Looking for Pulse Jet Help (Dynajet Redhead?)
 

A gentleman stopped by the flying field this afternoon looking for some help with a pulse jet engine. He said he had seen one run when he was a kid and recently he ran across one and purchased it. He knew nothing about the engine, but from doing a bit of web surfing it looks like his engine is a Dynajet redhead.

Does anyone know where I can get some instructions on how to run this beast? Any other information on this engine would also be welcomed. Anyone know the value? I did not know where to post this, but a search of RCU showed that most of the pulse jet threads were in this forum, so I thought I would stick with the crowd.

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Get in touch with Bruce Tharpe. He has had lots of success with pulse jets.

www.btemodels.com

Regards

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

And I'll alert PulseJet Harry to your dilema!!! He IS a certified super hero. It's just that you hear more about Batman and Spiderman.

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Thanks for the link Tommy.

I have read about Harry's exploits. I wonder if he would be willing to travel to Alabama as a technical adviser?

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

He is already here and is about 20 feet down the hall. We were both relocated temporarily to Marshal Space Flight Center by Lockheed Martin from MAF, due to hurricane Katrina. We are in the old Integraph buildings out by Madison off of Wall-Triana, if you know where that is.

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

I know where Marshall is but not the specific location. My in-laws live in Decatur, so I travel up to your area a good bit. Interested in some hands on tutoring? :D

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

You need fuel, air, and spark. Coleman fuel will work great, air can come from a compressed air tank or bicycle pump. Spark is the tricky part, you need a "buzz box" with a Model T coil and battery to provide a spark while starting. Once running, you don't need the spark anymore (but you will want earplugs!).

I can send him a copy of the original Dynajet instructions if he wants...

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

depfife

You can go direct to the manufacturer http://www.dynafog.com/other/index.htm
or this site has the best info on pulsejets http://www.pulse-jets.com/
Adam

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Try the control line speed boys as well. In the UK there are a small group using pulse jets in CL speed models.

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

I have endeavored to have PulseJet Harry PM you. Has he? He is awfully busy as it appears his time here in Huntsville is just about over (he plans to return to New Orleans on Thursday, but that could change). I will bug him again today.

Bruce is by far the P-Jet expert here, but I have some run time on Harry's engine. One thing I found was that the engine appeared to be VERY critical of fuel head pressure: the height of the fuel tank made all of the difference in the world when running with no fuel regulator. Once Harry bought that little fuel pressure regulator and used the surgical tubing bladder to provide pressure, all went well. Bruce, can you tell everyone where they can get that regulator?

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Hey Wocket, thanks for the vote of confidence :) but I'm trying to keep it simple here. The bladder tank/Cline regulator setup is great if you plan to fly a Dynajet and do aerobatics. Sounds like depfife and his friend just want to hear it run, which is a thrill in itself. The CL speed guys will spend all day telling you how to hop it up and mix special fuels.

The original Dynajet instructions worked well for thousands of teenage boys in the 40s and 50s and 60s and 70s, and are still valid today. They are something like 12 - 15 pages, so its easier for me to just stick it in the mail than post here. Wocketman is right about the fuel tank height. Use a small tank, 6 oz. max, and position the top of the tank even with the metering jet (fuel inlet) on the Dyna-Jet.

Depfife, if you want the instructions, just send me a PM, or visit my website and find my email, or call me at 541-582-1708 (Oregon). If anybody wants info on the bladder tank setup for RC models, contact me - happy to help.

Bruce

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Here's a simple schematic of the buzz box you need to provide spark:

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Thanks for the help guys. Bruce, I sent you a PM with my mailing address. I'll keep you posted on the progress. If we can get the thing to run we may progress on to mounting it on something. [X(]

Woketman, nothing from Harry yet. Getting my hands on the original instructions will make me feel much better.

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

The allusive Pulsejet Harry has checked in! These engines have received a lot of bad press, but they really are easy to run once you know what you are doing. As Wocketman said, the head pressure is important. Make sure the read valve is clocked properly. I had a read valve come loose and rotate out of position. Flames shot out both ends of the engine. Looks cool, but adversely affects the performance! If you don't have a sparker box, I've read about people tapping off their engine ignition system. You can disconnect one of your spark plug leads, hook jumper cables to it, and run it to your engine. This might not work too well with newer cars, because the engine diagnostic system will detect un-burnt fuel in the exhaust and might try to compensate and make the engine run rough. If you have any questions, you can contact me a [email protected].

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

He speaks, HE SPEAKS!!! It only took a week of me bit*hing at him to get old PJHarry to reply (and he's just a few yards down the hall)!

Now, we gotta get him to post the video of one of his early attempts to get a PJ running (hint: it involved automotive brake cleaner and the excitedly uttered phrase "IT'S RUNNING, IT'S RUNNING!!!")

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

The owner of the Redhead stopped by the field yesterday and I caught him up on the information that has been provided. He has a Model T coil, so we will use the schematic Bruce provided.

Thanks for checking in Harry. I've seen your name mentioned so often whenever DynaJet is mentioned on RCU it would not seem right to proceed without you.

Once I get the instructions and give them a read, I may have more questions. Right now I am in wait mode.

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Bruce/Harry.....

I've Charley Chambers old DJ (bought some years ago from FT)....now have the alcohol fuel nozzle, runs terrific on test stand w/ tank at the proper level. I've been thinking of putting it in an RC V-1 Buzz Bomb...would be very scale but has obvious need of a pressure regulator system and pressurized tank, I'm sure (CL of alky tank would be about 4-5" below the fuel nozzle).

Bruce, I'd be most appreciative if you would mail me the 10-12 page DJ instructions and any specifics re the regulator/tank set-up I'd need, esp pressuring the tank.

Harry...your comments would be most welcome!

Ray Davis
3 Green Harbor Road
East Falmouth, MA 02536

[email protected]

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Consider it done, Ray. Instructions are already on their way to you, Depfife. Glad to hear he already has the coil; that's the only "big ticket" item he'll need for the buzz box.

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

The pressurized fuel system that I use comes from Bruce and utilizes a Cline fuel regulator. I used wide diameter surgical tubing from McMaster Carr for a fuel bladder. You can use 45 cal shells for the end caps of the fuel bladder, but I machined mine out of aluminum. I would highly recommend the cline fuel regulator, especially if you plan on trying to fly the engine.

Do you plan on launching off a runway or catapult?

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Ray,

I've looked at doing the V-1, but I've always seen a CG problem. The DJ weighs in at about a pound. When you build a delta wing model, the one-pound engine at the rear is manageable. But with the V-1 wing configuration, you have to use about a 1.5 pounds of ballast in the nose to give an adequate CG. You can move the engine forward, but then it kind of stops looking like a V-1.

Harry

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Harry/Bruce....most appreciative of the help/advice!

I'd build in one (or tandem) main wheels in the fuse to stick down some minimal amount, same at the wing tips w/ small dia wheels/skids. Both should be practically unnoticable. And....maybe a scale launch/catapault. I'd have all TO and landing options that way. Still thinking about it...but should be spectacular...get it up high, kill the engine, drop it straight down.... In the thinking stage, possibly time for it this winter. Been out to Chino, got fascinated w/ the one on display out there. The full scale is crude, so easy to do in a model; there are plans somewhere I've seen. Scale it to make the (cleverly...;)) enclosed DJ look right. Tx

Ray

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Ray,

I would recommend the runway, only because my DJ has the scars from alternate launch methods. When the engine is running (i.e. HOT) it is easy to damage. If ruptured the engine a few time during "not so successful" launches. However, the engine is easy to repair if you know a welder.

Harry

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Bruce had one on a airplane at a fly in in Madras Or. several years ago. I can't remember for sure but I think it was in an airplane of somewhat similar design to his R-54. He Started it up - no throttle of course - Then flew it around for about 10 minuets. Extremely fast!!!! And loud!! It ran out of fuel, he glided it around for a landing and had to walk about three steps to retrieve the airplane. Very impressive!!
Bruce, how about posting some pictures of it ?
Galen

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Galen, it just SEEMED like ten minutes. Flight time is actually closer to four...

Pretty sure you saw my Double Whammy, which is a twin Dyna-Jet sport model. You can read more about it here:

http://www.btemodels.com/doublewhammy.html

RE: Looking for Pulse Jet Help (Dynajet Redhead?)
 

Bruce, love the heat shield on that double whammy. Woketman can attest to inadequate heat shielding. My test stand erupted in to flames a couple of years back. What a riot!