitting 3 point, the front bungees is stretched a lot... and if it is 0 or colder, will likely take a set......

 

 

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0