Retlas Spitfire V Instructions

[leccyflyer]

A pal has given me a lovely Spitfire Mk V kit, by Retlas, which has been started, but needs completion, The fibreglass fuselage moulding is truly a thing of beauty. Unfortunately the kit comes with no instructions, though there is a small sketch plane showing the veneered foam wing parts, spars and balsa control surfaces and wingtips. The 69" span wings are joined, with a bit of veneer cracking to be repaired, but are in reasonable shape.

 

The kit is long since discontinued and Retlas no longer exists - I believe that Unitracts International, the retracts people, took over distribution of  the kit for a while, but they don't appear to be around any more.

 

If anyone has a copy of the instructions for the model, that they would be willing to scan, or photograph that would be most appreciated.

 

Many thanks

 

Brian

[GrumpyGnome]

I'm afraid I can't help with the manual, but there is a thread on rcuniverse that may be of interest... https://www.rcuniverse.com/forum/kit-building-121/3211209-c-g-point-my-retlas-spitfire.html

[leccyflyer]

Thanks GG - I found that page when looking yesterday evening, which has good information on the CG and the likelihood of having to add nose weight. I'm anticipating a 10 cell set up, so hopefully there won't be too much dead weight.

[Jon H]

I wouldnt be too concerned about dead weight. Added ballast isnt dead as it keeps the model in balance and allows it to fly. I know we do not want to add weight to a model needlessly, but when needs must it just has to go in. I work on the basis that up to 10% of the final weight of the model as ballast is perfectly acceptable, especially in a warbird. In the case of a 70 inch Spit i would expect it to weight around 12-14lbs ready to fly and carry just over 1lb of lead up the front. 

 

These numbers are based on i/c mind you. would the electric setup to weigh more once all of the parts are added up? the motor will weight less for sure but the battery might be more. In any event, if you have done all you can to get weight forward then just add whatever you need to get it balanced and then go flying. As long as the weight is not above what the model and power plant can cope with then it makes no difference how much of it is lead. 

[leccyflyer]

Indeed - I'd never let a model be tail heavy, no matter how much weight it would take to get the CG correct. It's preferable though to have additional battery capacity, rather than lust lead. The e-conversion information is fairly sparse for this one, but back in the days that at least 24 sub-C NiCds were considered viable as a power source, so a fair bit of battery weight there.

[Jon H]

2 minutes ago, leccyflyer said:

24 sub-C NiCds were considered viable as a power

 

the energy density of a lipo would knock those into a cocked hat. 

[leccyflyer]

8 minutes ago, Jon - Laser Engines said:

 

the energy density of a lipo would knock those into a cocked hat. 

Which would mean you could easily carry significantly more amp hours for the same weight, if you wanted to.  🙂

 

I never flew with that many NiCds, my largest pack was 16 cells, still a good 1.2kg of battery, but I've flown some of those 16-22 cell models on 5s1p 5200mah lipos - double the battery capacity at a fraction of the weight.

[Jon H]

1 minute ago, leccyflyer said:

Which would mean you could easily carry significantly more amp hours for the same weight, if you wanted to.  🙂

 

I never flew with that many NiCds, my largest pack was 16 cells, still a good 1.2kg of battery, but I've flown some of those 16-22 cell models on 5s1p 5200mah lipos - double the battery capacity at a fraction of the weight.

 

Yes absolutely and that was the point i was trying to make. Even if the leccy setup was the same weight now as then you would have significantly more power available now even if the model was a little porky.