Chris's Webbit

[Big Bandit]

Very smart Chris . I'll weigh mine later to see just what the standard build should be.

Cheers,

Chris.

[Chris Bott - Moderator]

Steve no, wingtips are the piece of balsa from the kit. I only used one of the pieces each side mind you, not the full sandwich.

 

Maybe I put them on backwards? No only joking, no one would do that

[Steve W-O]

Posted by Chris Bott on 09/04/2011 09:00:18:

Steve no, wingtips are the piece of balsa from the kit. I only used one of the pieces each side mind you, not the full sandwich.

 

Maybe I put them on backwards? No only joking, no one would do that

 

 

OK, must be the angle. I changed mine, also using one piece of balsa, but a different shape.

 

[Chris Bott - Moderator]

Looks great Steve. Has she flown? Is she close?

[Steve W-O]

Everything is ready, haven't fitted the spats yet (another couple of ounces )

 

Ran the motor up this morning, my do taxi tests this afternoon, and I want to put an EagleTree recorder into it before flying.

 

[Chris Bott - Moderator]

Nice

 

Eagle Tree? That's another couple of ounces lol.

Edited By Chris Bott on 09/04/2011 10:52:52

[Steve W-O]

Posted by Chris Bott on 09/04/2011 10:52:33:

Nice

 

Eagle Tree? That's another couple of ounces lol.

Edited By Chris Bott on 09/04/2011 10:52:52

 

 

Just weighed it, will use an old V2, the logger, expander, altimeter and airspeed sensors weigh exactly 1oz. The pitot and tubing is already installed, except the 1" external piece. You can see the socket on the port wing.

[Chris Bott - Moderator]

Yes I know, look at the weather, should be out flying.

 

However things are getting done. I succumbed to peer pressure on here and at the 11th hour have gone for wing dowels and bolts. I just hope the leading edge holds up as I didn't add any reinforcement inside.

 

Finally the Vtail is glued on. If it's out of line at all now, that will have to be dealt with by trims.

 

A little more covering to do, if I was at all artistic I'd know what I was going to do with coloured trim. Whatever it gets will be whatever happens when I do it!

 

Next I'll hook up the ruddervator snakes and she'll be flyable from then on.

 

This last one was an attempt to check the Vtail alignment. I hope I was holding the camera offset from centre, otherwise I have a real banana.

 

[Chris Bott - Moderator]

i might not be flying but it's lovely working outside in this sunshine.

 

V tail sorted

 

UP

DOWN

RIGHT

LEFT

Edited By Chris Bott on 09/04/2011 14:05:08

[Chris Bott - Moderator]

She's survived her first crash! Came in to do these photos, went back out to find her upside down on the floor. I shouldn't be so daft as to leave her on a garden table on a gusty day.

 

A bit of a setback too. Thought I'd just connect all 5 servos up and give the sticks a good waggle. To test the ESC's BEC of course. Well, didn't that get hot! I could still hold my finger on it but only just. As the models survival depends on the BEC a rethink is in order. I'll go and see what other options I have in stock.

[David Ashby - Moderator]

Very nice job Chris and Steve

[Richard Harris]

Steve, Chris,

 

A couple of fine examples

 

Perfect day today for a maiden?

[Steve W-O]

Posted by Chris Bott on 09/04/2011 13:41:28:

She's survived her first crash! Came in to do these photos, went back out to find her upside down on the floor. I shouldn't be so daft as to leave her on a garden table on a gusty day.

 

A bit of a setback too. Thought I'd just connect all 5 servos up and give the sticks a good waggle. To test the ESC's BEC of course. Well, didn't that get hot! I could still hold my finger on it but only just. As the models survival depends on the BEC a rethink is in order. I'll go and see what other options I have in stock.

 

 

 

 

Sorry to hear it, hope no damage.

 

(note no wheels on mine, last things to go on, stops it sliding off the bench etc)

[Chris Bott - Moderator]

Richard yes, looks like a perfect day for a maiden. Yesterday was also apparently a perfect day for a gardening and barbeque, especially as the whole family is here, which is rare these days.

 

Today both the garden and the maiden are beckoning. Hopefully I'll get enough of the former done that I will allow myself out to do the latter.

 

Virtually no damage Steve when it blew off the table. I can see a tiny crack in the underside trailing edge sheeting near one tip, but I'm happy to leave well alone.

 

I've swapped the ESC for a 55A with SBEC one. I can't detect any heat in that at all when giving all the servos an exercise.

 

Watch this space for a flight (or otherwise) report later.

Edited By Chris Bott on 10/04/2011 11:56:17

[Chris Bott - Moderator]

Back in one piece, but far from pleasurable flying. Somethings wrong and I haven't sorted it yet. No time to explain now, I'll describe the flights later on.

[Steve W-O]

Very good, first one!

[Chris Bott - Moderator]

OK, memory is already fading so here's what I do remember.

Two flights from one battery, landing in the middle to make some adjustments.

Most of the flights were under power, at 1/3 to 1/2 throttle.

 

The "VeeBit" seemed to get out of shape really easily and without warning, but thankfully was easy to get back into a stable straight and level each time.

It took a fair but of down trim for level flight.

Aileron/elevator turns to the right were easier than to the left. In left hand turns the tail really dropped.

 

Rudder was far too effective so was mostly left alone, when used sparingly it helped the turns. Rudder also had quite a roll component, interestingly this was in the conventional (same direction as the applied rudder) direction rather than the roll I expected from ruddervators acting as ailerons.

 

To try to even out the turns, more and more left rudder trim was added.

After this, a glide was tried and a lot of aileron had to be held in. BUT I can't remember which way! So that has to be tested again.

Adding aileron differential helped the turns, but not enough.

 

It looks like roll was trimmed straight with power on but suffered in the glide.

 

A third flight was attempted with some weight up front to see if this would help the nose stay down in the turns. However I over compensated on takeoff, dropping the power off too much to help straighten things out and VeeBit ended up coming down quite hard. The only damage sustained was a loose wing dowell in the leading edge. As I added no reinforcement here, I may well revert to wing bands. But this stopped flying for the day.

It was well over powered, so in case any of this is torque related, a smaller prop will be used next time. I'll go again with the standard C/G, but I'll have a 4S A123 with me in case I want to try C/G forward again.

I'm tempted to reduce right thrust and increase down thrust.

 

I was getting plenty of advice at the field, all conflicting of course

 

I'm wondering about the head on photo above, how much is the Vtail completely masked, in the wake of the wing? Would this cause a huge difference between power on and glide conditions?

 

Any ideas will be most welcome.

 

 

 

 

[Steve W-O]

What about changing the mix so that the down going elevon when used as a rudder has more travel than the up going one, that will help it keep the tail up in turns. It would also help reduce the roll component you mention

 

In what way did it get out of shape quickly? Wondering is this is a feature of the Webbit, or the Veebit? The shape of the wing tip is prone to tip stalling (the reason I changed mine).

 

The difference in roll between power on and off (or high and low speed) could on some planes be a twisted wing, but with the ailerons on the Webbit I don't think that would be the case, nor do I think your wing would be twisted!

 

 

If you got conflicting advice at the field, where people could see it, I wonder about all the different views you will get here

[Chris Bott - Moderator]

I think you're right Steve, I'm going to have to sort out one thing at a time. Good job I like a challenge.

 

I'll have a think about your elevon idea. Trouble is, every time I had a bright idea yesterday it seemed like any changes I made had other side effects.

 

Out of shape - very difficult to describe, as it seemed different every time. But often it was the wings ending up vertical when I thought I'd put in a similar amount of aileron as the last good turn I did. It did tip stall a couple of times, but this was different and often the tail was well down too.

 

Yep I'm confident the wing is flat. It's possible that one of two leading edge dowels was loose before the heavy landing, this could have meant the wing was moving around?? However, people who had a good "feel" of the model during the afternoon think is was pretty solid. I'm very tempted to go to wing bands now.

 

Not sure when I'll get out with it again though. Off working away from home again later today.

[Chris Bott - Moderator]

I've now changed what I want to change before I have another go. But can't get out now for over a week. (There may be a small window maybe on Friday but it's unlikely).

 

I have a 9x6 prop instead of an 11x5.5. I've reduced rudder throw. I've taken out most of the right thrust and added more down.

I've fixed the wing dowel.(although bands would be more secure, maybe with leaving the dowels in to center the wing?)

 

Here is a shot where I've positioned the camera so that I can't see either the top or the bottom of the Vtails. It all seems to be suitably straight well except the U/C that I seem to have bashed.

 

 

[Danny Fenton]

Looks pretty straight to me Chris Look forward to hearing how the next flight goes.

 

Cheers

Danny

[Big Bandit]

Hi Chris,

 

Looks straight to me as well, I was hopeing to maiden mine last weekend as well, but it didn't happen. Just too may other things got in the way, like two sessions with the T28 and easy Cub. The wings are finished now though and ready for covering, so providing I'm not sidetracked again this weekend looks good for it.

 

Cheers,

 

Chris.

[Vecchio Austriaco]

Nice build. With your enlighted version you can enyoy the evening thermals....

By the way - as mine is already flying - the flaps are not such a bad idea after all - it flies faster than I thought and also as it is a trainer you can train your skils in flying with flaps open and so on.

VA

[Chris Bott - Moderator]

Thanks Vecchio. That was part of the reason, to train the thumbs in the use of flaps.

 

I may go and have another test tonight, unless it starts to rain!

[Chris Bott - Moderator]

Back from the field again, very happy 'cos I can announce - ALL SORTED.

 

Happy webbitteer now as I have a model that does lovely low lazy slow circuits as well as vertical climbs and lovely huge loops etc. Inverted needs almost no down elevator. Rolls can be axial or barrel as required. Glide slope is pretty good too.

 

However, spins - forget it! Well I couldn't get it to do anything close to a spin tonight.

Stall turns, much the same, very hit and miss, nearly all miss to be honest.

The rudder still drops the nose, a lot, so I have to play with throws and expo there still.

It knife edged for a little while but was very wobbly with corrections and soon rolled out.

 

The flaps had an effect, but not much of one, need to play with those more. Trim was hardly upset and landing approaches could be steeper without picking up speed, but that was about it.

 

I did manage to provoke a stall eventually, at that point a wing dropped quite violently, but it just mushed for quite a while beforehand. Maybe I should try this for the spin entry?

 

So, what fixed it?

Well a number of things. Prop size, removing all sidethrust and adding lots of downthrust.

 

The prop size is a bit puzzling. I found the previously used motor in a box with an 11"x5.5" prop on it. I tested that and got about 340W so stuck with it.Since then I've changed the ESC because of the BEC overheating, but I didn't check if power changed (I wouldn't expect it to).After the first test flights I went straight down to a 9"x6" prop to reduce torque effects and did a power test. This is with the new ESC of course. Now I'm getting 320W. So that doesn't add up. But it works.

 

At the field tonight I added even more downthrust after flight one. This is in an attempt to stop the model climbing under power. I'll post a picture if I can take one of the downthrust it has now. It looks rather a lot!

 

So there we are. Very happy with it now. So now I can spoil it by adding more coloured trim etc.