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Apr 24, 2011, 07:01 AM
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davereap's Avatar
For the wing I usde a 4mm box section CF ..for the boom a 4mm round tube..

Ive just altered the vertical fin by chopping the bottom half away.. The turn remains poor so it definately needs a lot more dihedral..instead of the total 3" I used 5-6" will be better at this size...

I am going to try to bend my joint, but suspect I will wreck this model..then perhaps I will look at the mimi

Ive also just flown with a lighter reciever and a COG of 41% back at the root.. this has made it glide flatter and is about back near my limits as its gettin sensitive on the elevator
chopping the fin and altering the COG did not affect the nice straight launch..
I was surprised how straight my launches are on this one with a short boom..something's all right there anyway..or is it that I cant give it much power in the launch...

edit.... heavy bending with some creak and cracking sounds has increase the total dihedral to 5", it looks like one spar is breaking up so I will have to stop there while it will still fly...checked on a protractor gadget and its about a 15 degrees total in the middle..
Last edited by davereap; Apr 24, 2011 at 07:31 AM.
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Apr 24, 2011, 07:17 AM
Just call me crash for short
Quick61's Avatar
Not to bad at all. The DLG guys say that you should have equal surface (or as close as posable) above and below the boom. At least yours turns! the first attempt I made if you remember is it only turned left, due to the peg side being heaver than the right. From what I have learned so far, I think your conclusion of not enough dihedral is correct but it seems to turn OK, but then again I don't know if you were giving full stick or not? How hard would it be to cut the wing and add more dihedral? Or did you do what I do and build a nice sturdy brace on the spars and bury it in the wing? From the video it looked like you were SALing the not giving full rotation DL. Not that bad for SAL. The wing looks like it wants to fly fast, is that correct?
Apr 24, 2011, 08:09 AM
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davereap's Avatar
Thats a B***** ive chopped the tail already...
yes SAL is about all I can do ...and even on that I am poor..
yes the spar is burried and has a sturdy bit of piano wire epoxied in at the joint, so a bother to bend, however, I have managed to bend it and get some extra dihedral, but I am sure one spar is now damaged near the root..
It feels strong enough however for my weak throws
again yes, it flies fairly fast, and more so with a more forward COG..some of the speed is also down to its weight.. A weight saving exercise would improve the float..or an increase in the wing span/area to lower the wing loading would also work..

As it is it needs to loose about 1.5oz to compare or compete with the Mimi mentioned earlier.. difficult to acheive but not impossible, it is built fairly/over strong, with all doubled laminations etc for the fuz and tail. even the weight of the wing might be reduced by having some of the middle layers with air gaps rather than all solid layers and the CF could be a tube rather than a box etc.....It needs more thought...but thats what a prototype is for, getting it correct..
Last edited by davereap; Apr 24, 2011 at 08:23 AM.
Apr 24, 2011, 08:43 AM
Just call me crash for short
Quick61's Avatar
Got ya. I think J.P.F.'s comment is a good one on the wing tips. Thinking about this, maybe grab up a sanding block and taking the last 1/4 or 1/5 wing tips and sand them down from a KFm9 to a KFm2? Taper off the 35% and 75% steps to where you end up with a KFm2 wing tip? If the spar is cracked but still holding after this next run, maybe give it a try? Just thinking out loud here. And for poor SAL's, I don't think I would be that disappointed with your results as a first go. Fine tunning a bit and it should be a good one. Your KFm9 continues to impress.
Apr 24, 2011, 08:57 AM
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davereap's Avatar
Yes I think it makes a good glider wing for our simple builds...
I just had another fly... The model is turning much easier with a total of 5" dihedral on a 1meter span model.. this was almost exactly the 7 degrees/panel that jetplane said...so there you go..that works..thanks
Launches are slowly improving, and as its still tracking nice and straight, I dont think there is any problem with heavy tips.. but I am still only managing about 1/3 the height some of the flyers can get...still thats down to me not the models, I am total rubbish at the launch..

With a lighter build and a fit launcher I think this KFm9 is definately worth a go...
Last edited by davereap; Apr 24, 2011 at 09:16 AM.
Apr 24, 2011, 09:31 AM
Curiouser and curiouser
Kokopeli's Avatar
Quote:
Originally Posted by Cybernaught
..........
gpw,
"Those who can, do. Those who cannot, teach. Those who cannot teach, administrate."
I would like to add: "Those who cannot administrate, run for public office."
.........
Well, I like to think that I am very capable at "doing" but moved to teaching, some for altruistic reasons and some because I thought that I could get away from the petty politics - WRONG! i think it was Kissinger that said " the reason politics in academia is so vicious is because there is ABSOLUTELY NOTHING at stake. All the rest I agree with
I will use the KF wings instead if reinforcing a wing with some weight that does nothing for performance. In skimming these posts I didn't see anyone mention THAT attribute

Walt
Apr 24, 2011, 11:12 AM
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Dickeroo's Avatar
Quote:
Originally Posted by wjbite
Well, I like to think that I am very capable at "doing" but moved to teaching, some for altruistic reasons and some because I thought that I could get away from the petty politics - WRONG! i think it was Kissinger that said " the reason politics in academia is so vicious is because there is ABSOLUTELY NOTHING at stake. All the rest I agree with
I will use the KF wings instead if reinforcing a wing with some weight that does nothing for performance. In skimming these posts I didn't see anyone mention THAT attribute

Walt
Walt... sadly politics is everywhere... academia, medicine, science, business and of course... politics.

The RC Groups stands apart from all that rubbish because the people here focus on sharing information freely and are all very supportive of each other. You can't find a more creative and friendly group of people anywhere. The world could take some lessons from the RC people on how to improve the quality of life for all of us.

– Dick
Apr 24, 2011, 11:34 AM
Just call me crash for short
Quick61's Avatar
Quote:
Originally Posted by wjbite
I will use the KF wings instead if reinforcing a wing with some weight that does nothing for performance. In skimming these posts I didn't see anyone mention THAT attribute

Walt
Well, Walt, It does not get mentioned much I think because that is one of the things that has just become a given, perhaps falling 'close' to a self evident truth. Kind of like disusing how wet water is...... Then again, maybe it should be mentioned more as there are new people becoming acquainted with the KF step most every day.
Apr 24, 2011, 11:42 AM
Just call me crash for short
Quick61's Avatar
Quote:
Originally Posted by Dickeroo
Walt... sadly politics is everywhere... academia, medicine, science, business and of course... politics.

The RC Groups stands apart from all that rubbish because the people here focus on sharing information freely and are all very supportive of each other. You can't find a more creative and friendly group of people anywhere. The world could take some lessons from the RC people on how to improve the quality of life for all of us.

– Dick
You are so right Dick, and one of the many reasons I enjoy this group so much. A good escape from the politics and a good place to participate in Open Source information.
Apr 24, 2011, 01:06 PM
Registered User
davereap's Avatar
Quote:
Originally Posted by Dickeroo
Walt... sadly politics is everywhere... academia, medicine, science, business and of course... politics.
– Dick
I dont know who are worse, the poiticians..or us idiots, who put up with all their c***..

come on now show us what you are building or tell us your next project...
Apr 24, 2011, 03:38 PM
Registered User
rcta15's Avatar
Quote:
Originally Posted by davereap
I dont know who are worse, the poiticians..or us idiots, who put up with all their c***..

come on now show us what you are building or tell us your next project...
was going to try ur twizzel dave but then i saw the pitcherons (need more detailed info for me lol) and as i dont have 2mm depron can i use 3mm instead?
RCT
Apr 24, 2011, 03:57 PM
Just call me crash for short
Quick61's Avatar
Quote:
Originally Posted by rcta15
was going to try ur twizzel dave but then i saw the pitcherons (need more detailed info for me lol) and as i dont have 2mm depron can i use 3mm instead?
RCT
https://www.rcgroups.com/forums/show...hlight=twizzle

for the build thread on the Twizzle, as for the 3mm... Dave will be the one to get down to brass tacks on that. For the bystanders answer, you would need to scale up a bit to keep the thickness to cord ratio, but Dave is the one that can give you all the details on it. The KFm9 is his baby..... and a beautiful one at that
Apr 24, 2011, 04:14 PM
flyin' fool
goldguy's Avatar
Quote:
Originally Posted by Dickeroo
Walt... sadly politics is everywhere... academia, medicine, science, business and of course... politics.– Dick
Now you've got toy airplanes and the FAA having it out in the political arena.

So, add that one to the list.
Apr 24, 2011, 04:48 PM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Whenever the bureaucrats get involved in our pastimes , you know it's going to be Trouble ... Look what they did to our Free TV ...
Latest blog entry: Lost plans
Apr 24, 2011, 07:55 PM
Onward through the fog.
Cybernaught's Avatar
Dave,
That looks very nice. The glide is pretty flat and you only need smooth turns to keep her from losing altitude too quickly.

One thought for you. (Call me crazy if you want.) If I were going to get into gliders again I'd try to make an Atlatl for launching. That's been knocking around in my head for a long time. Drop the handle or use a wrist strap to get both hands on the TX. Less huffing and puffing and longer flights.

atl-atl, an ancient weapon (0 min 50 sec)

Forget the spear and think "Glider"...


Steve.


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