davidbegg

A year or so back I purchased a GWS Beavers off an auction site. It flew beautifully, and was really enjoyable and fun to fly. However recently it has become a 'dog', with sudden dives turns towards the ground(To the right), sudden desire to climb steeply and when corrected to swoop suddenly towards the ground, a real handful to keep in the air. Nothing was changed, it just started to do this. I have reset the CG to 2' from the leading edge and checked the throws of the rudder, 3/4' each way and the elevator 1/2" up and down. Flies worse than ever. What have I done wrong? All surfaces are tightly attached , weight is well below the 14 oz (396 g). It has always had an outrunner motor and lipo battery, so it has heaps of power.

Thoughts I have had, to much down thrust or the motor pointing slightly off line???????, my CG figure of 2" from the leading edge is wrong?????????

Thoughts and suggestions are most welcome, I enjoyed flying my Beaver and I want the nice docile flyer back!!!!

Thank you.

Cheers

David

Wheelnut

My Feedback: (81)

Nice looking plane. That is wierd how it flew great before and now it won't. Something must have changed. From the picture, the down thrust looks fine.
I really don't know what it might be. Are you flying in more windy conditions than before?

-pkh-

My Feedback: (2)

Sudden desire to climb and dive usually indicates a tail heavy plane (CG too far back). This effect is often referred to as "porpoising", because when you try to fly it, you get a constant up-down-up-down motion as you try to keep it level in the air. The sudden dive/turns to the right are probably tip stalls that occur when it climbs.

Since the wing is rubber-banded on (giving some slop in alignment and CG relative to the wing location), and the fact that you said you re-adjusted the CG, this is what I would bet on. I'd move the CG forward 1/4" and see how it flies. The farther forward you move it, the more stable it will be. Just don't move so far forward that you need much up elevator to trim it for level flight.

davidbegg

No, yesterdays very unsuccessful fly was in perfectly calm conditions, the day was warm sunny and calm, just perfect for flying. I inially thought that it was wind as the park I went to fly it at had a gap between two hills behind it and I thought wind curents may have been funnelling through, but no definitely not wind.

Thanks for the suggestion.

Cheers

David

davidbegg

This was my thought as well as to the cause of the problem, but it has been checked and checked and yet checked yet again. At yesterdays unsuccessful fly attempts the battery was moved an inch and a half forward which must have made the plane slightly nose heavy and there was no change to its flying characteristics. I am tending towards thinking it may be something aerodynamic, something like a slight twist may have developed in the main wing???? I recently shifted cities and the plane was stored on a bed at my daughters house for a couple of months, and the quest bedroom door was kept shut. The room would have got very hot with the sun shining in the windows day after day and if the wing happened to be lying at an angle and had heat day after day????? I will check this out very carefully.

Thank you for your suggestions.

Cheers

David

FERNDALE AIR FORCE

David, I also have a GWS beaver, and mine got to doing funky things when I changed the motor and the prop. For example, an 10x8 prop would probably get the plane to fly very fast, but you are going to have all kinds of problems with control. Good Luck.

Tim

davidbegg

Yes I did chip the end off the prop taxiing around the drive ( playing silly bu***rs ) and replaced it one out of the prop box that I had on hand. I will check the prop size and 'cool it' down a bit to what it flew well with previously. You may have hit across a big issue that has not even been considered.

Thank you for your help.

Cheers

David

Wheelnut

My Feedback: (81)

It is interesting to me, how different planes act so differently to similiar upgrades. I have the Exceed Piper J-3 Cub. It flew great right out of the box, nice and gentle. But It wouldn't do a loop without going into a dive first. So I put in an out-runner and a 3s lipo and I was lucky. It flew great on the first try. The throttle response is much smoother now and of course alot more powerfull.

Original stock video
http://www.rcuvideos.com/video/Exceed-Piper-Cub-2-wmv

Outrunner upgrade video. It was very windy that day. I can fly a little better than that
http://www.rcuvideos.com/video/Brushless-Cub-wmv

davidbegg

Your Cub flies in a not dissimilar way to my beaver when it is behaving. I have no problem taking the Beaver off from the cut grass of the park.

Brushless motors are definitely the way to go with electrics these days.

Good flying.

Cheers

David

FERNDALE AIR FORCE

David, I thought I mentioned this before, obviously not, please verify that the extra thin foam on the elevator has not torn on the body line. It usually tears on the opposite side of the control horn. That would indeed give you a handful in the air.

Tim

davidbegg

I presume you are meaning the thin piece of foam joining the two sides of the elevator together where it goes underneath the rudder, and the horn is mounted on one side only, This in my opinion is not strong enough and is an obvious weak point in the design of this plane. It was repaired ages ago with a piece if flat carbon fibre, glued on the underside of the elevator, a light and strong repair. The actual elevator hinge is fine. (it is a full length tape hinge) and the servo moves the entire elevator up and down fine, even with some finger pressure on the ends to simulate the air movement while flying. I have 1/2" up and 1/2" down movement on the elevator.

Cheers

David

davidbegg

Well have just home from a great mornings flying. Had the Beaver up for about 15 minutes, calm, clear, totally gorgeous morning. It is exciting flying the Beaver, and while I did not crash, you had to concentrate hard and try to anticipate what it was going to do. Increasing the thrust on the motor has helped a lot, but I suspect that it is a partial solution to a problem, rather than correcting the cause of the change in the Beaver’s flying characteristics. Flying the Beaver now can be best described as mastering the challenge, rather than lazy enjoyment as flying the Beaver was previously. The positive is that flying the Beaver must improve your flying skills!!!!!

CG is correct, it has been checked and rechecked and rechecked again.
Everything is straight and mounted firmly
All the control surface throws have been checked and are set as per the instruction book.
Nothing I am aware of has changed from when the Beaver used to fly effortlessly. However obviously something has altered.

Straight flying = OK
Take off = OK
Landing once you are lined up = OK
Left turns, wants to dive, but not to badly and it is easily corrected, no real excitement at all with left turns.
Right turns, didn’t want to turn and when it did would climb, but not steeply and sort of ‘ stops’, forward speed was dropped off, when the elevator put the nose down the plane would start moving forward again and everything was fine until the next turn. The plane was showing no tendency to stall, but it would sort of hang in the turn at about a 30 degree angle to the ground.

I was flying at about half power as normal, but did try other power settings and the same things happened, faster at full power and slower at lower power but the same tendencies.

I have a brand new spare set of wings and tail plane, is it worth fitting these in case a warp or something has developed?

Any thoughts and suggestions??????? apart from retiring the plane?

Thank you, good flying.

Cheers David

Mr. Mugen

Is the dihedral on still? How about the tail, is it in line with the front of the fuse....not twisting? My super cub did this very same thing when the dihedral was greater than it was supposed to be. Just a thought.

Kevin

davidbegg

Finally located and fixed the problem with my Beaver, flew it until the battery went flat this morning, even though the air was 'lumpy' today and there was a bit of wind a few feet off the ground, and Beavers do not like 'lumpy' air or wind.

I feel embarresed to tell you the fault, stupid, stupid stupid!!!!!!

I had the engine thrust pointing to the left instead of the right, how I did it and how I didn't spot the error earlier I don't know!!!!! but I still did it!.

Thank you for your assistance.

There is always a reason, it just has to be located.

Cheers

David

Wheelnut

My Feedback: (81)

I'm glad you found it. So it wasn't such a mystery after all

davidbegg

It is amazing how you can look at something and check it many times, assure yourself it is correct, but it is not. Scary how the mind works, or doesn't work.

Guess this is how lots of serious accidents and mishaps occur, someone thinks they have done something correctly, checks it and makes the same error again and they truely believe there is no problem.

Peer support and checking of even model planes is essential.

Cheers

David

Wheelnut

My Feedback: (81)

I have done that many times.

davidbegg

Check out a couple of electric planes I am in the process of constructing, both have the thrust to the right, but with the Beaver, it was thrust to left, why i did it??????????????????????????????????

Over and out.

Cheers

David

davidbegg

Well guys I have finally solved my Beaver problems. The main reason for its erratic flight was the propeller. I used to use on it an orange GWS 8x6 prop. The plane flew really well with this prop, however these are very light weight props and I have found they break from the slightest knock. After the prop broke during shifting cities or while in storage in my daughters spare bedroom, I replaced the prop with a more substantial 8x6 Master airscrew electric prop, the plane was rebalanced to take account of the slightly heavier prop. However as previously described, after being in storage for 6 months, the Beaver flew atrociously and was not a pleasure or joy to fly. After ‘borrowing’ the Master airscrew 8x6 off the Beaver for another a plane, I put on the Beaver the only prop I had with me which was a master airscrew 7x5 electric prop. Well it is the Beaver of old again, it just flies and does everything asked of it without wanting to go dancing all over the sky. It can again be flown hands off the Tx for short periods of time! The master airscrew 8x6 prop must be much more efficient than the GWS 8x6 prop, or they measure the props differently, but the result was that the Beaver ended up being over propped which caused all sorts of grief.

Wheelnut

My Feedback: (81)

Wow! After all it was the prop. Glad you got it flying well again and I bet you helped out some other people that may have been having similar problems with their planes weather it was a Beaver or not.

davidbegg

I suspect that the very light weight GWS prop blades is flexing and moving relative to the prop hub thus reducing the propellers efficiency, down to where a similar amount of thrust is produced by the 8x6 GWS propto the 7x5 Master Airscrew prop. You never stop learning in this hobby do you. I knew that different brands of props were different but not to this degree.

Wheelnut

My Feedback: (81)

Yep, never stop learning and never stop flying
Before I got into planes, I knew very well that boat props make a huge difference in how they run.

sponginator

In the first pic it looks like the wing is offset or twister

davidbegg

Think the wing was fine at the stage when the photo was taken, however that wing did not enjoy being in my daughters closed spare bedroom with the sun streaming in for the entire summer, lost its dihedral and goodness knows what else, the temp would have got well over 40 degrees C for days on end.

The plane has a brand new replacement main wing to that shown in the photo, it helped but did not solve the 'dancing all over the sky' problems i was having with the Beaver.

David

FERNDALE AIR FORCE

My 6yo nephew is bugging me for a plane he can fly, and he is only semi interested in the Vapor. Maybe I should set up Mr Beaver for him, I could use 72 mghz and buddy box him. I might just get the plane set up and then have him practice not crashing.

Fern