Yak 23 build blog.....it begins.....

[Dusty]

Tony sorry for the "model that looks good and wont fly?"

 

I idle the fan on the bungee and as soon as the model is released simultaneously hit full power so it should be airborne within 3-4m leaving the bungee well behind! Its a art but get the model flying before the bungee. Cant see a problem with you model externaly. Is it not worth shipping it off to Ton or someone in the UK to have a look at it and get it flying, postage might save a complete rightoff? The airframe is only going to get heavier but the other parts are going like the fan and motor probably! Cant you loose the amp hog WB motor and put a lighter setup in? Put the WB in a Jpower AMX or A7 and thrash some foam about before your balsa model that is nice and scale.

 

Perservering for you buddy!

[kiwi g]

Well theres lots of good advice here..looking at the video I would say that cog is rearward. ,

A little tip about launching,    Dont run and biff, ... You will get a more effective launch with a good level throw., I have seen guys run to launch and upon throwing almost stall the aircraft. running usually causes bad attitude take offs.  if the launcher feels he needs to run , cancel the throw and let the plane lift from his hand,

EDFs should always launch level and at there own speed,.There is a theory of the launch being to fast and stalling the fan ,giving an effect of a lot of drag on the front of the aircraft , not your problem here tho.

 as has been said check tow hook position. 

I wouldnt be too concerned about thrust vectoring at this stage  because the stalling is too agressive and immediate.

Do you have any really long grass around that you could launch at 1/3 throttle into ,test glide, trim, remember like we use too do with free flight aircraft before everyone became technical experts. 

 

Keep trying tony youve made a great job of this and deserve the rewards.

[TonyS]

Hi Guys,

Thanks for the responses. All very welcome - it is getting a little frustrating.

I like the ideas though....

Firstly, the bungee hook position is good so we can discount that (about 3cm from the nose!! )

I like the idea of a throttle off bungee launch to test glide. Also I think there may be something to the tail incidence which looks OK but heck,.. something is causing the nose-up. 

I checked the CG about a dozen times before this launch because of the problems I'd had before so I'm sure that it's not too far back. 

 

I wholeheartedly agree with kiwi g about the running hand launch. Every one I've ever seen the plane is basically chucked from standstill after a pointless jog. There's a You-Tube video of someone hand launching a Funjet Ultra the same way.. Nuts, as the stock Funjet can be hand launched from standstill... 

There may also be something in the WB motor being too powerful but I'm going to re-build as is then try the options above first. I'm guessing this re-build will take a bit of time and patience!! - It's like performing keyhole surgery as much of the repair has to be done through the battery hatch.. 

[David E]

Do double check the elevator direction! Hope the rebuild proves easier than expected. To look on the bright side, you'll have great repair skills when you're done! Best approach has to be to rule out possible causes so a glide test followed by bungee no-power launch would be my approach. Hope you can sim it down quickly.

[TonyS]

Recently re-enthused and having had a mad few days repairing and fettling everything I could get my mitts on I'm back to the Yak. Nose off, new nose cut and on, next the battery bay rebuild, a new intake tube and a novel solution for supporting the enormous weight of the battery in the event of a mis-hap. I'm going to inject expanding foam into the fuse in the area around and under the battery tray. When it expands and sets it should provide a nice, solid support for the battery and hopefully prevent it crashing through the intake tube again...

Given I had to use some lead to correct the CG  after the first failed flights, I figure that swapping lead for useful foam is a good trade.

Progress:

Getting good at this keyhole surgery - repairing the interior of the fuse through the nose and the battery bay access!   

[Ton van Munsteren]

Tony,

 

Super to see your all fired up again on the YAK23.

 

Still kinda curious where you had the CG and if it was tail heavy with the maiden attemts.

 

Ton 

[David E]

Looks like you're getting good at this repairing business! Good skills to have

 

Hope this time round it flies beautifully. I know you'll get there eventually with enough persistance.

[propogandhi]

Well with your new found enthusiasm for the Yak it seems like a ideal time for me to start my Yak 23 build, so I hope you don't mind me post here on your thread with my progress. I've been keen to build this model ever since it was first released back in the time before lipo's and so far a really am enjoying it. Interestingly I've found a few things that differ to the plan and was wondering if you found the same:
 
1) On the plan for the center Rib (R0), am I meant to have 1 of these or two? The plan looks to ask for x2, but I only have one.
 
2) My F3 fuzz former was cut from 2mm Ply, not the 2mm balsa as it shows on the plan and in the instructions, maybe this is an upgrade?
 

3) Lastly my fuzz crutch was made up from 4 separate pieces that needed gluing together, not 2 as shown.

 

4) I didn't have any PVC sheet for the rear ducting in my box!

 
Glad to see your getting back into it Tony, and I like your expanding foam idea. So if you don't mind, here's mine:
 

All set a ready to start. Not much wood in the box, I guess thats why the model is so light!

 

 

Setting the lower formers and aligning Sunday night

 

Last nights efforts.

 

prop.

 

Edited By propogandhi on 12/10/2010 11:40:27

[propogandhi]

A quick question for you both (Tony/Ton), with the paper intake duct, is there meant to be a template anywhere? The only template I can see on the plan is for the exhaust duct/rear ducting. Am I just supposed to roll the entire roll of paper in the front ducting and glue it? Also can I ask how you gents glues yours in in the first place?

 

 

prop.

[TonyS]

Hi Prop, Sorry I've been quiet. Currently stuck on a boat off Pwllheli so signal dodgy. Not sure about the rib. The paper tube doesn't have a template. The only thing is to ensure that you paint it before rolling and make sure it's big enough that it won't collapse under the suction if the edf is fairly powerful. I glued it around the fuselage formers to give it added strength. If you're going down the lipo route don't forget the need to mod a battery bay. Took me a little while to get it right so that it was big enough to take the battery but not too big to foul the tube. Watching with interest but may not be able to join in until Friday! T

[Ton van Munsteren]

Hi Prop,

 

No there is no template needed, roll the paper to a tube and slide it in the formers.

 

Gleu it and then cut it to length, for me that was much easier than working with a template.

 

The link below includes foto's of the prototype YAK.

What I will do is I will make a gallery with all the pics I have on the YAK hopefully they can be of good use to you.

http://www.modelbouwforum.nl/forums/edf-forum/1238-yak-23-flora.html

 

Keep on going I will follow your every step.

 

Ton

[propogandhi]

Hey Ton, thanks for that, those photo's in the link will come in useful too.

 

Can you offer any feedback on the other problems I found, from my earlier post please?

 

 

prop.

[propogandhi]

Thanks Tony, so I should use the entire sheet of card supplied for the intake tube yes? Also I've tested it rolled up within the formers. When I try and open the roll out so it is tight in the formers, there are some points where it does have complete contact, between the card and the formers, if you see what I mean. Its only a few very small gaps here and then, but at the moment, when rolled out, the tube doesn't make ull contact with all formers (formers 1-4).

 

Hope this makes sense. I'm sure it will be fine once I do it for real. I may be able to glue the card ducting in, then make my battery access too. I'd ideally like to plank the bottom of the fuzz before I remove it from the board, and as I'm only using 3s lipo, I won't need to increase the depth of the battery bay, but I am considering opening out F2, and making provisions for the lipo to be able to slide a little further forward...time will tell.

 

 

thanks gents,

 

 

prop.

[TonyS]

Hi Prop, From memory I didnt use all the paper. I did have to get inventive to tape the internal seam. I used my clear packing tape and a ruler to push a piece in and stick it down. Worked bur was fiddly. T

[propogandhi]

Sorry I didn't mean the whole length, I can see that I'll need to trim that down once its dried in place, I meant the width. Your tape idea sounds ideal, I was thinking of using super glue, but that might well end up being a little too messy.

 

 

prop,

[Ton van Munsteren]

Hi Prop,

 

I designed the model some time ago and also the second model I build for testing the kit was not long after that.

So I will try to answere your questions when I can, but going a long the way Rob (mr RBC ) had made some mods to the kit that Iam not aware of.

1) On the plan for the center Rib (R0), am I meant to have 1 of these or two? The plan looks to ask for x2, but I only have one.

Iam not sure but I would think that this one would be thicker than the rest, try it in the slot if there is space left then there should be two ribs.

 

2) My F3 fuzz former was cut from 2mm Ply, not the 2mm balsa as it shows on the plan and in the instructions, maybe this is an upgrade?
Yes that would be a upgrade because spocken to Rob some time ago, he told me that he had finaly found liteply also in 2mm and that would be of some good use in the kits.

 
3) Lastly my fuzz crutch was made up from 4 separate pieces that needed gluing together, not 2 as shown.

That would be a mod that has been done to have the box size a little bit smaller then earlier. Some times the first box used for a kit is not fore sale anymore and you have to switch to a different size. Can think of any other reason.

 

4) I didn't have any PVC sheet for the rear ducting in my box!
Send Rob a email Iam not sure about that by I gessthere should be PVC in the kit for the rear ducting.

 

I hope that answer the question.

 

Ton 

[propogandhi]

Thanks Ton for the reply, glad its all cleared up now. I guess I can use any clear PVC sheet of a similar thinkness. I won't be able to work on the Yak until the weekend now as the workshop also doubles up as a guest room, and, well, we have guests staying!

 

prop.

[propogandhi]

Some progress, my first time planking, so I'm taking it slow, but this is the results of my weekends efforts, and I still have the other side to do.  I reinforced the hook area with some carbon fiber toe. Has greatly improved the strength of the area, well at least I hope it has...seems to have though. The fuzz should be sheeted by the end of the week.

 

I'm trying to find a LHS that stocks 4mm sheet too, but not having much luck, they only seem to have imperial sized sheet. I'd like to replace the supplied 4mm sheet tail parts, the balsa is a bit too hard for my liking, and I think it would be better all round to use lighter/softer grade wood in this area.

 

prop.

 

 

 

[propogandhi]

Hello all, unfortunately, due to other models on the horizon and lack of time, I've decided to sell the model on. Therefore the kit is on ebay if anybody might be interested. Tony, how about a replacement for your 1st model

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=230572262099

 

 

prop.

[TonyS]

Hi Prop,

What a shame. I understand what you mean by a lack of time though - something that's haunting me at the moment.

My first model is going strong, all fixed up and ready to fly...again. I'm just waiting for some fine weather and for the new grass strip at the back of the house to grow!

I have to say, it's tempting though. I know all the mistakes I made the first time around so could make a first class job this time. I'm beginning to think that most of my problems were from overpowering the thing with the Hoffman Wild Beast motor so next time could go with something less insane... My problem is I can't resist temptation...

Keep us posted with your other projects and I'll see what's left in the piggy bank.

T 

[jan A.]

Hi all,

 

I'm joining from france so excuses for the spelling

 

After reading a bit about the rbc kits I found this thread and dicided to go with the yak23.

 too bad for propaghandi for I saw his post too late

 

some differences in the kit though, many pârts have holes cut out to save weight, no probs there,

It was a calm weekend on the job so managed to get a lot a work done, here is where I am so far . bare in mind this is my first balsa kit, after some arf's and some scratch projects. But I enjoy building as much as flying so why not take the jump. planking is a pain in the *ss, probably due to lack of experience.

 

I cannot decide wether to go with glassing it, did it once before, did not like it, or using oracover

[TonyS]

Hi Jan,

Welcome,

No worries with the spelling - you should see me writing in French!!

I'd agree about the planking, but it's worth taking your time as you'll notice every defect when you come to cover it.

I'd recommend glassing with light glass cloth and a water-based glassing product like Poly-C or it's equivalent. You'll be staggered by how easy it is to use - it doesn't smell and it really is tough. I'm a real convert - I glass everything with it these days - even my ARTF foam models. Just glassed the fuselage on a Funjet Ultra! If you want to give it a go and need any help just shout.

My Yak had a few issues on its maiden flights. It took a real bashing but has now been fully rebuilt and is only awaiting a final re-paint before waiting for a bright dry weekend. 

Keep us updated on your progress and some video of it flying would be brilliant.

Looks really good so far.

T 

 

[jan A.]

Hi,

 

did some more planking today, almost done, and some work on the battery bay. i'll be placing the batt on its side, making for a long narrow hatch and hopefully conserving the line of the fuse.

 I'm going for a less powerfull setup (and hopefully lighter) set up, about the same as my f20 (witch is @1200gr and more than enough speed to be a challenge) this will be a het6904 fan, HK 60 amp esc, 3450kv outrunner (75gr/14$ battery either 300 or 3700 4s1p depending on the ballast needed

 

Saw the your vid today, and what can I say, I'm not looking forward to my first flight :s  you'll get it right. I do have the habbit only to hit the throttle after the bungee cord detached from the plane, (so after achieving flight) but I'm also going with a CoG prob

Jan

[jan A.]

ok,

 

did the wings this week, and I dont like

doing those, so many ways to screw up. they looked very bad for a log time, but came out fine in the end Managed to destroy the 1.5mm sheets for the wings, so I did the upper sheeting with 2mm sheets lying around. can only be stronger.

the construction of the duct housing underneeth was quite a fiddly job.

 

430 gr so far, but still n

eed to do the tail, sheeting underneath and covering wich will be oracover for this one, I shall use fiberglass on the next (f9f panter maybe)

 

Tony , when will your next take off be? please make a vid.

 

 

finally its lookig like a plane, not a canoe

more updates as work progresses

 

cheers

 

Jan

[TonyS]

Looking very good Jan.

Funny your last comment as mine looks like a plane but flies like a canoe.

 

I'm looking forward to the next flight too. I really must get my act together.

Keep going.

Tony