couple more TM questions ;-) - RC Groups
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Dec 28, 2001, 05:10 AM
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AussieParkflyer's Avatar

couple more TM questions ;-)

Ok I've purchased a few goodies for my TM.
I got 6 cadnica 250mah cells today and succesfully soldered them together into a pack that fits neatly into the tiger moth batt bay.

Should I have bought 7 cells?

Also I found the neatest looking 50mm wheels that seemed really light to me in the shop!
I got home and they weigh 14gms each. Thats a whole ounce for the pair ((

Is there ANY chance that the TM will carry this extra weight?

Also they had spare motor packs for sale but I didn't know which one suited my tiger moth.
They were GWS IPS something a or b?
They were different ratios of gears I think.
1:7 was one I think and maybe 5.8:1.
Any suggestions?

Also I tried a different size prop than the stock 9 x 4.7
As the only spares the LHS carry were 10 x 4.7

It seemed to have a lot more authority in the air until i broke the plastic gearbox cage and came home

Waht other sizes are possible?
I have heard 9 x 7 which seems a big change in pitch over the stock prop.What difference in practical terms does the pitch make?

Thanks heaps
I know you guys are gonna enjoy answering my questions?;-)
All help is appreciated and will be returned when I get some more experience.
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Dec 28, 2001, 08:59 AM
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aussie slowman's Avatar
G'Day Pete -- the 6 cells will be fine -- but an extra one will give you some more oomph!
The 10X4.7 will give you better thrust but a lower airspeed-- I ran a 10X8 this morning and it just hummed along -- great climb rate-- but might be a little harsh on the motor..
the TM should handle an extra ounce but it will be sluggish and might need that extra cell?
the 9X7 are good -- the pitch increases the amp draw when throttling up but unloads as airspeed rises they are more efficient at higher speeds-- provided you overcome the drag of the airframe --put very roughly higher pitch more airspeed==bigger diameter more thrust at lower RPMs
Regards to motors make sure you get the GWS IPS DX-A
A is the gear ratio -- A's come Std with the moth -DX denotes the gearbox is of the ball bearing type-STD boxes are plain bronze bushings and much less efficient-- look at the endbell ( the arse of the motor) the black ones are the wiper brushed models -- grey ones are carbon brushed-- The different gearboxes allow the use of different prop sizes -- the motors such as IPSDX-B/C?D?E?F are higher ratios which let you fit bigger props for more thrust at lower RPM (same motor revs but) More useful for indoors where you need more OOOMPH ,less speed as far as what the shop carries in spares -- if you stick with the 9" range they are gonna sell you a lot lol so its in their interest to stock up for you -- they come in six packs to the shop so it isnt a great investment for them to get them in for you
The 10 X 4.7's should be fine however
I read that the 8X6 gives good speed -- gonna try it out in the near future
Dec 28, 2001, 10:09 AM
an earth bound misfit, I
Basketcase's Avatar
Hi AP, you want to try the 300mah NiMH batteries, good power/duration/weight. Use either 7 or 8 cells.

With my moth the best all around prop seems to be the 9x7.

I've tried several different wheels and a thicker wire landing gear. The heaviest wheels were Trexler #6, 63mm, 6 gr ea. I've also tried HL Lyt 2 3/8" 67mm, 5.8 gr ea. Two of these tires and the wire weigh 17 grams, about 10 gr more than stock. The moth still flys okay but they do make a noticable difference.

I was trying to get reliable ROG from grass by using the big tires and found the best wheels for that were litestik wheels. They don't look too good so I finally settled on the stock wire and Hobby Lobby Lyt 1 11/16 43mm, 2.7 gr ea. These will land on grass pretty well, and ROG from dirt or hard surfaces very well. I also added a homemade steerable tailwheel which makes it taxi like an RC car.

For pics of my moth with the different tires check out my site