Tipsy Nipper

Weight & balance also MWTO. Used to be confused now not so sure, there seem to be conflicting numbers here. I have the original (grubby) owners manual and various other items which tell different stories. Can someone please set me right. 1 original manual June 1967 page II.8and 9 says MTOW 300 (aeros.) and 330 (nonaero) CofG aft of datum 365---420mm.
2 Nipper kits & components leaflet MTOW 750 & 685 lbs ( 341 & 311 kg )
3 from a wt & balance form blank dated 19/9/92 MTOW 300 &330 with CofG aft of datum 381---469
A prelim shot at W & B for UDT with its 1835 VW 2 batts 2 coils 2 waste spark systems a large oil cooler and hyd. brakes come out as follows :-
"empty" weight 215.56 CofG locations, me + full tank 398.88 mm ---me + "empty" tank 423.55 mm----- no load "empty" aircraft 321.27 mm
I cant see that the "empty" CofG pos is critical except where it impinges on differing pilot loads.
The saga of tailplane rubber washers has developed. After fitting the mainplane I noticed that the tailplane was noticably left side down. Adjustment of bolt tensions had no effect. Finally realised that the fuse bracket was canted ( rudder is plumb) and checking thro the scrap found the original rubber bracket pack and it was TAPERED !! So I made a tapered ply pack for under the new rubber and included rubber washers OVER the struts-- one of 5mm and other of 1mm. Now level and a good fit but a few mm higher so had to do the incidence AGAIN ! Getting there but expect difficulties with the admin. Jantar

Hi Jantar

The MTOW here in the UK was 330kg (non aero) 300kg (aero) per the owners manual but if we applied to the LAA this was increased to 340kg and 311kg (748 & 685lbs). I think this MTOW increase was introduced by Slingsby when they built the Mk111b Nipper.
As to the empty weight CG. You need this to calculate the CG when the aeroplane is loaded (fuel + pilot). The moment arm points are all measured from the datum (leading edge at the root) including the empty CG position. Refer to the Nipper manual page II.8 paras 2.4.5 to 2.4.10. Don't forget that for the 'empty weight' the tank should contain 1.3galls of fuel and when weighing the aeroplane the top longerons in the cockpit should be level.
With regards to the bracket, would it not be best to make and fit a new one, a bit of work I know or is the fuselage already covered. I hope the top longerons are not twisted!!

Hope this helps, it reminds me of the 'fun' I had building my Nipper.
Keep up the good work you WILL get there in the end.......honest

Stuart