Seagull Grob Tutor G115

[David Ashby - Moderator]

Coming along nicely Mike.

I fed the rudder steering rod through that hole in the former on the assumption it was intended as a guide?

 

Edited By David Ashby - RCME on 16/08/2013 08:08:11

[MikeS]

Thanks David. I did run the control rod through the guide but found as the metal is very think unlike the throttle control rod I felt it put a lot of strain on the coupled rudder servo. It seems to work fine without the guide.

Well today I added foam to the rx and sat and used hook and loop to secure them. I also attached the canopy to the removable hatch. As per my norm I used small light screws to hold the canopy on as I have never been a fan of glueing them and means I can easily remove it if needed.

I reamed out the hole in the white plastic spinner to fit the 70 and also fitted the small landing light in the cowl. Once this was done I re-checked the CofG and it is about right which means it will be nose heavy as I have not fitted the cowl yet.

The light is powered by two AA batteries which are heavy. The batteries fit in to a small battery case which has two wires with stripped ends. The wire from the light also has stripped ends so the idea here of course is either to solder them together or fit a small switch. The battery pack could be used to help balance the Tutor.

Mike

[Tim Cheal]

Hi Mike

Thanks for the updates and great info. I am following on behind slowly.

I thought I would provide an update on my progress so far, which is slow but steady. I could not get my head around the main spats and how the axle fitted inside, so I reverted to a little bit of butchery and but the spat so I could fit the axle from below. I still have no idea how I was supposed to do this, and end up with a nut inside the spat as illustrated.

I have modified the tank mount, using some cup hooks and an elastic band.

And, I didn't like the way both pilots were Russian and looking up (as if starting a loop), so I "dremelled" the markings off the helmet and decapitated one poor gentleman to put his head back on in a more pleasing manner.

They are not fitted yet, but this is the impression:

I decided on the ASP 91 as it is only 10 grammes heavier than the 80, but haven't got to the point where I can assess the CofG yet.

I have started to fettle the cowl, and I agree that the bit that tells you how far on the cowl goes is sort of missing. Common sense has prevailed (I hope!!).

Tim

[MikeS]

Tim looking good so far. I think you right about the 91. Now I have nearly got it finished it is still tail heavy. The 70 might be on the light side.

In hindsight I should have posted how I put the front axel and spat together.

I did scratch my head a little but came up with this.

1 Remove the hex bolt from the oleo so the wheel axle unit is free. The hex bolt washer has a small locking pin which you can use later.

2 slide the axle unit in to the spat and line it up with the hole at the top of the spat and make sure the unit it is square to the spat.

3 Screw the hex bolt, washer and locking pin through the axle unit and spat and in to the sprung oleo part. Then remove the screw, washer, locking pin and axle unit. You will have a small hole indented in to the top of the spat from the locking pin.

4 Drill the small hole through and then rebuild as above making sure the locking pin comes through the spat and in to the hole in big washer on the bottom of sprung oleo.

5 For the next step I used the flash on my phone as a torch and sat the hole assembled unit over the phone. You can use a torch or lamp. With the inside of the spat lit up you can see the holes for the axle inside. I marked the outside of the spat then drilled through both sides. 6 Slide the axle through the hole in the spat and axle unit. Then the first collet followed by the wheel and finally the second collet. I used a pair of thin fishing pliers for this. You will need to cut down the axle so mark it now and then remove. Cut off at the marks and refit as above with locktite. Mike

Edited By MikeS on 19/08/2013 01:04:59

Edited By MikeS on 19/08/2013 16:05:34

[MikeS]

Well got the CofG in the right position by using the light battery pack. I attached it to the front firewall.

With everything done apart from the cowl I took it down to the club.

Everything looked good and with the engine running well I did some taxi runs up and down the strip.

I felt it was ready so taxed it round and opened the taps. It went off like a scalded cat. Pulled back on the stick and it slowly climbed off the strip.

Once at height I trimmed it out over a few runs. Another club mate came over and watched. I put it through a few stalls and it either slowly dropped a wing or just slowly dropped its nose but I had to fly slow to get it to stall.

Then I did a few approaches and go a rounds. On the second attempt a call was made that something was hanging off the model so the second approach became a landing.

I landed short and on retrieving the Tutor I found the right wheel axle nut missing and the spat and wheel (now back in to position from the landing) was what was hanging down.

So a good maiden with a few a few minor things to do.

Mike

[Nev Haycox]

Well done Mike, glad all went well. Looking forward to starting mine now, the plan is to electrify it.

Nev.

[Terry Walters]

Nice one Mike - I have one of these in the 'queue' to do too. Bought it from the same place as you bought yours - excellent value and couldn't resist it..

Your build blog has been very helpful for when I get round to it so thanks for that.

When you said it climbed slowly off the strip - did you mean that you, correctly, allowed it to gather flying speed whilst in ground effect or that it was itself a little reluctant to climb?

Terry

[David Ashby - Moderator]

Nice one Mike, well done

Good models normally need a few tweaks after the first flight, it's when there's nothing to do that I start to worry

[Paul Marsh]

Mine flew well, even with a 50 two stroke. Was thinking of a 4 stroke, but like the Turbo Porter,the full size more has a whine than a rasp of a four stroke.

Mine didn't need lead,but it does seem quite heavy, although flys ok.

[Tim Cheal]

Well done Mike.

I will be a couple of weeks behind you.

Thanks for the help with the spats, it was the main wheels that I couldn't get my head around.

I also wish I had looked at your pictures a little closer as I had installed the engine on the wrong side of the mount meaning the engine was off centre. I didn't realise until the cowl was nearly fitted, but I think I will get away with it!

A schoolboy error I think! But it is something to watch out for if anyone is still to mount the engine!

I shall double check my spats (I had the same happen on the early flights of a model a few months ago!)

Tim

[MikeS]

Posted by Terry Walters on 20/08/2013 07:05:46:.

When you said it climbed slowly off the strip - did you mean that you, correctly, allowed it to gather flying speed whilst in ground effect or that it was itself a little reluctant to climb?

Hi Terry.

Being the first time I had flown it I let run down the pitch a little longer than I felt I needed to. On pulling back the stick I felt it didnt want to unstick. When it did unstick it slowly lifted off. My feeling is that it needed a little more elevator than I had set on the low rates.

I have set the rates on DX8 to three positions 50/75&100% movement. I was using 50% at the time of the maiden so will try 75% next and rework the settings if things improve.

Mike

[MikeS]

Posted by Tim Cheal on 20/08/2013 18:10:33:

.

Thanks for the help with the spats, it was the main wheels that I couldn't get my head around.

 

Just in case anyone building this needs some pointers here is how I did the main wheels. This might not be 100% right but it worked for me.

In the manual it asks you build the rear axle as follows:

1. Slide the plywood brace block, washer followed by nut, the wheel and finally the last collet. The idea is the plywood brace block is glued in place in the spat. This adds strength to the fibreglass spat. The small round plywood washer glues in place on the other side of the spat for the axle to rest in and hold the spat from moving

2. Of course all of this has to fit inside the spat but there is not enough room to fit the second collet.

So I did a work-a-round.

3. Hold the spat against the undercarriage leg in the correct position. Mark though the axle hole in the U/C leg so you have a drill mark on the spat.

4. Match the drill bit to the size of the axle and drill though the spat where you marked.

5. You have to cut down the axle and there are two ways to do this. The Quick method or the scale method.

Quick method

You can drill both sides of the spat and slide the axle all the way through and cut down the axle to size so the axle is level with the spat. Then refer to note 1 remembering to slide the axle through the spat first.

Scale method

As above but do not drill both sides only the side the axle will pass though the U/C leg. Measure the axle and the gap in the spat remembering to allow the axle to almost touch the other side of the spat. Once cut build as above referring to note 1.

Build the the assembly without the wheel but put on the round plywood washer and mark where the round plywood washer touches the other side of the spat and mark the spat with a pen. Disassemble and glue in place the round plywood washer and if you have not glue the plywood brace block as well.

Once dry rebuild, but remember to use locktite on the thread on the axle. once the unit is assembled it bolts on to the U/C leg held on by a washer and nut again use locktite on the nut and also the grob screw in the collet to keep the wheel in place.

Mike

 

 

Edited By MikeS on 22/08/2013 15:49:12

[MikeS]

Well here are some phots from the big day:

Pre flight checks and final adjusting.

I had to fettle with the fuel tack for ten minutes or so but it was all good and the engine ran well

After the maiden and the shakes had worn off lol.

I normally like to try out the stall with and without flaps. However due a strange servo problem I was unable to use the flaps and disconectted the servos. For some reason both servos kept fluttering when sitting idle. We tried them in a differnet channel and they still did the same. I have two more that I brought when I brought these I will try them and may have to return to the shop.

Mike

[Terry Walters]

Hi Mike,

Thanks for that all makes sense now. It'll be a while before I get round to it - or maybe not.......looks very nice doesn't it?

Well done to Jess!

Terry

[MikeS]

Terry.

Glad to help.

The Tutor is a nice looking plane. Its looks fall you as you think those thin wings and weight of the model will make the model a handful.

However it flew very well and little fast but that was more my fault as I wanted to trim it out and test the stall before slowing it down.

Thanks Jess did well and is happy with her results.

Mike

[MikeS]

Put the cowl on today. It took a bit of working out to see where the cowl should go but using the front of the engine washer as a guide I marked the locations of the cylinder head, exhaust, mixture screw and cowl securing screws.

Now I am using a ASP 70 four stoke and it just fits with the back end nearly touching the firewall but I used the plywood firewall as an anchor point for the securing screws as I good not see any blocks etc in side the fuse. I think you are supposed to have four screws but in my kit their was three. I also used the suppled locking washings as well.

I was going to order a right angled exhaust port but in the end I decided to exit the exhaust outside the cowl. I felt that there would too much heat in side the cowl from the exhaust sitting at the back of the engine if it was hidden in there and it might affect the cooling of the engine.

I went with a deflector as the exhaust exit would be in line with the wing.

Location of the mixture screw and top securing screw. The front of the engine drive washer should be 110mm from the firewall with the top screw located in the middle of the firewall it measures 23mm to the back edge of the cowl. The other two screws are in the bottom around the sides.

Mike

Edited By MikeS on 26/08/2013 13:33:28

[Tim Cheal]

That is looking really good Mike.

Mine is getting close. Servos and control runs set up today. I found the rudder control wire was binding quite a lot with the fuselage where it exits, so I put a little bend in this to give it a bit more room where it exits. Otherwise I managed to route the nose wheel and throttle runs either side of the tank with no issues. I need to see where the CofG is next before I know where to put the battery pack to hopefully eliminate any additional balance weight(s) being needed.

With my ASP 91 I opted for the 150 degree knuckle from Just Engines which then allows the exhaust to sit in the recess on the starboard side. It does mean you have to lose a lot of the cowl though (pictures tomorrow).

For the record I had to reduce my rudder horn significantly so it doesn't foul the elevator, but with that reduced I do now have plenty of rudder throw with no binding or catching (I could see me getting it all jammed up on a spin exit!)

I have used standard servos for the flaps (HS311) through a Y extension lead, so I have used the alternative mount for the flap horn as David describes in his review in RCMandE. I have found the review most interesting, and extremely helpful, so thank you David. Seagull must have read it to as I had 2 extra wheel colletts included with my kit (but didn't use them!).

One question if I may. I have damaged too many models by the undercarriage mounts giving way on landings (I fly off a grass site which has been rutted in the past by motorbikes, so can have the odd unexpected 'divet'!). I was thinking of mounting the undercarriage legs with 4 mm nylon bolts instead of the cap head steal bolts supplied. Do you think this will work?

Tim

[MikeS]

Tim. I also found the control rods bind a little on the elevator and rudder. I may revist them and make sime adjustments. I think nylon bolts would work well for U/C leg mounts.

It sounds like your getting well with the Tutor TIm, I expect that your maiden is around the corner.

Mike

[Tim Cheal]

Hi Mike

I simply cant get my photos to upload (I have tried the cache clear as mentioned in another post, but I still cant get more than about 1% every 10 seconds on a single 4mb picture, speed test indicates all is fine with a 12mb download speed an 0.28mb/sec upload speed). I tried last evening and now tonight, but I need to wait until the site is fixed.

Tim

[Terry Walters]

Hi Tim - i always reduce the size of my pictures files to 25% of the original before trying to upload and that works fine. Give it a go and see what happens - it maybe that your files are too large?

Terry

[Pete B]

As Terry says, you need to resize your pictures - I'm on a slow by modern standards connection and I find pics resized to 1200x800 pixels upload and reproduce adequately. Try no more than 3 at a time, as it can 'time out'.

Pete

[Tim Cheal]

You were right, smaller picture uploaded OK.

So, here is the engine with the 150 degree knuckle.

The bend I made in the rudder control rod to ease up the movement.

And the rudder horn (significantly shortened so it doesn't foul the elevator).

I found that having assembled the nose leg I had not aligned the flat with the correct position of the securing nut for the steering arm, so I had to create another flat with the trusty Dremel copy that I have!

I have still some work to do inside, so the canopy is just resting on the fuselage int he picture below.

Regards

Tim

[Biggles' Elder Brother - Moderator]

Hi Tim,

I've often found a bit of a problem keeping these various exhaust knuckles fully tight - have you experienced any issues?

BEB

PS Nice installation by the way!

[MikeS]

Tim I do like how you have installed the control rod on the rear. Looks neat.

Took the Tutor out yesterday and had a few flights with it. Did a greaser of a landing on the first. The second landing was a little questionable and the third well all I can see is see for yourself.

 

Its a clean break right at the glue joints. To be honest little glue was used by the factory. Well it has all been put back together and the glue joints have been beefed up a little.

The landing was pretty good, the rear wheel had just touched when it bounced about two feet in the air, the right wing rolled a little then the right wheel caught and it nosed in.

Mike

Edited By MikeS on 30/08/2013 20:14:27

[Terry Walters]

Oooooh! Sorry about that Mike! Glad to know it's already fixed but I might well beef mine up from the start - although these ARTFs are sold for both IC and 'leecy' it is usually obvious the weight has been kept down to accommodate the needs of the 'leccy' set up. This makes me feel a little insecure when an IC engine is bolted onto the firewall instead of a leccy motor.

I still won't be starting mine for a while yet as I have other stuff to do first but 'if there were enough hours in the day' I wouldn't be able to resist it!

Keep it up Mike!

Terry