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Oct 21, 2016, 12:51 PM
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Canard location -- Alternate


This is what I meant about my alternative canard location. I also installed the original scale location brgs.; while placing its current location on the top side of the intake ducts, thus a distance above the wings.

Kurt Schroeder, one of the 2 original company test pilots involved, said the canard was 'in-plane'. I take that as in the same vertical plane as the wings.

Have yet to compare pitch sensitivity between the 2-locations. But I was thinking, the upper staggered location may give more laminar flow from the bottom of the canards to the top of the wings; while the 'in-plane' location has more chance for the turbulent air of the top of the canards to go directly on top of the wing root area. Cud this result in more pitch sensitivity?

I'm thinking Grumman & co made a more challenging canard location work. A quick review of other canard planes:

The Israeli Kifr, the Gripen, Euro-Fighter & the J-10 have significantly higher canards; the Rafale has less vertical distance. The Russians have them almost in-plane on the Su-30MKI & Su-47, both may be 'cause their origin from the Su-27. It is a puzzle to me, hence thought of direct comparison.

Phil
Last edited by Phil Lin; Oct 26, 2016 at 10:23 AM. Reason: add Eurofighter
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Oct 24, 2016, 12:18 PM
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Quote:
Originally Posted by jetset44
........ Looks like it flies well from gear, too.
Yes, the model took to the air with a short run on grass, as shown in the vid. And that was a still air day.

Should hav asked @jjr, here for details of his fixed gear design; instead of chewing on it for a bit. I know folks building here don't need details; but for those sitting on the fence, perhaps sharing my gear details can help get them to build. I'm sure others can come up with a better design too, See attached pix

I tried to use as much off shelf components as I cud find. So the nose gear had DuBro 3/32 OD nose gear steering pkg.

My wheels were the 'lite' version; 1.75" OD nose, 2" OD mains. .

A couple of details on the mains:
-- Used a lite ply sacrificial plate to mount the 1/8" music wire. Provided a short length of wire for torsional shock absorption. There is a box under the gear plate tying the fuse bottom to the wing underside. ((had glued 12k carbon fiber (c/f, 2 strips) on underside of wing across the fuse to absorb gear loads. Details?)).

-- The support box had 2 pieces 3/8" sq. basswood bearings, across; fanfold c/w 1/32-ply lining I-side. Also had cut-outs & used as a pull-box to allow disconnecting motor from Esc in case of repair.

Oh yes. My Esc is Velcro-ed to the inside vertical face of one intake air duct, for added cooling. This also makes it accessible when needed.

Phil
Oct 26, 2016, 02:00 PM
Park Jet Guru
jetset44's Avatar
Thread OP
Hi Phil,
Thanks for posting the details of your gear installation, looks good.

I thought you used a gyro given how smooth it was in flight. I got my X-29 fly acceptably without a gyro, but it was a handful and not very pleasant to fly. Adding the gyro transformed it into a pussycat and great fun to fly.

Interesting thoughts about the canard. Usually the vertical separation between the canard and wing has more do with getting max lift, not with affecting pitch control or pitch stability. The theory is that the canard tip vortex can energize the flow over the wing root at high alpha, allowing a higher angle of attack before stall. So designers test multiple heights (in either wind tunnel or CFD) to see what vertical separation yields the most lift at high alpha. This usually results in a canard mounted high above the wing so that the tip vortex is right over the top of the wing at high alpha. Too low and the vortex goes under the wing, too high and it goes too high over the wing. Why the X-29 went with an in-plane canard I don't know, but my hunch is it may have been due to the aerodynamics of the forward swept wing. I'd be interested to find out! And I'd be interested to see if you notice a difference on your model if you test it.

No need to send me any royalties for the plans, I just enjoy seeing folks use them. But thanks anyway!

Steve
Oct 30, 2016, 02:06 PM
Registered User
Quote:
Originally Posted by jetset44
Hi Phil,
..........
Interesting thoughts about the canard. Usually the vertical separation between the canard and wing has more do with getting max lift, not with affecting pitch control or pitch stability. The theory is that the canard tip vortex can energize the flow over the wing root at high alpha, allowing a higher angle of attack before stall. So designers test multiple heights (in either wind tunnel or CFD) to see what vertical separation yields the most lift at high alpha. This usually results in a canard mounted high above the wing so that the tip vortex is right over the top of the wing at high alpha. Too low and the vortex goes under the wing, too high and it goes too high over the wing. Why the X-29 went with an in-plane canard I don't know, but my hunch is it may have been due to the aerodynamics of the forward swept wing. I'd be interested to find out! And I'd be interested to see if you notice a difference on your model if you test it.

No need to send me any royalties for the plans, I just enjoy seeing folks use them. But thanks anyway!

Steve
Thanks for your generosity. There has been some talk on the forums re authors royalty. As the saying goes..."if only I had a buck for every....." But your willingness to share pro-Bono is sure appreciated.

Regarding a vortex generator above the wing, You mean something like this in attached Mirage 2000? Or more interesting the attached Eurofighter, the canard of which may not be generating the preferred conical vortex. The latter canard may be too far forward. I also suspect the Euros canards may be blocking a pilot's downward sight line; but perhaps alleviated by the latest sensor system?

I understand Grumman first introduced Leading Edge Extensions (LEX) on production F-5s; which grew in size with later variants & culminating with the curved ones on the early F-18's, to the huge ones on the F-18E/F's. The F-14's had a gloved LE which could also generate conical vortexes & close to size of those on the X-29.
Last edited by Phil Lin; May 13, 2017 at 09:23 PM. Reason: Add Grumman's LEX, clarify
Oct 30, 2016, 02:17 PM
Registered User
Perhaps I should post a couple of pixies to round out details of my gear addition. The mains & its support comes to about 3.5 ozs. The nose gear, its steering servo & birch ply half bulkhead c/w with trapezoidal 1/32 thick side ply reinforcement just over 2-ozs. My preference says they're worth the weight penalty.

Attached are the top & bottom wing view where carbon fiber supports were situated. May be beneficial to reinforce the bottom of the LEX with 0.75oz glass to tie things together. Seems water based polyurethane for the f/g don't ridge up at the edges as much as epoxy; though probably not as strong.

Phil
Last edited by Phil Lin; Oct 30, 2016 at 02:25 PM. Reason: Spelling
Oct 31, 2016, 11:00 PM
Registered User
I really need to continue expanding flight envelop & test turning off gyro to see if this model will fly now without it.

Hav figured out my programming error & am now able to switch gyro from 'normal' or rate control (blue indicator light) to no gyro (red indicator, was going to white mode before ). I hav also programmed the flaperon (camber control) c/w mixing some up canard. But our weather has been cold with cross wind lately; so I probably will not have progress to post for a while, unless we get a lucky change, or I get some more feedback what area folks are interest in.

Phil
Nov 01, 2016, 01:16 PM
Registered User
seeingeyegod's Avatar
ooh this is cool.
Nov 01, 2016, 10:43 PM
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Quote:
Originally Posted by seeingeyegod
ooh this is cool.
Thanks, Seeingeye!

I used my last supply of 6mm Depron for the flying surfaces too Will need to find a substitute.

Phil
Last edited by Phil Lin; Nov 05, 2016 at 10:35 PM. Reason: spelling
Sep 06, 2018, 05:00 PM
Keep calm and fly on
Nicksta4's Avatar
has anyone tried this with a 50mm or 64mm edf?
Oct 13, 2021, 01:29 PM
newbee, that is on 18-08-2012
it has been a while since the last post but i had the same question / plans to try this as an EDF (64mm) any thoughts?
Oct 16, 2021, 09:02 PM
Held by Grace
BDOG1's Avatar
Hey spike :
As far as thoughts about building this ( or any of the pusher park jets ) using a Edf
There is no reason why it wouldn’t work /fly as long as you maintain the same cg ,the plane doesn’t know or care what pushes it forward in flight .
Considerations would be having enough intake area to supply air to the fan and the extra weight of the Edf compared to the prop jet motor .
Over 10 years ago I built one of jettset’s
F-14 ‘s flying it first as a pusher and then changing it over to a Edf power using a
Stock Hyperflow fan - it flew fine

Later I upgraded it to a hotter motor and upped the speed and performance ,today’s Edf systems have far better performance than the early Edf’s I used.
Have fun and post your build !
Mike


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