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Author Topic: Home-made Jets  (Read 2702 times)
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Mike Taylor
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« on: February 23, 2008, 04:16:11 PM »

I got ahold of one of Mike Cross's 10mm motor / 30 mm EDF fan units to test. It worked so well, I bought a production motor to go with it. Mike makes the motor and winds it for 2-cell 30 mm EDFs. They come balanced, and the first one has several hours of run time on it. It makes a light weight, powerful propulsion system.

I put it in a depron F-102 airframe with Falcon Breeze radio, YG4BL ESC, a 2 x 250 mah battery. AUW was 52 grams, and the EDF unit made 54 grams of thrust. It was 'sprightly', to say the least. There is a link to a short video of it flying here: http://www.rcgroups.com/forums/showthread.php?t=776716
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Mike Taylor
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« Reply #1 on: February 23, 2008, 04:20:05 PM »

This lead to a full fuselage version with molded CF duct work and a built-up foam wing. The 14" model came in at a portly 70 grams. Several nose changes got thrust back up and the model flew stabily and predictably, but without the vertical performance...
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Mike Taylor
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« Reply #2 on: February 23, 2008, 04:21:59 PM »

The second unit is now sitting in a Shinden, but the ultimate turbojet intention. I will post some photos when the wife returns with the camera...
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Spidergray
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« Reply #3 on: February 23, 2008, 11:00:11 PM »

Interesting small jet Mike. Be interesting to see it fly. I noticed it on the RC Groups threads I have had a long time interest in the F-102 Was stationed at Perin AFB in 1961 where the F102 and F-86Ds were used for Advanced Interseptor Training, The also had the TF-102 side by side trainer there. The single seater were a pretty plane but the 2 seater TF-102 was not as pretty in my humble opinion.

Don't know if you were in Ventura county when Oxnard AFB was open and they were flying the F-106B there. They were fun to watch scramble out but not nice late at night in North Oxnard during one of the night time scrambles over your house. We sure had a lot of different planes at OAFB when it was an ADC base- F-51Ds, F-94Cs, F-89Ds, F-101Bs, and the F-106Bs. OAFB and Pt. Mugu sure put a lot of interesting planes in the air over Ventura County.
« Last Edit: March 07, 2008, 08:44:19 AM by Spidergray » Logged
Mike Taylor
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« Reply #4 on: February 24, 2008, 01:32:11 AM »

Yep, I was here, on the same piece of ground, as a matter of fact. Camarillo's Scorpions are named for the missiles the f-80s(?) carried when the school was built. When the wind was right, the approach to OAFB was over our house in the Heights. It was 2-story, long and yellow, and stood on the side of a barranca that was aimed just right. The f-106s would go knife-edge and fall out of the sky, following the barranca. You could see the pilots' faces and count rivets. It was very cool. We used to see the Navy's SkyRays, another favorite. See: http://www.rcgroups.com/forums/showthread.php?t=740150 for a 2/3s ounce SkyRay...
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« Reply #5 on: February 24, 2008, 10:09:57 AM »

Yes it was an interesting time and the planes did fly lower than than they do now. Mike the F-89D was called the Scorpion maybe that was what the school was named for. I too liked the early navy jets we saw in the early days F3D Skynights, F-3H Demons, F9Fs Panthers, F9F8s Cougars, A3s, A4s, A6s, F4Ds and F4s just to name a few. Saw the TFX (short lived) and F14 both go through testing at Mugu amoung others.I also enjoyed the Drones that they flew out of Pt Mugu TBF/TBMs, F6Fs painted orange they also would fly low over the area and you could see no pilots in the planes. As I remember they started putting dummies in the planes to ease some of the complaints they got. I guess one of the most interesting events was the F-89D vs runaway F6F drone engagement do you remember that?-
http://www.freerepublic.com/focus/f-vetscor/1511880/posts
http://www.abovetopsecret.com/forum/thread38422/pg1
The Navy and the Air Force both got a black eye over that incident.

Lots of war stories about times in Ventura County.
Was in the Boy Scouts in Camarillo and the we were invited to the day the transition took place from F94Cs to F89Ds at OAFB. What a great day that was for me as a kid. Got more stories that I will save for a later time.
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Mike Taylor
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« Reply #6 on: February 24, 2008, 10:32:40 AM »

Here's a peek at a jet the didn't fly out of CamAir or Mugu... The jet version of the J7W1 Shinden. It is meant as a test platform to figure out canards. By using 'Y' cables to couple the 4 servos going onto it, I can mix/isolate a number of different control set-ups without changing more than the harness... I don't usually paint models before they are successfully flown, but losing the contest by 1 vote to a good looking paper-mache model that didn't fly taught me my beans on that!
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« Reply #7 on: February 26, 2008, 08:45:52 AM »

Hi Mike,

Your Shinden looks interesting, have you flown it yet?
is it another 30mm DF powered plane?
Sure looks like a small plane.

Gary
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Mike Taylor
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« Reply #8 on: February 26, 2008, 10:20:31 AM »

Nope, I haven't flown it yet. The radio is in, ready to go, but the wind is up this morning. I hope it will die down so I can do some trimming glide testing today. The fully colored model without gear was a sort of dig at another forum where I was in a contest, and the winning model looked great but didn't fly.

It is a 30 mm EDF, WS 18 1/2", weight 60-some grams. I want to test the best way to set it up and control it, hence the profile model. Here it is with gear installed...
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Mike Taylor
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« Reply #9 on: February 27, 2008, 01:21:12 AM »

Oh, man, that sucked! Couldn't get anything approaching a glide out of it. I'm repairing the canard, and started moving the battery back, and thinking about reshaping the wing airfoil. Something along the lines of a Horten wing, with reflex and tip wash-out. I'm glad I didn't spend a lot of time on this...

« Last Edit: February 27, 2008, 01:26:44 AM by Mike Taylor » Logged
Dan G.
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« Reply #10 on: February 27, 2008, 11:18:16 PM »

Sympathies!  Courage.
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Mike Taylor
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« Reply #11 on: February 28, 2008, 01:42:18 AM »

I rebuilt the canard a little larger, moved the battery back, and got an ROG today. More tweaking is due, but at least it has been airborne. It seems quite stabile and once it is trimmed correctly should be an interesting flier.
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« Reply #12 on: February 28, 2008, 09:09:47 AM »

Good work on this preliminary design Mike, keep up the R&D and hope that your efforts will make for a nice built up airplane later.
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« Reply #13 on: February 28, 2008, 09:16:24 AM »

Hi Mike,

It looks like the plane will make a great test bed to work with for you. Working through the details as Dan and Sundance mentioned will take some Courage and Effort and I add ability, looks like you have that covered. Hang in there Mike will be following your Shinden adventures.

Been fighting the flu bug battle here looking forward to getting over this. Have enjoyed watching the forum on my laptop, but may have gotten a little screwed up with my posts/typing I am sure.

Gary
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Mike Taylor
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« Reply #14 on: March 01, 2008, 11:57:19 AM »

I've made more test/trimming flights, and have got a couple of figure 8's out of it. The canard seems to be prone to stalling with resultant loss of control. I am cutting the fan loose to give a little down thrust to see if that will help keep the nose up. It is very stabile in flight and ROGs are pretty cool, and after weighing some alternate materials, I think a serious reduction of weight is possible. I have broken the canrds off a number of times, but the rest of the airframe seems over-built, and I believe I can easily shave 10 grams off it just be forming a fuselage shell and dropping 1 servo. A built-up wing would also add lift with little (if any) weight addition, and knock-off canards will be a welcome addition.
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Dan G.
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« Reply #15 on: March 01, 2008, 08:38:25 PM »

I am curious -- what sort of C.G. do you run with canards?

Dan G.
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Mike Taylor
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« Reply #16 on: March 02, 2008, 03:25:46 AM »

The CG is in between the two surfaces. With this design, the CG calculates to at the LE of the main wing to 1/2" in front of it. The plans show it (on the FF model) as being at the LE, and this calcualtor (http://sky.prohosting.com/air2/cg_canard.htm) suggests slightly farther forward...
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« Reply #17 on: March 03, 2008, 02:50:32 AM »

A familiar place for me to put CGs is around 15% ahead of the centre of projected wing area of the whole plane (A-2s anyway). This distance we called the static margin. From what you say, I gather that the static margin with canards might be larger? Perhaps they fly with greater longitudinal dihedral (incidence difference between wing and stab -- about 3 1/2 degrees for a Nordic)?

Dan G.
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« Reply #18 on: November 09, 2008, 05:02:08 PM »

Mike, Think your jets are really neat. That F-102 is really kewl. Trick with ducted fans is getting the intake and exhaust openings the proper size, though I am not into things that technical right now. Supposedly, if the openings are proper size and ducting is smooth, you maximise your flow through and thrust. I probably should make smaller models so I can fly next to my house in the open field. Something like you are doing would fit the bill quite nicely.

Caley
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What's stall speed?  Undecided
Mike Taylor
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« Reply #19 on: November 10, 2008, 10:00:50 PM »

Thanks for looking, Caley. Yes, inlet/efflux sizing is a problem on scale models, hence the many 'cheater holes' cut into bodies.
The conventional wisdom is 110% to 120% FSA (fan swept area) and 90% FSA at the exhaust. Even going back to early MiGs and the F-86, there are few that will work superbly without a bit of cheating somewhere. Of course, we make it worse by packing in the biggest fan that will fit.
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crashcaley
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« Reply #20 on: November 10, 2008, 10:20:09 PM »

Mike, the threads over in RCGroups are something to read. Yes, lots of guys over there do ask if a larger fan can be installed. But most just soup up their models by installing a motor that can take two or three more lipoly cells to increase the rpms. I guess those are the guys who have that need for speed. I get excited when a model flys 50mph, let alone 100mph.To each their own. I like medium speed models or slower.  Smiley Have fun with those jets. You may have hooked me on the idea of trying a small one for backyard flying.

Caley
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What's stall speed?  Undecided
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