ChrisAttebery

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Hey Guys,

This is a follow up to Zman's Meerkat thread from a couple weeks back. We both got our inspiration for a memeber of another board. His design is very simple yet very fast. Originally, I was just going to capture his design in CAD, but after talking to Zman and looking at Dave Norman's Seeker plans I got a bit of inspiration to expand the project a bit.

It's basically a Q500 type plane, but scaled down. The fuse is 2.9" tall and 2.375 wide at the peaks. The wing will be a NACA 66-010, 8" cord, 36-42" span. It has about 60% of the frontal area of a Q500 plane. The wing loading will be in the 17-20oz/ft range. Power will be from a Jett SS40. Speeds should be close to 200mph. If not I'll move up to a full Q500 motor.

I'm interested in input on the basic design as well as suggestions on the airfoil. This will not be a racer, just a sport speed toy.


Chris Attebery

ChrisAttebery

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Looks like RCU hammered the sized of the attachment. Anyone got a suggestion for posting the plans without them getting reduced to a useless form? I can put them in PDF, GIF, DXF.

bob27s

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cowl in most of the engine like Roger did on his yellow jacket. but it looks like fun

Scorpion Racing

Chris,

1.) I would suggest using a Jett back plate engine mount first off. It will shorten how far your engine is off the firewall as well as make a very firm mounting. (Less power-loss due to a flexible mount) The dimensions should be 2 1/4" square, with the corners rounded to a 1/4" radius. If you then go to a Q500 Jett or Nelson, it will simply bolt on.

2.) Make the firewall and front of the fuselage as stiff as possible. Vibration will not only cost you power, it can cause enough vibration to break mufflers bolts and other expensive parts!

3.) Bubbless tanks are a must. They are simple, come in a variety of shapes and sizes and will allow you a consistent run so you won't lean out and destroy an engine.

4.) For posting, I think a .JPG gives about the best quality. If you have Adobe Writer, you can export the file as a .JPG.

Good luck with the project, ZMAN seemed to have fun with his!

rmenke

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Some pics, maby.

ChrisAttebery

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Scott,

Thanks for the tip on JPG. That seems to be much better.

The motor I have has the 2" round backplate. If I upgrade to the Q500 I'll get the square plate. The tank in the drawing is a Tetra 6 oz bubbleless. I plan on stiffening the nose with tristock in the corners and carbon or glass behind the firewall.

Thanks!


Chris

ChrisAttebery

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Hey Roger,

Could you post a picture of the cowl on your Yellow Jacket? I found one picture you posted, but it's from the right rear side.

Thanks,


Chris

HighPlains

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I'm glad to see that the MeerKat has sparked some interest in simple cheap speed designs. Your model size is around what I have been thinking of building too (that, and also because I've got cores for it already).

I don't think the Jett 40SS has the stones to reach 200, but if you can get it propped right it won't be too far off. A full blown quickie engine might not be able to achieve it either, mostly due to problems finding a prop that works. Both types of engines only turn in the 20 K range, and would require a very over-square prop with poor efficiency.

I would look to a QM engine instead, as they can turn the rpm needed and props are available that work. Another high rpm type of engines would be old Formula One engines.

Anyway, I'm looking forward to seeing your project develop.

ChrisAttebery

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Thanks for the input Bob. I've been reading a bunch of your old posts lately. I was very tempted to try out some of your fuse shape ideas, but decided to keep it simple for the first try. You're totally right on the QM motors. I think that would be the way to go.


Chris

combatpigg

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Chris, it looks great and thanks for sharing your design. Hope you crack 200 with it!

HighPlains

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Chris,

The fuselage design is overlooked as a major source of drag, especially at the wing/fuselage junction, so I have posted on it quite often. On the quickies I flew over the years, there were many slight changes from plane to plane as new concepts were incorporated.

Anyway, you have already accomplished the most difficult part of design - a decent name for the airplane. I have to admit that I had no idea what the hell a Meerkat was. Then one day I was napping in front of the TV, and I must have rolled over on the remote and ended up on the Discovery channel. And there was the answer - Meerkat Manor.

I also noticed somewhere that Daven has one of these little ships under construction, but I fear it will be underpowered with a Nelson .15

Zman39

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Looks good Chris. I sent you a pm on the other questions you had. Look forward to the project!

Z

Zman39

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I thought Meerkat was neat[&o]lol..........Several pylon racers around here are flying Scorpions which were designed by Scott "Scorpian Racing". This plane has proven to be a winner in pylon races. Anyway, A Meerkat is an animal in Australia that feeds on Scorpions as part of its diet. I think it is only animal capable of it without keeling over dead. Anyway, being that the guys that are racing scorpions are also my good flying buddies, meerkat was an ideal name to dig at them a little and neat thing is these same guys were the ones who helped me achieve the speeds. But in all fairness, the Meerkat is a "touch" smaller so we arent comparing apples to apples.

bob27s

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if you design around the round backplate, no problem using that same backplate on the 428 engine and the 422 qm engine later on if you want to. They are all interchangeable.

ChrisAttebery

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Like Zman, my name is a dig at the only other Q500 type planes flying at my field, the Viper. At that I think they are only using the 424 setup. Who eats vipers for lunch, the Mongoose of course.

rmenke

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CA:

Sorry, tried to send you come pics over two days, computer or mind is not cooperating. Gonna send you intended text and fllow up asap.

Want to give you benefit of several years in R & D with wing spans and improving the standard Q-500 moments to something more. Weight of the airframe and power natrally modifys things a little, but we are talking about a fast and fun airframe. To me, thats one that will turn left without skidding, still be able to land at the typical Q-500 moderate speed and sport fly to some degree. My first bird dubbed the Yellow Jacket started life with typical Q-500 moments with the nose streemlined, split elevators for a tail wheel, low Viper or Dodger Wing. Original power Jett 35, wing span 48" after repairing a free wing. Overall it was fairly fast, but needed more. Cut wing down to 44", 42", 40" and 38". Until I hit the 38" mark, everything was great, each cut brought a little more speed. The 38" wing skiddind badly in a sharp turn, normal for my naormal racing style, genera overall flying characterists not acceptable, total dry weight 4.64 lbs which includes lots of repair glue. When back to 40" turns solid and sharp, still good landing character. Took the gang over 4 years to beat this little guy over 50% of the races, time to R & D. Still serves as a backup to this date.

YJ II, version I started life with a high wing design much ala Q-500 except Jett 60 LX power, 40" span, 4.15 pounds dry. Scary fast, solid, landed well. A bad switch made it go in WFO. The speed as such was much more than needed, so when I built version II I increased fuse width and depth to accommodate a 13 oz tank. Only wing available at the time was a composit type 52" X 10" cord. Left it 52" for the maden. Can be cut down if needed. Maden flight uneventfull, noted speed still high but currently manageable. New dimensions make the current bird fun to fly. Start on a stand, needle as needed, sit down, idle out and take off like any other sport aircraft. Be back.

HighPlains

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Pigs do fly!

MJD

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If you can approach 200 with a 10" chord, you are getting into the sweet spot of Dr. Hepperle's new speed airfoils - Rn of 1.55-1.60 x 10^6 - and they may be of interest. These are the MH-50 through 54 series. You'd need to consult the data to see which one fits the expected speed regime best, some are good at the 175mph mark and up, some biased alittle higher. I can't tell what chord you have selected there, that of course affects Rn.

I've done some figgerin' with these airfoils for a speed design, lemme know if yer interested and I can offer anything, at the very least an airfoil plot if you don't have it available.

MJD

ChrisAttebery

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Roger,

I sent you an email.

I'm short on time tonight, so I'll get back to this tomorrow.


Chris

ChrisAttebery

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MJD,

The cord will be 8". I think at this point I'll stick to the 66-010. The 66 series is what most of the Q500s use these days. I don't want to push it on my first design. I've never designed a plane in my life. I 'd really like to start with a known quantity and work from there. I've already changed the wing thickness, cord, nose length, tail moment, vert stab shape, and the cross section of the tail boom. Hopefully I haven't made any errors there.

Thanks,


Chris

ChrisAttebery

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Roger,

It looks like the sweet spot for the Q500 wings is around 24oz/ft. At 3 lbs and 42" I'm at around 20.6oz/ft. With at 36" wing I would be at 24oz/ft. The big wildcard in my mind is the fact that the wing will be ~33% thinner so the cubic loading will be higher. I guess I can start at 48" and just cut it down a bit at a time.

I flew at Jepe Pyranha EDF for about a year. It weighed 37oz, had a 8% wing section and ~26oz/ft loading. It flew at around 135mph, was a kick to fly and din't have any bad habits. I'm hoping for similar flight characteristics, just a bit faster.



Chris

bob27s

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just build it time to shoot the engineers and begin construction [&:]

z06kal

From my experiance wing loading will not affect straight line performance much. The difference in drag between the tiny angle of attack change between flying a 24 oz/sqft wing or 35 oz/sqft wing at 200mph is pretty much insignificant and thus you will not see any easily measurable speed difference in level flight between this plane at 3lbs or at 5 pounds. If it's heavier it will much harder harder to land and not accelerate as fast or come out of turns as fast but if we are talking just level flight speeds it is not a factor when going for just all out speed. THe heavier plane will also have much better speed out of a dive.

Personally I would make it electric and make it as aerodynamic as possible. Your flight time wont' be that different than a Nelson motor running on 6oz of fuel.

ChrisAttebery

My Feedback: (15)

Bob,

You're right. I'm not going to have any major inovations to contribute to aerodynamics here. I'll get teh balsa this week and get going.

Kal,

I had a Sunracer at 400W, a couple EDFs up to 900W, but the cost of airframes, batteries, and electronics are killing me. Balsa and foam are cheap. I'm a nitro junkie anyway.

Maybe someday I'll get that 1kW Jibe or Nemesis, but not right now.



Chris

rmenke

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HP;

Pig, pig, pig, pig. Ohhhhhhhhhhhhhhh that hirts. Truth be told, remember this little guy was in the club racing wars for more than 4 years, and is still flying while many others are reduced to scrap, some by chance, some intentional. Never said I was a nice guy to race against. Landing gear, both in wing epoxied back many times after getting some tail. Fuse repaired and glassed several times from side impact, loose wing/motor mounts etc. But, still flys and lands well. Maby should build a improved version just to get the weight off? Bro 119