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Mar 05, 2016, 01:02 PM
Registered User
Thread OP

Pat Tritle/Dumas 35" Tiger Moth power help!

Hi guys, I need some help. I have decided to build a model aeroplane after being inactive for around 20 years or so. I am about halfway through a Dumas/Pat Tritle 35" span Tiger Moth, which I am enjoying, but I am very confused about what to power it with.

When my career got too busy to cart models around with me in the 90s, the GWS indoor stuff was just coming out- I got one of those "stick" things and it was great fun.

The Tiger Moth appears to be from the same era, and the recommendation for it is:

GWS "A" motor and gear drive
GWS 9-7 prop
5A esc
700 or 1320 2-cell LiPo battery

I can't for the life of me find a modern equivalent for all this. The numbers and letters are all greek to me. I was wondering if someone could point me in the right direction- and by "point me in the right direction" I mean "tell me what to order on EBay".

I don't even have a charger. At this point I am better equipped to fly this plane with a giant rubber band.

I just want to fly it around in circles to get used to flying model planes again- I don't want to do aerobatics or anything, so I just need the minimum power- nothing fancy, and hopefully something that fits on the original motor mount as I've already built it onto the plane!

Thanks in advance!
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Mar 05, 2016, 05:22 PM
Obviously I'm a "Minus Member"
buzzltyr's Avatar
By all accounts in various threads here, the Tritle 35" Tiger Moth is a real floater, and very light weight. If you don't mind doing some place besides Ebay, I'd look at a motor like this one:
This motor should have more than enough power on a 2 cell Lipo. As the original used a GWS gearbox, you will need to develop your own firewall/motor mount, because this motor won't mount on the kit's stick mount. I'd also keep in mind that this motor is much lighter than the original GWS brushed motor/gearbox power plant. So you may need to either add nose weight or do a bit of redesign to get the battery as far forward as possible. In any event, I'd think any motor in the 30-50 watt range would do just fine powering the 35" TM.

Mar 07, 2016, 02:01 AM
Registered User
Thread OP
Thanks, Mark- I'll look into that one. I like the idea of a brushless motor, and the one you suggested actually comes with a stick-mount adaptor as well, so maybe with a bit of fiddling I can re-use the original brackets or something.

Thanks for the help.
Mar 08, 2016, 01:24 AM
Registered User
Thread OP
I had kind of assumed this internet forum would be a wealth of knowledge. My thanks to the one guy who answered; maybe could anyone recommend another forum where people know about this kind of stuff?
Mar 08, 2016, 11:14 AM
Registered User
E-Challenged's Avatar
Recommend you start a "build thread" on the Scale Kit and Scratch-Built forum. take pictures as you proceed and get helpful recommendations from those who have previously built the model, including Pat Tritle.

Pat has building tips on his website that may be of help:
Last edited by E-Challenged; Mar 08, 2016 at 11:20 AM.
Mar 08, 2016, 12:06 PM
CA...gimme the CA...
whowhatwhere's Avatar
Originally Posted by Keith Shergold
I had kind of assumed this internet forum would be a wealth of knowledge. My thanks to the one guy who answered; maybe could anyone recommend another forum where people know about this kind of stuff?
That's actually one of the problems a person can encounter here...there is *so* much information posted here, finding something can be daunting! Especially with power system recommendations...geez louise there's a boatload of threads on this topic.

Please excuse me if I'm rehashing something you already know about, but this page has a decent description of the "watts per pound" rule, and how it varies based upon the type of model being built.

HeadsUpRC is pretty good about their motor/battery/prop recommendations. If you look at their motor details they'll often suggest specific planes, or they'll say "this motor is good for sport planes (or scale, or parkflyers, or whatever) between 20-30oz". Plus, their motors typically come with connectors pre-installed, so no soldering.
Mar 08, 2016, 12:12 PM
CA...gimme the CA...
whowhatwhere's Avatar
Originally Posted by buzzltyr
As the original used a GWS gearbox, you will need to develop your own firewall/motor mount, because this motor won't mount on the kit's stick mount.Mark
Heads up sells plastic stick mounting adapters for GWS planes. They're currently out of stock, but should be restocked in a week or two. $! Just make sure you get the correct size.
Mar 08, 2016, 12:24 PM
CA...gimme the CA...
whowhatwhere's Avatar
Couple quick recommendations, based on my own experience. Please excuse me again if I'm overstepping here.

1- Prop balancer. ABSOLUTELY ESSENTIAL. An unbalanced prop will cause all kinds of problems. A balancer is very cheap and worth every penny. I built a stand out of scrap in 5 minutes.

2- Watt meter. Extremely useful when testing motor/prop/battery combinations. It's always good to know whether or not a combo is too much or not enough.
Mar 08, 2016, 01:31 PM
Wayward Pilot
JREEVES's Avatar
I'm just finishing up a GWS Pico TM and using this motor:
with a GWS 9x4.7 slowflyer prop on a 2S lipo it seems to have plenty of poop to fly her 10 ounce AUW around. I need to put it on my watt meter to see what it's drawing yet.
The stick mount is for a 10mm square stick and it has 2mm bullet connectors on it which will work with the Skypower 10 amp ESC they have at HeadsUp. They also sell prop balancers there as well.

EDIT: The EMax 2805-1300kV on 2S 700 30C lipo, max output is 7 amps, 56 watts (voltage sag to 8V), but settles to 6 amps, 48 watts after 15 seconds. This is more than enough power for my Pico TM, which jumped off the ground in 4 feet at 3/4 throttle!

While its a bit heavier than I'd like at 25 grams including the prop saver(35 grams with the 10 amp ESC) its actually the same weight as the IPS-A motor/gearbox combo that Pat Tritle uses with his Moth. You could easily get by with a 8x4.3 SF prop, lower the amp draw and use a 6 or 8 amp ESC to save a few grams and potentially increase flight time.
Last edited by JREEVES; Mar 09, 2016 at 06:05 PM.
Mar 09, 2016, 08:26 AM
circle flyer
slow and low's Avatar
Tritle's Nieuport 35" is a very similar build/plane. If you are unsure of what to do, do as he did. He makes recommendations for geared and brushless. He was going to try the 2808-890 brushless but I don't know how it turned out. That or similar motors in the 50 watt/pound should work fine.
Mar 13, 2016, 09:51 AM
I am just finishing a Dumas Bird Dog. My estimated AUW with battery is 7oz. Pat recommends a MPi EPU4 ,but they are not available so I got a EPU6. The gearing is higher so I may go up on Prop pitch, I can not go to a 10" prop due to ground clearance, but considering the low weight and wing load giving a low stall speed I should be ok trying the 9x4.7 SF on the Maiden? My email is [email protected] . I got the Mpi 280 3.3:1 motor, but its much heavier, and powerful. Alsi I got a brushless Geared from China (no specs). looks about comparable to a Park250 with 4.6:1 gear. I love pat's light designs, and plan on a few more, but I will add ailerons.
Mar 15, 2016, 02:02 AM
Registered User
Thread OP
Thanks for the recommendations and advice guys. I am lost in the woods when it comes to this stuff. I haven't done any model aviation for over a decade, and I have forgotten a lot of the technical stuff, especially the electrical part. I've got a couple of helicopters, but of course selecting a motor and battery for one of those is simply a matter of buying what it says in the instructions.

I sent Mr. Tritle an E-mail asking for advice and he kindly responded right away with a suggestion, so I'm going to go with his suggestion.

I'm mostly finished the frames now, I had a tough time with the laminated outlines until I ordered a bunch of extra wood and was able to select some nice bendy pieces from that. Being able to select what you want rather than using the kit wood (all of which I broke trying over and over to laminate the outlines) makes all of the difference. I'm quite proud of how it's turning out so far. I plan to cover with tissue; I used to be pretty competent at that, so we'll see how much comes back.

One thing the helicopters have taught me is the importance of balancing all the spinny stuff, so I will be getting a prop balancer, thanks for the suggestion.

I'll start a build-thread sometime soon to document all this stuff.

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