Mini Super from plans

[Jeffrey Cottrell 2]

Hi Guys

I'm building a Mini Super (75% Super 60) from a plan I downloaded from Outerzone.
Obviously no build instructions, and I'm a bit confused by the front end.
The plans call for 3/16 infill between the longerons and uprights on the first 4 bays.and a 3/32 doubler from the back of the cabin to about half way down the tail.
That's all ok, but then it says 1/16 internal doublers, with no info as to what material or what extent.
Mine is going electric, so I think 1/16" ply would be overkill. I have 1/16" balsa or some offcuts of wing skinning veneer in my scrap box.
I picked up on a 2012 thread from Nev about his build where he did not use the 3/16 infill but made up 1/32" ply doublers instead.

So, guys, what's your thoughts?

Jeff

[flying pastor]

Jeff, having built this exact model many years ago there should be an arrow downwards from where it says 1.5mm doubler to the rectangular plate that supports the undercarriage dowels. It is a small ply plate that has the words 3/16 dowels written on it. The plates are there to strengthen the infill and to stop the dowels pulling through the soft infill sections. So just two small ply plates, one each side.

All the best...Chris.

[kc]

If the model is just for electric then perhaps leave out the engine bearers and use 1/32 ply doublers and a liteply battery platform instead. Moving the engine bulkhead slightly forward to allow for the reduced length of the electric motor would seem worthwhile.

[Jeffrey Cottrell 2]

Hi Guys, thanks

Chris

Now you've pointed it out I can see the outline of the u/c doubler. However there is nothing to link that to the text.

Something else learned.

KC

Yet to decide what motor to use, so I'm building as per plan. Once I decide I will build a box to fit to the front bulkhead to move the motor forwards by the required amount.

This is a scrap box build, and I don't have any 1/32 ply available. Choice between 1/16" balsa, grain vertical, or wing veneer.

Ho hum

Jeff

[kc]

Building a box to fit the motor on usually means the battery cannot go as far forward as the motor, then getting the CG right means using lots of lead. Moving the bulkhead forward means the battery can go immediately behind the motor avoiding the lead and in this case also means the hatch could be further forward too giving better access to the battery.

Ply is only layers of veneer, so two layers of veneer with grain at right angles would make reasonable ply

[Jeffrey Cottrell 2]

Hi kc. Good thoughts, thanks.

First of all, the batteries I intend using are these. They are only 28mm wide and 20mm deep, so perfectly possible to cut a hole in the former to allow the LiPo to slide inside the motor box, thus providing support for the front attached to the strongest part of the structure.

Since Chris pointed out that the note on the plan about internal doublers only referred to those to re-inforce the u/c mount seems the rest of the nose does not need doublers at all.

If that's good enough for an ic model, should be fine for electric.

Anyway, my intention at the moment is to complete the fuz sides. Gives me the opportunity to look at things in '3d' and get a better idea of how to layout other components.

On with the build

Cheers

Jeff

[kc]

Jeff, do you think that those 1250 mah Lipos will be enough? Most people use 2200 mah 3S in 48 inch span / 4 pound weight models and even then flight times are not long - typically 6 minutes depending on flying style. 1250 mah might give 3 minutes at full power depending on motor and prop etc and flying style.

If you cut F2 away so that a 2200 mah Lipo can fit through it it would be better. My 2200 are 25 to 30mm by 35mm getting a little puffed out when used hard for a time, so that's the minimum space I would recommend. F3 should also have a lipo size hole to allow the lip to fit further back if required.

Unless you intend to revert to ic power at some time the engine bearers are not really needed. A liteply battery tray and ply or veneer doublers would provide enough strength instead. Saving all the fiddly square holes in F2 and F3 and giving maximum space for the Lipo plus wires, plugs etc.

Note that the wing dowel hole needs ply reinforcement ( its unnoticeable below the windscreen and longeron )

Anyway that's just my idea of how I would build this model ( it's on my list .......) but it's your model!

[kc]

A further consideration is the electric motor type - some have the shaft at front and the backplate at back while others - such as 4Max- have it the other way round and the shaft sticks out thro the backplate. 4 Max type could be fitted to a strengthened nose ring if ply and securely fastened to the bearers. That could leave the whole top behind nosering as a hatch if F2 was cut away at top.

[Guest]

Here are the details of the modification I just completed about 3 weeks ago.

This is a KK Mini Super that has been converted from 0.09 cu in Glow. This is my first conversion

The KK version is tricycle undercarrage and a wider body by about 3/4 to1 inch

It is still waiting to maiden - I visited NLMFC three weeks ago but I was using a 2S pack and I didnt have enough umph on the 10 X 6 prop to get over the drag of the grass.

Also the fact that I'd moved the throttle trim to minimum while carrying it to the strip meant I wasnt getting optimum power at take off which probably would have made the difference.

Anyway Its now got 2200 3S lipo on a 9X5 E prop pulling about 220 Watts on a fully charged pack which feels more than enough. All up weight is 2 1/2 lb

My motor is an overlander Thumper 2830/09 (210 Watt) I think the 2836/08 would possibly have been a better choice as it has more margin at 270W. Its also got the 20Amp ESC.

As my model was already constructed and I was doing major surgery to the nose.... I chose to make a ply mount utilising the existing structure. The self taping screws on the motor in the picture are swapped for caphead screws and nylock nuts now.

With the 2200 3S lipo I am now slightly nose heavy and need to take a little lead out of the nose. I added 50g to reach optimum balance on the 2S pack.

[kc]

Nigel, very nice model & that is remarkably light at 2 & 1/2 pounds all up weight. The Lipo seems further back than i expected too. Must be that built up structure at the tail that accounts for it. Presumably F2 takes the nosewheel and is therefore needed there.

[Jeffrey Cottrell 2]

Hi Guys

Kc, couple of thoughts

First of all, if this model turns out at 4lb, I will be handing in my balsa knife.
Just finished work on a KeilKraft Gaucho. Ok, different style model but same span, built up wing and tail and all sheet fuz, thinner but longer than the Mini Super.
That came out at 13.4oz ready to rock.
I can get an easy 7 mins on the converted slope soarer I use the 1250's on. Don't think duration will be an issue.
However, it might be worth while making the hole in the bulkhead big enough to accommodate 2200 packs, for possible futureproofing.
I notice all HK warehouses are out of stock of the 1250. Hope they will be restocking, but if they don't I might be forced to change.
Take your point about 4-Max motors. but they do come with a front mounted prop driver, so it wouldn't be much work to cut of the protruding rear shaft, and bulkhead mount as usual.

Nigel
That's a pretty model you have there, and a neat conversion to lecky.
My plan shows a tail dragger u/c which I plan to convert to tricycle.
Could you let me know how wide your fuz is?
My plan says designed by Ernie Webster and developed by David Boddington, so I don't know which version I have.
2 1/2 lb all up sounds much nearer the mark, though I would be aiming for less than that.
Looking at the model, with all its ic fittings still in place, rather concerned you needed lead in the nose. Can't see from the pictures, but where is your LiPo mounted?I
Found the Thumper 2830/09 on Overlander site, but not the 08. Have they been discontinued?
Final thought.
An 1800 4s is only slightly deeper than the 2200 3s. You could drop the prop down to an 8 x 4, slide a 4s in there and really scare the horses.

May be an idea?

Jeff

[kc]

Jeff, glad to see that you can build lighter than the average modeller.

David Boddington explained the the Mini Super was a reduced version of Ernie Websters Super Sixty hence the credit. The article in AMI goes on to say Keil Kraft accepted Boddos reduced plan and paid him 15 shillings but redesigned it with wider fuselage and tricycle u/c. Boddo said the AMI plan ( Outerzone one at the moment) is the original form taken from the original tracings but the elevator extension is shown.

The article states the wingspan as 45 inches, but the plan states 48 inch while the free pull out plan from AMI Nov96 actually measures 46.875 inches with 3.125inch fuselage. Did the printed Outerzone plan measure the same? ( span includes centre section of course so each wing half is 21.875 inch )

[Jeffrey Cottrell 2]

Hi kc

Thanks for that, good to know.

My wing panels measure 21.75" each, and the centre panel is 3.125" giving a total span of 46.625". Given the plan shows tail dragger u/c and the elevator extension, looks like I have the original AMI plan.

Good news.

Wonder why KK decided to widen the fuz. Only thing I can think of is to give a more solid base for an ally u/c.

Ho hum.

Jeff

[Jeffrey Cottrell 2]

Posted by kc on 20/07/2020 16:55:58:

Jeff, glad to see that you can build lighter than the average modeller.

Hi kc

Trick is to use an airtight covering, then pump the model full of Helium. Works a treat but makes your voice sound funny

Final word on batteries.

Definitely going to make the hole in the bulkhead wide enough to accept a 2200 3s, but also a little deeper so I can try an 1800 4s.

eCalc says 857g static thrust at 12a draw. Liking those figures

Jeff

[Guest]

Thanks for the kind remarks about the appearance of my mini super it exceeded my expection but with furlough time the refurbishment and covering was not rushed.

This is Hobby King polyester red with a little HobbyKing white and OraTrim black . Its the first time I've used HK stuff its quite good and will take curves easily with heat. My only gripe is that the backing is white and it shows at the edges especially against the red. Meths seems to remove some of the excess if you get some shrink back but there is always a hairline witness. £9 for 5 metre is very reasonable compared to pro film 2m price.

KC explained the KK one was adopted from the Boddo one which was scaled down from Ernie Websters original Super60.

The fuselage of the KK one is 3 3/4" wide from nose to trailing edge of wing. It then tapers to 1" wide at the rear where the escapement would have actuated the rudder by torque rod. The KK elevator is two piece one each side of the fuselage joined by 3/16" dowel within the tail seat.

I expect it was widened to make single channel gear easier to install especially as this is a trainer and bought by beginners.

If you plan on widening then remember to widen the centre panel accordingly. KK also changed the wing design a little it has a moulded leading edge which is a little larger than 3/8" tall and was hollowed

The main wheels dural front edge is inline with the 3/16" upright behind the first side window.

F2 is the location of the nose wheel and it is not steerable.

My Lipo is up against F2 and just finishes behind the front wing dowel. It is set in a box/tray at -30 degees which will give enough space for a 4S if I wanted (two of the original 2S packs in series) but my ESC states 2-3S lipo.

Because of old damaged structure on my original I duplicated the 1/16" balsa inner lower stiffeners similarly on the upper longron's as those had had the rubber bands through them in a meeting of plane/tree/fence some time in its previous life. Fresh wood was also scarfed in to the top longrons and wing seat..

The larger Overlander motor I mentioned is available It's the 2836/08 270W motor and its on page 2 of the motors on overlander site. See the link

link to Overlander 2836/08

But with the 2830 motor I installed and 3S with 9x5 I'm peaking at 22 amps and around 220-30 Watts fresh charge and it drops to 180W at about 3/4 throttle static so I'm sure its going to be ok.

Earlier I fell foul of beginner electrics looking at the motor spec and forgetting V x A = WATTS Doh! so 7.4V x 20amp = 148W hence wheezy take off run.

Nige

Nige

[kc]

I will be interesting to know if Nigels model flys well with the tiny elevator and small rudder ( even if the trim tab area is used for rudder ) assuming they are the same size as the AMI /Outerzone plan.

It took me a while to work out what the hole in the tailplane TE was for - looks like the hole takes the rubber band for banded on tailplane. People now don't like banded on tails on RC vintage models due to variations in elevator trim, so again it will be interesting to know if Nigel's model has this and it works well.

[Guest]

Well I can only say that it used to fly well on its 09 Glow. Rudder response was a little sluggish in strong wind when trying to turn up wind from cross wind leg.

In the refurb I enlarged the KK one. Basically the original rudder post was where boddo had it but it was beefed to 3/8 or 1/2 inch width. The rudder was the Tab and the Rudder shown on Boddo plan joined as one.

So in this Refurbishment I moved the rudder post the width of the existing stock into the fin and added that to the rudder to gain 30-50% more area. I expect it will now be fine.

The Elevator is as the Original KK kit shown in the underside photo.

Below for more detail.

Nigel

[kc]

The increased rudder seems a good idea for 3 channel RC.

That elevator looks as though it may be bigger than the AMI/Outerzone plan which measures 3/4 inch at middle tapering to 1/2 inch at tip.

[Jeffrey Cottrell 2]

Hi kc

Agreed, that definitely looks wider. Also looks like the tailplane trailing edge has been moved forward a bit.
On the plan the tail te is shown as level with the fuz end, and the elevator (text says 1/16"ply) would extend beyond the end of the fuz.
The elevator is shown as one piece, where Nigel's has a centre joiner.
Maybe a bit of 'on the fly' redesigning as called for.
I generally use the TLAR system.

Jeff

[kc]

Have you considered a one piece elevator with a glued on tailplane instead of rubber bands? Saves the weight of piano wire joiner, rubber bands and dowels. And could also have the elevator pushrod right down the fuselage centre for simple positve control. No elevator trim changes due to change of alignment caused by rubber band fixing.

[Guest]

I have a 3/16" sheet insert added to the top of the tailplane that locates it inside the fuselage. That enables the rubber banded tail and maintains the elevator trim.

I did consider adding the elevator horn in the centre and having the pushrod completely inside but it seemed more effort to do for a refurbishment that was necessary. This is a modification that I did do to my KK Elmira back in 2006.

If you do that and bond the tail on .... and the elevator clevis/actuator needs maintenance it would require surgery.

Hence the pushrod on mine comes out the side

[Jeffrey Cottrell 2]

Hi Guys

Going with the banded on tail. More in keeping with the rest of the model, but I like the idea of a locating plate inside the fuz. Thanks for that, Nigel. Hope you don't mind if I pinch it.
On your re-furb, did you increase the size of the elevator?
Looking at my plan, seems the elevator is an afterthought. Very narrow and made of 1/16" ply.
Guess this was designed for bang/bang operation, so too big would give issues.
Anyway, thinking of reducing the te width to 3/8" rather than 3/4" and adding that to the elevator width.
Leaves the back edge slightly forward of the fuz end, but if I sand the bottom edge of the tail post up at an angle, can still use a one piece elevator and a central horn
That's my current thinking anyway. Expect it to be changed several times before I come to a final design.

Cheers

Jeff

[Guest]

Hi Jeff,

Please feel free to pinch the idea to locate the tail. I applaud your decision to use bands its more vintage

To help you out I've measured the key dimensions from my tailplane not bothered with the span I think it will be same as the Boddo version if not just add the addional width of the fuselage from earlier.

Here is a scan of a sketch in old fashioned imperial units.

Nige

[Guest]

oops... missed from leading edge to rear of fixed tailplane which is 4 5/8"

Nige

[Jeffrey Cottrell 2]

Hi Nigel

Thanks for that, very helpful.

I notice you have the chord of your tailplane at 4 5/8", which explains the gap between the te and fuz end in your picture.

My plan has this chord at 5 1/2" to the fixed te, which fits the fuz opening. If I trim the te down from 3/4" to 3/8" this gives an elevator width of 1 1/8". almost the same as yours.

I see a plan forming.

Jeff