ST Discovery Nose Wheel Assembly

[Dave W]

The nose wheel assembly on my ST Discovery seems to have a little slop in it and I want to get in and have a look just in case something is coming loose. It isn't obvious how I can do this and before starting work I thought I had better find out if anyone else has experience of getting into the nose area of the Discovery.

 

It has what looks like a foam cowl that doesn't have too much adhesive joining it to the fuselage. I am hoping that this is indeed just a cover and that the motor and nose wheel leg are mounted to the foam that makes up the rest of the fuselage. If this is the case then I can just remove the cowl and examine the nose wheel leg mounting.

 

If this bit of foam is structural then I think I would prefer to cut out a small section of it, just enough to see what I want and rectify any problems, and then stick this section back.

 

Any help would be greatly appreciated before I start wielding the scalpel.

 

Dave W.

 

 

 

[Tim Mackey]

My mates disco went in a tad hard after he forgot which way the throttle goes

I seem to recall we just pulled the cowl away to reveal the rest and amongst the damage was a broken steering tiller on the noseleg assembly. I was surprised to see the rather weedy looking bell style outrunner within but nonetheless, it hauled the thing around perfectly well, and overall, I was impressed with the model a great flyer.

He has, I believe repaired it all now.

I cant help further, as he is away at sea for 4 weeks on /4 weeks off.

[Dave W]

Many thanks

 

I had hoped it was just a cowl but I didn't want to remove it until I was more certain that I wouldn't be removing the whole front end.

 

I agree with your comments about it being a great flyer - ideal for a beginner like me.

 

Dave W

 

 

 

[Marty Ball]

Hi Dave W, You have probably fixed the problem by now but if it's of any interes to any one else, The cowl is stuck on with double sided tape which will come off with firm persuasion, (When I replaced it I put cross weave tape over the joint because there are loads of ballast wieghts inside the cowl.) take out the 4 scews that hold the motor and you can get at the keep collar and the bell crank screws.

My nose wheel is a little sloppy, I think part of the problem is the weedy size of the push rod, I might beef it up a little as well as uprating the motor as I'm toying (pardon the pun) with the idea of making the model into a gider tug.

[Dave W]

Thanks Martyn. I have been away on holiday so your information isn't too late. I agree with your review of the model (under "ST Discovery (Trainer)"). My only adverse comment about the model is the amount of weight I had to put in the nose to balance it at the specified point. The only convenient place for it was in the battery compartment but now I know how to get into the cowl I can use less weight positioned a bit further forwards.

 

Edited By Dave W on 12/07/2011 15:03:32

[Marty Ball]

I didn't have to add any weight. What size battery have you got in it? I'm using 3 cell 2200 lipo in mine but I have just added a balsa "plank" on the forward side of the battery compartment so The battery now has full lenght contact with the velco. Before, the battery was just touching along the bottom corner and the very top. (if that makes sense?).

[Dave W]

I have the same size battery as you (an Overlander Sport). I made a simple foam wedge to hold it in place rather than use the Velcro.

 

I think different models off the production line could need different weights. I replaced an Easy Star that had quite a lot of nose weight and the new one only needed about half as much. Perhaps the foam varies in density and this determines how much you need..

[Marty Ball]

You're probably right, It's not like they are hi-tech - state of the art models but that said I think the must be right up there with the "best value for money" buys!

[Dave W]

Yes, definitely excellent value for money.

 

[daba]

It's interesting to read all that's been said about weight and Centre of Gravity.

I bought the Discovery as a trainer (my first time flying models), and mine came with a 1800mAh battery pack, not a 1300 as stated in the book.

I actually found the plane to be very "twitchy", the slightest elevator control sending the nose dramatically skywards and causing the plane to stall !!! More about CoG later....

Crash 1 bent the U-shaped motor mount, meaning I had to get the nose-cowl off to repair it - I was unable to get it off without cutting it, but as I needed a new one anyway that didn't bother me. I thought it was a poor idea to have the balance weights glued into the nose like they were, so decided to fix them onto the motor mount bracket (drilled, tapped, and screwed). I was removing weight anyway, because I had got some bigger, heavier, batteries, so need less of them. I was simply setting it up so that the weight seen at the nosewheel was the same as before (thinking that if I kept that constant, I was maintaining the CoG position).

Anyway, a couple of more crashes, and the need for a complete new fuselage, revealed a lot of detail about the inner strength (or lack of !).

First off, the plastic mounting that the aluminium landing gear screws into is not fixed in place very well at all - it simply slots over two vertical plywood plates that are foam-moulded into place during manufature. In fact the only thing holding this plastic mount in place is the silicon sealant between it and the foam ! Not very strong, and the slightest knock (crash 2), can dislodge it and tear it out of the fuselage. There are holes on the plastic mount that look like they should have screws or pins in, and I fixed mine in place by pilot-drilling into the plywood and driving in some pins (picture hook pins !) with a drop of super-glue on them.

Secondly, the nose wheel pivot is a substantial plastic moulding that is brass-bushed, and looks quite strong, which should allow the strut spring to take a fair old knock. Not so !! This plastic moulding is screwed onto a vertical piece of the same flimsy plywood that the main landing gear is attached to. A relatively minor knock on the nosewheel (crash 3) caused the plywood to de-laminate.

New fuselage arrived, complete with original (fixed in place) cowl, so decided against putting the nose weights on the new motor bracket....

Couple all this up with me having added Nav, Beacons, Strobes, and Landing lights (I built a purpose-built circuit for these), I was conscious of where the CoG had got to. (My lighting circuit board was mounted in the "bomb-bay", which puts it on the CoG line, so it wouldn't have affected the CoG position).

The book shows the position of the CoG on the Aileron servo covers, so I built a couple of stands to balance the plane on pins - and I couldn't believe how tail-heavy this plane was with the original battery, and believe it or not, it was near-perfect with the 2800mAh battery which weighs 65g more than the 1800 battery.

So that, I'm convinced, is the reason for the twitchiness and the exaggerated response to elevator control.

I'm just waiting for a bit of calm dry weather to try it out (hmmm, might have to wait a bit, lol)

 

 

Some pictures will be here very soon !!

 

http://www.4shared.com/folder/jhwj9mvp/Outbox.html

 

 

[Tony Read 2]

Hi Daba!

 

I'm very interested to hear how yours flys with your weight.

 

I got the replacement cowl yesterday from Wheelspinmodels (thanks for the blackjacks guys. Haven't had them for years!). So I will be testing it soon. I will NOT be gluing it back on. MB's idea about the tape sounds good to me.

 

I like the model, and I liked the Cessna, but repairing them can be a bit of a nightmare, requiring quite unnecessary butchery.

[daba]

Hi Tony,

 

Wheelspin models is in my home-town, where are you based ?

 

If you're local and want to check your CoG, I have made stands that locate into tiny holes I have put into the aileron servo covers (shows where in the book), you'd be more than welcome to come along and see what your balance is like.

 

You are dead right about the butchery needed to get at anything ! And of course chopping great chunks out of the foam doesn't seem to be a good idea when the foam fuselage is actually the air-frame (structural).

 

I haven't had chance to take the plane up yet, I'm more than likely gonna go along to a local club - hopefully someone will have a Spektrum Tx and will buddy me for my first "real" flight.

 

The 3 I've had already (3 take-offs, 1 landing, 2 crashes) I'm gonna put into the "learning curve" category. If you read my post earlier, those 3 flights were with the supplied 1800 battery, and I now know that makes the plane tail heavy. I estimated the CoG was about 3 inches astern of where it should have been ! The book says not to move it more than 5 mm !! No wonder it was twitchy .... On advice, I've set my CoG slightly forward, I've been told it will make it more stable and sedate, and suitable for a beginner. I can always add weight to the tail later to make it more responsive when I'm more confidant.

[david stracey]

I'm a learner and I've just bought a Discovery on recommendations from members of my club. We fly from a rough grass strip so I've fitted slightly larger wheels. I intend to fit even larger one's when I can find some suitable (Hub 19.00 mm wide and axle 3.00mm diameter). This obviously effects the C of G. The servo covers on my aircraft do not have any markings and the book says the CG Range is only 5mm either way. Can anyone give me a measurement to place it accurately?

[Marty Ball]

I have just sold mine to a new club member who has it as his first model.

I seem to remember the C of G was at the frint of the aileron covers.

[daba]

Yeah, dead right about the location of the CoG - about 5mm back from the front edge of the aileron servo covers. Bottom of page 12 of the manual - Pic. 78

As I said earlier, i popped a 1.5 mm hole at the locations, and built some stands with pins atop to hang the plane on. A pretty simple thing to do.

I just couldn't believe how "tail-heavy" my "standard" Discovery was - even though it came with a larger battery than the quoted 1300mAh Li-Po batter (not a typo - read the manual, page 2..)

Upping my battery size to 2800mAh (65g heavier) brought the CoG much closer to ideal, so you can get a feel for how tail-heavy it really was. I can only put the successful flight (as in take-off, fly around, and land without a crash) as a fluke. That was my first ever RC plane flight, and in retrospect, the twitchiness of the elevator control may not just have been rookie nerves after all.

Since then I have built a "Vanessa CG Machine" (Just Google it, there's loads of links). This has absolutely confirmed the CoG position on my plane to be where it should be, and the design of the machine will allow me to experiment moving the CoG as I get {more} confident flying it. Some decent weather would help !!

The other good thing about the Vanessa machine is that it can be used to check the port/starboard balance as well. My next flight will be with a 2p taped to the starboard wing, about 9 inches from the outer end.

[daba]

An update on where I am with my Discovery.

The coincidence of decent flying conditions and me having the time was made a couple of weeks back (yeah, before all this wet-stuff falling from sky happened).

I can say now that the Discovery handles well in the air, and is very responsive to control. I had replaced the original radio gear with Spektrum, so was able to back-off the elevator travel for my maiden flights. Glad I did, so if you use the ST radio gear, small elevator and aileron movements are needed, don't over-cook it, as the ST radio gear will allow full travel. I've got the feel of the plane now, and have increased travel back to about 80%

I just had to do it though. On only my second flight, I did barrel-rolls and a loop. Actually that gave me a greater understanding of how to control it - so much better than the Phoenix Sim I have used to prepare me for real flight..

As a beginner, I would recommend this plane for a beginner, although she is very "floaty" and will stay up for a heck of a long time on no power, which makes landings hard to judge. Be prepared to "go around" once or twice until you get the hang..

Definately got the flying bug now, wanna go out every day - just a shame the weather is against at the mo....

[Piet Steyn]

Hi

Any comment/ information on replacing an aileron servo on a Discovery? Went in a bit hard and the servo gave the ghost. How does one remove the cover and proceed from, if at all possible.