combatpigg

My Feedback: (3)

The flight report with the increased power is well.......not much to talk about. I was by myself, so there wasn't any clocking, but I didn't see much improvement. The combination doesn't massively unload, it runs pretty much in the air the way I set it on the ground, the unloading is just average. The K&B really is a nice engine and loves the 50% nitro, it landed cool each time today and only used 1 plug in 6 or 7 flights. I tried a 8x8 on it and it flew about the same, no big unloading. Obviously, Der Stuermann, SloMo, Highplains and others know about what they are saying when it comes to deltas. this one is 31 inches in span, and about 24 inches long. I suppose it could be shrunk down a bit and still be flyable and within reason to land. Now I would REALLY like to see a delta in this size range do even just 180 mph. Bottom line, to enjoy a .40 sized delta for what it is, and have a hassle free set up, I would forget about the cowling, bladders, oversized venturis, etc., and just slap on a JETT or similar engine that runs good off of suction and just have a good time.

HighPlains

My Feedback: (1)

A few things to consider.

A normal F1 motor had the exhaust timing at around 168 degrees, so it had a bit more torque to turn the higher pitch props. A very clean F1 could run up to an 8" pitch, but most ran 7 1/2 or less because the needle range got very critical. There was a thread some months back about a F1 making passes at and above 200 mph. You should be able to add 10 to 15% to that with a well designed conventional airplane that is smaller and cleaner than an F1. You were on the right track with your old thread on building a speed plane.

It also had open exhaust with a 3 3/4" mini-pipe (straight piece of conduit, with a O-ring groove cut inside). Unlike a tuned pipe engine, one with open exhaust is free to turn up to what ever rpm that the drag of the airplane allows. So where an engine would be set to run 21,000 to 22,500 (K&B to ST), in the air while on the course it would unload another 5K. Put the nose of the airplane down and it will continue to unload even more.

The tuned pipe engine will be limited in rpm by the pipe - a very effective governor. Your option with the pipe is not to be on the pipe until you dive into it.

deckerv

My Feedback: (21)

HS-5625MG is what I'm using on my whiplash. It's 110oz, but they seem to be holding up very well for me.

combatpigg

My Feedback: (3)

I'll have to give the open exhaust a try then. The other point you make would mean starting over with a full length header and tune the system through a series of inflight dive tests, VS tuning the system on the ground with a tach only. This is where I feel that working with a bladder is a plus, inflight G forces have less effect on fuel delivery. I don't have much of a prop selection to work with here, that is another item to address, I figured that the 7.7x8.6 was going to be the ticket, enough pitch to create some speed from the given rpm, and enough thrust to fly the plane. This plane has a surplus of thrust, it launches vertical, I'll bet the prop could be cut down to under 7 inches and still fly the plane. I think any serious thrashing while the K&B is bolted to this delta air frame is a waste of time, it's time to call this one good and move back into the speed plane idea with a Nelson .40. I gotta say that the K&B is a great engine from what I've seen here, it lands cool to the touch, is smooth running and easy to handle with a bladder and Nelson needle.

MyWay

Try an apc 8x9 and then 8x10. The launch will be worse but the speed will be better when it unloads in the air.

combatpigg

My Feedback: (3)

I think some progress was made today. first, I ditched the pipe and the K&B responded very well, the unloading was much better, but the .40 doesn't have the cajones to maintain the rpm increase for what looks like the entire 660 foot timing zone, it drops off after about 300 or 400 feet, but I'm just gauging this by eye for now. I think 8 inches is too much diameter for this engine, the workinest prop off the shelf has been the 7.2x8.6 APC, so what I did was cut one down to 6.75" and reshaped the blades. I think I am working in the right direction, the speed out of the dives seems better and the speed lasts longer on the level. I also took the pipe off this planes' bigger brother, a 36" span delta with a Webra .50, and I run this one with a 8x9. It likes the open header, too.

Here's a family photo.........

freakingfast

My Feedback: (3)

Hummm,he must like deltas

combatpigg

My Feedback: (3)

We set up a 1/16th mile timing zone and got some clockings today. The clockings were within a hundreth of a second of each other per flight.

K&B .40 31" delta 6.75x8.6 APC open header...................................177 mph
K&B .40 31" delta 7.2x8.6 APC open header...................................163 mph
K&B .40 31" delta 7.2x8.6 APC piped............................................. 155 mph

WEBRA .50 36" delta 8x9 APC piped............................................. ...155 mph
WEBRA .50 36" delta 9x8 APC piped............................................. ...153 mph

combatpigg

My Feedback: (3)

It is interesting to see the WEBRA loafing along but turning in a respectable speed and to see the $65 K&B engine doing almost 180 mph with a first attempt cut down APC prop. There is not much left to do except lots of engine work and prop work that might gain another 5% of speed, I would rather call it a day and get back to work on a purpose built speed plane.