Mini Powerhouse Build Thread

[Ragwing]

I thought I would start a thread for the build process of my first electric model-I could certainly use the advice. Since I have recieved encouragment and advice already from the "vintage" crowd I thought I would keep it in the vintage forum.

My subject will be a scaled down version of Sal Taibi's 84" FF Powerhouse. I scaled down plans that I got from The Plan Page to a 21" span, using Andrew Donatelli's Tile Print. I drew in an extra 3.5" on each wing, for 28" total and approx 95 squares.

After asking a few questions and reading many threads I have decided on the following power/radio setup: GWS LPS-RLC B motor, GWS GS-100E ESC, GWS Pico Reciever, two micro servos (Hs-55 or equiv.) and either 160 mah or 400 mah Nimh 4.8V battery, weighing in at .4 and 1.08 oz respectivley.

I'm plan covering and trimming the model with tissue, and I'm hoping for an AUW of 3.5oz (with the lighter battery). I don't think it will be a floater, but I know it will be cute, and hopefully fun to fly at the park. I'm really looking forward to the clean, quiet reliable power that comes from electric, plus the ability to play with small light planes like this one.

Currently the wing and elevator are built, I took the liberty of adding false ribs for a weight penalty of .3g. As you see it the wing weighs 6g, I'm a little worried about it's stiffness-or the lack there of. The "spar" is a set of 1/8 sq balsa strips one running along the top of the ribs, and one running along the bottom. I know the model will be light, but the whole wing has a lot of flex and it worries me a bit.

I tried to build some airfoil into the horizontal stab it came out at .9g. I'm not sure how I will hinge my control surfaces yet, I've heard people talking about using tea bag material so I will probably experiment with that when the time comes. I love Monokote hinges, but since I'm not using monokote this time....

I also got a little package from Balsaproducts today. Great little goodies inside-and reasonably priced too, this electric stuff looks like it will be fun. I'm going on vacation at the end of the week, but when I get back I plan on spending a lot of time with this project, I'll see what I can get done in the mean time.

I appreciate any advice you guys have, thanks!

Derek

[Tim Wolff]

I've got one of these frammed up for SAM 1/2A Texaco. You can add shear webbing between the spars to increase the strength of the spar structure of the wing. Torshional (sp) stiffness will have to come from the covering or some diagonial bracing from the rear of the spar to the trailing edge. You should also be quite safe with the elevator on only half of the stab. Looks like it's too late for that though :)

IMHO, the stick frame is too much work to trust a GWS RX. I'd use an FMA M5 dual conversion or Berg 4.

[Ragwing]

Tiberius,

Thanks for the suggestions; I will definitely add shear webs. Hopefully the tissue will take care of the torsion problem . Also, thanks for the warning about the receiver. I did a bit of research before I purchased it and it seems as if for every person who has had trouble there is always some other guy who jumps in and says how he hasn't had any trouble. I believe both people, but for my application I decided to give GWS a shot-it is so light and cheap. I plan on flying this model close in, I have to since it's so small. And to my advantage I fly alone, so radio interference shouldn't be an issue. If the reciever glitches and crashes my plane, I was warned I'll know for sure to steer away from GWS. But I really do appreciate your advice and warning.

Progress....

Tonight I built the rudder, it weighs .42 g. Then I moved on to start framing up the fuse. Right now I'd really like to hear about any slick and light methods for mounting electric motors. I've seen mounts that consisted of a dowel and wire holding the motor on. But that seemed a bit crude and unserviceable. But maybe that's what I'll have to do, I don't know. Any ideas?

Well my schedule will take me away from the plane for a little over a week, but I will be able to check in here and plan in my head.

Thanks

Derek

[Tim Wolff]

The RX will prob. be ok when you are alone. I've seen plenty of them getting hammered at indoor sessions. Be very careful with company.

Maybe I'll finish mine too :)

[Steve Moskal]

Derek,
We all appreciate your work here. You are inspiring me to get my BMJR Rambler out of the box and onto the board. Your approach looks about right for using my Spirit of SAM experience in a fun project.

Could you tell me the source for Andrew Donatelli's Tile Print? A Google search didn't pull anything up.
Steve

[Ragwing]

Steve & Tiberius,

Thanks for the encouragement, by all means finish your projects and post pictures. I'd love to hear what gear you are using-this is all so new to me.

Tile Print was developed by BipeFlyer on RCU, a really nice guy who I got to meet a few weeks ago. He released a beta version for free, which I have. It's a great program, simple and extremley accurate-but the beta had a few hang ups. He is currently selling copys of a newer version with a few more options, you can also get an evaluation copy. Go to:

http://www.blackflight.com/planes.asp?plane=tileprint

From what he tells me there may be a review in RCFlyer before long.

Derek

[vintage1]

Right now I'd really like to hear about any slick and light methods for mounting electric motors. I've seen mounts that consisted of a dowel and wire holding the motor on. But that seemed a bit crude and unserviceable. But maybe that's what I'll have to do, I don't know. Any ideas?

The classic way with GWS IPS geraboxes is to use a stick that pushes into the back of the box. Then gluse that to a transverse palte at teh correct siudethrus/dwonrthruist angle. The plate should carry back to a former around teh lamding gear area and be loacted there for best trnsferral o landing shiocks.

Then the front of the plate can be located on a cross member that you can glue into the front structure somehow.

The GWS motors need to e pulled forward to remove, and that generally means a removeable cowl.

Frankly you probably need to desin a whole new nose.

[Rotten Robbie]

I built a 24" EPFF from the same plans 2 years ago. It is powered by a MM-1 with 3 110mah NiCds. Almost lost it one.

Current project is a 32" Brooklyn Dodger from a R/N kit. S280 power with a parkflyer radio. The Brooklyn Dodger is another of Sal Taibi's designs. But it has a dificult cabin to work in.

Robbie
SAM 8
Seattle, Wa.

[Cebola]

Cute model!!!!!!

[Ragwing]

Robbie,

That really is a cute model you have there, I hope mine turns out as well as yours has. Maybe we can get some pics of the Dodger when complete? I'll be over in Seattle quite regularly this summer, I'd love to come to a SAM event to see FF and some great models. Maybe we can work it out.

Vintage,

Thanks for the instructions-it sounds straight forward enough. I'll go the removable cowling route, it was going to be open on the bottom anyway for cooling.

Derek

[Ragwing]

It's been a bit since I got a chance to work on the powerhouse, but this weekend I made some progress.

I still need to do work on the wing mount, landing gear and misc re-enforcements, but at this stage the fuse alone weighs 7.36g. I followed Vintage1's advice on the motor mount, but decided to a carbon arrow shaft instead of a dowel. I'm not quite sure how I will actually attach the motor to the shaft, but I'm thinking along the lines of a set-screw.

Upon the sage advice from Tom Anderson, and his suggestion that I review the "Diddlebug" thread over in the Parkflyer forum, I have decided to change the power setup. I've purchased a replacement motor that will use with my current gearbox resulting in a LPS B2C-B. I plan on running 7.2V instead of 4.8, the motor will be lighter and the current draw less. Plus the 4.8V ESC that I had selected has an auto cut at 3.2V where the GWS receiver needs 3.6 to operate :eek: So a new ESC and a couple extra cells soldered onto my current 4.8V packs and I'll be in business.

Once my new goodies arrive I'll be able to look at radio installation and battery placement, but until then I can probably find a few things to work on.

[Ragwing]

Here's the latest:

Balsa work is basically finished; control surfaces are hinged with tea bag material. The wings bolt on with two 4-40 nylon screws. Total weight: 18g

Yesterday I was taught how to assemble battery packs, so I added two cells to all my 160 mah packs to accommodate my new power system. I charged one pack and bench ran the entire setup. I love starting the motor with the increase of the throttle, coming from 1/2A with no throttle this is a real novelty and treat. I was quite surprised, I got nearly 12 min of run time at 3/4 to full throttle. However I didn't move the the servos much during the test, so run time will be shortened from the 12 min by a bit. I know putting a motor in a vice isn't a great idea, but I was careful.

That's all for now, I'll start mounting the servos et al next week. I can't wait to start covering.

[Ragwing]

I've done a bit of work since I last posted, the powerhouse is finished. This process included installing two hs-55's with a nylon thread pull/pull system, shortening the leads on the servos and ESC, covering with tissue and 2 coats of dope. The "Powerhouse" logo comes from the original plans; I printed it onto the tissue using my inkjet printer. All up weight is 3.3oz (94g).

This morning I took the plane out to test fly, and the good news is that it flies and it is still in the same condition. The bad news is that it is underpowered. The plane is fine until you try to turn, then it just mushes around while slowly sinking. I have a different prop to try on it, and if that doesn't work I'll need to think about another cell on the battery pack-or what? Despite the problems I am pretty happy with the model so far, it looks great in the air. I think I'm a convert to electric.

Derek

[Ragwing]

More Photos:

[JMP_blackfoot]

Sorry, duplicate posting.

[JMP_blackfoot]

Could the mushing during the turns be caused by a lack of dihedral ?
I just pulled my copy of "Air Age Gas Models", where the plans on page 93 and
96 show 8" dihedral under each wing tip for the 84" wingspan of the original ?
What size prop do you use ?
Congratulations on a fine model :cool:

[Ragwing]

JMP, thanks for the advice. There is a bit of dihedral built in, but not much. I tend to reduce dihedral to improve the looks of models, but I think it may have bit me this time. Still I'd like to see how it does with more power, whenever I turned it would just sink, ususally into the ground. I never got the plane higher than 12ft or so. I was using a GWS 6050. THe 6030 is the reccommended prop for this motor/gearbox but it produces even less thrust. Going up to the 7035 should produce a little more thrust according to the specs; I'll look for one this weekend. Upon closer inspection of the motor specs they do not reccommend 8.4V on this motor, so an extra cell is out. The only other solution is lightening it up a bit. I can save about 8g by buying the 4.2g Bluebird servos. And I could make the switch to Lipoly-but I'd really like to use the battery packs that I have.

[Graham Stabler]

Thought you might like this, 8" span version:

http://www.rcgroups.com/forums/showthread.php?t=291438

[tad]

Hi,
Great looking model.
You probably didn't do any favours for the motor by running it on the bench at 3/4 to full throttle for 12 minutes though. This may be a reason for the lack of power.
Keep up the great building.

[Ragwing]

Graham, my hat is off to you! That is a cute little model, all it needs is a little color. Thanks for the link.

Tad,
Thanks for the advice. I'm really new to electrics, so I'm curious as to why it is a bad idea to bench run motors.

As far as the plane goes, I haven't tried flying it since the last post. I removed the covering from the fuselage to make repairs and revamp the control surfaces and lost interest. The gear is going into another plane, and this time I'll be using Lipo's. I'll come back to the powerhouse for sure.

Derek

[Steve Moskal]

I've done a bit of work since I last posted, the powerhouse is finished. This process included installing two hs-55's with a nylon thread pull/pull system, shortening the leads on the servos and ESC, covering with tissue and 2 coats of dope. The "Powerhouse" logo comes from the original plans; I printed it onto the tissue using my inkjet printer. All up weight is 3.3oz (94g).

This morning I took the plane out to test fly, and the good news is that it flies and it is still in the same condition. The bad news is that it is underpowered. The plane is fine until you try to turn, then it just mushes around while slowly sinking. I have a different prop to try on it, and if that doesn't work I'll need to think about another cell on the battery pack-or what? Despite the problems I am pretty happy with the model so far, it looks great in the air. I think I'm a convert to electric.

Derek
Derek,
I just downloaded my eval copy of TilePrint. Thank you. And I love the Powerhouse. Your use of tissue and your logo work shows your love of detail. I'm guessing your experience with this size of model will be a source of inspiration to more of us. I now know I'm going to get the BMJR Rambler kit out and plan my hardware. I flew my Earl Stahl Weight Rule in a postal Spirit of SAM sponsored by my SAM 117 (http://www.cometkid.com/) chapter. I'm now going to get the plans back out and do a lighter version. Tissue covering will be a factor as well as a pull-pull system.
Steve

[Gonnacrash]

Steve,
I'm mailing off an orig kit of mine "Spearhead" http://www.rcgroups.com/forums/showthread.php?t=233796
to Brian at BMJR in the morning. He has shown interest in it. It flies really really great. I hear his kits are NICE. I'm thinking of going electric with my current flyer.
Love the old timers... have a 90" Buccaneer that is over 50 years old that I just put in the air... a dream to fly. Let us know how the Rambler does.
Don-Basehor, Ks

[vintage1]

Ragwing: Can you post up exact specs - wing area, weight, motor, pack gearbox and prop?

It sounds like you have too little power, or pitch speed, or both. None are insurmountable!

Its too peretty not to fly well.
:D

[Ragwing]

Vintage1

No problem,

Area: 98 in^2 (3.5"chord X 28" Span)
Weight: 94g
Motor: GWS LBS B2C
Prop: I tried a 7x3.5 and a 7x6
Pack: 7.2V 160 MAH NImh
Radio Gear used: GWS reciever, HS-55 servos, GWS Speed Controller.

I would love to be able to use this power setup again, succesfully since I have 3 of those nimh packs lying around. But I also have a 7.4V 250 mAh Lipo, and Pixie 7 controller. Additionally I have a GWS LPS B2C-C motor gearbox combo thta I could put on. And a 4.8V motor that I could swap in for extra power, all be it a short lifespan.

Thanks for your help!

Derek

[Steve Moskal]

Steve,
I'm mailing off an orig kit of mine "Spearhead" http://www.rcgroups.com/forums/showthread.php?t=233796
to Brian at BMJR in the morning. He has shown interest in it. It flies really really great. I hear his kits are NICE. I'm thinking of going electric with my current flyer.
Love the old timers... have a 90" Buccaneer that is over 50 years old that I just put in the air... a dream to fly. Let us know how the Rambler does.
Don-Basehor, Ks
Don,
How neat is that!? I was guest-flying Jay Burkart's Buccaneer on li-po power at the Mid American Free Flight Champs & SAM Fly-In at Lawrenceville, IL this month. I don't think it was 90" but the new battery technology made me really take notice. I have an 020 replica kit that wants to get out of the box and into the air.

And, yes, BMJR kits are very very nice. :D
Was 1961 the first year the Spearhead was kitted?
Steve

[Gonnacrash]

Steve,
Spearhead kit that I shipped off to BMJR is Eagle Model Aircraft Co. Spearhead Jr. with 44" W/S and 300 sq in wing area. The plans are dated 1944. However there were some produced in 1941. Said that was designed for a .60 spark, but the plans show Bantam .19 spark. The OS 15 will take it nearly straight up, way too much power !
Hope Brian (BMJR) elects to produce it as it is a great flyer !
Don

[Steve Moskal]

Steve,
Spearhead kit that I shipped off to BMJR is Eagle Model Aircraft Co. Spearhead Jr. with 44" W/S and 300 sq in wing area. The plans are dated 1944. However there were some produced in 1941. Said that was designed for a .60 spark, but the plans show Bantam .19 spark. The OS 15 will take it nearly straight up, way too much power !
Hope Brian (BMJR) elects to produce it as it is a great flyer !
Don
Thanks, Don,
You know the drill on the SAM cut off for models. I was hoping this would be a SAM-legal discovery. No matter. I will be building some fun ships this winter.
Steve

[vintage1]

I ran up some Motocalc predictions, and whilst it should climb on the 7x6, its viley innefficient, and has almost no pitch speed to speak of. Will barely make it to a fast trot! Will be teetering on the edge of a stall - probably its doing that on the inner wing when you turn.

You need more pitch speed. AND its hard to come by with that motor. On those cells

6x5 may be slightly better, but not much..

Oh ho. The 4.8v motor is your answer. Is it the longer can CN12 RLC?

Looks like the LPS B box (5:1) and a 6x5 will fly your model on 7.2v and that motor. Suddenly it leaps to life!

Massive climb and sensible pitch speed at last!

Even better on the 2s lipo!

You should be able to get to nearly 30mph!!!

It won't burn out on that prop, its up around 36K RPM but current and heat are well within limits. Should pull just under 2A.

Using the 4.8v motor and the C ratio (6.3) box the 7x6 comes up trumps at last. Pulls a shade more current, but a lovely hot combo.

I think from my experience of Motocalc, that the model will be utterly transformed on that motor and either of the boxes you have.

[California Condor]

The Spearhead is a SAM leagle Old Timer.

[Steve Moskal]

Thanks, Condor:
I am not up to speed on all of them. I just got the 1938 Scientific Miss America kit (Rubber Powered Gas type) that dad was never able to afford.

[Ragwing]

Vintage1,

Sounds great! Thanks for doing all that research for me. You have inspired me to try and bring this thing back to life. Yes the 4.8V motor is significantly longer (and heavier which helps fight a slightly aft CG), causing troubles with the motor running into the firewall, but that can be addressed. I'll see how far into the reconstruction I can get this weekend. Thanks again, you've given me hope that this thing will fly after all!

Derek

[vintage1]

I have played with IPS models before, and compared motocalc to reality enouh to get the feeling that not only is the predictrions of the existing setup dire enough to explain all previous problems, but that the predictions for the hotter motor will result in a stupendous little plane. Frankly if its as light as you say it is, it will simply climb like an angel, and really will do nearly 30mph. Careful when looping and don't fold the wings....:D

[mike48]

hi ragwing,,i just tried a cn12-rlc,,thats the 4.8v ipstype motor in the lps gr box with a 6by 5 prop with6.2 to 1 ratio ( c) and a two cell 340 lipo on a 110 sq in winged plane about 4 oz auw.... it draws 1.8 amps static ,,,( with the 7,6 prop it went up to 3 amps,,,)
on the 6,5 it flys great ,,,good climb ,,loops to the end of the pack,, half throtle cruise,,,
motor only barly warm after long flight...i only have 3flights on it... i was wondering if
vintage 1 had any idea how long that motor might last at those volts and amps?????
mike

[vintage1]

on two cells at 1.8A? For ever.

I flew a standrad IPS (more resistance) on 1.9A all last summer and early this year. It ended up a tree. Came down but model was totalled. It still runs fine.

Ultimately the brushes wear out, but that takes time at sensible currents. You are supposed to be able to run the low voltage motor at up to 4A, certainly 3A. 2A is so conservative as to be no risk at all.

[mike48]

thanks vintage 1,,, thats great cause i love this set up ....the reason i tried it was because i had read some of your posts about 3cell lipos with ips ... but i have a lot of 2cell packs so i thought maybe a low volt motor on 2 would be kinda like higher volt
motor on 3 ??? is there any valid logic to that ???
mike

[bolmas]

are 4.8v motors available in the u.k? if so where from?

[vintage1]

thanks vintage 1,,, thats great cause i love this set up ....the reason i tried it was because i had read some of your posts about 3cell lipos with ips ... but i have a lot of 2cell packs so i thought maybe a low volt motor on 2 would be kinda like higher volt
motor on 3 ??? is there any valid logic to that ???
mike

Totally valid as far as I can tell. The 4.8v motors should be as good on 2s LIPO as the 7.2v motors are on 3s LIPO.

I havent done exhaustive calcs, but the efficiency figures motocalc was showing and the power in/out figures look remarkably similar.

[vintage1]

are 4.8v motors available in the u.k? if so where from?
No. Jperkins distribution handles GWS and they are not stocking anything other than IPS systems at the low end.

Best place to buy is www.aircraft-world.com. As cheap and as quick as anywhere in the UK.

if I hadn't already made the 3s Kokam 340 investment. I'd get some.

[mike48]

thanks vintage 1,,, sorry for all the quetions ... i spent much less time confused when i
flew glo ....would taking a neutraly timed 6 volt sp 300 in a 5.33 to 1 gear box and agresivly timing it to draw more amps , say from 6 to 8 amp draw , then reducing the prop size to draw 6 amps have any positive effect ?
mike

[vintage1]

Not a lot.

You are shaving at very small gains. Speed 300 very efficient on 7cells/2sLIPO - if you need more go 3s LIPO and speed 400.

[mike48]

thanks vintage 1 ,,, dont need more power, i was just experimenting for effieciency...
ragwing, looking forward to your update ,,,i have all 3 B2C units a,b,c,4,5,6to 1 i like b the best on a 6 by 5 but i needed at least 110 sq in wing to fly at that speed,also the plane auw was 3 oz with etec 250 2s lipo all gws servo rx spcont .....neat set up for real small field, real slow flying ,,,, thanks again vintage 1 , i ve got more Q but i dont want to wear out my welcome !!!!
mike

[mike48]

vintage 1,, its my understanding that the Lps b2c set up ( smaller than the ips motor )is a n20 motor good to about 1.4 amp static,,,the m20 is even smaller an i think it come on the kenway motor grbox set up ive got a kenway but its to small to to pull my gws rx etc. set up ....
mike

[vintage1]

going by size and motocalc dat, I'd say you were right there.

Unles I go indoor,and special gear I can't really see a use for a plane much less than 6oz.
Which is IPS territory.

[Mchone, Jake]

WOW!

That is so awsome!