rcguy59

My Feedback: (8)

I hate it when that happens.

combatpigg

My Feedback: (3)

I love that 70% DD with the K&B .21..! Looks perfect.

combatpigg

My Feedback: (3)

No doubt. Is that the way the Rapier looks stock or did you enhance it...?
If I owned a delta that size, I'd stick a BFE on it and maybe some prop saving skids and just run it on methanol for some great looking fun.

Mustang Fever

My Feedback: (2)

I'd sort of forgotten about the Enforcer. I dismissed it as a project because I don't want anything to do with pusher glow engines.

But.......I'll bet this bird would make a wicked electric conversion. By using a Rimfire 32 on 5S, the weight comes out the same as with a 46 glow, 8 oz of gas, and a 2000 NiMh Rx pack. It would honk.

I'm thinking electric retractable gear, and do something about that canopy to make it look less nauseating.

freakingfast

My Feedback: (3)

Ahhhh. The red, white & blue with American made engines! Makes me feel...patriotic

Crazy4Flight

My Feedback: (540)

Does this qualify?????

I found this SR-71 on my to do pile.

Bought it a few years ago it is built from plans. "45 size"

Hand launch pusher prop... but it does have provisions for fixed gear.

Its built light so can be converted it to electric.. toss hit the throttle and no prop strikes to the hand.

Crazy4Flight

My Feedback: (540)

I spent months looking for a Carb for the K&B .21 it had a venturi.

There was no way I was going to fly it flat out on a maiden flight.

freakingfast

My Feedback: (3)

Couldn't agree more with Speedy's statements, especially if your running a monster motor (D.F., Jett 56 or Q40), and big throws. With those conditions you may want to add some 5 cell high mah AA or even better 5 cell 2/3 A's for high current loads under high speed high control surface deflection or risk the receiver going brain dead. Control surfaces on deltas are huge compared to other types planes, it's why they maneuver so well, or scrub off speed on anything more than a hard 90 degree turn.

If running a mouse motor OS 32, Webra 36 for instance, you may not need as much servo and battery.

retnavycdr

My Feedback: (190)

Still have this BTE delta with OS Max .91. Good speed and lands sloooow.

daven

My Feedback: (1)

My whiplash and Jett .50, unfortunately, she was short lived. Pilot error..

iron eagel

Another important aspect is setting up your servos for the best mechanical advantage, this in itself makes a world of difference in the airplanes response and the force required to move the surface. Today far to many rely on setup functions that can be done with the radio and do not set up there control linkage to set up their throws like it was done in the old days prior to computer radios. For most applications this is not an issue but with something that higher speed it is an important factor due to the forces on the control surfaces when the plane is really moving fast. Combatpigg and a few others have often made mention of setting up their planes in this manner, if you haven't tried it you should, it make a world of difference on the servo loads.

iron eagel

When Mike Connor first designed the SD I got one of the first kits he produced before passing the kit production on to someone else. It's still in the box waiting to be built, I can wait to get it together CP and a few other have shown if set up right it can be a very quick bird.

erbroens

Have seen this thread on the main page. A excellent choice of double delta flying was Hanno Prettner´s (google it if you never heard of him before) super simple design. This guy in my opinion was the best r/c pilot ever.

Plans are not needed at all, and it can be built in many ways and in any size, with or without landing gear, glow, electric, EDF , ICDF or even with a turbine if you fiberglass it.

http://www.rcuniverse.com/forum/m_39...tm.htm#3965726

http://www.rcgroups.com/forums/showthread.php?t=434265

have fun!

Speedy-Gonzales

My Feedback: (202)

The "Rapier" and "Screamin Demon" were both highly modified with basswood spars sandwiched with .014" carbon
strip on top and bottom. Fully sheeted airframe so airfoil woul hold true form. Open structured wings will actually bulge toward the rear of the wing at high speed due to the ever existent vacuum created by the wing traveling through the air.

This anomaly was actually the demise of many Diamond Dusts and the reason they would shed their covering. The other advantage of a fully sheeted wing is that IF you shed the covering.....you still have a wing underneath!

The nose was narrowed to match the 1.5" diameter nelson counter-balanced spinner and a 1/4" thick aluminum
plate was incorporated into the nose for the engine mount. I NEVER rely on 1/4" plywood plate for a motor mount
on a Nelson or other engines of same class. You need the rigidity and you do not want a material ( plywood )
that will compress in any way.

This is turning out to be a great forum!

SPEEDY

Max_Power

Crazy4Flight, you had referred to a thread with some RPM#s on the K&B .21 somewhere. I've searched , but for the life of me can't find anything. Can you point me to any good info on this engine? I picked a brand new one up last year for a song and dance and am trying to figure out what to expect from it and what to mount it to. I am also looking for a source of bearings for a K&B 6.5 FIRE engine for less than the $80 BOCA wants if anyone has any advice. Thanks in advance, Todd

iron eagel

I am will be doing some modifications to the SD as well.
I am going to fully sheath it as you did with yours, I pretty sure Combatpigg did so as well with his for the reason you mentioned.
Where I am going electric I am going to have to do some major rework of the spar system to allow for the battery to sit down in the fuselage .
I am still going back and forth about building it with a vertical fin or wingletts.
One additional thing I am going to do as well is to add some .002 carbon fiber rods diagonally on the elevons as I did with my PQ stingray. Adding the carbon fiber really stiffened up the elevons quite a bit because one of my concerns with high speed designs are the elevons not being stiff enough and causing flutter.

Mustang Fever

My Feedback: (2)

These were deltas, too. I watched them in the pattern a lot during my ANG days, and was always astounded by how high they could get the nose up on approach and still stay airborne. Judging by the noise, they were close to full military power on those J-79s so the drag at that AOA wouldn't pull them out of the sky.

Crazy4Flight

My Feedback: (540)

try www.mecoa.com they bought K&B after they closed.

or

http://www.ebay.com/itm/K-B-6-5-QUIC...item4cf6ac41fa

Crazy4Flight

My Feedback: (540)

BTW MECOA has K&B GLOW PLUGS 1L and HP
and 20% off sale on glow plug on 12 or more

lfinney

My Feedback: (44)

the k&b .21 will turn a 7x6 master airscrew 21.5 on a macs pipe or wizard minipipe stock, if you use the .40 size perry card which is a drop in, the 23-24k on 15 percent nitro , very good throttle response with either carb with pipe. easy on plugs and bearings as well. so in the air nearer 26k rpm as it really unloads.

weazel1

hey all what would be a good prop and pipe to start with on a kb 45 d/f motor on a q500 ship i got three of these so i want to try it out on one

Captain Terrific

My Feedback: (2)

What happened to Mikes RC and the sreamin demon? Website is up and taking orders. Any thoughts?

Dave

Speedy-Gonzales

My Feedback: (202)

I run vintage Rev-up wood props on my K/B 7.5cc DF's. 8.75 x 6.5 and 8.75 x 7. Make darned sure you run a castor based lube. These engines use the old metallurgy and need the lube or you will score a cylinder. Run nothing less than 20% lube. You can run synthetic/castor blend but no straight synthetic or you will smoke it. My fuel of choice is POWERMASTER 10/22 which is 10% nitro and 22% lube. Half of that 22% lube content is synthetic and half is pure racing castor. So you are getting 11% synthetic and 11% pure castor.

For a comparrison let's use WILDCAT 10% Premium Extra. It is 10% nitro and 18% lube. Of that 18% lube you are getting 90% synthetic and about 10% castor ( or Klotz Super Techniplate ). If you do your math 10% of 18% ( total lube content )and you are only getting 1.8% castor ( 2.3 ozs. ) in a gallon of fuel. That ain't enough...plain and simple.

Do what Nelson recommends for their engines. Add 6 ounces of castor to your gallon of fuel if you are running standard 18% lube. I also recommend the McCoy MC-9 or K/B HP glowplug. Run your engine rich and be patient with the run-in process or again...you will burn it up. Many guys get in a big hurry to go out with these older engines and go for a balls-out full throttle flight on the first flight. It don't work that way with the K/B's.

K/B got a bad rap because of guys not taking the time for a proper run-in period. Check your head bolts after a few runs. I use an adjustable inch-ounce torque screwdriver on all my racing engines. I bought one calibrated for aerospace applications and it is the most important tool in my engine cabinet. I use it in every bolt on the engine.

Many of the car guys will argue about lube and lube content but not many guys are running their cars at full WOT throttle for extended periods of time. They are running short bursts and big heat sink heads. You can not compare car/buggy engines to aircraft racing engines. They are not opertated in the same manner. If you ran a car/buggy engine at WOT for 3 minutes you would have to go to the next town to find your R/C car.

Boat guys have the advantage of using water jackets and the ability to cool a boat engine with water circulating around the head and combustion chamber allows for super high RPM's and lots of nitro.

As R/C high performance aircraft engine operators we have but only 2 ways to keep an engine running cool and lubricated for extended periods. Good quality lubrication and air. Screw up on either one and you will pay the price with a torched piston/sleeve assembly. A "sport engine" does not require this much attention but once you enter the "Speed Freak's" world you will learn in a big hurry what works and what doesn't.

You will also find the concept of just adding more nitro will make your engine run harder. This is a big misconception and FAI racing engines have debunked this train of thought since they will outrun any fire breating nitro monster on ZERO nitro fuel. It is the porting and crank timing that makes a racing engine rev and develop the power that it does.

I live by this rule:
10-15% nitro is plenty in any engine. Nitro is heat. Heat is bad!!

It is not my intention to start another firestorm over fuel and lube. These are just my own personal guidelines....and they work!

weazel1

ok thanks man i know the lube concept due to my older os 90 df motor and added the castrol to that so thanks

freakingfast

My Feedback: (3)

About 13 years ago, some Diamond Dusts kits were shipped with under size aileron stock. They all fluttered, even with small engines! I cant stress the importance of having the laminar airflow coming off the wing being lined up for contact with the control surface. (at least in the centered position).

If you are skinning the wings, be sure that the fat part of elevons are at least as thick as the TE of the wing. I don't care how stiff they are, if they are too thin, you'll get the buzz of death.