doxilia

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Whenever I find myself typing in Build Thread (hasn't happened too often but still...) before a post I get both excited and at the same time... feel the weight of the words. As if somehow, since I've begun it, I now have the responsibility to finish it! But that's a good thing, right? Keep motivated despite, shall we say, life's interventions...

Anyhow, without getting too philosophical, I decided, for fun and practice, to build a lil' Deception. It'll be a buffer project - something to diversify the building experience while working on more serious [sm=50_50.gif] projects. I'll be picking up wood as I go. (And as is now traditional, in the first post I manage to get in a sentence that I do a double take on! . If you'll excuse the editorial.) For now, I'm just planning on getting the wing and stab done since I've got cores done and I've got sheeting wood from my LHS.

A few pics of the larger sibling to get us started...

doxilia

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Here are the specs of the plans I reduced and a few planning shots.

I first had the idea to build the Deception around a 28 year old ST G20/15 that I have which dates back to my CL days. I bought the engine in Milan while on a trip back to the old country when I was... 14 I think. Great hobby store called Movo. I remember the feeling of not knowing what to look at since my time was limited and I wanted to see and touch everything. In any case, the ST is still silky smooth but I had to find a RC carb for it so, with a little help from our favourite auction site, I picked up its sibling - a NIB G20/23 - in this case with a RC carb!

The two engines are almost identical except that the 23 has a slightly heavier crankshaft, a different head, sleeve and piston. Otherwise, the crankcases are essentially identical. Now, even though this is an engine that was designed in 1970, a 23 on this little rocket might be..., shall we say, dangerous!? With that said, given that the engine mount and crankcase are the same size, I am thinking of maybe just bolting in that 23... I also don't have mufflers for either one so, what can one do in such a situation other than pick up a header and 3.5cc muffled pipe from Mac's? [8D]

70s Flyer

Dang Dave, How do you have so much time for this building nonsense? If you want a full size one,you know where it will be soon.

doxilia

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I got started on the wing retracts yesterday. My left gear well (right panel) somehow ended up with unparallel sides for the strut length between the wheel and the mechanism. Something I'll have to fix as it will bug me otherwise. I'm also debating on whether I should stick a couple of dowels through the gear mounts into the cores... I picked up some dowel today. What do you guys say?

Next I'll have to make a shaft for the pushrods to the wing root as well as the servo wells for both the gear and the ailerons. I'm a little undecided about the aileron setup since two servos might actually be lighter than one servo centered behind the gear servo with torque rods (these weigh more than a micro servo!). Food for thought... any suggestions out there?

I'm also not sure about servo's yet. HS-55's, HS-65HB's, HS-82's... I think I will be using Hitec's as I'm not in the mood to drop $ on JR servos. Perhaps those Tower/Hobbico servos might also do nicely although they are a little pricier. Something sub $20 would be nice considering I'll have 6-7 of these in there!

Maybe 55's for ailerons, 65's for elevator and rudder, a 55 for throttle and nose gear and an 82MG for main gear... would that work?

BTW, she will ride on trike gear.

Ram Jet

One engine has no cooling fins on the head. It's not a marine engine is it? Looks like you're building on a foam core. What type of sheeting are you going to apply. I would guess 1/32" ply with epoxy? Nice start on a very involved project.

Bill

doxilia

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Hey Bill,

nice to have a first response to the project! (Oops, second, I just saw your post Rich.)

Yea, believe it or not, the G20/15's were made that way. I think there was also a G20/19, if I recall correctly, that had no head fins. All three engines are designed around the same crankcase. I think that since the piston in the 15 is of fairly small bore, the sleeve and crankcase are able to absorb/dissipate enough heat. I've actually run that 15 a fair bit on CL planes at full rpm's and there's not a hint of varnish on it! So it must be cooling adequately. I think I used to run 10% nitro in it.

Yup, the wing and stab are foam core. I picked up 1/32" balsa for the stab but thought I might just use regular 1/16" balsa for the wing. 1/32" ply might be a nice option too but I'm thinking that a thicker airfoil might be preferable (I want to be able to see it after all... ) and 1/16" sheeting would actually be a better match to the plans.

... I was hoping someone wouldn't say something like "a very involved project". In my mind I figured I would just get it done when I needed a little distraction... NOT! Thanks for keeping me honest Bill.

David.

doxilia

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Rich,

you don't say! I've got to see your warehouse one of these days!

Hmmm... tempting. I do have a nice YS AR as well as an OS Hanno just waiting for a home... Keep us posted!

Time...? Small kids. You actually have none but you get used to sleeping less since you're always being woken up. I typically work on the hobby 2-4 hours in the evening after the kids are asleep when all is quiet... I have a window at the moment as the little one is still nursing. I won't expand further on what that means.

zubba

Dave,
You sir have many coals in the fire lol.
Another great project though i must say!!
What is the max model memory in your tx??
I must say you have great taste in ships though

-jason

rainedave

My Feedback: (1)

Cool project. That .23 on a 40" model is going to be wild!

I also picked one up at auction recently. Mine is a used example:

http://www.rcuniverse.com/forum/fb.asp?m=8181718

David

PatternPilot

My Feedback: (58)

Just a reminder guys, Dave has contacted me about several different size Deceptions to go with the current SPA legal 60 size that i manufacture. I will be making a new canopy plug and mold for the sizes we pick, a 40 size and maybe on smaller for electric or small glow. We currently have full size 60 size cores , plans, and canopies in stock.

I will be working on getting the new sizes over the next few weeks with the help of Dave, and hope to be able to release them in January.

scott
www.rcfoamy.com

doxilia

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Gents,

thanks for the positive and optimistic comments. Jason, my TX memory may max out one day but that will give me an excuse to pick up an X9303 .

David, I'm glad this thread caught your eye. I know you're fond of the smaller projects. It should be fun with the possible exception of things like engineering how to get all the gear in there! (I recently managed to install 4 servos, retracts, flaps and ailerons in a 1/2A FW-190 built up wing so I'm feeling optimistic. To compensate, that fuse is superlight. The model is electric and I expect AUW to be ~23-24 oz.)

My primary concern at the moment is the nose gear and servo as well as the fuel tank. As is oft necessary, I will be making the fuse wider than the scaled down width shows. F2 is just about 2" but the FW is narrower and I want a FW that is 2". There are no commercial tanks (that I've found) 3 or 4 oz in volume that require less space and I'm not going to put a 2 oz'er in there. I'll see what percentage I have to widen the FW and then scale the other two formers accordingly yielding a slightly wider fuse. Thanks for the ST thread - a great resource. It sounds like the 15 might do well on an 8x4 while the 23 on the 9x4 (@5% & castor). Actually I'm not sure a 9" won't be too long but perhaps an 8.5" will be ok.

Scott, if there's something I can do to help, just let me know. I think that little Deceptions (like little Tipo's) could be all the rage especially now that a sub 45 size pattern association is forming.

David.

doxilia

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A little progress...

I got the aileron servo installation sorted out. I decided to mount dual outboard servos for simplicity and lightness. They may be wired as flaperons (independent channels) or via a Y-harness depending on whether the nose gear installation will require a servo (likely). I'll be using a super light 6 channel receiver (AR6100) and 6-7 servos. I also decided to go with HS-65HB's on all control surfaces as the HS-55's are a little flimsy for a high powered mini pattern plane. I'll probably also use an HS-65HB for the mains and 2 HS-55's on throttle and nose gear.

The aileron servos are mounted centered on the CG line. I've mostly completed the prep work on the right wing panel. The left panel still needs its servo lead tunnel as well as servo well sheeting. The gear servo center section is done except for the pushrod tunnels.

Wing and stab sheeting has also been prepared so, with some LE, TE and aileron/elevator stock (which I need to pick up), the flying surfaces should come together pretty quickly once the wing prep is complete. I'll be using Zpoxy laminating resin for the sheeting which I decided to build up with aliphatic resin (typically I would use CA to build the sheeting but foam safe CA is rather precious).

I'm looking forward to some sheeted wings and stabs!

David.

rainedave

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David, this is looking fantastic! Keep the posts coming.

David

doxilia

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Thanks David. I'm having fun!

I did a few back of the envelope calculations and amended my plans to better reflect what it is I'm building. In particular I was concerned with the wing loading given that I'll have trike retracts and a full radio setup. Also, I'm widening the fuse a little which reduces the effective wing area present for lift.

The good news is that if I manage to keep the weight down, she should be ok (I think ). Even though there's only 40" of wing span, the wing is quite wide compared to many other classic pattern planes. In short, I should have a total of 308 sq. in. of wing area which translates to a wing loading of 15.9 to 18.7 oz./sq. ft. for AUW of 36 to 40 oz., respectively.

If anyone has any magic insight or rule of thumb for the wing loading range aircraft in this size should have, please do chime in. David, I enjoyed reading your SureShark build thread and will get back to you. I noticed that your build came in very light at ~24 oz to yield 14.4 oz./sq. ft! If I can get the Deception to come in at ~36 oz. (~15.9 oz wing loading), I think she might be golden!

David.

doxilia

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Has anyone tried using this sort of vacuum bag with a simple vacuum cleaner for foam core sheeting purposes?

My wife uses them for storage and they struck me as possibly useful. Dunno how good a vacuum they hold nor if the cleaner is able to create the necessary suction... I'm thinking I'll need about 30-40 lbs of weight on the wings when sheeting them.

David.

doxilia

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Mmmm... now I'm a little confused. What to do...?

Have you guys seen one of these before? K&B 18 Aero. They claim 1.2 HP @ 18K on a pipe w/ 30% nitro. [:-]

It was practically a gift.

somiss1

My Feedback: (5)

My K&B .18 is a DOG! You would be much better off with a good, lightweight .15. When I first saw the .18, I was glad to see a K&B product as I always had good luck with them. However, this one is not a screamer like my old K&B's. Look up previous threads on the .18 and you will find that others have had the same experience. I threw $90 away!
Frank

doxilia

My Feedback: (3)

Frank,

that's too bad... [&o]. It looks like a nice little engine. I actually picked it up for $30 plus shipping so maybe I got lucky. I do want to try it out on a little 2.5cc pipe though.

The ST G20's I have faith in so maybe I'll just go with those.

David.

somiss1

My Feedback: (5)

I tried a mousse can muffler on mine and it only got me the rpm's of the engine without a muffler. The G20's will eat it alive! I did want to inform you that the G20's have a sub-induction cylinder and sleeve which is not conductive to pipe use. It's a shame as I love those G20's!
Good luck with your engine and let us know how it runs on a pipe. I really like your thread as I had two Deceptions and loved them.
Frank

doxilia

My Feedback: (3)

Frank,

thanks for pointing out the issue with the G20's and pipes! I noticed that the 23 and the 15 have different sleeves and pistons. The 15 looks like a regular induction sleeve with a flat piston head while the 23 has a lapped piston and a much thinner sleeve. I have never run this particular 15 with a RC carb but a friend of mine back in the day had the same engine with the RC carb shown on the 23. I'm not clear on how sub-induction works so if you can explain that would be interesting.

Given the 15 and 23 don't seem to have the same guts, do you think the 15 might lend itself to pipe use while the 23 only to muffler use? If not, what mufflers would you recommend for these guys? I don't think the ST will be easy to come by...

Regarding the K&B, MECOA states a figure of 1.2 hp with a pipe and 30% nitro! Maybe a little overstated but I would hope that it could turn an 8x4 at decent rpm's with or without a pipe. Did yours just not run well? Wouldn't come up on rpm's? or maybe just not reliable?

I'm glad you're enjoying the thread. It'll get more interesting soon - I've got a fairly complete list of wood and parts needed to continue making progress. For one, I've got to sort out that firewall for width, motor mount and nose gear. This is basically why I'm tossing around engine ideas as the mounts for the G20's and the K&B are different. I'll most likely be using Robart's small 2 lb. nose gear unit and a Dave Brown Lite Flite 1.5" foam wheel.

David.

somiss1

My Feedback: (5)

David,
Please check out this:http://www.rcuniverse.com/forum/m_64...tm.htm#6451209.
I am not a expert in motor tuning so I could not explain the sub-induction porting problem. I remember reading about it when tuned pipes became popular. I do remember that the old flow-through mufflers were used for the .23's and folks had problems when "closed" mufflers became mandatory. Maybe some of our more learned friends here could explain this better than I ever could!
My experience with the .18 has been with a Herr Extra and I was very disappointed with a 8/4 prop. It runs ok, just not very powerful. For $10 more, I could have bought an OS .15CVA. However, since you only paid $30 for yours, try it on a stand and see if yours has the power that you need.
Keep up the good work!
Frank

Dean Pappas

Hi All,
Back in the late 60s and very early 70s almost everything I had built was around my pair of Tigre 23s. Dynamite little engines, and they responded poorly to any kind of muffler.
Any back-pressure killed both the power and the friendly running characteristics.
Regards to all,
Dean P.

teamvortex

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Hey, I just got into this thread. Thanks for the photos of my two Deceptions that are flying in the SPA events. Boy, those photos sure do get around. The plane flies really well and there are a couple more in the works down here. Both of mine are now using OS61FX's for power on 12/8 APC props.

Rich

TeamVortex Brooksville, FL

doxilia

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Rich,

Thanks for posting in the thread.

As you must know, the pictures come from the Trenton Flyers RC club pattern image web site. I assumed the planes belonged to two different people. I read and enjoyed your two page article on your story with the Deception.

There is a third photo on the site of the classic trim model (the one with the checkered wing bottom) but it appears to be the same plane as shown here except it looks like it was retrofitted for fixed gear on the fuse and a tail wheel. Is that something that was done post build to accommodate SPA rules?

I hope to finish this one over the winter (as noted it's a for fun build - maybe they all are...) and next fall build a full size one around either an OS Hanno or a YS 60 AR.

If you have any other pictures of your models, please do post them here!

David.

doxilia

My Feedback: (3)

Dean,

thanks for that info. I've always thoroughly enjoyed reading your column in FM!

ST's are engines from my childhood memories and thus I'm quite fond of them. Based on your comments, would you think that an open pipe (e.g., a Macs 1110 or 1120) might be a better muffling solution for the G20's? These engines used to come with open type mufflers but as you mention, they didn't do much for the engines performance.

David.