Cessna 170 Laser Cut Kit Build ( # 302 LC )

[Bill Gaylord]

Thanks Bill. Got any pics of your C150 Feel free to post here if you like.

It's one of my favorite little planes. Someday I'd like to build an enlarged version also.
http://www.youtube.com/watch?v=U7gySPVB ... e3uS3fLSoA

[SpiceMan]

WOW Bill Now that's a REAL BEAUTY
Your color scheme is just FANTASTIC also.
Looks like you've got this hobby down to a science.

[Bill Gaylord]

WOW Bill Now that's a REAL BEAUTY
Your color scheme is just FANTASTIC also.
Looks like you've got this hobby down to a science.

Not yet but thanks though. Pictures make a lot of things look better than they are.
It's just the box scheme, which for whatever reason sells me on a lot of the Guillows models and ends up going on them.

[SpiceMan]

Well, I took the pretty bird to the park on Friday, for her maiden flight. Keep in mind that this is my FIRST balsa rubber powered kit airplane that I've ever taken to completion, and attempted to fly.
Well ... Bad news, and good news:
The Bad News is: She flew like a rock.
The Good News is: I did 2 flight attempts ( each with "hard landings" ) and nothing broke.
So my conclusion is that she is way too nose heavy, and I'll be removing one of the 7 gram weights from the cowl, before attempting the next flight.
I had a friend shoot a video of the ill-faded maiden attempt(s), and I intend to post it on YouTube after I finish that learning process. Hopefully, I'll be able to up-date you all with a link to the video, in the near future, if you'd be interested to get a good chuckle.
At any rate ... I'm having fun.

[paul]

... I'm having fun.

That's what its all about, fun.

[Phugoid]

Hi Spiceman,

Please describe "like a rock", did you get a "powered glide" or did it "nose in"?. The balance from your pictures looks good apart from the fact that it looks like you haven't got the model on point contacts but it might be that I don't understand your Jig. For little models like these I just stick pins in the wing tips and balance them across two hard back books stood upright.

In any case don't rush to remove the weights. The problem is that Guillows supply a ridiculously small prop for that series of kits, it really is crazy. A model that span should need something in the order of a 7" prop to fly with rubber. Also the rubber is pretty poor (little energy storage). You maybe are just underpowered?

The other thing to check is the decalage , (angle between wing and tailplane). Try some tabs on the tailplane trailing edge angled upwards, I use cut down post it notes to make temporary ones for trimming purposes.

I would also not remove all of the weight in one hit, take out 1 piece but put say 5g back in using clay or the stuff you use to hang posters as a temporary measure (we call it blu-tack here I don't know what you call it in the US). This is because if you go nose light your model will stall and could slide back onto its tail and that's an easy way to damage things.

I apologise if you know this stuff already!

Good luck!

Cheers

Andrew

[Wildpig]

Bravo! on your first flight attempt.

I agree with Andrew, you need little tabs on the elevator or bendable control surfaces. Trimming for a glide flight usually takes half a dozen little flights. If you have tall grass, use that for test glides. The decalage is very important. Many of the kits have zero degree decalage, when it should be about 3 degrees, negative. That's a fancy way of saying you probably need more UP elevator. (After studying your pictures, again. The model definitely needs UP elevator. The horizontal tail surface appears to be parallel with the underside of the wing. 0 degree angle difference.)

O.k., I'm going out on a limb on this:
Your C.G. leveling rig. If I understand things correctly you are balancing according to the underside of the wing. The model appears to be nose down in the rig. I think if you balance with the longitudinal axis of the fuselage level, you might be better off.

67 grams, I think is a bit heavy for that size model but, it still should perform decently. Definitely not brick style.

[stx44]

Nice work on the spars- I'm trying much the same atm with my 900 series bird dog. Though I was doing it more to try and keep wing alignment correct on assembly.

Nice looking plane!

[Bill Gaylord]

Well, I took the pretty bird to the park on Friday, for her maiden flight. Keep in mind that this is my FIRST balsa rubber powered kit airplane that I've ever taken to completion, and attempted to fly.
Well ... Bad news, and good news:
The Bad News is: She flew like a rock.
The Good News is: I did 2 flight attempts ( each with "hard landings" ) and nothing broke.
So my conclusion is that she is way too nose heavy, and I'll be removing one of the 7 gram weights from the cowl, before attempting the next flight.
I had a friend shoot a video of the ill-faded maiden attempt(s), and I intend to post it on YouTube after I finish that learning process. Hopefully, I'll be able to up-date you all with a link to the video, in the near future, if you'd be interested to get a good chuckle.
At any rate ... I'm having fun.

Sounds great that it flew.
Got me thinking of my first Guillows Cessna 150 rc flight. I had a slight mismatch in the wing incidences, and a slightly misaligned rudder. Of course the rudder misalignment direction added to the problem, as the right wing not only lifted more than the left, but the tail was forced to the left. It caused a really interesting sidewinder flight, where right turns were not possible and left turns tended to bank severely downward. That was one of those experiences where I learned how critical settings are. A slight correction of the wing panel and rudder placement, and it's now one of the easiest planes I have to fly.

[SpiceMan]

Hi Spiceman,

Please describe "like a rock", did you get a "powered glide" or did it "nose in"?. The balance from your pictures looks good apart from the fact that it looks like you haven't got the model on point contacts but it might be that I don't understand your Jig. For little models like these I just stick pins in the wing tips and balance them across two hard back books stood upright.

In any case don't rush to remove the weights. The problem is that Guillows supply a ridiculously small prop for that series of kits, it really is crazy. A model that span should need something in the order of a 7" prop to fly with rubber. Also the rubber is pretty poor (little energy storage). You maybe are just underpowered?

The other thing to check is the decalage , (angle between wing and tailplane). Try some tabs on the tailplane trailing edge angled upwards, I use cut down post it notes to make temporary ones for trimming purposes.

I would also not remove all of the weight in one hit, take out 1 piece but put say 5g back in using clay or the stuff you use to hang posters as a temporary measure (we call it blu-tack here I don't know what you call it in the US). This is because if you go nose light your model will stall and could slide back onto its tail and that's an easy way to damage things.

I apologise if you know this stuff already!

Good luck!

Cheers

Andrew

Hi Phugoid ...
Please forgive me for being so slow in responding to your informative post.
When I said she flew "like a rock", what happened was, I hand launched her with 150 turns on the prop / rubber, and she quickly rolled slightly to the left, and then the nose dropped, sending her into a dive @ about 45 degrees. This was indicative of a combined "torque roll", and not enough air speed ... in the RC airplane world.
The balancer that I used is one used in the RC airplane world. It's a "Great Planes - C.G. Machine Airplane Balancer". It's hard to explain how it works, but there are 2 "support pads" with ball-cups on the under sides, which snap into balls attached to the long rods which are attached to the base. Each support pad has a "measuring scale" and verticle peg attached, which can be adjusted back and forth. So if the airplane plans call for a CG which is 30 mm back from LE ( like this 170 does ), the pointer on the support pad is set to 30 mm on the measuring scale, and then the airplane wings are placed on the support pads, with the verticle pegs resting on the wings LE. When the airplane is sitting level ... it's balanced.

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IMG_0821.JPG

IMG_0822.JPG

I think that low air speed was the main problem on the maiden, which makes me tend to agree with you, as you mentioned being "underpowered".
Thanks for the idea about using some "tabs on the tailplane trailing edge angled upwards". I'll have to try that. Also ... good point about taking too much weight out all at once. I'll try removing 2g's at a time, and see what happens.
Thanks for your good suggestions. You can probably tell that I'm "new" to the world of Free Flight.
Oh BTW ... I've discovered that there's actually a CLUB of rubber powered airplane flyers here in Phoenix. I plan to attend one of their meetings ASAP.

[SpiceMan]

Bravo! on your first flight attempt.

I agree with Andrew, you need little tabs on the elevator or bendable control surfaces. Trimming for a glide flight usually takes half a dozen little flights. If you have tall grass, use that for test glides. The decalage is very important. Many of the kits have zero degree decalage, when it should be about 3 degrees, negative. That's a fancy way of saying you probably need more UP elevator. (After studying your pictures, again. The model definitely needs UP elevator. The horizontal tail surface appears to be parallel with the underside of the wing. 0 degree angle difference.)

O.k., I'm going out on a limb on this:
Your C.G. leveling rig. If I understand things correctly you are balancing according to the underside of the wing. The model appears to be nose down in the rig. I think if you balance with the longitudinal axis of the fuselage level, you might be better off.

67 grams, I think is a bit heavy for that size model but, it still should perform decently. Definitely not brick style.

Hi Wildpig ...

Thanks for your comments also. Unfortunately, there's really no area that I know of that has "tall grass", however, the park where I fly does have grass. The tallness ( is that a word ? ) just depends on how often the city workers get around to cutting it.
I agree with you that this bird should not fly "brick style". I'll probably try more turns on the prop / rubber next time ( for more and longer air speed ). Kind of reluctant to wind her up too much too soon ... don't want to "break" her right away.

[SpiceMan]

Nice work on the spars- I'm trying much the same atm with my 900 series bird dog. Though I was doing it more to try and keep wing alignment correct on assembly.

Nice looking plane!

Hi stx44 ...

Thanks for your comment on the spars and the plane.
After installing the wings, I had to glue a "shim" in place to attach them, but I feel that connecting them together, added some extra rigidity to the wings. Sure don't want a wing to break off during a "hard landing".

[SpiceMan]

Well, I took the pretty bird to the park on Friday, for her maiden flight. Keep in mind that this is my FIRST balsa rubber powered kit airplane that I've ever taken to completion, and attempted to fly.
Well ... Bad news, and good news:
The Bad News is: She flew like a rock.
The Good News is: I did 2 flight attempts ( each with "hard landings" ) and nothing broke.
So my conclusion is that she is way too nose heavy, and I'll be removing one of the 7 gram weights from the cowl, before attempting the next flight.
I had a friend shoot a video of the ill-faded maiden attempt(s), and I intend to post it on YouTube after I finish that learning process. Hopefully, I'll be able to up-date you all with a link to the video, in the near future, if you'd be interested to get a good chuckle.
At any rate ... I'm having fun.

Sounds great that it flew.
Got me thinking of my first Guillows Cessna 150 rc flight. I had a slight mismatch in the wing incidences, and a slightly misaligned rudder. Of course the rudder misalignment direction added to the problem, as the right wing not only lifted more than the left, but the tail was forced to the left. It caused a really interesting sidewinder flight, where right turns were not possible and left turns tended to bank severely downward. That was one of those experiences where I learned how critical settings are. A slight correction of the wing panel and rudder placement, and it's now one of the easiest planes I have to fly.

Hi Bill ...

I totally agree with what you say about alignments and such. My RC planes have taught me many similar things too.

[Wildpig]

I've not built this particular kit but, similar ones. Gauging from the wingspan and weight:That model should glide about 25' to 30' feet when gently hand launched.

I wouldn't put any winds on the rubber for the first few trim flights. Without power it should glide straight ahead, with no rolling off to one side.

Did you put dihedral into the wings? I see from your balance rigging photos it appears that you did. Many of these kits have scale dihedral and then a more pronounced flying dihedral.

[Phugoid]

Hi Spiceman,

That is a really neat Jig! I understand it now - thanks for showing it. Yes it sounds like you might some right thrust although 150 turns isn't much, and the torque effect of that tiny prop will be relatively (compared to the span of the model) small. Having said that the Guillows rubber goes very "tight" with very few turns, it is not very stretchy, this may lead to the power burst and torque effect that you observed. To be honest I open the box and the rubber is the first thing I throw away!

The other problem with the Guillows kits are the plastic nose cones, they look good (scale) when compared to perhaps a sheeted nose but there is little chance of getting and accurate and repeatable thrust settings you can be it's a bit fiddly, there are a few threads by people like scigs30 and kittyfritters that show ways to overcome this.

Over on Widdogs Skyraider thread he lists a supplier over in the US for better props and rubber (super-sport). It might be worthwhile getting that sorted before proceeding....

Andrew