sensei

Has anyone stripped the covering on the the 50 cc Yak and placed it on a diet.

T. Bob

My Feedback: (9)

Seems like a lot of work for not much gain.
They are nice looking planes why would you strip it?

sensei

Hello T .Bob

I agree, the covering job was one of the best I have seen yet, however it would have been impossible to remove the 17 ounces of fat from the fuselage without removing the covering first. I will send more pictures of the development stages.

DENNIS C

My Feedback: (99)

Judging by the 1 st picture.....i dont see where your going to loose 17 oz's..unless you did it already.

Does the turtle deck come off

sensei

Your right, the weight has already been removed, in addition there is 4 oz's removed from the tail feathers, 2 oz's from the engine cowling, 1.9 oz's on all the aluminum hardware including engine bolts, 8 oz's on the carbon gear, wing tube and Kavan wheels, and as you can see the canopy has been trimmed about as far as you can go. I did remove the turtle deck so I could remove the plywood top-cap. I have not started on weight reduction in the wings just yet.

Note: all weight comparisons were performed after the covering had been removed from the airframe.

sweetpea01

My Feedback: (10)

Why......Hopefully your lightend bird doesn't fall apart from vibration

sensei

If you had ever owned or flown an aerobatic aircraft this size or larger with a close to 20 oz. wing loading; you would know the reason why....... Generally speaking the only R/C aircraft I have seen fall apart in the last 30 years have been due to flutter, poor bond lines and or glue joints, along with the only thing that could cause destructive vibration, and that is an in-properly balanced propeller. So I don't really see that as an issue. From what I can see in most of the posts about this airplane many of the guys are purchasing cans for the engines to get more power for those up lines and 3D maneuvers. Don't get me wrong; I'm always for more power, but in this case power is not an antidote for wing loading issues, in fact if the overall weight goes low enough the power to weight loading could be much better than running a pipe which is heavier than the stock muffler, hence adding to the weight problem in the first place.

sweetpea01

My Feedback: (10)

I see your point.........but there's something to structural integrity and weight.

sensei

[quote]ORIGINAL: sweetpea01

I see your point.........but there's something to structural integrity and weight.
[/quote

I couldn't agree with you more, The higher the weight, the higher the flight loads. There is an old saying that we used many years ago out at the NASA: Dryden Flight Research Facility in California, it goes something like this, "make the fittings big and engineer the hell out of the upholstery" What that means in this scenario is leave the well thought out spar carry throughs and massive longerons alone and trim the fat everywhere else, it's that simple.

sensei

Here is a couple of weight shots of the entire aircraft with the exception of covering on the fuselage, tail feather and 5" spinner. I will still strip the wings & ailerons and place them on a strict diet.

40%plane

My Feedback: (1)

HEY SENSEI,
LOOKS LIKE YOUR DOING A GREAT JOB. ANY CHANCE WE CAN GET A DATE AND LOCATION AS TO WHERE YOU MIGHT BE FLYING THAT 70% IN THE BACKGROUND AT.

MIKE

sensei

Thanks for the complement Mike. The Staudacher will probably never fly as long as I live, My attorney's tell me I have nothing to gain by flying it, and everything to lose if something goes wrong.

Sincerely
Bob Sawyer

40%plane

My Feedback: (1)

Sorry to hear about not being able to fly it at all, but hey good work on the yak, keep us posted.

Mike

sensei

Well, looks like the only way to get that 16 ozs. off the wings is, you got it, 1 lb. density foam cores and competition grade balsa skins, anyways, here we go.[X(]

T. Bob

My Feedback: (9)

Your kidding???

sensei

Hello T.bob,

No, I'm not kidding, the target weight for this project is not to exceed a completed dry weight of 13.5 lbs. I figure if your going to step up to the plate; then swing for the fence. The last project was a 1/3 scale Lanier Laser kit 96" span, Finished dry weight was 15.5 lbs with a DA 50cc with stock muffler, The flight characteristics...... well ever flown a shock flyer?

hpergm

Very impressive!

Of course, this whole thing does require some serious time commitment (possibly beating the ARF mentality). Naaah, what the heck, I'm jealous - I admit it.

Go for it and let us know. I have done some of the lightening mods myself (I think you've followed the other thread) and its close to 17-17.5lbs (I'll know exactly as soon as I get a decent 30lbs scale). Have you noticed any rigidity issues by removing the wood of the fuz (i.e does the rear fuz flex now withoutthe backbone plate..)?

T. Bob

My Feedback: (9)

sensei

May be you should take up scratch building.

I think it would be less time and aggravation.

sensei

Hello Hypergm,

Thank you for the complement. When I removed the turtle deck to get to the plate, it became very flexible, but that was to be expected, I have seen this many times. Once the turtle deck was bonded back in place, the rigidity was completely back in-tacked, and when the covering is replaced it will only get more rigid.

sensei

Hello T.Bob,

Scratch building, been there done that many long years ago, and this is a "HOBBY", it really doesn't matter to me how long it takes as long as I reach my objective, and if this hobby aggravated me; I would probable take to a different hobby. The only thing I was disappointed about was I could not find a 50cc Yak that was not an ARF; when in-fact I wanted a kit. Now don't get me wrong I like ARFs as well as anyone and I know from a business stand point it would cost nearly as much or more to produce a kit that would have to be sold for less because it's not an ARF. However, it just would have been more fun to build from a kit.

hpergm

Sensei, how about the tail feathers (rigidity wise)?

4oz losses seem a lot, and if true I will order a spare set of stabs and do the same. Weight reduction will then be even more, since I may be able to ditch the metal spinner and go with a CF (which I have but cannot achieve balance with[>:]).

newshoundaussie

I know this does not save weight, but move the engine ahead abit for balance this has to be the easiest scale plane to do this on!

sensei

Hello Hypergm,

Well, I started by placing small penetrations in the tail feathers, this was so I could gage the 50% of desired skin thickness removal by using a 16" sanding block fitted with #80 grit sand paper. Next I did a layout and skeleton operation to the control surfaces only. NOTE: I did thin the stabilizers, but I would not recommend placing any penetrations in these items. Next I replace the horizontal aluminum anti rotation pin with a .250" carbon tube permanently glued into the fuse, the weight saving on the tube was over half a ounce alone. The control surfaces became fairly flexible when this operation was completed and once again when the covering is replaced, the rigidity will be back in-tacked. Here are a couple of pictures, one the new battery and regulator location compared to stock. This configuration is for proper C/G purposes, the new location added 10 grams to the structure and doubles as a shear web across the top of the longerons. The other picture is of the carbon tube modification.

PS: There is also one picture of the new wing progress, I should have more to show by next week.

sensei

Here are a couple more pictures of the new wing construction with the cores fully cut and the phenolic tube sockets installed. The current weight per wing half is 6.7 ozs. I still need to perform additional weight reduction on these cores prior to sheeting the wings, I should be able to get that completed this week, and maybe get them sheeted this coming weekend.

DENNIS C

My Feedback: (99)

This is great info here sensei. how did you cut the hole in the core for the wing tube.

Are you going to post picture's on how your going to lighten the foam core's also ?