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Feb 12, 2015, 05:23 PM
Buildn it one stick at a time!
G.F. Beurling's Avatar

Anybody built a downsized Sig Seniorita?

I'm experienced with building kits, bashing, and enlarged plans with planes to 90" and weighing 20lbs.......but I have NO experience with electric at all. For my first electric "park flyer" project, I thought I'd shrink a 63" Sig Seniorita down to 75% to a 4 channel 47.5" plane with ailerons. The actual factory 63" kit weighs 3 3/4 lbs, but I have no clue what a completed 47.5" plane will weigh. I assume I should frame-up the 47.5" plane first and then weigh it near completion to get an idea of what kind of motor I will need.

1)Should I install right thrust and down thrust on the firewall as the factory plans show for a glo plane?
2)In the meantime I'm curious and was wondering if the flying weight ends up at about 3lbs, what kind of motor, battery, servos, and controller would you recommend?
Last edited by G.F. Beurling; Feb 14, 2015 at 11:33 AM. Reason: Corrected grammar so I don't come across like a NYC taxi driver from Uzbekistan.
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Feb 12, 2015, 06:15 PM
B for Bruce
BMatthews's Avatar
If you're looking at a model done with built up strip construction of this sort have you considered some of the old timer free flight models converted to RC?

It's not hard to drop the dihedral down to none or a little and go ailerons if you're after a 4 channel model. And there's many old timer designs that just REEK of character.

Check out the downloadable plans in the old timer's portion of Outerzone for some inspiration before you leap. Just don't be lured in by the scale sections or you'll lose at least a dozen hours sitting in rapture looking at your computer monitor and downloading an entire hard drive of good stuff. YOU HAVE BEEN WARNED! ! ! ! !

The part you want is the I.C. section of free flight sport. Then look for dates and wing sizes that are in your target size.

And if I may? Be sure to check out the Miss Tiny and Comet Golden Eagle. In particular the Comet/Joe Konefes Golden Eagle. It's a fair bit more building but I'll bet you can't resist.

If you decide to stick with the scaled down Seniorita then once you find and scale down the plans I think you'll find that it should not be hard to keep the final weight to closer to 32 oz or even less. When I built the Miss Tiny for SAM 1/2A Texaco it was not hard at all to keep the finished flying weight at 19oz. And that was with slick looking but VERY heavy Kraft smooth hub wheels. The Miss Tiny having a 46 inch span. So even with an extra servo, extra gear leg and wheel and a couple of more inches of wing span I'm pretty sure that with any care at all you'll be at or under 30 oz.

With that in mind you then need to figure out just how sporty a climb rate you want. 45 to 50 watts per lb will offer you a scale like climb that makes the model feel quite trainer like and relaxed. 60 to 70 watts/lb will make it climb at around 40 degrees up at a sporty pace. Anything over 80 watts/lb is jet fighter vertical or near vertical. At 100 or over you're looking at being able to hold it vertical, power up and just release it pointed straight up and it'll power away out of your hand with the right sort of prop. So what sort of category are you after?
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Feb 12, 2015, 07:00 PM
Buildn it one stick at a time!
G.F. Beurling's Avatar
I'm really just wanting a VERY calm and easy park flyer. Believe it or not, I love building and have some really nice large flying models to show off, but I still haven't mastered flyng! Yes, I know I should "join a club and do the buddy box thing". Been there/done that, and I just want to stick with my RealFlight simulator for now (which happens to also have a Seniorita on it), and try park electrics for awhile. I really like the Seniorita, and will enjoy doing another scratch/kit bashing project.

My intent is to buy a Seniorita kit cheap on Ebay and stencil the formers and ribs and make the minimized plans. I can then actually use the balsa supplied in the kit. Having a full kit with instructions and parts to study makes a project go easier too. The 63" Seniorita already uses a lot of light and thin balsa, so I don't tnink any of the wood will be too heavy even for a 47" electric. I will add lightning holes, omit the heavy carved balsa cowl, and do other weight saving measures where I can.
Feb 12, 2015, 07:17 PM
Registered User
I admire what you are attempting to do Randall, but I have to ask why you are making this so difficult on yourself. If you are looking for a plane that is about 75% in size of the Sig seniorita and appropriate for electric power there are many options avIlable to you. Why are you locking into this particular plane?
Feb 12, 2015, 08:00 PM
It's gonna be YUGE!!!
LVsoaring's Avatar
Any particular reason you want to downsize it? Bigger flies better!
Feb 12, 2015, 08:57 PM
team sleprock
whiskykid's Avatar
Randall, I say go for it!

yes you want the right and down thrust, the plane will fly better!

cut the dihedral in 1/2, add your ailerons,

keep it lite, and you should have a great lil flyer!

oh and you can almost get the kits as cheap wholesale, and you know what your getting!
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Feb 12, 2015, 10:28 PM
Buildn it one stick at a time!
G.F. Beurling's Avatar
Thank you for the encouragement, as well as the technical input about dihedral, right, and down thrust. I'll follow that advice.

I too would have thought that there were a whole bunch of other small 42" -50" planes to you are suggesting, but I don't like ARF's or RTF's which elimnates a lot. I like the satisfacton of flying a kit plane that I built, and unless I am overlooking what is available, there are few suitable kits. I watched the 42" Herr Sig Cloud Ranger and Star Cruiser $50 kits on youtube and they fly too fast. The $50 Telememaster Micro at 34.5" is small and squirelly, and the Mini Telemaster 45" V2 kit seems fine but is a rip-off at $90 and I refuse to pay it! It is very nervy to charge $90 for the same 45" kit that was going for $40 - $50 just 4 years ago. I can get the 63" Seniorita at the same price or less.

Agreed, bigger fly's better and a 63" Seniorita would make a very nice example. I already have a glo full size 63" Seniorita. It has such a large fuse and wing area, that even in lectric I would find it hard to regard as a "casual" park flyer. I don't know about electric, but I'm also under the impression that a smaller 47" Seniorita would require less powerful and costly motor and components. (??) Not sure if I'm right about that, or the difference between the two motor sizes and batter packs between the 47" and a 63" is too small to consider. (??) Keep talking, and I might just build me another 63" right out of the box as is!!
Feb 13, 2015, 01:57 AM
B for Bruce
BMatthews's Avatar
Originally Posted by Randall Miller
I'm really just wanting a VERY calm and easy park flyer. Believe it or not, I love building and have some really nice large flying models to show off, but I still haven't mastered flyng! .......
I don't doubt that you'll enjoy doing a Senioreta. But from what you typed in the quote here I KNOW you'll enjoy some of the old timers. And I know from building and flying my own old timer RC models that they are very docile. You'll soon be shooting touch and goes and flying in tight with good control and confidence with an old timer.

For smaller old timers the typical setup is rudder and elevator with throttle added often as not. In this case it would obviously have throttle control.

If you like the idea of parts cut out already check out some of the laser cut short kits from Bob Holman. Check the Gas Models under the Old Timer heading at .
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Feb 14, 2015, 05:33 AM
supreme being of leisure
ZAGNUT's Avatar
just recently built my first electric plane as i wanted something small to fly in the fields that are walking distance from my home....go out in the morning and get a couple of flights in before work instead of waiting for the weekend.

being very familiar with 1/2A planes i built a simple stick type of thing with a 6"x 36" wing, bought cheap gear...i think the 1300mAh 3S batteries, ESC and motor were all around $10 each. was really surprised when the plane came out to 16oz. with landing gear as the same size plane would have flown well at 20oz. with a cox reed engine back in the day of stuffing regular size radio gear in small planes....stuck a regular 6x3 prop on the motor and got 14,000 just like a cox product engine would do and it flew just like a sedate 1/2A would only with perfect throttle control.

then i discovered one of the neater things about electrics: putting a larger prop on makes more power! measuring current i saw that i was at ~65 watts with that prop but that the motor i was using was capable of closer to 200 watts. so now i'm flying it with 7 and 8 inch props and thing is a little beast. built a shorter aileron wing with no dihedral and it's easily one of the wildest planes i have but anytime i want something sedate i just pop the old bent wing and smaller prop back on and it's a trainer again.

only sad part is that i don't see myself ever going back to 1/2A glow power for the little stuff. the larger stuff is still safe though.
Feb 14, 2015, 06:12 AM
Registered User
AA5BY's Avatar
It sounds like you are capable of scratch building, which opens the door to finding something that makes your liver quiver. Finding an object that you can be passionate about adds greatly to the fun.

Good hunting.

One of the local guys scratch built his version of a small electric slow stick a while back and it flew well. Such a plane once trimmed out, could probably serve as a self trainer for anyone who has done a little flight simulator time.
Feb 14, 2015, 08:09 AM
Registered User
hul's Avatar
Originally Posted by Randall Miller
In the meantime I'm curious and was wondering if the flying weight ends up at about 3lbs, what kind of motor, battery, servos, and controller would you recommend?
3lbs is very heavy for that size. At 75% scale it shouldn't weigh more than 30 to 40% of the original. Coming from larger planes you will probably tend to build too heavy, guess how I know...

42% would be what you get if you scaled everything exactly 75% (0.75^3=42%). But it will feel fast at that weight and you should try to be lighter, ideally 0.75^4=32%, but that may be hard to reach.

You'd only need about 100 to 150W for that weight.

This article gives you one way how to figure it out:

Feb 14, 2015, 12:45 PM
Buildn it one stick at a time!
G.F. Beurling's Avatar

I'm thinking you're right about one "never wanting to go back to 1/2A" . For the first time in my life I started to shop for electric and I see that motors and batteries to fly .46 to .60 planes aren't expensive. I might like it a LOT and never want to bother dragging around jugs of glo fuel ever again. PS Stay safe over there my friend!


Yes...the Kadet series of trainers does that "passion" thing for me. And over the last few days, I like the idea more and more of a Seniorita design.


Yea.....I agree with you, and I was thinking that 3lbs is too heavy! And yes, I admit I have tendency to build heavy coming from 20Lb planes....but knowing that, I feel like I can now deliberately make a concentrated effort to at least try to build light and use lightening holes, etc.

To build a downsized 47" Seniorita, I still intend to use the balsa supply that comes right out of the Sig Seniorita kit, and I'm not sure if that is a mistake or not. (?) I'm hoping that the Sig Seniorita at 63" is a VERY light wing-loading designed plane, and I'm guessing that the 1/16" and 3/32" balsa including the hardwoods for the spar, will work in a 47" version too while still retaining structural strength so I don't have to worry about catastrophic failure like wing breakage in flight, etc. I hope that when I downsize that plane to 47", it will come in considerably less then 3 lbs. Perhaps one good place to start will be to substitute the Sig Seniorita trike landing gear with one that is designed for a 2 lb electric plane. (??)

My secondary option is to build the 63" kit as is from the box. But, I didn't even want a motor and battery pack that large, and I don't consider a 63" plane with all that oversized fuse and wing surface area as a " Park Flyer" . It's tempting just for the purpose of keeping everything simple. I'm Kinda torn between doing a 63" kit safe and right, but larger then a "park flyer" and kind of a boring build to me.....OR, having fun and enthusiasm building my own 47" scratch built........but which may NOT fly well. (because I gambled and took a chance not knowing if the balsa from out of a 63" kit would be too heavy) That would not be a good outcome either!


If anybody else too would like to venture and guess if I should be able to use the light stick lumber right out of a 63" Sig Kadet kit to do a downsized 47" plane , please feel free to comment.
Last edited by G.F. Beurling; Feb 14, 2015 at 01:03 PM.
Feb 14, 2015, 01:16 PM
B for Bruce
BMatthews's Avatar
I think you'll find that a lot of the parts cannot be cut smaller and still keep things where they should be. Things like spar slots in the ribs being one such factor. After all the parts are already die or laser cut and you'll be stuck with trying to work around the various shapes and cutouts.

You'd be far better off to keep the kit as the kit is intended to be and get the plans reduced then cut the parts from sheet and strip balsa and spruce spar wood that you order up from Sig, BalsaUSA or some other supplier.

And because you are going electric things like the firewall and motor mount could be reduced in thickness for some added weight savings. In addition the wood used for the tail could be reduced in thickness by 1/16 for more weight savings.

These are all options that are not open if you try to cobble the reduced size park model from the wood supplied in the kit.

Pretty clearly you are not that comfortable with the decisions and knowledge needed to correctly make a model from a reduced size plan. If you insist on wanting to make a reduced Seniorita I would suggest that you find and download a bunch of similar size old timer plans and use the wood sizes and construction methods indicated on those plans as a guide for a scaled down construction for the Seniorita as far as wood sizes, former spacing, rib spacing and so many other decisions are concerned. The reduction you are contemplating isn't something that can be done using the construction methods and sizes from the full size plan. If the reduction was a smaller difference then sure. But you're reducing by 25% and that's a lot. Wood sizes and parts spacing needs to change to avoid having an overbuilt small size model. And again that makes trying to build the reduced size model from the kit supplied materials pretty much a non starter of an idea.

Not to mention that you're paying a lot more for a small model than you need to.

And if somewhere along the way while looking at such plans if you happen to find a design example that looks good to your eyes then by all means build THAT one.
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Feb 14, 2015, 07:39 PM
Buildn it one stick at a time!
G.F. Beurling's Avatar

First off, thanks for the help.

I was planning on making stencils of the kit parts simply by drawing around them with a fine point pencil. Then you simply make photo copies of them, and along with the plans you can decrease or increase the scale of the plane as desired. I've done this successfully with my 25% enlarged 89" Astro Hog. This is NOT a unique method, as I know of others who do the same thing to enlarge kits when plans don't fully show the precut parts. Yes, you are right that I am not comfortable making the structural decisions. I must go by plans or seek input from others with more experince. I had a very experienced builder at a LHS guide me what lumber to use for my 89" Sig AstroHog to beef up construction fom it's original intended 7lbs to 18.5 lbs! Silk& dope, & 1 1/4lbs of lead weight to the nose all taught me a good lesson about excess weight! Completing it and watching it fly was a very gratifying moment some 20 months later, but I don't want to do all THAT again. Sizing down the Seniorita should be a LOT simpler I hope. LOL. The Seniorita is already kitted with very thin and light formers, ribs,sheeting, etc. Because those components are already about as thin and light as material gets in a small plane, I thought I might get away with using that same exact balsa that's already in the box. I don't think any of the notches will show when sizing down the balsa formers and ribs, but even if they did, the width of the balsa I intend to use for the 47" will be the same stuff supplied for the 63" kit....which again is very light 1/16", 3/32" and 1/8" balsa. With this light and thin balsa, I'm not sure how much more weight the plane will suffer placing parts 25% you had voiced concern about.

Anyway, just to be safe, I think I'll heed your advice and search for a 45" to 50" electric kit. That way I can examine the plans and balsa parts in the box and study them. Then I can always sell whatever kits and/or plans that I don't use. The biggest problem I'm having in recent years is locating planes that are NOT ARF'S! (ARF'S have covering and you can't always see or know what parts are under it and examinme the construction) I know that you suggest shopping some Golden Era plans. But I really prefer to study stuff and do touch-feely with kits if they are available.

Thanks again for the help!

Here's a photo of a Seniorita I built 20 years ago. It's been flown once. It was my first RC plane. Yep....I'm partial to the Kadet family of planes.
Feb 15, 2015, 01:10 AM
Registered User
Aviron's Avatar

Too small?

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