hello dave.... well here's the deal.... went and got a new manifold gasket (other one was really torn) and ran the engine.... it would maintain a steady run (for once) but wasn't running on the pipe.. i wanted to see if maybe there wasnt enough pressure comming from the tunnel so i cupped my hands around the exaust and pretende i was a adjustible tail cone... it seemed the more i brought the rear section down the more rev's i was geting but i noticed the air was backing up and basically unloading the fan... (causing the higher rpm...) so my question is this... does this indicate that its not getting enough air in? out? or should i check the pipe length? (engines pipe) i have the video of the OK models DJ-1 and DJ-3 and they are haulin some serious butt... the DJ-1 is basically a all balsa zaggi with a nose pod for fuel/ radio gear... and the plane leaps of the ground in about 3 feet... and its engine is exposed and no ducting...

oh if your asking the weight... its in the ball park of 2.5- 3 lbs.... my scales are for heavy stuff so it goes from 0- 5 - 10+ lbs... so it kept reading about 2.5

Matt, I doubt more air is needed, as the chin inlet is large, and the aux intakes on my A7 always 'sucked' lots more in! I considered playing with the exhaust duct size but decided against it.
My engine came pre- setup so I cannot advise about pipe length. I would have thought it should 'be on the pipe' as per the length it is. Still using 30% and a #8 plug?

What distance do you have between the pipe and the header? this should be minimal

Dave

Matt,

If your A7 weighs only 2.5 - 3lbs then you'll have one of the best flying HB A7's around. Mine was in the region of 5lbs, as have many others. Are you using Lipos?

no lipos... im husing the hitec hs-55 (lil blue buggers) for ailerons, and throttle, a draggan fly "9.gram" (canadian knock off of hs-55) for the elevator and a futaba s-133 micro sevo (almost liek the hs-81's) total weight now of gear.. 1.7 ish oz... servos.... 1 1.5 oz receiver (futaba r-127df me thinks) and a hand built 360 mAH NiMh... cells look like maybe AAA.. but only 2/3 length... weighs like no more than a oz....

oh while i was taxing the beast... it still suffers (sucks) and does not seem to build up enough speed to do much.... like.. get off the ground... maybe the wheels are too small?

Yes! You could increase the main wheels' size, and increase the nose wheel size twice as much as you will gain a + AOA.
Also, if you haven't already, dial in some flaperon mixing. Set them to 10-15 degrees for takeoff.

Just been back over the thread (from the distant past) and wised I'd stored the A7 airframe! It really would have gone like the clappers on mw44. Finding room for a litre of kero would have been the most problematic. Also, that tailplane/fin brace wouldn't have liked the heat from the 44

see i thought about it.. if i can get it to run ill put bigger wheels on it... and hopefully be able to test fly it for this weekends jet ralley.... speaking of the tail posts.. i must of done something wrong... as when i was checking to see if i could loosen the pipe without having to pull it ouf of the plane i notice they had popped loose... i going to fix them with Cya. and call it a day... i have to seriously cut down rudder throw as my stearing is crazy on the ground.. my r/c cars are not that sensitive... i noticed that you say i wished i kept it.... did you ever get the conversion working? last i heard was the spinner problems.... and you did something to the engine....

No, it didnt work out, unfortunately. You on grass or Tarmac? Did I ever upload my maiden flight vid? I'll have to find it and put it up (i'll edit the top gun theme out for you lot though

lol i have one that was from here i beleive... you never bungied it did you?

ohh... tarmac... according to an article... its 350mm from back of engine to tip of pipe...

The instructions that come with the engine/fan if you buy it seperately state the pipe length is 340mm from the rear of the head to the back side of the pipe (does not include stinger).

I had two of these, logged some 500 flights on them, nice airplane.
Futaba...you NEED 30% or more fuel. Need.
And...you need to tune the pipe properly. 350mm is just a starting point, you need to tune it for local conditions and fuel.
Awful lot of people got pretty mediocre performance by not tuning the pipe.
Do these things, or keep crashing the airplane.
Doubt if interference from a metal clevis had anything to do with anything, more likely the plane simply tip stalled.
Weight is not the issue, mine weighed some 66 ounces and took off fine.
Also, make sure you do not have the main gear installed backwards, it will put the mains too far backwards.

I bungied mine, nice improvement in performance without the gear, but bungees are a hassle.

I tried an adjustable tailcone on the A-7, the designed has already arrived at the optimium balance between static thrust and top speed.
Intake area is adequate, too.
You aren't on the pipe!

well............................ ok.. i had a fairly decent b-day.... and i accually got the bird going.... here is a list of my problems....

first off i really impressed the jet guys with my ducted fan car.. only to realize that i wasnt reaching full throttle mecahnically.... FIXED

after adjusting the thrott... went to start it to make sure its going to run and to adjust the pipe... only to pop the starter line.... but the engine ran... ( unfortuantly due to mechanical issues it was rigged to start/idle at half throttle..)

out came the fan and waited a hour and a half for my dad to bring me the replacement i had... starter on now... pulls...runs awsume.... (previous owner said that it sounded better than when he owned it)

refuled/ started taxied out... wind change... taxi to other end... repeat... then flip (because of wind)

restart, taxi.... change direction... full throttle... release the beast... good roll... easy up... easy... cleard the runway.. turn east (toward electric fence) wind shifts again (tail wind now) engine dies... nose over.... waaaam! receiver opens its eyes to daylight and dirt...

id admit.. if for what ever reason the engine didnt quit it would of flown just fine... id say it took maybe 3/4 of our 600' asphalt strip and was at a great climb angle.... it was the sudden tail wind and flame out that killed me... i had a grin on my face all through the breif fight... it responded well..... now that i got my feet wet in ducted fans... im ready to work up to the bigger boys... but first i got a few ideas for that fan.. i see some improvements that are being made.. and it craves to go in a mini................................ < secret prodject!! sorry... however... i wish that i had enough for one of those mini turbines... some solid sheet tail feathers.. and about 4 hrs of repair to the nose and the a-7 would be splended.... im not giving up on this airframe..

but another problem is that i painted the nose again after the last crash... maybe that is my bad luck... spent about 2 hrs airbrushing exaust & other lil details...too... but all in all what little i did get from its flight... i enjoyed it... but for now... my mini.............................. is what is going to do the trick.... stay tuned.....

has anyone else built a new airframe for the toki fan????

hmmmmmm, sorry to hear you had limited success again. Don't give up.

well i found a plan for a plane called the hot spot.. for the 7.5/ turbax unit... and a plan for the joe-cat.. (for toki) and hum.. combibe the two.. ad a lil this and that... a mini bob-cat looking plane.. hum.. or a balsa bandit mini... or a f-15... gurr choices choices choices...

EJF sells a mini bobcat that would probably do alright for toki. Be aware of this, though, you do not want the engine too far back.
C/G, you know.
Also look at the Pilot DJ-1 kit.
And Toki has a new bird coming out called the Ducty.

I have the wood version of the EJF Bobbycat (still in kit form) and it looks really sweet! Yes, balance could definately be an issue with the heavier engine so far back. But, the model is supposed to handle pretty high wing loadings. When I bought the kit I asked about flying weights and was told that up to 6 lbs. would not be a problem. I can't see that model being so heavy but I guess it's possible with a full load of batteries, retracts, 7 - 8 servos, and a glass/paint finish.

Sure, the airframe could fly at that weight...but the toki only has 2.5 pounds of thrust, tops.
Move the engine forward on the Bob-E-cat as far as you can. Remember, the pipe is back there, too.
I had a vampire done for Toki power...had to add 12 ounces of noseweight, it killed the project.
Aim for under four pounds. Three if you can!

3-4 lbs. should be very do-able with film covering and attention to the amount of glue used. I'm also not convinced flaps on a model of this size are needed nor offer much benefit. Eliminating those will save an ounce or so. Do that a few times and the weight will be reasonable for the Toki.

BTW, I also have a DJ-1 sitting here ready to fly. It's been in that state for over a year [sm=eek.gif]. I just haven't had time to run in the engine and take it out to the field.

I remember hearing some time back that Toki was supposed to release a slightly larger engine than the current .18. Did anything ever come of that?

3 pounds ain't easy. But then you will get PERFORMANCE!
Definitely no flaps. No need at all. No retracts. No rudders, either, especially since you will need to servos for that.

Fly the DJ1, it should be great. Light. Beyond running in the engine, tune the pipe properly.
I am dialing in a new engine setup for my Kyosho Sabre, I will do it on a test bench before it goes into the fuse. Pipe tuning is critical to performance.
The new 27 engine, they have had problems with it, and it takes a different fan, too. Not sure if the diameter is the same. I need to bug them for more info.

When I get around to running my .18, I'm going to start at 340mm per my documentation. I left the header a little long so I can pull the pipe out, or shorten it as needed. Based on the hot humid air we have here in Texas, I'll be sure to get the pipe right before I fly. I haven't weighed the DJ-1 yet, but it feels very light. I installed a Robart nose retract instead of the Pilot unit so I could have ground steering. Even with that gear and the two servos needed to make it function, I still needed to add 1 oz. to the nose to achive balance. I figure the retract takes the place of dead weight