Search found 4142 matches

by larry cottrill
Mon Apr 23, 2012 5:24 pm
Forum: Off topic forum
Topic: 1960s Stunt U-Control Fix-Up
Replies: 3
Views: 1763

Junior Ready To Roll

I did manage to finish up the Junior Ringmaster this winter, and now I finally have a couple of photos. Haven't been able to fly yet, mostly because of windy weather. While this ship has plenty of power and speed (around 50 MPH in level flight), it is very light and does not hang out on the control ...
by larry cottrill
Fri Jun 03, 2011 4:56 pm
Forum: Valved pulsejet forum
Topic: Technical help required
Replies: 13
Views: 1856

Re: Technical help required

farhad, A couple other things: In my opinion, if your valve and valve plate are properly designed and constructed, there is no need to have the valves slightly open when they are at rest. I know this has been often debated. However, there are lots of valved engines that start and run just fine with ...
by larry cottrill
Wed Jun 01, 2011 4:08 pm
Forum: Valveless pulsejet forum
Topic: Bruno! Larry!
Replies: 4
Views: 946

Re: Bruno! Larry!

Greetings, Paul!

That's a nice-looking one in the photo!

L Cottrill
by larry cottrill
Wed Jun 01, 2011 4:03 pm
Forum: Valved pulsejet forum
Topic: Technical help required
Replies: 13
Views: 1856

Re: Technical help required

farhad_sft, I can't judge your design or construction (I DO agree that the front end "diffuser" shell is necessary, though). Here is an idea that I usually offer to valveless engine builders, but it applies to valved engines too - just in a little different way. It has to do with starting air techni...
by larry cottrill
Mon May 09, 2011 2:41 am
Forum: Valveless pulsejet forum
Topic: Blended bodies
Replies: 50
Views: 6119

Re: Blended bodies

Gee whiz, Batman! I totally misunderstood what you were driving at. Now I get what you mean by "blended". I think I was pretty tired when I saw this and reacted in my customary knee-jerk manner. In my opinion, no matter how much you split up the intake area, you will not have real FWE action in the ...
by larry cottrill
Mon May 09, 2011 2:29 am
Forum: Valveless pulsejet forum
Topic: Glow plug can start pulsejet?
Replies: 5
Views: 1986

Re: Glow plug can start pulsejet?

sedalc, I for one would love to see you make this work. However, it is doubtful. In my early days, I tried glow plugs (small model airplane types) with petrol, alcohols and ethyl ether. I never got a single bang. Not one, not under any conditions. Here's the reason (I think): Glow plugs work well in...
by larry cottrill
Fri May 06, 2011 8:28 pm
Forum: Valveless pulsejet forum
Topic: Blended bodies
Replies: 50
Views: 6119

Re: Blended bodies

Yes, Joe, that should work as long as you keep the impedances (of all the "slices") identical.

A problem I can foresee is the heating of the internal (uncooled) webs. I'd be interested in seeing how your experimental model holds up after some long hard running.

Nice work, as always.

L Cottrill
by larry cottrill
Sun May 01, 2011 2:03 am
Forum: Valveless pulsejet forum
Topic: Big Linear FWE for a Paying Client
Replies: 60
Views: 9797

SUCCESS (Re: Big Linear FWE for a Paying Client)

Got a call yesterday about noon, and the client said they now have it really roaring. They do not feel it is quite as powerful as the original prototype (linear version), but it is apparently plenty good enough to proceed with their experimentation (i.e. proprietary process development). They have b...
by larry cottrill
Thu Apr 14, 2011 1:02 pm
Forum: Valveless pulsejet forum
Topic: Proposed: Linear FWE Rebuild
Replies: 5
Views: 2048

Re: Proposed: Linear FWE Rebuild

Vern - Even at half scale it wouldn't be huge - smaller than the Lady Jane. I am now willing to reveal the IDs and lengths of the linear model. I doubt that you'll be able to get as tight a U-bend as the ones available in Sanitary Tubing, but that doesn't really matter as long as the CL length is ri...
by larry cottrill
Fri Apr 01, 2011 2:47 am
Forum: Valveless pulsejet forum
Topic: Proposed: Linear FWE Rebuild
Replies: 5
Views: 2048

Proposed: Linear FWE Rebuild

Now, here's my plan ... After thoroughly testing the Heater FWE Type I (the linear FWE) the client reported it to be a very powerful air mover. He reported sensible warm air movement at a distance of 45 to 50 ft (13.7 to 15 m) behind the engine. His problem in using the linear engine was the strong ...
by larry cottrill
Wed Mar 30, 2011 4:28 pm
Forum: Off topic forum
Topic: 1960s Stunt U-Control Fix-Up
Replies: 3
Views: 1763

Junior Ringmaster Wing Repairs

Here's how the repair of the Junior Ringmaster was handled. Wingspan of this model is just under 32 inches. As mentioned, EVERY sheet balsa rib was cracked or split in some way. Some of the ribs were knocked completely loose from the hardwood spar. First the ribs were hit with a small amount of wood...
by larry cottrill
Wed Mar 30, 2011 3:44 pm
Forum: Off topic forum
Topic: 1960s Stunt U-Control Fix-Up
Replies: 3
Views: 1763

Mouseclubouse

Peeling off the top fabric of the Super Ringmaster outboard wing, I found: - Mouse tunnels through several wing ribs - An astonishing assortment of seed husks However (and strangely, in my opinion) there was nothing I would describe as nesting material. I guess the critter thought the wing was a nic...
by larry cottrill
Wed Mar 30, 2011 2:23 am
Forum: Off topic forum
Topic: 1960s Stunt U-Control Fix-Up
Replies: 3
Views: 1763

1960s Stunt U-Control Fix-Up

Two rugged and docile stunt U-controllers from the mid 1960s. I built the Super Ringmaster when I was 16 or 17; it is actually my second build of this model. I built the Junior Ringmaster a few years later, when I realized I needed something smaller and cheaper (and easily repaired) for practice fly...
by larry cottrill
Tue Mar 22, 2011 5:00 pm
Forum: Valveless pulsejet forum
Topic: Industrial Heater FWE Type II and Type III
Replies: 7
Views: 1471

Industrial Heater FWE Evolution

Here's a little "almost to scale" sketch I did comparing the three engine models. These are very simple sketches; I have ignored minor variations in the tailpipe length and left out many mounting details. On Models II and III, the intake would normally be on the far side of the chamber, but I show i...
by larry cottrill
Fri Mar 18, 2011 5:32 pm
Forum: Valveless pulsejet forum
Topic: Building an Elektra, need help!!
Replies: 5
Views: 1219

Re: Building an Elektra, need help!!

Can I run the engine on butane? You might get away with this, if you live in a place that is normally nice and warm. Butane has MUCH less vapor pressure than propane at a given temperature. I have always wanted to see somebody get a valveless pulsejet running on butane, but it is going to be diffic...